The solvent-induced isomerization of silver thiolate clusters with symmetry transformation

2020 ◽  
Vol 56 (25) ◽  
pp. 3649-3652 ◽  
Author(s):  
Xu-Ran Chen ◽  
Ling Yang ◽  
Yu-Ling Tan ◽  
Hong Yu ◽  
Chun-Yan Ni ◽  
...  
Keyword(s):  
Room Temperature ◽  
Symmetry Transformation ◽  
Symmetry Transformations ◽  
Solvent Molecules

The solvent-induced isomerizations of Ag12 clusters with symmetry transformations were realized by changing the coordinated solvent molecules at room temperature.

A new one-dimensional CdIIcoordination polymer with a two-dimensional layered structure incorporating 2-[(1H-imidazol-1-yl)methyl]-1H-benzimidazole and benzene-1,2-dicarboxylate ligands

2016 ◽  
Vol 72 (6) ◽  
pp. 480-484 ◽  
Author(s):  
Qiu-Ying Huang ◽  
Xiao-Yi Lin ◽  
Xiang-Ru Meng
Keyword(s):  
Layered Structure ◽  
Room Temperature ◽  
Weak Interactions ◽  
Coordination Geometry ◽  
Dimensional Chain ◽  
Two Dimensional ◽  
One Dimensional ◽  
Heterocyclic Ligand ◽  
Rich Variety ◽  
Solvent Molecules

The N-heterocyclic ligand 2-[(1H-imidazol-1-yl)methyl]-1H-benzimidazole (imb) has a rich variety of coordination modes and can lead to polymers with intriguing structures and interesting properties. In the coordination polymercatena-poly[[cadmium(II)-bis[μ-benzene-1,2-dicarboxylato-κ4O1,O1′:O2,O2′]-cadmium(II)-bis{μ-2-[(1H-imidazol-1-yl)methyl]-1H-benzimidazole}-κ2N2:N3;κ2N3:N2] dimethylformamide disolvate], {[Cd(C8H4O4)(C11H10N4)]·C3H7NO}n, (I), each CdIIion exhibits an irregular octahedral CdO4N2coordination geometry and is coordinated by four O atoms from two symmetry-related benzene-1,2-dicarboxylate (1,2-bdic2−) ligands and two N atoms from two symmetry-related imb ligands. Two CdIIions are connected by two benzene-1,2-dicarboxylate ligands to generate a binuclear [Cd2(1,2-bdic)2] unit. The binuclear units are further connected into a one-dimensional chain by pairs of bridging imb ligands. These one-dimensional chains are further connected through N—H...O hydrogen bonds and π–π interactions, leading to a two-dimensional layered structure. The dimethylformamide solvent molecules are organized in dimeric pairsviaweak interactions. In addition, the title polymer exhibits good fluorescence properties in the solid state at room temperature.

Investigations on the polymorphism and pseudopolymorphism of clobetasone butyrate

2011 ◽  
Vol 76 (5) ◽  
pp. 553-566
Author(s):  
Christian Näther ◽  
Inke Jeß
Keyword(s):  
Room Temperature ◽  
Polymorphic Form ◽  
Stable Form ◽  
Scanning Calorimetry ◽  
Amorphous Form ◽  
Space Group ◽  
Dsc Measurements ◽  
Independent Molecules ◽  
Solvent Molecules ◽  
Similar Conformation

Clobetasone butyrate was investigated for polymorphism and pseudopolymorphism. Solvent mediated conversion experiments reveal that the commercially available form I represent the thermodynamically most stable form at room temperature and DSC measurements shows that it should also be the most stable form until melting. Form I crystallizes in space groupP212121with three crystallographically independent molecules of similar conformation. From methanol an additional pseudo polymorphic form was discovered. In the crystal structure (space groupP212121) the solvent molecules are connected to the clobetasone butyrate molecules by O–H···O hydrogen bonding. Investigations of the solvate using thermogravimetry, differential thermoanalysis as well as differential scanning calorimetry proves, that on solvent removal an amorphous form is obtained that crystallizes into form I on further heating.

