π-conjugated organoboron polymers via the vacant p-orbital of the boron atom

A decade has passed since organoboron pi-conjugated systems highly extended through the empty p-orbital of the boron atom emerged as a new class of pi-conjugated materials. Making use of convenient hydroboration polymerization, a variety of pi-conjugated organoboron polymers exhibiting fluorescence emission, n-type electrochemical activity, electrical conductivity, third order non linear optical property, anion sensing ability is easily prepared. The organoboron pi-conjugated polymers having highly bulky substituent on the boron atom shows high stability under air and moisture and therefore, potentially useful for versatile applications. The design of electron deficient organoboron pi-systems led to observation of unique photophysical behavior such as extraordinary high third order non linear optical susceptibility, facilitation of p pi-d pi* transition, intramolecular charge transfer, unusually activated sigma-pi conjugative interaction and so forth. In addition to boration polymerization methods, polycondensation using di-Grignard reagent, Sonogashira type polycondensation, polycondensation via tin-boron exchange are useful for synthesis of pi-conjugated organoboron polymers.