Polyoxometalates in Catalytic Photochemical Hydrocarbon Functionalization and Photomicrolithography

Abstract

The energetic and mechanistic features of catalytic photochemical oxidation of organic substrates by polyoxometalates and then the applications of this chemistry to catalytic alkane functionalization, microlithography, and catalytic dehalogenation are succinctly reviewed Three sets of experiments that affect these areas are presented, and the future development of catalytic photoredox processes effected by polyoxometalates is discussed The excited state of decatungstate, W_(10)O_(32)^(4-) (1), and the conventional ground-state radical, tert-BuO·, have similar reactivities and lead to similar products upon reaction with various organic substrates. The simultaneous photooxidation of cyclooctane and tetrahydrofuran leads to some cross-coupling product and a complex organic product distribution that is consistent to a large degree with intermediate freely diffusing radicals. Laser flash photolysis measurements (355-nm frequency tripled Nd:YAG output of the heretofore unreported emission of 1 (λ_(max) = 615 nm) establish that the lifetime of the excited state (1^*) is 21 ± 3 ps at 25 °C in 9:1 acetonitrile—water solution.

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