Two {CuI[P4Mo6]2}-Based Coordination Polymers Incorporating In Situ Converted Tetrapyridyl Ligands for Trace Analysis of Nitrofuran Antibiotics.

Nitrofurans are important synthetic broad-spectrum antibacterial drugs with the basic structure of 5-nitrofuran. Due to their toxicity, it is essential to develop a sensitive sensor with strong anti-interference capabilities for their detection. In this work, two {P4Mo6O31}12--based compounds, [H4(HPTTP)]2{CuI[Mo12O24(OH)6(PO4)3(HPO4)(H2PO4)4]}·xH2O (x = 13 for (1), 7 for (2); HPTTP = 4,4',4″,4‴-(1H-pyrrole-2,3,4,5-tetrayl)tetrapyridine), exhibiting similar coordination but distinct stacking modes. Both compounds were synthesized and used for the electrochemical detection of nitrofuran antibiotics. The tetrapyridine-based ligand was generated in situ during assembly, and its potential mechanism was discussed. Composite electrode materials, formed by mixing graphite powder with compounds 1-2 and physically grinding them, proved to be highly effective in the electrochemical trace detection of furazolidone (FZD) and furaltadone hydrochloride (FTD·HCl) under optimal conditions. Besides, the possible electrochemical detection mechanisms of two nitro-antibiotics were studied.

Improved capacitive performances and electrocatalytic reduction activity by regulating the bonding interaction between Zn-bistriazole-pyrazine/pyridine units and diverse Anderson-type polyoxometalates.

Electrochemical performances can be effectively improved by introducing metal-organic units (MOUs) into polyoxometalates (POMs). However, regulating the bonding strength between POMs and MOUs at the molecular level to improve the electrochemical performance is a challenging task. Three new POM-based metal-organic complexes (MOCs), namely H{Zn2(Hpytty)2(H2O)8[CrMo6(OH)6O18]}·2H2O (1), H{Zn2(Hpyttz)2(H2O)6[CrMo6(OH)6O18]}·8H2O (2), and {(µ2-OH)2Zn6(pyttz)2(H2O)10[TeMo6O24]}·2H2O (3) (H2pytty = 3-(pyrazin-2-yl)-5-(1H-1,2,4-triazol-3-yl)-1,2,4-triazolyl, H2pyttz = 3-(pyrid-2-yl)-5-(1H-1,2,4-triazol-3-yl)-1,2,4-triazolyl), were obtained. Single-crystal X-ray diffraction shows that the bonding strength (from the hydrogen bond to the coordination bond) between Zn-bistriazole-pyrazine/pyridine units and diverse Anderson-type POMs gradually increases from complexes 1 to 3. Glassy carbon electrodes modified with complex 3 (3-GCE) has the highest specific capacitance, which is 930 F g-1 at 1 A g-1. Moreover, carbon paste electrodes (1-3-CPEs) modified with complexes 1-3 are used as electrochemical sensors for detecting Cr(VI) ions, with limits of detection well below the World Health Organization (WHO) maximum level in drinking water.

Two new polyoxometalate-based metal-organic complexes for the detection of trace Cr(VI) and their capacitor performance.

Two new Keggin-type polyoxometalate (POM)-based metal-organic complexes (MOCs) H3[Cu2(4-dpye)2(PMo12O40)] (1) and H[Cu2(4-Hdpye)2(PMo12O40)(H2O)4]·2H2O (2) were constructed with a new N,N'-bis (4-pyrimidinecarboxamido)-1,2-ethane (4-H2dpye) ligand by the hydrothermal/solvothermal method. Complex 1 was a 2D layered structure constructed from 1D metal-organic chains [Cu(4-dpye)]n and Keggin-type [PMo12O40]3- polyoxoanions. Complex 2 displays a 3D supramolecular framework formed by discrete [PMo12O40]3- polyoxoanions and binuclear metal-organic loops [Cu2(4-Hdpye)2]. The electrocatalytic behaviors of carbon paste electrodes modified by complexes 1 and 2 (1-CPE and 2-CPE) were investigated. The 1-CPE and 2-CPE were used as electrochemical sensors to detect trace Cr(vi), and the low limits of detection (LOD) are 1.27 × 10-7 M for 1 and 1.71 × 10-7 M for 2, which are lower than the maximum allowable concentration of Cr(vi) in drinking water specified by the World Health Organization (WHO). In addition, the performances of complexes 1 and 2 modified carbon cloth electrodes (1-CC and 2-CC) as supercapacitor materials have also been studied. The influence of the structure on electrocatalytic and capacitor performances is discussed.

α-γ-Type [Mo8O26]4--Containing Metal-Organic Complex Possessing Efficient Catalytic Activity toward the Oxidation of Thioether Derivatives.

In this work, a new α-γ-type [Mo8O26]4- anion was first synthesized and characterized by single-crystal X-ray diffraction analysis and was obtained by introducing molybdate to the synthesis of metal-organic complex (MOC) under hydrothermal conditions. An octamolybdate-based MOC, namely, {[Cu8(H2O)6](dpyh)4(α-γ-Mo8O26) }·(ß-Mo8O26)·8.5H2O (H2dpyh = N,N-bis(3-pyrazolamide)-1,2-hexahydrobenzene), was obtained. The α-γ-type [Mo8O26]4- anion was composed of four MoO6 octahedra and four MoO5 trigonal bipyramids by sharing their edges and corners. The title complex exhibited a 1D structure in which an α-γ-type [Mo8O26]4- anion was connected with [Cu4(dpyh)2] units in a staggered manner. Under optimized conditions, complex 1 as the catalyst can achieve a highly efficient conversion (more than 99%) of thioanisole within 30 min and above 99% selectivity toward sulfoxide. Furthermore, efficient catalytic oxidation of thioether derivatives was also performed with 1 as the catalyst. In addition, the stable electrochemical sensing performance and adsorption capacity toward organic dyes were tested.