Synthesis of covalently linked linear porphyrin triad and tetrad containing different porphyrin sub-units

Covalently linked diarylethyne bridged unsymmetrical porphyrin triad containing ZnN4, N4, and N2S2 porphyrin sub-units and porphyrin tetrad containing ZnN4, N4, N3S, and N2S2 porphyrin sub-units were synthesized over sequence of Pd(0) mediated coupling reactions. The triad and tetrad are freely soluble in all common organic solvents and characterized by ES-MS, NMR, absorption, fluorescence, and electrochemical techniques. The 1H NMR, absorption, and electrochemical studies indicated a weak interaction between the porphyrin sub-units of porphyrin triad and porphyrin tetrad. The steady state and time-resolved fluorescence studies supported an energy transfer from one end of porphyrin array to the other end. This kind of porphyrin arrays containing different porphyrin sub-units will be useful for molecular electronics applications.