Intermolecular interactions in crystal structure, Hirshfeld surface, characterization, DFT and thermal analysis of 5-((5-bromo-1H-indol-3-yl)methylene)-1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione indole

Abstract

Condensation reaction of 5-bromo-1H-indole-3-carbaldehyde and 1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione in ethanol under reflux conditions furnished the formation of 5-((5-bromo-1H-indol-3-yl)methylene)-1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione indole in a very good yield. The desired compound is characterized by spectroscopic and thermal tools, additionally the structure was confirmed by X-ray single crystal diffraction. Visually analysis of desired crystal structure using Hirshfeld surface revealed several short intermolecular connections on the molecule surface while the 2D finger-print draw evaluated the atom-to-atom interactions percentages.The structures of the monomer and the dimer of the product that are obtained from the B3LYP/6-31G(d,p) molecular geometry optimizations were compared with the XRD experimental one. Electronic spectra are assigned on the basis of the TD-DFT results and the molecular orbital (MO) energy level diagrams showing the different MOs included in these transitions are explored. The electrophilic and nucleophilic regions are shown using molecular electrostatic potential map. The GIAO method is used to compute and compare the NMR chemical shifts. The desired organic compound revealed a good thermal stability up to 215 °C.