Akihito Konishi

A teranthene derivative has been successfully isolated in a crystalline form for the first time. Geometrical considerations and physical property investigations indicate that the molecule possesses prominent biradical character in the ground state.

The characteristics of the edge state, which is a peculiar magnetic state in zigzag-edged graphene nanoribbons (ZGNRs) that originates from electron-electron correlation in an edge-localized π-state, are investigated by preparing and characterizing quarteranthene molecules. The molecular geometry that was determined from the X-ray analysis is consistent with a zigzag-edge-localized structure of unpaired electrons. The localized electrons are responsible for the peculiar magnetic (room-temperatur

Abstract Azulene 1, pentalene 2, and heptalene 3 are classical nonalternant hydrocarbons. Their fascinating π-frameworks, consecutive arrangements of odd-membered carbocycles, have engaged chemists’ attention for some time. In this review, we describe the salient revivals of these nonalternant hydrocarbons that are incorporated into polycyclic π-systems. Historical landmarks, recent studies, and fundamental properties, as well as potential applications to functional organic materials, are docume

A nonbenzenoid hydrocarbon, difluoreno[1,9,8- alkj:1',9',8'- gfed]heptalene 1, is synthesized. Experimental and theoretical investigations demonstrate that the planar and symmetric heptalene core within 1 effectively induces the antiaromatic and open-shell character. These properties are not shared by bisanthene 2, a benzenoid isomer of 1.

Mesityl derivatives of the unknown dibenzopentalene isomer dibenzo[a,f]pentalene were synthesized. The molecular geometry and physical properties of dibenzo[a,f]pentalene were investigated. Dibenzo[a,f]pentalene combines a large antiaromatic and appreciable singlet open-shell character, properties not shared by well-known isomer dibenzo[a,e]pentalene.

Understanding the structure-property relationships in antiaromatic molecules is crucial for controlling their electronic properties and designing new organic optoelectronic materials. Dibenzo[ a, f]pentalene, a structural isomer of dibenzopentalene, displays open-shell and antiaromatic character harmonization, which is not shared by the well-known isomer, dibenzo[ a, e]pentalene. The next questions of interest concern the topological effects of the π-extension on the harmonization of the open-sh

Abstract The improved Scholl reaction allows for the direct cyclization of anthracene oligomers to give bisanthene, teranthene, and quateranthene. Furthermore, a variety of π-expanded bisanthenes are obtained by the Diels–Alder cycloaddition of bisanthene with several arynes. These reactions would allow us to synthesize various size- and shape-controlled polyperiacenes.

Polycyclic aromatic hydrocarbons (PAHs) that incorporate either heptagons or pentagons consist of non-planar molecular structures with unusual optoelectronic properties, and the design of a relatively simple and efficient method to construct these highly fused π-conjugated systems with odd-membered rings is in high demand. This work describes the use of silver(I) cations to promote the efficient synthesis of azulene-embedded PAH 2, which is a structural isomer of tribenzo[fg,ij,rst]pentaphene 3,

Abstract New π-extended pentalene derivatives bearing two thiophene rings are synthesized from 3-bromo-4-ethynylthiopenes as stable orange crystals by using a nickel complex. The observed electronic properties and molecular structure clearly indicate low contribution of the pentalene π system as predicted by the TD-DFT calculations.

Abstract The chemistry of nonalternant hydrocarbons has recently experienced a considerable resurgence. As the relationship between naphthalene and azulene shows, an important design concept for a nonalternant framework is to replace the two hexagons of an alternant system with a pentagon and heptagon pair. The pursuit of the nonalternant isomers of pyrene, which has seven possible nonalternant isomers, has been the most significant related project. Through enormous dedication by many pioneering

Abstract The edge state, which is a peculiar magnetic state in zigzag-edged graphene nanoribbons (ZGNRs) originating from an electron–electron correlation in an edge-localized π-state, has promising applications for magnetic and spintronics devices and has attracted much attention of physicists, chemists, and engineers. For deeper understanding of the edge state, precise fabrication of edge structures in ZGNRs has been highly demanded. We focus on anthenes, which are peri -condensed anthracenes

Monomeric cage-shaped aluminum aryl oxides <b>1</b>Al were synthesized using tripodal triphenolic ligands. The Lewis acidity and catalytic activity of the obtained <b>1</b>Al·py were investigated. The Lewis acidity of <b>1</b>Al·py originates from the flexible change in the coordination number of the aluminum center, allowing the catalytic <i>O</i>-glycosylation to occur with a high efficiency and an unusual stereoselectivity.

The synthesis and isolation of atrane-type molecules 1E⁺ (E=Si, Ge, or Sn) having a cationic group 14 elemental center are reported. The cations 1E⁺ act as hard and soft Lewis superacids, which readily interact with various hard and soft Lewis basic substrates. The rigid atrane framework stabilizes the localized positive charge on the elemental center and assists the formation of the well-defined highly coordinated states of 1E⁺ . The cations were applied to the