Aggregation Induced Emission Enhancement of a fascinating Pyrene mediated fluorescent chromophore

Aggregation Induced Emission Enhancement of a fascinating Pyrene mediated fluorescent chromophore | 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 Research Article Aggregation Induced Emission Enhancement of a fascinating Pyrene mediated fluorescent chromophore Uttam Panda, Rajat Kumar Sahoo This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6450767/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Pyrene mediated fluorescent chromophore manifests aggregation induced emission enhancement property followed by discotic nano-aggregates formation in THF- water medium (1:4). The property is theoretically interpreted from DFT and TDDFT calculation. Pyrenenyl Schiff base J-aggregates Emission DFT calculation Figures Figure 1 Figure 2 Figure 3 1. Introduction Conjugated luminescent materials with high emission efficiency attracted scientists’attention due to their novel role in real world as bio-and chemosensors, stimuli-responsive nanomaterials, molecular conducting wires, organic light-emitting diodes ( OLED ) , photovoltaic cells. The pioneer working of Tang’s et al in the field of AIE and AIEE materials such as siloles ,[ 1 ] 1-cyano-trans-1,2-bis-(40-methylbiphenyl)ethylene ( CN-MBE ), [ 2 ] 2,5-diphenyl-1,4-distyrylbenzene ( DPDSB ) derivatives, [ 3 ] diphenyldibenzofulvene ( DPDBF ) derivatives, [ 4 ] conjugated polymers, [ 5 ] and others [ 6 ] , focused a new light for designing new chromophores with less synthetic difficulties. Naturally, molecular aggregation of fluorophores effective for following consideration with respect to the alignment of luminophoremoiety [ 7 , 8 ] in the aggregated states: viz, conformational planarization, prevention of close intermolecular interaction rendering emission quenching, and restriction of intramolecular rotation (RIR). The effects of intermolecular interactions on emission changes are correlated with the aggregation morphology, such as H-type (nonemission) or J-type (emission) aggregation. The strategy to overcome emission quenching by intermolecular π--π stacking, a notorious problem and retaining highly fluorescent properties of organo luminophores in the condensed phase can be performed, introducing a bulky substituent by preventing unfavorable aggregation and diminishing intermolecular interaction[9].On contrary, incorporation of efficient fluorophoric probe whose aggregates emit excellent compared to their solution phase terminate the above problem. Based on the intra- and intermolecular effects and the molecular skeleton of the chromophore, we have formulated two concepts for the design pyrene appended AIEE: (1) further extension of the p-conjugation of the luminophore moiety, introducing a imine linkage with that of chromophore, and (2) sandwiching of the luminophore moiety between flexible carbon chain flanked with benzene moiety. To the best of our knowledge, Pyrene appended fluorophores are less reported and possess lot of restrictions in real application. Pyrene appended organic dyes possess p-type semiconducting properties and organic semiconducting material based sensor devices permit that the materials should have the solubility in organic solvent. Aggregation induced emission measurement in dilute THF solution on increasing the concentration of water the emission intensity has amazingly improved with red shift of emission maxima (from 413 nm to 475 nm) due to π-π stacking interaction of pyrene moiety. SEM image shown in Fig. 2 b.confirm the dramatic event of change of emission occurring by J-type agglomerate formation in the system. After an optimum level concentration of water (95%) its emission intensity drastically decreased due to probable complete molecular agglomeration. The calculated quantum yield enhancement of the sample (Φ, 0.025 to 0.44) with variation of water quantity reveals that the restricted intra-molecular rotation (RIR) process based AIE [ 10 ] is operating in system containing two pyrene moieties flanked with flexible 4,4’ di amino di phenyl methane unit. 2. Experimental Section 2.1. Materials and Methods. All chemicals were of reagent grade and were purchased from Merck, India. solvents used here were of spectroscopic grade and used as received. Milli-Q Milipore 18.2MΩcm -1 water was used in aggregation induced emission study. 