Anionic Iron(III) Porphyrin Immobilized on/into Exfoliated Macroporous Layered Double Hydroxides as Catalyst for Oxidation Reactions

Shirley Nakagaki,Claude Forano,Matilte Halma,Fernando Wypych,Vanessa Prévot,Geani M Ucoski,Kelly A D F Castro

doi:10.5935/0103-5053.20140241

Abstract

The oxidation of organic substrates via catalytic routes is an important class of reactions to produce industrial input materials such as epoxides, alcohols, and ketones. Metalloporphyrins display recognized catalytic activity that mimics oxidation processes in living organisms. Their immobilization in different inert supports allows their recovery and reuse in heterogeneous catalytic processes. Layered double hydroxides (LDHs) are inorganic materials consisting of di- and trivalent metal hydroxides that afford bidimensional positively charged layers. This work reports on the preparation of the solid based on macroporous LDHs (LDHMs) by the co-precipitation method, which involved the use of polystyrene as template, oxides reconstruction, and exfoliation, to furnish LDHME. We also describe the immobilization of an iron(III) porphyrin (FeP) in LDHME and in LDH intercalated with nitrate anions, obtained by the co-precipitation method. Application of the immobilized catalysts in (Z)-cyclooctene and cyclohexane oxidation will help to assess their catalytic activity.

Highlights

The family of enzymes collectively known as cytochrome P450 monooxygenases bear a heme prosthetic group and participate in different catalytic processes, mainly oxidative metabolism of endogenous/exogenous products in mammals.[1,2,3,4,5]Over the last years, researchers have made great efforts to develop routes that can generate robust synthetic metalloporphyrins (MPs),[6,7,8,9,10] aiming to mimic biological enzymes such as cytochrome P450
In the presence of dodecyl sulfate (DDS) solution, the lamellar structure of Layered double hydroxides (LDHs)-NO3 re-emerged, whilst DDS intercalated within the macropores
This work described the preparation of two solid catalysts via immobilization of the anionic [Fe(TDCSPP)] in LDH supports, with the aim to compare the influence of supports with the same composition but different structures in the catalytic activity of the iron complex during the oxidation of two model substrates

Summary

Introduction

The family of enzymes collectively known as cytochrome P450 monooxygenases bear a heme prosthetic group and participate in different catalytic processes, mainly oxidative metabolism of endogenous/exogenous products in mammals.[1,2,3,4,5]Over the last years, researchers have made great efforts to develop routes that can generate robust synthetic metalloporphyrins (MPs),[6,7,8,9,10] aiming to mimic biological enzymes such as cytochrome P450 (biomimetic approach). We have prepared two solids by immobilizing the [Fe(TDCSPP)Cl] (Figure 1) - FeP - in different LDH supports, namely LDH containing intercalated nitrate anions (LDH-NO3) and exfoliated macroporous LDH (LDHME) (the iron porphyrin [Fe(TDCSPP)Cl] will be abbreviated as FeP by simplification; in this representation charges and counter ion Cl1− are omitted).

Results

Conclusion