Photophysical Properties and Application of Transition Metal Complexes Having Arylborane Units

In this review, we overview the recent research trends on the photophysical properties and its application of metal complexes having arylborane charge transfer unit(s). The vacant p-orbital on the boron atom (p(B)) in a triarylborane derivative plays important roles in determining the electronic structure and the photophysical properties of the derivative. Recent studies on the spectroscopic and excited-state properties of arylborane compounds indicated that the characteristic absorption and emission bands were ascribed essentially to the charge transfer (CT) transition between the p -orbital of the aryl group ( p (aryl)) and p(B) : p (aryl)-p(B) CT. By utilizing such characteristics of triarylborane derivatives, new and novel approaches toward tuning of the redox, spectroscopic, and excited-state properties of metal complexes have been explored through combining the p (aryl)-p(B) CT interaction in a triarylborane derivative with the metal-to-ligand charge transfer (MLCT), intramolecular charge transfer (ILCT) state and electron or energy transfer of a metal complex.