Single Guest Research Articles

Supramolecular Catalyzed Cascade Reduction of Azaarenes Interrogated via Data Science.

Catalysis of multicomponent transformations requires controlled assembly of reactants within the active site. Supramolecular scaffolds possess synthetic microenvironments that enable precise modulation over noncovalent interactions (NCIs) engaged by reactive, encapsulated species. While molecular properties that describe the behavior of single guests in host cavities have been studied extensively, multicomponent transformations remain challenging to design and deploy. Here, simple univariate regression and threshold analyses are employed to model reactivity in a cascade reduction of azaarenes catalyzed by water-soluble metal organic cages. Yield and stereoselectivity models help deduce unknown mechanisms of reactivity by the multicomponent, host-guest complexes. Furthermore, a comprehensive model is established for NCIs driving stereoselectivity in the reported host-guest adducts.

Imaging of Single Molecular Behaviors Under Bifurcated Three-Centered Hydrogen Bonding.

The mechanism for interaction and bonding of single guest molecules with active sites fundamentally determines the sorption and subsequent catalytic processes occurring in host zeolitic frameworks. However, no real-space studies on these significant issues have been reported thus far, since atomically visualizing guest molecules and recognizing single Al T-sites in zeolites remain challenging. Here, we atomically resolved single thiophene probes interacting with acid T-sites in the ZSM-5 framework to study the bonding behaviors between them. The synergy of bifurcated three-centered hydrogen bonds and van der Waals interactions can "freeze" the near-horizontal thiophene and make it stable enough to be imaged. By combining the imaging results with simulations, direct atomic observations enabled us to precisely locate the single Al T-sites in individual straight channels. Then, we statistically found that the thiophene bonding probability of the T11 site is 15 times higher than that of the T6 site. For different acid T-sites, the variation in the interaction synergy changes the inner angle of the host-guest O-H···S hydrogen bond, thereby affecting the stability of the near-horizontal thiophene and leading to considerable bonding inhomogeneities.

Imaging of Single Molecular Behaviors Under Bifurcated Three‐Centered Hydrogen Bonding

AbstractThe mechanism for interaction and bonding of single guest molecules with active sites fundamentally determines the sorption and subsequent catalytic processes occurring in host zeolitic frameworks. However, no real‐space studies on these significant issues have been reported thus far, since atomically visualizing guest molecules and recognizing single Al T‐sites in zeolites remain challenging. Here, we atomically resolved single thiophene probes interacting with acid T‐sites in the ZSM‐5 framework to study the bonding behaviors between them. The synergy of bifurcated three‐centered hydrogen bonds and van der Waals interactions can “freeze” the near‐horizontal thiophene and make it stable enough to be imaged. By combining the imaging results with simulations, direct atomic observations enabled us to precisely locate the single Al T‐sites in individual straight channels. Then, we statistically found that the thiophene bonding probability of the T11 site is 15 times higher than that of the T6 site. For different acid T‐sites, the variation in the interaction synergy changes the inner angle of the host–guest O−H⋅⋅⋅S hydrogen bond, thereby affecting the stability of the near‐horizontal thiophene and leading to considerable bonding inhomogeneities.

Enhancing the kinetics of vanadium oxides via conducting polymer and metal ions co-intercalation for high-performance aqueous zinc-ions batteries

Aqueous zinc-ions batteries with low cost, reliable safety, high theoretical specific capacity and eco-friendliness have captured conspicuous attention in large-scale energy storage. However, the developed cathodes often suffer from low electrical conductivity and sluggish Zn2+ diffusion kinetics, which severely hampers the development of aqueous zinc-ions batteries. Herein, we successfully prepare Mg/PANI/V2O5•nH2O (MPVO) nanosheets through conducting polymers (polyaniline) and metal ions (Mg2+) co-intercalated strategy and systematically explore its electrochemical performance as cathode materials for aqueous zinc-ion batteries. Benefitting from the synergistic effect of polyaniline and Mg2+ co-intercalated, the MPVO exhibits larger interlayer spacing and higher electrical conductivity than the single guest intercalation, which significantly enhances the electrochemical kinetics. As a consequence, the MPVO cathodes deliver superior specific capacity, rate capability and long-term cycling performance. Moreover, multiple characterizations and theoretical calculations are executed to expound the relevant mechanism.Therefore, this work provides a novel thought for the design of high-performance cathode materials for aqueous ZIBs.

Phase equilibria of hydrates from ternary mixtures of methane + ethane + propane and methane + propane + carbon dioxide

AbstractHydrate–liquid–vapour (HLV) equilibrium of aqueous clathrates formed from gas mixtures can be complex compared to hydrates formed with single guests. Typically, pressure and temperature are controlled to obtain these data, but for multicomponent systems, it is necessary to control/report more intensive variables, namely, composition. Metastability, manifested as impractically long experimental times, has been reported to be a challenge with some multicomponent systems. We present HLV equilibrium conditions of two ternary gas mixtures: methane + ethane + propane (90:7:3 molar ratio) and methane + propane + carbon dioxide (55:5:40 molar ratio). Conditions varied in the temperature range of 275–285 K and the pressure range of 1.24–4.75 MPa. Experimental standard uncertainties were on average 0.10 K and 0.005 MPa for methane + ethane + propane and 0.19 K and 0.005 MPa for methane + propane + carbon dioxide. Our technique allowed us to bypass the limitations reported in the literature and provided fast, reproducible HLV equilibria for gas‐dominated systems.

