2nd OUS Frontier Symposium
Functional Complexes and Their New Applications
March 3, 2023
KAKE Educational Institution ⚫ 50th Anniversary Hall
Okayama University of Science,Okayama, Japan
Organized by Institute of Frontier Science and Technology, Okayama University of Science

Scientific Program
13:00
Opening Ceremony

Haruo Akashi (Director, Institute of Frontier Science and Technology)

13:05 – 13:55
Guest Lecturer 1
Shie-Ming Peng (National Taiwan University)
From Metal-Metal Multiple Bonds to Helical Metal Strings
13:55 – 14:45
Guest Lecturer 2
Hitoshi Ishida (Kansai University)

Chairperson: Haruo Akashi

Chairperson: Minoru Mitsumi

Photocatalytic CO2 Reduction by Ruthenium Complexes towards Artificial Photosynthesis
14:45 – 15:15 Coffee Break
15:15 – 16:05
Guest Lecturer 3
Chairperson: Haruo Akashi
Akitaka Ito (Kochi University of Technology)
Controlling Photofunctionalities of Metal Complexes by Electrostatic Interactions
16:05
Closing Ceremony

Yoshiko Minami (Vice President, Okayama University of Science)

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2nd OUS Frontier Symposium, 2023, Okayama University of Science

From Metal-Metal Multiple Bonds to Helical Metal Strings
Shie-Ming Peng*
Department of Chemistry, National Taiwan University, Taipei Taiwan
Institute of Chemistry, Academia Sinica, Taipei Taiwan*E-mail: smpeng@ntu.edu.twThe study of metal string complexes with 1-D transition metal frameworks (Fig.1) began in theearly 1990s. Since these complexes provide great insight into multiple metal-metal bonds, and may
have potential applications as molecular wires (Fig.2), this field of research has grown in the past
20 years. As such, the electronic structure of the simplest trinuclear complexes, the supporting ligand
systems, and single molecular conductance of metal string complexes are discussed. This review
will introduce the development of this field and summarize some important results in the newly
designed heteronuclear metal string complexes (HMSCs). These molecules may be of great interestin studying the nature of heterometallic electronic effects and molecular electronic applications.

Figure 1: Molecular Model of Metal String
Complex with Quadruple Ligands

Figure 2: An Electric Wire and aMiniature Molecular Metal Wire

[1] Ismayilov RH, Wang WZ, Lee GH, Yeh CY, Hua SA, Song Y, Rohmer MM, Bénard M, Peng
SM, Angew. Chem. Int. Ed., 2011, 50, 2045-2048.
[2] Hua SA, Cheng MC, Chen C-h, and Peng SM, Eur. J. Inorg. 2015, Micro Review, 15, 2498.
[3] Ting TC, Hsu LY, Huang MJ, Horng EC, Lu HC, Hsu CH, Jiang CH, Jin BY, Peng SM andChen Ch, Angew. Chem. Int. Ed., 2015, 54, 15734-15738.
[4] Liu YC, Hua SA, Cheng MC, Yu LC, Demeshko S, Dechert S, Meyer F, Lee GH, Chiang MH,Peng SM, Chem-Eur J, 2018, 24(45), 11649-11666.
[5] Cheng MC, Huang RX, Liu YC, Chiang MH, Lee GH, Song Y, Lin TS, Peng SM, Dalton
Trans., 2020, 49(22), 7299-7303.

2nd OUS Frontier Symposium, 2023, Okayama University of Science

Photocatalytic CO2 Reduction by Ruthenium Complexes
towards Artificial Photosynthesis
Hitoshi Ishida*
Department of Chemistry and Materials Engineering, Faculty of Chemistry, Materials andBioengineering, Kansai University, Suita, Osaka, Japan*E-mail: ishida.h@kansai-u.ac.jp
Photocatalytic CO2 reduction is attracting much attention from the viewpoints of the utilization ofsolar energy and recycling of CO2 and is expected as a central technology in artificial
photosynthesis.[1] In this lecture, the catalytic abilities of trans(Cl)-Ru(bpy)(CO)2Cl2 (bpy: 2,2’bipyridine) and the derivatives for CO2 reduction will be described (Figure 1).[2] The reaction
mechanism is elucidated in many parts but
remains unknown in some features.[3]The photocatalytic CO2 reduction
proceeds by irradiating visible light (> 400nm)
intheN-dimethylacetamide(DMA)/water (9:1 v/v) solution containing[Ru(bpy)3]2+ as the photo-sensitizer, 1benzyl-1,4-dihydronicotinamide (BNAH)
as the electron donor and the catalyst. The
reaction mechanism does not only dependon the electronic structures of the catalysts
but also the reaction conditions such as thecatalyst concentrations. It also depends onthe electron-injection speeds from the oneelectron reduced species of photo-sensitizer
to the catalyst.
The application of the photocatalytic
CO2
reduction
towards
artificial
photosynthesis will be discussed.

