Diazine Endo-Functionalized Tetraphenylethylene-Based Cyclo[6]arenes for Molecular Recognition in Both Solution and Aggregate States

Diazine Endo-Functionalized Tetraphenylethylene-Based Cyclo[6]arenes for Molecular Recognition in Both Solution and Aggregate States | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL Aggregate This is a preprint and has not been peer reviewed. Data may be preliminary. 22 July 2025 V1 Latest version Share on Diazine Endo-Functionalized Tetraphenylethylene-Based Cyclo[6]arenes for Molecular Recognition in Both Solution and Aggregate States Authors : Nan Pan , Shuhong Liu , Weichen Tan , Linbin Yao , Jialin Xie 0009-0000-1656-7720 [email protected] , Kelong Zhu , and Chunman Jia Authors Info & Affiliations https://doi.org/10.22541/au.175314616.66920545/v1 Published Aggregate Version of record Peer review timeline 322 views 190 downloads Contents Abstract Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract Merging tetraphenylethylene (TPE) into cyclic skeletons endows fluorescent sensing capabilities for pillar[6]arenes aggregates, but results in losing their host–guest recognition function in dilute solutions. Inspired by natural enzymes, here we describe a series of TPE-based cyclo[6]arenes (termed TPz , TDz , and TTz ) with endo -functionalized cavities containing inward-directed diazine motifs (pyrazine, pyridazine, and phthalazine) that act as hydrogen-bond acceptor sites. Combining electrostatic potential analysis and host–guest binding studies reveal that subtle variations in these diazine motifs substantially affect charge distribution and hydrogen-bond interactions within the internal microenvironment. These differences translate into disparate host–guest affinities, with TTz exhibiting the optimal performance. Unlike TPz which recognizes guests only in aggregate states, 1,2-diazine modified TDz and TTz possess dual-state recognition functionality. They enable size-selective binding for cationic guests in dilute solutions and sensitive fluorescence detection of nitrophenol pollutants in aggregate states through a photo-induced electron transfer-driven static quenching mechanism. This study underscores the potential of 1,2-diazine motifs as transformative hydrogen-bond acceptors for biomimetic host models with emergent properties. Diazine Endo -Functionalized Tetraphenylethylene-Based Cyclo[6]arenes for Molecular Recognition in Both Solution and Aggregate States Nan Pan, 1 Shuhong Liu, 1 Weichen Tan, 1 Linbin Yao, 1 Jialin Xie,* 1 Kelong Zhu, 2 and Chunman Jia* 1,3 1 N. Pan, S. Liu, W. Tan, Dr. L. Yao, Dr. J. Xie, Prof. Dr. C. Jia Hainan Provincial Key Laboratory of Fine Chem, School of Chemistry and Chemical Engineering, Hainan University, Haikou 570228, China E-mail: [email protected] ; [email protected] 2 Prof. Dr. K. Zhu School of Chemistry, Sun Yat-Sen University, Guangzhou 510275, China 3 Prof. Dr. C. Jia Analysis and Testing Center, Hainan University, Haikou 570228, China Keywords: cyclo[6]arenes, diazine, endo -functionalized cavity, hydrogen bonds, m olecular recognition Abstract : Merging tetraphenylethylene (TPE) into cyclic skeletons endows fluorescent sensing capabilities for pillar[6]arenes aggregates, but results in losing their host – guest recognition function in dilute solutions. Inspired by natural enzymes, here we describe a series of TPE-based cyclo[6]arenes (termed TPz , TDz , and TTz ) with endo -functionalized cavities containing inward-directed diazine motifs (pyrazine, pyridazine, and phthalazine) that act as hydrogen-bond acceptor sites. Combining electrostatic potential analysis and host – guest binding studies reveal that subtle variations in these diazine motifs substantially affect charge distribution and hydrogen-bond interactions within the internal microenvironment. These differences translate into disparate host – guest affinities, with TTz exhibiting the optimal performance. Unlike TPz which recognizes guests only in aggregate states, 1,2-diazine modified TDz and TTz possess dual-state recognition functionality. They enable size-selective binding for cationic guests in dilute solutions and sensitive fluorescence detection of nitrophenol pollutants in aggregate states through a photo-induced electron transfer-driven static quenching mechanism. This study underscores the potential of 1,2-diazine motifs as transformative hydrogen-bond acceptors for biomimetic host models with emergent properties. 