scholarly journals Assembly of silver Trigons into a buckyball-like Ag180nanocage

2017 ◽  
Vol 114 (46) ◽  
pp. 12132-12137 ◽  
Author(s):  
Zhi Wang ◽  
Hai-Feng Su ◽  
Yuan-Zhi Tan ◽  
Stan Schein ◽  
Shui-Chao Lin ◽  
...  
Keyword(s):  
Complex Structure ◽  
Point Group ◽  
Group Symmetry ◽  
Ionization Mass ◽  
Design Synthesis ◽  
Archimedean Solid ◽  
Large Numbers ◽  
Virus Capsids ◽  
Archimedean Tiling

Buckminsterfullerene (C60) represents a perfect combination of geometry and molecular structural chemistry. It has inspired many creative ideas for building fullerene-like nanopolyhedra. These include other fullerenes, virus capsids, polyhedra based on DNA, and synthetic polynuclear metal clusters and cages. Indeed, the regular organization of large numbers of metal atoms into one highly complex structure remains one of the foremost challenges in supramolecular chemistry. Here we describe the design, synthesis, and characterization of a Ag180nanocage with 180 Ag atoms as 4-valent vertices (V), 360 edges (E), and 182 faces (F)––sixty 3-gons, ninety 4-gons, twelve 5-gons, and twenty 6-gons––in agreement with Euler’s rule V − E + F = 2. If each 3-gon (or silver Trigon) were replaced with a carbon atom linked by edges along the 4-gons, the result would be like C60, topologically a truncated icosahedron, an Archimedean solid with icosahedral (Ih) point-group symmetry. If C60can be described mathematically as a curling up of a 6.6.6 Platonic tiling, the Ag180cage can be described as a curling up of a 3.4.6.4 Archimedean tiling. High-resolution electrospray ionization mass spectrometry reveals that {Ag3}nsubunits coexist with the Ag180species in the assembly system before the final crystallization of Ag180, suggesting that the silver Trigon is the smallest building block in assembly of the final cage. Thus, we assign the underlying growth mechanism of Ag180to the Silver-Trigon Assembly Road (STAR), an assembly path that might be further employed to fabricate larger, elegant silver cages.

scholarly journals Symmetry-extended counting rules for periodic frameworks

2014 ◽  
Vol 372 (2008) ◽  
pp. 20120029 ◽  
Author(s):  
S. D. Guest ◽  
P. W. Fowler
Keyword(s):  
Point Group ◽  
Factor Group ◽  
Unit Cell ◽  
Group Symmetry ◽  
Point Group Symmetry ◽  
Space Group ◽  
Counting Rules ◽  
Periodic Frameworks ◽  
Explicit Expressions

A symmetry-adapted version of the Maxwell rule appropriate to periodic bar-and-joint frameworks is obtained, and is further extended to body-and-joint systems. The treatment deals with bodies and forces that are replicated in every unit cell, and uses the point group isomorphic to the factor group of the space group of the framework. Explicit expressions are found for the numbers and symmetries of detectable mechanisms and states of self-stress in terms of the numbers and symmetries of framework components. This approach allows detection and characterization of mechanisms and states of self-stress in microscopic and macroscopic materials and meta-materials. Illustrative examples are described. The notion of local isostaticity of periodic frameworks is extended to include point-group symmetry.

scholarly journals Spherical polar Fourier assembly of protein complexes with arbitrary point group symmetry

2016 ◽  
Vol 49 (1) ◽  
pp. 158-167 ◽  
Author(s):  
David W. Ritchie ◽  
Sergei Grudinin
Keyword(s):  
Protein Complexes ◽  
Complex Structure ◽  
Point Group ◽  
Arbitrary Point ◽  
Group Symmetry ◽  
Test Cases ◽  
Point Group Symmetry ◽  
Group Symmetries ◽  
The Given ◽  
Ab Inito

A novel fast Fourier transform-basedab initodocking algorithm calledSAMis presented, for building perfectly symmetrical models of protein complexes with arbitrary point group symmetry. The basic approach uses a novel and very fast one-dimensional symmetry-constrained spherical polar Fourier search to assemble cyclicCnsystems from a given protein monomer. Structures with higher-order (Dn,T,OandI) point group symmetries may be built using a subsequent symmetry-constrained Fourier domain search to assemble trimeric sub-units. The results reported here show that theSAMalgorithm can correctly assemble monomers of up to around 500 residues to produce a near-native complex structure with the given point group symmetry in 17 out of 18 test cases. TheSAMprogram may be downloaded for academic use at http://sam.loria.fr/.

