A Two-Dimensional Self-Assembled Proton Transfer Compound Containing Pyridinium-2,6-bis(monothiocarboxylate) and Creatinium Ion Pair: Synthesis, Characterization, Crystal Structure, Solution and Ab initio Studies

A two-dimensional self-assembled proton-transfer compound, (creatH)+(pdtcH)-, L, was synthesized from the reaction of pyridine-2,6-bis(monothiocarboxylic) acid, (pdtcH2), and creatinine, creat, and characterized using IR, NMR, UV spectroscopy and X-ray crystallography. The anionic and cationic components self assemble two-dimensionally via ion-pairing, H-bonding and π-π stacking and, therefore, parallel sheets are formed. The spectrometric and potentiometric pH titrations indicate that the abundant proton transfer species present at pH < 4.5 is (creatH)+(pdtcH)-, in support of the single crystal X-ray structure. Ab initio method, DFT (B3LYP), was applied for achievement of the barrier energies of proton transfer processes and geometric parameters of transition states