1-pyrene carbaldehyde and 4,4’-methylene bis aniline were purchased from Sigma Aldrich(India). Microanalytical data (C, H, and N) were collected on Perkin–Elmer 2400 CHNS/O elemental analyzer. Spectroscopic data were obtained using the following instruments: UV–Vis spectra by Perkin–Elmer UV–Vis spectrophotometer model Lambda 25; FTIR spectra (KBr disk, 4000–400 cm -1 ) by Perkin–Elmer FT-IR spectrophotometer model RX-1; the 1 H NMR spectra by Bruker (AC) 300 MHz FTNMR spectrometer. Emission was examined by LS 55 Perkin–Elmer spectrofluorimeter at room temperature (298 K) in CH 3 CN, THF solutions under degassed condition. The fluorescence quantum yield of the complexes was determined using anthracene as a reference with known Φ R of 0.27 in ethanol. The complex and the reference dye were excited at same wavelength, maintaining nearly equal absorbance (~ 0.1), and the emission spectra were recorded. The area of the emission spectrum was integrated using the software available in the instrument and the quantum yield is calculated according to the following equation: Here, Φ S and Φ R are the fluorescence quantum yield of the sample and reference, respectively. A S and A R are the area under the fluorescence spectra of the sample and the reference, respectively, (Abs) S and (Abs) R are the respective optical densities of the sample and the reference solution at the wavelength of excitation, and η S and η R are the values of refractive index for the respective solvent used for the sample and reference. 2.2. Preparation of (NE, NE)-4,4’-methylenebis(N-(pyren-1-ylmethylene)aniline) (HL) The yellow colored fluorescent ligand was prepared by adopting same procedure of Schiff base preparation via one pot synthetic strategy by mixing two equivalent of 1-pyrene carbaldehyde and one equivalent of 4,4’diamino diphenyl methane in dry methanol with respective yield 95% yield, M.P. 175 ± 5 ◦ C has been shown in Scheme 1. The TOF MS ES + spectral study of HL contains one molecular ion intense peak (L + H ) + . 2.3. Theoretical Interpretation To understand the electronic structures of HL , we carried out density functional theory (DFT) and time dependent density functional theory (TDDFT) calculations with the B3LYP/6–31 + G(d,p) method basis set using the Gaussian 03 program. The optimized geometry and the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of HL is presented in Fig. UV-vis spectra of L was calculated using the TDDFT method in THF. Calculated absorption peaks had agreed well with the experimentally observed peaks (Tables). In case of L, the transition from HOMO to LUMO, HOMO-1 to LUMO, HOMO-1 to LUMO + 1 and HOMO-3 to LUMO had contributed mainly to the excitation at 397, 388, 377 and 346 nm respectively ( Supplementary Tables 1 to 3 ). LUMO + 1, HOMO-3 to LUMO and HOMO-5 to LUMO respectively ( Supplementary Tables 1 to 3 ) . The transitions below 300 nm correspond to admixture of imine to pyrene charge transfer and inter-pyrenyl charge transfer whereas transitions above 300 nm correspond to inter pyrene charge transfer. Due to adjacent conjugated pyrene group it is tough to transfer charge from imine to farther pyrene group overcoming the high energetic barrier of middle aliphatic methylene group. So imine to pyrene charge transfer is high energetic process. Moreover presence of two pyrene groups on different planes minimizes the charge delocalization which further makes it a high energetic process. DFT studies support the fact and in this case pyrene to imine charge transfer is an energetically favorable transition. 3. Results and discussions 3.1. Photophysical properties of (NE,NE)-4,4’-methylenebis(N-(pyren-1- ylmethylene)aniline) In FTIR spectrum H L shows n(C=N) band at 1584 cm -1 ( Supplementary Fig S 1 ). The 1 H NMR spectral data of HL shows signals for imine –CH proton at 11.53 ppm. The pyrene protons show signal at 7.2-8.06 ppm. Meanwhile aliphatic methylene protons show signal at 3.5 ppm. ( Supplementary Fig S 2 ). Elemental analysis: calculated % (C, 90.67; H, 4.50; N, 4.823); found (C, 91; H, 4.11;N,4.89) TOF MS ES + : Calculated for C 47 H 30 N 2 (L+H) + (m/z): 623; found: 623 ( Supplementary Fig S 3 ) .This has been justified from TDDFT Study ( Fig 3.). 3.2. Aggregation induced emission enhancement (AIEE ) THF solution of HL responds intense absorption band at 250-280 nm in association with transitions at 320–415 nm ( Supplementary Fig S 4 ) The absorption peak nearly at 400 nm may be originated from π-π* transition due to thorough conjugation of multiple aromatic rings of imine functionalized pyrene unit. Gradually addition of water (10% to 80%) to its THF solution results amazing enhancement of optical density at 250-280 nm while drastically diminishes the value at 400 nm presumably to initiate agglomeration ( Supplementary Fig S 4 ). In fluorescence spectroscopic measurement, THF solution of HL exhibits red shift of emission maxima (475nm) with many fold enhancement of intensity( Fig 1. ) after addition of water (upto 95%) attribute to aggregation induced emission enhancement (AIEE ) operating through restricted intra molecular rotation (RIR) of bulky and stereo-chemical rigid imine mediated pyrene motif. The quantum yield increment of the sample (Φ, 0.025 to 0.44) as a linear function of water concentration (percentage) and isolation of aggregated nano material through SEM imaging confirms the above RIR mechanism of emission enhancement phenomenon( Fig 2a & 2b. ) . 