Construction of Supramolecular Assemblies from Substituted Pyrazoles and Pyromellitic Acid: Rational Analysis of the Synthons and Theoretical Studies

Seven supramolecular assemblies of benzene-1,2,4,5-tetracarboxylic acid (pyromellitic acid, H4BTtC) and various pyrazoles viz., pyrazole (PzH), 3,5-dimethylpyrazole (PzMe2H), 3,5-diisopropylpyrazole (PziPr2H), 3-tert-butyl-5-isopropylpyrazole (PztBu,iPrH), 3-phenyl-5-methylpyrazole (PzPh,MeH), 3-cumyl-5-methylpyrazole (PzCum,MeH), 3,3′,5,5′-tetramethyl-4,4′-bipyrazole (BPzH2) have been synthesized. Proton transfer was observed in all the cases except with 3-phenyl-5-methylpyrazole (PzPh,MeH). Theoretical studies were also performed to analyze the effect of various substituted pyrazoles on hydrogen-bond interaction energy of adducts. Energies of the resulted SOFs were also calculated to correlate their stability and occurrence with the different substituent present on the pyrazoles. Supramolecular assemblies of pyromellitic acid with pyrazoles have been synthesized.