{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,22]],"date-time":"2026-10-22T12:42:48Z","timestamp":1792672968748,"version":"4.5.0"},"reference-count":77,"publisher":"American Chemical Society (ACS)","issue":"42","license":[{"start":{"date-parts":[[2026,10,13]],"date-time":"2026-10-13T00:00:00Z","timestamp":1791849600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100002241","name":"Japan Science and Technology Agency","doi-asserted-by":"publisher","award":["Z2024L1015054"],"award-info":[{"award-number":["Z2024L1015054"]}],"id":[{"id":"10.13039\/501100002241","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Department of Biotechnology , Ministry of Science and Technology","award":["BT\/NER\/143\/SP44675\/2023"],"award-info":[{"award-number":["BT\/NER\/143\/SP44675\/2023"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,10,22]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Excited-state intramolecular proton transfer (ESIPT) processes have attracted much attention due to their applications in sensing, imaging, and solid-state optoelectronic devices. The effect of substitution on ESIPT was studied by synthesizing 2-(4\u2019-(N,N-diethylamino)-2\u2019-hydroxyphenyl)benzimidazole-5-carbonitrile (DEAHBIC). The fluorophore was investigated experimentally in solution and as a powder sample. Theoretical calculations were performed to understand the effect of solvent polarity on the emission behavior. The theoretical studies revealed that not only the shift in equilibrium but also a reduction in ESIPT decrease the tautomer emission in polar environments. The fluorescence quantum yield of DEAHBIC was significantly lower than 2-(2\u2019-hydroxyphenyl)benzimidazole (HBI). The formation of an intramolecular charge-transfer-induced twisted keto form reduced the fluorescence. Time-resolved fluorescence studies revealed that the tautomer emission lifetime was longer than the normal emission in less polar solvents. In contrast to HBI, in more polar solvents the lifetime of the normal emission of DEAHBIC was longer than its tautomer emission. Unlike the electron-withdrawing NO2 group, the cyano substitution reduced ESIPT. In the powder sample, ESIPT was increased, which enhanced the relative intensity of the tautomer emission, but the overall fluorescence quantum yield was reduced. In addition, ESIPT was also investigated in polymer films. The tautomer fluorescence quantum yield was improved in thin films. Studies in polymer thin films are also useful for understanding the microenvironment experienced by the molecule in the polymer film. The tautomer emission wavelength red-shifted and the \u03d5T\/\u03d5N ratio increased in the order polystyrene (PS) &amp;lt; polysulfone (PSF) &amp;lt; poly(methyl methacrylate) (PMMA) &amp;lt; polyvinyl acetate (PVAc) &amp;lt; polyvinyl chloride (PVC).<\/jats:p>","DOI":"10.1021\/acs.jpcb.6c04052","type":"journal-article","created":{"date-parts":[[2026,10,13]],"date-time":"2026-10-13T15:02:17Z","timestamp":1791903737000},"page":"11227-11239","source":"Crossref","is-referenced-by-count":0,"title":["Unveiling Excited-State\nDynamics of 2-(4\u2019-(Diethylamino)-2\u2019-hydroxyphenyl)benzimidazole-5-carbonitrile\nin Solutions, Powder, and Polymer Films: Intramolecular Proton Transfer\nand Charge Transfer"],"prefix":"10.1021","volume":"130","author":[{"given":"Kirti","family":"Yadav","sequence":"first","affiliation":[{"name":"Indian Institute of Technology Guwahati , , North Guwahati , , ,","place":["Guwahati, Assam, India, 781039"]},{"name":"Gifu University , , 1-1, Yanagido , ,","place":["Gifu, Japan, 501-1193"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rajib","family":"Das","sequence":"additional","affiliation":[{"name":"Indian Institute of Technology Guwahati , , North Guwahati , , ,","place":["Guwahati, Assam, India, 781039"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7880-6093","authenticated-orcid":true,"given":"Kazumasa","family":"Funabiki","sequence":"additional","affiliation":[{"name":"Gifu University , , 1-1, Yanagido , ,","place":["Gifu, Japan, 