Tectonic arrangement of BaCO3 nanocrystals into helices induced by a racemic block copolymer (original) (raw)
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Biomimetic Hierarchical Assembly of Helical Supraparticles from Chiral Nanoparticles
ACS nano, 2016
Chiroptical materials found in butterflies, beetles, stomatopod crustaceans, and other creatures are attributed to biocomposites with helical motifs and multiscale hierarchical organization. These structurally sophisticated materials self-assemble from primitive nanoscale building blocks, a process that is simpler and more energy efficient than many top-down methods currently used to produce similarly sized three-dimensional materials. Here, we report that molecular-scale chirality of a CdTe nanoparticle surface can be translated to nanoscale helical assemblies, leading to chiroptical activity in the visible electromagnetic range. Chiral CdTe nanoparticles coated with cysteine self-organize around Te cores to produce helical supraparticles. d-/l-Form of the amino acid determines the dominant left/right helicity of the supraparticles. Coarse-grained molecular dynamics simulations with a helical pair-potential confirm the assembly mechanism and the origin of its enantioselectivity, pr...
Trends in design of C 2 -symmetric supramolecular chiral gelators
In recent years, C 2-symmetric supramolecular chiral gelators have emerged as a powerful tool for the construction of functional nanostructures to be applied in different fields. Myriad applications of these nanoscale architectures, in fields such as cell culture, dye adhesion and release, bacterial adhesion, tissue engineering, drug delivery, and chiroptical switches are being envisaged. This review attempts to present a succinct overview of the current state of research on functional nano-scale systems, the design, synthesis, and applications of self-assembled C 2-symmetric supramolecular chiral gelators "engineered" to carry out precise functions, with an emphasis on the design on the basis of different cores for supramolecular self-assembly. This highlight gives a brief flavor of the development of C 2-symmetric supramolecular chiral gelators broadly from the first decade of the 2000 s up to now. A particular theme is the emergence of C 2-symmetric supramolecular chiral gels and increasing hi-tech niche application areas with respect to design and synthesis. Control and exploitation of design of C 2-symmetric supramolecular chiral gels form a huge part of the grand challenge of directed assembly of extended structures with targeted properties and applications.
Formation of Chiral Solids via a Molecular Building Block Approach
Journal of Solid State Chemistry, 2000
The application of principals of molecular recognition to the design of organic and inorganic solids is leading to remarkable progress in the preparation of porous and chiral materials. A new area of supramolecular complexes is metallamacrocycles, large molecules that are sewn together using metal linkages. Metallacrowns are a member of this class of inorganic complexes. In this article we develop a strategy for the preparation of solids that are chiral using metallacrowns as the centerpiece. First, we introduce the available structure types for these molecules and then proceed to describe some of the physical properties associated with this unique molecular assembly. We demonstrate that chirality can be incorporated simply and inexpensively into these molecules and then we show how the metallacrowns can be used as building blocks to make layered solids with chiral channels. Finally, we assess more general strategies that could be used to engineer truly porous and chiral materials with high metal densities.
Construction of Chiral, Helical Nanoparticle Superstructures: Progress and Prospects
Advanced Materials, 2019
Chiral nanoparticle (NP) superstructures, in which discrete NPs are assembled into chiral architectures, represent an exciting and growing class of nanomaterials. Their enantiospecific properties make them promising candidates for a variety of potential applications. Helical NP superstructures are a rapidly expanding subclass of chiral nanomaterials in which NPs are arranged in three dimensions about a screw axis. Their intrinsic asymmetry gives rise to a variety of interesting properties, including plasmonic chiroptical activity in the visible spectrum, and they hold immense promise as chiroptical sensors and as components of optical metamaterials. Herein, a concise history of the foundational conceptual advances that helped define the field of chiral nanomaterials is provided, and some of the major achievements in the development of helical nanomaterials are highlighted. Next, the key methodologies employed to construct these materials are discussed, and specific merits that are o...
