Self‐Assembly of Subnanometer‐Scaled Polyhedral Oligomeric Silsesquioxane (POSS) Macroions in Dilute Solution

Abstract

Both positively and negatively charged polyhedral oligomeric silsesquioxane (POSS) electrolytes were observed to self-assemble into blackberry-type supramolecular structures in water/acetone mixed solvents, driven by the counterion-mediated attraction. Laser light-scattering studies reveal that the sizes of the blackberry structures increase with increasing acetone content, which suggests a charge-regulated process. Studies on two oppositely charged POSS macroions with identical charges and similar sizes show the discrepancy

Supramolecular Assembly of Poly(propyleneimine) Dendrimers Driven By Simple Monovalent Counterions

“…POM cluster Mo 72 Fe 30 (R g = 1.3 nm;e ffective charge( Z) = À7) (Figure 1b), which contains many metal atoms in its structure, was also compared to these two systems. As reported earlier, [61,62] z POSS = À59.7 and u POSS = À12.7kT,a nd z POM = À56 and u POM = À6.8kT.F inding the u value for each clusteront he y axis of the plot shown in Figure 10 bb ased on their measured z values showedp redicted values u POSS = À10.3kT and u POM = À8.1kT,w hich are very close to the reported values. These results showt hat there is ac orrelation between the solutionb ehavior of inorganic clusters and organic polyelectrolytes.B ecause polyelectrolytesa re the most-challenging group of polymers in solution, finding ac orrelation between well-studied inorganic clusters andp olyelectrolytew ith poorly understood solutionb ehavior could be ap erfect way to increaseu nderstanding of this important family of polymers in solution.…”

Spontaneous Self‐Assembly of γ‐Cyclodextrins in Dilute Solutions with Tunable Sizes and Thermodynamic Stability

“…Comparing γ‐CD‐P with macroions such as {Mo 132 } and ionic POSS, they can all self‐assemble in mixed solvents, but only γ‐CD‐P can form blackberries with either an increasing or decreasing size trend as the amount of acetone is increased 8f. 12 The difference may be related to the charge density of macroions among which γ‐CD‐P has the lowest charge density (1.050 per nm 2 ).…”

Tuning of Polyoxopalladate Macroanionic Hydration Shell via Countercation Interaction

“…Tremendous efforts have been made to understand the ion-pairs and hydrations hells in solution, [2] especially in biological systems, [3] because they are critical for ion transport, biochemical hydrolysis and protein stability.H owever,u nderstanding these biomacromolecules in vitro is difficult, because they are fragile and unstable once extracted from the biological environment. [4] Studying structurally well-defined, simple macromolecules with identical size and tunable charge density would be an alternative way.P olyoxometalates [5] (POMs) are discrete, anionic polyatomic ions with sizes in the nanometer regime and excellent modelsw ith similars olution behavior as biomacromolecules in the wayt hey interact with small countercations in solution.P OMs, alongw ith many othert ypes of macroions, such as metal-organic nanocages, [6] polyhedralo ligomeric silsesquioxane( POSS), [7] functionalized C 60 [8] and dendrimers, [9] can self-assemble into single-layered, hollow,s pherical "blackberry"-type structures by counterion-mediated attraction, [10] with a mechanism similar to virus capsid formation, demonstrating impressive self-recognition capabilityd ue to delicate longrange electrostatic interaction, [11] etc. Such hydrophilic macroions possess well-definedh ydration shells,w hich couldb e studiedt or evealt he interaction between hydration shells and counterions and the type of ion-pairs.…”