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Über dieses Buch

Molecular Cages and Capsules with Functionalized Inner Surfaces, by Stefan Kubik. Drug Delivery by Water-Soluble Organ metallic Cages, by Bruno Therrien. Reversibly Expanded Encapsulation Complexes, by Dariush Ajami und Julius Rebek. Container Molecules Based on Imine Type Ligands, by A. Carina Schulze und Iris M. Oppel. Molecular Capsules Derived from Resorcin[4]arenes by Metal-Coordination, by Tobias Schröder, Satya Narayan Sahu und Jochen Mattay. Coronates, Spherical Containers, Bowl-Shaped Surfaces, Porous 1D-, 2D-, 3D-Metallo-Coordination Polymers, and Metallodendrimers, by Rolf W. Saalfrank und Andreas Scheurer.



Molecular Cages and Capsules with Functionalized Inner Surfaces

Molecular containers enclose a well defined cavity in which an appropriate guest molecule can be included. The corresponding complexes are generally characterized by high kinetic stability. Thermodynamic stability can be rather low, however, because attractive interactions are largely missing between host and guest causing binding to be mainly due to entropic factors. This situation can be improved by distributing appropriate binding sites across the inner surface of a molecular container to which an included guest can bind. This approach, while being conceptually simple, is not straightforward since the incorporation of converging binding sites into a concave surface is difficult and usually requires receptors architectures that differ from those of conventional covalently assembled molecular containers. Therefore, the term molecular cage rather than molecular container is often more appropriate for such types of receptors. In this overview, a selection of cage-type receptors is presented whose inner cavity is functionalized with groups that can engage in directed interactions with an included guest. These receptors, classified according to the type of interaction responsible for guest binding, were chosen to illustrate effects of the inwardly directed binding sites on receptor affinity, selectivity, or other binding properties.
Graphical Abstract
Stefan Kubik

Drug Delivery by Water-Soluble Organometallic Cages

Until recently, organometallic derivatives were generally viewed as moisture- and air-sensitive compounds, and consequently very challenging to synthesise and very demanding in terms of laboratory requirements (Schlenk techniques, dried solvent, glove box). However, an increasing number of stable, water-soluble organometallic compounds are now available, and organometallic chemistry in aqueous phase is a flourishing area of research. As such, coordination-driven self-assemblies using organometallic building blocks are compatible with water, thus opening new perspectives in bio-organometallic chemistry.
This chapter gives a short history of coordination-driven self-assembly, with a special attention to organometallic metalla-cycles, especially those composed of half-sandwich complexes. These metalla-assemblies have been used as sensors, as anticancer agents, as well as drug carriers.
Bruno Therrien

Reversibly Expanded Encapsulation Complexes

Synthetic receptors that surround their target molecules – self assembled capsules and deep cavitands – have emerged as the most realistic models of enzymes active sites. They were introduced to study the behaviour of molecules isolated in small spaces and it has become increasingly clear that the behavior of molecules in dilute aqueous solution does not reflect their behavior in confimed spaces. The synthetic receptors fold around their target guests, isolate them from the bulk solvent, provide a hydrophobic environment and present the guests with each other in a limited space. These features combine to show high binding selectivity, large rate from the ground up; they are designed, synthesized then tested. In recent years, we have found a short-cut to total synthesis; some capsules readily insert spacer elements in the presence of suitable guests that fill the enlarged spaces. This expands the repertoire of containers and the present review describes their structures, the nature of the spaces inside, the exchange dynamics, and the rules that govern their formation.
Dariush Ajami, Julius Rebek

Container Molecules Based on Imine Type Ligands

This chapter will give a short overview about container molecules, their synthesis and possible applications. The main focus is on those which are based on imine type ligands. These containers can be used for example for guest exchange, gas separation, as chemical sensors or for the stabilisation of white phosphorus under water. The described cages have wide openings or tightly closed ones. For one cage the reversible opening and closing is also described.
A. Carina Schulze, Iris M. Oppel

Molecular Capsules Derived from Resorcin[4]arenes by Metal-Coordination

A short introduction to the fundamental features and recent developments of supramolecular chemistry is presented besides defining scope and limitation of this review article. A brief overview about calix[n]arenes and especially resorcin[4]arenes and their conformationally rigid cavitands is given. Selected examples are presented to demonstrate the dependence of self-assembly of cavitands exhibiting different flexibility either due to their basic macrocycle or due to flexible receptor units commonly located at the o,o′-position of the resorcinarene ring. In addition, the process of self-assembly is also controlled by metal coordination geometry as shown by one example. The receptor units may also be connected at the methylene group of the cavitand as shown by one example. Examples of supramolecular architectures are presented utilizing the special features of 2,2′:6′,2″-terpyridine (terpy) metal-binding ligand. The synthesis and characterization of a metallo-supramolecular Zn-coordination cage with a diameter of 4–5nm based on a cavitand-terpy building block is presented in detail.
Tobias Schröder, Satya Narayan Sahu, Jochen Mattay

Coronates, Spherical Containers, Bowl-Shaped Surfaces, Porous 1D-, 2D-, 3D-Metallo-Coordination Polymers, and Metallodendrimers

Supramolecular coordination cages and polymers bear exceptional advantages over their organic counterparts. They are available in one-pot reactions and in high yields and display physical properties that are generally inaccessible with organic species. Moreover, their weak, reversible, noncovalent bonding interactions facilitate error checking and self-correction. This review emphasizes the achievements in supramolecular coordination container as well as polymer chemistry initiated by serendipity and their materialization based on rational design. The recognition of similarities in the synthesis of different supramolecular assemblies allows prediction of potential structures in related cases. The combination of detailed symmetry considerations with the basic rules of coordination chemistry has only recently allowed for the design of rational strategies for the construction of a variety of nanosized spherical containers, bowls, 1D-, 2D-, and 3D-coordination polymers with specified size and shape.
Rolf W. Saalfrank, Andreas Scheurer


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