Synthesis of electroactive hydrazones derived from carbazolyl-based 2-propenals for optoelectronics

Herein, we report the synthesis of 2,3-unsaturated carbazolyl and 3,3′-bicarbazolyl aldehydes by a Heck coupling methodology and the further condensation of these aldehydes with N-methyl-N-phenylhydrazine and N,N-diphenylhydrazine, resulting in mono- and dihydrazones that act as effective hole transporting materials. The thermal, optical and photophysical properties of the newly synthesized organic electroactive derivatives have been investigated. Room temperature hole-drift mobility values ranged from 10−4 to 10−3 cm2/V s in strong electric fields. The ionization potentials (Ip) of the investigated compounds were very close and ranged from 5.15 to 5.28 eV, which can be attributed to a very weak conjugation of the carbazole segments of the 3,3′-bicarbazolyl moiety of the synthesized dihydrazones.