The methylgallium-2-carboxylatobenzimidazolato hexamer, [MeGa·C8H4N2O2]6·C6H6·(Me2C6H4)2; synthesis and X-ray crystal structure

1999 ◽  
Vol 77 (4) ◽  
pp. 434-438 ◽  
Author(s):  
Steven J Rettig ◽  
Alan Storr ◽  
James Trotter
Keyword(s):  
Crystal Structure ◽  
Carboxylic Acid ◽  
Room Temperature ◽  
Direct Methods ◽  
Membered Ring ◽  
Coordination Geometry ◽  
Temperature Reaction ◽  
Full Matrix ◽  
X Ray ◽  
Solvent Molecules

The room-temperature reaction of Me3Ga with benzimidazole 2-carboxylic acid in xylene solvent has yielded a novel crystalline hexameric gallium compound with "MeGa" moieties bridged by the doubly depronotated ligand precursor. Crystals of [MeGa(4,5-benzimidazolato-2-carboxylato)]6·(C6H6)·(m-Me2C6H4)2 are monoclinic, a = 18.091(2), b = 17.094(2), c = 13.2215(5) Å, Z = 2, space group C2/m. The structure was solved by direct methods and refined by full-matrix least-squares procedures to R (F, I [Formula: see text] 3σ(I)) = 0.064 (Rw (F2, all data) = 0.134). The hexameric Ga complex contains a six-membered ring of Ga atoms, bridged by the benzimidazolate ligands with the benzo rings projecting alternately above and below the Ga plane, thus forming a ball-shaped molecule. The complex could have ideal D3d symmetry, but it contains an encapsulated molecule of benzene, which distorts the regularity of the Ga6 hexagon, and reduces the symmetry of the complex to the crystallographically observed C2h. The coordination geometry at each of the two independent GaO2N2C centres approximates a trigonal bipyramid, with a N2C trigonal plane, and the O atoms above and below; average dimensions are Ga-O = 2.176(2), Ga-N = 1.973(3), Ga-C = 1.927(5) Å, O-Ga-O = 165°. The unit cell also contains four m-xylene solvent molecules (outside the molecular cage).Key words: gallium, crystal structure, benzene intercalate, benzimidazolecarboxylic acid.

scholarly journals (η6-Benzene)(carbonato-κ2O,O′)[dicyclohexyl(naphthalen-1-ylmethyl)phosphane-κP]ruthenium(II) chloroform trisolvate

2014 ◽  
Vol 70 (7) ◽  
pp. m272-m273
Author(s):  
Saravanan Gowrisankar ◽  
Helfried Neumann ◽  
Anke Spannenberg ◽  
Matthias Beller
Keyword(s):  
Hydrogen Bonding ◽  
Metal Complex ◽  
Room Temperature ◽  
Crystal Packing ◽  
The Other ◽  
Asymmetric Unit ◽  
Carbonate Group ◽  
Acta Cryst ◽  
Hydrogen Bonding Interactions ◽  
Solvent Molecules

The title compound, [Ru(CO3)(η6-C6H6){(C6H11)2P(CH2C10H7)}]·3CHCl3, was synthesized by carbonation of [RuCl2(η6-C6H6){(C6H11)2P(CH2C10H7)}] with NaHCO3in methanol at room temperature. The RuIIatom is surrounded by a benzene ligand, a chelating carbonate group and a phosphane ligand in a piano-stool configuration. The crystal packing is consolidated by C—H...O and C—H...Cl hydrogen-bonding interactions between adjacent metal complexes and between the complexes and the solvent molecules. The asymmetric unit contains one metal complex and three chloroform solvent molecules of which only one was modelled. The estimated diffraction contributions of the other two strongly disordered chloroform solvent molecules were substracted from the observed diffraction data using the SQUEEZE procedure inPLATON[Spek (2009).Acta Cryst.D65, 148–155].

