Computational and spectroscopic studies of biologically active coumarin-based fluorophores

We used density functional theory (DFT) calculations to examine the various molecular properties of two coumarin derivatives, namely 4-(5-amino-[1,3,4]thiadiazol-2-ylsulfanylmethyl)-7-methyl-chromen-2-one and 4-(5-amino-[1,3,4]thiadiazol-2-ylsulfanylmethyl)-7-methoxy-chromen-2-one at different levels of theory and basis sets. The calculated highest occupied molecular orbital and lowest unoccupied molecular orbital energies revealed that the investigated molecules were chemically active with a tendency for molecular interactions. The theoretical vibrational frequencies of these molecules were found to be consistent with the experimentally obtained frequencies. Moreover, solvatochromic measurements indicated no significant change in absorption spectral peak by varying the polarity of solvent. Under the same conditions we found that there was a red shift of 39 nm in the fluorescence spectral peak with increase in solvent polarity. The solvatochromic data were used to estimate excited dipole moments and the change in dipole moment was interpreted based on resonance structure of molecules.

Effect of Concentration of TiO2 Nanoparticles on Thiadiazole Derivative and Their Molecular Docking Study

In the present work, we report the synthesis of TiO2 nanoparticles by hydrothermal method using titanium isopropoxide. The synthesized TiO2 nanoparticles were investigated by Powder X-ray diffraction, FE-SEM with EDX, Photoluminescence, UV-Visible absorption and Fluorescence emission spectroscopy. Fluorescence intensity and absorption values of 4-[5-(2,5-Dimethyl-pyrrol-1-yl)-[1,3,4]thiadiazol-2-ylsulfanylmethyl]-6-methoxy-chromen-2-one (DTYMC) molecule decreases with adding the concentration of TiO2 nanoparticles. Stern-Volmer equation for steady state method is found to be linear and its co-relation coefficient is found to be r = 0.88, which indicates the presence of dynamic quenching. Binding orientations of the DTYMC ligand with targeted proteins are Thymidylate synthase (TS) - PDB ID: 1JU6, The type II topoisomerases (TOP2α) - PDB ID: 4FM9 and Human thymidine phosphorylase (hTP) - PDB ID: 2WK6. The obtained result suggests that, the DTYMC molecule exhibits inhibitory activity against the overexpression of TS receptor which causes non-small cell lung cancer (NSCLC). Antimicrobial study of TiO2 NPs has been determined.