Yoshiaki Shoji

Arylboronic esters can be used as versatile reagents in organic synthesis, as represented by Suzuki-Miyaura cross-coupling. Here we report a serendipitous finding that simple arylboronic esters are phosphorescent in the solid state at room temperature with a lifetime on the order of several seconds. The phosphorescence properties of arylboronic esters are remarkable in light of the general notion that phosphorescent organic molecules require heavy atoms and/or carbonyl groups for the efficient g

Higher fullerenes (>/=C76) were selectively extracted from a fullerene mixture obtained from a combustion-based industrial production source by cyclic dimers of beta-unsubstituted porphyrin zinc complexes 2C5-2C7 with C5-C7 alkylene spacers as host molecules. Results of single extraction of the fullerene mixture with 2C5-2C7 together with a beta-substituted analogue of 2C6 (1C6) and spectroscopic titration of 2C6 and 1C6 with C60, C70, and C96 indicated that the host selectivity toward higher fu

Highly oriented, domain-boundary-free organic thin films could find use in various high-performance organic materials and devices. However, even with state-of-the-art supramolecular chemistry, it is difficult to construct organic thin films with structural integrity in a size regime beyond the micrometer length scale. We show that a space-filling design, relying on the two-dimensional (2D) nested hexagonal packing of a particular type of triptycene, enables the formation of large-area molecular

C-C bond coupling reactions illustrate the wealth of organic transformations, which are usually mediated by organotransition metal complexes. Here, we show that a borafluorene with a B-Cl moiety can mediate sequential alkyne insertion (1,2-carboboration) and deborylation/Csp(2)-Csp(2) coupling reactions, leading to aromatic molecules. The first step, which affords a borepin derivative, proceeds very efficiently between the borafluorene and various alkynes by simply mixing these two components. T

Diborane(6) as a H-bridged dimer of monoborane can be converted cleanly by two-electron reduction into diborane(6) dianion, which is isoelectronic with ethane, through B-B σ-bond formation when each boron atom has a bulky ligand on it. The existence of the B-B σ bond is supported by the X-ray molecular structure [B-B bond length of 1.924(3) Å], NMR studies, magnetic susceptibility measurements, and DFT calculations. Stepwise hydride abstraction reactions of the diborane(6) dianion produce the co

In contrast to the common multiple bonding between carbon atoms, multiply bonded boron compounds have still been a synthetic challenge due to the electron deficiency of boron. We now report that a stable doubly hydrogen-bridged diborane(4), EindB(mu-H)(2)BEind, is produced by the two-electron oxidation of a hydrogen-substituted diborane(4) dianion [Li(+)(thf)](2)[Eind(H)BB(H)Eind](2-), where Eind denotes the 1,1,3,3,5,5,7,7-octaethyl-s-hydrindacen-4-yl. The X-ray crystallography reveals a short

Upon inclusion complexation with a racemic mixture of chiral fullerene C76 ((+/-)-C76), a novel cyclic host (1Rh) composed of a chiral N-methylporphyrin (PNMe) and a methylrhodium porphyrin (PRh) exhibited at 20 degrees C a 1H NMR spectral profile with diastereoisomerically split signals due to the NH group of PNMe. In contrast, because of a faster guest exchange dynamics, metal-free reference 12H, under identical conditions, did not show any signature of such diastereoisomeric splitting. Owing

Optical resolution of nonsubstituted chiral fullerenes such as C(76) is one of the most challenging subjects in host-guest chemistry. The novel cyclic host 1(2H), which bears a meso-diaryl-beta-octaethylporphyrin (P(2H)) unit on one side and its chiral N-2-acetoxyethyl derivative (P(N-EtOAc)) on the other, traps C(76) enantioselectively in its cavity and furnishes 7% enantiomeric excess in a single extraction. Control experiments using reference hosts indicated the importance of the high pi-basi

Unlike planar aromatic compounds, bowl-shaped sumanene, which has concave and convex faces with different electrostatic potentials, tends to form a one-dimensional columnar assembly without causing slip-stacking in the crystal. Here we report the first successful synthesis of liquid-crystalline (LC) sumanenes, which was brought about by the incorporation of six thioalkyl groups (R = SC₆H₁₃ or SC₁₂H₂₅) into the aromatic part of sumanene. In contrast to

Abstract The first isolable diborane(4) containing terminal B–H bonds, protected by the bulky 1,1,7,7-tetramethyl-3,3,5,5-tetrapropyl-s-hydrindacen-4-yl (MPind) groups, was synthesized as air- and moisture-sensitive colorless crystals. The structure and bonding nature of this H-terminal diborane(4), characterized by X-ray crystallography, NMR studies, and DFT calculations, were compared to those of the previously reported isomer, a doubly H-bridged butterfly-shaped diborane(4) bearing the less b

Borinium ions, that is, two-coordinate boron cations, are the most electron-deficient isolable boron compounds. As borinium ions have only four formal valence electrons on boron, they should show a strong tendency to accept electron pairs on the boron atom to fill its valence shell. Thus chemical reactions of borinium ions are expected to give products in which the coordination number of boron is increased from two to three or four. However, contrary to this expectation, we found that the dimesi

The first crystallographic and electron density distribution analyses of a thioaroyl cation unveil its true structural perspective; this chemical species can be mainly expressed as the combination of the thioketene form (II) and sulfonium form (III) with a C≡S(+) triple bond character.

We recently reported a new one-pot transformation of alkynes into 9,10-diarylphenanthrene derivatives, which proceeds through efficient catalyst-free 1,2-carboboration of alkynes with 9-chloro-9-borafluorene (1_Cl ), which yields a chlorodibenzoborepin, followed by oxidative deborylation/C-C coupling of the resultant chlorodibenzoborepin. Herein, based on new experimental observations for the catalyst-free 1,2-carboboration by using diphenylacetylenes and 1_Br or 1<sub>OTf</s

Replacement of the carbon-carbon bonds of antiaromatic compounds with polar boron-nitrogen bonds often provides isoelectronic BN compounds with excellent thermodynamic stability and interesting photophysical properties. By this element-substitution strategy, we synthesized a new B₄ N₄ -heteropentalene derivative, 1, which is fully substituted with mesityl groups. Owing to kinetic protection by the sterically bulky substituents, 1 is remarkably stable toward air and even wat