Synthesis and structural characterization of s-triazine derivatives and their photophysical properties

• Molecular conformation of four s - triazine crystals has been evaluated. • Molecular overlapping of crystals and DFT optimized geometry shows high similarity. • Band gap has been calculated using DFT calculations. • Stokes shift has been calculated from absorption and emission spectra. In the current work, crystals of four s -triazine analogues were examined by single X-ray diffraction study. Intermolecular N7—H7…O3 hydrogen bonding patterns in 1 form chain-like supramolecular structures that extends along the crystallographic b axis. These chains are further linked by intermolecular π ring2 … π ring3 interactions that propagate diagonally with respect to the crystallographic ab plane; thus, forming a two-dimensional supramolecular structure. In 2 and 3 , intermolecular N—H…O were observed between the H7 atom of the amine group and O4 atom of the methanol molecule. In 4 , the same intramolecular C—H…N hydrogen bonds mentioned in 2 and 3 were found. Hirshfeld surface explained the O…H and N…H contacts contributing towards hydrogen bonding. The dihedral angles showed slight deviation, and this was related to the natural atomic charges present on the atoms in the molecule. Band gap was found to be lowest in case of 2 (3.95 eV) and highest in case of 1 (4.57 eV) depicting its highest and lowest reactivity, respectively. UV–vis and fluorescence reveal largest Stokes shift in case of 2 and lowest in case of 4 .