Journal of the chemical society-dalton transactions issue:1 pages:29-36
The novel series of monometallic monocations Fc-[n]-Az(+) and Fc-[n]-Guaz(+) (where Az(+) and Guaz(+) denote azulenylium and guaiazulenylium cations respectively and n=0-3), and a bimetallic dicationic complex Fc--Guaz(RuCp)(2+) have been prepared. Single crystal structures of Fc--Guaz(+) and Fc--Guaz(RuCp)(2+) have been determined. Analysis of the bond lengths and angles coupled with the electrochemistry data provides evidence for strong ground state charge transfer in the series which diminishes upon pi -bridge extension. The electronic absorption spectra reveal that alkylation of the cationic terminus (1) diminishes the electron-accepting ability, (2) results in a larger dipole moment change upon excitation and (3) causes a smaller sequential lowering of the CT transitions with pi -bridge extension. The NLO properties which were characterised by hyper-Rayleigh scattering techniques indicate the potential of the azulenylium based donor-acceptor chromophores, but also that the extended complexes exhibit two-photon absorption fluorescence.