The Motion of Guest Molecules in Clathrate Hydrates

1971 ◽  
Vol 49 (8) ◽  
pp. 1224-1242 ◽  
Author(s):  
D. W. Davidson
Keyword(s):  
Low Temperatures ◽  
Wide Distribution ◽  
Water Molecules ◽  
Energy Calculation ◽  
Guest Molecules ◽  
Jones Potential ◽  
Dielectric Absorption ◽  
Electrostatic Fields ◽  
Cl Atoms ◽  
Range Of Variation

The reorientation of molecules encaged in hydrates of structures I and II is controlled mainly by the cage geometry and the electrostatic fields of the water molecules. Departure from spherical symmetry of the short-range interactions between the guest molecule and the water molecules which form the cages leads to preferred orientations which become increasingly occupied at low temperatures. A modified Lennard-Jones potential energy calculation shows the preferred positions of Cl2 to lie off-center and close to the equatorial plane of the tetrakaidecahedral cage with the Cl atoms near the axial planes of symmetry. In an attempt to account for the remarkable reorientational freedom of polar guest molecules, the electrostatic fields of the water molecules are treated in detail. It is shown that the geometry of the cages causes the sum of the fields of the cage water dipoles to almost vanish at points near the cage center, but that this is not true of the resultant quadrupolar fields. It is suggested that the quadrupolar fields are also relatively small because the hydrogen bonding to four neighbors considerably reduces the quadrupole moment of the water molecule. The orientational disorder of the water molecules results in a wide distribution of resultant electrostatic fields in different cages. This appears to be the origin of the great width of the dielectric absorption observed at low temperatures in tetrahydrofuran hydrate and of the wide temperature range of variation of the proton magnetic resonance (p.m.r.) line width in tetrahydrofuran deuterate.

1,4-Dioxane Hydrate: Dielectric Absorption by a Nondipolar Enclathrated Molecule

1975 ◽  
Vol 53 (15) ◽  
pp. 2217-2222 ◽  
Author(s):  
S. R. Gough ◽  
J. A. Ripmeester ◽  
D. W. Davidson
Keyword(s):  
Continuous Wave ◽  
Effective Activation Energy ◽  
Water Molecules ◽  
Effective Activation ◽  
Large Structure ◽  
Total Dipole Moment ◽  
Guest Molecules ◽  
X Ray ◽  
Dielectric Absorption ◽  
Relaxation Studies

X-Ray, continuous-wave and pulsed n.m.r., and dielectric relaxation studies show the hydrate of 1,4-dioxane (D) to be a normal clathrate hydrate of von Stackelberg's structure II with composition D·∼17H2O. The reorientation rate of the relatively large D molecule is slower and the effective activation energy(l.6 kcal/mol) larger than for other guest molecules previously studied in hydrates of the same structure. Weak dielectric absorption associated with reorientation of nondipolar D molecules is attributed mainly to the induction of a total dipole moment of ∼0.2 D in the 28 water molecules of the large structure II cage by two equal and opposed dipoles in the chair form of D.

scholarly journals Bis[μ-1,3-bis(1H-imidazol-1-yl)propane-κ2N3:N3′]bis(dichloridozinc) dihydrate

2014 ◽  
Vol 70 (5) ◽  
pp. m184-m184
Author(s):  
Xiao-Juan Wang ◽  
Yun-Long Feng
Keyword(s):  
Zinc Complex ◽  
Complex Molecule ◽  
Dimensional Structure ◽  
Water Molecules ◽  
Coordination Geometry ◽  
Tetrahedral Coordination ◽  
Lattice Water ◽  
Bridging Ligand ◽  
Cl Atoms ◽  
Distorted Tetrahedral Coordination

