Three-dimensional assemblies

Metal-acetylide complexes including metal-poly(yne) polymers often show unique properties [21-23]. Thus, metal-acetylide dendrimers are of interest because amplification of the functionality due to metal-acetylide units based on three-dimensional assembly with a regular dendritic structure is expected. 

Two reviews5,6 with approximately 34 references discuss a coordination approach to three-dimensional assemblies via molecular paneling. Families of planar exo-multidentate organic ligands (molecular panels) assemble into large three-dimensional assemblies through metal-coordination. In particular, m-protected square planar metals, (en)Pd2+ or (en)Pt2+ (en = ethylene-1,2-diamine), are very useful to panel the molecules. Metal-assembled cages, bowls, tubes, capsules, and polyhedra are efficiently constructed by this approach. 

Due to the inherent stiffness of 1,4-phenylene based polymers and based on molecular modeUng calculations (see below), the question arises whether the shape of the dendrimer can be predetermined by choosing an appropriate core. This should be important for the use of dendrimers in single molecule appHca-tions, as carriers for dyes for single molecule optical spectroscopy or as building blocks for two- and three-dimensional assemblies. There are two possibiHties variation of the core and variation of the building unit. Therefore, we synthesized dendrimers based on cores with different symmetries presented in Scheme 4. 

We further addressed the use of the nucleic acids as biopolymers for the formation of supramolecular structures that enable the electronic or electrochemical detection of DNA. Specifically, we discussed the use of aptamer/low-molecular-weight molecules or aptamer/protein supramolecular complexes for the electrical analysis of the guest substrates in these complexes. Also, nucleic acid-NPs hybrid systems hold a great promise as sensing matrices for the electrical detection of DNA in composite three-dimensional assemblies. While sensitive and selective electrochemical sensors for DNA were fabricated, the integration of these sensor configurations in array formats (DNA chips) for the multiplexed analysis of many DNAs can also be envisaged. 

Fig. 4 Inorganic three-dimensional assemblies using octahedral metal ions, [Gadisophthal-di-iV-(4-methylphenyl)hydroxamate 6] (a) [12] and [ Rh2(DAniF)2(CH3CN) 4(calix[4]arenetetra-carboxylinato)2] (b) [13]...

These examples illustrate the versatility of half-sandwich complexes in the construction of two- and three-dimensional assemblies, thus providing a multitude of possibilities for producing new metalla-hosts for various applications. 

A lateral penetration of the entire lipo-peptide molecule. i.e. including the lipid tail, is difficult to rationalize as the helix boundle of the receptor represents a tight assembly which precludes diffusion of membrane lipids into its core structure in order to maintain its three-dimensional assembly Consequently, it should therefore preclude also a penetration of the lipo-tail of DM-gastrin and DM-CCK, and the lipo-peptides should approach the receptor with the tail inserted Into the lipid bilayer and then protrude into the binding deft across the extracellular loops. 

In hexagonal mesoporous SBA-15, straight mesopores are connected three-dimensionally by some microporous bridges. Therefore, a three-dimensional assembly of nanowires with bridges can be obtained from the SBA-15 template. 

The field of supramolecular chemistry is concerned with a large number of systems ranging from simple host-guest complexes to more complicated solution assemblies, as well as two-dimensional (organized monolayers) and three-dimensional assemblies (crystalline solids). Nonco-valent interactions play an important role in the kinetic assembly and thermodynamic stabilization of all these systems and constitute their most distinctive feature. Electron-transfer reactions can obviously be affected by supramolecular structures, but the reverse is also true. It is possible to alter the structure and the thermodynamic stability of supramolecular assemblies using electrochemical (redox) conversions. In other words, electron-transfer reactions can be utilized to exert some degree of control on supramolecular aggregates. Provided in this article is an overview of the interplay between supramolecular structure and electron-transfer reactions. 

Aerogels are quasi-stable, low-density, three-dimensional assemblies of nanoparticles, which have usually poor mechanical properties. A facile one-pot synthesis of Kevlar-like aerogels based on the reaction of multifunctional isocyanates and carboxylic acids has been reported [57]. The materials exhibit an ultimate compressive strength, a high specific energy absorption, and a thermal conductivity like foamed PS. By a pyrolysis process at 800 °C, the materials can be converted to a porous, electrically conducting carbon with a high surface area. 

The fourth dassiiication scheme has been used by Cifetri, differentiating SPs on the basis of the physical stmcture assumed through polymerization. Example classes indude linear chains, helical chains, columnar assemblies, micdlar assemblies, planar assemblies, composite assemblies, and three-dimensional assemblies. Ciferri induded a breakdown and description of the linear and hdical chain assemblies as being controlled by different growth mechanisms however, these types are ultimatdy dassified by resulting stmcture. 

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