Preparation, characterizaton, and catalytic aerobic oxidation by a vanadium phosphonate mesoporous material constructed from a dendritic tetraphosphonate

The synthesis of a new vanadium phosphonate material (TPPhA-V), prepared by the non-hydrolytic condensation of a vanadium(V) alkoxide with an arylphosphonic acid, is presented. Transmission electron microscopy (TEM) of TPPhA-V showed the specimen to be granular with small highly contrasting dots situated within the a more poorly contrasting substance, while the scanning electron microscopy (SEM) examination revealed formation of spongelike amorphous material as the only type of the specimen morphology. Room-temperature electron spin resonance measurement of the TPPhA-V isotropic broad singlet resonance line indicated strong interaction between neighboring vanadium (IV) atoms. The test of the catalytic properties of TPPhA-V showed that the oxidation generally proceeded smoothly with the formation of corresponding benzylic aldehydes at high conversion and selectivity.