Hydrothermal Synthesis, Crystal Structure and Electrochemical Property of Two Inorganic–Organic Hybrid Frameworks via Hydrogen Bonding

Two inorganic–organic hybrid frameworks, namely [Cu2(pdca)2(bibp)(H2O)2]·H2O (1) and [Fe(pdca)(pyco)(H2O)]·H2O (2) (H2pdca = pyridine-2,6-dicarboxylic acid, bibp = 4,4′-bisimidazolylbiphenyl, pyco = picolinate N-oxide) were synthesized via hydrothermal reactions. Both compounds have been characterized by elemental analysis, spectroscopic analysis, thermogravimetric analysis (TGA) and the single crystal diffraction. Complex 1 is dinuclear and five-coordinated copper(II) complex, while complex 2 displays mono-nuclear and six-coordinated iron(III) complex. In the crystal structures of both complexes, the coordinated and crystalline water molecules and H2pdca ligands contribute to the formation of O–H···O and C–H···O hydrogen bonds, which link the molecules into layers parallel. Cyclic voltammetry (CV) analysis shows one reversible reduction potential at 0.14 V (Epc) in complex 1, whereas in complex 2 shows a reduction potential at 0.15 V (Epc) in the cathodic region.