The title hydrated complex, [Zn2Cl4(C9H12N4)2]·2H2O, is a discrete dinuclear zinc complex with 1,3-bis(1H-imidazol-1-yl)propane as the bridging ligand. The complex molecule lies about a crystallographic inversion centre. The ZnIIatom exhibits a distorted tetrahedral coordination geometry defined by two imidazole N atoms and two Cl atoms. O—H...Cl hydrogen bonding between the lattice water molecules and the terminal Cl atoms of the molecule lead to a two-dimensional structure extending parallel to (100).

scholarly journals Supramolecular Complexes of Cucurbiturils with Second Group Metal Salts and Hydrates and Histamine

INEOS OPEN ◽  
2021 ◽  
Vol 4 ◽  
Author(s):  
Yu. A. Borisov ◽  
◽  
S. S. Kiselev ◽  
Keyword(s):  
Aqueous Solution ◽  
Density Functional Theory ◽  
Density Functional ◽  
Metal Salts ◽  
Supramolecular Complexes ◽  
Water Molecules ◽  
Functional Theory ◽  
Guest Molecules ◽  
First Time ◽  
Formation Energies

The interaction of cucurbiturils (Q6, Q7, and Q8) with Ca and Ba chlorides and iodides are studied for the first time by density functional theory. The thermodynamic parameters for the formation of host–guest complexes are calculated. The structures of complexes of Q6 and Q7 with one and two guest molecules are established. The energy parameters for the transfer of Be2+ and Ba2+ cations from an aqueous solution into the cavity of Q7 containing n water molecules are defined. The dependences of the formation energies for complexes Q7WnBe2+ and Q7WnBa2+ on the number of water molecules are shown to be parabolic, with the energy minima at n = 5 and n = 6, respectively. It is found that Q7 can form in an aqueous solution supramolecular complexes with protonated histamine (HA) and neutral histamine in the presence of Ca2+ ions.

scholarly journals Crystal structure of aquatris{μ-N-[bis(diethylamino)phosphoryl]-2,2,2-trichloroacetamidato-κ3O,O′:O}calciumsodium

2016 ◽  
Vol 72 (12) ◽  
pp. 1683-1686 ◽  
Author(s):  
Iuliia Shatrava ◽  
Kateryna Gubina ◽  
Vladimir Ovchynnikov ◽  
Viktoriya Dyakonenko ◽  
Vladimir Amirkhanov
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Water Molecules ◽  
Carbonyl Groups ◽  
Coordination Environment ◽  
Distorted Octahedral Coordination ◽  
Distorted Octahedral ◽  
Phosphoryl Groups ◽  
Cl Atoms ◽  
Distorted Octahedral Coordination Environment

In the molecular structure of the title compound, [CaNa(C10H20Cl3N3O2P)3(H2O)], the Ca2+ion has a slightly distorted octahedral coordination environment defined by six O atoms which belong to the carbonyl and phosphoryl groups of the three coordinating ligands. Two Cl atoms of CCl3groups and four O atoms form the coordination environment of the Na+ion: three from the carbonyl groups of ligands and one O atom from a coordinating water molecule. In the crystal, the bimetallic complexes are assembled into chains along thec-axis directionviaO—H...O hydrogen bonds that involve the coordinating water molecules and the phosphoryl groups.

scholarly journals Phase transformations in cucurbituril host-guest complexes

2014 ◽  
Vol 70 (a1) ◽  
pp. C646-C646
Author(s):  
Oksana Danylyuk ◽  
Karolina Kedra-Krolik ◽  
Marta Worzakowska ◽  
Joanna Osypiuk-Tomasik ◽  
Vladimir Fedin
Keyword(s):  
Single Crystal ◽  
Crystal Lattice ◽  
Supramolecular Assembly ◽  
Water Molecules ◽  
Guest Molecules ◽  
X Ray ◽  
Host Guest Complex ◽  
Crystallographic Study ◽  
Partial Dehydration ◽  
Structure Changes