1. Introduction Molecular recognition is fundamental to both supramolecular chemistry and biological processes. [1–3] Currently, macrocyclic chemistry and aggregation-induced emission (AIE) are advancing synergistically toward innovative endeavors. [4–6] Notably, macrocycles functionalized with tetraphenylethylene (TPE) within cyclic skeletons ingeniously combine host properties with AIE activity, enabling versatile recognition applications such as chiral recognition, chemical sensing, and light-harvesting systems. [7–14] Building on extensive research and excellent molecular recognition capabilities of pillar[ n ]arenes, TPE-embedded pillar[ n ]arenes with diverse topologies have recently achieved remarkable strides. [15– 20] However, in stark contrast to TPE-embedded pillar[5]arenes, reported TPE-embedded pillar[6]arenes exhibit host – guest interactions exclusively in aggregate states, with negligible activity in dilute solutions (isolated state). This behavior can be interpreted as a “twisted and flattened” cavity conformation partially filled by alkyl chains, a structural compromise arising from the ethylenic bridge and lower structural rigidity (Figure 1A) . [18– 20] Although simplifying alkyl chains could enlarge the cavity space, it would diminish the internal electron-rich environment, rendering it likewise unfavorable for guest binding, as observed in TPE-embedded [1 5 ]paracyclophane by Hu et al . [21] Consequently, structural modification of TPE-embedded pillar[6]arenes for effective dual-state recognition in both dilute solutions and aggregate states remains an unresolved challenge. In natural enzymes, the active recognition sites are often modified by amino acid residues capable of forming hydrogen bonds (H-bonds), contributing to high affinity and precise target binding. [ 22] Statistically, approximately 89% of fragment­­–pocket complexes in biological systems rely on H-bond interactions for stabilization. [ 2 3] Drawing inspiration from the construction and recognition mechanisms of enzyme binding pockets , a biomimetic “ endo -functionalized cavity” strategy has emerged. This strategy involves strategically positioning polar functional groups within cavities to promote H-bond formation, thereby mimicking the internal microenvironment of bioreceptors. [ 24–26] Following this concept, various preorganized biomimetic receptors with unique topologies have been created. [ 27–42] For example, Davis et al . customized a series of temple-shaped synthetic lectins utilizing lactam or urea groups as H-bond donors, which feature multiple inward-directed N – H sites within cavities for carbohydrate recognition. [ 24,31] Similarly, Jiang et al . developed naphthotubes with diverse types of recognition sites, including ethers, esters, and imines as H-bond acceptors, in addition to lactams and ureas. [ 25,28] To address this challenge, as illustrated in Figure 1B, we devised three structurally similar TPE-based cyclo[6]arenes, designated TPz , TDz , and TTz , each decorated with diverse diazine motifs, either 1,4-diazine (pyrazine) or 1,2-diazines (pyridazine or phthalazine). By purely altering the diazine motifs, the binding potency could be modulated without compromising recognition selectivity. Structure – activity relationship analysis revealed that TTz exhibits the highest dual-state recognition affinity, effectively binding cationic guests in dilute solutions and nitrophenols in aggregate states. Diazines containing two sp 2 N atoms were selected for distinctive structural attributes: ( i ) They possess modest basicity relative to pyridine (p K a = 5.2), with phthalazine being the strongest at p K a = 3.17. [43] ( ii ) The adjacent lone-pair effect confers 1,2-diazines dual H-bond acceptor functionality with H-bond acceptor potential comparable to that of pyridine. [43] ( iii ) The lone-pair electron repulsion between N and O atoms can drive N atoms inwardly directed, potentially forming preorganized cavities with endohedral sites to enhance binding strength. [44] 2. Results and discussion 2.1. Preparation and characterization Synthesis of