Room Temperature Phosphorescent (RTP) N‐Acetylphenothiazines

Abstract

AbstractHerein we disclose a series of purely organic molecules (1–4) with a donor‐acceptor architecture (phenothiazine donor (D) and the acyl acceptor (A)) exhibiting room temperature dual phosphorescence (RTDP) characteristics. Detailed computational and photophysical studies revealed that the dual RTP bands with different wavelengths and lifetimes in these compounds originate from excited triplet states of different energies. In particular, the electronic nature of the substituent on the acceptor acyl unit has a significant effect on the energy of the ICT state, hybridization of excited states, as well as the rate of intersystem crossing. Compound 1 with an electron‐deficient CF3−CO acceptor moiety exhibit RTDP in the longer wavelength region. In contrast, compounds 2, 3 and 4 with weaker acceptors (2; CH3−CO, 3; CH3−CH2−CO and 4; (CH3)2−CH−CO) exhibit RTDP in a shorter wavelength region.