ISBN: 978-83-60043-10-3 - eurobic9

Eurobic9, 2-6 September, 2008, Wrocław, Poland
P143. High Selective Epoxidation of Cyclohexene by Non-heme Ruthenium
Complexes Incorporated into Mesoporous Silicate
K. Okumura, K. Jitsukawa, T. Ozawa, Y. Funahashi, and H. Masuda
Department of Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology,
Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
e-mail: masuda.hideki@nitech.ac.jp
Binding and activation of oxygen species in biological metallo-enzymes are regulated by the metal coordination
structures and the non-covalent interaction groups surrounding them, such as hydrophobic and hydrogen bonding
interaction ones. On the basis of the active site structures in biological systems, we have designed and
synthesized some new artificial metallo-enzymes containing transition metal ions. The objective of our research
project is to construct the artificial metallo-enzymes using these transition metal complexes and to develop
environmentally-benign catalysts. We recently prepared the biomimetic materials consisted of metal complexes
as an active site and nanoporous silicate as a reaction field, and the oxidation reaction with some substrates were
carried out.[1][2][3] In this paper, we newly designed and synthesized new ruthenium(II) complex of 6,6’bis(benzoylamido)-2,2’-bipyridine
(BABP) as an oxidation catalyst. This catalyst exhibited high efficient
oxidations for cyclohexene when tert-butyl hydroperoxide was employed as an oxidant, but it does not show any
selectivity. So we tried the immobilization of the ruthenium(II) complex into the nanoporous silicate FSM-16
that is often used as the substrate-specific reaction field in biological enzyme systems. Interestingly, it showed a
higher epoxidation selectivity for cyclohexene. The material after the oxidation reaction was ESR active,
indicating that the starting material for the catalytic reaction is Ru(III) species and the oxidation active species is
Ru(V)=O. So we can propose that the oxidation reaction was carried out with cycle of Ru(III) and Ru(V)=O.
Interestingly, this Ru(III) species was repeatedly used for epoxidation reaction. These findings indicate the
nano-silicate FSM-16 can stabilize the active species and promote the effective capturing of the substrates.
Acknowledgment: We gratefully acknowledge the support of this work from a Grant-in-Aid for Scientific
Research from the Ministry of Education, Science, Sports and Culture, and in part by a grant from the NITECH
21st Century COE program.
References:
[1] T. Okumura, H. Takagi, Y. Funahashi, T. Ozawa, Y. Fukushima, K. Jitsukawa, and H. Masuda, Chem. Lett.,
36, 122-123 (2007)
[2] Y. Honda, H. Arii, T. Okumura, A. Wada, Y. Funahashi, T. Ozawa, K. Jitsukawa, and H. Masuda, Bull.
Chem. Soc. Jpn. (Accounts, Invited), 80, 1288-1295 (2007).
[3] T. Okumura, Y. Morishima, H. Shiozaki, T. Yagyu, Y. Funahashi, T. Ozawa, K. Jitsukawa, and H. Masuda,
Bull. Chem. Soc. Jpn., 80, 507-517 (2007).
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