4. Conclusion Pyrene appended luminophores are excellent emissive in nature. Here, we have synthesized and characterized pyrene appended Schiff base, (NE,NE)-4,4’-methylenebis(N-(pyren-1-ylmethylene)aniline) ( HL ). It shows aggregated induced emission enhancement through restricted intra-molecular rotation upon addition of water to THF mixture (4:1, v/v) with significant quantum yield (Φ) enhancement. Complete Aggregation has been confirmed by SEM analysis. DFT, TD-DFT calculation has been employed to explain the spectral properties. Declarations Author Contribution Dr. Uttam Panda prepared the manuscript and performed all experiments, data collection and interpretation. Mr. Rajat Kumar Sahoo assisted with me regarding SEM imaging and analysis. Acknowledgments Financial support from Council of Scientific and Industrial Research for fellowship of Dr. Uttam Panda (grant No. 01(2731)/13/EMR-II) and Infra structure support from Jadavpur University and BCET is thankfully acknowledged. The authors have no conflict of interest Data Availability “Data is provided within the manuscript and supplementary information files” Supporting Materials All spectroscopic figures and DFT, TD-DFT details along with experimental writeup data analyses are given in Supplementary Materials Section ( Figs S1- S4 and Tables 1 to 3 ) . References Forster T, Kasper KZ (1955) Elektrochem 59:976 Baxter JB (2012) Commercialization of dye sensitized solar cells: Present status and future research needs to improve efficiency, stability, and manufacturing. J Vac Sci Technol A 30(2):020801–020819 Hardin BE, Snaith HJ, McGehee MD (2012) The renaissance of dye-sensitized solar cells. Nat Photonics 6(3):162–169 Snaith HJ (2010) Estimating the Maximum Attainable Efficiency in Dye- Sensitized Solar Cells. Adv Funct Mater 20(1):13–19 (a) Deans R, Kim J, Machacek MR, Swager TM, J. Am. Chem. Soc., 122, 8565; (b) Holzer W, Penzkofer A, Stockmann R, Meysel H, Liebegott H, Horhold HH, Polymer, 2001, 42, 3183., Han L, Koide N, Chiba Y, Islam A, Mitate T (2000) Modeling of an equivalent circuit for dye-sensitized solar cells: improvement of efficiency of dye-sensitized solar cells by reducing internal resistance. C. R. Chim. 2006, 9 (5 – 6), 645 – 651 (a) Kim S, Zheng Q, He GS, Bharali DJ, Pudavar HE, Baev A, Prasad PN, Adv. Funct. Mater., 16, 2317; (b) Kim S, Ohulchanskyy TY, Pudavar HE, Pandey RK and Prasad PN, J. Am. Chem. Soc., 2007, 129, 2669; (c) Xu J, Liu X, Lv J, Zhu M, Huang C, Zhou W, Yin X, Liu H, Li Y, Ye J, Lam L, Mahtab F, Jim CKW, Tang L, Sun J, Sung HHY, Williams ID, Tang BZ, Appl. Phys. Lett., 2009, 94, 253308; (e), Yuan CX, Tao XT, Ren Y, Li Y, Yang JX, Yu WT, Wang L, Jiang MH, J. Phys. Chem. C, 2007, 111, 12811, Liu H, Avrutin V, Izyumskaya N, Özgür Ü, Morkoç H (2006) Transparent conducting oxides for electrode applications in light emitting and absorbing devices. Superlattices Microstruct. 2010, 48 (5), 458 – 484 Hong YN, Lam JWY, Tang BZ (2009) Chem. Commun., 4332, Grätzel, M. Photoelectrochemical cells. Nature 2001, 414 (6861), 338 – 344 (a) He JT, Xu B, Chen FP, Xia HJ, Li KP, Ye L, Tian WJ, J. Phys. Chem. C, 113, 9892; (b) Kim S, Zheng Q, He GS, Bharali DJ, Pudavar HE, Baev A and Prasad PN, Adv. Funct. Mater., 2006, 16, 2317, Barbé, Arendse CJ, Comte F, Jirousek P, Lenzmann M, Shklover F, Grätzel V (2009) M. Nanocrystalline Titanium Oxide Electrodes for Photovoltaic Applications. J. Am. Ceram. Soc. 1997, 80 (12), 3157 – 3171 Sato T, Jiang D-L, Aida T, Am J, Chem S, 121,10658;, Langhals H, Krotz O, Polvorn K, Mayer P, Wakamiya AC, Mori K, Yamaguchi S (1999) Angew. Chem., Int. Ed., 2007, 46, 4273, Theoretical and Experimental Study of a Dye-Sensitized Solar Cell Mona Bavarian, Siamak Nejati, Kenneth K. S. Lau, Daeyeon Lee, and Masoud Soroush Industrial & Engineering Chemistry Research, dx. doi.org/10.1021/ie4016914 | Ind. Eng. Chem. Res (a) Cai M, Gao Z, Zhou X, Wang X, Chen S, Zhao Y, Qian Y, Shi N, Mi B, Xie L, Huang W, Phys. Chem. Chem. Phys., 14, 5289; (b) Hong Y, Meng L, Chen S, Leung CWT, Da LT, Faisal M, Silva DA, Liu J, Wing J, Lam Y, Huang X and Tang BZ, J.Am.Chem.Soc., 2012, 134, 1680; (c) Qina A, J. W. Y. Lamb and B. Z., Tang (2012) Prog. Polym. Sci., 2012, 37, 182 Schemes Schemes 1 and 2 are available in the Supplementary Files section Additional Declarations No competing interests reported. Supplementary Files SupplementaryMaterial.docx Schemes.docx Cite Share Download PDF Status: Posted 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-6450767","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":453201009,"identity":"0c714f22-1de2-4876-9c4e-3d64853e4a27","order_by":0,"name":"Uttam