Design, synthesis and characterization of π-conjugated 2,5-diphenylsubstituted-1,3,4-oxadiazole-based D-π-A-π’-D′ form of efficient deep blue functional materials: Photophysical properties and fluorescence “Turn-off” chemsensors approach

Abstract

This paper primarily deals with the design and synthesis of three novel conjugated organic molecules containing 1,3,4-oxadiazole unit (abbreviated as CHEM-6(a-c)) with Donor-π-Acceptor-π’-Donor’ structures by utilizing palladium catalyzed Suzuki cross coupling reaction. Molecular structures of these compounds were characterized by using various spectroscopic and analytical techniques namely 1H NMR, 13C NMR, FT-IR, GC–MS and elemental analysis. Optical properties of these compounds have been investigated by using UV–visible absorption and fluorescence spectroscopy. Also, the PL investigations on solid state samples (as thin films) were carried out. Furthermore, solvatochromism and Density Functional Theory (DFT) computations are studied in detail. The experimentally measured optical band gap (Egopt) values of compounds CHEM-6a, CHEM-6b and CHEM-6c were determined to be 3.11, 3.03 and 2.70 eV, respectively. The DSC and TGA results revealed that the compounds exhibit good thermal stabilities. Current results indicate that the compounds CHEM-6(a-c) are promising candidates and could play an important role in the field of optoelectronic devices and possibly find potential applications in development of OLEDs. In addition, the compounds CHEM-6(a-c) showed an interesting property of chemical sensing for Hg(II) ion which can be clearly observed by naked eyes from the changes in solution color and fluorescence (under UV excitation).