A method for the detection of approximate molecular symmetry in crystal structures has been developed. The point-group symmetry is assigned to each molecule and the relevant symmetry elements can be visualized, superimposed on the molecule. The method has been validated against reference structures with exact symmetry subjected to small random perturbation.
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http://dx.doi.org/10.1107/s010876810001380x | DOI Listing |
Science
January 2025
Max Planck Institute for the Structure and Dynamics of Matter, Hamburg, Germany.
Chirality, a pervasive form of symmetry, is intimately connected to the physical properties of solids, as well as the chemical and biological activity of molecular systems. However, inducing chirality in a nonchiral material is challenging because this requires that all mirrors and all roto-inversions be simultaneously broken. Here, we show that chirality of either handedness can be induced in the nonchiral piezoelectric material boron phosphate (BPO) by irradiation with terahertz pulses.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Department of Ecology and Evolution, University of Chicago, Chicago, IL 60637.
Many proteins form paralogous multimers-molecular complexes in which evolutionarily related proteins are arranged into specific quaternary structures. Little is known about the mechanisms by which they acquired their stoichiometry (the number of total subunits in the complex) and heterospecificity (the preference of subunits for their paralogs rather than other copies of the same protein). Here, we use ancestral protein reconstruction and biochemical experiments to study historical increases in stoichiometry and specificity during the evolution of vertebrate hemoglobin (Hb), an αβ heterotetramer that evolved from a homodimeric ancestor after a gene duplication.
View Article and Find Full Text PDFSoft Matter
January 2025
Department of Materials Science, University of Patras, 26504 Patras, Greece.
Monte Carlo molecular simulations of curve-shaped rods show the propensity of such shapes to polymorphism revealing both smectic and polar nematic phases. The nematic exhibits a nanoscale modulated local structure characterized by a unique, polar, -symmetry axis that tightly spirals generating a mirror-symmetry-breaking organization of the achiral rods-form chirality. A comprehensive characterization of the polarity and its symmetries in the nematic phase confirms that the nanoscale modulation is distinct from the elastic deformations of a uniaxial nematic director in the twist-bend nematic phase.
View Article and Find Full Text PDFSoft Matter
January 2025
Department of Mechanical and Energy Engineering, Southern University of Science and Technology, Shenzhen, 518055, China.
We report an experimental study on how topological defects induced by cylindrical air inclusions in the ferroelectric nematic liquid crystal RM734 are influenced by ionic doping, including an ionic surfactant and ionic polymer. Our results show that subtle differences in molecular structure can lead to distinct surface alignments and topological defects. The ionic surfactant induces a planar alignment, with two -1/2 line defects adhering to the cylindrical bubble surface.
View Article and Find Full Text PDFAdv Mater
January 2025
School of Engineering, Westlake University, Hangzhou, 310030, China.
The epitaxial growth of molybdenum disulfide (MoS₂) on sapphire substrates enables the formation of single-crystalline monolayer MoS₂ with exceptional material properties on a wafer scale. Despite this achievement, the underlying growth mechanisms remain a subject of debate. The epitaxial interface is critical for understanding these mechanisms, yet its exact atomic configuration has previously been unclear.
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