these macrocycles, as illustrated in Figure 2, was achieved in moderate yields (26% to 32%) by a facile one-step cyclocondensation of TPE-derivative diphenols with the corresponding dichlorodiazines, and avoiding indirect tetrazine conversions. [45] The target macrocycles were fully characterized using NMR and high-resolution mass spectrometry (HRMS), with proton signals assigned via 2D-NMR (Figures S6–S17). Calculated electrostatic potential (ESP) maps revealed that the negative electrostatic potentials inside these electron-rich cavities are concentrated around the N atoms, with increasing electron-density from TPz to TTz (Figure 2 down). What is more, as unique to diazine motifs and anticipated from ESP analysis, the aromatic signal for H a located within cavities exhibited a gradual downfield chemical shift correlating with the enhanced H-bond acceptor capability . Particularly, the signals for ortho -aromatic protons H a and H b in TTz even overlapped, suggesting the presence of intramolecular H-bond interactions, which should be more attractive to H-bond donor species. The endo -functionalized macrocycles with open-cavity structures were definitively validated through single-crystal X-ray diffraction analysis (Figure 3 and Tables S2, S3). As envisioned, the diazine functional motifs were observed to be procumbent with N atoms oriented toward the interior cavities, but different diazine motifs subtly influenced cavity geometry. In THF-grown crystallites, TPz’s cavity was filled up by one THF molecule, with dihedral angles of 29.3° and 32.6° between its pyrazine motifs and cavity plane (defined by the O and sp 2 C atoms). Conversely, those in TDz were smaller at 22.2°, with two THF molecules suspended on either side of its cavity by multiple intermolecular C–H···N bonds. Although TTz shares a similar backbone with TDz, its phthalazine motifs were nearly parallel to the well-defined cavity, with a 7.3 Å distance between opposite equatorial N atoms. Such a difference may be attributed to different solvent inclusion or crystal packing, such as the two-sided THF complexation in TDz influencing stericity. Besides, the smaller dihedral angle of functional motifs, the larger dihedral angle of phenyl rings within cavity. A severely disordered CH 3 CN molecule was trapped inside TTz cavity, with several C–H···N interactions at bond lengths of 2.9 to 3.1 Å detected between its inward-facing N atom and methyl protons of CH 3 CN. Furthermore, these macrocycles adopted layered packing arrangements stabilized by numerous C–H···π noncovalent interactions in both intra- and inter-layers, promoting their fluorescence emission in the aggregate or solid states (discussed below). Despite the shallow cavities depth of only 3.4 Å, these crystalline solvates supported that buried binding sites provide additional noncovalent interactions within cavities to encapsulate guests, making them promising supramolecular hosts with engineered recognition pockets . All three macrocycles are excellent AIE-active luminogens with similar photophysical characteristics (Figures S63–S66). Among them, macrocycle TTz exhibited superior optical performance under identical conditions, with a distinctly red-shifted emission wavelength to 461 nm and an absolute quantum yield of Φ F = 30.1% for its solid powder (Figure 4B and Table S1). Taking it as a representative example, its pure THF solution (10 μM) displayed a maximum absorption band centered at 320 nm, but only faint emission was detected at 477 nm (Figure 4A), likely due to non-radiative decay associated with intramolecular motions of the pendant phenyl rings. As water was gradually added as an anti-solvent (Figure 4C and 4D), the emitted blue fluorescence intensified with molecular aggregation. It fluctuated slightly at water fraction ( f w , vol%) below 50%, and then steadily enhanced until reaching a maximum at f w = 95%. At this point, the emission wavelength underwent a 21 nm blue shift to 456 nm, representing a 55-fold enhancement compared to that in pure THF solution. Additionally, dynamic light scattering (DLS) confirmed the formation of aggregates with an average diameter of about 154.6 nm at this water fraction, and a corresponding broad-tail phenomenon was observed in the UV–vis spectrum (Figure S66). 