Multicomponent solids of uracil derivatives - orotic and isoorotic acids

Cocrystallization of two multifunctional structural isomers viz. orotic and isoorotic acids was explored with a series of amine and pyridine-based coformers. The system has been chosen in such a way so that robustness of the acid pyridine synthon was tested against competing amine pyridine and carbonyl pyridine synthons. Here, we report the structural characterization and solubility measurements of ten solids which include three cocrystals, one salt cocrystal, four salts and two salt hydrates. All multicomponent solids showed significant improvement in solubility in comparison to the acids and also showed a strong correlation between the percentage of the O H interaction and solubility. The Δp K a rule is validated in the structural landscape by considering all components of the matrix together. Cocrystallization of two multifunctional structural isomers viz. orotic and isoorotic acids was explored with a series of amine and pyridine-based coformers.