Inducing Hetero‐aggregation of Different Azo Dyes through Electrostatic Self‐Assembly

Mariani, Giacomo; Kutz, Anne; Di, Zhenyu; Schweins, Ralf; Gröhn, Franziska

doi:10.1002/chem.201605194

Cited by 9 publications

(12 citation statements)

References 51 publications

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“…When formation of nanoparticles is observed with pure organic compounds or binary mixtures in solution, three types of behavior are observed: Indefinite growth, where addition of monomer to ribbon or cylinder structures continues until the monomer is exhausted, giving length scales of micrometers or more Limited growth, where addition of monomer to particles or assembly of multimers to form aggregates gives a distribution of sizes up to some limit. − Methods such as small-angle X-ray and neutron scattering indicate the mean length scale of the aggregates, but as in the case of asphaltenes, the actual distribution is difficult to measure for soft nanoaggregates such as polymers. Sphere formation, where the geometry of the monomers and their assembly gives a stable micelle or hollow sphere of fixed dimension. , …”

Section: Molecular Basis For Distributed Nanoaggregate Propertiesmentioning

confidence: 99%

“…Limited growth, where addition of monomer to particles or assembly of multimers to form aggregates gives a distribution of sizes up to some limit. − Methods such as small-angle X-ray and neutron scattering indicate the mean length scale of the aggregates, but as in the case of asphaltenes, the actual distribution is difficult to measure for soft nanoaggregates such as polymers.…”

Section: Molecular Basis For Distributed Nanoaggregate Propertiesmentioning

confidence: 99%

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Distributed Properties of Asphaltene Nanoaggregates in Crude Oils: A Review

et al. 2021

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The molecules in petroleum asphaltenes follow a molecular structure continuum similar to the rest of the oil but differ in the formation of nanoaggregates in solution. The nature of the aggregation, its size distribution, and dimensions of the nanoaggregates is still debated, and the impact of this aggregation on phase behavior, physical properties, and the processing of heavy petroleum fractions remains unclear. This review first discusses the role of nanoaggregates in the phase separation of asphaltenes, then examines the literature on subfractionation of the asphaltene fraction to define how different molecules partition. Efforts to measure the distribution of nanoaggregate size are summarized, and the roles of size distribution in the behavior of asphaltenes during sedimentation, emulsion formation, and refinery processing are examined. Finally, the molecular basis for formation of a distribution of aggregate sizes/properties is considered. The molecular weight ranges as high as 40,000 Da but the size is below 100 nm. Although few direct experimental data are available for the distribution of aggregate properties, three behaviors indicate the importance of portions of the nanoaggregate population. The highest molecular weight aggregates are the least soluble, driving phase behavior when the asphaltenes are partially precipitated. A portion of these large aggregates are also most responsible for the stabilization of asphaltene films at oil–water interfaces, which stabilize oil-in-water emulsions. The vanadium and nickel species that are most resistant to removal during refining of vacuum residues are also found in the most aggregated fraction, although the stability of the aggregates at process temperatures is not yet proven. Average properties for the asphaltene fraction, including both free molecules and nanoaggregates, are sufficient for prediction of onset of asphaltene phase separation, gravity segregation, and properties such as density and viscosity.

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Section: Molecular Basis For Distributed Nanoaggregate Propertiesmentioning

confidence: 99%

Section: Molecular Basis For Distributed Nanoaggregate Propertiesmentioning

confidence: 99%

Distributed Properties of Asphaltene Nanoaggregates in Crude Oils: A Review

et al. 2021

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“…The Gröhn group introduced a novel concept for forming electrostatically self-assembled nano-objects in solution by using “structural counterions” and presented a variety of supramolecular structures in solution formed by electrostatic self-assembly ( Gröhn, 2008 ; Li et al, 2009 ; Ruthard et al, 2009 ; Willerich et al, 2009 ; Gröhn, 2010 ; Gröhn et al, 2010 ; Kutz et al, 2016 ; Mariani et al, 2017a ; Frühbeißer and Gröhn, 2017 ; Frühbeißer et al, 2018 ). Similar to the material and the multilayer case, structures from various building block combinations can be created.…”