2.2. Molecular recognition in dilute solutions To evaluate and compare the contributions of buried binding sites for host–guest recognition, a series of cationic molecules with diverse geometries were selected as model guests based on H-bond complementarity (Figure 5). As proposed, the initial NMR experiments with TPz revealed negligible chemical shift changes, indicating its poor binding affinity to these guests (Figures S18–S23). In contrast, TTz showed clear host–guest interactions, characterized by faster exchange rates than the NMR timescale between complex and free species, as well as cavity-induced shielding effects leading to upfield shifts in all guest signals (Figures S42–S62). Detailed NMR analysis indicated that the impact on TTz proton H a varied with guest size. Specifically, the deshielding effects from smaller alkyl guests G5 or G6 caused a slightly downfield shift on this signal, whereas bulkier guests like G3 or G4 induced an unusual upfield shift (Figure 5A). This phenomenon might be jointly caused by varied degrees of cavity expansion upon encapsulating guests, which weakens intramolecular H-bonds, as well as differential deshielding effects exerted by the guests. The binding affinities of TTz for these guests were further quantified by non-linear fitting of titration data with 1:1 stoichiometry mode, revealing a well size-dependent correlation (Figure 5B). Among them, TTz⊃G5 complex showed the strongest affinity with an association constant ( K a ) of 4517 ± 56 M −1 . [46] Accordingly, HRMS analysis detected characteristic signal peaks for TTz⊃G2, TTz⊃G4, and TTz⊃G5 complexes (Figures S48, S55, and S57). Similarly, macrocycle TDz also possesses binding capacity toward these model guests but with weaker affinity (Figures S24–S41). It is noteworthy that its proton H a NMR signal all shifted downfield upon binding guests G3–G6. Consistent with the ESP theoretical models, increased electron-density within macrocycle cavity was reflected by an enhanced binding affinity in the order TPz < TDz < TTz. This trend nicely underscores that 1,2-diazine motifs are more effective H-bond acceptors than 1,4-diazine, and that modifying such functional motifs within cavities greatly benefits the guest-binding potency of TPE-based cyclo[6]arenes. To elucidate the binding modes of TTz with diverse cationic guests, energy-minimized structures of TTz⊃G2 , TTz⊃G4 , and TTz⊃G5 complexes were optimized by density functional theory (DFT) at the B3LYP/6-31G(d) level in CH 2 Cl 2 (Figure 6). [47 – 4 9] The primary structural difference among these complexes was reflected in the dihedral angles of the cavity sidewalls, which appeared to be adaptively adjustable depending on guest size. Their phthalazine motifs maintained small dihedral angles to the cavity plane, much like free TTz did. In TTz⊃G2 complex, the pyridine fragment was suspended outside cavity at an axial tilt of 32.0°, facilitating optimal C–H···N interactions (distances of 2.1 to 2.4 Å). For TTz⊃G4 and TTz⊃G5 complexes , phenyl rings within cavity exhibited comparable dihedral angles, but were clearly bigger than those in TTz⊃G2. Additionally, the bulkier guest G4 induced larger dihedral angles for phthalazine motifs and positioned its ammonium head farther from the cavity center (Figure 6B), potentially accounting for the unusual upfield shift observed in NMR spectra. The TTz⊃G5 complex exhibited two possible binding modes—pseudorotaxane-type threaded and non-threaded assembly structures, with the former being thermodynamically favored by about 3.9 kcal/mol (Figure S79). [50] Overall, despite its shallow cavity, the simulated structures demonstrated that TTz could utilize its endo -functional sites to encapsulate guests through multiple H-bond interactions within the cavity. 