Angewandte Chemie International Edition, 2020
The single gyroid phase as well as the alternating double network gyroid, composed of two alternating single gyroid networks, hold a significant place in ordered nanoscale morphologies for their potential applications as photonic crystals, metamaterials and templates for porous ceramics and metals. Here, we report the first alternating network cubic liquid crystals. They form through self-assembly of X-shaped polyphiles, where glycerol-capped terphenyl rods lie on the gyroid surface while semiperfluorinated and aliphatic sidechains fill their respective separate channel networks. This new self-assembly mode can be considered as a two-color symmetry-broken double gyroid morphology, providing a tailored way to fabricate novel chiral structures with sub-10 nm periodicities using achiral compounds. New routes to chirality from initially achiral systems are of particular contemporary interest for obtaining chiral templates in asymmetric synthesis and catalysis. [1] This is important for the use in different fields of material-and nanoscience [2] as well as for the understanding of fundamental principles of the emergence of biological homochirality. [3] Creating chirality in liquids and liquid crystals (LCs), having
Addition: Nanoparticle-Directed Crystallization of Calcium Carbonate
Advanced Materials, 2002
Natural organisms that produce biological composites exert exquisite control over the minerals they deposit, creating materials of myriad shapes and sizes that are often of high strength. Mineralized tissues are often found to contain polymorphs and individual minerals whose crystal morphology, size, and orientation are determined by local conditions and, in particular, the presence of matrix proteins or other macromolecules. The processes and materials that control such crystal nucleation and growth are of great interest to materials scientists who seek to manufacture composite materials and crystalline forms analogous to those produced by nature. [2±5] There are several approaches to exploring the promoting effect of templates on crystal nucleation and growth. The first approach focuses on the functions of the biological matrix. Since most biomineral formation processes are controlled by acidic matrix proteins or glycoproteins, numerous efforts to mimic the action of matrix proteins have focused on using synthetic polymeric analogues as substrates for the deposition of polycrystalline inorganic materials. For instance, calcium carbonate has been deposited on model polymeric substrates [6] and even inorganic polymer surfaces; [7] iron oxides and tin oxides have been deposited on sulfonated polystyrene films; [8] cadmium sulfide and titanium oxide have been assembled on absorbed polyelectrolyte surfaces; [9] and hydroxyapatite has been deposited on polymers. [10] The second approach has made use of the well-ordered two-dimensional structure of a self-assembled film on a solid substrate or a Langmuir film at the air±water interface as the nucleating template. Calcium carbonate, [11] iron oxides, [12] cadmium or zinc sulfide, [9] hydroxyapatite, [13] and more recently zirconium oxides have been grown under such amphiphilic monolayers. [14] A recent approach has employed synthetic supramolecular assemblies to offer semi-rigid templates for calcium carbonate crystallization. For example, Groves and co-workers have demonstrated that the functions of the acidic glycoprotein matrix could be mimicked in vitro with a supramolecular assembly of porphyrin amphiphiles. [15] The ability to construct organized nanoscale, microscopic, and bulk inorganic materials from molecular components is important in electronics, catalysis, magnetism, sensory devices, and mechanical design. [3] Such complex, three-dimensional structures, if produced synthetically, could find important applications as lightweight ceramics, catalyst supports, biomedical implants, and robust membranes for high-temperature separation technology. [16] In this communication, we report a novel synthetic approach to the fabrication of composite materials via controlling crystal growth with monolayer-protected gold nanoparticles as a template. The mineral chosen for this study was calcium carbonate (CaCO 3 ), one of the most abundant biominerals, [17] and one that can be grown easily under laboratory conditions. We show that spheroids are formed by nucleation of CaCO 3 at the surface of the acid-terminated gold nanoparticles. The resulting crystalline calcium carbonate polymorph is vaterite. We can also prepare unusual CaCO 3 needles by using the cooperative effect between Mg 2+ and the nanoparticles.