Assembly of polyoxometalate-thiacalix[4]arene-based inorganic-organic hybrids as efficient catalytic oxidation desulfurization catalysts

Thiacalix[4]arene-protected alkynyl Agn (n = 9, 18) nanoclusters: syntheses, structural characterizations, photocurrent responses and fluorescence properties

Two thiacalix[4]arene-protected silver(I) alkynyl nanoclusters, [Na2(H2O)2][Ag9(TC4A)(tBuCC)4(CH3OH)2(SbF6)0.5(OH)2.5]·3.5H2O·CH3OH (1, abbreviated as Ag9) and [Ag9(TC4A)(tBuCC)4(CF3COO)]2·4CH3OH (2, abbreviated as Ag18), were synthesized by the reaction of [tBuCCAg]n, p-tert-butylthiacalix[4]arene (H4TC4A), NaBH4, and AgSbF6 or CF3COOAg in the mixed solvent of methanol-trichloromethane-toluene under solvothermal conditions, respectively. Driven by SbF6- and CF3COO- with different coordination properties, the structural unit [Ag9(TC4A)(tBuCC)4]+ in both the compounds migrated in different modes, accompanied by distinct Ag⋯Ag distances. Ag9 and Ag18 exhibit similar UV-Vis absorption and diffuse reflection spectra along with contrary tendency between photocurrent responses and solid-state fluorescence. The solution stability of Ag9 and Ag18 was demonstrated by 1H NMR and MALDI-TOF mass spectrometry. The fluorescence responses of Ag9 and Ag18 towards different organic molecules were also investigated, which indicated that the polarity of solvent has a certain effect on the emission intensities of Ag9 and Ag18. This study provides a positive guide for the controlled synthesis and further study of the structure-activity relationship of thiacalix[4]arene-protected silver alkynyl nanoclusters.

Thiacalix[4]arene-based complex with Co(II) ions as electrode modifier for simultaneous electrochemical determination of Cd(II), Pb(II), and Cu(II)

A complex [Co₄(TCTA)₂(H₂O)₈]∙10H₂O (Co-TCTA) based on thiacalix[4]arene derivative has been synthesized for the first time using the solvothermal method. The glassy carbon electrode (GCE) modified with Co-TCTA (Co-TCTA/GCE) could simultaneously determine Cd²⁺, Pb²⁺, and Cu²⁺ at around - 0.75 V, - 0.60 V, and - 0.10 V (vs. ref. Ag/AgCl) and had good stability, selectivity, and reproducibility with relative standard deviation (RSD) of 4.4% for Cd²⁺, 1.4% for Pb²⁺, and 5.4% for Cu²⁺. Co-TCTA/GCE showed wide linear range of 0.4-8.0 μM for Cd²⁺, 0.4-7.0 μM for Pb²⁺, and 0.6-6.0 μM for Cu²⁺ when three ions were determined simultaneously. The limits of detection (LODs) of Cd²⁺, Pb²⁺, and Cu²⁺ were 0.071 μM, 0.022 μM, and 0.021 μM, respectively. Moreover, the sensor was used to determine three ions in lake water sample with satisfactory recoveries of 93.6-93.8% for Cd²⁺, 93.8-103.3% for Pb²⁺ and 94.6-95.3% for Cu²⁺. The good adsorption capacity of Co-TCTA and Co(II)/Co(0) circular mechanism on the surface of the electrode were proposed to enhance the electrochemical signals. This work enriched the theoretical research on the complexes for the determination of heavy metal ions.

Two Cu(i)-based inorganic–organic complexes assembled with polyoxometalate and thiacalix[4]arene for efficient catalytic reactions

Two Cu(i)-based inorganic–organic complexes were synthesized, which can be used as high-efficiency heterogeneous catalysts for ODS and AAC reactions, respectively.

Two POM-based compounds containing Zn-capped Keggin anions as decent heterogeneous catalysts for sulfur oxidation and cycloaddition of CO2 reactions

Carbon dioxide (CO2) and the combustion of sulfide in gasoline are the main causes of air pollution. Great deal of attention has been committed to solving the problem and the...