Synthesis, structural, photo-physical properties and DFT studies of some diarylheptanoids

In the present work, we have described the structures, photo-physical properties and DFT computations of some curcumin type diarylheptanoids (4a–c). These compounds were characterized by multi-spectroscopic techniques including X-ray single crystal of one of the intermediates (3a). The molecular geometries and structural features were configured by DFT -B3LYP/6-31G(d,p) calculations; however, combined 6-31G(d,p)/LANL2Dz basis sets (B3LYP/Gen) were employed in case of bromine and iodine derivatives. Compared to the native curcuminoids, these diarylheptanoids showed blue-shifted optical spectroscopic features in solution; aggregation enhanced emission properties were also noted. The incorporation of halogen atom enhanced thermal stability of the compounds. Aided by Cartesian coordinate displacement of the computed wavenumbers, we have suggested reliable vibrational assignments for the observed infrared fundamentals. The results of this study will be a valuable addition to the growing body of work on the properties of curcuminoids.