New hybrid porphyrin tapes comprising meso-3,5-di-tert-butylphenyl-substituted Zn(II) -porphyrins (D) and meso-pentafluorophenyl-substituted Zn(II) -porphyrins (A) were synthesized via cross-condensation of meso-formyl porphyrins 1, 5, and 9 with oligopyrromethanes 2 and 6 as key steps. These hybrid tapes exhibit improved solubilities and enhanced chemical stability as compared with original Dn porphyrin tapes, and all display remarkably coplanar structures favorable for π-conjugation. The absorption spectrum of ADDA displays Q-like bands at 1400 and 1657 nm with a vibronic structure characteristic of porphyrinoids. The cyclic voltammograms exhibited positively shifted oxidation and reduction waves in the order of DDD<DAD<ADA<AAA. Tetrameric tape ADDA displays five reversible waves in a narrow range of 1.13 V. Two-photon absorption (TPA) measurement confirmed that the π-conjugation path is extended from 12 to ADDA and the molecular polarizability of ADA is larger than that of AAA.
Keywords: aromaticity; conjugation; molecular wires; porphyrin tapes; porphyrinoids.
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