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

Three new Anderson-type polyoxometalate (POM)-based metal–organic frameworks (POMOFs) [Co 3 (L 1 )(TeMo 6 O 24 )(H 2 O) 10 ]·8H 2 O ( 1 ), [Co 3 (L 2 )(TeMo 6 O 24 )(H 2 O) 10 ]·8H 2 O ( 2 ) and [Cu 3 (L 1 )(TeMo 6 O 24 )(H 2 O) 10 ]·6H 2 O ( 3 ) (L 1 ​= ​N,N′-bis(4-pyrimidinecarboxamido)-1,2-ethane, L 2 ​= ​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 [TeMo 6 O 24 ] 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. Three new 3D POMOFs with fascinating structures based on [TeMo 6 O 24 ] 6– anions were synthesized, which exhibit the bifunctional electrocatalytic activities and the ability to selectively detect heavy metal ion Cr(VI). In addition, POMOFs 1 – 3 can quickly adsorb organic dye gentian violet. • Three new POM-based metal-organic frameworks (POMOFs) were obtained under 90 ​°C aqueous solution for two days. • POMOFs 1 – 3 represent the first examples of 3D POMOFs derived from bis(pyrimidine)-bis(amide) ligands and POMs. • POMOFs 1 – 3 exhibit excellent electrochemical sensing behaviors toward Cr(VI) ions. • POMOFs 1 – 3 can quickly adsorb the cationic dye Gentian Violet (GV) under dark conditions.