Functional Coordination Polymers from a Bifunctional Ligand: A Quantitative Transmetalation via Single Crystal to Single Crystal Transformation

Abstract

Three new coordination polymers (CPs) have been synthesized by employing a bifunctional ligand, formulated as {Zn(bppCOO) 2 } n (1), {Cu(bppCOO) 2 } n (2), and {Co(bppCOO)(HCOO)(H 2 O)} n ·n1.5H 2 O (3) (where bppCOOH = 2,6-bis(pyrazol-1-yl)pyridine-4-carboxylic acid). Compounds 1 and 3 are obtained under hydrothermal conditions, whereas compound 2 is achieved when compound {Zn(bppCOO) 2 } n (1) undergoes a direct metal exchange process with Cu(II)-salt in a quantitative single crystal to single crystal transformation process (solid-liquid interface reaction), retaining its structural integrity. Thus, compounds 1 and 2 are structurally isomorphous. The deprotonated form of bppCOOH ligand links adjacent metal centers by utilizing both carboxylate and tridentate N donors to form one-dimensional coordination polymers. All the compounds 1-3, are well characterized by powder X-ray diffraction, IR spectroscopy, CHNS, and thermogravimetric analyses. Finally, all three compounds are characterized unambiguously by single crystal X-ray diffraction analysis. We have demonstrated that the compound {Co(bppCOO)(HCOO)(H 2 O)} n ·n1.5H 2 O (3) having Co(II) coordinated water has potential in exhibiting electrocatalytic water oxidation at a neutral pH.