Supramolecular, spectroscopic and computational analysis of weak interactions in some thiosemicarbazones derived from 5-acetylbarbituric acid

Abstract

A new series of 5-acetylbarbituric based thiosemicarbazones (TSC) named 5-acetylbarbituric hydrazine-1-carbothioamide (1), N-methyl-(5-acetylbarbituric)hydrazine-1-carbothioamide (2), N-ethyl-(5-acetylbarbituric)hydrazine-1-carbothioamide (3), N,N-dimethyl-(5-acetylbarbituric)hydrazine-1-carbothioamide (4), N'-piperidine-(5-acetylbarbituric)-1-carbothiohydrazide (5) and N'-hexamethyleneimine-(5-acetylbarbituric)-1-carbothiohydrazide (6), has been synthesized from 5-acetylbarbituric acid and N-unsubstituted/substituted thiosemicarbazides. The synthesized compounds were well characterized by elemental analyses, FT-IR, 1H, 13C NMR and mass spectroscopic methods. Three-dimensional molecular structures of three compounds (1⋅DMSO, 2 and 6⋅H2O) were determined by single crystal X-ray crystallography, and an analysis of their supramolecular structure was carried out. The supramolecular features of the X-ray structure were also studied using Hirshfeld surface analysis. Finally, H-bonding networks observed in the solid state X-ray structures of 1⋅DMSO, 2, and 6⋅H2O and unconventional π-stacking dimers in 6⋅H2O were further analyzed by DFT calculations in combination with molecular electrostatic potential surfaces and combined QTAIM/NCIplot computational tools.