著者
Naoki Aratani Atsuhiro Osuka
出版者
(社)日本化学会
雑誌
Bulletin of the Chemical Society of Japan (ISSN:00092673)
巻号頁・発行日
vol.88, no.1, pp.1-27, 2015-01-15 (Released:2015-01-15)
参考文献数
241
被引用文献数
35 1

Directly linked linear porphyrin arrays were synthesized and their photophysical properties depending on the length of the arrays were investigated. Ag(I)-promoted oxidative coupling of 5,15-diaryl Zn(II) porphyrins has proven to be effective for preparations of very long meso–meso-linked Zn(II) porphyrin arrays (Zn). A stepwise doubling strategy with strict purification at each doubling step allowed for preparation of gigantic but discrete linear arrays in an unprecedented manner. Large cyclic porphyrin wheels were also synthesized by final meso–meso coupling intramolecular cyclization. Crucial to this success are high reactivity and high regioselectivity of the Ag(I)-promoted oxidative coupling. Equally important are high solubilities of Zn despite their large molecular weights, which arise from their perpendicularly linked structures. Another advantage of this doubling strategy is a large difference in the molecular weights among reactants and products that increases as the reactant array becomes larger, allowing separation of coupling products by preparative GPC-HPLC. As an alternative protocol, Pd-catalyzed Suzuki–Miyaura cross-coupling has been extensively used for synthesis of cyclic porphyrin arrays. This strategy gave novel linear and cyclic porphyrin arrays from β-borylated porphyrins that were prepared by Ir-catalyzed borylation of meso-free porphyrins. As an interesting example, a porphyrin nanotube consisting of four porphyrins doubly bridged by 2,6-pyridinylene spacers was synthesized and revealed to possess a C60-encapsulation capability. Exciton coupling, effective energy hopping, coherent length, and excitation energy transfer of meso–meso-linked linear and cyclic porphyrin arrays are discussed. STM and AFM detections of the large porphyrin arrays are also presented. We believe that these studies expand the range of organic molecules we can manipulate and open a door to a new area of nanoscaled and sub-microscaled functional porphyrin materials.
著者
Atsuhiro Osuka Hitomi Suzuki Kazuhiro Maruyama
出版者
(社)日本化学会
雑誌
Chemistry Letters (ISSN:03667022)
巻号頁・発行日
vol.11, no.5, pp.653-656, 1982-05-05 (Released:2006-03-27)
参考文献数
12
被引用文献数
1

Photolysis of the title compounds in benzene gave spirophthalides and E- and Z-alkylidene phthalides via preferential α-cleavage at the more crowded side. On the basis of quantum yields and triplet lifetimes, this preference is indicated to arise from the different efficiencies of the radical recombination of possible biradicals.
著者
Kazuhiro Maruyama Atsuhiro Osuka Katsuhiko Nakagawa Kenzo Tabuchi Hirohito Shimizu Hitomi Suzuki
出版者
(社)日本化学会
雑誌
Chemistry Letters (ISSN:03667022)
巻号頁・発行日
vol.15, no.11, pp.1849-1852, 1986-11-05 (Released:2006-03-27)
参考文献数
7
被引用文献数
1

Irradiation of 2-substituted 4-alkylidene-2,3-epoxy-1-tetralone results in the rearrangement to 3-(2-oxoalkylidene)-1-indanone or the E-Z isomerization around the double bond. These photoreactions are suggested to occur from the (π,π*) triplet excited state.
著者
Kazuhiro Maruyama Hiroko Yamada Atsuhiro Osuka
出版者
(社)日本化学会
雑誌
Bulletin of the Chemical Society of Japan (ISSN:00092673)
巻号頁・発行日
vol.63, no.12, pp.3462-3466, 1990 (Released:2006-06-05)
参考文献数
19
被引用文献数
5

We applied the Chemically Induced Dynamic Nuclear Polarization (CIDNP) technique to the photochemical reaction of pheophytin a (P1) and 4-methoxyphenol (1) in benzene-d6. The observed CIDNP effects were explained in terms of reversible electron-transfer reactions from 1 to 3(P1)* and from (P1)\ ewdot to (1)\underset.+. The polarized signals of P1 were induced from the in-cage recombination of the triplet radical ion pair.
著者
Hirofumi Nakamura Masahide Terazima Noboru Hirota Satoshi Nakajima Atsuhiro Osuka
出版者
(社)日本化学会
雑誌
Bulletin of the Chemical Society of Japan (ISSN:00092673)
巻号頁・発行日
vol.68, no.8, pp.2193-2202, 1995 (Released:2006-07-09)
参考文献数
37
被引用文献数
11

Charge separated ion-pair (IP) states formed from three distance-fixed photosynthetic triads were studied by the time-resolved EPR method. Upon photoexcitation of the triads in THF at 77 K, small and narrow signals were observed at the central parts of broad EPR spectra due to the excited triplet states of the chromophores. These signals were assigned to secondary, fully charge separated IP states by the simulation based on the spin-correlated radical pair mechanism. Time dependence of the TREPR signals indicates that charge separation occurs in the singlet manifold as in the case of the photoexcited state dynamics at room temperature. Estimated electron exchange interactions, J, are in the order of 10−2—10−3 mT, which is in line with the observed long lifetimes of the IP states.