Charge-Regulated Spontaneous, Reversible Self-Assembly of the Carboxylic Acid-Functionalized Hydrophilic Fullerene Macroanions in Dilute Solution

Abstract

Fullerene molecule covalently functionalized with 12 carboxylic acid groups on its periphery was synthesized, and its solution behavior was explored. The functionalized fullerene molecules behave as hydrophilic macroions in polar solvents by showing strong attractions with each other mediated from their counterions and consequently self-assembling into single-layer, hollow, spherical blackberry-type structures in solvents with moderate polarity. The fullerene molecules are not touching with each other in the assemblies, and the assembly size can be tuned by changing the polarity of the solvents. More importantly, the transition between the self-assembly and the disassembly of the macroions can be easily achieved by changing temperature. The discovery confirms that the semirigid clusters demonstrate the unique solution behavior of macroions and open up a new way to assemble fullerene into functional materials and devices.

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.…”

Conformational Preferences and the Phase Stability of Fullerene Hexa‐adducts

“…The development of fullerene chemistry facilitates the functionalization of [60‐ I h ]‐fullerene (C 60 ), and made the functionalized C 60 derivatives an important building block of many novel molecular systems . Functional materials like amphiphilic fullerene hexa‐adducts (FHAs),, photoactive FHAs, electroactive FHAs, bioactive FHAs, giant surfactants, and semiconducting giant molecules have been synthesized, and unique supramolecular assembles, including helical supramolecular columns, supramolecular double cables, smectic A phase,, chiral nematic phase,, micelles, and vesicles, were observed among these molecules. The conformation of the C 60 ‐based molecules is essential to its self‐organization behaviors and its material properties because conformational changes can affect the distances among the peripheral functional groups and molecular shapes.…”

Isotope and Hydrogen‐Bond Effects on the Self‐Assembly of Macroions in Dilute Solution

“…[8] Compared to fragile biomolecules, structurally well-defined macroions may be regarded as excellent models. [9] As reportedb efore, macroions with modest charge density,s uch as polyoxometalates (POMs), [10] metal-organic cages( MOCs), [11] uranium clusters, [12] polyhedral oligomeric silsesquioxanes (POSS), [13] dendrimers, [14] and functional C 60 , [15] can self-assemble into single-layer,h ollow,s pherical "blackberry"-type structures through counterion-mediated interaction, [16] accompanied by am odification of their solvation shells. [12a,b, 17] Counterion-mediateda ttraction is considered as the major drivingf orce.…”