Heptametallic, Octupolar Nonlinear Optical Chromophores with Six Ferrocenyl Substituents

New complexes with six ferrocenyl (Fc) groups connected to ZnII or Cd^(II) tris(2,2′-bipyridyl) cores are described. A thorough characterisation of their BPh_(4)− salts includes two single-crystal X-ray structures, highly unusual for such species with multiple, extended substituents. Intense, visible d(Fe^(II))→π* metal-to-ligand charge-transfer (MLCT) bands accompany the π→π* intraligand charge-transfer absorptions in the near UV region. Each complex shows a single, fully reversible Fe^(III/II) wave when probed electrochemically. Molecular quadratic nonlinear optical (NLO) responses are determined by using hyper-Rayleigh scattering and Stark spectroscopy. The latter gives static first hyperpolarisabilities β_0 reaching as high as approximately 10^(−27) esu and generally increasing with π-conjugation extension. Z-scan cubic NLO measurements reveal high two-photon absorption cross-sections σ2 of up to 5400 GM in one case. DFT calculations reproduce the π-conjugation dependence of β_0, and TD-DFT predicts three transitions close in energy contributing to the MLCT bands. The lowest energy transition has octupolar character, whereas the other two are degenerate and dipolar in nature

Nonlinear Optical Chromophores with Two Ferrocenyl, Octamethylferrocenyl, or 4‑(Diphenylamino)phenyl Groups Attached to Rhenium(I) or Zinc(II) Centers

The compounds 4,4′-bis[(E)-2-R-vinyl]-2,2′-bipyridyl {R = ferrocenyl [(Fcv)_2bpy], octamethylferrocenyl [(Me_8Fcv)_2bpy] or 4-(diphenylamino)phenyl [(Dapv)_2bpy]} are used to prepare eight new complexes with Zn^(II)Cl_2, Zn^(II)(OAc)_2, or fac-Re^ICl(CO)_3 centers. The recently reported complex fac-Re^ICl(CO)_3[(Dapv)_2bpy] (Horvath, R. et al. Inorg. Chem. 2013, 52, 1304) is also studied. Electronic absorption spectra show intense d → π^* metal-to-ligand charge-transfer (MLCT) and π → π^* intraligand charge-transfer (ILCT) absorption bands, the relative energies of which correlate logically with the molecular structure. Cyclic voltammetry reveals a reversible oxidation wave for the Fc/Me_8Fc complexes, accompanied by quasireversible or irreversible ligand-based reductions. The Re complexes also show irreversible Re^(II/I) waves. Single-crystal X-ray structures are reported for (Me_8Fcv)_2bpy, Zn^(II)Cl_2[(Me_8Fcv)_2bpy], Zn^(II)(OAc)_2[(Fcv)_2bpy]·CHCl_3, and fac-Re^ICl(CO)_3[(Me_8Fcv)_2bpy]·0.5CHCl_3. Molecular first hyperpolarizabilities β are measured in DCM solutions via the hyper-Rayleigh scattering (HRS) technique at 1300 nm. Stark (electroabsorption) spectroscopic studies on only the MLCT bands in frozen butyronitrile allow the indirect estimation of lower limits for the overall static first hyperpolarizabilities β_0. Time-dependent density functional theory (TD-DFT) calculations on selected complexes confirm the expected assignments of their low energy absorption bands, with the best results obtained by using the M06 functional and Def2-TZVP/SVP/TZVPP mixed basis set. DFT predicts that the total static first hyperpolarizability β_(tot) increases in the Zn^(II)Cl_2 series in the order R = Fc < Me_8Fc < Dap, consistent with the HRS and Stark data. The computed β values increase substantially on moving from the gas phase to a DCM or MeCN solvent medium, and the essentially 2D nature of the chromophores leads to dominant β_(xxy) tensor components

Synthesis, Structures, and Optical Properties of Ruthenium(II) Complexes of the Tris(1-pyrazolyl)methane Ligand

Four new complex salts [Ru^(II)Cl(Tpm)(L^A)_2][PF_6]_n [Tpm = tris(1-pyrazolyl)methane; n = 1, L^A = pyridine (py) 1 or ethyl isonicotinate (EIN) 2; n = 3, L^A = N-methyl-4,4′-bipyridinium (MeQ^+) 3 or N-phenyl-4,4′-bipyridinium (PhQ^+) 4] have been prepared and characterized. Electronic absorption spectra show intense d → π^* metal-to-ligand charge-transfer (MLCT) absorption bands, while cyclic voltammetry reveals a reversible Ru^(III/II) wave, accompanied by quasireversible or irreversible L^A-based reductions for all except 1. Single crystal X-ray structures have been obtained for 1•Me_2CO, 2, and 3•Me_2CO. For 2–4, molecular first hyperpolarizabilities β have been measured in acetonitrile solutions via the hyper-Rayleigh scattering (HRS) technique at 800 nm. Stark (electroabsorption) spectroscopic studies on the MLCT bands in frozen butyronitrile allow the indirect estimation of static first hyperpolarizabilities β_0. The various physical data obtained for 3 and 4 are compared with those reported previously for related cis-{Ru^(II)(NH_3)_4}^(2+) species [Coe, B. J. et al. J. Am. Chem. Soc. 2005, 127, 4845]. TD-DFT calculations on the complexes in 1–4 confirm that their lowest energy absorption bands are primarily Ru^(II) → L^A MLCT in character, while Ru^(II) → Tpm MLCT transitions are predicted at higher energies. DFT agrees with the Stark, but not the HRS measurements, in showing that β_0 increases with the electron-accepting strength of L^A. The 2D nature of the chromophores is evidenced by dominant β_(xxy) tensor components

