Exploration of ESIPT Mechanism in Different Quinone Fused Heterocyclic Conjugates
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Date
2021-09
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CCSHAU, Hisar
Abstract
ESIPT is a key aspect in many fields of science which has been extensively used in the design and synthesis of fluorescent probes for the real time monitoring of environmentally and biologically relevant species. Molecules with hydrogen bonding capabilities have the potential to exhibit dual fluorescence due to prevailing ESIPT phenomenon in them. In the present work, a series of quinone fused imidazoles have been designed and the feasibility of proton transfer was investigated using DFT and TD-DFT based theoretical approach. Initially, conformational search was done in order to explore the most stable conformer for quinone fused imidazoles (N1-N6). The ground state geometries were utilized to evaluate the global reactivity descriptors in different solvent systems of varying polarity. The structural features in the excited state were investigated for those compounds which have probability of H-bonding in their ground state geometry. Potential energy scan was applied over O-Hb bond to explore the feasibility of proton transfer in the excited state of the molecules (N2, N4, N5 and N6). The compounds with established ESIPT phenomenon were synthesized and their photophysical properties were investigated in solvents of different polarity. Dual emission with large stoke shift in the fluorescence spectra of N2, N4, N5 and N6 revealed the presence of ESIPT phenomenon in their excited states.