Structure-catalytic function relationship of SiO(2)-Immobilized mononuclear cu complexes: An EPR study

 
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2007 (EN)
Structure-catalytic function relationship of SiO(2)-Immobilized mononuclear cu complexes: An EPR study (EN)

Grigoropoulou, G. (EN)

Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας (EL)
Grigoropoulou, G. (EN)

Mononuclear CuL and Cu(2L) complexes, where Lis propyl-thiazol-2-ylmetliylene-amine, covalently immobilized onto SiO(2), can catalyze efficiently the oxidation of 3,5-di-t-butylcatechol (DTBC) to 3,5-di-t-butylquinone (DTBQ) by utilizing ambient O(2) as oxidant. By increasing the loading of L on SiO(2), the DTBQ formation can be improved up to 400% vs the homogeneous catalyst. Equally important is however that grafting per se at low loading is not adequate for an improved catalytic activity. Appropriate loadings have to be achieved, which then may result in significant catalytic performance. Based on EPR spectroscopy a theoretical method is developed, eq A 12, for spin-spin distance estimation in heterogeneously dispersed surface complexes. Practical rules including error estimates are provided. By applying this method to the [SiO(2)-CuL] catalysts it is shown that mononuclear copper complexes fixed On SiO(2) With Cu center dot center dot center dot Cu distances as short as 4.9 +/- 0.3 angstrom are responsible for the improved catalytic activity. The present results demonstrate that mononuclear Cu complexes can have considerable catecholase activity, if the proper geometrical proximity can be fixed. Grafting on SiO(2) may be an efficient method for engineering catalysts with improved performance. (EN)

dinuclear copper(ii) complexes (EN)

Πανεπιστήμιο Ιωαννίνων (EL)
University of Ioannina (EN)

Langmuir (EN)

English

2007

<Go to ISI>://000249560100066

American Chemical Society (EN)



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