Synthesis of doubly strapped meso-meso-linked porphyrin arrays and triply linked conjugated porphyrin tapes

1,10-Dioxydecamethylene doubly strapped Zn^II-porphyrin S1 was prepared and treated with AgPF₆ to give meso-meso-linked porphyrin oligomers Sn (n = 2, 3, 4, 6, 8, and 12), which were converted to triply linked porphyrin tapes TSn by meso,meso′-dibromo meso-meso-linked porphyrin arrays BSn and meso,meso′-diphenyl meso-meso-linked porphyrin arrays PSn. The structures of S1 and S2 have been determined by single-crystal X-ray diffraction analysis. Characteristically, Sn exhibit sharp Q(0,0) absorption and fluorescence bands. Low energy Q-band-like absorption bands of TSn are progressively red-shifted with an increase in the number of porphyrins without saturation behavior of conjugation. The double straps suppress π-π stacking to some extent as seen from partial preservation of vibration structures in the Q-band-like bands of TS4 and TS6 and improve the chemical stabilities of longer tapes such as TS8 and TS12.