Synthesis and Characterizations of Novel Isatin-s-Triazine Hydrazone Derivatives; X-ray Structure, Hirshfeld Analysis and DFT Calculations

A novel series of isatin-s-triazine hydrazone derivatives has been synthesized and reported herein. The synthetic methodology involved the reaction of s-triazine hydrazine precursors with isatin derivatives in the presence of CH3COOH as a catalyst and EtOH as solvent to afford the corresponding target products 6a-e in high yields and purities. The characterization data obtained from elemental analysis, FT-IR, NMR (1H- and 13C-) were in full agreement with the expected structures. Furthermore, an X-ray single crystal diffraction study of one of the target s-triazine hydrazone derivatives, 6c confirmed the structure of the desired compounds. It crystallized in the triclinic crystal system and P-1 space group with a = 10.3368(6) Å, b = 11.9804(8) Å, c = 12.7250(5) Å, α = 100.904(4)°, β = 107.959(4)° and γ = 109.638(6)°. The different non-covalent interactions which contributed in the molecular packing of 6c were analyzed using Hirshfeld analysis. The molecular packing of the organic part of the crystal structure showed important O…H (7.1%), C…H (16.4%), C…C (1.6%), H…H (34.8%), N…H (8.0%) and C…N (4.0%) interactions while for the crystal solvent, the O…H (21.3%), H…H (61.2%) and N…H (8.1%) contacts are the most significant. The studied compound 6c is polar and has a net dipole moment of 5.6072 Debye based on DFT study.