Three metal complexes derived from 3-methyl-1H-pyrazole-4-carboxylic acid: synthesis, crystal structures, luminescence and electrocatalytic properties

Mononuclear complexes [Cd(HMPCA)(2)(H2O)(4)] (1) and [Co(H(2)MPCA)(2)(DMF)(2)(H2O)(2)]Cl-2 (2), and 3D coordination polymer [Cd(3)C(l)2(HMPCA)(4)(H2O)(2)]center dot 2H(2)O (3) (H(2)MPCA = 3-methyl-1H-pyrazole-4-carboxylic acid) were synthesized and characterized by elemental analysis, IR spectra, thermogravimetric analysis, and X-ray single-crystal structure analysis. In 3, HMPCA(-) anions bridged trinuclear Cd(II) ions clusters to form an 8-connected 3D network with channels. The complexes all display green fluorescence in the solid state. As a bifunctional catalyst, complex 2 exhibited excellent catalytic activity for oxygen evolution reaction (OER), and certain catalytic activity for oxygen reduction reaction (ORR).