Multiparametric evaluation of structure-photophysical activity correlation: A case study of pyrene-tethered chalcone.

Abstract

Molecular structures with unique functionalities show interesting photophysical properties. The structure-photophysical activity correlation of synthesized pyrene tethered chalcone (PTC) molecule was envisaged from its solvatochromic shift in 14 solvents of nonpolar, polar-protic and polar-aprotic nature. Analysis of PTC solvatochromism using the Taft and Catalan models indicates an increase in the excited state dipole moment. PTC molecule has a carbonyl group and pyridine nitrogen as electronically distinct regions of Lewis acid base behavior and pH sensitivity. A complete quenching of fluorescence intensity of PTC was observed on exposure to HCl fumes, concomitant with orange-to-black color change which upon exposure to NH3 vapors was reversed, corroborating reversible vapochromism. Computational studies of FMO and ESP analysis indicate an intramolecular charge transfer and Lewis acid base reactivity as underlying mechanisms of observed photophysical properties and vapochromism, respectively.