2.3. Molecular recognition in aggregate states Above host–guest chemistry coupled with bright aggregate-state emission showcases prospect of macrocycle TTz as an aqueous sensor for environmental pollutants. Water-soluble and highly toxic nitrophenol compounds accumulate in the environment for long-term due to industrial leakage and pesticide degradation (e.g., parathion), posing irreversible threats to ecological sustainability and human health. [51,52] Fluorescence quenching phenomena were firstly compared by adding 5.0 equivalents of phenol (P) or various nitrophenols (2-NP, 3-NP, 4-NP or TNP) to TTz suspension ( f w = 95%, 10 μ M). Impressively, attributed to its preorganized cavity with buried functionalities that facilitate H-bonds formation with hydroxyl groups, TTz exhibited greater sensitivity toward nitrophenol pollutants, as well as size discrimination (Figure 7A). Specifically, 4-NP induced the highest quenching efficiency (48%), followed by 2-NP (35%), whereas 3-NP caused the least effect (11%). [53] Interestingly, despite TNP having higher electron-deficiency, its oversize resulted in a lower quenching effect (42%) than 4-NP. This sensing trend also trued for TPz and TDz but with weaker sensitivity (Figure S68). Fluorescence titration experiments (Figures 7b and S69–S71) revealed a linear relationship for the emission intensity ratio ( I 0 / I ) of TTz at 456 nm against the concentration (0 to 50 μ M) of nitrophenols (2-NP, 4-NP, or TNP). The quenching constants ( K SV ) derived from Stern-Volmer equation were determined to be 9.60×10 3 M -1 , 1.71×10 4 M -1 , and 1.37×10 4 M -1 , respectively (Figure 7D). [54] Corresponding limits of detection (LODs) were estimated at 1.96 µ M, 1.09 µ M, and 1.17 µ M, respectively. Moreover, the fluorescence lifetimes remained comparable to that of free TTz ( τ = 3.03 ns) despite variations in quencher concentrations (Figure 7C). This inferred a static quenching behavior in which TTz forms non-emissive supramolecular complexes with these quenchers, while the observed fluorescence originates from free TTz. [54] No noticeable spectral overlap between the absorption of these nitrophenols and the emission of TTz further ruled out the possibility of resonance energy transfer (RET) process (Figure S72). Subsequently, DFT calculations deciphered the feasibility of electron transfer between the lowest unoccupied molecular orbitals (LUMO) of macrocycle TTz and nitrophenol quenchers, thus confirming the photo-induced electron transfer (PET) mechanism as major contributor to this quenching behavior (Figures 7E and S76). [55] 3. Conclusion In summary, we developed three structurally similar TPE-based cyclo[6]arenes TPz, TDz, and TTz, which differ by modifying pyrazine, pyridazine, or phthalazine motifs. Single-crystal X-ray structures supported that the N atoms in these motifs are oriented toward the cavity interior, serving as endo -functionalized H-bond acceptor sites. In dilute solutions, variations in internal microenvironments resulted in disparate host–guest recognition capabilities, as evidenced by binding experiments with six cationic guests. In contrast to the poor affinity of TPz, both TDz and TTz displayed rich host–guest binding properties with size-selectivity. This is due to their well-defined cavities inheriting the dual H-bond acceptor functionality from the 1,2-diazine motifs (pyridazine and phthalazine), with TTz exhibiting the highest recognition affinity. In aggregate states, they also functioned as sensitive optical sensors for acidic nitrophenol pollutants, with detection sensitivity rising in the order TPz < TDz < TTz. Fluorescence lifetime measurements and DFT calculations elucidated a static quenching mechanism dominated by photo-induced electron transfer (PET). These findings underscore the potential of 1,2-diazine motifs as versatile H-bond acceptors, offering promising avenues for customizing biomimetic host models with emergent functionalities . [Crystallographic Data Centre (CCDC): 2447833 (for TPz ), 2447834 (for TDz ), 2447835 (for TTz ) contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.] Acknowledgements We thank the National Natural Science Foundation of China (22401064, 22161017), the Innovational Fund for Scientific and Technological Personnel of Hainan Province (KJRC2023D34), the Hainan Provincial Natural Science Foundation of China (224QN184), and the Research Start-up Fund of Hainan University (KYQD(ZR)23037) for financial support. Conflict of Interests Statement The authors declare no conflict of interests. Data Availability Statement The data that support the findings of this study are available from the corresponding author upon reasonable request. Received: ((will be filled in by the editorial staff)) Revised: ((will be filled in by the editorial staff)) Published online: ((will be filled in by the editorial staff)) References 1. K. Ariga, H. Ito, J. P. Hill, H. Tsukube, Chem. Soc. Rev. 2012 , 41, 5800. 