Research Projects of Tani’s Group
1. Synthesis and photoelectronic properties of novel polycyclic pi-electroncompounds
Aromatic diimide compounds such as naphthalene diimide (NDI) andperylene diimide (PDI) have attracted much attention as electron acceptors,
n-typesemiconductors,

chromophores in visible region
andbuilding

supramolecular

blocksofarchitectures.

Besides NDI and PDI, tetracene
diimide (TDI) is also expected toexhibit intriguing electronic andphotophysicalproperties

sinceTDI possesses linearly extended
π-conjugated system. However,

Figure 1	  Chemical structure of TA-fused
TDI and its cyclic voltammogram (CV)there have been only limited TDI derivatives reported in a few papers. Herein,
we have designed a further π-extended TDI by fusing azulene as a10π-conjugating unit. Azulene is a unique molecule, which has a dipole momentof about 1.08 D along the C2-C6 axis to afford electron-donating five-memberedring and electron-withdrawing seven-membered ring. Hence, bonding offive-membered ring of azulene to a diimide core is anticipated to realize effective
donor-acceptor interaction and π-extension, leading to a smaller HOMO-LUMO
gap and characteristic photophysical and electronic properties. TA-fused TDI
exhibited four reversible one-electron reduction processes at –0.77, –1.08, –1.97, –2.12 V versus the Fc/Fc+ with a remarkable small HOMO-LUMO gap(0.96 eV). Absorption spectrum of TA-fused TDI exhibited intense absorption
bands at 343, 410, 426, 600, 651 nm derived from TDI skeleton, and a broad
low-energy band centered at 946 nm. The edge of the lowest-energy absorption
band reached ca. 1400 nm corresponding to the energy gap of 0.89 eV, which isin good agreement with the electrochemical HOMO-LUMO gap. The
Two-photon absorption (TPA) cross-section of TA-fused TDI was determined tobe σ(2) = 2140 GM at 950 nm (1 GM = 10-50 cm4 s photon-1 molecule-1). The

electron mobility of a thin film of TA-fused TDI prepared on an ITO /glass
substrate was revealed to be µ = 1.7×10–4 cm2 V–1 s–1 by space charge limited
current (SCLC) method.
[1] T. Koide, M. Takesue, T. Murafuji, K. Satomi, Y. Suzuki, J. Kawamata, K.
Terai, M. Suzuki, H. Yamada, Y. Shiota, K. Yoshizawa, F. Tani, Chem Plus
Chem, 2017, 82, 1010-1014.

2. Photochemical energy conversion based on supramolecular assembliesof porphyrin and fullereneWe

havepreparednickelcomplexes

andfree-bases of cyclic porphyrin dimers linked bybutadiyne or phenothiazine groups. The porphyrin
dimers have self-assembling pyridyl groups at theopposite meso positions and include fullerenes suchas C60, PCBM, C70 and Li+@C60 to give π-complexes.
Inparticular,thephenothiazine-bridged

cyclicporphyrin dimers exhibit notable high affinities toward
C60 (Kassoc>106 M-1) and C70 (Kassoc>107 M-1). In thecrystal structures, the π-complexes of C60 and PCBM
within the butadiyne-bridged nickel dimer and thephenothiazine-bridged

free-basedimer

affordself-assembled porphyrin nanotubes containing thelinear arrays of the fullerenes. These self-assemblies
are formed by the C-H···N hydrogen bonds and π-πinteractions of the meso pyridyl groups. On the otherFigure 2 Cyclic porphyrin
dimershand, the π-complexes of C60 and C70
within the butadiyne-bridged free-basedimer gave the zigzag chains of thefullerenes through van der Waals contacts
with each fullerene. These well-ordered
C60 arrays yield high electron mobilities

Figure 3	  Porphyrin nanotube and C 60 inporphyrin nanotube

(Σµ>10-1

cm2V-1s-1).

The

π-complexes

ofandLi+@C60

withinbutadiyne-bridgedperform

C60

thedimers

photoinduced

electron transfer from theporphyrins to the fullerenes
to give the CS states. The
π-complexes of Li+@C60 with

