Experimental and theoretical insights into the enhanced intramolecular charge transfer fluorescence of a 3(2H)-furanone based D-π-A compounds tailored with dialkyl chains

As a continuance of our search for novel derivatization reagents, two new compounds possessing di-methyl and di-ethyl group at the phenyl ring of 3(2H)-furanone ring system have been designed and synthesized. The influences of different factors modulating the solvatochromic fluorescence responses of both dyes are discussed in detail. The maximum wavelengths at absorption and emission spectra, Stokes shift, quantum yields, mean fluorescence decay times, radiative and nonradiative decay constants have been determined. It is shown that the expansion of D-π-A architecture with di-alkyl groups substantially increases+ the optical properties of title compounds than the unsubstituted ones, which was synthesized previously via our research. Further, using time-dependent density functional theory (TD-DFT) calculations it turned out that the donor - acceptor groups at both ends and -C = C- linker imposes a hybridized local excitation charge transfer (HLCT) with the terminal –COOH group could serve to bind targeted analytes having –NH₂ or –OH group.