Luminescence-kinetic spectroscopy of compound complexes of polyphenylquinolines

Polyphenylquinolines (PPQs), which are compound donor–acceptor complexes, are studied by luminescence-kinetic spectroscopy. It is shown that, as the $\pi$ system becomes stronger on passing from (O, C) to (O, IC) and (PhA, C), an increase in the lifetime $T$ of the excited state is first observed, and for the strongest charge-transfer complex PPQ (PhA, IC), whose luminescence kinetics is described by two exponentials, the lifetime decreases to a value equal to $T$ of PPQ (O, C). This indicates that this complex has two emitting centers localized in the arylene moiety and in the phenylquinoline ring and thereby confirms a previously made conclusion that compound donor–acceptor complexes are formed in polyphenylquinolines with a branched $\pi$ system of compound D–A complexes.