Mesophase-induced Vitrification in Coordination Polymers via Aliphatic Chain Dynamics

Mesophase-induced Vitrification in Coordination Polymers via Aliphatic Chain Dynamics | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Mesophase-induced Vitrification in Coordination Polymers via Aliphatic Chain Dynamics Hoi Ri Moon, Minhyuk Kim, Hoe-yeon Jeong, Yelim Lee, Eun-chae Jeon This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7266933/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract Hybrid glasses derived from coordination polymers (CPs) promise a fusion of processability and structural functionality, yet their formation is fundamentally limited by poor thermal stability and high melting points. Here, we demonstrate a mesophase-mediated vitrification mechanism in a series of magnesium-based CPs (MgC n DC, n = 2–7) featuring aliphatic dicarboxylate linkers. Upon thermal desolvation, these frameworks transition into a mesomorphic state that retains coordination integrity while inducing conformational disorder in the organic substructure. This intermediate state enables a direct glass transition without requiring full melting. The resulting glasses exhibit distinct calorimetric transitions and tunable mechanical properties governed by chain length and topology. Furthermore, only the longest-chain member ( n = 7) is also capable of conventional melting after forming the mesophase, leading to a melt-quenched glass with lower mechanical stiffness due to partial disruption of its metal-organic backbone. Spectroscopic and structural analyses reveal that mesophase vitrification proceeds via unlocking rotational freedom in the hydrocarbon chains, drawing strong parallels to semicrystalline polymer behaviour. These findings establish a design strategy for vitrifiable coordination networks by integrating principles from polymer dynamics and mesomorphism. Physical sciences/Chemistry/Materials chemistry/Metal–organic frameworks Physical sciences/Chemistry/Inorganic chemistry/Solid-state chemistry Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction A glass is a type of amorphous solid, often described as a quenched supercooled liquid 1 . As the temperature increases, these solids undergo a glass transition, entering a viscoelastic and fluidic state above the glass transition temperature ( T g ). This transition is governed by the dynamical correlation of length and structural relaxation time, meaning that structural correlations within the amorphous phase significantly affect glass properties 2 . Despite advances in glass science, the energy landscape and mechanisms governing the glass transition remain only partially understood 3 – 5 . Thus, investigating the structural origins of several glassy materials is essential to refining existing theories. Identifying the exact structure of glass remains challenging, but tracing the origins from the parent crystalline structure may provide insight 6 . Glasses derived from coordination polymers (CPs) and metal–organic frameworks (MOFs) represent a growing class of hybrid materials that offer the mechanical versatility of amorphous solids combined with the tunability of crystalline architectures 7 . However, most carboxylate-based CPs decompose before reaching their melting points, precluding traditional melt-quenching methods 8 – 10 . To induce vitrification while bypassing thermal decomposition, our previous work focused on designing a framework with low melting temperature ( T m ) 11 . By incorporating an adipate linker and Mg²⁺/Mn²⁺ metal nodes, we developed meltable networks that liquefy before thermal decomposition, enabling vitrification upon cooling. Alternatively, vitrification methods that do not involve melting such as solvent-stimulated perturbation 12 , desolvation 13 , and ball-milling 14 , 15 have been investigated to introduce distortions in the metal node environment. Still, their mechanisms remain insufficiently understood, hindering the rational design of vitrifiable frameworks. A fundamental challenge is identifying structural motifs within CPs that can introduce dynamic disorder sufficient for vitrification while preserving coordination integrity. Expanding upon these strategies, we propose that aliphatic α, ω-dicarboxylate linkers ((COO)(CH 2 ) n (COO) − , C n DCs) enable a mesophase route to vitrification because their inherent conformational flexibility leads to thermotropic behaviour, a temperature-driven tendency to form a mesophase. A mesophase is an intermediate state between a perfect crystal and an isotropic liquid, whose combination of crystalline and liquid-like character enables a glass transition 16 . Achieving such a state requires creating a certain level of dynamic disorder while preserving partial crystalline order 17 . We posit that the conformational flexibility of aliphatic ligands, originating from their rotatable C-C single bonds, is ideal for introducing this dynamic disorder directly within the crystal lattice 18 , 19 . This approach is based on the thermotropic nature of aliphatic linkers. The ability of their alkane chains to adopt various rotational isomers (rotamers) introduces dynamic disorder, a principle supported by previous studies. For instance, the adipate linker ( n = 4) is known to possess different conformations with distinct potential energy levels within the crystal structure of CPs 20 , providing a structural basis for temperature-driven disorder. Similarly, hybrid organic-inorganic perovskites containing aliphatic monocarboxylate linkers undergo an order-disorder transition within their organic subphase upon heating 21 – 23 . Thus, aliphatic linkers are suitable components for constructing crystals with thermotropic mesomorphism, a feature that facilitates the formation of hybrid glasses without melting. In this work, we demonstrate that a series of magnesium aliphatic dicarboxylate CPs (the MgC n DC series, n = 2–7) forms a mesomorphic crystal with a conformationally disordered organic substructure via simple thermal desolvation. Upon further heating, this mesophase undergoes a direct glass transition without melting or bond cleavage. Aliphatic ligands introduce dynamic disorder upon heating without disrupting the coordination framework, offering a pathway to glass formation that parallels polymeric phase transitions. This process contrasts with conventional melting observed only in the longest-chain analogue, MgC 7 DC, thereby highlighting a fundamental divergence between mesophase vitrification and melt-quenching vitrification pathways. Our study reveals that the conformational mobility of the hydrocarbon chains, modulated by chain length and network topology, governs the glass transition behavior. The resulting glasses exhibit distinct thermal and mechanical properties, supporting the utility of mesophase engineering in hybrid glass design. Results Structural Characteristics and Thermal Evolution The C -MgC n DCs ( n = 2–7) series was synthesised in water, modified from a previously reported procedure (Supplementary Fig. 1) 24 . The single-crystal structures of C -MgC n DCs have been previously reported, which adopt all-trans linker conformations and octahedral Mg centres coordinated by linkers and water. The CPs in this series are divided into two types of network topologies depending on the length of the linkers: a 2C1 chain network for n = 2–4, and a fes net topology for n = 5–7 (Fig. 1 and Supplementary Fig. 2). In the case of the shorter linkers, C -MgC 2 DC and C -MgC 4 DC feature linkers with a syn η 1 monodentate binding mode, and C -MgC 3 DC adopts a syn-anti µ 2 - η 1 : η 1 bidentate manner in carboxylate bridging group of the linker. Despite these different binding modes, all three structures share the coordination formula of Mg( µ 2 -L)(H 2 O) 4 (L = linker), topologically forming a 2C1 chain network of a 2-connected 1D zigzag chain (Fig. 1 a). The chains are further organised into a superlattice structure through hydrogen bonds between coordinated water molecules and carbonyl oxygens and, in the case of C -MgC 3 DC, additional van der Waals (vdW) forces from dangling ligands. The longer-linker CPs ( n = 5–7) consistently form a 3-connected, (4·8 2 ) fes Shubnikov plane net topology (Fig. 1 b), and exhibit both syn-anti µ 2 - η 1 : η 1 bidentate bridging and syn η 1 modes, resulting in a Mg( µ 3 -L)(H 2 O) 3 formula. Longer linkers form 2D hydrophobic bilayer networks with thickness proportional to linker length (4.2 + 1.27 n Å) 25 . These networks form a lamellar structure with hydrophilic layers (3.7–4.1 Å), which are composed of hydrogen bonds between coordinated waters and carbonyl groups (Fig. 1 b, right). Thermal analysis revealed a series of temperature-induced phase transitions in the MgC n DCs. Figure 2 a illustrates the thermal evolution of C -MgC n DCs under continuous heating without any pre-treatment. The prefixes desC -, desL -, G - and reC - refer to the desolvated C -MgC n DC, the supercooled liquid state formed after the glass transition in the desC - state, the mesophase glass quenched from the desL - state, and the cold-crystallised phase, respectively (Supplementary Table 1). Most of the coordinating water molecules in the C -MgC n DCs were removed below 160°C, as confirmed by thermogravimetric analysis (TGA), resulting in the desC - phase with the general formula Mg(C n DC). The measured residual weights at 250°C for most samples matched the theoretical values for a fully anhydrous state (Supplementary Fig. 3 and Supplementary Table 2), except for desC -MgC 5 DC, which retained one coordinated water molecule after desolvation. MgC 2 DC and MgC 3 DC exhibited decomposition temperatures ( T d ) near 410°C, whereas MgC n DC with n = 4–7 showed similar T d values around 340°C (Supplementary Fig. 3). Notably, all samples displayed puffed and sintered morphologies after heating to T d , suggesting the formation of a fluidic intermediate during thermal treatment (Supplementary Fig. 4). To further investigate this behaviour, temperature-modulated differential scanning calorimetry (TMDSC) was performed on C -MgC n DCs up to temperatures just below their respective T d values (Fig. 2 a and Supplementary Fig. 5). The total heat flow ( HF tot ) was deconvoluted into reversing heat flow ( HF rev ) and non-reversing ( HF non−rev ) components, under the assumption that structural changes minimally affect thermal kinetics. This analysis distinguishes reversible transitions involving changes in heat capacity, such as the glass transition, from non-reversible transitions driven by kinetic processes 26 , 27 . In the HF tot signals, all C -MgC n DCs exhibited an initial endotherm desolvation event below 160°C. Following desolvation, a glass transition was observed in the HF rev traces of all samples, except C -MgC 2 DC, denoted as T g (Fig. 2 a, middle). Continued heating led to cold crystallisation at T c , observed in the HF non−rev signals for all samples except MgC 6 DC and MgC 7 DC (Fig. 2 a, right). The resulting reC -MgC n DC phase exhibited crystalline structures distinct from the original C -MgC n DCs, attributed to the rearrangements in the carboxylate binding modes due to the absence of coordinating water (Supplementary Fig. 6). Once crystallised, the reC -MgC n DCs showed no further thermal transitions before decomposition (Supplementary Fig. 7). In the case of desL -MgC 7 DC, an endothermic transition to a liquid crystal ( LC -) phase occurred at T lc , followed by melting at T m prior to decomposition 16 , 28 . Upon quenching, the molten MgC 7 DC formed a different glassy state, mqG -, with a calorimetric T g distinct from that of the desG - phase, denoted as T g mq (Supplementary Fig. 8). Optical microscopy confirmed the glassy morphology of the desG - and mqG - phases, whereas the C - and desC - phases retained a powdery crystalline form (Fig. 2 b and Supplementary Figs. 9 and 20). Although the desG - phase could not be isolated and no calorimetric T g was observed for MgC 2 DC, its reC - phase exhibited a monolithic, glassy morphology, suggesting vitrification occurred during heating. This entire thermal evolution is summarised in Fig. 2 c. 1 H nuclear magnetic resonance (NMR) spectroscopy confirmed that the ligands retained their original structures within the polymeric network in all glassy states (Supplementary Fig. 10). Mesophase-driven glass transition Most hybrid glasses have shown a glass transition only in the second heating cycle because the