Stoichiometric variation in two molecular salts of the anti-tuberculosis drug isoniazid with 2-butynoic acid

The supramolecular reagent isoniazid is a molecule capable of undergoing a number of different heteromeric interactions to form neutral co-crystals. By choosing a suitably acidic carboxylic acid molecule, we have been able to form two molecular salts by altering the ratio of the two reactant molecules by both solution crystallization and mechanochemical means. The two stoichiometric salts are formed by using both similar and different hydrogen bonded interactions to those encountered previously in co-crystals.