Syntheses and Optical Properties of Azo-Functionalized Ruthenium Alkynyl Complexes

We thank the Australian Research Council (ARC), the National Natural Science Foundation of China (51432006), and the Chinese Government Ministry of Education and State Administration of Foreign Experts Affairs (111 Project: B13025) for financial support. M.P.C. thanks the ARC for an Australian Research Fellowship

Synthesis, Optical, Electrochemical, and Theoretical Studies of Dipolar Ruthenium Alkynyl Complexes with Oligo(phenylenevinylene) Bridges

We thank the Australian Research Council (ARC), the National Natural Science Foundation of China (51432006), the Chinese Government Ministry of Education, and the Chinese Government State Administration of Foreign Experts Affairs (111 Project: B13025). M.P.C. thanks the ARC for an Australian Research Fellowship and C.Q. thanks CONICYT (Chile) for a Chile PhD Scholarship Abroad

Organometallic complexes for nonlinear optics.66. Synthesis and quadratic nonlinear optical studies of trans-[Ru{C=C{2,5-C4H2S-( E )-CH=CH}n-2,5-C4H2S(NO2 )}Cl(dppe)2](n1/40-2)

Oligo(2,5-thienylenevinylene)s (OTVs) end-functionalized with a ligated ruthenium alkynyl unit as adonor and a nitro as acceptor, namelytrans-[Ru{C^C-2,5-C4H2S(NO2)}Cl(dppe)2](Ru1T),trans-[Ru{C^C-2,5-C4H2S-(E)-CH]CH-2,5-C4H2S(NO2)}Cl(dppe)2](Ru2T), andtrans-[Ru{C^C-2,5-C4H2S-(E)-CH]CH-2,5-C4H2S-(E)-CH]CH-2,5-C4H2S(NO2)}Cl(dppe)2](Ru3T), have been synthesized, their elec-trochemical properties have been assessed by cyclic voltammetry (CV), their linear optical and quadratic nonlinear optical (NLO) properties have been assayed by UVeviseNIR spectroscopy and hyper-Rayleighscattering studies at 1300 nm, respectively, and their linear optical properties in the formally RuIII state have been examined by UVeviseNIR spectroelectrochemistry. The data for Ru1T-Ru3Thave beencompared to those of the oligo(p-phenylenevinylene) (OPV) analoguestrans-[Ru(C^C-1,4-C6H4NO2)Cl(dppe)2](Ru1P),trans-[Ru{C^C-1,4-C6H4-(E)-CH]CH-1,4-C6H4NO2}Cl(dppe)2](Ru2P), andtrans-[Ru{C^C-1,4-C6H4-(E)-CH]CH-1,4-C6H4-(E)-CH]CH-1,4-C6H4NO2}Cl(dppe)2](Ru3P). The RuII/IIIoxidationpotentials decrease on proceeding fromRu1TtoRu3T, while the wavelength of the UVevislmaxbandincreases on proceeding fromRu1TtoRu2T, but thereafter decreases on further progression toRu3T, similar trends to those seen proceeding fromRu1PtoRu3P. The quadratic nonlinearityb1300 increases on OTV lengthening from Ru1TthroughRu2TtoRu3T; the data are significantly larger than those of the Ru1PeRu3Panalogues which peak atRu2P. The formally RuIIIcomplexes exhibit low-energy bands thatred-shift significantly on proceeding fromRu1TtoRu3T. Computational studies employing time-dependent density functional theory were undertaken on model complexes to rationalize the optical observations and explore the impact of further OTV bridge lengthening. Computational studies on modelcomplexesRu1T′-Ru6T′are consistent with decreasing contributions of the electron donor (ligated Ru) and acceptor (NO2) groups to the HOMO and LUMO, respectively, up n-bridge lengthening.btotvalues increase on progression fromRu1T′toRu3T′, but thereafter further bridge lengthening affords little further increase in b-tot, consistent with a saturation in quadratic NLO response.We thank the Australian Research Council (ARC: DP170100408),the National Natural Science Foundation of China (51432006), theChinese Government Ministry of Education, and the Chinese Gov-ernment State Administration of Foreign Experts Affairs (111 Proj-ect: B13025). J. D. thanks the China Scholarship Council and theAustralian National University for a CSC-ANU PhD Scholarship