original crystalline state lacks any glassy regions and vitrifies only after the first heating cycle. In contrast, MgC n DC series undergo both a calorimetric glass transition and cold crystallisation in the first DSC heating cycle even without pretreatment. This arises from the lability in carboxylate binding modes and flexibility in the aliphatic moieties. Based on the initial crystal structures of the C -MgC n DCs, a plausible mechanism for the coordination structural rearrangements during desolvation can be proposed. In all C -MgC n DCs, non-coordinated oxygen atoms are positioned 3.2–3.4 Å from the metal nodes, which could allow them to form chelate bonds with the Mg centres upon desolvation. Subsequently, neighbouring oxygen atoms from other ligands (4.0–4.2 Å away) could then approach the nodes. These potential movements would cause distortions in the alkyl-chain conformation. These rearrangements impose steric torsion on the ligands and introduce disorder into the hydrophobic domains as in semicrystalline polymers 29 . The superlattice frameworks and the conformers in the aliphatic ligands drive both glass transition and cold crystallisation on heating. Above T g , alkyl chains can adopt multiple conformations. Thus, as shown in Fig. 3 a, amorphous domains in the lamellar structure exhibit thermotropic mesomorphism with a mobile fluidic subphase 30 – 32 , while SBUs remain intact owing to the rigid Mg–L bonds. Cold crystallisation is driven by freely rotating chains, which enhance interchain interactions, leading to chain repacking in the organic substructure. In C -MgC 2 DC and C -MgC 4 DC, which feature 1D chain networks, desolvation transforms the crystals into an anti-parallel lamellar superlattice, where electrostatic repulsion between the opposing layers restricts the conformational rotation of the hydrocarbon spacers (Fig. 3 b). Although C -MgC 3 DC has a 1D chain network, it also possesses a secondary network of hydrogen bonds between non-bonding carboxylates and coordinated water molecules. This creates a superlattice of alternating metal node and organic layers, analogous to the lamellar structure of the longer-chain CPs. Therefore, the thermal behaviour of MgC 3 DC is expected to more closely resemble that of the longer-chain CPs ( n = 5–7) rather than the shorter-chain CPs ( n = 2 and 4). To elucidate the mechanism of thermotropic behaviour of MgC n DCs featuring lamellar and 1D chain structures, ex-situ X-ray powder diffraction (XRPD) was conducted for MgC 5 DC and MgC 4 DC across their C -, desC -, desG -, and reC - phases. As shown in Fig. 4 a, the representative lamellar crystal, C -MgC 5 DC, showed the disappearance of hydrophilic layers upon desolvation, resulting in reduced interlamellar spacing, evidenced by a shift in the first sharp diffraction peak (FSDP) from 2 θ = 6.18° to 8.42–8.60° corresponding to a decrease in d -spacing from 14.3 to 10.3–10.5 Å. In contrast, C -MgC 4 DC, representing a 1D chain structure, initially exhibited the higher-angle first diffraction peak (11.86°), corresponding to the shortest d -spacing (7.6 Å) among the samples. Upon desolvation, the peak position shifted to lower angles, indicating an increased distance between SBUs, reaching 9.3–12.7 Å across the post-desolvation phases. C -MgC 2 DC exhibited a similar increase in the d -spacing of its FSDP, while the thermal trend observed in the XRPD of C -MgC 3 DC was more consistent with that of the longer-chain CPs (Supplementary Fig. 11). This suggests that the thermal transition mechanism is influenced not only by the linker chain length but also by the network structure of the initial C - phase. Variable-temperature, time-resolved in-situ XRPD measurements were performed on MgC 4 DC and MgC 5 DC at temperatures corresponding to their C - (room temperature), desC - (180°C) and desL - (270°C) states (Supplementary Fig. 12–14). The FSDP shift trends were consistent with the ex-situ XRPD data, but the in-situ analysis provided detailed insight into the mechanism of the thermal transition. For the lamellar C -MgC 5 DC, the d -spacing of the FSDP was observed to decrease gradually over time at 180°C, directly showing the removal of the hydrophilic layer. In contrast, C -MgC 4 DC had already fully transformed to the desC - phase upon reaching 180°C and thus showed no significant changes over time (Supplementary Fig. 13). This difference is likely because the confined hydrophilic layers in the lamellar structure of MgC 5 DC form a stronger hydrogen-bonded network, which delays the desolvation process compared to that of the initial 1D chain structure of C -MgC 4 DC. At a higher temperature (270°C), the peaks for the desL - phase were not only broader than those of the rigid desC - phase but also exhibited significant fluctuations over time, confirming the high chain mobility of the supercooled liquid state. This suggests that both the glass transition and cold crystallisation are governed by the mobility of the hydrocarbon chains (Supplementary Fig. 14). Pair distribution function (PDF) analysis of synchrotron X-ray total scattering data revealed that long-range order was retained in desG -MgC 5 DC, desG -MgC 6 DC, and even in mqG -MgC 7 DC, with structural correlations persisting up to 30–50 Å, whereas desG -MgC 4 DC exhibited order only up to approximately 15 Å (Supplementary Fig. 15). In addition, short- and medium-range order (1.2–5.0 Å) exhibited only minor changes in both desG - and mqG - phases compared to the initial C- state, suggesting that structural rearrangement was limited during either the mesophase glass transition or melting (Supplementary Fig. 16). Fourier-transform infrared (FTIR) spectroscopy was used to probe the further structural changes in the MgC n DC series (Fig. 4 b and Supplementary Fig. 17). Lower wavenumbers in the ν as (CH 2 ) mode (around 2940 cm − 1 ) reflect an increased population of gauche defects corresponding to greater chain disorder 33 , while lower wavenumbers in the ν as (COO) mode (around 1540 cm − 1 ) qualitatively indicate strong Mg–L bonds 34 . Desolvation caused a notable blueshift of the ν as (COO), confirming an alteration of the carboxylate binding mode. The changes in the ν as (CH₂) upon desolvation showed an odd–even alternation, reflecting a carbon-number parity similar to that observed in n -alkane derivatives 35 , 36 . Specifically, the odd-numbered chains exhibited an increase in disorder, whereas the even-numbered chains showed a reduction in the number of gauche conformations. Notably, after mesophase vitrification, the ν as (COO) and ν as (CH 2 ) in MgC n DCs both exhibited only minor changes compared to those observed during desolvation (Supplementary Table 3). These odd-even trends reflect a competition between the vdW stabilisation of the hydrocarbon chains and electrostatic repulsion of the terminal carboxyl groups 37 , 38 . In the odd-numbered chains, an all-trans conformation forces the carboxylate groups into a cis -like arrangement, inducing electrostatic repulsion. This inherent instability provides a driving force for the chains to reconfigure and increase their disorder when the coordination state is rearranged during desolvation. Conversely, the even-numbered chains can adopt a more ordered arrangement with fewer gauche conformations, as their all-trans state places the carboxylates in a stable, trans -like arrangement. This model helps to account for the observed FTIR trends in the various states of MgC n DCs. The desolvation process for this system induces large spectroscopic shifts and a pronounced odd-even effect because it involves significant atomic rearrangement, such as the translational motion of carbonyl carbons 13 , 39 . In contrast, the glass transition of MgC n DCs involves only minor interaction changes. This implies that the glass transition is driven by smaller-scale motions, such as the mobility of the hydrocarbon chains, rather than by changes in coordination state or the cleavage of Mg-L bonds. PDF analysis also showed that the Mg⋯Mg correlations at 8–15 Å produced a sharp peak in odd-numbered glasses, whereas even-numbered glasses exhibited broad peaks in that region, implying greater positional distortion of Mg and hence higher chain mobility in the even-numbered series during vitrification (Supplementary Fig. 16). Cold crystallisation of desL -MgC n DCs exhibited comparable FTIR trends, indicating that the main mechanism is the reordering of chains to maximise hydrophobic interactions, as evidenced by the ν as (CH 2 ) redshift (Fig. 4 b) 40 , 41 . Additionally, partial crystallisation was observed in desL -MgC 6 DC under applied shear stress or prolonged heating, despite the absence of a distinct calorimetric T c , supporting the mechanism whereby conformational chain mobility governs the thermal behaviours in MgC n DCs (Supplementary Fig. 18) 42 , 43 . The C -, desC - and desG - phases of MgC 6 DC and MgC 7 DC showed similar XRPD and FTIR trends to those of MgC 5 DC, while MgC 2 DC behaved similarly to MgC 4 DC (Supplementary Figs. 11 and 17). Thermomechanical Properties The thermal behaviour trends and mechanical properties of the MgC n DCs varied with the length of the alkyl chain (Figs. 5 and 6 ). The calorimetric transition temperatures ( T d , T g , and T c ) were identified by TGA and TMDSC and were observed to decrease as n increased (Fig. 5 a). T d decreased significantly from n = 2–4 and then showed little variation from n = 4–7. This observation agrees with previous reports 42 that the influence of the alkyl chain on the carboxylate group became smaller after n = 4. Considering the reported trend in ligand p K a values, we infer that the T d values were primarily influenced by the strength of the Mg–O bonds 43 . T g decreased monotonically, mirroring the trend in organic polymers as spacer length increases 44 , 45 . Each added methylene unit acts as a flexible hinge, increasing the conformational freedom of the chains and lowering the energy barrier for segmental motion. The absence of an odd-even effect in T g indicates that the glass transition in MgC n DCs is dictated primarily by vdW forces rather than by the odd-even effects seen in ionic glasses, reinforcing the proposed mechanism for their glass transition 46 , 47 . Thermodynamic parameters derived from DSC measurements (Fig. 5 b) and principles of polymer physics were used to explain the trends in T c . The crystallisation enthalpy and entropy (Δ H c and Δ S c ) represent the differences in energy and accessible chain conformations between the desL- and reC - states, respectively. Δ H c followed the order MgC 3 DC > MgC 2 DC > MgC 5 DC > MgC 4 DC. For chains of length n ≤ 3, the Δ H c of MgC n DC exceeded the standard molar fusion enthalpies of the corresponding H₂C n DC ligands 36 , but the trend reversed for n ≥ 4. Since the enthalpy of H₂C n DC arises mainly from the breaking of hydrogen bonds, the higher Δ H c of MgC n DC with n ≤ 3 chains implies that electrostatic stabilisation dominated during crystallisation, whereas for n ≥ 4 chains vdW interactions prevailed. The order of Δ S c for the MgC n DCs was the same as that of Δ H c . Except for MgC 3 DC, all MgC n DCs exhibited lower Δ S c values than the standard molar fusion entropies of n -alkanes of equivalent chain length, (CH 2 ) n (CH 3 ) 2 . Notably, MgC 4 DC and MgC 5 DC displayed Δ S c values of 22.58 and 33.02 J·mol − 1 ·K − 1 , respectively. The difference between these two values (10.44 J·mol − 1 ·K − 1 ) falls within the typical range of conformational entropy contributed by a single methylene group (7–12 J·mol − 1 ·K − 1 ) 16,48 . Taken together, the observed trend in Δ S c and the inverse T g - n relationship are characteristic of a conformationally disordered crystal (condis crystal), a type of mesophase. A condis crystal is a state that possesses dynamic disorder arising from the internal conformational disorder of its components 17 . Consequently, its thermodynamic parameters are strongly correlated with the chain length, n , as seen in this case. This model provides a framework for explaining several key experimental observations. For instance, the absence of a detectable T g in MgC 2 DC can be attributed to the limited conformational states of its short n -butane-like chain (only two non-equivalent conformers), which allows its glass transition to occur too rapidly for calorimetric detection. Conversely, for the longer chains ( n = 4–7), the exponential