Exo-bonded six-membered heterocycle in the crystal structures of RE7Co2Ge4(RE = La–Nd)

2016 ◽  
Vol 45 (46) ◽  
pp. 18522-18531 ◽  
Author(s):  
Siméon Ponou ◽  
Sven Lidin
Keyword(s):  
Crystal Structures ◽  
Strong Interactions ◽  
The Stability ◽  
Membered Heterocycle

The stability of the heterocyclic {Co4Ge6} clusters in RE7Co2Ge4(RE = La–Nd) is determined by strong interactions with the surrounding RE atoms in the structures.

Electrical Conductivity of Chloro(phenyl)glyoxime and Its Co(II), Ni(II) and Cu(II) Complexes

2003 ◽  
Vol 68 (7) ◽  
pp. 1233-1242 ◽  
Author(s):  
Orhan Turkoglu ◽  
Mustafa Soylak ◽  
Ibrahim Belenli
Keyword(s):  
Electrical Conductivity ◽  
Temperature Dependence ◽  
Electric Conductivity ◽  
Crystal Structures ◽  
Elemental Analysis ◽  
Analysis Data ◽  
Elemental Analysis Data ◽  
The Stability ◽  
Xrd Patterns ◽  
Metal Ligand

Chloro(phenyl)glyoxime, a vicinal dioxime, and its Ni(II), Cu(II) and Co(II) complexes were prepared. XRD patterns of the complexes point to similar crystal structures. IR and elemental analysis data revealed the 1:2 metal-ligand ratio in the complexes. The Co(II) complex is a dihydrate. Temperature dependence of electrical conductivity of the solid ligand and its complexes was measured in the temperature range 25-250 °C; it ranged between 10-14-10-6 Ω-1 cm-1 and increased with rising temperature. The activation energies were between 0.61-0.80 eV. The Co(II) complex has lower electric conductivity than the Ni(II) and Cu(II) complexes. This difference in the conductivity has been attributed to differences in the stability of the complexes.

Invited review: Importance of animal health and welfare for the stability of the three pillars of sustainability of livestock systems

2016 ◽  
Vol 7 (2) ◽  
pp. 208-214
Author(s):  
P. Chemineau
Keyword(s):  
Animal Welfare ◽  
Production Systems ◽  
Animal Health ◽  
Holistic Approach ◽  
Population Increase ◽  
Strong Interactions ◽  
Essential Components ◽  
The Future ◽  
The Stability ◽  
Livestock Systems

The future livestock systems at the world level will have to produce more in the perspective of the population increase in the next 30 years, whereas reducing their environmental footprint and addressing societal concerns. In that perspective, we may wonder if animal health and animal welfare, which are two essential components of production systems, may play an important role in the stability of the three pillars of sustainability of the livestock systems. We already know that objectives driven by economy, environment and society may modify animal welfare and animal health, but is the reverse true? The answer is yes and in 11 cases out of 12 of the matrix health-welfare×3 pillars of sustainability×positive or negative change, we have many examples indicating that animal health and animal welfare are able to modify, positively or negatively, the three pillars of sustainability. Moreover, we also have good examples of strong interactions between health and welfare. These elements play in favour of an holistic approach at the farm level and of a multicriterial definition of what could be the sustainable systems of animal production in the future which will respect animal welfare and maintain a good animal health.

scholarly journals Quantum Mechanical-Based Stability Evaluation of Crystal Structures for HIV-Targeted Drug Cabotegravir

Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7178
Author(s):  
Yanqiang Han ◽  
Hongyuan Luo ◽  
Qianqian Lu ◽  
Zeying Liu ◽  
Jinyun Liu ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Ab Initio ◽  
Crystal Structures ◽  
Structure Prediction ◽  
Hiv Infections ◽  
Integrase Inhibitor ◽  
Hiv Integrase ◽  
Stability Evaluation ◽  
The Stability ◽  
Long Acting

The long-acting parenteral formulation of the HIV integrase inhibitor cabotegravir (GSK744) is currently being developed to prevent HIV infections, benefiting from infrequent dosing and high efficacy. The crystal structure can affect the bioavailability and efficacy of cabotegravir. However, the stability determination of crystal structures of GSK744 have remained a challenge. Here, we introduced an ab initio protocol to determine the stability of the crystal structures of pharmaceutical molecules, which were obtained from crystal structure prediction process starting from the molecular diagram. Using GSK744 as a case study, the ab initio predicted that Gibbs free energy provides reliable further refinement of the predicted crystal structures and presents its capability for becoming a crystal stability determination approach in the future. The proposed work can assist in the comprehensive screening of pharmaceutical design and can provide structural predictions and stability evaluation for pharmaceutical crystals.

