Synthesis, characterization and catalytic application of a new organometallic oligomer based on polyhedral oligomeric silsesquioxane

Abstract

Although homogeneous catalysts provide high performance and selectivity, the difficulty of separation and recycling of these catalysts has bothered the scientific community worldwide. Therefore, the demand for heterogeneous catalysts that possess the advantages of homogeneous ones, with ease of separation and recyclability remains a topic of major impact. The oligomeric catalyst synthesized in this work was characterized using elemental analysis, Fourier transform infrared, 13 C NMR, 29 Si NMR and energy-dispersive X-ray spectroscopies, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy and Brunauer-Emmett-Teller analysis and compared to its homogeneous counterpart [W(CO) 3 Br 2 (ATC)] in the epoxidation of 1-octene, cyclooctene, (S)-limonene, cis-3-hexen-1-ol, trans-3hexen-1-ol and styrene. The results showed that the percentage conversion for the homogeneous species [W(CO) 3 Br 2 (ATC)] was slightly higher than for the oligomeric catalyst (POSS-ATC-[W(CO) 3 Br 2 ]). Furthermore, the selectivity for epoxide of the oligomeric catalyst was greater than that of the homogeneous catalyst by about 25% when (S)-limonene was used. Great conversions (yields) of products were obtained with a wide range of substrates and the catalyst was recycled many times without any substantial loss of its catalytic activity.

An engineered POSS drug delivery system for copper(ii) anticancer metallodrugs in a selective application toward melanoma cells

“…The intense band at about 1100 cm −1 is typical of siloxane groups (Si-O-Si) present in each compound and in the precursor material (POSS-Cl). 49,50 Additionally, the bands for νC-H nearby 2957 and 2877 cm −1 are due to the propyl chain of the precursor POSS-Cl, as shown in Fig. S4A.…”

POSS nanostructures in catalysis

“…In another study, the same authors supported [W(CO)3Br2(NCMe)2] complex on the same POSS units used for the synthesis of catalysts 17 and 18. 56 The obtained tungsten hybrids (W-POSS)…”

Synthesis of two new Mo(II) organometallic catalysts immobilized on POSS for application in olefin oxidation reactions

“…The reaction mixture was allowed to stir for six weeks. The resultant solution was then filtered and dried to give a white solid (POSS-PrCl) with 41% yield, according to our previous work [4]. Elemental Analysis for Si 8 O 12 C 24 H 48 Cl 8 (1036.9 g/mol): calculated C 27.77%, H 4.63%; found C 27.56%, H 4.42%.…”

“…Ethanol was added to precipitate octa[3-amino-1,2,4-triazole-5-carboxylic acid) propyl] silsesquioxane. The precipitate was separated by filtration and washed with ethanol resulting in the POSS-ATZAc, according to our previous work [4]. The resulting product was obtained after several attempts.…”

“…The organometallic complex [Mo(CO) 3 Br 2 (NCMe) 2 ] was prepared according to literature methods [1,4,5]. A solution of Mo-II (2.3 g, 5.45 mmol) in ethanol (60 mL) was treated with 3-amino-1,2,4-triazole-5-carboxylic acid (ATZAc) (0.70 g, 5.45 mmol).…”