growth in accessible conformers 49 increases the activation energy and slows the crystallisation kinetics 50 , 51 . This slowing of the ordering process explains both the higher T c of MgC 5 DC compared to MgC 4 DC, and the complete disappearance of a calorimetric T c for the longest-chain members, MgC 6 DC and MgC 7 DC 52 . The enhanced stability in the desL - and desG - states for these longer spacers is driven by greater interchain forces and increased molecular entanglement 53 , 54 . Taken together, these results indicate that MgC n DCs crystallise via a mesophase-mediated pathway governed by the reordering of their aliphatic chains, in a manner consistent with established polymer crystallisation models 55 , 56 . The elastic modulus ( E ) and hardness ( H ) for desG -MgC n DC ( n = 4–6) and mqG -MgC 7 DC were measured by nanoindentation. The E and H were calculated from the load-depth curves of glass samples (Fig. 6 a and Supplementary Table 5). All samples were confirmed as amorphous by XRPD and exhibited plastic deformation under indentation. However, desG -MgC 4 DC presented propagated radial cracks, indicating the formation of a crystalline region during vitrification (Supplementary Fig. 19) 57 . This semicrystalline state increased E through denser packing within its crystalline domains but reduced H due to inefficient stress transfer in the anti-parallel lamellar superlattice 58 . Hence, desG -MgC 4 DC exhibited higher E and lower H (19.50 and 0.85 GPa) than desG -MgC 5 DC (17.48 and 0.92 GPa), which had a fully amorphised network. Notably, desG -MgC 6 DC exhibited enhanced E and H (58.09 and 2.19 GPa) compared to the isoreticular desG -MgC 5 DC, with values exceeding those of cement-based materials and reported organic crystals 59 , 60 . This implies a large amount of chain interlocking within the intralamellar space between SBUs (≈ 12 Å), amplifying interchain forces beyond those in entangled organic polymers 61 . In contrast, mqG -MgC 7 DC exhibited significantly lower E and H (2.60 and 0.10 GPa) than the desG -MgC n DCs. This difference originates from the distinctive multi-step melting process of MgC 7 DC. Prior to melting, an endothermic transition at T lc suggests a transition from the condis phase to a liquid crystal phase. This phase transition is supported by ex-situ XRPD data showing that a lamellar order peak (2 θ = 5.50°, d = 16.1 Å) temporarily reappears in the initial stage of the LC - phase, but only this long-range order disappears over time (Supplementary Fig. 18). In addition, upon melting, Mg–L bonds dissociated, as evidenced by weight loss and the formation of uncoordinated carbonyl at T m (Supplementary Figs. 3 and 16). The sample also exhibited browning post-melt, which indicated partial decomposition of the ligand (Supplementary Fig. 20). Thus, the combination of interlamellar disorder induced in the LC - phase and the partial disassembly of the rigid SBU backbones during melting increases segmental mobility in the melt-quenched glass, resulting in its softer mechanical properties (Fig. 6 b). Discussion Glass transition and melting behaviours in MOFs and CPs have been interpreted within two frameworks based on inorganic glasses or organic polymers. The thermal transitions of MgC n DCs illustrate both viewpoints and highlight the link between coordination polymers and organic polymers in glass formation. The lamellar structures of C -MgC n DCs mirror a network of organic polymers. Ligands serve as spacers through covalent and coordination bonds while SBUs form rigid backbones similar to the main chains of bottlebrush polymers 63 . A key distinction lies in electrostatic properties. Organic polymers feature hydrocarbon backbones and side chains whereas SBUs and ligands in CPs carry opposing electrostatic charges. This contrast creates crystallographically distinct interaction spaces that periodically enhance nanoscale chain rotation and drive macroscopic changes in viscosity and vitrification. In a manner akin to crosslinked polymers, SBUs dissociate above T m , which increases segmental mobility and yields softer, more stretchable glass networks reminiscent of an elastomer 64 . Melting was observed only in MgC 7 DC, which suggests that longer carbon chains supply greater entropy of fusion and supports the hypothesis that the rotamer population governs framework meltability. In summary, we have developed a route to vitrify CPs by forming a mesophase with aliphatic dicarboxylate ligands under thermal desolvation. This mesophase arises from the unique properties of aliphatic dicarboxylates. Desolvation creates partially disordered networks due to versatile binding modes of the carboxylate groups. Within this mesophase, the rotatable C–C bonds of the hydrocarbon chains allow a mobile, supercooled liquid phase to form upon heating above the T g , which then vitrifies into a glass upon subsequent cooling. Notably, the mesophase-derived glasses exhibited hard mechanical properties while the melt-quenched glasses were comparatively softer due to different chain packing arrangements, with the former resembling semicrystalline polymers. This work broadens strategies for hybrid glass fabrication and provides a pathway to design vitrifiable coordination networks using insights from the organic polymer and liquid crystal fields. Methods Mechanical properties measurement Samples were placed on glass slides and vitrified under argon at 5 K above their respective T g or T m . They were held at this temperature for 15 minutes and subsequently quenched in room air, with argon flow maintained to prevent oxidative interference. All desG - samples were measured in their as-prepared state without further treatment, whereas mqG -MgC 7 DC was polished using 600-grit sandpaper and rinsed with acetone (Supplementary Fig 16). Nanoindentation was performed using an Anton-Paar nanoindenter with a Berkovich tip. E and H were extracted from load–depth curves using the Oliver–Pharr method. Maximum loads were set at 5 mN for mqG -MgC 7 DC, 15 mN for desG -MgC 4 DC and MgC 5 DC, and 80 mN for desG -MgC 6 DC. Values near the maximum penetration depth were taken as the representative E and H for each sample. Declarations Data availability The data that support the findings of this work are presented in the Supplementary Information. Additional data are available on request from the corresponding authors. Acknowledgments This work supported by the National Research Foundation of Korea (NRF) through the Nano & Material Technology Development Program funded by the Ministry of Science and ICT (Grant No. RS-2024-00408180 to E.-c.J.) and through NRF grants (NRF- 2020R1A2C3008908 and 2021R1A6A10039823 to H.R.M.). This work also supported by a Korea Basic Science Institute (National Research Facilities and Equipment Center) grant funded by the Ministry of Education (2020R1A6C101B194 to H.R.M.). The synchrotron radiation experiments were performed at BL04B2 (Proposal No. 2024B1316) and BL13XU (Proposal No. 2024B1639) of SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI). Author contributions M.K. and H.R.M. conceived the idea for the project. M.K. designed the experiments and performed the synthesis. M.K. and Y.L. conducted characterisation of the thermal transitions and their results in CPs. H.-y.J. analysed the mechanical properties of the glassy CPs under direction of E.-c.J.. M.K. and H.R.M. wrote the paper, and all the authors contributed to preparing the manuscript. Competing interests The authors declare no competing interests. References Debenedetti, P. G. & Stillinger, F. H. Supercooled liquids and the glass transition. Nature 410 , 259–267 (2001). 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Chem. 15 , 219–247 (2024). Additional Declarations There is NO Competing Interest. Supplementary Files f225NCsup250731moon.pdf Supplementary Informations Cite Share Download PDF Status: Under Review Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7266933","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":500512757,"identity":"7fb89913-ec47-44fa-ba13-3b20c31ad024","order_by":0,"name":"Hoi Ri Moon","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA0klEQVRIiWNgGAWjYBACAwbGBoYEEIu9gYEZIsZGrBaeA0RrgQGJBCK1mLM3t314mGMjZy75+Jh0QQ2DPH8DW9oHfFosew42z0jclmZsOTstTXrGMQbDGQfYDs/A67Abic0MidsOJ264nWN2m4eNgXEDA3szfr/Atdw8/+02zz8GexK03OBhu83bxpC4gYHtMH4tZw6CtKQZG5xJM//N2yeRPOMwWzJ+LcfbHzP+3GYjZ3D88GNjnm82tv3tbcZ4taADCQZY7IyCUTAKRsEooAAAAMh+R8tvN8PCAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0002-6967-894X","institution":"Ewha Womans University","correspondingAuthor":true,"prefix":"","firstName":"Hoi","middleName":"Ri","lastName":"Moon","suffix":""},{"id":500512758,"identity":"c1faf081-522f-4ec6-8d4c-52217d8ad7eb","order_by":1,"name":"Minhyuk Kim","email":"","orcid":"https://orcid.org/0000-0002-5244-9083","institution":"Ulsan National Institute of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Minhyuk","middleName":"","lastName":"Kim","suffix":""},{"id":500512759,"identity":"ac6c4513-0f99-48f1-b45e-86267080bd8e","order_by":2,"name":"Hoe-yeon Jeong","email":"","orcid":"","institution":"University of Ulsan","correspondingAuthor":false,"prefix":"","firstName":"Hoe-yeon","middleName":"","lastName":"Jeong","suffix":""},{"id":500512760,"identity":"e7bef240-13ae-4d0b-8b90-455500ea2ae6","order_by":3,"name":"Yelim Lee","email":"","orcid":"https://orcid.org/0000-0001-7126-7907","institution":"Ewha Womans University","correspondingAuthor":false,"prefix":"","firstName":"Yelim","middleName":"","lastName":"Lee","suffix":""},{"id":500512761,"identity":"24fd33b7-8a91-4700-b8bd-5dcd61455bdc","order_by":4,"name":"Eun-chae Jeon","email":"","orcid":"https://orcid.org/0000-0002-6951-219X","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Eun-chae","middleName":"","lastName":"Jeon","suffix":""}],"badges":[],"createdAt":"2025-08-01 03:30:16","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7266933/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7266933/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":89258157,"identity":"9c15572f-746d-4117-a143-43cf2d49ec84","added_by":"auto","created_at":"2025-08-18 06:19:36","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":239601,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eStructures and topologies of the MgC\u003c/strong\u003e\u003csub\u003e\u003cem\u003e\u003cstrong\u003en\u003c/strong\u003e\u003c/em\u003e\u003c/sub\u003e\u003cstrong\u003eDC (\u003c/strong\u003e\u003cem\u003e\u003cstrong\u003en \u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e= 2–7)\u003c/strong\u003e \u003cstrong\u003eseries. a\u003c/strong\u003e, Representations for the shorter-chain CPs (\u003cem\u003en \u003c/em\u003e= 2–4), showing the underlying 2C1 chain network, and corresponding single-crystal X-ray structures. \u003cstrong\u003eb\u003c/strong\u003e, Representations for the longer-chain CPs (\u003cem\u003en \u003c/em\u003e= 5–7), showing the underlying \u003cem\u003e\u003cstrong\u003efes \u003c/strong\u003e\u003c/em\u003eplane\u003cem\u003e\u003cstrong\u003e \u003c/strong\u003e\u003c/em\u003enet, the corresponding single-crystal X-ray structure, and a schematic structure of the resulting lamellar superlattice. Colour code: Mg, light green; O, red; C, grey; H, white. To clarify the underlying topology, linker carbon chains are simplified to sticks and all hydrogen atoms of the framework are omitted.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7266933/v1/64339292319f298469b707ef.png"},{"id":89258159,"identity":"46f86f52-9fb3-48c0-b796-78f099dad89e","added_by":"auto","created_at":"2025-08-18 06:19:36","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":250923,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThermal behaviour of MgC\u003c/strong\u003e\u003csub\u003e\u003cem\u003e\u003cstrong\u003en\u003c/strong\u003e\u003c/em\u003e\u003c/sub\u003e\u003cstrong\u003eDCs.\u003c/strong\u003e \u003cstrong\u003ea\u003c/strong\u003e,\u003cstrong\u003e \u003c/strong\u003eTMDSC data (\u003cstrong\u003eHF\u003c/strong\u003e\u003csub\u003etot\u003c/sub\u003e, left) deconvoluted into reversing (\u003cstrong\u003eHF\u003c/strong\u003e\u003csub\u003erev\u003c/sub\u003e, middle) and non-reversing (\u003cstrong\u003eHF\u003c/strong\u003e\u003csub\u003enon-rev\u003c/sub\u003e, right) heat flows for MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs. \u003cstrong\u003eb\u003c/strong\u003e, Optical images of \u003cem\u003e\u003cstrong\u003ereC\u003c/strong\u003e\u003c/em\u003e-MgC\u003csub\u003e2\u003c/sub\u003eDC and \u003cem\u003e\u003cstrong\u003edesG\u003c/strong\u003e\u003c/em\u003e-MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs (\u003cem\u003en \u003c/em\u003e= 3–7), showing glassy morphology.