Self-assembly of a unique triangle-like tungstovanadate containing pentagonal {(WO 7 )W 3 (SnR) 2 } cluster.

In aqueous solution, a novel triangle-like tungstovanadate estertin derivative K 10 H 10.5 [(W 4 O 15 (H 2 O) 2 ){(SnCH 2 CH 2 COO) 2 (V 0.75 W 10.75 /V 0.25 O 39 )}{{(SnCH 2 CH 2 COO) 2 (μ-OH)} 2 (SnCH 2 CH 2 COO)(VW 10 O 37 )} 2 ]·31H 2 O ((SnR)8-V3W35, R = CH 2 CH 2 COO) was assembled by a conventional synthetic method. (SnR)8-V3W35 is composed of one [VW 11 O 39 ] 7- ({VW 11 }) and two [VW 10 O 37 ] 9- ({VW 10 }) units connected by eight [Sn(CH 2 ) 2 COO] 2+ groups and a {W 4 O 19 } cluster. Interestingly, there exists a pentagonal bipyramid WO 7 polyhedral center surrounded by two SnCO 5 and three WO 6 octahedra, forming a pentagonal {(WO 7 )W 3 (SnR) 2 } cluster in this polyoxometalate (POM), which is also the first example of a pentagonal structure formed by transition metals (TMs) and main group organometals in the POM family. Furthermore, the structure of this organic-inorganic hybrid POM also exhibits the largest number of organotin groups introduced into the POM system. It was characterized with various physico-chemical and spectroscopic methods, including X-ray single crystal and powder diffraction analysis, 119 Sn and 51 V NMR, IR, thermal gravimetric analysis (TGA), etc . In addition, the catalytic activity of (SnR)8-V3W35 as a mimic of peroxidase was evaluated using o -phenylenediamine (OPD) as a peroxidase substrate. The major factors influencing the oxidation reaction such as pH, the dosage of (SnR)8-V3W35, and concentrations of OPD and H 2 O 2 were mainly studied. (SnR)8-V3W35 exhibits good peroxidase-like catalytic activity. From another perspective, the successful acquisition of (SnR)8-V3W35 further proves the instability and easy reassembly characteristics of TM-sandwich-type tungstovanadates, which also provides a new assembly strategy for synthesizing POM-estertin derivatives.