Star-shaped Keggin-type heteropolytungstate nanostructure as a new catalyst for the preparation of quinoxaline derivatives

In this work, we report the novel successful preparation of the Keggin-type Cs(CTA)2PW12O40 (CTA = cetyltrimethylammonium cation) nanostructure by a microemulsion method. The microemulsion system included the cationic surfactant CTAB, 1-butanol as co-surfactant, isooctane as oil phase, and an aqueous solution containing CsNO3. The Cs(CTA)2PW12O40 nanostructure was formed by the addition of an aqueous solution of phosphotungstic acid to the microemulsion solution. Characterization of the resultant nanostructure was done using FT–IR spectroscopy, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, and CHN elemental analysis. The product was found to be a star-shaped nanostructure composed of some nanorods whose diameter and length are about 100 nm and 500 nm, respectively. The prepared nanostructure was used as a recoverable catalyst for the synthesis of quinoxaline derivatives by the condensation of 1,2-diamines with 1,2-dicarbonyl compounds, which afforded the products in good to high yields in short reaction times.