\u003cstrong\u003e c\u003c/strong\u003e, Summary of thermal phase transition for \u003cem\u003e\u003cstrong\u003eC-\u003c/strong\u003e\u003c/em\u003eMgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs observed during the first heating step in TMDSC measurements. Phase definition and prefix meanings are given in the main text and Supplementary Table 1.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7266933/v1/4f02491cc45ec490d01aa171.png"},{"id":89259456,"identity":"9ba5d66b-b3dc-4107-8ca8-f68d194822ce","added_by":"auto","created_at":"2025-08-18 06:27:36","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":162964,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThermal transition mechanism of MgC\u003c/strong\u003e\u003csub\u003e\u003cem\u003e\u003cstrong\u003en\u003c/strong\u003e\u003c/em\u003e\u003c/sub\u003e\u003cstrong\u003eDCs.\u003c/strong\u003e \u003cstrong\u003ea \u003c/strong\u003eand\u003cstrong\u003e b\u003c/strong\u003e, Mesophase-driven phase transition pathways, shown schematically for lamellar networks (\u003cem\u003en \u003c/em\u003e= 3 and 5–7) and 1D chain (\u003cem\u003en \u003c/em\u003e= 2 and 4), respectively.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7266933/v1/110f78a8c5028b400451bb29.png"},{"id":89258163,"identity":"2b7bed7e-6e20-4b51-a390-1c7dcd6d2193","added_by":"auto","created_at":"2025-08-18 06:19:36","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":48589,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eStructural Characterisation of MgC\u003c/strong\u003e\u003csub\u003e\u003cem\u003e\u003cstrong\u003en\u003c/strong\u003e\u003c/em\u003e\u003c/sub\u003e\u003cstrong\u003eDCs following thermal transitions.\u003c/strong\u003e \u003cstrong\u003ea\u003c/strong\u003e, Ex-situ XRPD patterns (Cu K\u003csub\u003eα\u003c/sub\u003e) of MgC\u003csub\u003e5\u003c/sub\u003eDC and MgC\u003csub\u003e4\u003c/sub\u003eDC in successive, thermally treated states. \u003cstrong\u003eb\u003c/strong\u003e, FTIR analysis of the changes in the \u003cem\u003eν\u003c/em\u003e\u003csub\u003eas\u003c/sub\u003e(CH\u003csub\u003e2\u003c/sub\u003e) and \u003cem\u003eν\u003c/em\u003e\u003csub\u003eas\u003c/sub\u003e(COO) wavenumbers for the MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs (\u003cem\u003en \u003c/em\u003e= 4–7) across different states. The data for \u003cem\u003en \u003c/em\u003e= 2 and 3 were excluded as some states yielded only weak or ambiguous peaks in these regions. The full spectra are presented in Supplementary Fig. 17, and the corresponding peak positions are summarised in Supplementary Table 3.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7266933/v1/d73a1efcf66cf662d681b661.png"},{"id":89259455,"identity":"a022b6b0-df19-41aa-a604-5ecc21612bd8","added_by":"auto","created_at":"2025-08-18 06:27:36","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":30299,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eTransition temperatures and thermodynamic parameters of MgC\u003c/strong\u003e\u003csub\u003e\u003cem\u003e\u003cstrong\u003en\u003c/strong\u003e\u003c/em\u003e\u003c/sub\u003e\u003cstrong\u003eDCs.\u003c/strong\u003e \u003cstrong\u003ea\u003c/strong\u003e, Characteristic temperatures, including decomposition (\u003cem\u003eT\u003c/em\u003e\u003csub\u003ed\u003c/sub\u003e), cold crystallisation (\u003cem\u003eT\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e), melting (\u003cem\u003eT\u003c/em\u003e\u003csub\u003em\u003c/sub\u003e), \u003cem\u003e\u003cstrong\u003edesL\u003c/strong\u003e\u003c/em\u003e-to-\u003cem\u003e\u003cstrong\u003eLC\u003c/strong\u003e\u003c/em\u003e transition (\u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003elc\u003c/em\u003e\u003c/sub\u003e), glass transition of \u003cem\u003e\u003cstrong\u003edesG\u003c/strong\u003e\u003c/em\u003e- (\u003cem\u003eT\u003c/em\u003e\u003csub\u003eg\u003c/sub\u003e) and \u003cem\u003e\u003cstrong\u003emqG\u003c/strong\u003e\u003c/em\u003e- (\u003cem\u003eT\u003c/em\u003e\u003csub\u003eg\u003c/sub\u003e\u003csup\u003emq\u003c/sup\u003e), and \u003cem\u003e\u003cstrong\u003eC\u003c/strong\u003e\u003c/em\u003e-to-\u003cem\u003e\u003cstrong\u003edesC\u003c/strong\u003e\u003c/em\u003e transition induced by desolvation (\u003cem\u003eT\u003c/em\u003e\u003csub\u003edes\u003c/sub\u003e).\u003cstrong\u003e b\u003c/strong\u003e, Thermodynamic parameters derived from cold crystallisation, molar enthalpies (Δ\u003cem\u003eH\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e) and entropies (Δ\u003cem\u003eS\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e) of crystallisation. For linear \u003cem\u003en\u003c/em\u003e-alkanes and H\u003csub\u003e2\u003c/sub\u003eC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs, Δ\u003cem\u003eH\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e and Δ\u003cem\u003eS\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e indicate their reported standard molar enthalpies and entropies\u003csup\u003e36\u003c/sup\u003e. Detail values are presented in Supplementary Table 4.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-7266933/v1/e3b2fffacb51f7dac356a7ea.png"},{"id":89258161,"identity":"15dbb6bd-c683-413b-8241-0554e6244a4c","added_by":"auto","created_at":"2025-08-18 06:19:36","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":60442,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMechanical properties of \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003edesG\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e-MgC\u003c/strong\u003e\u003csub\u003e\u003cem\u003e\u003cstrong\u003en\u003c/strong\u003e\u003c/em\u003e\u003c/sub\u003e\u003cstrong\u003eDCs and \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003emqG\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e-MgC\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e7\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eDC.\u003c/strong\u003e \u003cstrong\u003ea\u003c/strong\u003e, \u003cem\u003eE \u003c/em\u003eand \u003cem\u003eH\u003c/em\u003e of glassy MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs (\u003cem\u003en \u003c/em\u003e= 4–7). Comparison data are from a previous study (\u003cem\u003e\u003cstrong\u003eG\u003c/strong\u003e\u003c/em\u003e-Mg-adp)\u003csup\u003e11\u003c/sup\u003e and literature\u003csup\u003e62\u003c/sup\u003e. \u0026nbsp;\u003cstrong\u003eb\u003c/strong\u003e, Schematic illustration of the mechanisms underlying the mechanical differences between the \u003cem\u003e\u003cstrong\u003edesG\u003c/strong\u003e\u003c/em\u003e- and \u003cem\u003e\u003cstrong\u003emqG\u003c/strong\u003e\u003c/em\u003e- phases in MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-7266933/v1/1dc135aa4868c3c3cd749ac6.png"},{"id":89260359,"identity":"0e90284e-e3f4-402e-952c-08035a0efa60","added_by":"auto","created_at":"2025-08-18 06:43:37","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1885727,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7266933/v1/528b377d-6b60-48d8-a9d2-fe7c88c0a543.pdf"},{"id":89258169,"identity":"0ca7d866-5e6f-4d58-9c2d-321b1ef0df55","added_by":"auto","created_at":"2025-08-18 06:19:36","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":2493532,"visible":true,"origin":"","legend":"Supplementary Informations","description":"","filename":"f225NCsup250731moon.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7266933/v1/48008a31ef6d209205b6d94e.pdf"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Mesophase-induced Vitrification in Coordination Polymers via Aliphatic Chain Dynamics","fulltext":[{"header":"Introduction","content":"\u003cp\u003eA glass is a type of amorphous solid, often described as a quenched supercooled liquid\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e. As the temperature increases, these solids undergo a glass transition, entering a viscoelastic and fluidic state above the glass transition temperature (\u003cem\u003eT\u003c/em\u003e\u003csub\u003eg\u003c/sub\u003e). This transition is governed by the dynamical correlation of length and structural relaxation time, meaning that structural correlations within the amorphous phase significantly affect glass properties\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e. Despite advances in glass science, the energy landscape and mechanisms governing the glass transition remain only partially understood\u003csup\u003e\u003cspan additionalcitationids=\"CR4\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e. Thus, investigating the structural origins of several glassy materials is essential to refining existing theories. Identifying the exact structure of glass remains challenging, but tracing the origins from the parent crystalline structure may provide insight\u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e. Glasses derived from coordination polymers (CPs) and metal\u0026ndash;organic frameworks (MOFs) represent a growing class of hybrid materials that offer the mechanical versatility of amorphous solids combined with the tunability of crystalline architectures\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e. However, most carboxylate-based CPs decompose before reaching their melting points, precluding traditional melt-quenching methods\u003csup\u003e\u003cspan additionalcitationids=\"CR9\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e. To induce vitrification while bypassing thermal decomposition, our previous work focused on designing a framework with low melting temperature (\u003cem\u003eT\u003c/em\u003e\u003csub\u003em\u003c/sub\u003e)\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e. By incorporating an adipate linker and Mg\u0026sup2;⁺/Mn\u0026sup2;⁺ metal nodes, we developed meltable networks that liquefy before thermal decomposition, enabling vitrification upon cooling. Alternatively, vitrification methods that do not involve melting such as solvent-stimulated perturbation\u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e, desolvation\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e, and ball-milling\u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e,\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e have been investigated to introduce distortions in the metal node environment. Still, their mechanisms remain insufficiently understood, hindering the rational design of vitrifiable frameworks. A fundamental challenge is identifying structural motifs within CPs that can introduce dynamic disorder sufficient for vitrification while preserving coordination integrity.\u003c/p\u003e\u003cp\u003eExpanding upon these strategies, we propose that aliphatic α, ω-dicarboxylate linkers ((COO)(CH\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e)\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003e(COO)\u003csup\u003e\u0026minus;\u003c/sup\u003e, C\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs) enable a mesophase route to vitrification because their inherent conformational flexibility leads to thermotropic behaviour, a temperature-driven tendency to form a mesophase. A mesophase is an intermediate state between a perfect crystal and an isotropic liquid, whose combination of crystalline and liquid-like character enables a glass transition\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e. Achieving such a state requires creating a certain level of dynamic disorder while preserving partial crystalline order\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e. We posit that the conformational flexibility of aliphatic ligands, originating from their rotatable C-C single bonds, is ideal for introducing this dynamic disorder directly within the crystal lattice\u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e,\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e. This approach is based on the thermotropic nature of aliphatic linkers. The ability of their alkane chains to adopt various rotational isomers (rotamers) introduces dynamic disorder, a principle supported by previous studies. For instance, the adipate linker (\u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;4) is known to possess different conformations with distinct potential energy levels within the crystal structure of CPs\u003csup\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e, providing a structural basis for temperature-driven disorder. Similarly, hybrid organic-inorganic perovskites containing aliphatic monocarboxylate linkers undergo an order-disorder transition within their organic subphase upon heating\u003csup\u003e\u003cspan additionalcitationids=\"CR22\" citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e. Thus, aliphatic linkers are suitable components for constructing crystals with thermotropic mesomorphism, a feature that facilitates the formation of hybrid glasses without melting.