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Photophysical characterization and effect of pH on the twisted intramolecular charge transfer fluorescence of trans-2-[4-(dimethylamino)styryl]benzothiazole

Paper ID Volume ID Publish Year Pages File Format Full-Text
27739 44039 2008 10 PDF Available
Title
Photophysical characterization and effect of pH on the twisted intramolecular charge transfer fluorescence of trans-2-[4-(dimethylamino)styryl]benzothiazole
Abstract

Experimental and theoretical photophysical characterization of trans-2-[4-(dimethylamino)styryl]benzothiazole (DMASBT) has been carried out in solutions of different polarities. Steady state fluorescence emission and excitation spectra of DMASBT in the solvents of varying polarities suggest the existence of dual emitting states where locally excited state is responsible for fluorescence in nonpolar solvents; however, in polar solvents fluorescence is from twisted intramolecular charge transfer (TICT) state. Solvatochromic comparison method suggests that the dipolar interactions make the major contribution to the stability of ground as well as excited states with more effect on the latter. Semi-empirical AM1 singly excited configuration interaction (AM1-SCI) calculations support the formation of the TICT state of DMASBT. The twist of the –N(CH3)2 group and the change in its hybridization in the excited state develops a high dipole moment in the S3 state and thereby stabilizing it to give the TICT fluorescence in polar solvents. The TICT fluorescence of DMASBT decreases above the pH value of 3.7 suggesting that hydrogen bonding ability of water molecules becomes efficient above this pH. Results indicate that DMASBT can be a potential sensor based on its remarkably high fluorescence sensitivity towards polarity, viscosity and pH of the medium.

Keywords
Fluorescence; Styrylbenzothiazole; Twisted intramolecular charge transfer; Polarity; Acidity constant; AM1-SCI
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Photophysical characterization and effect of pH on the twisted intramolecular charge transfer fluorescence of trans-2-[4-(dimethylamino)styryl]benzothiazole
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 195, Issues 2–3, 15 April 2008, Pages 368–377
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us