501-1193"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5543-3597","authenticated-orcid":true,"given":"G.","family":"Krishnamoorthy","sequence":"additional","affiliation":[{"name":"Indian Institute of Technology Guwahati , , North Guwahati , , ,","place":["Guwahati, Assam, India, 781039"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"316","published-online":{"date-parts":[[2026,10,13]]},"reference":[{"issue":"57","key":"2026102207413779500_cit1","doi-asserted-by":"publisher","DOI":"10.1002\/chem.202301540","article-title":"Excited-State Proton\nTransfer in Luminescent Dyes: From Theoretical Insight to Experimental\nEvidence","volume":"29","author":"Fontes","year":"2023","journal-title":"Chem.\u2013Eur. 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Lumin."},{"issue":"23","key":"2026102207413779500_cit24","doi-asserted-by":"publisher","first-page":"7926","DOI":"10.1039\/D3DT01199B","article-title":"2-Hydroxyphenyl\nBenzimidazoles and Their Boron Complexes:\nSynthesis, Structure, Aggregation-Induced Emission and Picric Acid\nSensing","volume":"52","author":"Arumugam","year":"2023","journal-title":"Dalton Trans."},{"issue":"1","key":"2026102207413779500_cit25","doi-asserted-by":"publisher","first-page":"169","DOI":"10.1039\/C5CS00543D","article-title":"Excited-State Intramolecular\nProton-Transfer (ESIPT)-Inspired Solid\nState Emitters","volume":"45","author":"Padalkar","year":"2016","journal-title":"Chem. Soc. Rev."},{"issue":"6","key":"2026102207413779500_cit26","doi-asserted-by":"publisher","first-page":"5134","DOI":"10.1039\/C5RA23261A","article-title":"Effect of Amino Group\non the Excited-State Intramolecular Proton Transfer (ESIPT) Mechanisms\nof 2-(2\u2032-Hydroxyphenyl)Benzoxazole and Its Amino Derivatives","volume":"6","author":"Li","year":"2016","journal-title":"RSC Adv."},{"issue":"1","key":"2026102207413779500_cit27","doi-asserted-by":"publisher","first-page":"65","DOI":"10.1007\/s43630-023-00499-x","article-title":"The Solvent-Regulated Excited State\nReaction Mechanism of 2-(2\u2032-Hydroxyphenyl)Benzothiazole Aggregates","volume":"23","author":"Jain","year":"2024","journal-title":"Photochem. Photobiol. Sci."},{"issue":"42","key":"2026102207413779500_cit28","doi-asserted-by":"publisher","first-page":"26297","DOI":"10.1039\/D2CP03007A","article-title":"Spectroscopic and Mechanistic\nInsights into Solvent Mediated Excited-State Proton Transfer and Aggregation-Induced\nEmission: Introduction of Methyl Group onto 2-(o-Hydroxyphenyl)benzoxazole","volume":"24","author":"Li","year":"2022","journal-title":"Phys. Chem. Chem. Phys."},{"issue":"36","key":"2026102207413779500_cit29","doi-asserted-by":"publisher","first-page":"11154","DOI":"10.1021\/ja047815i","article-title":"Strong\nSolvatochromic Fluorescence from the Intramolecular\nCharge-Transfer State Created by Excited-State Intramolecular Proton\nTransfer","volume":"126","author":"Seo","year":"2004","journal-title":"J. Am. Chem. Soc."},{"issue":"36","key":"2026102207413779500_cit30","doi-asserted-by":"publisher","first-page":"8323","DOI":"10.1021\/jp804216u","article-title":"Spectroscopy\nand Femtosecond Dynamics of Excited-State Proton Transfer Induced\nCharge Transfer Reaction","volume":"112","author":"Hsieh","year":"2008","journal-title":"J. Phys. Chem. A"},{"issue":"18","key":"2026102207413779500_cit31","doi-asserted-by":"publisher","first-page":"5618","DOI":"10.1021\/jp909438p","article-title":"Excited State\nIntramolecular Proton Transfer and Charge Transfer Dynamics of a 2-(2\u2032-Hydroxyphenyl)Benzoxazole\nDerivative in Solution","volume":"114","author":"Kim","year":"2010","journal-title":"J. Phys. Chem. 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Liq."},{"issue":"35","key":"2026102207413779500_cit36","doi-asserted-by":"publisher","first-page":"17624","DOI":"10.1021\/acs.jpcc.3c04543","article-title":"Balancing the Push\u2013Pull Effect on the Synthesis\nand Fluorescent Properties of New ESIPT Dyes for Thin Film Applications","volume":"127","author":"Soares","year":"2023","journal-title":"J. Phys. Chem. 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