Free-base,copper (II) and zinc (II) derivatives of an azomethine bridged 'porphyrin-pyrene' dyad:Synthesis,spectroscopy and photochemistry

摘要

Free-base,copper (II) and zinc (II) derivatives of a porphyrin-pyrene conjugate having an azomethine group separating the two photoactive subunits have been synthesized and fully characterized by mass (FAB),IR,UV/visible,~1H NMR and ESR spectroscopies and also by the cyclic-and differential pulse voltammetric methods.An analysis of the data reveals that the spectral and electrochemical properties of the individual chromophoric entities are retained and that there exists no specific pi-pi interaction between the porphyrin and pyrene subunitsi n these dyads.Excitation of CH_2Cl_2 solutions of the free-based and zinc (II) derivatives at 550 nm results in no quenching of fluorescence due to the tetrapyrrolic moiety,but that at 290 nm results in a quenching of fluorescence due to the appended pyrene moiety.Excitation spectral data indicates that photons collected by the hydrocarbon subunit are effectively transferred to the porphyrin in both these donor-acceptor systems.