Novel azobenzene-phthalocyanine dyads—design of photo-modulated J-aggregation
Novel azobenzene-phthalocyanine dyads―― design of photo-modulated J-aggregation

Based on the J-aggregation mechanism of α-aryl/alkoxy-substituted zinc phthalocyanines(Pcs) in non-coordinating solvents, two novel azobenzene-phthalocyanine dyads (3-azo-ZnPc and 4-azo-ZnPc) were synthesized with the aim of developing Pc compounds whose ability to form J-aggregation could be photo-modulated. It was found that 3-azo-ZnPc in chloroform could be effectively photo-controlled in a wide range. This phenomenon could be explained by the changes in the geometry and dipole moment of azobenzene during the photo-isomerization process. 4-azo-ZnPc did not have this ability at all, with or without UV light illumination. The positions of the oxygen atoms to which the aryl/alkoxy substitution was attached relatively were found important in determining the aggregation ability. Supported by the National Natural Science Foundation of China (Grant Nos. 20572059, 20502013 and 20773077), National Key Fundamental Research Program (Grant No. 2007CB808000)