Design of a Series of Isostructural Co-Crystals with Aminopyrimidines: Isostructurality through Chloro/Methyl Exchange and Studies on Supramolecular Architectures

A series of 17 co-crystals involving 2-amino-4-chloro-6-methyl pyrimidine/2-amino-4,6-dimethyl pyrimidine with various carboxylic acids, C7H5O2-R (where R = H, Cl, CH3, NO2, OCH3, COOH) and C9H8O2, have been prepared in which the analogues differ only with respect to chlorine and methyl groups. The basis of this work is the formation of isostructural co-crystals based on the chloro/methyl interchange. The results show good success in the harvest of isostructural compounds. Isostructurality calculations have been carried out in order to substantiate these results. Apart from this some of the compounds have been identified to show good resemblance in their structure, yet do not have any relation based on chloro/methyl interchange. This is explained by the fact that all the co-crystals in the present study tend to form one common supermolecule: a linear heterotetramer. This supermolecule is known to be the most stable and reliable heterotetramer formed between an aminopyrimidine and benzoic acid, according to a recent report, which is believed to be responsible for the isostructurality other than chloro/methyl exchange.