\u003c/p\u003e\u003cp\u003eIn this work, we demonstrate that a series of magnesium aliphatic dicarboxylate CPs (the MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDC series, \u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;2\u0026ndash;7) forms a mesomorphic crystal with a conformationally disordered organic substructure via simple thermal desolvation. Upon further heating, this mesophase undergoes a direct glass transition without melting or bond cleavage. Aliphatic ligands introduce dynamic disorder upon heating without disrupting the coordination framework, offering a pathway to glass formation that parallels polymeric phase transitions. This process contrasts with conventional melting observed only in the longest-chain analogue, MgC\u003csub\u003e7\u003c/sub\u003eDC, thereby highlighting a fundamental divergence between mesophase vitrification and melt-quenching vitrification pathways. Our study reveals that the conformational mobility of the hydrocarbon chains, modulated by chain length and network topology, governs the glass transition behavior. The resulting glasses exhibit distinct thermal and mechanical properties, supporting the utility of mesophase engineering in hybrid glass design.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cb\u003eStructural Characteristics and Thermal Evolution\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe \u003cb\u003eC\u003c/b\u003e-MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs (\u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;2\u0026ndash;7) series was synthesised in water, modified from a previously reported procedure (Supplementary Fig.\u0026nbsp;1)\u003csup\u003e\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e. The single-crystal structures of \u003cb\u003eC\u003c/b\u003e-MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs have been previously reported, which adopt \u003cem\u003eall-trans\u003c/em\u003e linker conformations and octahedral Mg centres coordinated by linkers and water. The CPs in this series are divided into two types of network topologies depending on the length of the linkers: a 2C1 chain network for \u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;2\u0026ndash;4, and a \u003cb\u003efes\u003c/b\u003e net topology for \u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;5\u0026ndash;7 (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and Supplementary Fig.\u0026nbsp;2). In the case of the shorter linkers, \u003cb\u003eC\u003c/b\u003e-MgC\u003csub\u003e2\u003c/sub\u003eDC and \u003cb\u003eC\u003c/b\u003e-MgC\u003csub\u003e4\u003c/sub\u003eDC feature linkers with a \u003cem\u003esyn η\u003c/em\u003e\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e monodentate binding mode, and \u003cb\u003eC\u003c/b\u003e-MgC\u003csub\u003e3\u003c/sub\u003eDC adopts a \u003cem\u003esyn-anti \u0026micro;\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003e-\u003cem\u003eη\u003c/em\u003e\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e:\u003cem\u003eη\u003c/em\u003e\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e bidentate manner in carboxylate bridging group of the linker. Despite these different binding modes, all three structures share the coordination formula of Mg(\u003cem\u003e\u0026micro;\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003e-L)(H\u003csub\u003e2\u003c/sub\u003eO)\u003csub\u003e4\u003c/sub\u003e (L\u0026thinsp;=\u0026thinsp;linker), topologically forming a 2C1 chain network of a 2-connected 1D zigzag chain (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea). The chains are further organised into a superlattice structure through hydrogen bonds between coordinated water molecules and carbonyl oxygens and, in the case of \u003cb\u003eC\u003c/b\u003e-MgC\u003csub\u003e3\u003c/sub\u003eDC, additional van der Waals (vdW) forces from dangling ligands. The longer-linker CPs (\u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;5\u0026ndash;7) consistently form a 3-connected, (4\u0026middot;8\u003csup\u003e2\u003c/sup\u003e) \u003cb\u003efes\u003c/b\u003e Shubnikov plane net topology (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb), and exhibit both \u003cem\u003esyn-anti \u0026micro;\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003e-\u003cem\u003eη\u003c/em\u003e\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e:\u003cem\u003eη\u003c/em\u003e\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e bidentate bridging and \u003cem\u003esyn η\u003c/em\u003e\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e modes, resulting in a Mg(\u003cem\u003e\u0026micro;\u003c/em\u003e\u003csub\u003e3\u003c/sub\u003e-L)(H\u003csub\u003e2\u003c/sub\u003eO)\u003csub\u003e3\u003c/sub\u003e formula. Longer linkers form 2D hydrophobic bilayer networks with thickness proportional to linker length (4.2\u0026thinsp;+\u0026thinsp;1.27\u003cem\u003en\u003c/em\u003e \u0026Aring;)\u003csup\u003e\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e. These networks form a lamellar structure with hydrophilic layers (3.7\u0026ndash;4.1 \u0026Aring;), which are composed of hydrogen bonds between coordinated waters and carbonyl groups (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb, right).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThermal analysis revealed a series of temperature-induced phase transitions in the MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea illustrates the thermal evolution of \u003cb\u003eC\u003c/b\u003e-MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs under continuous heating without any pre-treatment. The prefixes \u003cb\u003edesC\u003c/b\u003e-, \u003cb\u003edesL\u003c/b\u003e-, \u003cb\u003eG\u003c/b\u003e- and \u003cb\u003ereC\u003c/b\u003e- refer to the desolvated \u003cb\u003eC\u003c/b\u003e-MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDC, the supercooled liquid state formed after the glass transition in the \u003cb\u003edesC\u003c/b\u003e- state, the mesophase glass quenched from the \u003cb\u003edesL\u003c/b\u003e- state, and the cold-crystallised phase, respectively (Supplementary Table\u0026nbsp;1). Most of the coordinating water molecules in the \u003cb\u003eC\u003c/b\u003e-MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs were removed below 160\u0026deg;C, as confirmed by thermogravimetric analysis (TGA), resulting in the \u003cb\u003edesC\u003c/b\u003e- phase with the general formula Mg(C\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDC). The measured residual weights at 250\u0026deg;C for most samples matched the theoretical values for a fully anhydrous state (Supplementary Fig.\u0026nbsp;3 and Supplementary Table\u0026nbsp;2), except for \u003cb\u003edesC\u003c/b\u003e-MgC\u003csub\u003e5\u003c/sub\u003eDC, which retained one coordinated water molecule after desolvation. MgC\u003csub\u003e2\u003c/sub\u003eDC and MgC\u003csub\u003e3\u003c/sub\u003eDC exhibited decomposition temperatures (\u003cem\u003eT\u003c/em\u003e\u003csub\u003ed\u003c/sub\u003e) near 410\u0026deg;C, whereas MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDC with \u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;4\u0026ndash;7 showed similar \u003cem\u003eT\u003c/em\u003e\u003csub\u003ed\u003c/sub\u003e values around 340\u0026deg;C (Supplementary Fig.\u0026nbsp;3). Notably, all samples displayed puffed and sintered morphologies after heating to \u003cem\u003eT\u003c/em\u003e\u003csub\u003ed\u003c/sub\u003e, suggesting the formation of a fluidic intermediate during thermal treatment (Supplementary Fig.\u0026nbsp;4).\u003c/p\u003e\u003cp\u003eTo further investigate this behaviour, temperature-modulated differential scanning calorimetry (TMDSC) was performed on \u003cb\u003eC\u003c/b\u003e-MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs up to temperatures just below their respective \u003cem\u003eT\u003c/em\u003e\u003csub\u003ed\u003c/sub\u003e values (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea and Supplementary Fig.\u0026nbsp;5). The total heat flow (\u003cb\u003eHF\u003c/b\u003e\u003csub\u003etot\u003c/sub\u003e) was deconvoluted into reversing heat flow (\u003cb\u003eHF\u003c/b\u003e\u003csub\u003erev\u003c/sub\u003e) and non-reversing (\u003cb\u003eHF\u003c/b\u003e\u003csub\u003enon\u0026minus;rev\u003c/sub\u003e) components, under the assumption that structural changes minimally affect thermal kinetics. This analysis distinguishes reversible transitions involving changes in heat capacity, such as the glass transition, from non-reversible transitions driven by kinetic processes\u003csup\u003e\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e,\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u003c/sup\u003e. In the \u003cb\u003eHF\u003c/b\u003e\u003csub\u003etot\u003c/sub\u003e signals, all \u003cb\u003eC\u003c/b\u003e-MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs exhibited an initial endotherm desolvation event below 160\u0026deg;C. Following desolvation, a glass transition was observed in the \u003cb\u003eHF\u003c/b\u003e\u003csub\u003erev\u003c/sub\u003e traces of all samples, except \u003cb\u003eC\u003c/b\u003e-MgC\u003csub\u003e2\u003c/sub\u003eDC, denoted as \u003cem\u003eT\u003c/em\u003e\u003csub\u003eg\u003c/sub\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea, middle). Continued heating led to cold crystallisation at \u003cem\u003eT\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e, observed in the \u003cb\u003eHF\u003c/b\u003e\u003csub\u003enon\u0026minus;rev\u003c/sub\u003e signals for all samples except MgC\u003csub\u003e6\u003c/sub\u003eDC and MgC\u003csub\u003e7\u003c/sub\u003eDC (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea, right). The resulting \u003cb\u003ereC\u003c/b\u003e-MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDC phase exhibited crystalline structures distinct from the original \u003cb\u003eC\u003c/b\u003e-MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs, attributed to the rearrangements in the carboxylate binding modes due to the absence of coordinating water (Supplementary Fig.\u0026nbsp;6). Once crystallised, the \u003cb\u003ereC\u003c/b\u003e-MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs showed no further thermal transitions before decomposition (Supplementary Fig.\u0026nbsp;7).\u003c/p\u003e\u003cp\u003eIn the case of \u003cb\u003edesL\u003c/b\u003e-MgC\u003csub\u003e7\u003c/sub\u003eDC, an endothermic transition to a liquid crystal (\u003cb\u003eLC\u003c/b\u003e-) phase occurred at \u003cem\u003eT\u003c/em\u003e\u003csub\u003elc\u003c/sub\u003e, followed by melting at \u003cem\u003eT\u003c/em\u003e\u003csub\u003em\u003c/sub\u003e prior to decomposition\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e,\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u003c/sup\u003e. Upon quenching, the molten MgC\u003csub\u003e7\u003c/sub\u003eDC formed a different glassy state, \u003cb\u003emqG\u003c/b\u003e-, with a calorimetric \u003cem\u003eT\u003c/em\u003e\u003csub\u003eg\u003c/sub\u003e distinct from that of the \u003cb\u003edesG\u003c/b\u003e- phase, denoted as \u003cem\u003eT\u003c/em\u003e\u003csub\u003eg\u003c/sub\u003e\u003csup\u003emq\u003c/sup\u003e (Supplementary Fig.\u0026nbsp;8). Optical microscopy confirmed the glassy morphology of the \u003cb\u003edesG\u003c/b\u003e- and \u003cb\u003emqG\u003c/b\u003e- phases, whereas the \u003cb\u003eC\u003c/b\u003e- and \u003cb\u003edesC\u003c/b\u003e- phases retained a powdery crystalline form (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb and Supplementary Figs.\u0026nbsp;9 and 20). Although the \u003cb\u003edesG\u003c/b\u003e- phase could not be isolated and no calorimetric \u003cem\u003eT\u003c/em\u003e\u003csub\u003eg\u003c/sub\u003e was observed for MgC\u003csub\u003e2\u003c/sub\u003eDC, its \u003cb\u003ereC\u003c/b\u003e- phase exhibited a monolithic, glassy morphology, suggesting vitrification occurred during heating. This entire thermal evolution is summarised in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec. \u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003eH nuclear magnetic resonance (NMR) spectroscopy confirmed that the ligands retained their original structures within the polymeric network in all glassy states (Supplementary Fig.