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Copper(II)–Purine Complexes Encapsulated in NaY Zeolite
Author(s) -
Nunes Natércia,
Amaro Raquel,
Costa Filomena,
Rombi Elisabetta,
Carvalho M. Alice,
Neves Isabel C.,
Fonseca António M.
Publication year - 2007
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200601036
Subject(s) - chemistry , cyclohexene , catalysis , copper , aqueous solution , stoichiometry , zeolite , inorganic chemistry , metal , cyclohexene oxide , electron paramagnetic resonance , peroxide , nuclear chemistry , polymer chemistry , organic chemistry , physics , nuclear magnetic resonance
Y‐encapsulated Cu II –purine complexes were synthesized, characterized and studied in the catalytic oxidation of cyclohexene. Encapsulation was achieved by ion‐exchanging the complex from aqueous solutions containing both the purine ligand, 9‐methyl‐6‐(methylamino)purine, and copper, in different pH, with a purine/Cu II molar ratio of 5:1. The resulting materials were characterized by surface analysis (XPS, SEM and XRD), chemical analysis, spectroscopic methods (EPR, FTIR and UV/Vis) and thermal analysis (TGA), which indicated that the Cu II –purine complexes were effectively encapsulated in NaY, most probably inside the supercages, without any modification of the morphology and structure of the zeolite. Different Cu II –purine complexes were formed, depending on the pH during synthesis. The coordination geometry of Y‐encapsulated Cu II –purine complexes was obtained with preferentially 1:2 and 1:3 Cu/L stoichiometry: complexes A and B (1:2) and complex C (1:3). Complex A was formed at pH ≥ 7, and complexes B and C (Scheme 2) were formed at pH = 5.4. Oxidation of cyclohexene with t BuOOH (TBHP) as the oxygen source, gave 2‐cyclohexene‐1‐one, 2‐cyclohexene‐1‐ol, cyclohexene oxide and 3‐ tert ‐butylcyclohexenyl peroxide. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)