Non-local symmetries and the nth finite symmetry transformations for the (2+1)-dimensional Korteweg–de Vries equation

2020 ◽  
pp. 2050432
Author(s):  
Xiazhi Hao ◽  
Xiaoyan Li
Keyword(s):  
Spectral Function ◽  
Soliton Solution ◽  
Vries Equation ◽  
Kdv Equation ◽  
Symmetry Transformation ◽  
De Vries ◽  
Symmetry Transformations ◽  
Non Local ◽  
Local Symmetries

Non-local symmetries in forms of square spectral function and residue over the (2+1)-dimensional Korteweg–de Vries (KdV) equation are studied in some detail. Then, we present [Formula: see text]-soliton solution to this equation with the help of symmetry transformation.

The radiation chemistry of glassy n -propanol

1970 ◽  
Vol 320 (1540) ◽  
pp. 1-22 ◽  
Keyword(s):  
Gas Chromatography ◽  
Low Temperature ◽  
Room Temperature ◽  
Equilibrium Configuration ◽  
Radiation Chemistry ◽  
First Order ◽  
Gaseous Products ◽  
Radical Concentration ◽  
Thermal Bleaching ◽  
Solvent Molecules

The irradiation of glassy n -propanol at 77 K with 60 Co γ -rays has been investigated by the use of low temperature optical and e.s.r. spectroscopy to identify intermediates and gas chromatography to measure yields of gaseous products. Trapped electrons (e t - ) are formed with a yield G (e t - ) = 1.7 ± 0.2. Controlled warming and illumination with light λ > λ max suggest that electrons are initially immobilized in cavities surrounded by a non-equilibrium configuration of solvent molecules. The decay of e t - at 100 to 110 K is first-order, the Arrhenius parameters being lg A (s -1 ) = 12.5 ± 1.5 and E a = 31.3 ± 2.9kJ/mol. For photobleaching with light λ 509nm , ( ɸє ) 509 = 460 ± 501 mol -1 cm -1 independent of the fraction of e t - bleached. Unlike thermal bleaching, photobleaching does not change the total radical concentration as observed by e.s.r. The thermal and photolytic destruction of e t - are explained by the following reactions: e t - → EtCH 2 O - + H 2 e t - + hv →EtCHOH + EtCH 2 O - + H 2 →EtCHO - . + H 2 , and the effects of additives are discussed. The thermal decay of the u.v. absorption after complete photobleaching of e t - showed evidence of a species stable at 120 K but which decayed slowly at room temperature. An assignment of the u.v. absorptions to the species EtCHOH and EtCHO - is discussed. Some results are presented on the photolysis of γ -irradiated glasses with light of λ 254 nm.

The Visible Absorption Spectrum of Bromine in Solution

1948 ◽  
Vol 1 (4) ◽  
pp. 472 ◽  
Author(s):  
NS Bayliss ◽  
ARH Cole ◽  
BG Green
Keyword(s):  
Absorption Spectrum ◽  
Sulphuric Acid ◽  
Room Temperature ◽  
Vibrational Energy ◽  
Energy Levels ◽  
Visible Absorption Spectrum ◽  
Visible Absorption ◽  
Solvent Molecules ◽  
Vibrational Energy Levels ◽  
Associated Solvents

The visible absorption spectrum of bromine was measured in n-hexane (a normal solvent) and in concentrated sulphuric acid (at room temperature and at -70� C.), phosphoric acid, and ethanol (at -70� C.) as associated solvents. The absorption continuum at 4150 A. in the gas is displaced slightly to the red in n-hexane although other normal solvents may displace it to the violet. The displacement to the violet is greater in associated solvents, ranging from 650 cm.-l in sulphuric acid to over 2000 cm.-1 in ethanol. The displacement in sulphuric acid glass at -70� C, is nearly double the value at 18� C. The displacements in associated solvents are explained in terms of the effect of the semi-rigid cage of solvent molecules surrounding each bromine molecule, and the assumption of " solvates " is unnecessary and undesirable. The spectra in solution are between 40 and 70 per cent. more intense than in the gas, about double the increase that would be predicted by Chako's treatment of the effect of Lorentz-Lorenz forces. The differences in the shape and Emax between solutions in sulphuric acid at 18� C. and at -70� C. are due to the different statistical distribution of bromine molecules between the vibrational energy levels.

