Chiral binaphthylamine based emitters with donor-acceptor structures: Facile synthesis and circularly polarized luminescence

Abstract

Materials capable of circularly polarized luminescence (CPL) have generated intensive interest for their potential applications. However, constructing chiral molecules with tunable CPL signals remains a challenge. In this paper, two pairs of binaphthylamine based chiral donors R/S-2 and R/S-3 were synthesized by Pd-catalyzed C–N coupling and intramolecular oxidative coupling with good yields. Then three pairs of chiral D-A type molecules R/S-4∼6 can be synthesized by introducing two kinds of achiral acceptors. The extention of the chiral binaphthy skeleton endows these chiral compounds with CPL signals ranged from 417 nm to 544 nm in solutions and film states. The glum can be up to −2.9 × 10−3 for R-2 in solution. The introduction of terephthalonitrile as acceptor endow R/S-4 thermally activated delayed fluorescence (TADF). Furthermore, when benzophenone is chosen as achiral acceptor, the obtained chiral D-A molecules R/S-5 and R/S-6 can exhibit reversed CPL signals compared with their corresponding chiral donors. This work demonstrates the introduction of chiral D-A structure not only alters the wavelength of the CPL signals but also can reverse the CPL sign.