Figure 1.
Photocatalytic CO2 Reduction bytrans(Cl)-[Ru(bpy)(CO)2Cl2] and the derivatives.

[1] Ishida, H. (2018), Electrochemical / Photochemical CO2 Reduction Catalyzed by Transition
Metal Complexes, in “Carbon Dioxide Chemistry, Capture and Oil Recovery”, Iyad Karamé,Janah Shaya, Hassan Srour (Eds), InTech, pp. 17-40, DOI: 10.5772/intechopen. 75199.
[2] Ishida, H., et al., ChemPhotoChem, 2018, 2, 314-322; Chem. Eur. J., 2017, 23, 10301-10309;
Faraday Discussions, 2017, 198, 263-277; Chem. Eur. J., 2015, 21, 10049-10060; Chem. Sci.,
2015, 6, 3063-3074; Inorg. Chem., 2014, 53, 3326-3332.
[3] Kuramochi, Y.; Osamu Ishitani, O.; Ishida, H., Coord. Chem. Rev. 2018, 373, 333-356.

2nd OUS Frontier Symposium, 2023, Okayama University of Science

Controlling Photofunctionalities of Metal Complexes
by Electrostatic Interactions
Akitaka Ito1,2,*12

Graduate School of Engineering, Kochi University of Technology, Kami, Kochi, Japan
Research Center for Molecular Design, Kochi University of Technology, Kami, Kochi, Japan*E-mail: ito.akitaka@kochi-tech.ac.jp

Metal-to-ligand charge transfer (MLCT) excited states of dπ6-type transition metal complexes
represented by [Ru(bpy)3]2+ (bpy = 2,2′-bipyridine) have been utilized in various photochemical
applications such as solar–energy conversion systems, light-emitting devices and sensing owing totheir intense visible-light absorption and phosphorescence from the long-lived triplet excited state [1].
Therefore, controlling their photofunctionalities (e.g., light absorption, emission and photoinduced
reaction behaviors) is of primary importance. There are numerous reports on synthetic tuning of theelectronic structures of a complex by varying a combination of metal center and ligands and/or by
introducing a functional group(s) in a ligand(s) [2]. In addition to such synthetic strategy, surrounding
environment is another important factor to characterize the photofunctionalities of a metal complex[3]. Here, we focused on electric charges of metal complexes and succeeded in tuning photophysical/photochemical properties of ionic metal complexes by hybridizing with ionic nanospheres,a class of ion-exchange resins with a diameter of <300 nm.
Polypyridyl ruthenium(II)/osmium(II) and cyclometalated iridium(III) complexes doped in theionic nanospheres exhibited intense and long-lived emission arising from decreased nonradiative
decay rate constants. Such long-lived excited states of the metal complexes in the nanospheres areadvantageous for photosensitized reactions, and multiple ionic species can be doped in a nanosphere.
In practice, emission from [Ru(bpy)3]2+ in the nanosphere was reduced in the presence of codoped
methyl viologen dication (MV2+), and >60% quenching was obtained even by 100 nmol/mg MV2+
(almost equivalent to [Ru(bpy)3]2+ content) [4]. Similar efficient photoinduced reaction was also
observed in the energy-transfer systems.
[1] Thompson, D. W.; Ito, A.; Meyer, T. J. Pure Appl. Chem. 2013, 85, 1257.: Ito, A.; Iwamura, M.;
Sakuda, E. Coord. Chem. Rev. 2022, 467, 214610.
[2] Ito, A.; Kang, Y.; Saito, S.; Sakuda, E.; Kitamura, N. Inorg. Chem. 2012, 51, 7722.: Ito, A.;
Kobayashi, N.; Teki, Y. Inorg. Chem. 2017, 56, 3794.: Ito, A.; Matsui, Y. Inorg. Chem. 2019, 58,10436 [Supplementary Cover].
[3] Ito, A.; Stewart, D. J.; Fang, Z.; Brennaman, M. K.; Meyer, T. J. Proc. Natl. Acad. Sci. 2012,109, 15132.: Ito, A.; Meyer, T. J. Phys. Chem. Chem. Phys. 2012, 14, 13731.: Ito, A.; Fang, Z.;
Brennaman, M. K.; Meyer, T. J. Phys. Chem. Chem. Phys. 2014, 16, 4880.
[4] Yamamoto, H.; Taomoto, M.; Ito, A.; Kosumi, D. J. Photochem. Photobiol. A: Chem. 2020, 401,112771.