Optical and electrochemical properties of peripherally substituted chromium and manganese phthalocyanines

New chromium phthalocyanine complex peripherally substituted with 8-quinolinoxy group was synthesized from modified precursor 4-(8-quinolinoxy) phthalonitrile in presence of CrCl3·6H2O in DMAE, using zinc dust as the reducing agent. The emission spectrum of Cr(III)QPc-O-Cr(III)QPc also exhibited a reciprocal relationship in the intensity of the dual peaks when the excitation wavelength was varied from 350 to 440 nm. The spectrum also revealed a unique peak at 510 nm, mostly due to the combined effect of radiative relaxation of second excited singlet state to ground state (S2→S0) and the LMCT of Pc2- to Cr(III) metal center. The preparation of unstable manganese phthalocyanine, MnQPc, had been rarely reported owing to its aerobic oxidation to the more stable and often synthesized analogue, MnQPc(CH3COO). In this report, the synthesis of MnQPc was achieved under normal cyclization conditions and the effect of acetic acid and chlorinated solvents on the oxidative stability of MnQPc was studied.