The design and synthesis of a bifunctional catalyst to tackle environmental pollution caused by 2-chloroethyl ethyl sulfide (CEES) and phenolic compounds is meaningful. In this study, a new three-dimensional (3D) polyoxovanadate (POV)-based metal–organic framework, [Co(L)(V₄O₁₂)_0.5(H₂O)]·2H₂O (1; L = N,N’-bis(3-methylpyridin-3-yl)-2,6-naphthalenediamide), was synthesized under hydrothermal conditions. 1 was characterized using single-crystal X-ray diffraction analysis, infrared spectroscopy, and powder X-ray diffraction. Structural analysis shows that the [V₄O₁₂]^4– clusters and pairs of Co²⁺ cations are alternately connected to form a one-dimensional inorganic chain, eventually generating a 3D (4,4)-connected framework through the expansion of L, which exhibits a two fold interpenetration array. As a bifunctional catalyst, 1 exhibits satisfactory catalytic properties for the selective oxidation of 2-chloroethyl ethyl sulfide to the corresponding sulfoxide, with an effective conversion of > 99% and selectivity of 97%. Furthermore, 1 exhibits excellent photocatalytic degradation activity toward phenol, 2-chlorophenol, and m-cresol under visible light. The degradation efficiencies were above 92.6% for 140 min. The photocatalytic reaction kinetics, mechanisms of photodegradation, and recycling capability of phenol were also investigated in detail.

Under hydrothermal conditions, a Keggin-type polyoxometalate-based metal–organic complex, H₄{[Cu₄(EDDP)₂(H₂O)₅]_1.5(SiW₁₂O₄₀)}∙7.5H₂O (CuW-EDDP, H₄EDDP = ethylene-diamine-N,N'-dipropionic acid), was synthesized by reacting Na₁₀[A-α-SiW₉O₃₄]·18H₂O and CuCl₂·2H₂O in the presence of H₄EDDP ligands and characterized by powder and single-crystal X-ray diffraction, infrared spectroscopy, elemental analysis, and thermogravimetry. Interestingly, CuW-EDDP exhibited a three-dimensional structure with (4,6)-connected constructed from [SiW₁₂O₄₀]⁴⁻ units and tetranuclear Cu complexes [Cu₄(EDDP)₂(H₂O)₅]. As an effective heterogeneous catalyst, CuW-EDDP exhibited excellent performance, good reusability, and structural stability in the selective oxidation of methyl phenyl sulfide with high conversion (100%) and selectivity (98%) within 30 min. Furthermore, the catalytic activity of CuW-EDDP in the oxidation of other sulfide derivatives was investigated.

By introducing a new “V”-like semirigid bis-imidazole-bis-amide ligand, 4,4’-bis(1H-imidazole-4-carboxamide)phenylmethane (L), into a reaction system containing Anderson-type polyoxoanions, three polyoxometalate-based metal–organic complexes (POMOCs) with different metal ions were successfully synthesized under solvothermal conditions. The as-prepared POMOCs [Zn₂L₂(H₂O)₄][Zn(H₂O)₂(TeMo₆O₂₄)]·9H₂O (1), [Ni(H₂O)₆][Ni₂L₂(H₂O)₂[AlMo₆(OH)₆O₁₈]₂]·9H₂O (2), and [Co(H₂O)₆][Co₂L₂(H₂O)₂[AlMo₆(OH)₆O₁₈]₂]·11.5H₂O (3) show sandwich-like supramolecular structures. Complexes 2 and 3 are isostructural, having two [ML(H₂O)₂]²⁺ chains with [AlMo₆(OH)₆O₁₈]³⁻ polyoxoanions as pendants arranged in an interdigital mode to construct the sandwich-like architecture, whereas in complex 1 the anionic [Zn(H₂O)₂(TeMo₆O₂₄)]⁴⁻ chain is sandwiched by two cationic [ZnL(H₂O)₂]²⁺ chains to generate the supramolecular structure. POMOCs 1–3 display excellent electrochemical sensing behavior for Cr(VI), Fe(III), BrO₃⁻, and NO₂⁻ ions and efficient catalytic performance in sulfide oxidation. The effect of the central metal on the electrochemical sensing and sulfide oxidation performance and that of the special architecture of 1 on the detection ability are discussed.