13C-NMR study of radical copolymers of (-)-menthyl methacrylate with trans-4-methacryloyloxyazobenzene
Abstract The 50.3 MHz 13 C-NMR of various free radical copolymers of (−)-menthyl methacrylate with trans -4-methacryloyloxyazobenzene was investigated in CDCl 3 solution at room temperature. The smooth variation of the chemical shifts of aromatic carbons with chemical composition points to a random distribution of the monomeric units along the polymer chain. Analysis of the carbonyl signal allows one to determine the main chain stereochemistry of copolymers in which one monomer predominates. Apart from the macromolecular nature, no appreciable effect on local mobility is observed arising from different neighbouring units and stereoregularity.
Aryl groups bound to the meso positions of porphyrins often react with neighboring groups, in particular s-acyl groups to give highly diversified monomeric and dimeric new functionalized porphyrins. The products, whose meso-aryl ring approaches coplanarity with the porphyrin macrocycle, show large shifts of UV-visible absorption bands and various potentialities for building external chelating moieties and assembling oligoporphyrins.