Supramolecular solids, layered

Channel Inclusion Compounds, p. 223 Isostructurality of Inclusion Compounds, p. 767 Layered Supramolecular Solids and Their Intercalates, p. 791... 

Inokuma et al have reported a further example of additions with crown ether derivatives. In this instance the additions are intermolecular and involve the dimerization of the vinylbenzene derivative (123) to afford the two adducts (124) and (125). The ion-complexing capabilities of the adducts were assessed. A layered ternary solid is formed between 1,2-dihydroxybenzene and trans- -(2-pyridyl)-2-(4-pyridyl)ethylene. Within this, the stilbene is held in a head-to-tail arrangement. Irradiation brings about the formation of a cyclobutane identified as (i )-c/ y,/ra y,/ra -l,3-bis(2-pyridyl)-2,4-bis(4-pyridyl)cyclobutane. An extension of this work to the use of 5-methoxyresorcinol as the template has demonstrated that quantitative yields of ladderanes (126) can be obtained by irradiation of the solid-state units represented as (127). The diazastilbene derivative (128) readily forms complexes with the tetra-acid (129). This acts as a supramolecular template and holds the ethene systems close enough for photochemical dimerization. ... 

In this chapter we describe the basic principles involved in the controlled production and modification of two-dimensional protein crystals. These are synthesized in nature as the outermost cell surface layer (S-layer) of prokaryotic organisms and have been successfully applied as basic building blocks in a biomolecular construction kit. Most importantly, the constituent subunits of the S-layer lattices have the capability to recrystallize into iso-porous closed monolayers in suspension, at liquid-surface interfaces, on lipid films, on liposomes, and on solid supports (e.g., silicon wafers, metals, and polymers). The self-assembled monomolecular lattices have been utilized for the immobilization of functional biomolecules in an ordered fashion and for their controlled confinement in defined areas of nanometer dimension. Thus, S-layers fulfill key requirements for the development of new supramolecular materials and enable the design of a broad spectrum of nanoscale devices, as required in molecular nanotechnology, nanobiotechnology, and biomimetics [1-3]. 

Successive H-bond urea self-assembly of 4 and sol-gel transcription steps yield preferential conduction pathways within the hybrid membrane materials. Crystallographic, microscopic and transport data confirm the formation of self-organized molecular channels transcribed in solid dense thin-layer membranes. The ionic transport across the organized domains illustrates the power of the supramolecular approach for the design of continual hydrophilic transport devices in hybrid membrane materials by self-organization (Figure 10.8) [42-44]. 

A second class of monolayers based on van der Waal s interactions within the monolayer and chemisorption (in contrast with physisorption in the case of LB films) on a solid substrate are self-assembled monolayers (SAMs). SAMs are well-ordered layers, one molecule thick, that form spontaneously by the reaction of molecules, typically substituted-alkyl chains, with the surface of solid materials (193—195). A wide variety of SAM-based supramolecular structures have been generated and used as functional components of materials systems in a wide range of technological applications ranging from nanolithography (196,197) to chemical sensing (198—201). 

As pointed out in Chapter 1, supramolecular chemistry comprises two broad, partially overlapping areas covering on the one hand the oligomolecular supermolecules and, on the other, the supramolecular assemblies, extended polymolecular arrays presenting a more or less well-defined microscopic organisation and macroscopic features depending on their nature (layers, films, membranes, vesicles, micelles, microemulsions, gels, mesomorphic phases, solid state species, etc.). 

The term modified electrodes encompasses a broad variety of electrode materials obtained by attaching a monomolecular layer of a specific compound on the surface of a conducting solid [338]. In electrocatalysis, modified electrodes are common in the field of oxygen reduction, where carbon materials can be modified for example by attaching layers of macrocycles. Modified electrodes are very common in the field of molecular or supramolecular electrochemistry, especially in the organic area. 

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