Crystal Structures of Two New Cyclosporin Clathrates

2000 ◽  
Vol 65 (12) ◽  
pp. 1950-1958 ◽  
Author(s):  
Michal Hušák ◽  
Bohumil Kratochvíl ◽  
Ivana Císařová ◽  
Alexandr Jegorov
Keyword(s):  
Crystal Structures ◽  
Methyl Ether ◽  
Van Der Waals ◽  
Van Der Waals Interactions ◽  
Solvent Molecules ◽  
Butyl Methyl Ether

Two isomorphous clathrates formed by dihydrocyclosporin A or cyclosporin V with tert-butyl methyl ether are reported and compared with the structures of related P21-symmetry cyclosporin clathrates. The cyclosporin molecules in both structures are associated via van der Waals interactions forming cavities occupied by solvent molecules (cyclosporin : tert-butyl methyl ether is 1 : 2).

scholarly journals Evaluation of dispersion type metal···π arene interaction in arylbismuth compounds – an experimental and theoretical study

2018 ◽  
Vol 14 ◽  
pp. 2125-2145 ◽  
Author(s):  
Ana-Maria Preda ◽  
Małgorzata Krasowska ◽  
Lydia Wrobel ◽  
Philipp Kitschke ◽  
Phil C Andrews ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Van Der Waals ◽  
Structural Features ◽  
Van Der Waals Interactions ◽  
Model Systems ◽  
Bismuth Atom ◽  
Dispersion Energy ◽  
Space Group ◽  
Intermolecular Contacts ◽  
London Dispersion

The dispersion type Bi···π arene interaction is one of the important structural features in the assembly process of arylbismuth compounds. Several triarylbismuth compounds and polymorphs are discussed and compared based on the analysis of single crystal X-ray diffraction data and computational studies. First, the crystal structures of polymorphs of Ph3Bi (1) are described emphasizing on the description of London dispersion type bismuth···π arene interactions and other van der Waals interactions in the solid state and the effect of it on polymorphism. For comparison we have chosen the substituted arylbismuth compounds (C6H4-CH═CH2-4)3Bi (2), (C6H4-OMe-4)3Bi (3), (C6H3-t-Bu2-3,5)3Bi (4) and (C6H3-t-Bu2-3,5)2BiCl (5). The structural analyses revealed that only two of them show London dispersion type bismuth···π arene interactions. One of them is the styryl derivative 2, for which two polymorphs were isolated. Polymorph 2a crystallizes in the orthorhombic space group P212121, while polymorph 2b exhibits the monoclinic space group P21/c. The general structure of 2a is similar to the monoclinic C2/c modification of Ph3Bi (1a), which leads to the formation of zig-zag Bi–arenecentroid ribbons formed as a result of bismuth···π arene interactions and π···π intermolecular contacts. In the crystal structures of the polymorph 2b as well as for 4 bismuth···π arene interactions are not observed, but both compounds revealed C–HPh···π intermolecular contacts, as likewise observed in all of the three described polymorphs of Ph3Bi. For compound 3 intermolecular contacts as a result of coordination of the methoxy group to neighboring bismuth atoms are observed overruling Bi···π arene contacts. Compound 5 shows a combination of donor acceptor Bi···Cl and Bi···π arene interactions, resulting in an intermolecular pincer-type coordination at the bismuth atom. A detailed analysis of three polymorphs of Ph3Bi (1), which were chosen as model systems, at the DFT-D level of theory supported by DLPNO-CCSD(T) calculations reveals how van der Waals interactions between different structural features balance in order to stabilize molecular arrangements present in the crystal structure. Furthermore, the computational results allow to group this class of compounds into the range of heavy main group element compounds which have been characterized as dispersion energy donors in previous work.

scholarly journals Crystal structures of [(N,N-dimethylamino)methyl]ferrocene and (R p,R p)-bis{2-[(dimethylamino)methyl]ferrocenyl}dimethylsilane

2020 ◽  
Vol 76 (9) ◽  
pp. 1437-1441
Author(s):  
Anna Krupp ◽  
Jessica Wegge ◽  
Felix Otte ◽  
Johannes Kleinheider ◽  
Helene Wall ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Surface Analysis ◽  
Intermolecular Interactions ◽  
Title Compound ◽  
Substitution Reaction ◽  
Van Der Waals ◽  
Hirshfeld Surface ◽  
Van Der Waals Interactions ◽  
Hirshfeld Surface Analysis ◽  
Lithium Compound

The title compound [(N,N-dimethylamino)methyl]ferrocene, [Fe(C5H5)(C8H12N)], (1), is an interesting starting material for the synthesis of planar chiral 1,2-disubstituted ferrocenes, as demonstrated by the preparation of (R p,R p)-bis{2-[(dimethylamino)methyl]ferrocenyl}dimethylsilane, [Fe2(C5H5)2(C18H18N2Si)], (2), from the lithiated derivative of 1. The configuration of the lithium compound is unchanged after the substitution reaction and the chirality is preserved in space group P212121. In both compounds, the Cp rings adopt eclipsed conformations. Hirshfeld surface analysis was used to investigate the intermolecular interactions, and showed that H...H (van der Waals) interactions dominate in both structures with contact percentages of 83.9 and 88.4% for 1 and 2, respectively.