scholarly journals Joint crystallization of KCuAl[PO4]2 and K(Al,Zn)2[(P,Si)O4]2: crystal chemistry and mechanism of formation of phosphate-silicate epitaxial heterostructure

2020 ◽  
Vol 76 (3) ◽  
pp. 483-491
Author(s):  
Olga Yakubovich ◽  
Galina Kiriukhina ◽  
Larisa Shvanskaya ◽  
Anatoliy Volkov ◽  
Olga Dimitrova
Keyword(s):  
Crystal Structures ◽  
Active Material ◽  
Structure Type ◽  
Structural Features ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electrochemically Active ◽  
Phosphate Silicate ◽  
The Stability ◽  
Small Channels

Two novel phases, potassium copper aluminium bis(phosphate), KCuAl[PO4]2 (I), and potassium zinc aluminium bis(phosphate-silicate), K(Al,Zn)2[(P,Si)O4]2 (II), were obtained in one hydrothermal synthesis experiment at 553 K. Their crystal structures have been studied using single-crystal X-ray diffraction. (I) is a new member of the A + M 2+ M 3+[PO4]2 family. Its open 3D framework built by AlO5 and PO4 polyhedra includes small channels populated by columns of CuO6 octahedra sharing edges, and large channels where K+ ions are deposited. It is assumed that the stability of this structure type is due to the pair substitution of Cu/Al with Ni/Fe, Co/Fe or Mg/Fe in different representatives of the series. From the KCuAl[PO4]2 structural features, one may suppose it is a potentially electrochemically active material and/or possible low-temperature antiferromagnet. In accordance with results obtained from X-ray diffraction data, using scanning electron microscopy, microprobe analysis and detailed crystal chemical observation, (II) is considered as a product of epitaxial intergrowth of phosphate KAlZn[PO4]2 and silicate KAlSi[SiO4]2 components having closely similar crystal structures. The assembly of `coherent intergrowth' is described in the framework of a single diffraction pattern.

Regulating the stability of 2D crystal structures using an oxidation state-dependent molecular conformation

2006 ◽  
pp. 2320 ◽  
Author(s):  
Jonathan P. Hill ◽  
Yutaka Wakayama ◽  
Wolfgang Schmitt ◽  
Tohru Tsuruoka ◽  
Takashi Nakanishi ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Oxidation State ◽  
Molecular Conformation ◽  
State Dependent ◽  
The Stability

scholarly journals The identity of the active site of oxalate decarboxylase and the importance of the stability of active-site lid conformations1

2007 ◽  
Vol 407 (3) ◽  
pp. 397-406 ◽  
Author(s):  
Victoria J. Just ◽  
Matthew R. Burrell ◽  
Laura Bowater ◽  
Iain McRobbie ◽  
Clare E. M. Stevenson ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Active Site ◽  
Structural Information ◽  
Side Reaction ◽  
Oxalate Oxidase ◽  
Decarboxylase Activity ◽  
Oxalate Decarboxylase ◽  
Catalytically Active ◽  
The Stability ◽  
Kinetics Of

Oxalate decarboxylase (EC 4.1.1.2) catalyses the conversion of oxalate into carbon dioxide and formate. It requires manganese and, uniquely, dioxygen for catalysis. It forms a homohexamer and each subunit contains two similar, but distinct, manganese sites termed sites 1 and 2. There is kinetic evidence that only site 1 is catalytically active and that site 2 is purely structural. However, the kinetics of enzymes with mutations in site 2 are often ambiguous and all mutant kinetics have been interpreted without structural information. Nine new site-directed mutants have been generated and four mutant crystal structures have now been solved. Most mutants targeted (i) the flexibility (T165P), (ii) favoured conformation (S161A, S164A, D297A or H299A) or (iii) presence (Δ162–163 or Δ162–164) of a lid associated with site 1. The kinetics of these mutants were consistent with only site 1 being catalytically active. This was particularly striking with D297A and H299A because they disrupted hydrogen bonds between the lid and a neighbouring subunit only when in the open conformation and were distant from site 2. These observations also provided the first evidence that the flexibility and stability of lid conformations are important in catalysis. The deletion of the lid to mimic the plant oxalate oxidase led to a loss of decarboxylase activity, but only a slight elevation in the oxalate oxidase side reaction, implying other changes are required to afford a reaction specificity switch. The four mutant crystal structures (R92A, E162A, Δ162–163 and S161A) strongly support the hypothesis that site 2 is purely structural.

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