Carbon-centered dendritic radicals: photoinduced reaction of poly(benzyl ether) dendrons σ-bonded to a rhodium(III) porphyrin focal core

Poly(benzyl ether) dendrons σ-bonded by the focal dialkoxybenzyl unit to a rhodium(III) porphyrin functionality (1-Ln, n=1, 3–5) were synthesized as novel carbon-centered free radical equivalents. Upon excitation with visible light in a carbon monoxide atmosphere, 1-Ln (n=1, 3–5) underwent homolysis at the alkylrhodium bond to give the corresponding acylrhodium species 2-Ln (n=1, 3–5), where the consumption rate of 1-Ln was dependent on the generation number of the dendron unit. In particular, 1-L5 bearing the largest dendron unit was much reluctant to undergo photochemical reactions.