High radiative efficiency based on intramolecular charge transfer in a 9,9'-bianthracene--carboranyl luminophore.

Herein, we prepared an -carborane compound (9biAT) linked to a 9,9'-bianthracene moiety at each C9-position. The compound exhibited reddish emission in solid and solution states. The solvatochromism effect and theoretical calculation results for the excited (S) state of 9biAT verified that the emission was attributed to ICT transition.

Relationship between the Molecular Geometry and the Radiative Efficiency in Naphthyl-Based Bis-Ortho-Carboranyl Luminophores.

The efficiency of intramolecular charge transfer (ICT)-based emission on π-aromatic-group-appended -carboranyl luminophores is known to be affected by structural fluctuations and molecular geometry, but investigation of this relationship has been in progress to date. In this study, four naphthyl-based bis--carboranyl compounds, in which hydrogen ( and ) or trimethysilyl groups ( and ) were appended at the -carborane cage, were synthesized and fully characterized. All the compounds barely displayed an emissive trace in solution at 298 K; however, and distinctly exhibited a dual emissive pattern in rigid states (in solution at 77 K and in films), attributed to locally excited (LE) and ICT-based emission, while and showed strong ICT-based greenish emission.

Influence of Electronic Environment on the Radiative Efficiency of 9-Phenyl-9-carbazole-Based -Carboranyl Luminophores.

The photophysical properties of carboranyl-based donor-acceptor dyads are known to be affected by the electronic environment of the carborane cage but the influence of the electronic environment of the donor moiety remains unclear. Herein, four 9-phenyl-9-carbazole-based --carboranyl compounds (, , , and ), in which an -carborane cage was appended at the C3-position of a 9-phenyl-9-carbazole moiety bearing various functional groups, were synthesized and fully characterized using multinuclear nuclear magnetic resonance spectroscopy and elemental analysis. Furthermore, the solid-state molecular structures of and were determined by X-ray diffraction crystallography.