Solid-state assembly

Solid-state assemblies containing chalcophosphate anions, or their heavier group 15 analogues, are still relatively small in number compared to the well... 

Solid-state assemblies containing binary group 15/16 anions of the heavier pnictogens are also extremely well known, including the naturally occurring... 

Figure 4 Polychalcophosphate building blocks in solid-state assemblies (E = S, Se)...

The examples discussed above illustrate the importance of block copolymer chain segment incompatibilities for the phase separation of bulk materials, combined with the ability to perform chemistry within specific nanoscale domains to impose permanence upon those self-assembled nanostructured morphologies. Each is limited, however, to crosslinking of internal domains within the solid-state assemblies in order to create discrete nanoscale objects. To advance the level of control over regioselective crosslinking and offer methodologies that allow for the production of additional unique nanostructured materials, the pre-assembled structures can be produced in solution (Figure 6.4), as isolated islands with reactivity allowed either internally or on the external... 

Saadeh H, Wang L, Yu L. Supramolecular solid-state assemblies exhibiting electrooptic effects. J Am Chem Soc 2000 122 546-547. 

A heteromeric, as opposed to a homomeric, six-component solid-state assembly, of composition 2(thiodiglycolic acid) 4(isonicotinamde), has been described by Aakeroy et al. (Fig. 11).23 As in the case of 2(carboxylic acid) 2(amide), the central core was based on an amide dimer. The two diacids served as U-shaped units that forced two amide dimers to stack via hydrogen bonding to give the monocyclic structure. 

Fig. 31 The nine-component trigonal-prismatic solid-state assembly of 3(calix[4]arene derivative) 6(babituric acid) (a) plane of hydrogen-bonding and (b) perpendicular to hydrogenbonding.

Incorporation of Biocatalysts Into Synthetic Membranes. It Is generally accepted that only a few enzymes exist In vivo as a free protein In an aqueous medium, and that most of them either are bound to membranes or to solid-state assemblies or are present In a gel-llke surrounding. Enzymes attached to synthetic membrane matrices may serve as specific heterogeneous catalysts that can be used repeatedly. If they are sufficiently stable. In comparison to natural membranes, enzyme-bound synthetic membranes possess the advantage that they are mechanically more stable. 

Tlie sequential reactions in elongating acyl transfers in the synthesis of polyketide natural products and non-ribosomal peptide antibiotics such as erythromycin, rapamycin, epotliilone, lovastatin, penicillins, cyclosporin and vancomycin resemble molecular solid-state assembly lines. Such multimodular enzymes may be utilized in combinatorial biosynthesis by way of reprogramming for the manufacture of unnaUiral analogs of natural products. 

The most general approach to afford stable nanopartides via solid-state assembly relies on the use of block copolymers composed of a cross-linkable/gelable block and a soluble segment. The block polymer is cast from a good solvent for both blocks followed by annealing to yidd a segregated thin film in which mesostructures of the cross-linkable block are surrounded by a matrix of soluble block. When a diblock copolymer, A -b-Bm, is assembled in bulk, domains of B on the nano- or microscale distributed in a matrix of A will form... 

The LbL assembly of polymers to afford individiral nano-objects represents a imique synthetic methodology that combines features of solution- and solid-state assembly processes via selective interactions between polymers and preestablished templating substrates and, therefore, includes aspects of each of the typies of synthetic methods described in this chapter. The LbL terminology originates from the process, which involves alternating deposition of polymers and other components, having complementary functionalities to facilitate their attraction/adhesion, from solution onto a substrate to produce stable thin films. 

On the basis of the extensive structural data obtained from the CSD, it is obvious that in order to bring together two different discrete neutral molecular species into the same crystalline lattice, there should be some thermodynamically based reason (originating from a heteromeric molecular-recognition event) for the subsequent solid-state assembly. Although sfiay structures that cannot readily be explained within such a context will appear from time to time, there is no doubt that the overall structural trends, patterns of behavior, and reproducible motifs can be developed into reliable and versatile supramolecular synthetic strategies. 

Inside living cells, enzymes exist in an extremely structured environment, which may have the form of a gel, a membrane or other solid state assemblies. Under these conditions, the behavior of immobilized enzymes towards their inhibitors is very different from that in the homogeneous phase. The mode of enzymatic inhibition is variable from one inhibitor to another, and may also be reversible or irreversible. Inhibition may be observed with enzyme sensors without having to resort to techniques that require long extractions, such as dialysis or gel filtration, which are normally used to separate an inhibitor from a soluble enzyme. The response of the enzyme sensor provides a continuous measure of the activity of the immobilized enzyme, whether or not its inhibitor is present. Enzyme sensors thus allow convenient and rapid study of the inhibition of enzymes and their subsequent reactivation. 

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