Synthesis and photophysical properties of a non-symmetrically substituted phthalocyanine-pyrene conjugate

An unsymmetrical zinc phthalocyanine (ZnPc) (5) bearing one pyrene (Py) and six tert-butylphenoxy units was synthesized in 3 steps. The unsymmetrical zinc phthalocyanine carrying the protecting group was synthesized in the first step. In the second stage, the protecting group was removed and in the final stage pyrene structure was introduced with the Sonagashira coupling reaction. The new compound was characterized by using spectroscopic techniques. The photophysical measurements of the conjugated structure were performed to determine the effect of the pyrene group on the fluorescence of Pc. It was determined that the absorption of the pyrene structure around 350 nm was overlapping with the B-band of phthalocyanine after conjugation. Fluorescence quantum yield (Φ_F) and lifetime (T_F) were calculated. The fluorescence quenching examinations were performed by adding the different concentration of 1,4-benzoquinone (BQ) in N,N-dimethylformamide (DMF) and the Stern-Volmer constant (K_sv) and quenching constant (k_q) values of unsymmetrical zinc phthalocyanine (5) were determined.