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

X-ray crystallographic analysis has revealed that the light-sensitive form (A) and the light-stable form (A') of tetrabenzoylethylene are not valence tautomers but are two crystalline modifications of the same substance. The difference in the stability of these forms to light appears to be a consequence of their different molecular conformations and packing in the solid state. The molecular conformation of the A form is represented by (8) and that of the A' form by (9). The related tetraacetylethylene has the conformation (10) in the solid state. X-ray crystallographic analysis has also revealed that the photolysis product (B) of tetrabenzoylethylene is 4-phenoxy-3,4,6-triphenyl-1H,4H-furo[3,4-c]-furan-1-one (11). �� The crystal structures of (8), (9), (10) and (11) were determined by X-ray diffraction: diffractometer data at 295 K were refined by least-squares techniques to residuals of 0.064 (2161 'observed' reflections) for (8), 0.057 (1310) for (9), 0.049 (1295) for (10) and 0.061 (1639) for (11). Crystals of (8) are monoclinic, P21/n, a 8.775(5), b 17.352(9), c 30.985(8)Ǻ, β 93.01(3)°, Z 8. Crystals of (9) which contain carbon disulfide are monoclinic, A2/a, a 21.21(2), b 6.181(4), c 20.35(2) Ǻ, β 102.77(7)°, Z 4. Crystals of (10) are monoclinic, P21/n, a 7.540(2), b 4.392(2), c 14.770(4) Ǻ, β 96.29(2)°, Z 2. Crystals of (11) are monoclinic, P1/n, a 14.820(4), b 15.000(3), c 10.819(4)Ǻ, β 106.02(2)°, Z 4.

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Stabilization of networked switched affine systems with event-triggered strategy

Transactions of the Institute of Measurement and Control ◽

10.1177/01423312211021304 ◽

2021 ◽

pp. 014233122110213

Author(s):

Dandan Li ◽

Zhiqiang Zuo ◽

Yijing Wang

Keyword(s):

Affine Systems ◽

Switching Law ◽

Event Time ◽

Sliding Motion ◽

State Dependent ◽

Event Triggering ◽

Stability Issue ◽

The Stability ◽

Event Based ◽

Selection Of

Using an event-based switching law, we address the stability issue for continuous-time switched affine systems in the network environment. The state-dependent switching law in terms of the region function is firstly developed. We combine the region function with the event-triggering mechanism to construct the switching law. This can provide more candidates for the selection of the next activated subsystem at each switching instant. As a result, it is possible for us to activate the appropriate subsystem to avoid the sliding motion. The Zeno behavior for the switched affine system can be naturally ruled out by guaranteeing a positive minimum inter-event time between two consecutive executions of the event-triggering threshold. Finally, two numerical examples are given to demonstrate the effectiveness of the proposed method.

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

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20031233 ◽

2003 ◽

Vol 68 (7) ◽

pp. 1233-1242 ◽

Cited By ~ 6

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.

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

Dalton Transactions ◽

10.1039/c6dt03302d ◽

2016 ◽

Vol 45 (46) ◽

pp. 18522-18531 ◽

Cited By ~ 2

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.

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Molecular Conformation and Intermolecular Interactions in the Crystal Structures of Free-Base 5,15-Diarylporphyrins

Crystal Growth & Design ◽

10.1021/cg010029u ◽

2002 ◽

Vol 2 (1) ◽

pp. 27-39 ◽

Cited By ~ 16

Author(s):

Andrew D. Bond ◽

Neil Feeder ◽

James E. Redman ◽

Simon J. Teat ◽

Jeremy K. M. Sanders

Keyword(s):

Crystal Structures ◽

Intermolecular Interactions ◽

Molecular Conformation ◽

Free Base

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The search for formal electrostatic effects on molecular conformation and crystal packing: crystal structure of 2,2′′-disubstituted (HversusPPh2) 1,1′-(1,2-phenylene)bis(3-methyl-1H-imidazol-3-ium) bis(trifluoromethanesulfonate)

Acta Crystallographica Section C Structural Chemistry ◽

10.1107/s2053229616002576 ◽

2016 ◽

Vol 72 (3) ◽

pp. 198-202

Author(s):

Carine Duhayon ◽

Yves Canac ◽

Laurent Dubrulle ◽

Carine Maaliki ◽

Remi Chauvin

Keyword(s):

Crystal Structure ◽

Electrostatic Interactions ◽

Molecular Conformation ◽

Crystal Packing ◽

Relative Orientation ◽

Electron Delocalization ◽

Electrostatic Effects ◽

Conformational Freedom ◽

The Stability ◽

Bond Character

Electrostatic interactions between localized integral charges make the stability and structure of highly charged small and rigid organics intriguing. Can σ/π-electron delocalization compensate reduced conformational freedom by lowering the repulsion between identical charges? The crystal structure of the title salt, C14H16N42+·2CF3SO3−, (2), is described and compared with that of the 2,2′′-bis(diphenylphosphanyl) derivative, (4). The conformations of the dications and their interactions with neighbouring trifluoromethanesulfonate anions are first analyzed from the standpoint of formal electrostatic effects. Neither cation exhibits any geometrical strain induced by the intrinsic repulsion between the positive charges. In contrast, the relative orientation of the imidazolium rings [i.e. antifor (2) andsynfor (4)] is controlled by different configurations of the interactions with the closest trifluoromethanesulfonate anions. The long-range arrangement is also found to be specific: beyond the formal electrostatic packing, C—H...O and C—H...F contacts have no definite `hydrogen-bond' character but allow the delineation of layers, which are either pleated or flat in the packing of (2) or (4), respectively.

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

Molecules ◽

10.3390/molecules26237178 ◽

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.

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