Panda","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA10lEQVRIiWNgGAWjYNACHgY5fvYGIMPAggjVbMxgLcaSPQdAWiSI1cLAkLjhRgKIJkKLwf3+g59uyBw2lpz5/OqGHwUSDPzt3Qn4tRxjZpbO4Tksxy+dU3azB+gwiTNnNxDSwgDSYiw5OyftBg9Qi4FELkEtzL+BWhI33DyTdvMPkVrYpMFabrAfu02ULZLHks2sc3jSgYGcw3ZbxkCCh6Bf+A4ffHw7t8caGJXHn91888dGjr+9F78WMGDsAZE8BmCSsHIw+AEi2B8QqXoUjIJRMApGGgAAnHlGAzglqnkAAAAASUVORK5CYII=","orcid":"","institution":"Balasore College of Engineering and Technology","correspondingAuthor":true,"prefix":"","firstName":"Uttam","middleName":"","lastName":"Panda","suffix":""},{"id":453201010,"identity":"13378052-4f5e-45d5-975f-078b9f7c0ffc","order_by":1,"name":"Rajat Kumar Sahoo","email":"","orcid":"","institution":"Balasore College of Engineering and Technology","correspondingAuthor":false,"prefix":"","firstName":"Rajat","middleName":"Kumar","lastName":"Sahoo","suffix":""}],"badges":[],"createdAt":"2025-04-15 04:38:14","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6450767/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6450767/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":82239684,"identity":"d9c7e045-534d-42cb-9e9f-fda025fd5193","added_by":"auto","created_at":"2025-05-08 07:48:25","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":94240,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eAIEE study of (NE, NE)-4, 4’-methylene bis (N-(pyren-1-ylmethylene) aniline) (HL) in THF\u003c/em\u003e upon \u0026nbsp;\u003cem\u003egradual addition of water.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6450767/v1/8734fd78fc2524c53dfc9220.png"},{"id":82239690,"identity":"33bd2f9d-a59d-4be8-a4f8-b7db67e3df8b","added_by":"auto","created_at":"2025-05-08 07:48:26","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":156751,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003e\u003cstrong\u003ea. Variation of quantum Yield as function of water. b. SEM image of J-aggregates of HL in THF-water (1:4)\u003c/strong\u003e\u003c/em\u003e\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6450767/v1/e78f262851733e6ed69981c9.png"},{"id":82239687,"identity":"f0b34e41-b938-4463-b2a4-5b7c1499c8f9","added_by":"auto","created_at":"2025-05-08 07:48:26","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":223084,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eDFT computed HOMO and LUMO\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6450767/v1/af311788b8497b5d854113aa.png"},{"id":82801528,"identity":"ad365e81-6884-4c1a-916c-9fa457e72556","added_by":"auto","created_at":"2025-05-15 11:23:24","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1107285,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6450767/v1/3bf8dd98-c155-433a-9e6f-982c312ea0ba.pdf"},{"id":82239692,"identity":"6ca3448c-769c-4f24-8fba-eb5b7ecd2d4b","added_by":"auto","created_at":"2025-05-08 07:48:26","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":813340,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryMaterial.docx","url":"https://assets-eu.researchsquare.com/files/rs-6450767/v1/3a7c6bf6b8b9727bbed91314.docx"},{"id":82240645,"identity":"6a48ab09-2cc3-46af-aaf1-d293fe1de1c3","added_by":"auto","created_at":"2025-05-08 07:56:26","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":235483,"visible":true,"origin":"","legend":"","description":"","filename":"Schemes.docx","url":"https://assets-eu.researchsquare.com/files/rs-6450767/v1/6f033d96289346bd5a4fd8e9.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Aggregation Induced Emission Enhancement of a fascinating Pyrene mediated fluorescent chromophore","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eConjugated luminescent materials with high emission efficiency attracted scientists\u0026rsquo;attention due to their novel role in real world as bio-and chemosensors, stimuli-responsive nanomaterials, molecular conducting wires, organic light-emitting diodes (\u003cb\u003eOLED\u003c/b\u003e\u003cem\u003e)\u003c/em\u003e, photovoltaic cells. The pioneer working of Tang\u0026rsquo;s et al in the field of AIE and AIEE materials such as siloles\u003csup\u003e,[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]\u003c/sup\u003e 1-cyano-trans-1,2-bis-(40-methylbiphenyl)ethylene (\u003cb\u003eCN-MBE\u003c/b\u003e), \u003csup\u003e[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/sup\u003e 2,5-diphenyl-1,4-distyrylbenzene (\u003cb\u003eDPDSB\u003c/b\u003e) derivatives,\u003csup\u003e[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/sup\u003e diphenyldibenzofulvene (\u003cb\u003eDPDBF\u003c/b\u003e) derivatives,\u003csup\u003e[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/sup\u003econjugated polymers,\u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e and others\u003csup\u003e[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e, focused a new light for designing new chromophores with less synthetic difficulties. Naturally, molecular aggregation of fluorophores effective for following