Experimental and simulation study of the Schottky barrier lowering by substrate doping variation for PtSi Source/Drain SBFETs

peer reviewedIn this paper, the authors study experimentally and numerically the Schottky barrier height (SBH) lowering of Pt silicide/n-Si diodes and its implications to Schottky-barrier (SB) source/drain p-FETs. The authors demonstrate that hole SBH can be lowered through an image-force mechanism by increasing the n-Si substrate doping, which leads to a substantial gain of the drive current in the long-channel bulk p-SBFETs. Numerical simulations show that the channel doping concentration is also critical for short-channel n- & p-SOI SBFETs performanc

The Genome of the Fungal Pathogen Verticillium dahliae Reveals Extensive Bacterial to Fungal Gene Transfer

Horizontal gene transfer (HGT) involves the transmission of genetic material between distinct evolutionary lineages and can be an important source of biological innovation. Reports of interkingdom HGT to eukaryotic microbial pathogens have accumulated over recent years. Verticillium dahliae is a notorious plant pathogen that causes vascular wilt disease on hundreds of plant species, resulting in high economic losses every year. Previously, the effector gene Ave1 and a glucosyltransferase-encoding gene were identified as virulence factor-encoding genes that were proposed to be horizontally acquired from a plant and a bacterial donor, respectively. However, to what extent HGT contributed to the overall genome composition of V. dahliae remained elusive. Here, we systematically searched for evidence of interkingdom HGT events in the genome of V. dahliae and provide evidence for extensive horizontal gene acquisition from bacterial origin

Nonlinear Optical Chromophores with Two Ferrocenyl, Octamethylferrocenyl, or 4-(Diphenylamino)phenyl Groups Attached to Rhenium(I) or Zinc(II) Centers

© 2015 American Chemical Society. The compounds 4,4′-bis[(E)-2-R-vinyl]-2,2′-bipyridyl {R = ferrocenyl [(Fcv)2bpy], octamethylferrocenyl [(Me8Fcv)2bpy] or 4-(diphenylamino)phenyl [(Dapv)2bpy]} are used to prepare eight new complexes with ZnIICl2, ZnII(OAc)2, or fac-ReICl(CO)3 centers. The recently reported complex fac-ReICl(CO)3[(Dapv)2bpy] (Horvath, R. et al. Inorg. Chem. 2013, 52, 1304) is also studied. Electronic absorption spectra show intense d → π∗ metal-to-ligand charge-transfer (MLCT) and π → π∗ intraligand charge-transfer (ILCT) absorption bands, the relative energies of which correlate logically with the molecular structure. Cyclic voltammetry reveals a reversible oxidation wave for the Fc/Me8Fc complexes, accompanied by quasireversible or irreversible ligand-based reductions. The Re complexes also show irreversible ReII/I waves. Single-crystal X-ray structures are reported for (Me8Fcv)2bpy, ZnIICl2[(Me8Fcv)2bpy], ZnII(OAc)2[(Fcv)2bpy]·CHCl3, and fac-ReICl(CO)3[(Me8Fcv)2bpy]·0.5CHCl3. Molecular first hyperpolarizabilities β are measured in DCM solutions via the hyper-Rayleigh scattering (HRS) technique at 1300 nm. Stark (electroabsorption) spectroscopic studies on only the MLCT bands in frozen butyronitrile allow the indirect estimation of lower limits for the overall static first hyperpolarizabilities β0. Time-dependent density functional theory (TD-DFT) calculations on selected complexes confirm the expected assignments of their low energy absorption bands, with the best results obtained by using the M06 functional and Def2-TZVP/SVP/TZVPP mixed basis set. DFT predicts that the total static first hyperpolarizability βtot increases in the ZnIICl2 series in the order R = Fc 8Fc xxy tensor components.status: publishe

The genome of the fungal pathogen Verticillium dahliae reveals extensive bacterial to fungal gene transfer

Horizontal gene transfer (HGT) involves the transmission of genetic material between distinct evolutionary lineages and can be an important source of biological innovation. Reports of inter-kingdom HGT to eukaryotic microbial pathogens have accumulated over recent years. Verticillium dahliae is a notorious plant pathogen that causes vascular wilt disease on hundreds of plant species, resulting in high economic losses every year. Previously, the effector gene Ave1 and a glucosyltransferase-encoding gene were identified as virulence factor-encoding genes that were proposed to be horizontally acquired from a plant and a bacterial donor, respectively. However, to what extent HGT contributed to the overall genome composition of V. dahliae remained elusive. Here, we systematically searched for evidence of inter-kingdom HGT events in the genome of V. dahliae and provide evidence for extensive horizontal gene acquisition from bacterial origin