Slippage- and load-induced changes in the crystalline orientation of oligo(3-methoxythiophene) powder to develop a gold-tone luster.

The achievement of molecular orientation control by rubbing and pressing poly(3-alkylthiophene)s is a powerful technique to improve the performance of organic electronic devices. We report here that the rubbing and pressing of blackish-brown 3-methoxythiophene oligomer powders yield layer and tablet samples with gold tones, respectively. Specular reflectivity, colorimetric, and X-ray diffraction measurements reveal that this gold tone is caused by an increase in the ratio of edge-on lamellar crystallites to face-on ones, which is promoted by rubbing/pressing. In contrast to the 3-alkylthiophene polymer, which develops a dominant face-on lamellar structure, rubbing of the 3-methoxythiophene oligomer increases the relative amount of edge-on lamellar crystallites to face-on lamellar ones. Furthermore, gold tone development in the tablet samples is limited to the near-surface area, despite the fact that pressure is also applied to the tablet bulk. These specific chemical events are explained by considering the repulsive interactions between the 3-methoxythiophene backbone and the functional groups on the surface of the substrate employed during the rubbing/pressing processes. Despite the lower applied pressure, gold tone development by rubbing is accompanied by a higher reflective property than by pressing because of the formation of larger relative amounts and sizes of edge-on lamellar crystallites, which are responsible for the gold tone.

Preparation and Characterization of Electric Double-Layer Capacitors Having a 3D Stainless-Steel Fiber Sheet as the Current Collector.

One strategy to improve the performance of electric double-layer capacitors (EDLCs) is changing the current collector material. In this study, a three-dimensional porous current collector comprising stainless-steel fibers is fabricated using a relatively simple method. Capacitor properties of the EDLC using this unique current collector are characterized by cyclic voltammetry and charge-discharge tests. The voltammograms of the EDLC develop a more butterfly shape and an increased specific capacity at higher electrolyte concentrations. It shows reversible charge-discharge potential profiles, little capacity degradation (∼98% of the initial capacity at 1000th cycle), and a good rate performance at higher electrolyte concentrations (90% capacity retention for 2.5 times increase in discharge current). Its capacitance values (95-99 F g-1) are roughly twice the specific capacitance of an EDLC using the flat stainless-steel plate current collector (51 F g-1) without any performance degradation even at a higher loading of electrode active materials. Based on the AC impedance analysis, these good properties are attributed to the reduction in several resistances compared to the case of a flat stainless-steel plate: (i) the contact resistance between the electrode active material and the current collector, (ii) the resistance of the electrolyte in the finely branched space formed by the fibers and the active material, and (iii) the resistance in the diffusion layer. Increasing the electrolyte concentration further reduces the latter two resistances and the bulk electrolyte resistance, resulting in higher performance of the EDLC using the stainless-steel fiber sheet current collector.

Ethylene-bridged polysilsesquioxane/hollow silica particle hybrid film for thermal insulation material.

Ethylene-bridged polysilsesquioxane (EBPSQ) was prepared by the sol-gel reaction of bis(triethoxysilyl)ethane. The whitish slurry was prepared by mixing EBPSQ and hollow silica particles (HSPs) with a median diameter of 18-65 µm at 80 °C, and it formed a hybrid film by heating at 80 and 120 °C for 1 h at each temperature, then at 200 °C for 20 min. The surface temperatures of EBPSQ films containing 10 wt% and 20 wt% of HSPs (90.2 °C-90.5 °C) were lower than those of EBPSQ films (93.6 °C), when the films on the duralumin plate were heated at 100 °C for 10 min from the bottom of the duralumin plate. The thermal conductivity/heat flux (k/q) obtained from the temperature difference between the surface temperature and bottom temperature of the films and the film thickness also decreased with adding the HSPs. EBPSQ film without HSPs exhibited T 5 d of 258 °C and T 10 d of 275 °C. However, EBPSQ film containing 20 wt% of HSPs exhibited high thermal stability, and T 5 d and T 10 d were 299 °C and 315 °C, respectively. Interestingly, T 5 d and T 10 d of the hybrid films increased with an increase in the number of HSPs. Overall, it was shown that HSPs could improve the thermal insulation properties and thermal stability.

Benzenedithiolate-bridged MoFe complexes: structures, oxidation states, and reactivities.

