Hydrothermal synthesis, experimental and theoretical characterization of a novel cocrystal compound in the 2:1 stoichiometric ratio containing 6-methyluracil and dipicolinic acid.

This paper reports the hydrothermal synthesis, experimental and theoretical studies of a novel cocrystal compound in the 2:1 stoichiometric ratio of 6-methyluracil (6mu) and dipicolinic acid (pydcH(2)) formulated as [6mu](2)[pydcH(2)] (1), for the first time. DFT calculations were performed to access the most possible geometry of the title cocrystal compound. All calculations were carried out with the B3LYP hybrid density functional level and 6-311+G(d,p) basis sets. The vibrational frequencies together with the (1)H and (13)C NMR chemical shifts have been calculated on the fully optimized geometry of 1. The theoretical results are in good agreement with the experimental and solution data. The theoretical, solution, and experimental (elemental analysis, mass spectrometry, FTIR, (1)H and (13)C NMR spectroscopies) results confirmed our proposed structure for 1 in the 2:1 stoichiometric ratio of 6mu and pydcH(2), respectively. The protonation and equilibrium constants of 6mu and pydcH(2) and constituent systems were determined by potentiometric studies and the corresponding distribution diagrams depicted.