Shigehiro Yamaguchi

Incorporation of main group elements into the π-conjugated frameworks is a sophisticated strategy to alter the fundamental nature of the parent conjugated π-systems, giving rise to attractive electronic and photophysical properties that are otherwise inaccessible with classic carbon- or metal-based materials. Out of all π-conjugated heterocycles, those that are structurally constrained by tethered aryl substituents surrounding the main group center deserve a great deal of attention because not o

The boron-containing pi-conjugated systems, including tri(9-anthryl)borane (1) and tris[(10-dimesitylboryl)-9-anthryl]borane (2), have been investigated as a new type of fluoride chemosensor. Upon complexation of 1 with a fluoride ion, a significant color change from orange to colorless was observed and, in the UV-visible absorption spectra, the characteristic band of 1 at 470 nm disappeared and new bands around 360-400 nm assignable to pi-pi transitions of the anthryl moieties were observed. Th

A series of dibenzoborole derivatives with various groups such as (N,N-diphenylamino)phenyl, thienyl, and bithienyl groups at the 3,7-positions have been synthesized and their photophysical properties studied. These new pi-electron systems show significant solvatochromism in the fluorescence spectra. Thus, about 100-140 nm blue shifts in the emission maxima and 20-30-fold increments in the quantum yields are observed upon changing the solvent from THF to DMF. Similar fluorescence changes are obs

Abstract For the molecular design of new π-electron materials, the incorporation of main group elements into the π-conjugated frameworks is a powerful approach to modifying the nature of the parent π-conjugated systems. In particular, the group 13 boron is of interest, since the boron element has several characteristic features, such as an effective orbital interaction with the π-conjugated frameworks through the vacant p-orbital (i.e., p π -π* conjugation), high Lewis acidity, and trigonal plan

Synthesis, properties, and application of new σ- and π-electron systems consisting of the silole rings are described. A series of 2,5- and 1,1-difunctionalized siloles have been prepared based on the intramolecular reductive cyclization of diethynylsilanes. Starting from these functionalized siloles, oligo(2,5-silole)s and oligo(1,1-silole)s have been synthesized as model compounds for poly(2,5-silole)s and poly(1,1-silole)s, respectively, which are still veiled target molecules in this field. S

Abstract Various types of main group element-containing π-electron systems have been synthesized using silole, dibenzoborole, or bis-silicon-bridged stilbene as the key building units. In these π-electron systems, the orbital interaction between the main group element moiety and the π-conjugated framework, such as pπ–π* and σ*–π* conjugation, plays a crucial role in determining their characteristic electronic structures and makes them promising materials for applications in organic electronics a

BBC news: Two boron atoms have been incorporated into a carbon nanosheet by a bottom-up synthesis to give a “B-doped nanographene” (see picture) with a defined structure. The experimental and theoretical analyses revealed the important role of the two boron atoms in producing its characteristic properties, such as broad absorption bands covering the visible region and reversible redox processes. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such do

Abstract The purpose of this work is the theoretical elucidation of the origin of the unusually long UV-vis absorption maximum, λmax = 398 nm, of 3,3′,4,4′-tetraphenyl-2,2′-bisilole, which we have observed recently. Several semiempirical and ab initio calculations have been performed for some model compounds, silole and 2,2′-bisilole, in comparison with their carbon analogs, cyclopentadiene and 1,1′-bi-1,3-cyclopentadiene, respectively. The PM3 calculations indicate that the silole ring has a co

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTTri-9-anthrylborane and Its Derivatives: New Boron-Containing π-Electron Systems with Divergently Extended π-Conjugation through BoronShigehiro Yamaguchi, Seiji Akiyama, and Kohei TamaoView Author Information Institute for Chemical Research, Kyoto University Uji, Kyoto 611-0011, Japan Cite this: J. Am. Chem. Soc. 2000, 122, 26, 6335–6336Publication Date (Web):June 16, 2000Publication History Received30 December 1999Published online16 June 2000Pub

Electron-donating aryl groups were attached to electron-accepting benzophosphole skeletons. Among several derivatives thus prepared, one benzophosphole oxide was particularly interesting, as it retained high fluorescence quantum yields even in polar and protic solvents. This phosphole-based compound exhibited a drastic color change of its fluorescence spectrum as a function of the solvent polarity, while the absorption spectra remained virtually unchanged. Capitalizing on these features, this ph

A series of 2,5-diaryl-3,4-diphenylsiloles, with various mono-substituted phenyl groups, extended pi-conjugated groups, and heteroaryl groups as aryl groups at the 2,5-positions, has been prepared by a one-pot synthesis from bis(phenylethynyl)silanes based on the intramolecular reductive cyclization followed by the palladium-catalyzed cross-coupling with aryl halides. Crystal structures and chemical reactivities toward the alkaline desilylation reactions have been studied on the 2,5-bis(p-mono-s

A synthetic route to a dibenzoborole, kinetically stabilized by the 2,4,6-tri-tert-butylphenyl group, was developed, and a series of pi-extended derivatives were synthesized, which show orange-red emissions and stable electrochemical redox properties.

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTOxidative Cyclization of Bis(biaryl)acetylenes: Synthesis and Photophysics of Dibenzo[g,p]chrysene-Based Fluorescent PolymersShigehiro Yamaguchi and Timothy M. SwagerView Author Information Department of Chemistry Massachusetts Institute of Technology Cambridge, Massachusetts 02139 Cite this: J. Am. Chem. Soc. 2001, 123, 48, 12087–12088Publication Date (Web):November 8, 2001Publication History Received23 July 2001Published online8 November 2001Pu

A series of tris(phenylethynylduryl)boranes (R-C(6)H(4)-C&tbd1;C-duryl)(3)B with various substituents R have been prepared as air-stable solids owing to the steric protection of the boron atom by the three bulky duryl groups. These compounds show unique photophysical properties due to the p(pi)-pi conjugation through the p-orbital on the boron atom. In particular, a push-pull type derivative with R = NMe(2) exhibits a significant solvatochromism of fluorescence from blue to orange colors.

4,4-Difluoro-4-bora-3a,4a-diaza-s-indacenes (BODIPYs) are fascinating dyes with great potentials for various applications. To establish the design principle for the modification of the BODIPY skeleton, we now investigate the electronic impacts of the introduction of ring-fused structures. The DFT calculations revealed that while the benzene-fusing at the a bond in the BODIPY skeleton increases the HOMO level, the benzene-fusing at the b bond leads to a decreased LUMO level. Based on these result