Two benzendithiolate-bridged MoFe complexes, [(Me3P)2(CO)2Mo(µ-S2C6H4)Fe(CO)3] (1) and [(Me3P)(CO)3Mo(µ-S2C6H4)Fe(CO)3] (2), were synthesized by reacting [Mo(S2C6H4)(CO)2(PMe3)2] (3) with Fe(CO)5. Each complex has a direct Mo-Fe bond that is supported by a bridging benzenedithiolate ligand and a semi-bridging carbonyl ligand as elucidated by single-crystal X-ray diffractometry. The structural data and differences in reactivity of these complexes suggest that monophosphine complex 2 is formed via diphosphine complex 1. The reaction of 2 with PMe3 gives the diiron bis(dithiolate) complex, [Fe(S2C6H4)(CO)2(PMe3)]2 (4), rather than 1. 57Fe Mössbauer and X-ray photoelectron spectroscopy studies reveal the oxidation states of the metal centers in 2 to be Fe0 and MoII.

Model-based research toward design of innovative materials: molecular weight prediction of bridged polysilsesquioxanes.

Toward the design and manipulation of innovative materials, we propose a new concept called "model-based research (MBR)". In MBR, measurable physical and chemical properties of materials are mathematically modelled by explanatory parameters obtained by computer simulation from an atomistic point of view. To demonstrate the potential of MBR, we modelled the molecular weights of a series of polysilsesquioxanes with respect to the H2O/silane molar ratio employed for the polymerization of monomers bis(triethoxysilyl)methane, ethane, ethylene, and acetylene (BTES-M, -E1, -E2, and -E3), as an example. The equation y = ax n well reproduced the behaviour of the molecular weights of the BTES series, in which a and n were obtained using the calculated molecular parameters for monomers as the explanatory parameters. Detailed understanding and discussion were theoretically possible on the basis of the mathematical model. We predicted the molecular weights of polymers that would be obtained from monomers BTES-P and BTES-Ph with C3H6 and C6H4 as the spacer, respectively, using the mathematical model. Experimental validation of these polymers clearly showed the possibility of qualitative categorization. Our proposed concept, MBR, is a powerful tool to analyse materials science toward innovative materials design.

Preparation of Ruthenium Dithiolene Complex/Polysiloxane Films and Their Responses to CO Gas.

To develop advanced materials using metal complexes, it is better to prepare metal complexes contained in composite or hybrid films. To achieve this purpose, we synthesized ruthenium complexes with dihalogen-substituted benzendithiolate ligands, [(η6-C6Me6)Ru(S2C6H2X2)] (X = F, 3,6-Cl, Br, 4,5-Cl), 1b-1e. We also investigated preparation of 1c or 1e containing polysiloxane composite films and their reactivity to CO gas. All ruthenium complexes 1b-1e reacted with CO gas, and carbonyl ligand adducts 2b-2e were generated. Ruthenium complexes 1b-1e show two strong absorption peaks around 550 and 420 nm. After exposure to CO gas, these absorption peaks were immediately decreased without a peak shift. A similar trend was observed in 1c or 1e containing polysiloxane composite films. These results indicate that 1c and 1e were easily converted into 2c and 2e, both in the solution and the polysiloxane film during CO gas exposure.

The synthesis and structure of a dianionic species with a bond between pentacoordinated tin atoms: bonding properties of the tin-tin bond.

The first dianionic compound bearing a bond between two pentacoordinated tin atoms, a distannate, was synthesized in a stable form by using two sets of an electron-withdrawing C,O-bidentate ligand on each tin atom. The structure of the distannate was determined by NMR spectroscopy and X-ray crystallographic analysis. The Sn-Sn bond of the distannate was shown to be a single bond featuring high s-character. The 1J(Sn-Sn) coupling constant was larger than that of Sn(sp3)-Sn(sp3) bonds found in most hexaorganodistannanes. This bond feature was also supported by computational studies. The Sn-Sn bond was cleaved by treatment with hydrochloric acid, which shows a different reactivity to the homonuclear bonds of pentacoordinated disilicates and digermanates.

Carbon Monoxide Addition to Ruthenium-Dithiolene Complex and Polysiloxane Hybrid Film Formation.

The addition of carbon monoxide to the ruthenium center of [(η(6) -C6 Me6 )Ru(S2 C6 H4 )] (1) has been investigated. [(η(6) -C6 Me6 )Ru(CO)(S2 C6 H4 )] (2) was obtained by the addition of CO gas to the ruthenium center of 1 in both solution and solid states. 1 was reproduced by treating 2 with an oxidant. A 1/polysiloxane self-standing hybrid film was also prepared and showed a dramatic color change upon transformation of 1 to 2 in polysiloxane hybrid film.

