Ken-ichi Sugiura

Tropolone as a High-Performance Robust Anchoring Group for Dye-Sensitized Solar Cells

A tropolone group has been employed for the first time as an anchoring group for dye-sensitized solar cells (DSSCs). The DSSC based on a porphyrin, YD2-o-C8T, with a tropolone moiety exhibited a power-conversion efficiency of 7.7u2009%, which is only slightly lower than that observed for a reference porphyrin, YD2-o-C8, with a conventional carboxylic group. More importantly, YD2-o-C8T was found to be superior to YD2-o-C8 with respect to DSSC durability and binding ability to TiO2 . These results unambiguously demonstrate that tropolone is a highly promising dye-anchoring group for DSSCs in terms of device durability as well as photovoltaic performance.

Synthesis and properties of cis - 1,2 - bis (octaethylporphyrinyl)ethylene

Abstract A new cis-form of ethylene-bridged octaethylporphyrin dimer 3a has been obtained by isomerization of the corresponding trans-isomer 2a . On the basis of spectral data the structure of 3a was assigned to be close to a “face-to-face” orientation. Reflecting the peculiar structure of 3a UV-vis and 1 H NMR spectra are remarkably distinguished from those of ordinary porphyrins.

Ionic Channel Structures in [(M+)x([18]crown‐6)][Ni(dmit)2]2 Molecular Conductors

The [(M+)x[18]crown-6)] supramolecular cations (SC+), in which M+ and [18]crown-6 are alkali metal ions (M+ = Li+, Na+, and Cs+) and 1,4,7,10,13,16-hexaoxacyclooctadecane, respectively, form ionic channel structures through the regular stacks of [18]crown-6 in [Ni(dmit)2]-based molecular conductors (dmit2+ = 2-thioxo-1,3-dithiole-4,5-dithiolate). In addition to the [Ni(dmit)2] salts that have the ionic channel structures (these salts are abbreviated as type I salts), Li+ and Na+ form dimerized [(M+)2([18]crown-6)2] units in the crystals (type II salts). The K+ and Rb+ are coordinated tightly into the [18]crown-6 cavity to form typical disk-shape SC+ units in the corresponding [Ni(dmit)2] salts (type III salts). The type I, II, and III salts have typical stoichiometries of [(M+)x([18]crown-6)][Ni(dmit)2]2, [(M+)([18]crown-6)(H2O)x(CH3CN)(1.5 - x)][Ni(dmit)2]3 (x = 1 for Li+ or 0.5 for Na+), and [M+([18]crown-6)][Ni(dmit)2]3, respectively: the salts of the same type are isostructural. In agreement with the trimer structures of [Ni(dmit)2] in the type II and III salts, they exhibit semiconducting behavior with electrical conductivities at 300 K (sigma(300 K)) of 0.01-0.1 S cm(-1). Type I salts contain a regular stack of partially oxidized [Ni(dmit)2] units, which form a quasi one-dimensional metallic band within the tight-binding approximation regime. The electrical conductivities at 300 K are 10-30 S cm(-1), and an almost temperature-independent conductivity was observed at higher temperatures. However, the one-dimensional electronic structures in these salts are strongly influenced by the static and dynamic structures of the coexisting ionic channel. The Na+ salt is a semiconductor, whose magnetic behavior is described by the disordered one-dimensional antiferromagnetic chain. On the other hand, the Cs+ salt is a exhibits metallic properties with 2 kF instability at room temperature. The Li+ salt shows a gradual transition from the high-temperature metallic phase to the low-temperature one-dimensional antiferromagnetic semiconductor phase, which was associated with the freezing of Li+ motion at lower temperatures. The preferential crystallization of type I salts was possible by controlling the equilibrium constant (Kc) of the complex formation between M+ ions and the [18]crown-6 molecule. The ionic channel structures were obtained when the KC was low in the electrocrystallization solution, while type II or III salts were formed in the high Kc region.

SYNTHESIS AND PROPERTIES OF ETHENO-BRIDGED PORPHYRIN TRIMERS

The etheno-bridged porphyrin trimer was synthesized by an intermolecular cross coupling of the meso-alcohols, followed by dehydrogenation from the ethano linkages. Its basicity and electron releasing ability increased compared with octaethylporphyrin (OEP) and the etheno-bridged porphyrin dimer.

