Interplay of Inter- and Intramolecular Interactions in Crystal Structures of 1,3,4-Thiadiazole Resorcinol Derivatives

Abstract

Five new 1,3,4-thiadiazole derivatives have been synthesized, and their crystal structures have been determined by single crystal X-ray diffraction. The influence of substituents on molecular geometry and the three-dimensional arrangement of molecules has been studied by means of single crystal X-ray diffraction, fluorescence, UV–vis spectroscopy, and computational methods. The 1,3,4-thiadiazole derivatives occur in two possible conformations in their crystal lattices: with the ortho-hydroxyl group of the resorcyl ring pointing toward the S or the N atoms from the 1,3,4-thiadiazole ring. In the latter conformation, an intramolecular hydrogen bond is created which is energetically favorable for the isolated molecule as confirmed by theoretical calculations. However, for the molecules in the crystal structures in the former conformation, some intermolecular interactions between the neighboring molecules are strong enough to overrule the intramolecular OH···N hydrogen bond. In the case of one of the 1,3,4-th...