consideration with respect to the alignment of luminophoremoiety\u003csup\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/sup\u003e in the aggregated states: viz, conformational planarization, prevention of close intermolecular interaction rendering emission quenching, and restriction of intramolecular rotation (RIR). The effects of intermolecular interactions on emission changes are correlated with the aggregation morphology, such as H-type (nonemission) or J-type (emission) aggregation. The strategy to overcome emission quenching by intermolecular π--π stacking, a notorious problem and retaining highly fluorescent properties of organo luminophores in the condensed phase can be performed, introducing a bulky substituent by preventing unfavorable aggregation and diminishing intermolecular interaction[9].On contrary, incorporation of efficient fluorophoric probe whose aggregates emit excellent compared to their solution phase terminate the above problem. Based on the intra- and intermolecular effects and the molecular skeleton of the chromophore, we have formulated two concepts for the design pyrene appended AIEE: (1) further extension of the p-conjugation of the luminophore moiety, introducing a imine linkage with that of chromophore, and (2) sandwiching of the luminophore moiety between flexible carbon chain flanked with benzene moiety. To the best of our knowledge, Pyrene appended fluorophores are less reported and possess lot of restrictions in real application.\u003c/p\u003e \u003cp\u003ePyrene appended organic dyes possess p-type semiconducting properties and organic semiconducting material based sensor devices permit that the materials should have the solubility in organic solvent. Aggregation induced emission measurement in dilute THF solution on increasing the concentration of water the emission intensity has amazingly improved with red shift of emission maxima (from 413 nm to 475 nm) due to π-π stacking interaction of pyrene moiety. SEM image shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb.confirm the dramatic event of change of emission occurring by J-type agglomerate formation in the system. After an optimum level concentration of water (95%) its emission intensity drastically decreased due to probable complete molecular agglomeration. The calculated quantum yield enhancement of the sample (Φ, 0.025 to 0.44) with variation of water quantity reveals that the restricted intra-molecular rotation (RIR) process based AIE\u003csup\u003e[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/sup\u003e is operating in system containing two pyrene moieties flanked with flexible 4,4\u0026rsquo; di amino di phenyl methane unit.\u003c/p\u003e"},{"header":"2. Experimental Section","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n \u003ch2\u003e2.1. Materials and Methods.\u003c/h2\u003e\n \u003cp\u003eAll chemicals were of reagent grade and were purchased from Merck, India. solvents used here were of spectroscopic grade and used as received. Milli-Q Milipore 18.2MΩcm\u003csup\u003e-1\u003c/sup\u003e water was used in aggregation induced emission study. 1-pyrene carbaldehyde and 4,4\u0026rsquo;-methylene bis aniline were purchased from Sigma Aldrich(India).\u003c/p\u003e\n \u003cp\u003eMicroanalytical data (C, H, and N) were collected on Perkin\u0026ndash;Elmer 2400 CHNS/O elemental analyzer. Spectroscopic data were obtained using the following instruments: UV\u0026ndash;Vis spectra by Perkin\u0026ndash;Elmer UV\u0026ndash;Vis spectrophotometer model Lambda 25; FTIR spectra (KBr disk, 4000\u0026ndash;400 cm\u003csup\u003e-1\u003c/sup\u003e) by Perkin\u0026ndash;Elmer FT-IR spectrophotometer model RX-1; the \u003csup\u003e1\u003c/sup\u003eH NMR spectra by Bruker (AC) 300 MHz FTNMR spectrometer. Emission was examined by LS 55 Perkin\u0026ndash;Elmer spectrofluorimeter at room temperature (298 K) in CH\u003csub\u003e3\u003c/sub\u003eCN, THF solutions under degassed condition. The fluorescence quantum yield of the complexes was determined using anthracene as a reference with known \u0026Phi;\u003csub\u003eR\u003c/sub\u003e of 0.27 in ethanol. The complex and the reference dye were excited at same wavelength, maintaining nearly equal absorbance (~\u0026thinsp;0.1), and the emission spectra were recorded. The area of the emission spectrum was integrated using the software available in the instrument and the quantum yield is calculated according to the following equation:\u003c/p\u003e\n \u003cp\u003e\u003cimg