Synthesis of n-type poly(benzotriazole)s having p-conducting and polymerizable carbazole pendants

Poly( benzotriazole)s, P(BTz)s, having an n-type benzotriazole-pi-conjugated main chain and p-type and electrochemically polymerizable carbazole (CBz) pendant groups, -(CH2)(m)-CBz (m = 12 or 6) groups, were synthesized by Ni- ( for homopolymers) and Pd-promoted ( for a copolymer) organometallic polycondensations. The copolymer between benzotriazole with the -(CH2)(12)-CBz pendant and p-phenylene was soluble in organic solvents and showed a number-average molecular weight (M-n) of 27000 in the GPC analysis. The homopolymers (m = 12, 6) were less soluble, and about half of the polymer was soluble in CHCl3 in the case of m = 12; the soluble part gave an M-n value of 4700. The polymers were photoluminescent with quantum yields of 50-70%. Cyclic voltammograms of the polymers revealed that the polymers were active in electrochemical n-doping in accord with the electron-accepting nature of the benzotriazole main chain. Application of electrochemical oxidation potential to the polymer made the polymer insoluble due to occurrence of electrochemical polymerization of the CBz unit.