Section: Nano-objects By Electrostatic Self-assembly In Solutionmentioning

confidence: 99%

“…PAMAM dendrimers with the trivalent dye Ar27 form pH-switchable capsules (see section Switchable Structures) ( Gröhn et al, 2010 ). Even ternary systems with two different dyes are possible enabling hetero π-π stacks as directional secondary forces ( Mariani et al, 2017a ). Thus, it is not only possible to form finite-size assemblies; a large range of structures is also accessible even within this model system.…”

Section: Structural Variety Of Supramolecular Assemblies In Solutionmentioning

confidence: 99%

Functional Nano-Objects by Electrostatic Self-Assembly: Structure, Switching, and Photocatalysis

2022

Self Cite

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The design of functional nano-objects by electrostatic self-assembly in solution signifies an emerging field with great potential. More specifically, the targeted combination of electrostatic interaction with other effects and interactions, such as the positioning of charges on stiff building blocks, the use of additional amphiphilic, π−π stacking building blocks, or polyelectrolytes with certain architectures, have recently promulgated electrostatic self-assembly to a principle for versatile defined structure formation. A large variety of architectures from spheres over rods and hollow spheres to networks in the size range of a few tenths to a few hundred nanometers can be formed. This review discusses the state-of-the-art of different approaches of nano-object formation by electrostatic self-assembly against the backdrop of corresponding solid materials and assemblies formed by other non-covalent interactions. In this regard, particularly promising is the facile formation of triggerable structures, i.e. size and shape switching through light, as well as the use of electrostatically assembled nano-objects for improved photocatalysis and the possible solar energy conversion in the future. Lately, this new field is eliciting an increasing amount of understanding; insights and limitations thereof are addressed in this article. Special emphasis is placed on the interconnection of molecular building block structures and the resulting nanoscale architecture via the key of thermodynamics.

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“…More recently, the Gröhn group developed a novel class of dendrimer assemblies based on a so-called “structural unit”: a multivalent organic and anionic building block of a particular geometry. , In contrast with the compounds used by others, this structural unit provides not only the opposite charges but also a second driving force, for example, π–π stacking, arising from their aromatic structures. This approach has allowed us to achieve some control over the particle shape and functionality of dendrimer-containing structures; for example, different anionic organic dye molecules assemble with cationic PAMAM dendrimers into a variety of supramolecular aggregates, including spheres, rods, ellipsoids, vesicles, and core–shell nanoparticles. − Moreover, azo-based dye molecules allow us to prepare structures that respond to external triggers such as light, pH, and additives like cyclodextrin. − …”

Section: Introductionmentioning

confidence: 99%

Hierarchical Assemblies of Dendrimers Embedded in Networks of Lanthanide-Based Supramolecular Polyelectrolytes

et al. 2019

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Supramolecular assemblies of dendrimers, with defined structures and tunable functionalities, are promising functional materials. Here we report a ternary system (lanthanide ion/bis-ligand/PAMAM dendrimer) capable of assembling in a cooperative way by forming a complex between anionic (metal–ligand) coordination polymers and the cationic PAMAM dendrimers. In off-stoichiometric mixtures, charge-stabilized spherical nanoparticles of ∼100 nm appear; they have either negative or positive surface charges depending on what the excess component is. Introducing different trivalent lanthanide ions, Ln(III), in the coordination allows tuning both the luminescence emission spectrum and the magnetic relaxivity without affecting the assembly process or the final structure of the particles; this makes them interesting in the context of application. Moreover, the incorporated dendrimer allows us to add functional nanocargo, for example, Au nanoparticles in the cavities of these molecules, again without disturbing the assembly. In this novel way, we obtain versatile, multilevel hierarchical supramolecular dendrimer-containing assemblies with good control over their structures and functionalities. This is very difficult to achieve with conventional covalent compounds but becomes possible because of the supramolecular nature of the coordination polymers and the strong cooperative assembly.

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Inducing Hetero‐aggregation of Different Azo Dyes through Electrostatic Self‐Assembly

Cited by 9 publications

References 51 publications

Distributed Properties of Asphaltene Nanoaggregates in Crude Oils: A Review

Distributed Properties of Asphaltene Nanoaggregates in Crude Oils: A Review

Functional Nano-Objects by Electrostatic Self-Assembly: Structure, Switching, and Photocatalysis

Hierarchical Assemblies of Dendrimers Embedded in Networks of Lanthanide-Based Supramolecular Polyelectrolytes

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