title: Organometallic complexes for nonlinear optics. 43. Quadratic optical nonlinearities of dipolar alkynylruthenium complexes with phenyleneethynylene/phenylenevinylene bridges.
abstract: The syntheses of trans-[Ru(4,4'-C[triple bond]CC(6)H(4)C[triple bond]CC(6)H(4)NO(2))Cl(dppe)(2)] (19) and the systematically varied complexes trans-[Ru(4,4',4''-C[triple bond]CC(6)H(4)X(2)C(6)H(4)Y(2)C(6)H(4)NO(2))Cl(L(2))(2)] [L(2) = dppe, X(2) = C[triple bond]C, Y(2) = (E)-CH=CH (12), C[triple bond]C (18); L(2) = dppe, X(2) = (E)-CH=CH, Y(2) = C[triple bond]C (14), (E)-CH=CH (16); L(2) = dppm, X(2) = C[triple bond]C, Y(2) = (E)-CH=CH (13); L(2) = dppm, X(2) = (E)-CH=CH, Y(2) = C[triple bond]C (15), (E)-CH=CH (17)] are reported, the latter being donor-bridge-acceptor complexes varying in bridge composition by replacement of yne with E-ene linkages, together with their cyclic voltammetric data, linear optical, and quadratic nonlinear optical response data. Ru(II/III) oxidation potentials increase on replacing yne linkage by E-ene linkage at the phenylene adjacent to the metal center, and on replacing dppe by dppm co-ligands. The low-energy optical absorption maxima occur in the region 20,400-23,300 cm(-1) and are metal-to-ligand charge-transfer (MLCT) in origin; these bands undergo a blue-shift upon pi-bridge lengthening by addition of phenyleneethynylene units, and on replacing E-ene linkages by yne linkages. Time-dependent density functional theory calculations on model complexes have suggested assignments for the low-energy bands. The optical spectra of selected oxidized species contain low-energy ligand-to-metal charge transfer (LMCT) bands centered in the region 9760-11,800 cm(-1). Quadratic molecular nonlinearities from hyper-Rayleigh scattering (HRS) studies at 1064 nm reveal an increase in the two-level-corrected beta(0) value on pi-bridge lengthening, a trend that is not seen with beta values because of the blue-shift in lambda(max) for this structural modification. Replacing yne linkages by E-ene linkage at the phenylene adjacent to the metal center or dppm co-ligand by dppe results in an increase in beta and beta(0) values. In contrast, quadratic molecular nonlinearities by HRS at 1300 nm or electric field-induced second-harmonic generation (EFISH) studies at 1907 nm do not afford clear trends.
authors.affiliation: Department of Chemistry, Australian National University, Canberra, ACT 0200, Australia.
authors.forename: Luca
authors.initials: L
authors.lastname: Rigamonti
authors.forename: Bandar
authors.initials: B
authors.lastname: Babgi
authors.forename: Marie P
authors.initials: MP
authors.lastname: Cifuentes
authors.forename: Rachel L
authors.initials: RL
authors.lastname: Roberts
authors.forename: Simon
authors.initials: S
authors.lastname: Petrie
authors.forename: Robert
authors.initials: R
authors.lastname: Stranger
authors.forename: Stefania
authors.initials: S
authors.lastname: Righetto
authors.forename: Ayele
authors.initials: A
authors.lastname: Teshome
authors.forename: Inge
authors.initials: I
authors.lastname: Asselberghs
authors.forename: Koen
authors.initials: K
authors.lastname: Clays
authors.forename: Mark G
authors.initials: MG
authors.lastname: Humphrey
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D004987:Ethers / Q000737:chemistry*; D008956:Models, Chemical; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*; D014753:Vinyl Compounds / Q000737:chemistry*
chemical_list: D000480:Alkynes; D004987:Ethers; D009942:Organometallic Compounds; D014753:Vinyl Compounds; C436384:phenyleneethynylene; D012428:Ruthenium