Synthesis and Characterization of a Crown-Shaped 36-Molybdate Cluster and Application in Catalyzing Knoevenagel Condensation

Abstract

A novel crown-shaped 36-molybdate cluster with organophosphonate-functionalized polyoxomolybdates, (NH4)17Na7H12[Co­(H2O)­TeMo6O21{N­(CH2PO3)3}]6·42H2O, has been successfully synthesized and well-characterized. It owns the highest nuclearity in the family of organophosphonate-based polyoxometalates reported so far. Furthermore, for the first time in the field, we illustrated that polyoxomolybdate could work as an effective heterogeneous catalyst for the Knoevenagel condensation reaction with high TOF (7714 h–1) and good recyclability. Impressively, the catalytic performance of 1 was also tested successfully in a large scale (∼10 g) reaction, where 89% of reaction yield and 3216 of TON were afforded.

V═O Functionalized {Tm2}–Organic Framework Designed by Postsynthesis Modification for Catalytic Chemical Fixation of CO2 and Oxidation of Mustard Gas

“…In view of these remarkable characteristics of NUC-11 , including a high proportion of void volume, a large specific surface area, abundant active metal sites (VO and Tm III ), and moderate CO 2 adsorption capacity, the catalytic activity of NUC-11 was explored for the cycloaddition reaction of epoxides with CO 2 , widely regarded as a two-step catalytic reaction. − To explore the influence the of reaction conditions on the conversion rate of epoxide, propylene oxide was selected as a model substrate and the desired product of propylene carbonate was determined by 1 H NMR (Figure S12). In a typical experiment, the amount of propylene oxide was fixed at 20 mmol, exhibiting a low conversion rate of 9% in the presence of only activated NUC-11 at 50 °C (entry 2, Table ); meanwhile a similarly low conversion rate of 17% was observed in the presence of only the cocatalyst Bu 4 NBr (entry 3).…”

Assembly of a Hexameric Cluster of Polyoxomolybdotriphosphonate Builts from [Zn(H2O){TeMo6O21}{N(CH2PO3)3}]6– Subunits and Its Optical and Catalytic Properties

“…51,52 In 2020, our group isolated two novel ATMPmodified POMs. 53,54 By a summary of the previously reported ATMP-embedded POMs, it can be easily found that ATMP is more flexible in its spatial morphology, which increases the expectation that it benefits the construction of POM building blocks. In addition, ATMP as the organic ligand is nontoxic.…”

“…At the same year, our laboratory also synthesized a 24-molybdenum-membered polyanion of an ATMP-supported tetramer, [{N­(CH 2 PO 3 ) 3 }­Mo 6 O 16 (OH)­(H 2 O) 4 ] 4 12– . What is more, our group also reported the series of S-shaped organotriphosphonate polyoxotungstates [H 4 {(AsW 9 O 33 )­TM­(H 2 O)­W 5 O 11 (N­(CH 2 PO 3 ) 3 )} 2 (μ 2 -O) 2 ] 10– (TM = Zn, Ni, Co, Mn). , In 2020, our group isolated two novel ATMP-modified POMs. , By a summary of the previously reported ATMP-embedded POMs, it can be easily found that ATMP is more flexible in its spatial morphology, which increases the expectation that it benefits the construction of POM building blocks. In addition, ATMP as the organic ligand is nontoxic .…”

A Copper-Containing Polyoxometalate-Based Metal–Organic Framework as an Efficient Catalyst for Selective Catalytic Oxidation of Alkylbenzenes

“…Polyoxometalates (POMs), as a class of nanosized discrete anionic metal-oxide clusters, have drawn enormous attention and are applied widely in many fields (e.g., magnetism, medicine, electrochemistry, and especially in catalysis) because of their unique physicochemical properties. − In recent years, many researchers have demonstrated POM-based catalysts did have praiseworthy catalytic performance for selective oxidation of DPM to BP. − However, POMs suffer from some intrinsic drawbacks, including low specific surface area, high water solubility, and difficult separation (reuse), which shackle the further industrial applications of POMs. ,,− Therefore, a promising solution is to select a proper carrier and load the POMs . Simultaneously, metal–organic frameworks (MOFs), which have tunable nanospaces providing satisfactory accommodation for multitudinous guest species, have been regarded as a new class of porous materials. − Thanks to their inherent tunability, MOFs have cumulative application in gas storage, magnetism, fluorescence, and catalysis.…”