Singlet oxygen generation using PDMS occluded dyes

Several dyes that generate singlet molecular oxygen (O-1(2)) were occluded in polydimethylsiloxane (PDMS). For the homogeneous dyes, this occlusion forms an easy way of heterogenization, whereas it improves the performance of dyes that are heterogenized already in molecular sieves. These systems were investigated for the singlet oxygenation of test substrates, such as 2,3-dimethyl-2-butene and 1-methyl-1-cyclohexene. The PDMS elastomer was selected for its transparent, hydrophobic and permeability characteristics. The elastomer is 'wrapped' around the sensitizing system and hence shields the dyes from polar components, such as water, and balances the sorption of solvents and reagents. This results in an enhanced oxygenate yield for water sensitive dyes. Finally, a new porphyrin, 5,15-(2,6-dichlorophenyl)-10,20-(4-allyloxyphenyl)porphyrin, was synthesized and chemically anchored to PDMS, resulting in a highly active heterogeneous singlet oxygen generating system. (C) 2001 Elsevier Science B.V. All rights reserved.