Fabrication of molecular alignment at the specific sites on Cu(111) surfaces using self-assembly phenomena

Abstract We have successfully controlled the low-dimensional self-assembly formation of adenine molecules, one of the base molecules of DNA, between pre-adsorbed OMTP (2,3,7,8,12,13,17,18-octakis(methilthio)porphyrin) molecules which are immobile on Cu(111) surfaces even at room temperature. The results of low temperature (approximately 70xa0K) scanning tunneling microscopy observation and molecular orbital calculation have revealed that OMTP molecules can connect with adenine molecules through hydrogen bonds to act as ‘hub-molecules’, i.e. as an anchoring site for their self-assembly. This study demonstrates a new concept and the first attempt to control the self-assembly formation at molecular level using these hub-molecules.

Self-assembled stripe structure of zinc–phthalocyanine on graphite surfaces

Abstract Monolayers of zinc–phthalocyanine deposited on highly oriented pyrolytic graphite (HOPG) substrate have been investigated by scanning tunneling microscopy. At the coverage of 1 ML, ZnPc layers show stripes with twined domains along threefold symmetry. The separations between the stripe lines are 6 nm and the heights of the monolayers are 1.2 nm. This structure can be explained by a corresponding superstructure for monolayered β-form ZnPc crystals with the π-stacking in parallel to the HOPG surface.

Synthesis and Properties of Tris(octaethylporphyrin)s Connected with Vinylene Groups

Tris(octaethylporphyrin)s, in which two octaethylporphyrin (OEP) rings are connected with vinylene groups at α,γ- and α,β-meso positions of the central OEP ring, were synthesized. The tris(OEP)s have similar conformational and configurational structures to the corresponding vinylene group-connected bis(OEP). Examination of both 1H NMR and electronic absorption spectra of the tris(OEP)s showed the behavior reflecting the highly symmetrical structure and the mutual interaction between the three OEP rings through the vinylene linkages.

A porphyrin square: synthesis of a square-shaped π-conjugated porphyrin tetramer connected by diacetylene linkages

A square-shaped π-conjugated porphyrin tetramer has nprepared: the excitation energies of both the Soret and Q bands, 19880 n(503) and 15180 cm−1 (659 nm), respectively, are quite low ncompared with those for the monomer and reported cyclic porphyrin noligomers.

Structural Diversity in Rubyrins: X-ray Structural Characterisation of Planar and Inverted Rubyrins

Meso aryl rubyrins exhibit three different structures. A planar (7) and two unusual inverted structures (8 and 9) have been characterised by X-ray and NMR spectroscopy.

Structure and magnetic properties of meso-tetrakis(2,4,6-trimethylphenyl)porphyrinatomanganese(III) 7,7,8,8-tetracyano-2,5-dimethyl-p-quinodimethanide with a 2.3 K Tc. The first example of cis coordination of a tetracyano-p-quinodimethanide

The crystal structure of meso-tetrakis(2,4,6-trimethylphenyl)porphyrinatomanganese(III) 7,7,8,8-tetracyano-2,5-dimethyl-p-quinodimethanide, [MnTMesP][DMTCNQ]·2p-C6H4Me2 provides the first example of a cis-1,2-μ-coordination motif having an infinite zigzag chain structure. [MnTMesP][DMTCNQ]·2p-C6H4Me2 crystallizes in a triclinic space group. The zigzag one-dimensional (1-D) chain is non-uniform and each acceptor does not lie on a centre of symmetry, although all acceptors are crystallographically equivalent. The ionic ground state of the complex was determined on the basis of X-ray photoelectron spectroscopy, crystallographic data, as well as the νCN at 2184 and 2160xa0cm−1. The susceptibility (χ) of the complex obeys the Curie–Weiss equation, χ = 1/(T n− nθ), where θ is −10 ± 1xa0K (130 250xa0K). A minimum of χT(T) characteristic of 1-D antiferromagnetic coupling is observed at 115xa0K. Above 50xa0K, χT(T) can be fitted by the Seiden model for non-interacting chains comprised of alternating g = 2, quantum S = 2 and classical S = 1/2 spins, with J/kB = −39xa0K for H = −2JSi·Sj. The in-phase component, χ′(T), in a.c. susceptibility measurements shows a sharp maximum at 2.3xa0K associated with the ordering temperature, Tc, of the material.