Finite molecular assemblies in the organic

Finite molecular assemblies in the organic solid state toward engineering properties of solids, 40, 109... 

It is with these ideas in mind that we focus here on the design and construction of finite molecular assemblies in the organic solid state. Our intention is to provide an overview of finite assemblies with emphasis on properties that such assemblies may provide solids. We will begin by outlining general criteria for constructing finite molecular assemblies in both the solid state and solution, and then describe assemblies isolated and characterized in the solid state to date. We will then use recent advances in our laboratory to illustrate how finite assemblies can be used to control solid-state reactivity and direct the synthesis of molecules. 

The molecular assemblies described above have inspired us, in recent years, to develop finite assemblies in the solid state that exhibit chemical reactivity. Specifically, we,69 and others,70 have been utilizing principles of molecular recognition and self-assembly to develop a method to direct the formation of covalent bonds in organic solids. The method builds on the work of Schmidt on the reactivity of cinnamic acids in the organic solid state.45 Specifically, Schmidt has described topochemical postulates that dictate geometry criteria for a [2 + 2] photodimerization to occur in a solid. The postulates state that two carbon-carbon double (C=C) bonds should be aligned in parallel and separated by a distance <4.2 A to react. 

The general field with which this review is concerned is currently one of the most exciting in chemical physics, the study of kinetic processes in systems of finite size and/or of restricted dimensionality. Problems ranging from the study of organized molecular assemblies (micelles, vesicles, microemulsions), biological systems (cells, microtubules, chloroplasts, mitochondria), structured media such as clays and zeolites, and nucleation phenomena in finite domains are among those under active investigation. 

The different types of polycatenated species can be enumerated and classified on the basis of the increasing dimensionality of the component motifs (OD, ID or 2D) [3]. Finite (OD) motifs, containing closed circuits, can give, in principle, catenation into infinite periodic arrays (from ID up to 3D), though no real example has as yet been characterized. Examples of polycatenated species containing many molecular rings have been described within complex organic species [54], proteins [66] and synthetic DNA assemblies [67]. 

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