Approaches to Supramolecular Catalysis

Desolvation of the reacting polar groups is also a mechanism by which enzymes achieve rate accelerations. The desolvation of functional groups takes places during the inclusion of the reactants within the catalytic apparatus of the active site. This is another way of looking at the selective stabilization of the TS, in terms of a specific solvation of the reactants by the enzyme residues of the active site, which replaces the random solvation by the solvent molecules and the inherent enthalpic and entropic cost associated with their reorganization in the TS. 

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Controlled formation of three-dimensional functional devices in silica makes the hybrid membrane materials presented here of interest for the development of a new supramolecular approach to nanoscience and nanotechnology through self-organization, towards systems of increasing behavioral and functional addressabilities (catalysis, optical and electronic applications, etc.). 

In the present volume, our intention was to cover several modern approaches to phosphorus chemistry which were not, or at least not completely, covered in the previous volumes. The selected topics are expected to have broader relevance and to be interesting to a more general readership, since key aspects of phosphorus chemistry are pointed out. Indeed, several fields are investigated coordination chemistry, catalysis, supramolecular chemistry, biochemistry, hybrid organic-inorganic materials, new ambiphilic ligands, and biology. 

Breit, B. (2005) Supramolecular approaches to generate libraries of chelating bidentate ligands for homogeneous catalysis. Angeiv. Chem., Int. Ed.. 44, 6816-6825. 

Supramolecular Chemistry has been defined as the chemistry beyond the molecule. If you wish, any reaction, and especially catalysis, is a supramolecular phenomenon. The term supramolecular catalysis, however, is used in a much more narrow sense. A good approach to avoid endless discussions on definitions is to observe Mother Nature and look for supramolecular chemistry there. The molecular recognition of enzymes and their ability to catalyse numerous reactions with outstanding selectivities is a challenge for the (supramolecular) chemist. 

As enzymes encapsulate multiple functionalities within their catalytic cavity, they have also served as a major source of inspiration for the fields of biomimetic chemistry and supramolecular catalysis. Early mechanistic theories about how enzymes work have prompted scientists from various fields to explore similar approaches for synthetic systems. One of these approaches is host-guest catalysis, where one or more substrates are bound in a cavity next to the catalytically active site. 

Wang ZJ, et al. A supramolecular approach to combining enzymatic and transition metal catalysis. Nat Chem 2013 5 100-3. 

Several specific chemical approaches are used to achieve increased transition state binding. The organic approaches include, but are not limited to, changing solvation, proximity, nucleophilic activation, electrophilic activation, introducing strain, acid-base chemistry, covalent catalysis, and supramolecular chemistry. Additionally, in some of these approaches there is a change in mechanism to achieve catalysis. All these methods are discussed below. 

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