Unbalanced 2D Chiral Crystallization of Pentahelicene Propellers and Their Planarization into Nanographenes.
Ontology highlight
ABSTRACT:
SUBMITTER: Voigt J
PROVIDER: S-EPMC8362048 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:Chiral molecular propeller conformations have been induced to various triaryl structures including trityl derivatives and triaryl boranes. For borane-amine adducts, such induced propeller chirality has not been reported yet due to the low energy barrier for racemization in common triarylboranes such as B(C6 H5 )3 or B(C6 F5 )3 . Herein, we demonstrate that point chirality in side chains of chiral triarylborane-ammonia adducts, which feature intramolecular hydrogen bonds in addition to the dative N→B bond, can efficiently be transferred to triarylborane propeller chirality. Employing X-ray crystallography and ECD/VCD spectroscopy for structural characterizations, we investigate three examples with different steric demands of the incorporated chiral alkoxy side groups. We elucidate the conformational preferences of the molecular propellers. Furthermore, we show that computationally predicted conformational preferences obtained for the isolated, only implicitly solvated molecules are actually opposite to the experimentally observed ones.
| S-EPMC7898383 | biostudies-literature
Project description:Nanographenes are emerging as a distinctive class of functional materials for electronic and optical devices. It is of remarkable significance to enrich the precise synthetic chemistry for these molecules. Herein, we develop a facile strategy to recompose helicenes into chiral nanographenes through a unique oxidative cyclo-rearrangement reaction. Helicenes with 7~9 ortho-fused aromatic rings are firstly oxidized and cyclized, and subsequently rearranged into nanographenes with an unsymmetrical helicoid shape through sequential 1,2-migrations. Such skeletal reconstruction is virtually driven by the gradual release of the strain of the highly distorted helicene skeleton. Importantly, the chirality of the helicene precursor can be integrally inherited by the resulting nanographene. Thus, a series of chiral nanographenes are prepared from a variety of carbohelicenes and heterohelicenes. Moreover, such cyclo-rearrangement reaction can be sequentially or simultaneously associated with conventional oxidative cyclization reactions to ulteriorly enrich the geometry diversity of nanographenes, aiming at innovative properties.
| S-EPMC8119938 | biostudies-literature
Project description:We designed a straightforward synthetic route towards a full-fledged family of π-extended helicenes: superhelicenes. They have two hexa-peri-hexabenzocoronenes (HBCs) in common that are connected via a central five-membered ring. By means of structurally altering this 5-membered ring, we realized a versatile library of molecular building blocks. Not only the superhelicene structure, but also their features are tuned with ease. In-depth physico-chemical characterizations served as a proof of concept thereof. The superhelicene enantiomers were separated, their circular dichroism was measured in preliminary studies and concluded with an enantiomeric assignment. Our work was rounded-off by crystal structure analyses. Mixed stacks of M- and P-isomers led to twisted molecular wires. Using such stacks, charge-carrier mobilities were calculated, giving reason to expect outstanding hole transporting properties.
| S-EPMC8456895 | biostudies-literature
Project description:Carbon nanotubes (NTs) are graphene sheets rolled into a 1D material, with a specific chirality that defines its structure and properties. Graphene has triggered the development of thousands of 2D materials, which in principle could also be rolled into 1D NTs. However, most of these NTs have not been proposed due to difficulties in the generation of atomic coordinates for chiral NTs from 2D materials with a non-hexagonal lattice or multi-layered materials. In this paper we present Chiraltube, an open-source Python code that allows the quick generation of a complete NT with any chirality from the unit cell of its original 2D material. We explain the inner workings of the code as well as the theoretical background on which it is built, generalizing concepts from the construction of chiral and achiral carbon NTs to work on any other 2D material. We show various examples of the resulting chiral NT structures built from phosphorene, MoS2 and Ti3C2, and present some analysis on the interatomic distortion in the outermost layers of these NTs, as well as the results of ab initio electronic structure calculations on a set of phosphorene NTs generated by the program, showing the immediate practicality and usefulness of the program. We also explore some limitations and details of the tool as well as further work to be done.
| S-EPMC10729892 | biostudies-literature
Project description:The compound, {6,6'-dimeth-oxy-2,2'-[(4-azaheptane-1,7-di-yl)bis-(nitrilo-meth-an-yl-idyne)]diphenolato}zinc(II) methanol monosolvate, [Zn(C22H27N3O4)]·CH3OH, at 298 K crystallizes in the ortho-rhom-bic space group Pna21. The Zn atom is coordinated by a penta-dentate Schiff base ligand in a distorted trigonal-bipyramidal N3O2 geometry. The equatorial plane is formed by the two phenolic O and one amine N atom. The axial positions are occupied by two amine N atoms. The distorted bipyramidal geometry is also supported by the trigonality index (τ), which is found to be 0.85 for the mol-ecule. In the crystal, methanol solvent mol-ecule is connected to the complex mol-ecule by an O-H⋯O hydrogen bond and the complex mol-ecules are connected by weak supra-molecular inter-actions, so achiral mol-ecules generate a chiral crystal. The Hirshfeld surface analysis suggests that H⋯H contacts account for the largest percentage of all inter-actions.
