Co-crystallisation of 2,2′-dithiodibenzoic acid with the isomeric n-pyridinealdazines, n = 2, 3 and 4: supramolecular polymers and the influence of steric factors upon aggregation patterns

Abstract

The structure of the 1:1 co-crystal formed between the dicarboxylic acid, 2,2′-dithiodibenzoic acid, and each of the isomeric 3- and 4-pyridinealdazines features a supramolecular zig-zag chain constructed about the O–Hacid⋯Npyridine synthon. By contrast, using the same experimental conditions, only a 2:3 co-crystal could be formed when the isomeric 2-pyridinealdazine was used. Here, a pentamer is found, stabilised by the O–Hacid⋯Npyridine synthon and these associate to form a supramolecular chain via C–H⋯π contacts. Theory shows no significant differences in the basicity of the pyridine-nitrogen atoms leading to the conclusion that it is the steric congestion related to the relative disposition of the 2-pyridine nitrogen that is responsible for the observed behaviour.