Micelles metallomicelles

The modulation of the coordination to the transition metal has not necessarily positive implications on the reactivity. For instance, we observed [50] that the copper(II) complex (8) of tetramethyl-l,2-diaminoethane catalyzes the hydrolysis of the phosphoric acid triester PNPDPP via an electrophilic mechanism which involves the pseudointramolecular attack of deprotonated water, as illustrated in (9). The electrophilic mechanism contribution to the hydrolytic process totally disappears in micellar aggregates made of the amphiphilic complex (10). Clearly, micellization does not allow the P O group of the substrate to interact with the metal ion. This could be a result of steric constraint of the substrate when bound to the micelle and/or the formation of binuclear dihydroxy complexes, like (11), in the aggregate. So, in spite of the quite large rate accelerations observed [51] in the cleavage of PNPDPP in metallomicelles made of the amphiphilic complex (10), the second-order rate constant [allowing for the difference in pXa of the H2O molecules bound to copper(II) in micelles and monomers] is higher for (8) than for (10) (k > 250). 

It has been suggested that significant enhancement of the epimerization was due to the formation of metallomicelles in the reaction system. To confirm the existence of the micelles, the surface tension of the reaction system was measured. It was confirmed that hydrophobic Ni/diamine complexes containing alkyl chains longer than decyl form micelles, whereas Ni/diamine complexes containing alkyl chains shorter than nonyl do not. It should be emphasized that such formation of micelles was in accordance with the occurrence of epimerization. The fact that a nickel complex that can aggregate to form metallomicelles shows excellent epimerizing ability is the most noteworthy point. 

Unlike metallomicelles, fnnctional surfactant micelles compared to nonfunctional snrfactant micelles exhibit rate enhancement of many orders. The reason for snch apparent characteristic difference between the catalytic efficiency of metallomicelles and functional snrfactant micelles is the choice of the reference reactions nsed to evaluate the catalytic efficiency of metallomicelles and func-... 

The studies on the effects of micelles and mixed micelles on the rate of metal ion-ligand complex formation (i.e., the rate of inorganic reactions), as well as the effects of metallomicelles and induced functional metallomicelles on the rate of organic reactions have been carried out extensively during the last nearly five decades. Induced functional metallomicelles are expected to provide impressive... 

The book first discusses the structural and chemical properties of micelles and the role of thennodynamics, concentration, and additives in fonning micelles. Demonstrating how intcrmolecular forces influence the reaction mechanisms, the author presents kinetic models for reactions catalyzed by normal micelles, as well as mixed micelles and metallomicelles. The book also compares various types of catalytic reactions with and without micelles to quantify their effect on reaction rates and rate constants. Using this information, it illustrates how micelles can modify reaction rates and improve catalytic efficiency, particularly for industrial processes. The final chapter explains the principles of kinetics used for data analysis. 

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