CSIR Central

Spectral Response of 4-Methyl-2,6-dicarbomethoxyphenol, an Excited-State Intramolecular Proton-Transfer Probe in Cyclohexane-Ethanol Mixtures: Signatures of Medium Microheterogeneity

IR@CGCRI: CSIR-Central Glass and Ceramic Research Institute, Kolkata

View Archive Info
 
 
Field Value
 
Title Spectral Response of 4-Methyl-2,6-dicarbomethoxyphenol, an Excited-State Intramolecular Proton-Transfer Probe in Cyclohexane-Ethanol Mixtures: Signatures of Medium Microheterogeneity
 
Creator Misra, Ramprasad
Bhattacharyya, S P
Mandal, Abhijit
 
Subject Crystal Chemistry, Thermodynamics, Phase Equilibria
 
Description In this paper, we explore the role of microscopic heterogeneity of the medium on the spectral response of an excited-state proton-transfer (ESIPT) probe, namely, 4-methyl-2,6-dicarbomethoxyphenol (CMOH) using steady-state and time-resolved emission spectroscopy. The mixtures of two solvents with widely different properties, viz., cyclohexane, a nonpolar, and ethanol, a polar protic solvent, were used as microheterogeneous media for spectroscopic studies. Dual fluorescence (normal and tautomer fluorescence) is observed in the nonpolar solvent (cyclohexane), while only a single peak is observed in the protic solvent, ethanol. The spectral responses of CMOH in the binary mixtures have been found to be dependent on the solvent composition and excitation wavelength. The emission spectral properties of CMOH in the cyclohexane ethanol mixture have been seen to be superposition of spectral properties in their bulk counterparts, indicating the presence of microscopic heterogeneity in the system. A zwitterionic species of CMOH appears to have been detected in binary solvent mixtures with higher ethanol content only through low-energy excitations. The species is converted into an anionic species as excitation energy increases. Density functional theory calculations indicate that two intramolecularly hydrogen bonded rotamers of CMOH have a small energy difference. The formation of a hydrogen bonded 1:1 molecular cluster of CMOH with ethanol has been investigated in the ground state at the same level of theory. Our findings are expected to shed light on the mechanism of many acid base reactions occurring in microscopically inhomogeneous media that often mimic many biologically relevant processes.
 
Publisher AMER CHEMICAL SOC
 
Date 2011-10
 
Type Article
PeerReviewed
 
Format application/pdf
 
Identifier http://cgcri.csircentral.net/644/1/mandal%2Ca%2D2011.pdf
Misra, Ramprasad and Bhattacharyya, S P and Mandal, Abhijit (2011) Spectral Response of 4-Methyl-2,6-dicarbomethoxyphenol, an Excited-State Intramolecular Proton-Transfer Probe in Cyclohexane-Ethanol Mixtures: Signatures of Medium Microheterogeneity. JOURNAL OF PHYSICAL CHEMISTRY B, 115 (41). pp. 11840-11851. ISSN 1520-6106
 
Relation http://cgcri.csircentral.net/644/