Novel Bis-Thiadiazole Compound: Synthetic, Optical Properties, and Computational Calculations

In this study, a novel compound, diethyl 5,5'-(isophthaloylbis(hydrazin-2-yl-1-ylidene))(5E,5'E)-bis(4-phenyl-4,5-dihydro-1,3,4-thiadiazole-2-carboxylate), was designed and synthesized with a moderate yield. The structure of the bis-thiadiazole compound was elucidated through nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), mass spectrometry (MS), and elemental analysis techniques. Computational quantum mechanical calculations at the DFT level were employed to investigate its structure, including frontier molecular orbital (FMO), natural bond orbital (NBO) analysis, molecular electrostatic potential (MESP) analysis, and excited state calculations. The crystallographic structure of the bis-thiadiazole thin film was explored by X-ray diffraction (XRD) investigation. Absorbance spectra and photoluminescence (PL) of the investigated compound were used to deduce the molar absorption coefficient $$({{\varepsilon }_{{{\text{molar}}}}})$$ , the optical band transitions, and the emission peak position. The optical gap energy ( $$E_{{{\text{gap}}}}^{{{\text{opt}}}}$$ ) of bis-thiadiazole organic molecules in dimethyl sulfoxide (DMSO) and bis-thiadiazole thin films was estimated using the absorbance spectrum fitting (ASF) approach. The current research has been focused on the development of novel, effective, and selective organic compounds for potential applications in various modern fields, including optical materials, as well as in medical and biological research.