From chains to ladders in co-crystals with 2,3-thiophene-15-crown-5, 2,3-naphtho-15-crown-5, and bis-(18-crown-6)-stilbene constructed by weak hydrogen bonding

Abstract

For the first time a series of co-crystals of 2,3-thiophene-15-crown-5 1, 2,3-naphtho-15-crown-5 2, bis-(18-crown-6)-stilbene 3 with dithiooxamide a, 1,2,5-oxadiazole-3,4-diamine b, and 3-nitro-1H-1,2,4-triazole c with compositions 1a, 2a, 2b·H₂2O, 2c, and 3a₂2 were prepared and their structures were studied by X-ray crystallography. The components in the co-crystals demonstrate the different modes of mutual arrangement and contribution of diverse weak interactions to the final architecture. Infinite chains of the alternating component molecules linked by N–H⋯O hydrogen bonds characterise the structures of 1a and 2a, whereas in the case of 3a₂2 formation of the loosely packed ladder-type structure was observed. In 2b·H₂2O the planar naphtho- and oxadiazole moieties demonstrate their edge-to-face arrangement, while in 2c the partially overlapping naphtho- and triazole moieties provide effective face-to-face π–π stacking interactions. The improved synthetic strategy for 1 and 2 is given.