Thiophene-fused ladder boroles with high antiaromaticity.

A series of polycyclic thiophene-fused boroles were synthesized on the basis of stepwise substitution reactions from thienylboronic ester precursors. In these ladder-type π-conjugated systems, the thiophene-fused structure enhances the antiaromaticity of the borole ring. This trend is opposite to the conventional understanding that the arene-fused structure decreases the antiaromaticity of the 4π-electron ring skeletons.

Intense solid-state blue emission with a small Stokes' shift: pi-stacking protection of the diphenylanthracene skeleton.

Intense blue emissions with a small Stokes' shift both in solution and in the solid state were attained by introducing (pentafluorophenyl)dimethylsilyl groups to a 9,10-diphenylanthracene skeleton as the pi-stacking tethers.

Disilylphenylene and tetrasilylphenylene as a new building unit for highly fluorescent poly(aryleneethynylene)s.

We report the synthesis and photophysical properties of poly(aryleneethynylene)s (PAEs) containing disilyl- or tetrasilyl-substituted phenylene as the key building unit. The fluorescence spectra of one of the PAEs, consisting of the diethynylbis(trimethylsilyl)phenylene and fluorenylene units, shows an intense blue emission with the maximum at 428 nm. The absolute quantum yield (Phi(F)) and the fluorescence lifetime (tau(s)) are 0.