Monitoring the Discontinuous Dodecamer–Icosamer Transition of a Calix[4]arene‐Derived Surfactant by Time‐Resolved Small‐Angle X‐ray Scattering

Takahashi, Rintaro; Matsumoto, Sakiko; Fujii, Shota; Narayanan, Theyencheri; Sakurai, Kazuo

doi:10.1002/anie.201702260

Cited by 9 publications

(7 citation statements)

References 35 publications

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“…Fujii and colleagues proposed the concept of Platonic micelles in 2017, stating that, in the case of spherical micelles, when N agg becomes small enough (e.g., <30), certain numbers of N agg tend to appear more preferably than others; these numbers are 4, 6, 8, 12, 20, and 24. ,, Such a preference is explained by the Tammes problem of how to obtain the best coverage [ D ( N )] of a spherical surface with multiple identical caps ( N ). In this case, higher coverage is considered to give lower free energy in terms of surface tension. , Interestingly, most of the numbers coincide with the surface or vertex numbers of a Platonic solid that is a regular, convex polyhedron constructed by congruent, regular, polygonal faces with the same number of faces.…”

Section: Results and Discussionmentioning

confidence: 99%

Structural Polymorphism of Resorcinarene Assemblies

et al. 2020

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In 1997, a study based on X-ray crystallography revealed that resorcinarenes adopt a hexameric capsule-like structure. The function of resorcinarenes has been discussed on the basis of this structure; however, our recent study showed that the hexamer may be only one of resorcinarenes' polymorphic members. Here, we present the solvent dependence of the aggregation number of C-undecylresorcinarene in watersaturated toluene and chloroform using small-angle neutron and X-ray scattering and analytical ultracentrifugation measurements. We found that a new octamer was formed in toluene where the eight resorcinarene units were placed at the vertices of a regular cube; this contrasts to the previous structure in chloroform, namely, a hexamer with the six resorcinarenes located at the vertices of a regular octahedron that has a cavity inside where chloroform molecules are pooled.

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Section: Results and Discussionmentioning

confidence: 99%

Structural Polymorphism of Resorcinarene Assemblies

et al. 2020

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“…Interestingly, the value of N agg always matches the vertex number of regular polyhedra, that is, Platonic solids. We named such micelles Platonic micelles and have already identified many calix[4]arene-based monodisperse micelles. − …”

Section: Introductionmentioning

confidence: 99%

Rediscovering the Monodispersity of Sulfonatocalix[4]arene-Based Micelles

et al. 2018

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When the micellar aggregation number ( N) is small enough (<30), the N matches the value of vertexes of a regular polyhedron: Platonic solids, and demonstrates perfect monodispersity. These micelles are named Platonic micelles and are particularly found in the system of calix[4]arene-based micelles due to the rigid structure of the backbone molecule. Although sulfonatocalix[4]arene-based micelles are among the most studied host molecules in supramolecular chemistry, their micellar properties as Platonic micelles have thus far been overlooked. In this study, we prepared various sulfonatocalix[4]arene-based amphiphiles bearing alkyl chains with different lengths and investigated their aggregation behavior. When the amphiphiles formed spherical micelles, they demonstrated monodispersity in terms of N, whose value changed from 4 to 17, and then to 24, upon increasing the carbon number in each alkyl chain from C5 to C6, and then to C7, respectively. Although the numbers 17 and 24 do not match the vertices of regular polyhedra, these values can be reasonably explained by the Thomson problem, which considers the Coulomb potential for calculating the best packing on a sphere with multiple identical spherical caps. This study describes rediscovery of the monodispersity of sulfonatocalix[4]arene-based micelles, which is consistent with the idea of Platonic micelles.

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“…In another investigation, the transition from spherical to cylindrical micelles upon mixing nonionic and anionic micelles revealed a two-step process involving unimer exchange between micelles followed by fusion of mixed spherical micelles to form cylindrical micelles [65]. In the case of a so-called platonic micellar system, a sharp transition from dodecamer to icosamer morphology was detected with the change in ionic strength [66]. Resolving this type of shape transformations require very precise measurements with SAXS intensities comparable on an absolute scale.…”

Section: Probing the Pathways Of Self-assemblymentioning

confidence: 95%

Synchrotron Scattering Methods for Nanomaterials and Soft Matter Research

Narayanan

Konovalov

2020

Materials

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This article aims to provide an overview of broad range of applications of synchrotron scattering methods in the investigation of nanoscale materials. These scattering techniques allow the elucidation of the structure and dynamics of nanomaterials from sub-nm to micron size scales and down to sub-millisecond time ranges both in bulk and at interfaces. A major advantage of scattering methods is that they provide the ensemble averaged information under in situ and operando conditions. As a result, they are complementary to various imaging techniques which reveal more local information. Scattering methods are particularly suitable for probing buried structures that are difficult to image. Although, many qualitative features can be directly extracted from scattering data, derivation of detailed structural and dynamical information requires quantitative modeling. The fourth-generation synchrotron sources open new possibilities for investigating these complex systems by exploiting the enhanced brightness and coherence properties of X-rays.

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Monitoring the Discontinuous Dodecamer–Icosamer Transition of a Calix[4]arene‐Derived Surfactant by Time‐Resolved Small‐Angle X‐ray Scattering

Cited by 9 publications

References 35 publications

Structural Polymorphism of Resorcinarene Assemblies

Structural Polymorphism of Resorcinarene Assemblies

Rediscovering the Monodispersity of Sulfonatocalix[4]arene-Based Micelles

Synchrotron Scattering Methods for Nanomaterials and Soft Matter Research

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