| S-EPMC8100267 | biostudies-literature
Project description:A mean-field theoretical approach is applied to streptavidin tetramerization and two-dimensional (2D) crystallization. This theory includes, in particular, solvent-residue interactions following the inhomogeneous Flory-Huggins model for polymers. It also takes into account residue-residue interactions by using tabulated pair interaction parameters. This theory allows one to explicitly calculate the entropy of the inhomogeneous system. We show that hydrophobic interactions are responsible for the stability of tetramerization. Within the present theory, the equilibrium distance between the two dimers is the same as that determined experimentally. The free energy of tetramerization (i.e., dissociation of the two dimers) is 50 k(B)T. Unlike tetramerization, hydrophobic interactions alone are not sufficient to stabilize the 2D crystal C(222), but solvent-mediated residue-residue interactions give the most important contribution.
| S-EPMC1301389 | biostudies-other
Project description:Buckling and wrinkling instabilities are failure modes of elastic sheets that are avoided in the traditional material design. Recently, a new paradigm has appeared where these instabilities are instead being utilized for high-performance applications. Multiple approaches such as heterogeneous gelation, capillary stresses, and confinement have been used to shape thin macroscopic elastic sheets. However, it remains a challenge to shape two-dimensional self-assembled monolayers at colloidal or molecular length scales. Here, we show the existence of a curvature instability that arises during the crystallization of finite-sized monolayer membranes of chiral colloidal rods. While the bulk of the membrane crystallizes, its edge remains fluid like and exhibits chiral ordering. The resulting internal stresses cause the flat membrane to buckle macroscopically and wrinkle locally. Our results demonstrate an alternate pathway based on intrinsic stresses instead of the usual external ones to assemble non-Euclidean sheets at the colloidal length scale.
| S-EPMC5658384 | biostudies-literature
Project description:Electron crystallography relies on electron cryomicroscopy of two-dimensional (2D) crystals and is particularly well suited for studying the structure of membrane proteins in their native lipid bilayer environment. To obtain 2D crystals from purified membrane proteins, the detergent in a protein-lipid-detergent ternary mixture must be removed, generally by dialysis, under conditions favoring reconstitution into proteoliposomes and formation of well-ordered lattices. To identify these conditions a wide range of parameters such as pH, lipid composition, lipid-to-protein ratio, ionic strength and ligands must be screened in a procedure involving four steps: crystallization, specimen preparation for electron microscopy, image acquisition, and evaluation. Traditionally, these steps have been carried out manually and, as a result, the scope of 2D crystallization trials has been limited. We have therefore developed an automated pipeline to screen the formation of 2D crystals. We employed a 96-well dialysis block for reconstitution of the target protein over a wide range of conditions designed to promote crystallization. A 96-position magnetic platform and a liquid handling robot were used to prepare negatively stained specimens in parallel. Robotic grid insertion into the electron microscope and computerized image acquisition ensures rapid evaluation of the crystallization screen. To date, 38 2D crystallization screens have been conducted for 15 different membrane proteins, totaling over 3000 individual crystallization experiments. Three of these proteins have yielded diffracting 2D crystals. Our automated pipeline outperforms traditional 2D crystallization methods in terms of throughput and reproducibility.
| S-EPMC3128831 | biostudies-literature
Project description:Single-layer two-dimensional (2D) nanomaterials exhibit physical and chemical properties which can be dynamically modulated through out-of-plane deformations. Existing methods rely on intricate micromechanical manipulations (e.g., poking, bending, rumpling), hindering their widespread technological implementation. We address this challenge by proposing an all-optical approach that decouples strain engineering from micromechanical complexities. This method leverages the forces generated by chiral light beams carrying orbital angular momentum (OAM). The inherent sense of twist of these beams enables the exertion of controlled torques on 2D monolayer materials, inducing tailored strain. This approach offers a contactless and dynamically tunable alternative to existing methods. As a proof-of-concept, we demonstrate control over the conductivity of graphene transistors using chiral light beams, showcasing the potential of this approach for manipulating properties in future electronic devices. This optical control mechanism holds promise in enabling the reconfiguration of devices through optically patterned strain. It also allows broader utilization of strain engineering in 2D nanomaterials for advanced functionalities in next-generation optoelectronic devices and sensors.
| S-EPMC11313125 | biostudies-literature
Project description:Chiral-induced spin selectivity (CISS) occurs when the chirality of the transporting medium selects one of the two spin ½ states to transport through the media while blocking the other. Monolayers of chiral organic molecules demonstrate CISS but are limited in their efficiency and utility by the requirement of a monolayer to preserve the spin selectivity. We demonstrate CISS in a system that integrates an inorganic framework with a chiral organic sublattice inducing chirality to the hybrid system. Using magnetic conductive-probe atomic force microscopy, we find that oriented chiral 2D-layered Pb-iodide organic/inorganic hybrid perovskite systems exhibit CISS. Electron transport through the perovskite films depends on the magnetization of the probe tip and the handedness of the chiral molecule. The films achieve a highest spin-polarization transport of up to 86%. Magnetoresistance studies in modified spin-valve devices having only one ferromagnet electrode confirm the occurrence of spin-dependent charge transport through the organic/inorganic layers.
| S-EPMC6897542 | biostudies-literature