\u0026nbsp;10).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eMesophase-driven glass transition\u003c/b\u003e\u003c/p\u003e\u003cp\u003eMost hybrid glasses have shown a glass transition only in the second heating cycle because the original crystalline state lacks any glassy regions and vitrifies only after the first heating cycle. In contrast, MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDC series undergo both a calorimetric glass transition and cold crystallisation in the first DSC heating cycle even without pretreatment. This arises from the lability in carboxylate binding modes and flexibility in the aliphatic moieties. Based on the initial crystal structures of the \u003cb\u003eC\u003c/b\u003e-MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs, a plausible mechanism for the coordination structural rearrangements during desolvation can be proposed. In all \u003cb\u003eC\u003c/b\u003e-MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs, non-coordinated oxygen atoms are positioned 3.2\u0026ndash;3.4 \u0026Aring; from the metal nodes, which could allow them to form chelate bonds with the Mg centres upon desolvation. Subsequently, neighbouring oxygen atoms from other ligands (4.0\u0026ndash;4.2 \u0026Aring; away) could then approach the nodes. These potential movements would cause distortions in the alkyl-chain conformation. These rearrangements impose steric torsion on the ligands and introduce disorder into the hydrophobic domains as in semicrystalline polymers\u003csup\u003e\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e. The superlattice frameworks and the conformers in the aliphatic ligands drive both glass transition and cold crystallisation on heating. Above \u003cem\u003eT\u003c/em\u003e\u003csub\u003eg\u003c/sub\u003e, alkyl chains can adopt multiple conformations. Thus, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea, amorphous domains in the lamellar structure exhibit thermotropic mesomorphism with a mobile fluidic subphase\u003csup\u003e\u003cspan additionalcitationids=\"CR31\" citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e\u003c/sup\u003e, while SBUs remain intact owing to the rigid Mg\u0026ndash;L bonds. Cold crystallisation is driven by freely rotating chains, which enhance interchain interactions, leading to chain repacking in the organic substructure. In \u003cb\u003eC\u003c/b\u003e-MgC\u003csub\u003e2\u003c/sub\u003eDC and \u003cb\u003eC\u003c/b\u003e-MgC\u003csub\u003e4\u003c/sub\u003eDC, which feature 1D chain networks, desolvation transforms the crystals into an anti-parallel lamellar superlattice, where electrostatic repulsion between the opposing layers restricts the conformational rotation of the hydrocarbon spacers (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb). Although \u003cb\u003eC\u003c/b\u003e-MgC\u003csub\u003e3\u003c/sub\u003eDC has a 1D chain network, it also possesses a secondary network of hydrogen bonds between non-bonding carboxylates and coordinated water molecules. This creates a superlattice of alternating metal node and organic layers, analogous to the lamellar structure of the longer-chain CPs. Therefore, the thermal behaviour of MgC\u003csub\u003e3\u003c/sub\u003eDC is expected to more closely resemble that of the longer-chain CPs (\u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;5\u0026ndash;7) rather than the shorter-chain CPs (\u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;2 and 4).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eTo elucidate the mechanism of thermotropic behaviour of MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs featuring lamellar and 1D chain structures, ex-situ X-ray powder diffraction (XRPD) was conducted for MgC\u003csub\u003e5\u003c/sub\u003eDC and MgC\u003csub\u003e4\u003c/sub\u003eDC across their \u003cb\u003eC\u003c/b\u003e-, \u003cb\u003edesC\u003c/b\u003e-, \u003cb\u003edesG\u003c/b\u003e-, and \u003cb\u003ereC\u003c/b\u003e- phases. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea, the representative lamellar crystal, \u003cb\u003eC\u003c/b\u003e-MgC\u003csub\u003e5\u003c/sub\u003eDC, showed the disappearance of hydrophilic layers upon desolvation, resulting in reduced interlamellar spacing, evidenced by a shift in the first sharp diffraction peak (FSDP) from 2\u003cem\u003eθ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;6.18\u0026deg; to 8.42\u0026ndash;8.60\u0026deg; corresponding to a decrease in \u003cem\u003ed\u003c/em\u003e-spacing from 14.3 to 10.3\u0026ndash;10.5 \u0026Aring;. In contrast, \u003cb\u003eC\u003c/b\u003e-MgC\u003csub\u003e4\u003c/sub\u003eDC, representing a 1D chain structure, initially exhibited the higher-angle first diffraction peak (11.86\u0026deg;), corresponding to the shortest \u003cem\u003ed\u003c/em\u003e-spacing (7.6 \u0026Aring;) among the samples. Upon desolvation, the peak position shifted to lower angles, indicating an increased distance between SBUs, reaching 9.3\u0026ndash;12.7 \u0026Aring; across the post-desolvation phases. \u003cb\u003eC\u003c/b\u003e-MgC\u003csub\u003e2\u003c/sub\u003eDC exhibited a similar increase in the \u003cem\u003ed\u003c/em\u003e-spacing of its FSDP, while the thermal trend observed in the XRPD of \u003cb\u003eC\u003c/b\u003e-MgC\u003csub\u003e3\u003c/sub\u003eDC was more consistent with that of the longer-chain CPs (Supplementary Fig.\u0026nbsp;11). This suggests that the thermal transition mechanism is influenced not only by the linker chain length but also by the network structure of the initial \u003cb\u003eC\u003c/b\u003e- phase.\u003c/p\u003e\u003cp\u003eVariable-temperature, time-resolved in-situ XRPD measurements were performed on MgC\u003csub\u003e4\u003c/sub\u003eDC and MgC\u003csub\u003e5\u003c/sub\u003eDC at temperatures corresponding to their \u003cb\u003eC\u003c/b\u003e- (room temperature), \u003cb\u003edesC\u003c/b\u003e- (180\u0026deg;C) and \u003cb\u003edesL\u003c/b\u003e- (270\u0026deg;C) states (Supplementary Fig.\u0026nbsp;12\u0026ndash;14). The FSDP shift trends were consistent with the ex-situ XRPD data, but the in-situ analysis provided detailed insight into the mechanism of the thermal transition. For the lamellar \u003cb\u003eC\u003c/b\u003e-MgC\u003csub\u003e5\u003c/sub\u003eDC, the \u003cem\u003ed\u003c/em\u003e-spacing of the FSDP was observed to decrease gradually over time at 180\u0026deg;C, directly showing the removal of the hydrophilic layer. In contrast, \u003cb\u003eC\u003c/b\u003e-MgC\u003csub\u003e4\u003c/sub\u003eDC had already fully transformed to the \u003cb\u003edesC\u003c/b\u003e- phase upon reaching 180\u0026deg;C and thus showed no significant changes over time (Supplementary Fig.\u0026nbsp;13). This difference is likely because the confined hydrophilic layers in the lamellar structure of MgC\u003csub\u003e5\u003c/sub\u003eDC form a stronger hydrogen-bonded network, which delays the desolvation process compared to that of the initial 1D chain structure of \u003cb\u003eC\u003c/b\u003e-MgC\u003csub\u003e4\u003c/sub\u003eDC. At a higher temperature (270\u0026deg;C), the peaks for the \u003cb\u003edesL\u003c/b\u003e- phase were not only broader than those of the rigid \u003cb\u003edesC\u003c/b\u003e- phase but also exhibited significant fluctuations over time, confirming the high chain mobility of the supercooled liquid state. This suggests that both the glass transition and cold crystallisation are governed by the mobility of the hydrocarbon chains (Supplementary Fig.\u0026nbsp;14).\u003c/p\u003e\u003cp\u003ePair distribution function (PDF) analysis of synchrotron X-ray total scattering data revealed that long-range order was retained in \u003cb\u003edesG\u003c/b\u003e-MgC\u003csub\u003e5\u003c/sub\u003eDC, \u003cb\u003edesG\u003c/b\u003e-MgC\u003csub\u003e6\u003c/sub\u003eDC, and even in \u003cb\u003emqG\u003c/b\u003e-MgC\u003csub\u003e7\u003c/sub\u003eDC, with structural correlations persisting up to 30\u0026ndash;50 \u0026Aring;, whereas \u003cb\u003edesG\u003c/b\u003e-MgC\u003csub\u003e4\u003c/sub\u003eDC exhibited order only up to approximately 15 \u0026Aring; (Supplementary Fig.\u0026nbsp;15). In addition, short- and medium-range order (1.2\u0026ndash;5.0 \u0026Aring;) exhibited only minor changes in both \u003cb\u003edesG\u003c/b\u003e- and \u003cb\u003emqG\u003c/b\u003e- phases compared to the initial \u003cb\u003eC-\u003c/b\u003e state, suggesting that structural rearrangement was limited during either the mesophase glass transition or melting (Supplementary Fig.\u0026nbsp;16).\u003c/p\u003e\u003cp\u003eFourier-transform infrared (FTIR) spectroscopy was used to probe the further structural changes in the MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDC series (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb and Supplementary Fig.\u0026nbsp;17). Lower wavenumbers in the \u003cem\u003eν\u003c/em\u003e\u003csub\u003eas\u003c/sub\u003e(CH\u003csub\u003e2\u003c/sub\u003e) mode (around 2940 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) reflect an increased population of \u003cem\u003egauche\u003c/em\u003e defects corresponding to greater chain disorder\u003csup\u003e\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u003c/sup\u003e, while lower wavenumbers in the \u003cem\u003eν\u003c/em\u003e\u003csub\u003eas\u003c/sub\u003e(COO) mode (around 1540 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) qualitatively indicate strong Mg\u0026ndash;L bonds\u003csup\u003e\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e\u003c/sup\u003e. Desolvation caused a notable blueshift of the \u003cem\u003eν\u003c/em\u003e\u003csub\u003eas\u003c/sub\u003e(COO), confirming an alteration of the carboxylate binding mode. The changes in the \u003cem\u003eν\u003c/em\u003e\u003csub\u003eas\u003c/sub\u003e(CH₂) upon desolvation showed an odd\u0026ndash;even alternation, reflecting a carbon-number parity similar to that observed in \u003cem\u003en\u003c/em\u003e-alkane derivatives\u003csup\u003e\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e,\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e\u003c/sup\u003e. Specifically, the odd-numbered chains exhibited an increase in disorder, whereas the even-numbered chains showed a reduction in the number of \u003cem\u003egauche\u003c/em\u003e conformations. Notably, after mesophase vitrification, the \u003cem\u003eν\u003c/em\u003e\u003csub\u003eas\u003c/sub\u003e(COO) and \u003cem\u003eν\u003c/em\u003e\u003csub\u003eas\u003c/sub\u003e(CH\u003csub\u003e2\u003c/sub\u003e) in MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs both exhibited only minor changes compared to those observed during desolvation (Supplementary Table\u0026nbsp;3).\u003c/p\u003e\u003cp\u003eThese odd-even trends reflect a competition between the vdW stabilisation of the hydrocarbon chains and electrostatic repulsion of the terminal carboxyl groups\u003csup\u003e\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e,\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e\u003c/sup\u003e. In the odd-numbered chains, an \u003cem\u003eall-trans\u003c/em\u003e conformation forces the carboxylate groups into a \u003cem\u003ecis\u003c/em\u003e-like arrangement, inducing electrostatic repulsion. This inherent instability provides a driving force for the chains to reconfigure and increase their disorder when the coordination state is rearranged during desolvation. Conversely, the even-numbered chains can adopt a more ordered arrangement with fewer \u003cem\u003egauche\u003c/em\u003e conformations, as their \u003cem\u003eall-trans\u003c/em\u003e state places the carboxylates in a stable, \u003cem\u003etrans\u003c/em\u003e-like arrangement. This model helps to account for the observed FTIR trends in the various states of MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs. The desolvation process for this system induces large spectroscopic shifts and a pronounced odd-even effect because it involves significant atomic rearrangement, such as the translational motion of carbonyl carbons\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e,\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e\u003c/sup\u003e. In contrast, the glass transition of MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs involves only minor interaction changes. This implies that the glass transition is driven by smaller-scale motions, such as the mobility of the hydrocarbon chains, rather than by changes in coordination state or the cleavage of Mg-L bonds. PDF analysis also showed that the Mg⋯Mg correlations at 8\u0026ndash;15 \u0026Aring; produced a sharp peak in odd-numbered glasses, whereas even-numbered glasses exhibited broad peaks in that region, implying greater positional distortion of Mg and hence higher chain mobility in the even-numbered series during vitrification (Supplementary Fig.