La fundación de la Madrasa al-Adāb por la Asociación de ulemas musulmanes argelinos en la ciudad de Hennaya (Tremecén) en 1950

A biphenyl-fused BODIPY was synthesized through a facile oxidative cyclization of peripheral aryl-substituents at the β-position of the BODIPY unit. The extended π-system of the fused BODIPY induces near-infrared (NIR) absorption and strong π–π interactions in the solid state. These features are beneficial for the application of the dye as a functional material. The biphenyl-fused BODIPY dye was demonstrated to exhibit photocurrent conversion ability on the basis of its <i>n</i>-type semiconducting property

A Radical Anion of Structurally Constrained Triphenylborane

Chemical reduction of the structurally constrained triphenylborane <b>1</b> with K produced a radical anion. EPR analysis demonstrated the delocalization of the unpaired electron spin density over the entire π skeleton to a greater extent than is the case for a nonconstrained Ph₃B radical anion. DFT calculations indicated that the coplanarization of the benzene rings with the boron plane and the shortening of the B–C bond lengths by the structural constraint are responsible for the spin delocalization. The geometry optimization also suggested a bowl-shaped conformation as a viable local minimum structure in addition to the planar conformation. X-ray crystal structure analysis indeed revealed the nonplanar structure of the radical anion <b>1</b>^{<b>•–</b>}

A Pentacoordinate Boron-Containing π‑Electron System with Cl–B–Cl Three-Center Four-Electron Bonds

Tricoordinate boron-containing π-electron systems are an attractive class of compounds with intense fluorescence and strong electron-accepting properties. However, the impact of pentacoordination of the boron atoms on their properties has not been determined. We now disclose a <i>B</i>,<i>B</i>′-bis­(1,8-dichloro-9-anthryl)-substituted 9,10-dihydro-9,10-diboraanthracene as a new pentacoordinate organoboron compound. In this skeleton, with the aid of the orthogonal arrangement of the anthryl substituent, the B and Cl atoms can form a three-center four-electron (3c–4e) Cl–B–Cl bond. The pentacoordination of the boron atom significantly perturbs the electronic structure and thereby the photophysical and electrochemical properties

Photodissociation of B–N Lewis Adducts: A Partially Fused Trinaphthylborane with Dual Fluorescence

The synthesis of a planarized trinaphthylborane with partially fused structure is presented. This compound shows not only high chemical and thermal stability but also sufficient Lewis acidity to form Lewis adducts with pyridine derivatives in solution. The B–N Lewis adducts exhibit unprecedented photodissociation behavior in the excited state, reminiscent of the photogeneration of carbenium ions from triarylmethane leuco dyes. Consequently, these B–N Lewis adducts exhibit dual fluorescence emission arising from the initial tetracoordinate B–N adducts and the photodissociated tricoordinate boranes

Polycyclic π-Electron System with Boron at Its Center

We disclose a new planarized triarylborane in which the tri-coordinated boron atom is embedded in a fully fused polycyclic π-conjugated skeleton. The compound shows high stability toward oxygen, water, and silica gel, despite the absence of steric protection around the B atom. Reflecting the electron-donating character of the π-skeleton and the electron-accepting character of the B atom, this compound shows broad absorption bands that cover the entire visible region and a fluorescence in the visible/near-IR region. In addition, this compound shows dramatic property changes upon formation of a tetra-coordinated borate, such as thermochromic behavior in the presence of pyridine

Polycyclic π-Electron System with Boron at Its Center

We disclose a new planarized triarylborane in which the tri-coordinated boron atom is embedded in a fully fused polycyclic π-conjugated skeleton. The compound shows high stability toward oxygen, water, and silica gel, despite the absence of steric protection around the B atom. Reflecting the electron-donating character of the π-skeleton and the electron-accepting character of the B atom, this compound shows broad absorption bands that cover the entire visible region and a fluorescence in the visible/near-IR region. In addition, this compound shows dramatic property changes upon formation of a tetra-coordinated borate, such as thermochromic behavior in the presence of pyridine

Polycyclic π-Electron System with Boron at Its Center

We disclose a new planarized triarylborane in which the tri-coordinated boron atom is embedded in a fully fused polycyclic π-conjugated skeleton. The compound shows high stability toward oxygen, water, and silica gel, despite the absence of steric protection around the B atom. Reflecting the electron-donating character of the π-skeleton and the electron-accepting character of the B atom, this compound shows broad absorption bands that cover the entire visible region and a fluorescence in the visible/near-IR region. In addition, this compound shows dramatic property changes upon formation of a tetra-coordinated borate, such as thermochromic behavior in the presence of pyridine

Heterotriangulenes π‑Expanded at Bridging Positions

A series of nitrogen-containing heterotriangulenes expanded at the bridging positions has been synthesized. Among them, a dibenzo­[<i>c,g</i>]­fluorenylidene-substituted derivative has a highly twisted conformation for the overcrowded alkene moieties, which impart a highly electron-accepting character to the electron-donating heterotriangulene skeleton and thereby an NIR absorption as well as multiredox properties with a low reduction potential

Polycyclic π-Electron System with Boron at Its Center

We disclose a new planarized triarylborane in which the tri-coordinated boron atom is embedded in a fully fused polycyclic π-conjugated skeleton. The compound shows high stability toward oxygen, water, and silica gel, despite the absence of steric protection around the B atom. Reflecting the electron-donating character of the π-skeleton and the electron-accepting character of the B atom, this compound shows broad absorption bands that cover the entire visible region and a fluorescence in the visible/near-IR region. In addition, this compound shows dramatic property changes upon formation of a tetra-coordinated borate, such as thermochromic behavior in the presence of pyridine

Heterotriangulenes π‑Expanded at Bridging Positions

A series of nitrogen-containing heterotriangulenes expanded at the bridging positions has been synthesized. Among them, a dibenzo­[<i>c,g</i>]­fluorenylidene-substituted derivative has a highly twisted conformation for the overcrowded alkene moieties, which impart a highly electron-accepting character to the electron-donating heterotriangulene skeleton and thereby an NIR absorption as well as multiredox properties with a low reduction potential