Figure 4 Formation of self-assembled
nanotube and linear array of fullereneporphyrin

the butadiyne-bridged dimers afford the CS states of remarkably long lifetimes
reaching submillisecond order.
[2] H. Nobukuni, Y. Shimazaki, F. Tani*, Y. Naruta, A Nanotube of Cyclic
Porphyrin Dimers Connected by Nonclassical Hydrogen Bonds and Its
Inclusion C60 in a Linear Arrangement, Angew. Chem. Int. Ed., 2007, 46,8975-8978 (Hot Paper).
[3] H. Nobukuni, F. Tani*, Y. Shimazaki, Y. Naruta, K. Ohkubo, T. Nakanishi, T.
Kojima, S. Fukuzumi, S. Seki, Anisotropic High Electron Mobility andPhotodynamics of a Self-Assembled Porphyrin Nanotube Including C60
Molecules, J. Phys. Chem. C, 2009, 113, 19694-19699.
[4] H. Nobukuni, Y. Shimazaki, H. Uno, Y. Naruta, K. Ohkubo, T. Kojima, S.
Fukuzumi, S. Seki, H. Sakai, T. Hasobe, F. Tani*, Supramolecular Structures
and Photoelectronic Properties of the Inclusion Complex of a Cyclic
Free-Base Porphyrin Dimer and C60, Chem. Eur. J., 2010, 16, 11611-11623.
[5] H. Nobukuni, T. Kamimura, H. Uno, Y. Shimazaki, Y. Naruta, F. Tani*,Supramolecular Structures of Inclusion Complexes of C70 and Cyclic
Porphyrin Dimers, Bull. Chem. Soc. Jpn., 2011, 84, 1321-1328 (BCSJAward).
[6] H. Nobukuni, T. Kamimura, H. Uno, Y. Shimazaki, Y. Naruta, F. Tani*,Supramolecular Structures of Inclusion Complexes of Cyclic Porphyrin
Dimers and [6,6]-Phenyl-C61-Butyric Acid Methyl Ester (PCBM), Bull. Chem.
Soc. Jpn., 2012, 85, 862-868. (Selected Paper)[7] T. Kamimura, K. Ohkubo, Y. Kawashima, H. Nobukuni, Y. Naruta, F. Tani*, S.
Fukuzumi, Submillisecond-lived photoinduced charge separation in inclusion
complexes composed of Li+@C60 and cyclic porphyrin dimers, Chem. Sci.,
2013, 4, 1451-1461.
[8] K. Sakaguchi, T. Kamimura, H. Uno, S. Mori, S. Ozako, H. Nobukuni, M.
Ishida, F. Tani*, Phenothiazine-Bridged Cyclic Porphyrin Dimers as
High-Affinity Hosts for Fullerenes and Linear Array of C60 in Self-Assembled
Porphyrin Nanotube, J. Org. Chem., 2014, 79, 2980-2992.
[9] T. Kamimura, K. Ohkubo, Y. Kawashima, S. Ozako, K. Sakaguchi, S.
Fukuzumi, F. Tani*, Long-Lived Photoinduced Charge Separation inInclusion Complexes Composed of a Phenothiazine-Bridged Cyclic Porphyrin
Dimer and Fullerenes, J. Phys. Chem. C, 2015, 119, 25634–25650.

3. Development of new carbon materials made from organic molecular
crystals
We have developed a new synthesis route for alternative catalysts of noble
metals for versatile chemical reactions that could help address environmental
concerns.
Noble metals such as platinum are useful as catalysts for versatile chemicalFigure 5 Synthesis schemes of (a) conventional carbonaceous catalysts and (b) this workfor ordered carbonaceous frameworks.

reactions including fuel cell vehicles and reduction of CO2 emission. However,they are too costly to be used for these purposes.
As inexpensive alternatives, organic-based catalysts and carbonaceous
catalysts were explored, but were ultimately found to be impractical. This wasbecause organic-based catalysts tend to be active but unstable, whilecarbonaceous catalysts are stable but less active.

In this work, we have found a solution by developing a new synthesis route forintermediate materials of organic-based catalysts and carbonaceous catalysts.
While conventional carbonaceous catalysts have amorphous carbonaceous
structures that cause a decline in catalytic activities (Figure 5a), the newsynthesis route enables the formation of carbonaceous catalysts with controlled
chemical structures like organic-based catalysts (Figure 5b). This synthesis
route is capable of developing alternative catalysts of noble metals for many
eco-friendly technologies such as fuel cell vehicles, hydrogen generation fromwater and CO2 reduction.
[10] H. Nishihara, T. Hirota, K. Matsuura., M. Ohwada., N. Hoshino., T.
Akutagawa., T. Higuchi., H. Jinnai., Y. Koseki., H. Kasai., Y. Matsuo., J.
Maruyama., Y. Hayasaka., H. Konaka., Y. Yamada., S. Yamaguchi., K.
Kamiya., T. Kamimura., H. Nobukuni., F. Tani*,.Synthesis of orderedcarbonaceous frameworks from organic crystals, Nature Commun., 2017,8, DOI: 10.1038/s41467-017-00152-z.

Press Release from Kyushu University (3, August, 2017)
http://www.kyushu-u.ac.jp/en/researches/view/66）