The Effect of C–H···N Interactions on Crystal Structure and Thermal Properties of Two Novel Diamine Schiff Bases Derived from Terephthaldialdehyde

Dedicated to the memory of Professor Ljubo Goli~ Two novel potential bridging ligands derived from terephtaldialdehyde, namely 1,4-bis((pyridine-3-ylimi-no)methyl)benzene (1) and 1,4-bis-((1-benzylpiperidin-4-ylimino)methyl)benzene (2), were prepared by the Schiff ba-se condensation. They were characterised by means of IR spectroscopy, thermal analysis and also by powder and single-crystal X-ray diffraction. The molecules of 1 form 1D chains by intermolecular C–H···N interactions. The molecular conformation of 2, governed by intramolecular C–H···N interactions, does not permit formation of intermolecular inte-ractions analogous to those in 1. As a consequence, 2 has a markedly lower melting point and fusion enthalpy than 1, alt-hough its molecular weight is almost double that of 1