Purple subphthalocyanine-phthalocyanine dyad: Synthesis, photophysicochemical properties and DFT study

Abstract

A new phthalocyanine-subphthalocyanine heterodyad (5) was prepared by Pd(0)-catalyzed Sonogashira coupling reaction between an asymmetrical phthalocyanine (3) bearing monoiodo and multiple triazolide moieties on its backbone and a subphthalocyanine (4) bearing axially propargyl group. The structure of this heterodyad (5) was subsequently confirmed by the conventional spectroscopic techniques. The photophysical and photochemical properties including; fluorescence and singlet oxygen generation of (5) along with its building chromophores (3) and (4) were also investigated. Interestingly, a purple colored solution was observed by this novel dyad which was significantly different from those colors (green or blue) obtained by phthalocyanine-subphthalocyanine conjugates. Based on steady state absorption spectroscopic data and transient absorption results, the synthesized dyad5was free of aggregation and there is good energy transfer occurs between Pc and subPc moieties. This result was confirmed using density functional theory (DFT) and time-dependent DFT (TDDFT) analyses: B3LYP exchange-correlation functional and the 6-31 + G(d) basis set.