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Browsing by Author "Piedade, M. F. M."

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  • pH-switchability and second-order nonlinear optical properties of monocyclopentadienylruthenium(II)/iron(II) tetrazoles/tetrazolates: synthesis, characterization, and time-dependent density functional theory calculations
    Publication . Florindo, Pedro R.; Costa, Paulo J.; Piedade, M. F. M.; Robalo, Maria Paula
    Tetrazole/tetrazolate monocydopentadienyliron(II) and ruthenium(II) compounds of general formulas [(eta(5)-C5H5)M(dppe)(N-4(H)CC6H4NO2)][PF6]/[(eta(5)-C5H5)M(dppe)(N4CC6H4NO2] were investigated for their pH-switching second-order nonlinear optical (SONLO) properties. Compounds [(eta(5)-C5H5)M(dppe)(N4CC6H4NO2) (M = Fe, Ru) and compound [(eta(5)-C5H5)Ru(dppe)(N-4(H)CC6H4NO2)][PF6] were fully characterized by (H-1-, C-13-, P-31-) NMR, cyclic voltammetty, and elemental analysis, and compounds [(eta(5)-C5H5)Fe(dppe)(N4CC6H4NO2)] and [(eta(5)-C5H5)Ru(dppe)(N-4(H)CC6H4NO2)][PF6] were further characterized by single-crystal X-ray diffraction; the synthesis of [(eta(5)-C5H5)Fe(dppe)(N-4(H)CC6H4NO2)][PF6] was unsuccessful. Time-dependent density functional theory calculations were performed using PBE0 and CAM-B3LYP functionals to evaluate the first hyperpolarizability (beta(tot)) of the tetrazole/tetrazolate complexes and for a detailed analysis of the experimental data. Both functionals piedict (i) high first hyperpolarizabilities for the tetrazolate complexes [(eta(5)-C5H5)M(dppe)(N4CC6H4NO2)], with beta(tot)[Ru] approximate to 1.2 beta(tot)[Fe], and (ii) a 3-fold reduction in beta(tot)[Ru] protonation, in complex [(eta(5)-C5H5)Ru(dppe)(N-4(H)CC6H4NO2)](+), forecasting [(eta(5)-C5H5)Ru(dppe)(N4CC6H4NO2)]/[(eta(5)-C5H5)Ru(dppe)(N-4(H)CC6H4NO2)](+) complexes as on/off, pH-switchable SONLO forms.
    2017-06-19Journal article Restricted access Show more
  • Synthesis and structural characterization of new Piano-stool Ruthenium(II) complexes bearing 1-Butylimidazole heteroaromatic ligand
    Publication . Morais, Tânia S.; Garcia, M. Helena; Robalo, Maria Paula; Piedade, M. F. M.; Duarte, M. Teresa; Brito, M. José Villa de; Madeira, Paulo J. Amorim
    New cationic ruthenium(II) complexes with the formula [Ru(eta(5)-C5H5)(LL)(1-BuIm)] [Z], with (LL) = 2PPh(3) or DPPE, and Z = CF3SO3-, PF6-, BPh4-, have been synthesized and fully characterized. Spectroscopic and electrochemical studies revealed that the electronic properties of the coordinated 1-butylimidazole were clearly influenced by the nature of the phosphane coligands (LL) and also by the different counter ions. The solid state structures of the six complexes determined by X-ray crystallographic studies, confirmed the expected distorted three-legged piano stool structure. However the geometry of the 1-butylimidazole ligand was found considerably different in all six compounds, being governed by the stereochemistry of the mono and bidentate coligands (PPh3 or DPPE).
    2012-08-15Journal article Restricted access Show more