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Browsing by Author "Soliman, Mohamed M. A."

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  • Benzimidazole Schiff base copper(II) complexes as catalysts for environmental and energy applications: VOC oxidation, oxygen reduction and water splitting reactions
    Publication . Paul, Anup; Silva, Tiago A. R.; Soliman, Mohamed M. A.; Karacic, Jozo; Sljukic, Biljana; Alegria, Elisabete; Khan, Rais Ahmad; Guedes Da Silva, M. Fátima C.; Pombeiro, Armando
    The new copper(II) complexes [Cu(mu-1 kappa O:2 kappa ONN'-HL1)(mu-1 kappa O:2 kappa O'-NO3)](2)center dot[Cu(mu-1 kappa O:2 kappa ONN'-HL1)(CH3OH)](2)(NO3)(2) (1) and [Cu(kappa ONN'-HL2)(mu-1 kappa OO':2 kappa O'-NO3)](n) (2), derived from the new pro-ligands H(2)L1 = 2-(5,6-dihydroindolo[1,2-c]quinazolin-6-yl)-5-methylphenol and H(2)L2 = 2-(5,6-dihydroindolo[1,2-c]quinazolin-6-yl)-4-nitrophenol, were synthesized and characterized by elemental analysis, FT-IR, ESI-MS, and their structural features were unveiled by single-crystal X-ray diffraction analysis. This discloses a dimeric structure for 1 and a polymeric infinite 1D metal-organic chain for 2. The complexes were evaluated as catalysts for the oxidation of toluene, a volatile organic compound (VOC), and for oxygen reduction and water splitting reactions. 1 exhibits a higher activity for the peroxidative conversion of toluene to oxygenated products (total yields up to 38%), whereas 2 demonstrates a superior performance for electrochemical energy conversion applications, i.e., for oxygen reduction (ORR), oxygen evolution (OER) and hydrogen evolution (HER) reactions in an alkaline medium in terms of higher ORR current densities, lower Tafel slope (73 mV dec(-1)) and higher number of electrons exchanged (3.9), comparable to that of commercial Pt/C. Complex 2 also shows a better performance with lower onset potential and higher current densities for both OER and HER when studied as electrocatalyst for water splitting.
    2022-06-30Journal article Restricted access Show more
  • Mechanochemical preparation of Pd and Pt composites for Suzuki-Miyaura reactions
    Publication . Soliman, Mohamed M. A.; Da Costa Ribeiro, Ana Paula; Saraiva, Marta S.; Alegria, Elisabete; Pombeiro, Armando
    The application of green, simple, time- and energy-saving mechanochemical ball-milling procedures for the dispersion of palladium and platinum salts or oxides over MWCNTs (multi-walled carbon nanotubes) and activated carbon is reported. Carbon nanotubes have exceptional properties (e.g. high mechanical strength and surface areas) which make them promising materials for various applications. In this respect, we apply dispersed palladium and platinum composites [1-2] as catalysts in the Suzuki-Miyaura reactions. Both the preparation of the dispersed materials and the catalytic Suzuki-Miyaura reactions were performed by ball-milling and the results are discussed.
    2017-06Conference object Restricted access Show more
  • Vanadium(V) complexes supported on porous MIL-100(Fe) as catalysts for the selective oxidation of toluene
    Publication . Sutradhar, Manas; Marques, Guilherme; Soliman, Mohamed M. A.; Guedes Da Silva, M. Fátima C.; Flores, Daniela S. S.; Granadeiro, Carlos; Balula, Salete; Pombeiro, Armando; Alegria, Elisabete
    The vanadium(V) complexes bearing the aroylhydrazone Schiff base 2-hydroxy-N'-((2-hydroxynaphthalen-1-yl) methylene)benzohydrazide ligand [VO(OMe)L] (1) and [Et3NH][VO2L] (2) were synthesized, characterized and supported on porous MIL-100(Fe) forming the 1@MIL-100(Fe) and 2@MIL-100(Fe) composites. The outcome of such immobilizations was assessed by several characterization techniques, namely powder X-ray diffraction, UV/ Vis, FTIR, SEM-EDS, ICP and BET surface area analysis, confirming the successful heterogenization of both va-nadium complexes. They were screened as catalysts towards the oxidation of toluene, under homogenous (1 and 2) and heterogeneous (1@MIL-100 and 2@MIL-100) conditions. The influence of several parameters, namely the type and amount of catalyst or oxidant, reaction time, temperature, and radical trapping, was studied. The main products obtained were benzaldehyde, benzyl alcohol and benzoic acid. Under the optimized conditions, using 1 and 2 as homogeneous catalysts, total yields of 19 and 23%, respectively, were achieved at 80 degrees C after 6 h. Using 1@MIL100(Fe) and 2@MIL100(Fe) composites under heterogeneous conditions, total yields up to 11% after 24 h, were achieved.
    2022-08Journal article Restricted access Show more