Self-Organization in Coordination-Driven Self-Assembly

Abstract

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...

A ferrocene-based catecholamide ligand: the consequences of ligand swivel for directed supramolecular self-assembly

“…The [Ge 2 L 3 ] stoichiometry suggests formation of a triple-stranded metallohelicate or mesocate. While it is possible that the major species observed by 1 Figure 4a is the metallohelicate or mesocate, since mass spectrometry does not provide information about molecular structure or the relative amounts of species in solution, this remains uncertain. Figure 4a is diluted with CD 3 OD, a new complex, with the same ligand symmetry as the major species in Figure 4a, is rapidly and quantitatively formed (Figure 4b).…”

“…One common approach to the design and synthesis of such assemblies is the use of labile, metal-ligand interactions. Appropriately chosen ligand symmetries and incommensurate coordination numbers between ligand and metal can be used to direct the reversible self-assembly of complex supramolecular architectures [1][2][3][4][5]. This strategy has allowed the preparation of many metalligand based supramolecular structures such as rotaxanes and catenanes [6][7][8], helicates [9][10][11] and molecular squares, rings, grids and polyhedra [12][13][14][15][16][17][18].…”

Photoinduced transformations of stiff-stilbene-based discrete metallacycles to metallosupramolecular polymers

“…Yang and coworkers (8) reported hydrogen-bonded supramolecular polymers and studied their polymerization mechanisms and physical properties based on the photoisomerization of the stiff-stilbene units. Nevertheless, stiff-stilbene-based supramolecular entities are underexplored despite exhibiting properties that make the functionality potentially useful in the construction of photoresponsive supramolecular materials.Coordination-driven self-assembly is a powerful method of constructing supramolecular coordination complexes (SCCs) by the spontaneous formation of metal-ligand bonds that draws inspiration from the design principles of natural systems (9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). This approach organizes metal acceptors and organic donors to prepare well-defined cavity-cored 2D metallacycles and 3D metallacages, which can be functionalized on their interior or exterior vertices for applications in host-guest chemistry (21, 22), catalysis (23), molecular flasks (24), bioengineering (25), amphiphilic self-assembly (26), and so on.…”

“…Coordination-driven self-assembly is a powerful method of constructing supramolecular coordination complexes (SCCs) by the spontaneous formation of metal-ligand bonds that draws inspiration from the design principles of natural systems (9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). This approach organizes metal acceptors and organic donors to prepare well-defined cavity-cored 2D metallacycles and 3D metallacages, which can be functionalized on their interior or exterior vertices for applications in host-guest chemistry (21,22), catalysis (23), molecular flasks (24), bioengineering (25), amphiphilic self-assembly (26), and so on.…”

Supramolecular polymers with tunable topologies via hierarchical coordination-driven self-assembly and hydrogen bonding interfaces

“…Metal-ligand bonding has proven to be a particularly valuable method to guide the organization of molecular precursors through strategies such as coordination-driven self-assembly (21)(22)(23)(24)(25)(26). By carefully combining selected building blocks, discrete supramolecular coordination complexes (SCCs) can be obtained (27)(28)(29)(30)(31), based on the number and orientation of the labile coordination sites (for metal acceptors) and Lewis basic moieties (for organic donors).…”