Applied Catalysis A: General 413–414 (2012) 94–102 Contents lists available at SciVerse ScienceDirect Applied Catalysis A: General jo u r n al hom epage: www.elsevier.com/locate/apcata Anionic iron(III) porphyrins immobilized on zinc hydroxide chloride as catalysts for heterogeneous oxidation reactions Guilherme Sippel Machado a,b , Fernando Wypych b , Shirley Nakagaki a,∗ a Universidade Federal do Paraná, Departamento de Química – Laboratório de Bioinorgânica e Catálise – CP 19081, CEP 81531-980, Curitiba, Paraná, Brazil b Universidade Federal do Paraná, Departamento de Química – Centro de Pesquisa em Química Aplicada (CEPESQ) – CP 19081, CEP 81531-980, Curitiba, Paraná, Brazil a r t i c l e i n f o Article history: Received 4 July 2011 Received in revised form 17 October 2011 Accepted 28 October 2011 Available online 4 November 2011 Keywords: Porphyrin Zinc hydroxide chloride Heterogeneous catalyst Oxidation a b s t r a c t This work describes the immobilization of an anionic iron(III) porphyrin (FePor) family on zinc hydroxide chloride (ZHC), a layered hydroxide salt prepared by reacting an aqueous zinc chloride solution with an ammonium hydroxide solution. The FePor immobilization was performed at room temperature under magnetic stirring, under air atmosphere, of each complex ethanol solution and the ZHC solid support suspension. The materials obtained were characterized by X-ray powder diffraction (XRPD), ultraviolet- visible spectroscopy (UV–vis) (solid samples), Fourier transform infrared spectroscopy (FTIR) and electron paramagnetic resonance (EPR). The catalytic activity of the solids was investigated in cyclooctene, cyclo- hexane and n-heptane heterogeneous catalytic oxidation reactions with iodosylbenzene as the oxygen donor. The solid catalyst’s reutilization capacity was also investigated and the heterogeneous character of the catalytic process was confirmed. The compounds and the catalytic activity of FePor-ZHC were compared with the synthesis and catalytic activity of the same FePor immobilized on zinc hydroxide nitrate (ZHN). Though the matrixes are similar, the results obtained were exactly the opposite when the selectivity was analyzed. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Inspired by biological systems that have catalytic activity, many different compounds have been synthesized and investigated as oxidation catalysts [1–3]. In this context, synthetic metallopor- phyrins are investigated as mimics of cytochrome P-450 [2]. In live organisms the cytochrome P-450 performs oxidation reactions with high selectivity and efficiency [1]. Many different investi- gations involving metalloporphyrin catalytic activity have been performed, initially in homogeneous media (catalyst and sub- strate in the same solvent phase) [4–6]. Under these conditions, deactivation of the catalysts has been detected, for example, by dimerization or by destructive auto-oxidation. In the former pro- cess, two porphyrin-ring metal -oxo bridges are established and in the latter, active catalytic species approach other porphyrin molecule, deactivating both [7]. One of the most significant con- tributions to obtain efficient, selective and reusable catalysts using metalloporphyrins, seeking possible technological application, was the immobilization of porphyrinic compounds on solids such as clay minerals [7,8], silica [9], and other inorganic-supports [10]. ∗ Corresponding author. Tel.: +55 41 33613180; fax: +55 41 33613186. E-mail address: shirleyn@ufpr.br (S. Nakagaki). The strategy to obtain and use a solid catalyst for heterogeneous catalysis, where the catalytic species are immobilized, can hinder undesirable approximations between activated and non-activated catalytic species (this species can lead to a deactivating process caused by secondary reactions between porphyrinic rings [7]) and also can create materials that can be reused in several reaction cycles. In this context, the present work reports the study of a family of anionic iron(III) porphyrins (FePor) (Fig. 1), which were immobi- lized on zinc hydroxide chloride (ZHC), a non-exchangeable layered hydroxide salt [11]. Layered hydroxide salts have been studied for a great number of applications [11–13], such as intercalation reac- tions [14,15], catalyst support [12], oxide precursors [16,17], and others [11]. This class of compounds consists of modified brucite- like layers [12], where the Mg 2+ metallic center, surrounded by hydroxyl groups, is replaced by another M 2+ metallic center, such as Zn 2+ , Co 2+ or Cu 2+ [12,13]. Partial substitution of hydroxyl groups by other anions or water molecules creates a positive charge at the layers, which needs to be compensated by the presence of inter- layer anions. In the case of nitrate anions, the compound is an anionic exchanger and in the case of chloride, as these anions are grafted directly to the layers, the compound is neutral [11]. Specif- ically, zinc hydroxide chloride (ZHC) is represented by the formula Zn 5 (OH) 8 Cl 2 ·H 2 O [17,18] and the basic structural unit contains a vacancy in a quarter of the octahedral zinc sites coordinated to 0926-860X/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.apcata.2011.10.046