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Dumbbell- and bola-shaped amphiphiles are commonly expected to self-assemble into vesicles with condensed hydrophobic domains due to the dominant hydrophobic interaction. In this work, we examined the assemblies of the dumbbell-shaped AC60-AC60 amphiphile, with two carboxylic acid-functionalized fullerenes (AC60) polar head groups linked by an organic tether, and found that they assemble into hollow, spherical blackberry-type structures with porous surfaces, judged by their smaller assemblies in organic solvents with higher polarity and in aqueous solutions with high pH. We attribute the formation of blackberry structures to the organic tether that may be too short to fill up a condensed hydrophobic domain, as confirmed by all-atom simulations. This is further proved by noticing that several bola-type macromolecules with hydrophilic polyethylene glycol (PEG) chain being the linker and no hydrophobic components, AC60-PEG-AC60, can also self-assemble into hollow, spherical assemblies and demonstrate similar pH response as the assemblies from AC60-AC60 dumbbells. Therefore, we conclude that the driving force of the self-assembly for these dumbbell- or bola-shaped molecules is counterion-mediated attraction from the two AC60 head groups rather than the hydrophobic interaction due to the organic linkers. The so-formed blackberry structures here, as well-studied before in other systems, possess porous surfaces, making these charged amphiphiles a valuable model for designing stable nanocontainers with controllable porosity to the change of environment. 

Abstract Macroion‐counterion interaction is essential for regulating the solution behaviors of hydrophilic macroions, as simple models for polyelectrolytes. Here, we explore the interaction between uranyl peroxide molecular cluster Li₆₈K₁₂(OH)₂₀[UO₂(O₂)OH]₆₀(U₆₀) and multivalent counterions. Different from interaction with monovalent counterions that shows a simple one‐step process, isothermal titration calorimetry, combined with light/X‐ray scattering measurements and electron microscopy, confirm a two‐step process for their interaction with multivalent counterions: an ion‐pairing betweenU₆₀and the counterion with partial breakage of hydration shells followed by strongU₆₀‐U₆₀attraction, leading to the formation of large nanosheets with severe breakage and reconstruction of hydration shells. The detailed studies on macroion‐counterion interaction can be nicely correlated to the microscopic (self‐assembly) and macroscopic (gelation or phase separation) phase transitions in the diluteU₆₀aqueous solutions induced by multivalent counterions. 

Abstract The distinct molecular states — single molecule, assembly, and aggregate — of two ionic macromolecules, TPPE‐APOSS and TPE‐APOSS, are easily distinguishable through their tunable fluorescence emission wavelengths, which reflect variations in intermolecular distances. Both ionic macromolecules contain aggregation‐induced emission (AIE) active moieties whose emission wavelengths are directly correlated to their mutual distances in solution: far away from each other as individual molecules, maintaining a tunable and relatively long distance in electrostatic interactions‐controlled blackberry‐type assemblies (microphase separation), or approaching van der Waals close distance in aggregates (macrophase separation). Furthermore, within the blackberry assemblies, the emission wavelength decreases monotonically with increasing assembly size, indicative of shorter intermolecular distances at nanoscale. The emission changes of TPPE‐APOSS blackberry assemblies can even be visually distinguishable by eyes when their sizes and intermolecular distances are tuned. Molecular dynamics simulations further revealed that macromolecules are confined in various conformations by controllable intermolecular distances within the blackberry structure, thereby resulting in fluorescence emission with tunable wavelength. 

Abstract The critical gelation conditions observed in dilute aqueous solutions of multiple nanoscale uranyl peroxide molecular clusters are reported, in the presence of multivalent cations. This gelation is dominantly driven by counterion‐mediated attraction. The gelation areas in the corresponding phase diagrams all appear in similar locations, with a characteristic triangle shape outlining three critical boundary conditions, corresponding to the critical cluster concentration, cation/cluster ratio, and the degree of counterion association with increasing cluster concentration. These interesting phrasal observations reveal general conditions for gelation driven by electrostatic interactions in hydrophilic macroionic solutions.