Hydrogen-Bonded One- and Two-Dimensional Hybrid Water-Chloride Motifs

The organic salt α,α′-p-xylene-N,N′-bis­(3-hydroxymethylpyridinium) dichloride (1) has been crystallized in two hydrated forms, namely, 1A and 1B, with two and three water molecules as lattice guests, respectively. These supramolecular structures were well characterized by various physicochemical techniques such as CHN analysis, IR, thermogravimetric, differential scanning calorimetry, NMR, powder X-ray diffraction, and single crystal X-ray diffraction. Both hydrates are fairly stable and soluble in water and other polar solvents. Structural analysis of 1A and 1B reveals that various hydrogen bonding interactions such as C–H···Cl–, O–H···Cl–, and O–H···O between the cationic organic moiety, chloride anion, and lattice water molecules play a crucial role in stabilizing the zigzag water-chloride infinite chains in 1A and a novel two-dimensional water-chloride [(H2O)10(Cl–)6]n network in 1B. In addition to the above-mentioned hydrogen bonding interactions, strong electrostatic interactions between cation and anion play an important role in assembly of such hybrid networks. Interestingly, dehydration followed by a rehydration process results in the recovery of [(H2O)10(Cl–)6]n water-chloride net leading to the regeneration of 1B in the case of both solvates. The structural studies of both hydrates and their reversible inter conversion via solid–gas reactions and recrystallization experiments provide comprehensive information about cooperative hydrogen bonding behavior of the chosen system.