Synthesis, Structure, and Electroluminescence of BR₂q (R = Et, Ph, 2-Naphthyl and q = 8-Hydroxyquinolato)

Abstract

Three 8-hydroxyquinolato (q) boron compounds B(C 2 H 5 ) 2 q ( 1 ), BPh 2 q ( 2 ), and B(2-naph) 2 q ( 3 ) have been synthesized by the reaction of 8-hydroxyquinoline with an appropriate BR 3 compound. Compounds 1 − 3 have a tetrahedral geometry as demonstrated by the structure of 1 determined by a single-crystal X-ray diffraction analysis. Compounds 1 − 3 emit a green-blue color at λ max = 495−500 nm when irradiated by UV light. The electroluminescent (EL) properties of 2 and 3 were examined by fabricating EL devices using 2 and 3 as the light-emitting layer, respectively. The devices of 2 produce a yellow-green light with broad emission spectra, attributed to the formation of an exciplex of 2 with the N, N ‘ -di-1-naphthyl- N, N ‘ -diphenylbenzidine (NPB) in the hole transport layer while the intrinsic EL emission of compound 3 was observed. Both 2 and 3 were found to be good electron transport materials in EL devices.