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Self-assembly of amphiphilic molecules is an important phenomenon attracting a broad range of research. In this work, we study the self-assembly of KTOF4 sphere–rod amphiphilic molecules in mixed water–dioxane solvents. The molecules are of a T-shaped geometry, comprised of a hydrophilic spherical Keggin-type cluster attached by a flexible bridge to the center of a hydrophobic rod-like oligodialkylfluorene (OF), which consists of four OF units. Transmission electron microscopy (TEM) uncovers self-assembled spherical structures of KTOF4 in dilute solutions. These spheres are filled with smectic-like layers of KTOF4 separated by layers of the solution. There are two types of layer packings: (i) concentric spheres and (ii) flat layers. The concentric spheres form when the dioxane volume fraction in the solution is 35–50 vol%. The flat layers are formed when the dioxane volume fraction is either below (20 and 30 vol%.) or above (55 and 60 vol%.) the indicated range. The layered structures show no in-plane orientational order and thus resemble thermotropic smectic A liquid crystals and their lyotropic analogs. The layered packings reveal edge and screw dislocations. Evaporation of the solvent produces a bulk birefringent liquid crystal phase with textures resembling the ones of uniaxial nematic liquid crystals. These findings demonstrate that sphere–rod molecules produce a variety of self-assembled structures that are controlled by the solvent properties. 

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 strong U60‐U60 attraction, 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 dilute U60 aqueous solutions induced by multivalent counterions. 

Initiating depolymerization at ambient temperature by nonthermal air plasma provides a novel and promising route to convert polymer wastes to valuable small molecules. This study showed that the selectivity of partial oxidation of polyvinyl alcohol (PVA) initiated by nonthermal air plasma can be controlled by the polymer to TiO2 ratio and AC (alternative current) voltage and frequency. Transient responses to applying AC (alternating current) power showed that the CO2 led to the formation of CO, propionaldehyde, and acetaldehyde. Significant formation of propionaldehyde showed that -C-OH in PVA can be directly converted to CH3 in propionaldehyde, unraveling a new reaction pathway in nonthermal plasma chemistry. The selectivity of aldehydes is at the same level as that of CO2. The selectivity of aldehydes was further enhanced by nitrogen plasma while the selectivity toward CO2 was increased in the presence of TiO2. This study demonstrated that ambient nonthermal air plasma could provide a potentially effective approach for the selective conversion of polymers to desired small molecules. 

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. 

Macroionic solutions behave quite differently from small ions in solution or colloids in suspension, representing a previously missing and very important transitional stage, and can further be connected to solutions of polyelectrolytes, including proteins and DNA ( e.g. , similarities between “blackberry” formation and virus capsid formation). While synthesis and characterization have produced an immense database regarding the self-assembly behavior of macroions in solution resulting in many empirical rules and guidelines, theory and simulations are sorely needed to connect these disparate threads into a cohesive and coherent narrative of macroionic solution theory and to provide guidance for future work. We recently developed a versatile coarse-grained model specifically designed for modelling the self-assembly of macroions in solution and have answered some of the most outstanding questions about the solution behavior of macroions including the source of the attractive force between like-charged macroions and how they self-assemble into a 2D monolayer structure. 

Abstract Inorganic salts usually demonstrate simple phasal behaviors in dilute aqueous solution mainly involving soluble (homogeneous) and insoluble (macrophase separation) scenarios. Herein, we report the discovery of complex phase behavior involving multiple phase transitions of clear solution – macrophase separation – gelation – solution – macrophase separation in the dilute aqueous solutions of a structurally well-defined molecular cluster [Mo₇O₂₄]⁶⁻macroanions with the continuous addition of Fe³⁺. No chemical reaction was involved. The transitions are closely related to the strong electrostatic interaction between [Mo₇O₂₄]⁶⁻and their Fe³⁺counterions, the counterion-mediated attraction and the consequent charge inversion, leading to the formation of linear/branched supramolecular structures, as confirmed by experimental results and molecular dynamics simulations. The rich phase behavior demonstrated by the inorganic cluster [Mo₇O₂₄]⁶⁻expands our understanding of nanoscale ions in solution.