Organometallic complexes for nonlinear optics. 66. Synthesis and quadratic nonlinear optical studies of trans -[Ru{C=C{2,5-C4H2S-(E)- CH=CH}(n)-2,5-C4H2S(NO2)}Cl(dppe)(2)] (n=0-2)

status: publishe

Quadratic and Cubic Optical Nonlinearities of Y-Shaped and Distorted-H-Shaped Arylalkynylruthenium Complexes

Straightforward syntheses of bis[bis{1,2-bis(diphenylphosphino)ethane}ruthenium]-functionalized 1,3,5-triethynylbenzene-cored complexes via a methodology employing "steric control" permit facile formation of Y-shaped Sonogashira coupling products and distorted-H-shaped homo-coupled quadrupolar products. Cyclic voltammetric data from these products reveal two reversible metal alkynyl-localized oxidation processes for all complexes. The wavelengths of the linear optical absorption maxima are dominated by the nature of the peripheral alkynyl ligand rather than the substituent at the unique arm of the "Y" or at the quadrupolar complex "core". The quadratic optical nonlinearities of the Y-shaped complexes were assessed by the hyper-Rayleigh scattering technique at 800 nm and employing 100 fs light pulses; introduction of donor NEt2 and/or acceptor NO2 to the wedge periphery resulted in non-zero nonlinearities, with the largest βHRS,800 values being observed for the complexes containing the 4-nitrophenylalkynyl ligands. Depolarization ratios are consistent with substantial off-diagonal first hyperpolarizability tensor components and 2D nonlinear character. Computational studies employing time-dependent density functional theory have been employed to assign the key low-energy transitions in the linear optical spectra and to compute the quadratic nonlinear optical tensorial components. Cubic optical nonlinearities of the quadrupolar complexes were assessed by the Z-scan technique over the range 500-1600 nm and employing 130 fs light pulses; two-photon absorption cross-sections for these distorted-H-shaped complexes are moderate to large in value (up to 5500 GM at 880 nm), while one example displays significant three-photon absorption (1300×10-80  cm6  s2 at 1200 nm).status: publishe

Linear Optical, Quadratic and Cubic Nonlinear Optical, Electrochemical, and Theoretical Studies of "Rigid-Rod" Bis-Alkynyl Ruthenium Complexes

The syntheses of oligo(p-phenylene ethynylene)s (OPEs) end-functionalized by a nitro acceptor group and with a ligated ruthenium unit at varying locations in the OPE chain, namely, trans-[Ru{(C≡C-1,4-C6 H4 )n NO2 }(C≡CR)(dppe)2 ] (dppe=1,2-bis(diphenylphosphino)ethane; n=1, R=1,4-C6 H4 C≡C-1,4-C6 H4 C≡CPh, 1,4-C6 H4 NEt2 ; n=2, R=Ph, 1,4-C6 H4 C≡CPh, 1,4-C6 H4 C≡C-1,4-C6 H4 C≡CPh, 1,4-C6 H4 NO2 , 1,4-C6 H4 NEt2 ; n=3, R=Ph, 1,4-C6 H4 C≡CPh), are reported. Their electrochemical properties were assessed by cyclic voltammetry, their linear optical properties and quadratic and cubic nonlinear optical properties were assayed by UV/Vis/NIR spectroscopy, hyper-Rayleigh scattering studies employing nanosecond pulses at 1064 nm, and broad spectral range Z-scan studies employing femtosecond pulses, respectively, and their linear optical properties and vibrational spectroscopic behavior in the formally RuIII state was examined by UV/Vis/NIR and IR spectroelectrochemistry, respectively. The potentials of the metal-localized oxidation processes are sensitive to alkynyl-ligand modification, but this effect is attenuated on π-bridge lengthening. Computational studies employing time-dependent density functional theory were undertaken on model complexes, with a 2D scan revealing a soft potential-energy surface for intra-alkynyl-ligand aryl-ring rotation; this is consistent with the experimentally observed blueshift in optical absorption maxima. Quadratic optical nonlinearities are significant and cubic NLO coefficients for these small complexes are small. The optimum length of the alkynyl ligands and the ideal metal location in the OPE to maximize the key coefficients have been defined.status: publishe