src=\"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAATAAAAA1CAYAAADGQbf0AAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsMAAA7DAcdvqGQAAA3tSURBVHhe7Z1J6BRHF8DLD08aI2LARAm4oBIxwQVFxX0Bt6PRKEQPLiHqwRX0IK6gB7eDeHDDJcTtElwPMSoqCIpJEERE1IM7KCIqeBDmm1+lS/vf9kxXdVdv868fNDPT0z3d9erVq1eval63qFQRDofDUUL+5706HA5H6XAGzOEoIU+fPhXdunUTLVq0+Gw7deqUd1T5mDVrVmiZ2B+GM2AOR0kZM2aMePPmjSAK5N8mT57sHVE+Dhw48Fl5/v77b/HVV195RzTFGTCHw5E6eFFp0NAGrKxutqkbXQ8TGbx9+1bs3bvX+5Q+XItrNhds1mua+HVmy5Yt3t748Dt4UmnQ8B5YGd1sUzc6Ch0ZYEi2bdsmpk2b5u1JH67FNZuLEbNdr2lx+fJlceXKFfHkyRNx9OhR8c8//3jfFI9CGTAsdXOgiOU8cuSINGhffPGFtyd9uFbfvn3ltdOkueiVLaZOnSq++eYbuQ0bNszbG480vS8ojAFLu6BFoYjlZMhw584d0b17d2+POXhRY8eOleVj+MFv6jBy5Ehx7do17eNNaS56lQbUyZdffik7mThkIfvYBgy3kiFAo7v/xInKPC2tw40bN8TXX39t5H0F5cK5586dE5s3bxZDhw6VvbcOnNezZ095D45iwVBy3rx53qdiEtuAnT9/XgwcONDKkKOovSRGeunSpaJTp07enmQUtZzHjx+XRkSXWnKhx965c6f44YcfvD16cG3uwTbO+4oPwfuHDx/K98eOHZOvJmQl+1gGDK8Lt3/06NHenvgUVcko4/Lly8XLly+9PckoajkxOrdv39Y20vXk8uzZM9GyZUtjveDa3IPNYaQzXvFhVnTZsmVy69ixo2jVqpX3jR5Zyj6WAbt79658TRIzKTqrV6+Ws0Nt27aVw6tGBaMDumWsJxe88m+//dZYL9TvqHtx5EtwtrTIM/ZGBuzMmTPil19+ET/99JN49OiR+PHHHz8aszgUtZdUsZ0BAwaILl26iDZt2sjPcSmyN/D48WNtLzNKLjdv3pTeFLOKGDnKHVxHxNCT/WpT33MP3IsNiizvrNizZ4+sAzWhQtsl5INsmGyx6e36yVr22gYMRfvrr7/E2rVrRZ8+fcSOHTukIDZs2OAdYUZRlYz4zqFDh2Q5aZBJaZTGFCUXGgRrh96/fy9GjBghXrx4IQP6GzdulOcCrxhB1j6xLo31aSaxNx2c8RLi0qVLon///mLlypXi9evX0pgBYZ/du3eLf//9NxVvNw/ZaxkwlI7gLGNiZbnVMIFes1FmIinHpk2bxIoVK+RnyoZHYWOioszoyEXFvzhG6YaKhYV5VpyLJ68be3PoM3z4cLn0gY4GZ2Px4sVi4sSJ8jsMWiOFRSINGMq7fft2MX/+fDk17p99VEMG0wZe1F5ywYIFcsalX79+cniEx5mERvEGdORSK/7Vvn37j0aKRsW0/Lhx46Q3NmfOnNhrjMJw3tcnlEe8aNGiJu2TNmuyzEWXvGQfacCIcTGdSm+KMVOzj0pAxMFMKKqS4WUSM+De2PgbRdeuXY2XBCgapTHpyoWGMWHChCaNJcyoEQNjaDNlypTU4jCO/9b2AUNJRdw2W2QiDRju/4cPH6TL6Z99/P3332Ugl5XUZccf31EwJMLdVjEajqEhE/djgZ+K65QdvCOGfmExER25gGoY/n2cS/xLeQD8hjJYM2bMkK/+xat+Ty0OzvtqCuvqgp5W0KjZ0uk8ZR9pwPwKroaPGDJWXaPcJsPHIioZM2bMrDJM9peFymZmTDXs3377Tfz555/ijz/+ECdOnKgbQyhTY6IcxESC6MoFeI8BUg1DzVbjaTEFj+dOA6HTA2UEFeq3lEyZMEKGbDSwqIZVJnnb4tWrV+Lq1avi3bt33p5PIK/Tp0838bRUKMhv1Ex0uhZZyJ5JH/7qFkr14pHs3r27MmTIkEqPHj0q06ZNq2zdurXy5s0b+R2vY8aMoQSVmTNnyn1haF7KKtXhTmXu3Lkf79VPVSiVaqOT98VGGTiOc6pDpI/71Xfr1q2rbN682Tu7NhyfBtzvkiVLvE/61JOBgno7efKkfG8qF75jQyfUeQMGDKhUG5D8PQiey3HolIJr+3WH35s6daq8F46rp1fAb5aVNOoVPUXeHKNQ9arqGThOR6frkYXsueda96k1C0mwld500KBBsmdmVkP1ylUBykAsryyAKwvcM1P9VRnIDY+SMtE73bt37+N+9d2qVavkecRwGg16atXDmcqF79jQCXUecVI16wXBczkOnVJwbb+3gC716tVLhirw3OrFIZuj9xUFOoq8/cNHRk942v6YmNLluDpdBNlrGTBgTB0W/ENIxDSqFt7b8zl5FbSemx0HKpq/VqgFnUHSLCfyDbrR3E/Y8Ir7U2t/dGSAUvPbDDOyhmsyhPQ3LIapa9asEZ07d5bLABiOhtEIxitYrzp1agoyPnv2bOjsY5RO16IostcyYARfq+5oEyUDBLN+/XrZU164cCF0VslmQWtltPRv/pXf7dq1E4MHDxatW7f29sQDxck7DtOhQwcxatQo79N/EBgnruT/NwT3iQFgjRXoyAClJrZ58eJFb092cO8E//0Ni87y8OHDcqErk0TK268FephlJlmwlU02WK86dWoKv8XiVb8DoqPTZUDLgCE8rHTQeuPq79+/X64NYrYy6V9uogjLaBnc4rrDtUBJMU644LzSWxZl5pWGvWTJEjm8pfNAIVlwigyiGn0QhnTPnz+30ih14Vr0/P6GqTpLVvNjVJF7GKrD4DeyziQLaWWTtVmnCrWQWM3yJtVpJftCUL2R1Ej55yOpF+i0SRblrBfIpJzjx4+Xge9gWU1kwDFHjx71PqVP1Qtocl8q0Iw8Kav6rCYLFH55E+TnuDygTvyTEXGoVa/16hSy0u0gebTpxEH8OKRhpU2HkFnANW2XMy5hyyFMoIcnnXBWzJ49u4lX4Z9AwONQn9VkQRA8FLyH4Op/U/BIiphNFpLWaRFBXrYeGpKaAYsC19g0o6vpENJ2EN8GDJlMA6bA8I44YxCUgRnAffv2iV9//VUaBb9MiyiDJPg7DEIbrF0yHVoF64DzMZLVXj7zbLJh9RpVp3lhq7NmZpmFz1UvMvFDQ1IxYDoFVYtiTZWvSJhWKBWFgU2y4twPSr1161Y5kUKjw2Phz9T0akVQeNsE5W2aSRZq1QFGowjZZItap7aMF9h8aIh1A6ZTUCrCVkbXvDCtUMpsM8MrkFyQJSz+IRQKz2xx2k/6yRsMjkkmWahXByzlKEI22eZUp8gsyUNDIJchpJoiThq7KBNpZHilVw6rfP6+418o2ggEO4zg3490KEM2Wd06zTI0YNP78sNQUuehIbXCJ2DVgEUV1HZG17wwrVAVb7GV4bW5ESZvlgaYeLNRdaBSQ+HlYOS4ZjDAzNCT/WpT33MfYTnPGoEw2dsA2SV5aIjCmgGLKig3bDOja16YVigxl3qZTB3pE1UHDGUIKuedTba5kPShIX4yGUJS8c0ho2sQyuUyvCYjqQegUwcq/uWyyTYlLe/L5kNDrBiwegVFgWxndM0L0wq1neG1uWGjAZUlm2zRSMt42SaxAYsqKDEumxld88K0QvE6iaVwDhtrXsIymTrSQ7cOXDZZc/gvJbLN+qlHQVIfQuKCR2V0JT5GwdkQioo7lBV/zEXBMMWfybTRymwb5FKvw8AzqpVJFnTqAFRH6t/HuVlmky0aUbLP66lHYSQyYFEFBb+iqeEjhoyVzygYCsLMJIvbCJASr2DIWSR0yqnQzWRa9DIXHTrEWn+z0a0D4D0GSGVaSZpNFuNHh5R26nFbmVbikPVTjxj+15owiW3AdBs1BWXx4MKFC8WuXbvE9evXZdoWVi8TEwNmdXQT2GWNbjmV4k6fPl2W8eeff5bKT8+Nmz137lx5HK/KxS5qmfNGR+boznfffdckyG5aB3yH/Dn++++/l9clDxmb+ksauvngwQM5AcX3xMDocFTgmetzH0qXbaRpzhNdfVeea1ZPPapJ9WZjYXoq/yivlRqY7/g9Mg/401Un5datW5XevXtXqr2kt8ecBCKqi2mZydwwadIk75M+NmSQJSbyrpelICu4Pveh4LPJPcWt1zSyUZjKPpi2mvfs88vDBmQbqZV2O5YHpmul/dTK6AqmCex0SepmxymnLqZlrudG1yPPoUbaMOzLK5MscF2GkGr4CcpzU69RxK3XvEF/o556lEWc19iAxWnUuJvMAPkrWqG+i0pglzVpGq+iljlvTGVO40F+eWSSBWK5GJ/gcAnjFSdNc56YyB5DpPPUoyzivKnPQgKWOSyjK4Ig9kBAnyApyyuY/VHxiUakOZZZh7gdRh6ZZIHrYaD82WSZjUvDy0gbU9nT4RKo9zskGPNg2uosYtvGBiyOkhHwDHtiEQF+kwR2WRKnnDoUucxlhbxyzB5mCXms/E/nwqBhCGjcvBYp9bht0Fudpx7huOg8nCUJmXhgecLKa1Zgo1T+rcjufVjmWWIlGLo4lEEGSToMjEiWmWQhmE2W9+yjcVMWZtyDHZLterUB95C0s8Z4hz31KK3Ytp+GNmAIM/gsQ7Ul+f9V2tTKPBvmxUZRVhk0Ijbr1QY2jBeEDR+zivM2vAfmcDjSRa3FU/9GyDLO26JqgdMJ9jgcjtTAw2HIdv/+fW/PJ06ePFla75ph9sGDB71Pn5g5c2aop+oMmMPhKC1uCOlwOEqLM2AOh6O0OAPmcDhKizNgDoejpAjxf2vfpDpQbpHXAAAAAElFTkSuQmCC\" width=\"304\" height=\"53\"\u003e\u003c/p\u003e\n \u003cp\u003eHere, \u0026Phi;\u003csub\u003eS\u003c/sub\u003e and \u0026Phi;\u003csub\u003eR\u003c/sub\u003e are the fluorescence quantum yield of the sample and reference, respectively. A\u003csub\u003eS\u003c/sub\u003e and A\u003csub\u003eR\u003c/sub\u003e are the area under the fluorescence spectra of the sample and the reference, respectively, (Abs)\u003csub\u003eS\u003c/sub\u003e and (Abs)\u003csub\u003eR\u003c/sub\u003e are the respective optical densities of the sample and the reference solution at the wavelength of excitation, and \u003cem\u003e\u0026eta;\u003c/em\u003e\u003csub\u003eS\u003c/sub\u003e and \u003cem\u003e\u0026eta;\u003c/em\u003e\u003csub\u003eR\u003c/sub\u003e are the values of refractive index for the respective solvent used for the sample and reference.