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Browsing by Author "Mendes, Paulo J."

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  • Benzo[c]thiophene chromophores linked to cationic Fe and Ru derivatives for NLO materials: synthesis characterization and quadratic hyperpolarizabilities
    Publication . Silva, Tiago J. L.; Mendes, Paulo J.; Garcia, M. Helena; Robalo, Maria Paula; Ramalho, J. P. Prates; Carvalho, A. J. Palace; Buechert, Marina; Wittenburg, Christian; Heck, Juergen
    5-Monocyclopentadienyliron(II)/ruthenium(II) complexes of the general formula [M(5-C5H5)(PP)(L1)][PF6] {M = Fe, PP = dppe; M = Ru, PP = dppe or 2PPh3; L1 = 5-[3-(thiophen-2-yl)benzo[c]thiophenyl]thiophene-2-carbonitrile} have been synthesized and studied to evaluate their molecular quadratic hyperpolarizabilities. The compounds were fully characterized by NMR, FTIR and UV/Vis spectroscopy and their electrochemical behaviour studied by cyclic voltammetry. Quadratic hyperpolarizabilities () were determined by hyper-Rayleigh scattering measurements at a fundamental wavelength of 1500 nm. Density functional theory calculations were employed to rationalize the second-order non-linear optical properties of these complexes.
    2013-07Journal article Restricted access Show more
  • Mono(Eta(5)-cyclopentadienyl)metal(II) complexes with thienyl acetylide chromophores: synthesis, electrochemical studies, and first hyperpolarizabilities
    Publication . Silva, Tiago J. L.; Mendes, Paulo J.; Santos, Ana Margarida; Garcia, M. Helena; Robalo, Maria Paula; Ramalho, J. P. Prates; Carvalho, A. J. Palace; Buechert, Marina; Wittenburg, Christian; Heck, Juergen
    A series of mono(eta(5)-cyclopentadienyl)metal-(II) complexes with nitro-substituted thienyl acetylide ligands of general formula [M(eta(5)-C5H5)(L)(C C{C4H2S}(n)NO2)] (M = Fe, L = kappa(2)-DPPE, n = 1,2; M = Ru, L = kappa(2)-DPPE, 2 PPh3, n = 1, 2; M = Ni, L = PPh3, n = 1, 2) has been synthesized and fully characterized by NMR, FT-IR, and UV-Vis spectroscopy. The electrochemical behavior of the complexes was explored by cyclic voltammetry. Quadratic hyperpolarizabilities (beta) of the complexes have been determined by hyper-Rayleigh scattering (HRS) measurements at 1500 nm. The effect of donor abilities of different organometallic fragments on the quadratic hyperpolarizabilities was studied and correlated with spectroscopic and electrochemical data. Density functional theory (DFT) and time-dependent DFT (TDDFT) calculations were employed to get a better understanding of the second-order nonlinear optical properties in these complexes. In this series, the complexity of the push pull systems is revealed; even so, several trends in the second-order hyperpolarizability can still be recognized. In particular, the overall data seem to indicate that the existence of other electronic transitions in addition to the main MLCT clearly controls the effectiveness of the organometallic donor ability on the second-order NLO properties of these push pull systems.
    2014-09Journal article Restricted access Show more