Relativistic two-component time dependent density functional studies and Hirshfeld surface analysis of halogenated arylidenehydrazinylthiazole derivatives

Crystal structures of compounds 2-(2-chlorobenzylidene)hydrazinylthiazole (2a) 2-(2-bromobenzylidene) hydrazineylthiazole (2b) were analyzed with single crystal XRD. Both compounds possess Monoclinic crystal system and P21/n space group. Intermolecular interactions in single crystals were studied with Hirshfeld surface analysis (HSA). Electronic spectrum of 2a and 2b has been studied with two-component relativistic sf-X2C-S-TD-DFT approach and induction of spin-orbit couplings in organic skeleton by bromine and chlorine atoms has been explored. Magnitude of spin-orbit couplings in 2b at B3LYP-D3/x2c-TZVPPall level of theory promises its use as triplet sensitizer in photodynamic therapy and solar light-based fuel cells.