STRUCTURAL CHARACTERIZATION OF DICYANIDOBIS( <i>N</i>, <i>N</i>''-DIMETHYLTHIOUREA-κ <i>S</i>)CADMIUM(II)
A reaction between caffeine (caff) and dipicolinic acid = 2,6-pyridine dicarboxylic acid (pydc.H <sub>2</sub>) in water results in the formation of a cocrystal compound (pydc.H <sub>2</sub>.H <sub>2</sub>O)(caff) 1. The characterization of the resulting crystallohydrate is performed using <sup>1</sup>H, <sup>13</sup>C NMR and IR spectroscopy and X-ray crystallography. X-ray crystal structure analysis reveals the presence of both starting materials and water in the lattice. It also indicates intensive intermolecular H-bonding interactions between carboxylic acid, caffeine, and water as well as π—π stacking between the pydc.H <sub>2</sub> and caff rings as constituents of the cocrystal. The hydrogen bonding and non-covalent interactions play roles in the formation of the cocrystal. The crystal system is triclinic with the space group P- 1 and two formula units per unit cell. The unit cell parameters are <i>a</i> = 6.906(2) Å, <i>b</i> = 8.451(3) Å, <i>c</i> = 14.68 (4) Å with α = 81.51(3°), β = 78.47(3°), and γ = 78.14(3°). The final <i>R</i> value is 0.0660 for 7943 measured reflections.