The retention of crystallinity upon desolvation of molecular crystals is not common, as the molecules are rigidly and densely packed in the crystals and the original framework usually collapses once solvent is removed from the structure. However, in rare cases the host framework remains substantially unaffected by solvent (guest) removal yielding structure with open channels or discrete lattice voids that can show permanent porosity. [1] Furthermore, sometimes happens, the desolvation process proceeds as single-crystal to single-crystal transformation resulting in distortion and sliding of the structure, changes in conformation, coordination modes and/or space group. Here we would like to present crystallographic study and thermal analysis on the dehydration process of the crystalline supramolecular complex between macrocyclic host cucurbit[6]uril and dopamine. In the solid state the 1:1 host-guest complex assembles into hexameric tubes with water-filled interior channels. Another set of water channels is created between three neighboring tubes in the crystal lattice. The crystals of such supramolecular assembly are not stable when out from mother solution and immediately start to loose water upon exposure to air. However, despite severe cracking the crystals dried in air maintained their integrity and still gave satisfactory diffraction pattern. The X-ray analysis showed significant decrease in the unit cell volume of the partially dehydrated crystals that corresponds to the liberation of some of the water molecules from the channels. Moreover, the reorganization of dopamine guest molecules has occurred in the crystal lattice as a response to the escape of water molecules from the structure. The partial dehydration and reorganization of the supramolecular framework proceeds via a single-crystal to single-crystal mechanism.

2,2′-[m-Phenylenebis(methyleneimino)]dipyridinium dichloridobis(4-formylbenzoato-κ2 O,O′)cadmate(II) dihydrate

2007 ◽  
Vol 63 (11) ◽  
pp. m2834-m2834
Author(s):  
Zhao-Peng Deng ◽  
Shan Gao ◽  
Li-Hua Huo ◽  
Hui Zhao
Keyword(s):  
Rotation Axis ◽  
Chain Structure ◽  
Octahedral Geometry ◽  
Water Molecules ◽  
Carboxylate Group ◽  
Cl Atoms ◽  
Hydrogen Bonded

The CdII atom in the title salt, (C18H20N4)[CdCl2(C8H5O3)2]·2H2O, lies on a twofold rotation axis. It is chelated by the carboxylate group and exists in an octahedral geometry, with the Cl atoms cis to each other. The dication also lies on a twofold rotation axis. The cation and anion interact through one of the uncoordinated water molecules, forming a hydrogen-bonded chain structure that runs along the a axis.

Surface Properties and Gas Adsorption

2003 ◽  
Author(s):  
Toshiaki Enoki ◽  
Morinobu Endo ◽  
Masatsugu Suzuki
Keyword(s):  
Alkali Metal ◽  
Activated Charcoal ◽  
Low Temperatures ◽  
Gas Adsorption ◽  
Hydrogen Adsorption ◽  
Hydrogen Chemisorption ◽  
Guest Molecules ◽  
Hydrogen Molecules ◽  
General Aspects ◽  
Stage 1

It is well known that alkali metal binary GICs adsorb gaseous species (H2, N2, Ar, CH4, etc.) physisorptively at low temperatures, where physisorbed gaseous molecules are accommodated in the interstitials of the alkali metal lattice within the graphitic galleries (Lagrange and Hérold, 1975; Lagrange et al., 1972, 1976; Watanabe et al., 1971, 1972, 1973). The capacity for hydrogen adsorption, which is estimated at 144 cm3/g in KC24, for example, is large and comparable to the capacity in other adsorbers such as zeolite or activated charcoal. Interestingly, the physisorption phenomenon in alkali metal GICs has different features from that in conventional adsorbents such as zeolite or activated charcoal; that is, guest molecules in alkali metal GICs are not simply bonded to the adsorbents through weak van der Waals forces without any change in the electronic structures. Here we discuss the gas physisorption phenomenon in alkali metal GICs from general aspects, in relation to their specific features. Then in subsequent sections, we will give details of actual cases. Hydrogen is a typical gaseous molecule adsorbed in alkali metal GICs. Hydrogen physisorption takes place at low temperatures below about 200 K, where hydrogen molecules are accommodated in the graphitic galleries and are not dissociated into atomic hydrogen species. When the temperature is increased to over 200 K, the alkali metal GICs work as catalysts to hydrogen, resulting in the occurrence of hydrogen chemisorption. Hydrogen physisorption will be discussed in Section 8.1.2, hydrogen chemisorption and related issues have been discussed partly in Sections 2.2.1 and 5.4.1 from the viewpoints of structure and electronic properties, and will be discussed again in Section 8.1.2. Figure 8.1 represents the composition dependence of the amount of physisorption of hydrogen molecules in KCm at 77 K (Lagrange and Hérold, 1975). The composition of 1/m = 1/8 corresponds to the stage-1 compound and the composition 1/m = 1/24 to the stage-2 compound; intermediate compositions between 1/8 and 1/24 are considered to have a mixed structure of stage-1 and stage-2 compounds. The stage-1 compound does not adsorb hydrogen at all.