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\n \u003ch2\u003e2.2. Preparation of (NE, NE)-4,4\u0026rsquo;-methylenebis(N-(pyren-1-ylmethylene)aniline) (HL)\u003c/h2\u003e\n \u003cp\u003eThe yellow colored fluorescent ligand was prepared by adopting same procedure of Schiff base preparation via one pot synthetic strategy by mixing two equivalent of 1-pyrene carbaldehyde and one equivalent of 4,4\u0026rsquo;diamino diphenyl methane in dry methanol with respective yield 95% yield, M.P. 175\u0026thinsp;\u0026plusmn;\u0026thinsp;5\u003csup\u003e◦\u003c/sup\u003e C has been shown in Scheme 1. The TOF MS ES\u003csup\u003e+\u003c/sup\u003e spectral study of \u003cstrong\u003eHL\u003c/strong\u003e contains one molecular ion intense peak (L\u0026thinsp;+\u0026thinsp;H )\u003csup\u003e+\u003c/sup\u003e.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\n \u003ch2\u003e2.3. Theoretical Interpretation\u003c/h2\u003e\n \u003cp\u003eTo understand the electronic structures of \u003cstrong\u003eHL\u003c/strong\u003e, we carried out density functional theory (DFT) and time dependent density functional theory (TDDFT) calculations with the B3LYP/6\u0026ndash;31\u0026thinsp;+\u0026thinsp;G(d,p) method basis set using the Gaussian 03 program. The optimized geometry and the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of HL is presented in Fig. UV-vis spectra of L was calculated using the TDDFT method in THF. Calculated absorption peaks had agreed well with the experimentally observed peaks (Tables). In case of L, the transition from HOMO to LUMO, HOMO-1 to LUMO, HOMO-1 to LUMO\u0026thinsp;+\u0026thinsp;1 and HOMO-3 to LUMO had contributed mainly to the excitation at 397, 388, 377 and 346 nm respectively (\u003cstrong\u003eSupplementary Tables\u0026nbsp;1 to 3\u003c/strong\u003e). LUMO\u0026thinsp;+\u0026thinsp;1, HOMO-3 to LUMO and HOMO-5 to LUMO respectively (\u003cstrong\u003eSupplementary Tables\u0026nbsp;1 to 3\u003c/strong\u003e\u003cem\u003e)\u003c/em\u003e. The transitions below 300 nm correspond to admixture of imine to pyrene charge transfer and inter-pyrenyl charge transfer whereas transitions above 300 nm correspond to inter pyrene charge transfer. Due to adjacent conjugated pyrene group it is tough to transfer charge from imine to farther pyrene group overcoming the high energetic barrier of middle aliphatic methylene group. So imine to pyrene charge transfer is high energetic process. Moreover presence of two pyrene groups on different planes minimizes the charge delocalization which further makes it a high energetic process. DFT studies support the fact and in this case pyrene to imine charge transfer is an energetically favorable transition.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"3. Results and discussions","content":"\u003cp\u003e\u003cstrong\u003e3.1. Photophysical properties of (NE,NE)-4,4\u0026rsquo;-methylenebis(N-(pyren-1- ylmethylene)aniline)\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn\u0026nbsp;FTIR\u0026nbsp;spectrum\u0026nbsp;\u003cstrong\u003e\u003cem\u003eH\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u003cem\u003eL\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eshows n(C=N) band at 1584 cm\u003csup\u003e-1\u003c/sup\u003e (\u003cstrong\u003eSupplementary Fig S\u003csub\u003e1\u003c/sub\u003e\u003c/strong\u003e). The \u003csup\u003e1\u003c/sup\u003eH NMR spectral data of \u003cstrong\u003e\u003cem\u003eHL\u003c/em\u003e\u0026nbsp;\u003c/strong\u003eshows signals for imine \u0026ndash;CH proton at 11.53 ppm. The pyrene protons show signal at 7.2-8.06 ppm. Meanwhile aliphatic methylene protons show signal at 3.5 ppm.\u003cstrong\u003e\u0026nbsp;(\u003cem\u003eSupplementary Fig S\u003csub\u003e2\u003c/sub\u003e\u003c/em\u003e).\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eElemental\u0026nbsp;analysis:\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003ecalculated % (C, 90.67; H, 4.50; N, 4.823); found (C, 91; H, 4.11;N,4.89)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eTOF\u0026nbsp;MS\u0026nbsp;ES\u003csup\u003e+\u003c/sup\u003e:\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eCalculated for C\u003csub\u003e47\u003c/sub\u003eH\u003csub\u003e30\u003c/sub\u003eN\u003csub\u003e2\u003c/sub\u003e (L+H)\u003csup\u003e+\u003c/sup\u003e(m/z): 623; found: 623\u003cstrong\u003e\u0026nbsp;(\u003cem\u003eSupplementary Fig S\u003csub\u003e3\u003c/sub\u003e\u003c/em\u003e)\u003c/strong\u003e.This has been justified from TDDFT Study \u003cstrong\u003e(\u003cem\u003eFig 3.).