Synthesis and properties of covalently linked BF2–oxasmaragdyrin–porphyrin dyads and triad

Two covalently linked diphenyl ethyne bridged unsymmetrical dyads containing porphyrin and BF2–oxasmaragdyrin and Zn(II)porphyrin and BF2–oxasmaragdyrin units and one covalently linked triad containing Zn(II)porphyrin, porphyrin and BF2–oxasmaragdyrin units were synthesized by coupling appropriate functionalized macrocycles under Pd(0) coupling reaction conditions. The dyads and triad were freely soluble in common organic solvents and confirmed by ES-MS spectra. 1D and 2D NMR techniques were used to characterize the dyads and triad. Absorption and electrochemical studies of dyads and triad showed the overlapping features of the constituted macrocycles indicating that the macrocycles retain their basic features in the dyads and triad. The BF2–oxasmaragdyrin absorbs at lower energy and emits strongly in the visible region compared to porphyrin/Zn(II)porphyrin. Thus, BF2–oxasmaragdyrin acts as energy acceptor and porphyrin/Zn(II) porphyrin act as energy donor in dyads and triad. The steady state and time-resolved fluorescence studies supported an efficient energy transfer from porphyrin/Zn(II)porphyrin to BF2–oxasmaragdyrin unit in dyads and triad.