title: Highly unusual effects of pi-conjugation extension on the molecular linear and quadratic nonlinear optical properties of ruthenium(II) ammine complexes.
abstract: We have used several techniques, including hyper-Rayleigh scattering and Stark spectroscopy, to investigate the effects of polyene chain length on the optical properties of complexes containing ruthenium(II) electron donor groups and pyridinium electron acceptors. In marked contrast with all other known donor-acceptor polyenes, conjugation extension beyond a single double bond in the dipolar complexes studied leads to blue-shifting of the intramolecular charge-transfer absorptions. Furthermore, the static first hyperpolarizabilities beta0 become maximized with trans-1,3-butadienyl linkages and then decrease in complexes with three CH=CH bonds. Our results clearly demonstrate that the molecular engineering criteria for metal-containing nonlinear optical chromophores can differ dramatically from those for purely organic compounds.
authors.affiliation: Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, U.K. b.coe@man.ac.uk
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Coe
authors.forename: Lathe A
authors.initials: LA
authors.lastname: Jones
authors.forename: James A
authors.initials: JA
authors.lastname: Harris
authors.forename: Bruce S
authors.initials: BS
authors.lastname: Brunschwig
authors.forename: Inge
authors.initials: I
authors.lastname: Asselberghs
authors.forename: Koen
authors.initials: K
authors.lastname: Clays
authors.forename: André
authors.initials: A
authors.lastname: Persoons