π-Conjugated trinuclear group-9 metalladithiolenes with a triphenylene backbone.

Previously, we synthesized π-conjugated trinuclear metalladithiolene complexes based on benzenehexathiol (J. Chem. Soc., Dalton Trans.1998, 2651; Dalton Trans.2009, 1939; Inorg. Chem.2011, 50, 6856). Here we report trinuclear complexes with a triphenylene backbone. A reaction with triphenylenehexathiol and group 9 metal precursors in the presence of triethylamine gives rise to trinuclear complexes 9-11. The planar structure of 11 is determined using single crystal X-ray diffraction analysis. The ligand-to-metal charge transfer bands of 9-11 move to longer wavelengths compared with those of mononuclear 12-14. Electrochemical measurements disclose that the one-electron and two-electron reduced mixed-valent states are stabilized thermodynamically. UV-vis-NIR spectroscopy for the reduced species of 9 identifies intervalence charge transfer bands for 9(-) and 9(2-), substantiating the existence of electronic communication among the three metal nuclei. These observations prove that the triphenylene backbone transmits π-conjugation among the three metalladithiolene units.

Multinuclear metalladithiolenes: focusing on electronic communication in mixed-valent states.

This Perspective addresses our recent studies relating to metalladithiolenes and their cluster complexes that exhibit peculiar electronic communication in mixed-valent (MV) states. Chapter 1 provides an introduction for the Perspective. Chapter 2 enumerates a series of phenylene-annulated π-conjugated trinuclear metalladithiolenes with intense electronic communication in the MV states. Chapter 3 treats heterometal cluster complexes synthesized by integrating zero-valent metal carbonyls on mononuclear metalladithiolenes, taking advantage of the coordination unsaturation of the latter. In the field of MV chemistry, their electronic communication through metal-metal bonds and potential inversion behavior are intriguing properties. Chapter 4 describes hexanuclear and nonanuclear heterometal cluster complexes created in combination with the methods introduced in Chapters 2 and 3. The resultant heterometal cluster complexes feature electronic communication through the vast phenylene-annulated π-conjugated trinuclear metalladithiolene frameworks, the intensity of which correlates with their planarity. Each chapter describes the synthesis, structural features, and electrochemical properties of the relevant compounds.

Ir3Co6 and Co3Fe3 dithiolene cluster complexes: multiple metal-metal bond formation and correlation between structure and internuclear electronic communication.

π-Conjugated trinuclear iridium and cobalt dithiolenes undergo multiple metal-metal bond formation with Co(2)(CO)(8) and Fe(CO)(5), giving rise to Ir(3)Co(6) nonanuclear and Co(3)Fe(3) hexanuclear cluster complexes 5 and 6, respectively. 5 retains a planar framework and intense π conjugation across the three iridadithiolenes and the phenylene bridge, which results in intense electronic communication among the three Co(2)(CO)(5) units in reduced mixed-valent states.

Alkynylation of benzotriazole with silylethynyliodonium triflates. Regioselective synthesis of 2-ethynyl-2H-benzotriazole derivatives.

Phenyl(trimethylsilylethynyl)iodonium and tert-butyldimethylsilylethynyl(phenyl)iodonium triflates were applied to alkynylation of benzotriazole. Treatment of the silylethynyliodonium triflates with the potassium salt of benzotriazole ion in (t)BuOH and CH(2)Cl(2) gave 2-(trimethylsilylethynyl)-2H-1,2,3-benzotriazole and 2-(tert-butyldimethylsilylethynyl)-2H-1,2,3-benzotriazole in 74% and 76% yields, respectively. The regioisomers, 1-silylethynyl-1H-1,2,3-benzotriazole derivatives, were minor. In both cases of the silyl-substitued ethynyliodonium salts, novel regioselective alkynylation of benzotriazole at the 2 position was observed.

Expanding family of π-conjugated trinuclear dithiolenes: the cases of group 8 (Ru(II)) and 10 (Ni(II) and Pt(II)) metals.

New π-conjugated trinuclear dithiolenes with group 8 (6, Ru(II)) and 10 (7 and 8, Ni(II) and Pt(II)) metals were synthesized. Compounds 6 and 7 exhibited intense electronic communication through the phenylene bridge among the three dithiolene moieties during oxidation of the metalladithiolene rings, which has not been confirmed in the analogous family of group 9 metals, 1-5. Compound 8 exhibited an intense absorption band across the visible and near-IR regions, which was assigned as a charge transfer to the diimine and was red-shifted and broadened compared to the corresponding band of the mononuclear complex.