Solid-state supramolecular architecture of carbenoxolone – comparative studies with glycyrrhetinic and glycyrrhizic acids

2015 ◽  
Vol 71 (1) ◽  
pp. 25-33 ◽  
Author(s):  
Ewa Tykarska ◽  
Maria Gdaniec
Keyword(s):  
Crystal Structures ◽  
Free Acid ◽  
Glycyrrhetinic Acid ◽  
Van Der Waals Interactions ◽  
Supramolecular Architecture ◽  
Crystal Forms ◽  
X Ray Crystallography ◽  
Carboxylate Groups ◽  
Solvent Molecules ◽  
The Impact

Carbenoxolone (CBXH2), a pharmaceutically relevant derivative of glycyrrhetinic acid, was studied by X-ray crystallography. The crystal structures of its unsolvated form, propionic acid and dimethoxyethane solvates and a solvated cocrystal of the free acid with its monobasic sodium salt CBXH2·CBXHNa·(butan-2-one)2·2H2O reveal that the recurring motif of supramolecular architecture in all crystal forms is a one-dimensional ribbon with closely packed triterpene fragments. It does not result from strong specific interactions but solely from van der Waals interactions. The ribbons are further arranged into diverse layer-type aggregates with a hydrophobic interior (triterpene skeletons) and hydrophilic surfaces covered with carboxylic/carboxylate groups. Solvent molecules included at the interface between the layers influence hydrogen-bonding interactions between the carbenoxolone molecules and organization of the ribbons within the layer. Comparison of crystal structures of carbenoxolone, glycyrrhizic acid and its aglycone–glycyrrhetinic acid have shown the impact of the size and hydrophilic character of the substituent at the triterpene C3 atom on the supramolecular architecture of these three closely related molecules.

Effect of Solventsand Temperature on O—H stretching Band of Methanol: Measure of van der Waals Interactions

1984 ◽  
Vol 39 (9) ◽  
pp. 888-892
Author(s):  
W. A. P. Luck ◽  
H. Y. Zheng
Keyword(s):  
Frequency Shift ◽  
Van Der Waals ◽  
Van Der Waals Interactions ◽  
Binary Solvent ◽  
Solvent Mixtures ◽  
Frequency Shifts ◽  
Oh Groups ◽  
Nonpolar Solvents ◽  
Different Temperatures ◽  
Solvent Molecules

The frequency shift of methanolic OH stretching bands by different nonpolar solvents at different temperatures can be described quantitatively by an equation proposed recently relating it to the temperature dependence of van der Waals interactions. The method shows that methanolic OH groups are surrounded by about 40% more solvent molecules than t-butanol OH groups. Frequency shifts of CH3OH by binary solvent mixtures demonstrate an averaged potential with small preference of the solvent with higher interaction.

Van der Waals interactions of the disulfide bond revealed: A microwave spectroscopic study of the diethyl disulfide–argon complex

2021 ◽  
Vol 154 (12) ◽  
pp. 124306
Author(s):  
Tao Lu ◽  
Daniel A. Obenchain ◽  
Jiaqi Zhang ◽  
Jens-Uwe Grabow ◽  
Gang Feng
Keyword(s):  
Spectroscopic Study ◽  
Disulfide Bond ◽  
Van Der Waals ◽  
Van Der Waals Interactions

scholarly journals Microscopic evidence of strong interactions between chemical vapor deposited 2D MoS2 film and SiO2 growth template

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Woonbae Sohn ◽  
Ki Chang Kwon ◽  
Jun Min Suh ◽  
Tae Hyung Lee ◽  
Kwang Chul Roh ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Spherical Aberration ◽  
Van Der Waals ◽  
Chemical Vapor ◽  
Interface Layer ◽  
Van Der Waals Interactions ◽  
Strong Interactions ◽  
Transition Electron Microscopy ◽  
Oxide Substrates

AbstractTwo-dimensional MoS2 film can grow on oxide substrates including Al2O3 and SiO2. However, it cannot grow usually on non-oxide substrates such as a bare Si wafer using chemical vapor deposition. To address this issue, we prepared as-synthesized and transferred MoS2 (AS-MoS2 and TR-MoS2) films on SiO2/Si substrates and studied the effect of the SiO2 layer on the atomic and electronic structure of the MoS2 films using spherical aberration-corrected scanning transition electron microscopy (STEM) and electron energy loss spectroscopy (EELS). The interlayer distance between MoS2 layers film showed a change at the AS-MoS2/SiO2 interface, which is attributed to the formation of S–O chemical bonding at the interface, whereas the TR-MoS2/SiO2 interface showed only van der Waals interactions. Through STEM and EELS studies, we confirmed that there exists a bonding state in addition to the van der Waals force, which is the dominant interaction between MoS2 and SiO2. The formation of S–O bonding at the AS-MoS2/SiO2 interface layer suggests that the sulfur atoms at the termination layer in the MoS2 films are bonded to the oxygen atoms of the SiO2 layer during chemical vapor deposition. Our results indicate that the S–O bonding feature promotes the growth of MoS2 thin films on oxide growth templates.

Concisely modularized assembling of graphene-based thin films with promising electrode performance

2019 ◽  
Vol 3 (7) ◽  
pp. 1462-1470 ◽  
Author(s):  
Weiwei Wei ◽  
Rohit L. Vekariy ◽  
Chuanting You ◽  
Yafei He ◽  
Ping Liu ◽  
...  
Keyword(s):  
Thin Films ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Double Layer ◽  
Van Der Waals ◽  
Cellulose Nanofibers ◽  
Van Der Waals Interactions ◽  
Electrode Performance ◽  
Reduced Graphene

Highly dense thin films assembled from cellulose nanofibers and reduced graphene oxide via van der Waals interactions to realize ultrahigh volumetric double-layer capacitances.

A comparison between approaches for the calculation of van der Waals interactions in flotation systems

2021 ◽  
Vol 167 ◽  
pp. 106804
Author(s):  
C. Weber ◽  
P. Knüpfer ◽  
M. Buchmann ◽  
M. Rudolph ◽  
U.A. Peuker
Keyword(s):  
Van Der Waals ◽  
Van Der Waals Interactions
Sign in / Sign up

Export Citation Format

Share Document