Hideki Sakurai

Organic electroluminescence of silole-incorporated polysilane

Abstract We have examined the electroluminescent (EL) device utilizing a new type of polysilane that incorporates siloles with a high electron affinity, poly(2′,3′,4′,5′-tetraphenyl-1′-silacyclopenta-2′,4′-diene-1′,1′-ylidene-1,1,2,2,3,3,4,4-octamethyltetrasilanylene) (PDMS-S). PDMS-S based single-layer EL device exhibited blue emission with a peak at 488xa0nm and better electrical properties compared to the device using poly(methylphenylsilane) (PMPS) without silole rings. The maximum external quantum efficiency of the device with PDMS-S was 0.001% and the maximum luminance reached was 5xa0cd/m2 at 22xa0V. The hole-transporting properties of PDMS-S were almost equal to that of PMPS from the hole-mobility with the standard time-of-flight technique and the current–voltage characteristics of double-layer EL device which comprised of PDMS-S as a hole-transporting layer and tris (8-quinolinolato) aluminum (III) complex as an electron-transporting emitting layer. It is clear from these results of the improvement in the single-layer device with PDMS-S and the hole-transporting properties that the electron-transporting property of PDMS-S with silole rings is higher than that of PMPS.

Novel π-electron systems derived from silicon-containing macrocyclic polyacetylenes

Disilmethylene bridged cyclic Iriacetylene and tetraacetylene are prepared and subjected the transition metal complex mediated reactions. In particular, the reaction with (cyc1opentadienyl)txicarbonylmanganese gave a variety of cross-conjugated systems such as lulvene, dimethylenecyclobutene, trimethylenecyclopenkne and radialene. Structures and reactions of these interesting x-electron systems are described. Dianions derived from these systems are also discussed briefly.

Alkoxide initiation of anionic polymerization of masked disilenes to polysilanes

Abstract The polymerization of masked disilenes initiated by potassium alkoxides in the presence of cryptand[2.2.2] in benzene proceeded in a living manner, especially when using potassium (−)-menthoxide. The molecular weights of the polysilanes thus obtained were in good agreement with the calculated values.

Encapsulation of polysilane into shell cross-linked micelles

The cross-linking reaction of the poly(methacrylic acid) block of poly(1,1-dimethyl-2,2-dihexyldisilene)-b-poly(methacrylic acid) with 1,10-diaza-4,7-dioxadecane and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride afforded the first shell cross-linked micelles of polysilane.

Phanes bridged by group 14 heavy elements

Publisher Summary This chapter presents the chemistry of phanes bridged by group 14 heavy elements. The degree of through-bond interaction in [2.2]paracyclophane 12 bridged by two Si–Si bonds is the greatest among the series of the cyclophanes bridged by Group 14 elements. Prior to the studies on phanes, a new ring system, 3,4,7,8-tetrasilacycloocta-1,5-diyne, composed of two Si–Si σ and two C≡C π bonds is studied. The Various types of phanes have been prepared and structures and reactions have been investigated in detail. In all the [2.2]paracyclophanes, the bridging bonds are somewhat elongated from the normal bond lengths, and the benzene rings are distorted into boat conformations. [2.2]metacyclophane (2), relative conformations of two aromatic rings in [2.2](2,5)heterophanes have been studied in detail by NMR. [2.2]Paracyclophanes bridged by Group 14 heavy elements try to keep interplanar distances constant to the value for graphite, regardless of any increase in the bridging bond lengths.

Polarized electroluminescence from a uniaxially oriented polysilane thin film

A novel polysilane, poly[(p-butoxyphenyl)phenylsilane] (PBPPS) has been synthesized and employed as an emissive layer of an organic electroluminescence (EL) device. PBPPS was spin-coated onto a uniaxially oriented poly(diethylsilane) (PDES) ultrathin film prepared by the friction-transfer method. We observed polarized, near-ultraviolet (UV) EL with its dichroic ratio of 2 from the polysilane-based multilayered EL device. Polarization direction was found to be identical with the drawing direction of the friction-transfer process for the PDES film, indicating that PBPPS in the emissive layer was aligned parallel to the uniaxial orientation of PDES. A depolarized, broad visible band appeared in the EL spectrum, which was absent in photoluminescence of PBPPS or PDES films. Origins of near-UV and visible EL components are discussed.

Synthesis and Characterization of the Dilithium Salt of the Octasilyl[4]radialene Dianion: Evidence for a Lithium Walk on the Eight-Center, Ten-Electron π-Electron System

A highly symmetric structure is displayed in toluene by 1, which was obtained by reduction of octasilyl[4]radialene with lithium in THF. The two Li+ ions of 1 are not fixed to the π-electron system in toluene, but are fluxional, giving rise to a bis-contact ion pair. In a solvating medium such as THF, one of the Li+ ions dissociates in such a way that 1 exists as a contact ion pair and a solvent-separated ion pair.

Synthesis of Polysilanes by New Procedures: Part 1 Ring-Opening Polymerisations and the Polymerisation of Masked Disilenes

Polysilanes [1] have been widely investigated in recent decades because of their potential use in the field of materials science. Applications of polysilanes in several new technology areas, in particular as SiC precursors, microlithography, photoinitiators, and reprography are indicated and these applications show that polysilanes are promising as advanced materials for the high technologies of the next generation. However, there are still several problems to be solved for further development of the chemistry and physics of polysilanes. One such problem concerns the limited methods available for the synthesis polysilanes.

Conformational and orientational behavior of functional polysilanes at the air/water interface

Abstract Novel functional polysilane homopolymers bearing ethereal groups were prepared by Wurtz coupling method. The polysilane monolayers demonstrated a unique chromic effect induced by a specific conformational and orientational change of polymer backbones at the air/water interface.

Novel surface-mediated chromism of polysilane at the air/water interface

Abstract A novel ethereal group-substituted polysilane with an ordered structure exhibits an unusual chromism induced by the hydrophilic nature of the substrate surface. Compression-induced chromism and the in-plane orientation of the polysilane monolayer were also observed at the air/water interface.