ConspectusSelf-assembly allows for the preparation of highly complex molecular and supramolecular systems from relatively simple starting materials. Typically, self-assembled supramolecules are constructed by combining complementary pairs of two highly symmetric molecular components, thus limiting the chances of forming unwanted side products. Combining asymmetric molecular components or multiple complementary sets of molecules in one complex mixture can produce myriad different ordered and disordered supramolecular assemblies. Alternatively, spontaneous self-organization phenomena can promote the formation of specific product(s) out of a collection of multiple possibilities. Self-organization processes are common throughout much of nature and are especially common in biological systems. Recently, researchers have studied self-organized self-assembly in purely synthetic systems.This Account describes our investigations of self-organization in the coordination-driven selfassembly of platinum(II)-based metallosupramolecules. The modularity of the coordination-driven approach to self-assembly has allowed us to systematically study a wide variety of different factors that can control the extent of supramolecular self-organization. In particular, we have evaluated the effects of the symmetry and polarity of ambidentate donor subunits, differences in geometrical parameters (e.g. the size, angularity, and dimensionality) of Pt(II)-based acceptors and organic donors, the influence of temperature and solvent, and the effects of intermolecular steric interactions and hydrophobic interactions on self-organization.Our studies have shown that the extent of self-organization in the coordination-driven self-assembly of both 2D polygons and 3D polyhedra ranges from no organization (a statistical mixture of multiple products), to amplified organization (wherein a particular product or products are favored over others), and all the way to the absolute self-organization of discrete supramolecular assemblies. In many cases, inputs such as dipolar interactions, steric interactions, and differences in the geometric parameters of subunits-used either alone or as multiple factors simultaneously-can achieve absolute self-organization of discrete supramolecules. We have also observed instances where selforganization is not absolute and varies in its deviation from statistical results. Steric interactions are particularly useful control factors for driving such amplified self-organization because they can be subtly tuned through small structural variations.Having the ability to fully understand and control the self-organization of complex mixtures into specific synthetic supramolecules can provide a better understanding of analogous processes in biological systems. Furthermore, self-organization may allow for the facile synthesis of complex multifunctional, multicomponent systems from simply mixing a collection of much simpler, judiciously designed individual molecular components.stang@chem.utah.edu. NIH Public Access IntroductionChemist...

Conspectus Coordination-driven self-assembly utilizes the spontaneous formation of metal-ligand bonds in solution to drive mixtures of molecular building blocks to single, unique 2D metallacycles or 3D metallacages based on the directionality of the precursors used. The supramolecular coordination complexes (SCCs) obtained via this process are characterized by well-defined internal cavities and facile pre- or post-self-assembly functionalizations. These properties augment the modularity of the directional bonding design strategy to afford structures with unprecedented tunability both spatially and electronically. Over the past decades, a number of synthetic design methodologies have become established which has led to a substantial library of complexes supported by numerous structural studies. More recently, there has been an emergence of research centered on the potential applications of SCCs, which has developed rapidly on the foundations provided by the aforementioned synthetic and structural bodies of work. The necessary presence of metal ions as structural elements for the directional bonding approach can be exploited to provide biological activity to an SCC, particularly for Pt and Ru-based structures. Since these two metals are not only among the most commonly used for coordination-driven self-assembly but are also the basis for a number of small molecule anticancer agents, a growing number of SCCs have been evaluated for their antitumor properties. When the internal cavity of a cage is optimized for guest encapsulation, a second vector for biological activity, namely drug delivery, is unlocked. Since cages can offer both inherent activity due to their metal ions, as well as delivery of exogenous drug molecules, such ensembles are particularly promising chemotherapeutic agents. The non-covalent interactions of SCCs with guest molecules oftentimes manifest photophysical changes to the resulting host/guest complex. Since a metallacage or cycle can be readily tuned to match a specific guest, certain SCCs are well-suited to act as fluorescence-based sensors for biologically relevant analytes. These interactions are not limited to small molecule analytes, however, and SCCs are increasingly being studied for their chemistry with macro biomolecules including DNA and proteins. In particular, dinuclear iron and ruthenium-based helicates bind to a variety of DNA constructs through non-covalent mechanisms. Studies concerning these cylindrical SCCs, which have expanded beyond Ru and Fe, often include characterizations of specific interactions with DNA or other biomolecules. Such investigations are not limited to dinuclear M2L3 helicates; Pt-based squares are well-suited to stabilize G-quadruplex DNA and rhomboid metallacycles can unravel supercoiled DNA, further demonstrating the versatility of multinuclear supramolecular architectures. Understanding these interactions in the context of observed cytotoxicities and other biological consequences is critical for developing new chemotherapeutic agents and developing mech...

A new, simple, and effective method for the diazotization of a wide range of arylamines has been developed by using a polymer-supported diazotization agent in the presence of p-toluenesulfonic acid. Various pure arenediazonium tosylates with unusual stabilities can be easily prepared by this method. As a result, these salts are useful and versatile substrates for subsequent transformations, such as halogenation and Heck-type reactions. The unusual stabilities of arenediazonium tosylates are also preliminarily discussed with their X-ray structures.