Peroxidase-Catalyzed Synthesis of Polyphenols Bearing Aldehyde Units

摘要

It is already known that phenolic monomers bearing electron-withdrawing groups could hardly be polymerized by oxireductases. In this paper, enzymatic polymerization (EP) of phenolic monomers possessing electron-withdrawing aldehyde side-groups, protocatechualdehyde (PCA) and pyrogallolaldehyde (PGA), is presented. The monomers were converted to their polymers via enzyme-catalyzed oxidative polymerization in buffered-dioxane solution using horseradish peroxidase as the catalyst and hydrogen peroxide as the oxidant. The resulting products (abbreviated as PPCA and PPGA) were characterized by means of UVVis, FT-IR, ~(1)H-NMR, GPC (gel-permeation chromatography), TG–DTA and DSC analyses. IR and NMR data indicated that the obtained polymers consisted of a mixture of phenylene/oxyphenylene units, and the aldehyde (–CH=O) side-groups in the polymer chains were not oxidized. The electrical and electrochemical characterizations of the polymers were performed by solid-state conductivity and cyclic voltammetry (CV) techniques, respectively. Fluorescence analyses of PGA and PPGA were also conducted in DMSO. Emission maxima of PPGA were red shifted by nearly 34 nm compared to its monomer.