The Number of Symmetry Transformation of Convex Regular Polytopes in the n - Space

2018 ◽  
pp. 74-102
Keyword(s):  
Symmetry Transformation ◽  
Regular Polytopes ◽  
Symmetry Transformations

The number of symmetry transformations of regular polytopes of dimension n (n - cubes, n - simplexes, n - cross polytopes) are considered, using symmetry transformation of their facets. In this chapter, it is investigated how a certain symmetry transformation of the facet leads to the transformation of the symmetry of the polytope, under the condition of continuity of the polytope as a whole. It is established that the number of symmetry transformations of a regular n - polytope is equal to the product of the number of symmetry transformations of the facet of the corresponding polytope by the number of facets in this polytope.

Morpheme structure constraints on two-handed signs in American Sign Language

2003 ◽  
Vol 6 (2) ◽  
pp. 123-205 ◽  
Author(s):  
Donna Jo Napoli ◽  
Jeff Wu
Keyword(s):  
American Sign Language ◽  
Sign Language ◽  
Symmetry Transformation ◽  
Symmetry Condition ◽  
Dominant Hand ◽  
American Sign ◽  
The Third ◽  
Dominance Condition ◽  
Symmetry Transformations ◽  
Different Shapes

In ASL, two-handed signs fall into three major sets. In one set the hands have different shapes and either only the dominant hand moves or the hands move as a unit. Battison’s Dominance Condition was intended to account for the fact that the non-dominant hand typically assumes an unmarked shape when it is stationary. However, we show that the non-dominant hand does this even when the hands move as a unit. In the second set the hands have the same shape and only the dominant hand moves. These signs are unrestricted for handshape. In the third set the hands have the same shape and both move. Battison’s Symmetry Condition was intended to account for restrictions on the parameters of these signs. We argue that four basic types of symmetry transformations occur, with various complications: reflection, rotation, translation, and glide reflection, all of which call for conditions specific to them, and lead to an overriding condition on movement in symmetry transformation signs. The conditions uncovered here might be morpheme structure constraints or, instead, simply follow from physiological limitations of hands in motion.

scholarly journals Supervariable and BRST Approaches to a Reparameterization Invariant Nonrelativistic System

2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
A. K. Rao ◽  
A. Tripathi ◽  
R. P. Malik
Keyword(s):  
Free Particle ◽  
Brst Symmetry ◽  
Symmetry Transformation ◽  
Present System ◽  
Evolution Parameter ◽  
Gauge Fixing ◽  
Symmetry Transformations ◽  
Diffeomorphism Symmetry ◽  
Popov Ghost ◽  
Relativistic Particles

We exploit the theoretical strength of the supervariable and Becchi-Rouet-Stora-Tyutin (BRST) formalisms to derive the proper (i.e., off-shell nilpotent and absolutely anticommuting) (anti-)BRST symmetry transformations for the reparameterization invariant model of a nonrelativistic (NR) free particle whose space x and time t variables are a function of an evolution parameter τ . The infinitesimal reparameterization (i.e., 1D diffeomorphism) symmetry transformation of our theory is defined w.r.t. this evolution parameter τ . We apply the modified Bonora-Tonin (BT) supervariable approach (MBTSA) as well as the (anti)chiral supervariable approach (ACSA) to BRST formalism to discuss various aspects of our present system. For this purpose, our 1D ordinary theory (parameterized by τ ) is generalized onto a 1 , 2 -dimensional supermanifold which is characterized by the superspace coordinates Z M = τ , θ , θ ¯ where a pair of the Grassmannian variables satisfy the fermionic relationships: θ 2 = θ ¯ 2 = 0 , θ   θ ¯ + θ ¯   θ = 0 , and τ is the bosonic evolution parameter. In the context of ACSA, we take into account only the 1 , 1 -dimensional (anti)chiral super submanifolds of the general 1 , 2 -dimensional supermanifold. The derivation of the universal Curci-Ferrari- (CF-) type restriction, from various underlying theoretical methods, is a novel observation in our present endeavor. Furthermore, we note that the form of the gauge-fixing and Faddeev-Popov ghost terms for our NR and non-SUSY system is exactly the same as that of the reparameterization invariant SUSY (i.e., spinning) and non-SUSY (i.e., scalar) relativistic particles. This is a novel observation, too.

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