ChemInform Abstract: Complexes of Macrocyclic Polyethers and Neutral Guest Molecules: A Systematic Approach to the Complexation of Water Molecules by 2,6-Pyridinium Crown Ethers.

1986 ◽  
Vol 17 (25) ◽  
Author(s):  
P. D. J. GROOTENHUIS ◽  
J. W. H. M. UITERWIJK ◽  
D. N. REINHOUDT ◽  
C. J. VAN STAVEREN ◽  
E. J. R. SUDHOELTER ◽  
...  
Keyword(s):  
Crown Ethers ◽  
Systematic Approach ◽  
Water Molecules ◽  
Macrocyclic Polyethers ◽  
Guest Molecules

Modulated Phases in Amphiphilic Monolayers at the Water/Air Interface

1989 ◽  
Vol 177 ◽  
Author(s):  
David Andelman
Keyword(s):  
Fatty Acids ◽  
Free Energy ◽  
Low Temperatures ◽  
Theoretical Explanation ◽  
Free Energy Calculation ◽  
Energy Calculation ◽  
Dipolar Interactions ◽  
Hexagonal Symmetry ◽  
Modulated Phases ◽  
Air Interface

ABSTRACTRecently, modulated phases of insoluble monolayers of fatty acids and phospholipids spread on the water/air interface have been observed by fluorescence microscopy experiments. We propose a theoretical explanation of this observation by including electrostatic (dipolar) interactions in the total free energy calculation for the monolayer. Dipoles can originate from two sources: neutral amphiphiles have a permanent dipole and charged amphiphiles have an induced one. Modulated phases are found to be stable in two different limits: close to the liquid-gas transition and at low temperatures. Several phases with stripe and hexagonal symmetry are predicted and the phase transitions between them are calculated.

scholarly journals Crystal structure of a new hybrid antimony–halide-based compound for possible non-linear optical applications

2015 ◽  
Vol 71 (5) ◽  
pp. 498-501 ◽  
Author(s):  
Tarek Ben Rhaiem ◽  
Habib Boughzala
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Water Molecules ◽  
Inorganic Layer ◽  
Organic Part ◽  
Organic Layers ◽  
Hydrogen Bonding Interactions ◽  
Optical Applications ◽  
Cl Atoms ◽  
Inorganic Layers

The hybrid title compound,catena-poly[[[bis(1,4-diazoniabicyclo[2.2.2]octane) [tetraachloridoantimonate(III)]-μ-chlorido-[tetrachloridoantimonate(III)]-μ-chlorido]] monohydrate], {(C6H14N2)2[Sb2Cl10]·H2O}n, is self-assembled into alternating organic and inorganic layers parallel to thebcplane. The anionic inorganic layer consists of infinite zigzag chains of corner-sharing [SbCl6]3−octahedra running along thebaxis. The organic part is made up of 1,4-diazoniabicyclo[2.2.2]octane dications (dabcoH22+). The water molecules in the structure connect inorganic and organic layers. Hydrogen-bonding interactions between the ammonium groups, water molecules and Cl atoms ensure the structure cohesion.

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