\u0026nbsp;16).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eCold crystallisation of \u003cb\u003edesL\u003c/b\u003e-MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs exhibited comparable FTIR trends, indicating that the main mechanism is the reordering of chains to maximise hydrophobic interactions, as evidenced by the \u003cem\u003eν\u003c/em\u003e\u003csub\u003eas\u003c/sub\u003e(CH\u003csub\u003e2\u003c/sub\u003e) redshift (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb)\u003csup\u003e\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e,\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e\u003c/sup\u003e. Additionally, partial crystallisation was observed in \u003cb\u003edesL\u003c/b\u003e-MgC\u003csub\u003e6\u003c/sub\u003eDC under applied shear stress or prolonged heating, despite the absence of a distinct calorimetric \u003cem\u003eT\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e, supporting the mechanism whereby conformational chain mobility governs the thermal behaviours in MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs (Supplementary Fig.\u0026nbsp;18)\u003csup\u003e\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e,\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e\u003c/sup\u003e. The \u003cb\u003eC\u003c/b\u003e-, \u003cb\u003edesC\u003c/b\u003e- and \u003cb\u003edesG\u003c/b\u003e- phases of MgC\u003csub\u003e6\u003c/sub\u003eDC and MgC\u003csub\u003e7\u003c/sub\u003eDC showed similar XRPD and FTIR trends to those of MgC\u003csub\u003e5\u003c/sub\u003eDC, while MgC\u003csub\u003e2\u003c/sub\u003eDC behaved similarly to MgC\u003csub\u003e4\u003c/sub\u003eDC (Supplementary Figs.\u0026nbsp;11 and 17).\u003c/p\u003e\u003cp\u003e\u003cb\u003eThermomechanical Properties\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe thermal behaviour trends and mechanical properties of the MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs varied with the length of the alkyl chain (Figs.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e and \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). The calorimetric transition temperatures (\u003cem\u003eT\u003c/em\u003e\u003csub\u003ed\u003c/sub\u003e, \u003cem\u003eT\u003c/em\u003e\u003csub\u003eg\u003c/sub\u003e, and \u003cem\u003eT\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e) were identified by TGA and TMDSC and were observed to decrease as \u003cem\u003en\u003c/em\u003e increased (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea). \u003cem\u003eT\u003c/em\u003e\u003csub\u003ed\u003c/sub\u003e decreased significantly from \u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;2\u0026ndash;4 and then showed little variation from \u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;4\u0026ndash;7. This observation agrees with previous reports\u003csup\u003e\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e\u003c/sup\u003e that the influence of the alkyl chain on the carboxylate group became smaller after \u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;4. Considering the reported trend in ligand p\u003cem\u003eK\u003c/em\u003e\u003csub\u003ea\u003c/sub\u003e values, we infer that the \u003cem\u003eT\u003c/em\u003e\u003csub\u003ed\u003c/sub\u003e values were primarily influenced by the strength of the Mg\u0026ndash;O bonds\u003csup\u003e\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e\u003c/sup\u003e. \u003cem\u003eT\u003c/em\u003e\u003csub\u003eg\u003c/sub\u003e decreased monotonically, mirroring the trend in organic polymers as spacer length increases\u003csup\u003e\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e,\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e\u003c/sup\u003e. Each added methylene unit acts as a flexible hinge, increasing the conformational freedom of the chains and lowering the energy barrier for segmental motion. The absence of an odd-even effect in \u003cem\u003eT\u003c/em\u003e\u003csub\u003eg\u003c/sub\u003e indicates that the glass transition in MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs is dictated primarily by vdW forces rather than by the odd-even effects seen in ionic glasses, reinforcing the proposed mechanism for their glass transition\u003csup\u003e\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e,\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eThermodynamic parameters derived from DSC measurements (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eb) and principles of polymer physics were used to explain the trends in \u003cem\u003eT\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e. The crystallisation enthalpy and entropy (Δ\u003cem\u003eH\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e and Δ\u003cem\u003eS\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e) represent the differences in energy and accessible chain conformations between the \u003cb\u003edesL-\u003c/b\u003e and \u003cb\u003ereC\u003c/b\u003e- states, respectively. Δ\u003cem\u003eH\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e followed the order MgC\u003csub\u003e3\u003c/sub\u003eDC\u0026thinsp;\u0026gt;\u0026thinsp;MgC\u003csub\u003e2\u003c/sub\u003eDC\u0026thinsp;\u0026gt;\u0026thinsp;MgC\u003csub\u003e5\u003c/sub\u003eDC\u0026thinsp;\u0026gt;\u0026thinsp;MgC\u003csub\u003e4\u003c/sub\u003eDC. For chains of length \u003cem\u003en\u003c/em\u003e\u0026thinsp;\u0026le;\u0026thinsp;3, the Δ\u003cem\u003eH\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e of MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDC exceeded the standard molar fusion enthalpies of the corresponding H₂C\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDC ligands\u003csup\u003e\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e\u003c/sup\u003e, but the trend reversed for n\u0026thinsp;\u0026ge;\u0026thinsp;4. Since the enthalpy of H₂C\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDC arises mainly from the breaking of hydrogen bonds, the higher Δ\u003cem\u003eH\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e of MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDC with \u003cem\u003en\u003c/em\u003e\u0026thinsp;\u0026le;\u0026thinsp;3 chains implies that electrostatic stabilisation dominated during crystallisation, whereas for \u003cem\u003en\u003c/em\u003e\u0026thinsp;\u0026ge;\u0026thinsp;4 chains vdW interactions prevailed. The order of Δ\u003cem\u003eS\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e for the MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs was the same as that of Δ\u003cem\u003eH\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e. Except for MgC\u003csub\u003e3\u003c/sub\u003eDC, all MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs exhibited lower Δ\u003cem\u003eS\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e values than the standard molar fusion entropies of \u003cem\u003en\u003c/em\u003e-alkanes of equivalent chain length, (CH\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003e(CH\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e. Notably, MgC\u003csub\u003e4\u003c/sub\u003eDC and MgC\u003csub\u003e5\u003c/sub\u003eDC displayed Δ\u003cem\u003eS\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e values of 22.58 and 33.02 J\u0026middot;mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u0026middot;K\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, respectively. The difference between these two values (10.44 J\u0026middot;mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u0026middot;K\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) falls within the typical range of conformational entropy contributed by a single methylene group (7\u0026ndash;12 J\u0026middot;mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u0026middot;K\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)\u003csup\u003e16,48\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eTaken together, the observed trend in Δ\u003cem\u003eS\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e and the inverse \u003cem\u003eT\u003c/em\u003e\u003csub\u003eg\u003c/sub\u003e-\u003cem\u003en\u003c/em\u003e relationship are characteristic of a conformationally disordered crystal (condis crystal), a type of mesophase. A condis crystal is a state that possesses dynamic disorder arising from the internal conformational disorder of its components\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e. Consequently, its thermodynamic parameters are strongly correlated with the chain length, \u003cem\u003en\u003c/em\u003e, as seen in this case. This model provides a framework for explaining several key experimental observations. For instance, the absence of a detectable \u003cem\u003eT\u003c/em\u003e\u003csub\u003eg\u003c/sub\u003e in MgC\u003csub\u003e2\u003c/sub\u003eDC can be attributed to the limited conformational states of its short \u003cem\u003en\u003c/em\u003e-butane-like chain (only two non-equivalent conformers), which allows its glass transition to occur too rapidly for calorimetric detection. Conversely, for the longer chains (\u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;4\u0026ndash;7), the exponential growth in accessible conformers\u003csup\u003e\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e\u003c/sup\u003e increases the activation energy and slows the crystallisation kinetics\u003csup\u003e\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e,\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e\u003c/sup\u003e. This slowing of the ordering process explains both the higher \u003cem\u003eT\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e of MgC\u003csub\u003e5\u003c/sub\u003eDC compared to MgC\u003csub\u003e4\u003c/sub\u003eDC, and the complete disappearance of a calorimetric \u003cem\u003eT\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e for the longest-chain members, MgC\u003csub\u003e6\u003c/sub\u003eDC and MgC\u003csub\u003e7\u003c/sub\u003eDC\u003csup\u003e\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e\u003c/sup\u003e. The enhanced stability in the \u003cb\u003edesL\u003c/b\u003e- and \u003cb\u003edesG\u003c/b\u003e- states for these longer spacers is driven by greater interchain forces and increased molecular entanglement\u003csup\u003e\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e,\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e\u003c/sup\u003e. Taken together, these results indicate that MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs crystallise via a mesophase-mediated pathway governed by the reordering of their aliphatic chains, in a manner consistent with established polymer crystallisation models\u003csup\u003e\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e,\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe elastic modulus (\u003cem\u003eE\u003c/em\u003e) and hardness (\u003cem\u003eH\u003c/em\u003e) for \u003cb\u003edesG\u003c/b\u003e-MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDC (\u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;4\u0026ndash;6) and \u003cb\u003emqG\u003c/b\u003e-MgC\u003csub\u003e7\u003c/sub\u003eDC were measured by nanoindentation. The \u003cem\u003eE\u003c/em\u003e and \u003cem\u003eH\u003c/em\u003e were calculated from the load-depth curves of glass samples (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ea and Supplementary Table\u0026nbsp;5). All samples were confirmed as amorphous by XRPD and exhibited plastic deformation under indentation. However, \u003cb\u003edesG\u003c/b\u003e-MgC\u003csub\u003e4\u003c/sub\u003eDC presented propagated radial cracks, indicating the formation of a crystalline region during vitrification (Supplementary Fig.