Tomohiro AGOU

Azaborines and ladder- type azaborines bearing various functional groups can be synthesized starting from common dibromo derivative intermediates, and among several substituents, the carbazol- 9- yl group was shown to enhance the photo- luminescence quantum yield of the azaborines up to a value of unity.

Ladder-type pi-conjugated molecules bearing heteraborin (azaborine or thiaborin) units were synthesized, and X-ray crystallographic analysis of pentacene-type molecules showed that these molecules have rigid and planar structures. UV-visible spectroscopy and theoretical calculations revealed the enhancement of electronic interaction between heteraborin units, the decrease in HOMO-LUMO energy gaps, and the strong effect of the bridging main-group elements (nitrogen or sulfur) on the electronic states. The ladder-type molecules emitted strong fluorescence both in solution and in the solid state, and the emission-band shapes were different from each other, indicating the existence of intermolecular interactions in the solid state. Complex formation of the ladder molecules with fluoride ion was monitored by UV-visible spectroscopy, which revealed that the Lewis acidity of these molecules can be controlled by the elongation of it systems and the change of the bridging main-group elements.

The low sigma-donating ability of 9-phosphatriptycene 1 was revealed by cyclic voltammetry and theoretical calculations. The tungsten complex of 1 was synthesized and the IR and NMR spectroscopic data of the complex also suggested the low sigma-donating ability of 1. 1 was shown to be effective as a ligand in the palladium-catalyzed reactions, the Stille coupling and the Heck reaction.

Novel 9-phosphatriptycenes were synthesized by utilizing ortho-lithiation of a triarylphosphine oxide as a key step. The structural analysis of the 9-phosphatriptycene oxide revealed its highly distorted structure around the phosphorus atom, which is consistent with the up-field shift in the P-31 NMR spectrum. The 9-phosphatriptycene and its chalcogenides were synthesized by ordinary methods, and the spectral comparisons of these chalcogenides indicated the large s-character of the lone-pair orbital or the phosphorus-chalcogen sigma bonds of those species. The 9-phosphatriptycene oxide was reacted with lithium naphthalenide to give the ring-opened products. (C) 2004 Wiley Periodicals, Inc.

A novel synthetic route to a 9-phosphatriptycene was developed by utilizing ortho-lithiation of a triarylphosphine oxide as a key step. Systematic comparisons of the NMR spectra of 9-phosphatriptycene derivatives indicated the large s character of the lone pair orbital or the phosphorus-chalcogen bonds of the 9-phosphatriptycene derivatives.