Femtosecond Time-Resolved Raman Spectroscopy Reveals Structural Evidence for meta Effect in Stilbenols

Kayal, Surajit (2018) Femtosecond Time-Resolved Raman Spectroscopy Reveals Structural Evidence for meta Effect in Stilbenols. In: JOURNAL OF PHYSICAL CHEMISTRY A, 122 (19). pp. 4601-4608.

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Abstract

The met a effect in substituted aromatics plays a crucial role in their excited-state photophysical properties. Meta-substituted hydroxyarenes such as naphthols, stilbenols, and chromophoric constituents of green fluorescent proteins show unusual photoacidity and enhanced fluorescence lifetime and quantum yield when compared to their para-derivatives. Variation in the excited state features of the meta-derivatives when compared to the para-derivatives in stilbenols has been attributed to the enhanced torsional barrier for interconversion between the planar and the twisted perpendicular forms. Herein, we employed femtosecond time-resolved Raman spectroscopy to provide the direct structural evidence for the enhanced torsional barrier in meta-stilbenol. The Raman band profiles of the olefinic C=C stretch related to the torsional motion are found to decay with time constants of similar to 750 and similar to 13 ps in meta-stilbenol and para-stilbenol respectively, unraveling the structural evidence for the observed enhanced photoacidity originating from enhanced rates of excited-state proton transfer. Further, time-resolved fluorescence measurements are performed to elucidate the relaxation pathways of the excited states of the stilbenols.

Item Type:	Journal Article
Publication:	JOURNAL OF PHYSICAL CHEMISTRY A
Publisher:	AMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 USA
Additional Information:	Copy right of this article belong to AMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 USA
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited:	13 Jun 2018 15:26
Last Modified:	13 Jun 2018 15:26
URI:	http://eprints.iisc.ac.in/id/eprint/60005

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