RESUMEN

A novel, easily prepared and accessible water-soluble supramolecular catalyst for the Suzuki-Miyaura CC coupling reaction was synthesized and characterized by FTIR, NMR, XRD, SEM, and HR-TEM. An inexpensive Pd(II) source added to the resulting aqueous solution of thioglycolic ester ß-cyclodextrin (1-TGA-SH-ß-CD/PdCl2) showed Pd nanoclusters and efficient catalytic activity for Suzuki-Miyaura CC coupling reactions of aryl halides with aryl boronic acids, employing K2CO3 as base, in an environmentally benign aqueous solution prepared in open flasks. Organic aryl halides including chlorides can produce moderate to excellent yields with aryl boronic acids and a small catalytic amount (0.01 mol%) of 1-TGA-SH-ß-CD/PdCl2. This hydro-soluble catalyst stock solution was stable for long periods (more than three months) and could be reused in two runs until showing loss of catalytic activity. Some experiments to understand the mechanism were performed, with the results suggesting incorporation of aryl halide in the catalytic cavity.

Asunto(s)

Agua , beta-Ciclodextrinas , Agua/química , Ésteres , Catálisis , Ácidos Borónicos/química

RESUMEN

Crosslinking and functionalizing agents play crucial roles in the properties/applications of cyclodextrin polymers. Here we report the synthesis of water-insoluble cyclodextrin polymers containing l-glutamic acid. In a first route, ß-cyclodextrin was crosslinked with citric acid and subsequently functionalized with l-glutamic acid, while a second route involved esterification of ß-cyclodextrin with l-glutamic acid, catalyzed by tin octoate. Combined evaluation by FTIR, 13C CP/MAS NMR and elemental analysis indicated that the sample from the first route had the largest fraction of glutamic acid. Sorption tests with methyl orange showed that the cyclodextrin cavities were slightly more available in the polymer obtained through the second route. Samples were employed as reductant and stabilizer for fast and easy synthesis of silver nanoparticles at room temperature. Brief UV irradiation was sufficient for samples produced by the first route.