Yan Zhu, A. Kulkarni, Pei-Tzu Wu
Jun 4, 2008
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Journal
Chemistry of Materials
Abstract
We report the synthesis and structural, photophysical, and electrochemical properties of a series of eight new phenoxazine-based donor−acceptor molecules utilizing phenoxazine as a common donor and quinoline, quinoxaline, benzoylquinoxaline, and benzoquinoxaline as various electron acceptor moieties. The phenoxazine−phenylquinoline molecules crystallized in the monoclinic system with the space groups C2/c and P21/c, respectively, revealing a 169° dihedral angle in the phenoxazine unit. The new materials had high glass transition temperatures (128−193 °C) and ambipolar redox properties with reversible electrochemical oxidation and reduction. Their HOMO levels were at 5.1−5.2 eV, whereas their LUMO levels (2.3−3.0 eV) increased with the electron acceptor strength. The materials showed intramolecular charge transfer fluorescence in dilute solutions with emission colors varying from blue to red and a quantum yield ranging from 86% in the phenoxazine−biphenyl molecule to as low as 16% in the benzoquinoxaline-c...