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

Abstract

A powerful strategy to obtain complex supramolecular materials is the bottom-up construction of noncovalently bound materials by hierarchical self-assembly. This assembly process involves stepwise, uniform increases to the architectural complexity of a substrate, starting from discrete precursors and growing in dimensionality through controlled reactivity to a final product. Herein, two orthogonal processes are exploited: coordination-driven self-assembly and hydrogen bonding. The former relies on the predictable formation of metal-ligand bonds wherein the directionalities of the rigid precursors used determines the structural outcome. The latter uses 2-ureido-4-pyrimidinone interfaces that are structurally robust by virtue of the quadruple hydrogen bonding that can occur between subunits. By combining these two processes into a single system, it is possible to generate hierarchical materials that preserve the attractive tunability associated with discrete supramolecular coordination complexes. For instance, the synthesis of a one-dimensional chain comprising linked metalla-rhomboids is readily adapted to a 2D cross-linked hexagonal network by simply selecting a different metal acceptor precursor as an assembly component. The specific interactions between subunits, in this case platinum(II)-pyridyl bonds and the quadruple H-bonding of ureidopyrimidinone, are unchanged, establishing a unique strategy to obtain supramolecular polymers with marked topological differences with minimal synthetic redesign. In addition, the structural rigidity imposed by the inclusion of the platinum metallacycles serves to minimize the formation of cyclic oligomers, increasing the efficacy of formation and improving the properties of the resultant materials. Furthermore, this study taps the potential of organoplatinum(II) metallacycles in materials science.

Computational Discovery of Hydrogen Bond Design Rules for Electrochemical Ion Separation

“…Strong, directional hydrogen bonding is a key paradigm in selective anion recognition 12,[24][25][26][27] , catalysis [28][29][30][31][32] , drug design [33][34][35][36] and materials design [37][38][39] . In anion recognition in particular, HB donors distributed uniformly around a cavity of desired size 12,24,[40][41] have been shown to be suitable for size-selective sensing of symmetric anions, whereas shape-selective sensing is achieved via orienting the same strong HB donors to match locations of HB acceptors in the target anion 12,24,[26][27]42 .…”

Fluorescent metallacycle-cored polymers via covalent linkage and their use as contrast agents for cell imaging

“…So far, various SCCs with different geometries, such as 2D metallacycles (25)(26)(27)(28) and 3D metallacages (29)(30)(31)(32), were successfully prepared by the self-assembly of carefully selected metal acceptors and organic donors. Moreover, metal−ligand interactions show good tolerance of other noncovalent interactions such as hydrogen bonding and host−guest interactions, which were used to construct highly advanced functional supramolecular entities, such as mechanically interlocked molecules (33)(34)(35) and supramolecular polymers (36)(37)(38), via orthogonal self-assembly.…”

Adhesion between oppositely charged polyelectrolytes

“…The origin of the adhesion between the polymers is likely to have different mechanisms depending on the materials used, and in many cases more than one might contribute to the adhesion. These mechanisms would include the interdigitation of components so that one layer becomes entangled in the other [10,11,12], hydrogen bonding at the interface between the polymers [13,14,15,16,17], and electrostatic effects [18]. Some conclusions about the mechanisms can be made by comparing A c c e p t e d M a n u s c r i p t 3 the pH dependence of the adhesion between oppositely charged polyelectrolytes with that between two similar polyelectrolytes [19].…”

“…A c c e p t e d M a n u s c r i p t 17 A c c e p t e d M a n u s c r i p t 18 Figure 1. Schematic diagram of the process for a polyacid gel being brought into contact with a polybase grafted polymer layer.…”