title: Synthesis and structure-property relationships of 2,2'-bis(benzo[b]phosphole) and 2,2'-benzo[b]phosphole-benzo[b]heterole hybrid π systems.
abstract: The first comprehensive study of the synthesis and structure-property relationships of 2,2'-bis(benzo[b]phosphole)s and 2,2'-benzo[b]phosphole-benzo[b]heterole hybrid π systems is reported. 2-Bromobenzo[b]phosphole P-oxide underwent copper-assisted homocoupling (Ullmann coupling) and palladium-catalyzed cross-coupling (Stille coupling) to give new classes of benzo[b]phosphole derivatives. The benzo[b]phosphole-benzo[b]thiophene and -indole derivatives were further converted to P,X-bridged terphenylenes (X = S, N) by a palladium-catalyzed oxidative cycloaddition reaction with 4-octyne through the C(β)-H activation. X-ray analyses of three compounds showed that the benzo[b]phosphole-benzo[b]heterole derivatives have coplanar π planes as a result of the effective conjugation through inter-ring C-C bonds. The π-π* transition energies and redox potentials of the cis and trans isomers of bis(benzo[b]phosphole) P-oxide are very close to each other, suggesting that their optical and electrochemical properties are little affected by the relative stereochemistry at the two phosphorus atoms. The optical properties of the benzo[b]phosphole-benzo[b]heterole hybrids are highly dependent on the benzo[b]heterole subunits. Steady-state UV/Vis absorption/fluorescence spectroscopy, fluorescence lifetime measurements, and theoretical calculations of the non-fused and acetylene-fused benzo[b]phosphole-benzo[b]heterole π systems revealed that their emissive excited states consist of two different conformers in rapid equilibrium.
authors.affiliation: Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Hayashi
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Matano
authors.forename: Kayo
authors.initials: K
authors.lastname: Suda
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Kimura
authors.forename: Yoshihide
authors.initials: Y
authors.lastname: Nakao
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Imahori
mesh_terms: D002384:Catalysis; D018360:Crystallography, X-Ray; D004563:Electrochemistry; D015394:Molecular Structure; D009943:Organophosphorus Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010084:Oxidation-Reduction; D010165:Palladium / Q000737:chemistry*; D013050:Spectrometry, Fluorescence
chemical_list: C581178:2,2'-bis(benzo(b)phosphole); D009943:Organophosphorus Compounds; D010165:Palladium