Aiko Fukazawa

Ladder pi-conjugated compounds, which have fully ring-fused polycyclic skeletons, are an important class of materials possessing significant potentials for application in organic electronics. The incorporation of main-group elements, such as B, Si, P, S, and Se, into the ladder skeletons as bridging moieties is a powerful strategy to endow unusual electronic structures as well as suitable molecular arrangements in the solid state, giving rise to attractive photophysical and electronic properties

A rung up: A polar and rigid stilbene with phosphonium and borate bridging moieties was synthesized by the spontaneous cyclization of a boryl- and phosphanyl-substituted diphenylacetylene (see picture). Various extended ladder π-conjugated molecules can be synthesized in this manner. The zwitterionic moiety significantly modulates the electronic structure, thus leading to attractive fluorescence and redox properties.

Bis-phosphoryl-bridged stilbenes have been synthesized using an intramolecular cascade cyclization. They show intense blue fluorescences at longer wavelengths with higher quantum yields compared to those of the known element-bridged stilbenes. In addition, they have much lower reduction potentials due to the inductive effect of phosphoryl groups. The incorporation of the phosphoryl moiety is an effective way for the construction of highly electron-accepting pi-conjugated systems.

The highly Lewis acidic perfluoropentaphenylborole forms a stable, isolable adduct with the weak Lewis base carbon monoxide. A similar adduct with the unfluorinated borole is observed at low temperature, but this adduct undergoes reaction involving insertion into the B–C bonds due to the greater nucleophilicity of the α-carbons. Together these observations provide concrete chemical evidence for long held presumptions regarding the observed reactivity of organoboranes with carbon monoxide.

The silicon analogues of the oligo(p-phenylenevinylene)s (Si-OPVs) with highly planar structures have been synthesized using a newly developed ligand, the 1,1,3,3,5,5,7,7-octaethyl-s-hydrindacen-4-yl (Eind) group. Their X-ray crystal structures and spectroscopic data demonstrate that the π-conjugation effectively extends over the Si-OPV framework. Notably, tetrasiladistyrylbenzene exhibits an orange fluorescence even at room temperature both in solution and in the solid state, which is attributa

Abstract The intramolecular trans ‐halophosphanylation of 2‐(aminophosphanyl)phenylacetylenes mediated by PBr 3 followed by the oxidation with H 2 O 2 , produces 3‐bromobenzo[ b ]phosphole oxide derivatives. This cyclization is also used for the synthesis of a 3‐iodo derivative by conducting the reaction in the presence of LiI. Based on this synthetic method, various benzophosphole‐containing π‐conjugated compounds, including a phosphoryl and methylene‐bridged stilbene 10 , 2,3,6,7‐tetraphenylbe

Eine Sprosse rauf: Ein polares und starres Stilben mit Phosphonium- und Boratbrücke entstand bei der spontanen Cyclisierung eines boryl- und phosphanylsubstituierten Diphenylacetylens (siehe Bild). Eine Vielzahl leiterartiger, ausgedehnt π-konjugierter Moleküle ist auf diese Art zugänglich. Die zwitterionische Einheit moduliert die elektronische Struktur merklich, was attraktive Fluoreszenz- und Redoxeigenschaften zur Folge hat. Supporting information for this article is available on the WWW und

The perfect all-anti-octasilane composed of two bicyclic trisilane units with trimethylsilyl groups at the termini has been synthesized. Its X-ray crystal structure and spectroscopic data demonstrate the effective sigma-delocalization over the silicon framework, which is a definitive difference from the unconstrained n-Si8Me18.

The synthesis and properties of the phosphonium- and borate-bridged stilbenes are reported. The zwitterionic ladder stilbenes were synthesized by the intramolecular cascade cyclization from the phosphanyl- and boryl-substituted diphenylacetylenes 1. The study of the substituent effects of the phosphanyl and boryl groups revealed the significant dependence of the reactivity on both the nucleophilicity of the phosphanyl group and the electrophilicity of the boryl group. Theoretical calculations in

A series of 2,3,4,5-tetraphenylphosphole oxides with various aryl groups on the phosphorus atoms were synthesized and their fluorescence properties in the crystalline state were investigated. Some of these compounds showed an intense fluorescence with the quantum yields of 0.75–0.91. These intense emissions are attributable not only to the restricted rotation of the peripheral phenyl rings, but also to the long intermolecular distances between the adjacent molecules in the crystal packing.

Over the past two decades, the charge carrier mobility of π-conjugated polymers has vastly improved. This has been mostly achieved by increasing the π–π stacking ability of the polymers through advanced molecular design, thereby improving “interchain” charge carrier transport. However, the rational design of π-conjugated polymers for improving “intrachain” charge carrier transport along the backbone still remains a formidable challenge. Here, we show the synthesis of a new π-conjugated polymer b

The transannular cyclization of dehydroannulenes bearing several alkyne moieties in close proximity is a powerful synthetic method for producing polycyclic aromatic hydrocarbons. We report that the reactivity can be switched by the aromaticity of the ring skeletons fused with the dehydroannulene core. Thus, while thiophene-fused bisdehydro[12]annulene 1 was handled as a stable compound in the air at room temperature, the oxidation with m-chloroperbenzoic acid from the aromatic thiophene rings to

Abstract 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

Dithieno[a,e]penalenes (DTPs) with various substituents were synthesized as a class of antiaromatic compounds. Annulation of thiophene rings imparts the pentalene moiety with high thermal stability even without bulky substituents, while retaining antiaromaticity. The higher magnitude of antiaromaticity in DTPs, in addition to the differences in the electronic structures of the fused aromatic rings, resulted in a narrower HOMO-LUMO gap than that of the corresponding dibenzo[a,e]pentalene analog,

A bridge worth crossing: Various phosphonium- and borate-bridged bis(arylethenyl)benzenes were synthesized. The large two-photon absorption (TPA) cross sections in these zwitterionic ladder π-electron systems revealed that the introduction of zwitterionic bridges in the coplanar π-conjugated framework is a powerful strategy for designing excellent TPA materials.