Nanoreactors, self-assembled

Among various types of nanoreactors, self-assembled capsules have proven their use as catalysts of wide range of reactions [3]. Self-assembled capsules can be obtained through hydrogen bonding or metal-hgand interactions [1]. 

Out of these assemblies, microemulsion droplets and swollen micelles have been widely used as nanoreactors for inorganic nanoparticie synthesis [20-23]. These self-assembled nanosized beakers/droplets provide a robust and tunable environment that permits size-controlled encapsulation of... 

Vnezema DM, Aragones MC, Elemans JAAW, Comelissen JJLM, Rowan AE, Nolte RJM (2005) Self-assembled nanoreactors. Chem Rev 105 1445... 

Later, more sophisticated supramolecular complexes capable of improved molecular recognition started to be studied. New supramolecular approaches to constmct synthetic biohybrid catalysts were developed [190]. An example is the giant amphi-philes, formed by a (hydrophilic) enzyme headgroup and a synthetic apolar tail. These biohybrid amphiphilic compounds self-assemble in water to yield enzyme fibers and enzyme reaction vessels (nanoreactors [202]). 

Keywords Amphiphilic block copolymers, Membranes, Nanoreactors, Polymer-somes, Self-assembly, Stimuli-responsive vesicles... 

This book can be considered a third edition since there was an earlier book. Chemical Reactor Design, John Wiley Sons, 1987, that was followed by the first edition bearing the current title. The new title reflected an emphasis on optimization and particularly on scaleup, a topic rarely covered in detail in undergraduate or graduate education but of paramount importance to many practicing engineers. The treatment of biochemical and polymer reaction engineering is also more extensive than normal. There is a completely new chapter on meso-, micro-, and nanoreactors that includes such topics as axial diffusion in microreactors and self-assembly of nanostructures. 

One dimensional arrays of mesoscopic tunnel junctions, built up from clusters, have been treated theoretically (see also Section 4.4.3.2). There are different means of arranging clusters in one dimension, e.g. inclusion into ID channel structures, connection to rod-like molecules, such as DNA strands,or deposition on to preformed substrates. The preparation techniques will cover a broad field ranging from self-assembly or LB techniques, through nanoreactor synthesis, up to electrodeposition. 

Since the nineties of the last century, research groups around the world have explored the application of nanocapsules as nanoreactors, i.e. reaction vessels for chemical transformations, and the influence of different cavity effects." In this chapter the focus will mainly be on recent developments concerned with synthetic nanoreactors that can be obtained in a selective and controlled manner through the use of self-assembly principles and rational design, and on their application as catalytically active capsules for respective chemical reactions. For the sake of clarity, each specific type of nanoreactor will be discussed in a separate section. Particular types of nanocapsules to be reviewed include assemblies held together by hydrogen bonding, metal-ligand interactions and hydrophobic... 

Snbseqnent work has established the formation of chiral derivatives of nanoreactor D throngh the nse of chiral diamine end-capping gronps instead of ethylenediamine as ligand on the Pd bnilding blocks and snbseqnent self-assembly with functionalized triazine frameworks. These chiral nanocages are able to remotely control the chiral [2h-2] photo addition of flnoranthenes and several maleimides, a reaction previously unknown to be performed in an asymmetric fashion, in np to 50% ee." ... 

In addition to the nanoreactors discussed in this review, which are formed by assembly of at least two building blocks, capsules based on covalent bonds have also been applied as nanoreactors." Such covalent nanoreactors were beyond the scope of the current review, but similar effects in catalysis are observed. However, self-assembled capsules also have guest exchange mechanisms via partial disassembly of the capsule, whereas exchange for the covalent analogues is restricted to portal slippage. It is this unique property that enables the combination of complete encapsulation with sufficiently rapid... 

Although the research field is still in its infancy, several examples of reactions, wherein self-assembled nanoreactors are applied and are shown to dramatic enhance or alter reactivity, have appeared, thereby demonstrating the power of the supramolecular concept. Detailed studies are required to fully understand the mechanisms behind the effects observed when carrying out reactions in nanoreactors. The results obtained so far sketch a bright prospective, as reactions have been observed that are unique to those carried out in capsules. In this review we have focussed on reactions that take place inside the capsules. However, molecular capsules have also been used to control reactions that take place outside the capsule for example by controlling the release of reagents, making the nanoreactor applications virtually unlimited. ... 

A. D. Crespy, M. Stark, C. Hoffmann-Richter, U. Ziener, K. Landfester, Polymeric nanoreactors for hydrophilic reagents synthesized by interfacial polycondensation on miniemulsion droplets. Macromolecules, 2007, 40, 3122 b) O. Gazit, R. Khalfln, Y. Cohen, R. Tannenbaum, Self-assembled diblock copolymer nanoreactors as catalysts for metal nanoparticle synthesis, J. Phys. Chem. C, 2009, 113, 576. 

B. M. Rossbach, K. Leopold, R. Weberskirch, Self-assembled nanoreactors as highly active catalysts in the hydrolytic kinetic resolution (HKR) of epoxides in water, Angew. Chem. Int. Ed, 2006, 45, 1309. 

The current interest in the self-assembly of polymeric systems on surfaces stems from the many opportunities that these assemblies present for the preparation of novel functional nanomaterials, i.e., for drug delivery, in catalysis and nanoreactor technology, and for molecular templating. The interesting aspect of these systems is that their properties and structure can be manipulated by a number of parameters such as a) chemical structure, composition, and architecture, b) preparation methods and microengineering techniques used, and c) nature and properties of the underlying substrate and its interactions with the polymer chains [1-5]. 

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