Porphyrin–Nanodiamond Hybrid Materials—Active, Stable and Reusable Cyclohexene Oxidation Catalysts
Lucas D. Dias (Universidade de Coimbra, Universidade de São Paulo)
Fábio M.S. Rodrigues (Universidade de Coimbra)
Mário J.F. Calvete (Universidade de Coimbra)
Sónia A.C. Carabineiro (Universidade Nova de Lisboa, Universidade do Porto)
Marisa D. Scherer (University of Caxias do Sul)
Anderson R.L. Caires (University of Essex, University of Caxias do Sul)
J.G. Buijnsters (TU Delft - Mechanical Engineering)
José L. Figueiredo (Universidade do Porto)
Vanderlei S. Bagnato (Texas A&M University, Universidade de São Paulo)
Mariette M. Pereira (Universidade de Coimbra)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
The quest for active, yet “green” non-toxic catalysts is a continuous challenge. In this work, covalently linked hybrid porphyrin–nanodiamonds were prepared via ipso nitro substitution reaction and characterized by X-ray photoelectron spectroscopy (XPS), fluorescence spectroscopy, infrared spectroscopy (IR) and thermogravimetry-differential scanning calorimetry (TG-DSC). The amine-functionalized nanodiamonds (ND@NH2) and 2-nitro-5,10,15,20-tetra(4-trifluoromethylphenyl)porphyrin covalently linked to nanodiamonds (ND@βNH-TPPpCF3) were tested using Allium cepa as a plant model, and showed neither phytotoxicity nor cytotoxicity. The hybrid nanodiamond–copper(II)–porphyrin material ND@βNH-TPPpCF3-Cu(II) was also evaluated as a reusable catalyst in cyclohexene allylic oxidation, and displayed a remarkable turnover number (TON) value of ≈265,000, using O2 as green oxidant, in the total absence of sacrificial additives, which is the highest activity ever reported for said allylic oxidation. Additionally, ND@βNH-TPPpCF3-Cu(II) could be easily separated from the reaction mixture by centrifugation, and reused in three consecutive catalytic cycles without major loss of activity.
help_outline