Three Anderson-type POMOFs with bis(pyrimidine)-bis(amide) ligands: Synthesis, fascinating structures and performances of electrochemical sensing and dye adsorption

Abstract

Three new Anderson-type polyoxometalate (POM)-based metal–organic frameworks (POMOFs) [Co3(L1)(TeMo6O24)(H2O)10]·8H2O (1), [Co3(L2)(TeMo6O24)(H2O)10]·8H2O (2) and [Cu3(L1)(TeMo6O24)(H2O)10]·6H2O (3) (L1 ​= ​N,N′-bis(4-pyrimidinecarboxamido)-1,2-ethane, L2 ​= ​N,N′-bis(4-pyrimidinecarboxamido)-1,4-butane) were obtained under 90 ​°C aqueous solution for two days. POMOFs 1–3 show fascinating 3D framework structures formed by transition metal linking bis(pyrimidine)-bis(amide) ligands and Anderson-type [TeMo6O24]6– anions. The carbon paste electrodes bulk-modified by POMOFs 1–3 (1-, 2-, 3-CPEs) have good bifunctional electrocatalytic performance towards the oxidation of ascorbic acid and the reduction of potassium bromate, potassium nitrite and heavy metal ions Cr(VI). 1-, 2-, 3-CPEs can be used as electrochemical sensors for the detection of Cr(VI), the limits of detection (LODs) are 0.389 ∼ 0.422 ​μM, which are lower than the 1.0 ​μM standard set by the WHO. In addition, the adsorption properties of POMOFs 1–3 on organic dyes gentian violet (GV) and methyl orange (MO) were investigated.