| Autor: |
Sejie FP; Department of Chemistry, University of Botswana, Gaborone Private Bag UB 00704, Botswana., Oyetunji OA; Department of Chemistry, University of Botswana, Gaborone Private Bag UB 00704, Botswana., Darkwa J; Botswana Institute for Technology Research and Innovation, Gaborone Private Bag 0082, Botswana.; Department of Chemical Sciences, University of Johannesburg, P.O. Box 524, Auckland Park 2006, South Africa., Beas IN; Botswana Institute for Technology Research and Innovation, Gaborone Private Bag 0082, Botswana., Makhubela BCE; Department of Chemical Sciences, University of Johannesburg, P.O. Box 524, Auckland Park 2006, South Africa., Dzade NY; Department of Energy and Mineral Engineering, Pennsylvania State University, University Park, PA 16802, USA.; School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK., de Leeuw NH; School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK.; School of Chemistry, University of Leeds, Leeds LS2 9JT, UK. |
| Abstrakt: |
The imino pyridine Schiff base cobalt(II) and nickel(II) complexes ( C1 and C2 ) and their functionalised γ-Fe 3 O 4 counterparts ( Fe 3 O 4 @C1 and Fe 3 O 4 @C2 ) were synthesised and characterised using IR, elemental analysis, and ESI-MS for C1 and C2 , and single crystal X-ray diffraction for C1 , while the functionalised materials Fe 3 O 4 @C1 and Fe 3 O 4 @C2 were characterized using IR, XRD, SEM, TEM, EDS, ICP-OES, XPS and TGA. Complexes C1 , C2 and the functionalised materials Fe 3 O 4 @C1 and Fe 3 O 4 @C2 were tested as catalysts for the selective transfer hydrogenation of cinnamaldehyde and all four pre-catalysts showed excellent catalytic activity. Complexes C1 and C2 acted as homogeneous catalysts with high selectivity towards the formation of hydrocinnamaldehyde (88.7% and 92.6%, respectively) while Fe 3 O 4 @C1 and Fe 3 O 4 @C2 acted as heterogeneous catalysts with high selectivity towards cinnamyl alcohol (89.7% and 87.7%, respectively). Through in silico studies of the adsorption energies, we were able to account for the different products formed using the homogeneous and the heterogeneous catalysts which we attribute to the preferred interaction of the C=C moiety in the substrate with the Ni centre in C2 (-0.79 eV) rather than the C=O (-0.58 eV). |
