Rigid rod-like molecular wires of nanometric dimension. Electronic energy transfer from a naphthyl to an anthracenyl unit connected by a 1,4-pentaphenylene spacer

We have synthesized the multicomponent species N-(ph)(5)-A, where a l-napht hyl (N-) and a 9-anthryl (-A) units are connected by a 1,4-pentaphenylene r od-like spacer (-(ph)(5)-). The overall length of the compound is 3.1 nm an d the center-to-center distance between the naphthyl and anthryl units is 2 .6 nm. The absorption and emission spectra of N-(ph),-A have been investiga ted in cyclohexane solution at 293 K and compared with those of model compo unds of the component units. Emission spectra, fluorescence quantum yields and excited state Lifetimes show that in N-(ph)(5)-A the fluorescence of th e naphtyl and oligophenyl units is completely quenched by energy transfer t o the fluorescent excited state of the anthryl unit. The mechanism of the e nergy transfer process is discussed. (C) 2000 Elsevier Science S.A. All rig hts reserved.