\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2. \u003cem\u003eAggregation induced emission enhancement (AIEE\u003c/em\u003e)\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTHF solution of HL responds intense absorption band at 250-280 nm in association with transitions at 320\u0026ndash;415 nm (\u003cstrong\u003e\u003cem\u003eSupplementary Fig S\u003csub\u003e4\u003c/sub\u003e\u003c/em\u003e\u003c/strong\u003e) The absorption peak nearly at 400 nm may be originated from \u0026pi;-\u0026pi;* transition due to thorough conjugation of \u0026nbsp; multiple aromatic rings of imine functionalized pyrene unit. Gradually addition of water (10% to 80%) to its THF solution results amazing enhancement of optical density at 250-280 nm while drastically diminishes the value at 400 nm presumably to initiate agglomeration \u003cstrong\u003e(\u003cem\u003eSupplementary Fig S\u003csub\u003e4\u003c/sub\u003e\u003c/em\u003e).\u0026nbsp;\u003c/strong\u003eIn\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003efluorescence spectroscopic measurement, THF solution of HL exhibits red shift of emission maxima (475nm) with many fold enhancement of intensity(\u003cstrong\u003e\u003cem\u003eFig 1.\u003c/em\u003e)\u003c/strong\u003e after addition of water (upto 95%) attribute to aggregation induced emission enhancement (AIEE ) operating through restricted intra molecular rotation (RIR) of bulky and stereo-chemical rigid imine mediated pyrene motif. The quantum yield increment of the sample (\u0026Phi;, 0.025 to 0.44) as a linear function of water concentration (percentage) and isolation of aggregated nano material through SEM imaging confirms the above RIR mechanism of emission enhancement phenomenon(\u003cstrong\u003e\u003cem\u003eFig 2a \u0026amp; 2b.\u003c/em\u003e)\u003c/strong\u003e.\u0026nbsp;\u003c/p\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003ePyrene appended luminophores are excellent emissive in nature. Here, we have synthesized and characterized pyrene appended Schiff base, (NE,NE)-4,4\u0026rsquo;-methylenebis(N-(pyren-1-ylmethylene)aniline) (\u003cb\u003eHL\u003c/b\u003e). It shows aggregated induced emission enhancement through restricted intra-molecular rotation upon addition of water to THF mixture (4:1, v/v) with significant quantum yield (Φ) enhancement. Complete Aggregation has been confirmed by SEM analysis. DFT, TD-DFT calculation has been employed to explain the spectral properties.\u003c/p\u003e "},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eDr. Uttam Panda prepared the manuscript and performed all experiments, data collection and interpretation. Mr. Rajat Kumar Sahoo assisted with me regarding SEM imaging and analysis.\u003c/p\u003e\u003ch2\u003eAcknowledgments\u003c/h2\u003e \u003cp\u003eFinancial support from Council of Scientific and Industrial Research for fellowship of Dr. Uttam Panda (grant No. 01(2731)/13/EMR-II) and Infra structure support from Jadavpur University and BCET is thankfully acknowledged. The authors have no conflict of interest\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003e\u0026ldquo;Data is provided within the manuscript and supplementary information files\u0026rdquo;\u003c/p\u003e\n\u003ch2\u003eSupporting Materials\u003c/h2\u003e\n\u003cp\u003eAll spectroscopic figures and DFT, TD-DFT details along with experimental writeup data analyses are given in Supplementary Materials Section \u003cem\u003e(\u003cstrong\u003eFigs S1- S4 \u0026nbsp;and Tables 1 to 3\u003c/strong\u003e)\u003c/em\u003e. \u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eForster T, Kasper KZ (1955) Elektrochem 59:976\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBaxter JB (2012) Commercialization of dye sensitized solar cells: Present status and future research needs to improve efficiency, stability, and manufacturing. 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Sci., 2012, 37, 182\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Schemes","content":"\u003cp\u003eSchemes 1 and 2 are available in the Supplementary Files section\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"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":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Pyrenenyl Schiff base, J-aggregates Emission, DFT calculation","lastPublishedDoi":"10.21203/rs.3.rs-6450767/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6450767/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003ePyrene mediated fluorescent chromophore manifests aggregation induced emission enhancement property followed by discotic nano-aggregates formation in THF- water medium (1:4). 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