\u0026nbsp;19)\u003csup\u003e\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e\u003c/sup\u003e. This semicrystalline state increased \u003cem\u003eE\u003c/em\u003e through denser packing within its crystalline domains but reduced \u003cem\u003eH\u003c/em\u003e due to inefficient stress transfer in the anti-parallel lamellar superlattice\u003csup\u003e\u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e58\u003c/span\u003e\u003c/sup\u003e. Hence, \u003cb\u003edesG\u003c/b\u003e-MgC\u003csub\u003e4\u003c/sub\u003eDC exhibited higher \u003cem\u003eE\u003c/em\u003e and lower \u003cem\u003eH\u003c/em\u003e (19.50 and 0.85 GPa) than \u003cb\u003edesG\u003c/b\u003e-MgC\u003csub\u003e5\u003c/sub\u003eDC (17.48 and 0.92 GPa), which had a fully amorphised network. Notably, \u003cb\u003edesG\u003c/b\u003e-MgC\u003csub\u003e6\u003c/sub\u003eDC exhibited enhanced \u003cem\u003eE\u003c/em\u003e and \u003cem\u003eH\u003c/em\u003e (58.09 and 2.19 GPa) compared to the isoreticular \u003cb\u003edesG\u003c/b\u003e-MgC\u003csub\u003e5\u003c/sub\u003eDC, with values exceeding those of cement-based materials and reported organic crystals\u003csup\u003e\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e,\u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e60\u003c/span\u003e\u003c/sup\u003e. This implies a large amount of chain interlocking within the intralamellar space between SBUs (\u0026asymp;\u0026thinsp;12 \u0026Aring;), amplifying interchain forces beyond those in entangled organic polymers\u003csup\u003e\u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e61\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eIn contrast, \u003cb\u003emqG\u003c/b\u003e-MgC\u003csub\u003e7\u003c/sub\u003eDC exhibited significantly lower \u003cem\u003eE\u003c/em\u003e and \u003cem\u003eH\u003c/em\u003e (2.60 and 0.10 GPa) than the \u003cb\u003edesG\u003c/b\u003e-MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDCs. This difference originates from the distinctive multi-step melting process of MgC\u003csub\u003e7\u003c/sub\u003eDC. Prior to melting, an endothermic transition at \u003cem\u003eT\u003c/em\u003e\u003csub\u003elc\u003c/sub\u003e suggests a transition from the condis phase to a liquid crystal phase. This phase transition is supported by ex-situ XRPD data showing that a lamellar order peak (2\u003cem\u003eθ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;5.50\u0026deg;, \u003cem\u003ed\u003c/em\u003e\u0026thinsp;=\u0026thinsp;16.1 \u0026Aring;) temporarily reappears in the initial stage of the \u003cb\u003eLC\u003c/b\u003e- phase, but only this long-range order disappears over time (Supplementary Fig.\u0026nbsp;18). In addition, upon melting, Mg\u0026ndash;L bonds dissociated, as evidenced by weight loss and the formation of uncoordinated carbonyl at \u003cem\u003eT\u003c/em\u003e\u003csub\u003em\u003c/sub\u003e (Supplementary Figs.\u0026nbsp;3 and 16). The sample also exhibited browning post-melt, which indicated partial decomposition of the ligand (Supplementary Fig.\u0026nbsp;20). Thus, the combination of interlamellar disorder induced in the \u003cb\u003eLC\u003c/b\u003e- phase and the partial disassembly of the rigid SBU backbones during melting increases segmental mobility in the melt-quenched glass, resulting in its softer mechanical properties (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eb).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eGlass transition and melting behaviours in MOFs and CPs have been interpreted within two frameworks based on inorganic glasses or organic polymers. The thermal transitions of MgC\u003cem\u003e\u003csub\u003en\u003c/sub\u003e\u003c/em\u003eDCs illustrate both viewpoints and highlight the link between coordination polymers and organic polymers in glass formation. The lamellar structures of \u003cstrong\u003e\u003cem\u003eC\u003c/em\u003e\u003c/strong\u003e-MgC\u003cem\u003e\u003csub\u003en\u003c/sub\u003e\u003c/em\u003eDCs mirror a network of organic polymers. Ligands serve as spacers through covalent and coordination bonds while SBUs form rigid backbones similar to the main chains of bottlebrush polymers\u003csup\u003e63\u003c/sup\u003e. A key distinction lies in electrostatic properties. Organic polymers feature hydrocarbon backbones and side chains whereas SBUs and ligands in CPs carry opposing electrostatic charges. This contrast creates crystallographically distinct interaction spaces that periodically enhance nanoscale chain rotation and drive macroscopic changes in viscosity and vitrification. In a manner akin to crosslinked polymers, SBUs dissociate above \u003cem\u003eT\u003c/em\u003e\u003csub\u003em\u003c/sub\u003e, which increases segmental mobility and yields softer, more stretchable glass networks reminiscent of an elastomer\u003csup\u003e64\u003c/sup\u003e. Melting was observed only in MgC\u003csub\u003e7\u003c/sub\u003eDC, which suggests that longer carbon chains supply greater entropy of fusion and supports the hypothesis that the rotamer population governs framework meltability.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn summary, we have developed a route to vitrify CPs by forming a mesophase with aliphatic dicarboxylate ligands under thermal desolvation. This mesophase arises from the unique properties of aliphatic dicarboxylates. Desolvation creates partially disordered networks due to versatile binding modes of the carboxylate groups. Within this mesophase, the rotatable C–C bonds of the hydrocarbon chains allow a mobile, supercooled liquid phase to form upon heating above the \u003cem\u003eT\u003c/em\u003e\u003csub\u003eg\u003c/sub\u003e, which then vitrifies into a glass upon subsequent cooling. Notably, the mesophase-derived glasses exhibited hard mechanical properties while the melt-quenched glasses were comparatively softer due to different chain packing arrangements, with the former resembling semicrystalline polymers. This work broadens strategies for hybrid glass fabrication and provides a pathway to design vitrifiable coordination networks using insights from the organic polymer and liquid crystal fields.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eMechanical properties measurement\u003c/p\u003e\n\u003cp\u003eSamples were placed on glass slides and vitrified under argon at 5 K above their respective \u003cem\u003eT\u003c/em\u003e\u003csub\u003eg\u003c/sub\u003e or \u003cem\u003eT\u003c/em\u003e\u003csub\u003em\u003c/sub\u003e. They were held at this temperature for 15 minutes and subsequently quenched in room air, with argon flow maintained to prevent oxidative interference. All\u0026nbsp;\u003cstrong\u003e\u003cem\u003edesG\u003c/em\u003e\u003c/strong\u003e- samples were measured in their as-prepared state without further treatment, whereas\u0026nbsp;\u003cstrong\u003e\u003cem\u003emqG\u003c/em\u003e\u003c/strong\u003e-MgC\u003csub\u003e7\u003c/sub\u003eDC was polished using 600-grit sandpaper and rinsed with acetone (Supplementary Fig 16). Nanoindentation was performed using an Anton-Paar nanoindenter with a Berkovich tip. \u003cem\u003eE\u003c/em\u003e and \u003cem\u003eH\u003c/em\u003e were extracted from load–depth curves using the Oliver–Pharr method. Maximum loads were set at 5 mN for\u0026nbsp;\u003cstrong\u003e\u003cem\u003emqG\u003c/em\u003e\u003c/strong\u003e-MgC\u003csub\u003e7\u003c/sub\u003eDC, 15 mN for\u0026nbsp;\u003cstrong\u003e\u003cem\u003edesG\u003c/em\u003e\u003c/strong\u003e-MgC\u003csub\u003e4\u003c/sub\u003eDC and MgC\u003csub\u003e5\u003c/sub\u003eDC, and 80 mN for\u0026nbsp;\u003cstrong\u003e\u003cem\u003edesG\u003c/em\u003e\u003c/strong\u003e-MgC\u003csub\u003e6\u003c/sub\u003eDC. Values near the maximum penetration depth were taken as the representative \u003cem\u003eE\u003c/em\u003e and \u003cem\u003eH\u003c/em\u003e for each sample.\u0026nbsp;\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eData availability\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data that support the findings of this work are presented in the Supplementary Information. Additional data are available on request from the corresponding authors.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work supported by the National Research Foundation of Korea (NRF) through the Nano \u0026amp; Material Technology Development Program funded by the Ministry of Science and ICT (Grant No. RS-2024-00408180 to E.-c.J.) and through NRF grants (NRF- 2020R1A2C3008908 and 2021R1A6A10039823 to H.R.M.). This work also supported by a Korea Basic Science Institute (National Research Facilities and Equipment Center) grant funded by the Ministry of Education (2020R1A6C101B194 to H.R.M.). The synchrotron radiation experiments were performed at BL04B2 (Proposal No. 2024B1316) and BL13XU (Proposal No. 2024B1639) of SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;M.K. and H.R.M. conceived the idea for the project. M.K. designed the experiments and performed the synthesis. M.K. and Y.L. conducted characterisation of the thermal transitions and their results in CPs. H.-y.J. analysed the mechanical properties of the glassy CPs under direction of E.-c.J.. M.K. and H.R.M. wrote the paper, and all the authors contributed to preparing the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eDebenedetti, P. 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H. \u003cem\u003eet al.\u003c/em\u003e Educational series: characterizing crosslinked polymer networks. \u003cem\u003ePolym. Chem.\u003c/em\u003e \u003cstrong\u003e15\u003c/strong\u003e, 219\u0026ndash;247 (2024).\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"nature-portfolio","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Nature Portfolio","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"ejp","reportingPortfolio":"","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-7266933/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7266933/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eHybrid glasses derived from coordination polymers (CPs) promise a fusion of processability and structural functionality, yet their formation is fundamentally limited by poor thermal stability and high melting points. Here, we demonstrate a mesophase-mediated vitrification mechanism in a series of magnesium-based CPs (MgC\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003eDC, \u003cem\u003en\u003c/em\u003e = 2–7) featuring aliphatic dicarboxylate linkers. Upon thermal desolvation, these frameworks transition into a mesomorphic state that retains coordination integrity while inducing conformational disorder in the organic substructure. This intermediate state enables a direct glass transition without requiring full melting. The resulting glasses exhibit distinct calorimetric transitions and tunable mechanical properties governed by chain length and topology. Furthermore, only the longest-chain member (\u003cem\u003en\u003c/em\u003e = 7) is also capable of conventional melting after forming the mesophase, leading to a melt-quenched glass with lower mechanical stiffness due to partial disruption of its metal-organic backbone. Spectroscopic and structural analyses reveal that mesophase vitrification proceeds via unlocking rotational freedom in the hydrocarbon chains, drawing strong parallels to semicrystalline polymer behaviour. These findings establish a design strategy for vitrifiable coordination networks by integrating principles from polymer dynamics and mesomorphism.\u003c/p\u003e","manuscriptTitle":"Mesophase-induced Vitrification in Coordination Polymers via Aliphatic Chain Dynamics","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-08-18 06:19:31","doi":"10.21203/rs.3.rs-7266933/v1","editorialEvents":[],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"nature-communications","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"NCOMMS","sideBox":"Learn more about [Nature Communications](http://www.nature.com/ncomms/)","snPcode":"","submissionUrl":"https://mts-ncomms.nature.com/","title":"Nature Communications","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature Communications","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"1619e830-e105-459e-a746-df117514f0ff","owner":[],"postedDate":"August 18th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":53171668,"name":"Physical sciences/Chemistry/Materials chemistry/Metal\u0026#x2013;organic frameworks"},{"id":53171669,"name":"Physical sciences/Chemistry/Inorganic chemistry/Solid-state chemistry"}],"tags":[],"updatedAt":"2026-04-28T14:26:21+00:00","versionOfRecord":[],"versionCreatedAt":"2025-08-18 06:19:31","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7266933","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7266933","identity":"rs-7266933","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}