Hydrothermal Synthesis and Solid-State Laser Refrigeration of Ytterbium-Doped Potassium Lutetium Fluoride (KLF) Microcrystals

2020 ◽  
Author(s):  
Xiaojing Xia ◽  
Anupum Pant ◽  
Xuezhe Zhou ◽  
Elena Dobretsova ◽  
Alex Bard ◽  
...  
Keyword(s):  
Hydrothermal Synthesis ◽  
Solid State ◽  
Information Science ◽  
Point Group ◽  
Solid State Laser ◽  
Lanthanide Ions ◽  
Group Symmetry ◽  
Luminescence Spectra ◽  
Crystalline Phases ◽  
State Laser

Fluoride crystals, due to their low phonon energies, are attractive hosts of trivalent lanthanide ions for applications in upconverting phosphors, quantum information science, and solid-state laser refrigeration. In this article, we report the rapid, low-cost hydrothermal synthesis of potassium lutetium fluoride (KLF) microcrystals for applications in solid-state laser refrigeration. Four crystalline phases were synthesized, namely orthorhombic K<sub>2</sub>LuF<sub>5</sub> (Pnma), trigonal KLuF<sub>4</sub> (P3<sub>1</sub>21), orthorhombic KLu<sub>2</sub>F<sub>7</sub> (Pna2<sub>1</sub>), and cubic KLu<sub>3</sub>F<sub>10</sub> (Fm3m), with each phase exhibiting unique microcrystalline morphologies. Luminescence spectra and emission lifetimes of the four crystalline phases were characterized based on the point-group symmetry of trivalent cations. Laser refrigeration was measured by observing both the optomechanical eigenfrequencies of microcrystals on cantilevers in vacuum, and also the Brownian dynamics of optically trapped microcrystals in water. Among all four crystalline phases, the most significant cooling was observed for 10%Yb:KLuF<sub>4</sub> with cooling of 8.6 $\pm$ 2.1 K below room temperature. Reduced heating was observed with 10%Yb:K<sub>2</sub>LuF<sub>5</sub>

Exploring the characterization of Ni doped MgO nanoparticles using co-precipitation method

2020 ◽  
Vol 3 (1) ◽  
pp. 30-33
Author(s):  
Muthulakshmi M ◽  
Madhumitha G
Keyword(s):  
Magnesium Oxide ◽  
Analytical Techniques ◽  
Nickel Chloride ◽  
Precipitation Method ◽  
Crystalline Powder ◽  
High Melting Point ◽  
Design Synthesis ◽  
Mgo Nanoparticles ◽  
Co Precipitation

Nanotechnology is a field of applied science focused on design, synthesis and characterization of nanomaterials. The nickel and magnesium have improved their applications in transparent electrodes and nano electronics. In addition, magnesium oxide has moisture resistance and high melting point properties. In the present work has been carried out in the development of green crystalline powder of nickel doped magnesium oxide nanoparticles by Co-precipitation method, from the mixture of nickel chloride and magnesium chloride with KOH as solvent. From the XRD results, crystalline size of the particle can be observed. Spherical structure of Ni doped MgO nanoparticles were indicated by SEM results and powdered composition of samples were obtained from FTIR. EDAX represents the peak composition of the nanoparticle. The above analytical techniques have confirmed that the Ni doped MgO nanoparticles obtained from the mixture of NiCl2 and MgCl2.

scholarly journals Multiplicity, Parity and Angular Momentum of a Cooper Pair in Unconventional Superconductors of D4h Symmetry: Sr2RuO4 and Fe-Pnictide Materials

Symmetry ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1435
Author(s):  
Victor G. Yarzhemsky
Keyword(s):  
Angular Momentum ◽  
Cooper Pair ◽  
Point Group ◽  
Group Symmetry ◽  
Cooper Pairs ◽  
Group Approach ◽  
Angular Momentum Projection ◽  
Space Group ◽  
Unconventional Superconductors ◽  
Even Pairs

Sr2RuO4 and Fe-pnictide superconductors belong to the same point group symmetry D4h. Many experimental data confirm odd pairs in Sr2RuO4 and even pairs in Fe-pnictides, but opposite conclusions also exist. Recent NMR results of Pustogow et al., which revealed even Cooper pairs in Sr2RuO4, require reconsideration of symmetry treatment of its SOP (superconducting order parameter). In the present work making use of the Mackey–Bradley theorem on symmetrized squares, a group theoretical investigation of possible pairing states in D4h symmetry is performed. It is obtained for I4/mmm , i.e., space group of Sr2RuO4, that triplet pairs with even spatial parts are possible in kz direction and in points M and Y. For the two latter cases pairing of equivalent electrons with nonzero total momentum is proposed. In P4/nmm space group of Fe- pnictides in point M, even and odd pairs are possible for singlet and triplet cases. It it shown that even and odd chiral states with angular momentum projection m=±1 have nodes in vertical planes, but Eg is nodal , whereas Eu is nodeless in the basal plane. It is also shown that the widely accepted assertion that the parity of angular momentum value is directly connected with the spatial parity of a pair is not valid in a space-group approach to the wavefunction of a Cooper pair.

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