2. L. Escobar, P. Ballester, Chem. Rev. 2021 , 121 , 2445. 3. J. Zhou, G. Yu, F. Huang, Chem. Soc. Rev. 2017 , 46 , 7021. 4. J. Li, J. Wang, H. Li, N. Song, D. Wang, B. Z. Tang, Chem. Soc. Rev . 2020 , 49 , 1144. 5. X.-Y. Lou, Y.-W. Yang, Aggregate 2020, 1 , 19. 6. Z. Liu, X. Dai, Y. Sun, Y. Liu, Aggregate 2020 , 1 , 31. 7. H.-T. Feng, Y.-X. Yuan, J.-B. Xiong, Y.-S. Zheng, B. Z. Tang, Chem. Soc. Rev. 2018 , 47 , 7452. 8. Y. Sun, P. J. Stang, Aggregate 2021 , 2 , e94. 9. L. Bian, Y. Liang, Z. Liu, ACS Appl. Nano Mater. 2022 , 5 , 13940. 10. J. Zhang, W. Kang, X.-D. Xu, Org. Chem. 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All alkoxy groups are omitted for clarity. Figure 4. Fluorescence emission spectra of TPz, TDz, and TTz in (A) THF solution and (B) solid powder. (C, D) AIE properties of TTz in THF-H 2 O mixtures with different H 2 O fractions ( λ ex = 325 nm, c = 10 µ M). Inset of (D): particle size distributions of TTz ( f w = 95%) studied by DLS and photograph under 365 nm UV light. Figure 5. List of cationic guests selected for this work, with PF 6 – as the counter anion. (A) Partial 1 H NMR spectra (CDCl 3 , 1.0 mM) of free TTz, and it with 3.0 equiv. G4 or 1.0 equiv. G5. (B) Association constants ( K a , M -1 ) for these macrocycles with guests G1 to G6 in CDCl 3 . a The K a is too small to measure. Figure 6. Top view of the energy-minimized structures of (A) TTz⊃G2, TTz⊃G4, and TTz⊃G5 complexes. (B) Front view of TTz⊃G4 and TTz⊃G5 complexes. The purple dotted lines indicate C–H···N interactions, and all alkoxy groups are omitted for clarity. Figure 7. (A) Fluorescence quenching efficiencies of 5.0 equivalents different analytes for TPz, TDz, and TTz. (B) Emission intensity change of TTz suspension in THF-H 2 O (f w = 95%, 10 µM) upon gradual addition of 4-NP and (C) corresponding lifetime decay profile. (D) Stern-Volmer plots of emission intensity ratio (I 0 /I) of TTz versus 2-NP, 4-NP, or TNP concentration. (E) The HOMO and LUMO energy level diagrams for TTz, 2-NP, 4-NP, and TNP. Table of Contents: Diazine Endo -Functionalized Tetraphenylethylene-Based Cyclo[6]arenes for Molecular Recognition in Both Solution and Aggregate States N. Pan, S. Liu, W. Tan, L. Yao, J. Xie,* K. Zhu, C. Jia* Keywords : cyclo[6]arenes, diazine, endo -functionalized cavity, hydrogen bonds, m olecular recognition To overcome poor molecular recognition in dilute solutions of tetraphenylethylene embedded cyclo[6]arenes, three macrocycles with functionalized cavities featuring diazine groups as endo -binding sites are synthesized. Their recognition affinity continuously improves with increasing hydrogen bond acceptance of diazine groups. The phthalazine modified macrocycle achieves optimal dual-state recognition for size-selective cation binding in dilute solutions and nitrophenol detection in aggregates. Information & Authors Information Version history V1 Version 1 22 July 2025 Peer review timeline Published Aggregate Version of Record 29 Sep 2025 Published Copyright This work is licensed under a Non Exclusive No Reuse License. Collection Aggregate Keywords endo-functionalized cavity cyclo[6]arenes diazine hydrogen bonds molecular recognition Authors Affiliations Nan Pan Hainan University View all articles by this author Shuhong Liu Hainan University View all articles by this author Weichen Tan Hainan University View all articles by this author Linbin Yao Hainan University View all articles by this author Jialin Xie 0009-0000-1656-7720 [email protected] Hainan University View all articles by this author Kelong Zhu Sun Yat-sen University School of Chemistry View all articles by this author Chunman Jia Hainan University View all articles by this author Metrics & Citations Metrics Article Usage 322 views 190 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Nan Pan, Shuhong Liu, Weichen Tan, et al. Diazine Endo-Functionalized Tetraphenylethylene-Based Cyclo[6]arenes for Molecular Recognition in Both Solution and Aggregate States. Authorea . 22 July 2025. 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