Synthesis and properties of hybrid porphyrin tapes |
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Authors: | Tanaka Takayuki Lee Byung Sun Aratani Naoki Yoon Min-Chul Kim Dongho Osuka Atsuhiro |
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Institution: | Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan. |
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Abstract: | Hybrid porphyrin tapes 3 and 4 , consisting of a mixture of 3,5‐di‐tert‐butylphenyl‐substituted donor‐type ZnII–porphyrins and pentafluorophenyl‐substituted acceptor‐type ZnII–porphyrins, were prepared by a synthetic route involving cross‐condensation reaction of a NiII–porphyrinyldipyrromethane and pentafluorophenyldipyrromethane with pentafluorobenzaldehyde followed by appropriate demetalation, remetalation, and oxidative ring‐closure reaction. The NiII‐substituted porphyrin tapes 5 (Ni‐Zn‐Ni) and 6 (Ni‐H2‐Ni) were also prepared through similar routes. The hybrid porphyrin tapes 3 and 4 are more soluble and more stable than normal porphyrin tapes 1 and 2 consisting of only donor‐type ZnII–porphyrins. The solid‐state and crystal packing structures of 3 , 4 , and 5 were elucidated by single‐crystal X‐ray diffraction analysis. Singly meso–meso‐linked hybrid porphyrin arrays 12 and 14 exhibit redox potentials that roughly correspond to each constituent porphyrin segments, while the redox potentials of the hybrid porphyrin tapes 3 and 4 are positively shifted as a whole. The two‐photon absorption (TPA) values of 1–6 were measured by using a wavelength‐scanning open aperture Z‐scan method and found to be 1900, 21 000, 2200, 27 000, 24 000, and 26 000 GM, respectively. These results illustrate an important effect of elongation of π‐electron conjugation for the enhancement of TPA values. The hybrid porphyrin tapes show slightly larger TPA values than the parent ones. |
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Keywords: | aromaticity conjugation molecular wires nonlinear optics porphyrinoids |
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