Epoxidation of Alkenes on Soft Oxometalate (SOM) based Trails Patterned by using Laser of Optical Tweezers set up

Preethi Thomas, Subhrokoli Ghosh and Prof. Dr. Soumyajit Roy

We have developed a novel method of patterning ammonium heptamolybdate tetrahydrate based trails or arrays on a glass substrate using the laser beam of thermo-optical tweezers set up and use them for site specific catalysis. The trail of heptamolybdate primarily comprise of its polyoxometalate (POM) crystalline state formed from the phase transition of its dispersion phase soft oxometalate (SOM) upon exposure to laser beam of 1064 nm wavelength of thermo-optical tweezers set up. The supramolecular self-assembly of the SOMs facilitates their nucleation to POMs upon laser irradiation. The SOMs and SOM based trails have been characterized using various techniques such as FTIR spectroscopy, Raman spectroscopy, Thermogravimetric analysis and Atomic Force microscopy. These trails or arrays have been subsequently employed as catalytic avenues for site-specific catalysis of epoxidation of alkenes namely styrene, 1-octadecene, cis-cyclooctene and cyclohexene and studied using time resolved Raman spectroscopy. Site specificity here signifies the confinement of catalysis in a particular zone which in this work is the region where galleries of heptamolybdate have been etched on the glass slide.

DOI