Effect of substituent patterns on the aggregation and photophysical properties of novel C2-symmetric diol-based peripherally and non-peripherally zinc phthalocyanines

Abstract

Two zinc(II) phthalocyanines (4 and 6) and two cobalt(II) phthalocyanines (5 and 7) with four (1R,2R)-1,2-bis(3ʹ-phenylphenyl)ethane-1,2-diol at peripheral and non-peripheral positions of the phthalocyanine ring have been synthesized starting from (1R,2R)-1,2-bis(3ʹ-phenylphenyl)ethane-1,2-diol substituted chiral phthalonitriles 2 and 3, respectively. The aggregation properties of newly synthesized phthalocyanines 4–7 were examined in coordinating and non-coordinating solvents by UV–Vis spectroscopy. Their photophysical parameters including fluorescence quantum yields and lifetimes were determined in dichloromethane. Peripherally and non-peripherally (1R,2R)-1,2-bis(3ʹ-phenylphenyl)ethane-1,2-diol substituted zinc(II) phthalocyanines 4 and 6 showed the formation of J-type aggregation in non-coordinating solvents, respectively. A series of UV–Vis experiments were designed to understand the factors affecting the nature of aggregation. These experiments revealed that the J-aggregates are formed by coordination of oxygen atoms to Zn(II) ion in the center of phthalocyanines in non-coordinating solvents. All newly synthesized compounds are characterized by FT-IR, NMR, UV–Vis, Circular Dichroism (CD) and MALDI-TOF MS spectral data.