Cyclodextrins in Polymer Synthesis: Enzymatic Polymerization of a 2,6‐Dimethyl‐β‐Cyclodextrin/2,4‐Dihydroxyphenyl‐4′‐Hydroxybenzylketone Host‐Guest Complex Catalyzed by Horseradish Peroxidase (HRP)

Abstract This paper reports the enzymatic polymerization of the inclusion complex 2,4‐dihydroxyphenyl‐4′‐hydroxybenzylketone/2,6‐dimethyl‐ β ‐cyclodextrin by horseradish peroxidase (HRP) in aqueous media. The structure of the complex was determined by means of NOESY‐NMR and crystallographic analysis (indicating an orthorhombic structure). The enzymatic polymerization of the uncomplexed 2,4‐dihydroxyphenyl‐4′‐hydroxybenzylketone yields oligomers with molecular weights up to $\overline M _{\rm w} = 4 \times 10^3$ in organic‐aqueous media, but because of its poor solubility in aqueous systems, no polymerization is observed if water is used as solvent. An increase of the availability of the ketone in solution is achieved by complexing it with random‐methylated β ‐cyclodextrin in water. We found that the use of methylated β ‐cyclodextrin in equimolar concentration to the monomer increases the polymerization yield and the average molecular weight. The polymers formed were analyzed by GPC and ATR‐FTIR techniques. Representation from X‐ray diffraction analysis of the 2,6‐dimethyl‐ β ‐cyclodextrin/2,4‐dihydroxyphenyl‐4′‐hydroxybenzylketone host‐guest complex ( 3 ). magnified image Representation from X‐ray diffraction analysis of the 2,6‐dimethyl‐ β ‐cyclodextrin/2,4‐dihydroxyphenyl‐4′‐hydroxybenzylketone host‐guest complex ( 3 ).