John the Theologian and His Paschal Gospel: A Prologue to Theology by John Behr

Reviewed by: John the Theologian and His Paschal Gospel: A Prologue to Theology by John Behr Matthew Z. Vale John the Theologian and His Paschal Gospel: A Prologue to Theology by John Behr (Oxford: Oxford University Press, 2019), xv + 388 pp. Father Behr's book defies summary. Its ambitions span several fields—patristics, contemporary biblical scholarship, speculative systematics, phenomenology—and Behr has controversial proposals in each. The book is not (expressly) a work of systematic theology, but its speculative élan and its ambition to give a normative account of Christian theology's beating heart is unmistakable. If a vice of the book is vagueness on questions of burning Christological, protological, and eschatological interest, among its virtues is the verve and vividness with which it provokes such questions to begin with. Behr has written, not a book on John, but a Johannine manifesto on theology. [End Page 989] The book is a "symposium" in three parts, each inviting a different kind of reader of John's gospel. The first is predominantly "historical" (the early Fathers of the Johannine school, reconstructed by modern scholarship), the second predominantly "exegetical" (contemporary biblical studies), and the third "philosophical," with a single guest in Michel Henry. The book's heart is an argument about what "incarnation" means. When it comes to the Incarnation, we labor, Behr says, under what Quentin Skinner calls a "mythology of doctrine," the hermeneutical fallacy of projecting onto a tradition's classical writers positions and whole doctrinal categories developed only later (6–8). The mythology of doctrine Behr opposes is, in fact, a mythological notion of the Incarnation as "an episode in the biography of the Word" (a phrase from Rowan Williams), the episode when a "pre-incarnate Word" is born as Jesus (3, and throughout). To break the ice on this mythology, part 1 reconstructs an original milieu for John's Gospel—a school of John the Evangelist, centered upon an original Pascha celebration—in which "becoming flesh," "Word," and "human being" mean something other than the dogmatic meanings we project back onto them. This Johannine school is not the Johannine "community" posited by historical-critical studies, but the school of John's "hearers" that J. B. Lightfoot traced from Polycarp of Smyrna, Ignatius of Antioch, Papias of Hierapolis, and Melito of Sardis down to Irenaeus (30–31). Behr's reconstruction makes the following proposals. Our evangelist is John the Elder, the beloved disciple, not the Synoptics' son of Zebedee. This John was plausibly an eyewitness to the crucifixion—alone among the evangelists. He authored both the Gospel and the Apocalypse bearing his name, according to near unanimous second-century tradition (76). The Apocalypse was possibly written before the Gospel, perhaps before the Temple's destruction. John the Elder originated the yearly Pascha celebration, and it remained peculiar to his school until the second half of the second century. This feast originally celebrated the crucifixion, burial, resurrection, ascension, and Pentecost as the single event of the Passion, just as in John's Gospel Jesus's ascension (12:32), glorification (13:31–2), and "handing down the Spirit" (19:30) are identified with the crucifixion. Only later was the Passion's simple white light refracted into the liturgical cycle's rainbow of distinct feasts (91–92, 243). This reconstruction is explicitly speculative. Its purpose is to enliven our imaginations about what the evangelist's vision may possibly be. If the mythological picture of the Incarnation is easily recognized as false, our theological traditions still have not entirely exorcised it from their standard narration. Behr proposes a Johannine narration untroubled by this [End Page 990] mythology. The Incarnation is not a novelty occurring for God at some moment. No previously fleshless divine agent undergoes change to become flesh at some time. The Incarnation must instead be understood "apocalyptically," as the eternal mystery of Jesus Christ being revealed for us in time (256-57). The Incarnation is Jesus's eternal identity as the Word being revealed and wrought in time and pro nobis by the Passion (24, 29, 257, 130). John's Gospel should be read, in John Ashton's words, as "an apocalypse—in reverse, upside down, inside out" (4, 99...

Morphology and Interphase Boundary Behavior of Gas Hydrates of Single, Binary, and Ternary Guests

Morphology and Interphase Boundary Behavior of Gas Hydrates of Single, Binary, and Ternary Guests

Spatial distribution of single guest molecules along thickness of thin films of poly(2-hydroxyethyl acrylate).

We have investigated three-dimensional distribution and diffusion behaviors of single guest dyes in 1-µm thick films of poly(2-hydroxyethyl acrylate) (PHEA) by using astigmatism imaging method. Perylene diimide derivative (BP-PDI) in the PHEA films localized along the Z-axis at ca. Z = 600-700nm distant from the interface (Z = 0) between PHEA and glass substrate. This Z-localization was not observed in different polymer films of poly(methyl methacrylate) (PMMA), poly(methyl acrylate) (PMA), and polystyrene (PSt). Because the glass transition temperature of the PHEA is lower than the room temperature, BP-PDI in the PHEA films exhibited Brownian motion, normal diffusion on the XY plane and confined motion along the Z-direction. For elucidating the mechanism of the peculiar localization of the guest dyes along film thickness in the PHEA films, we measured diffusion behaviors of different dyes, R6G and Atto 488, in 1-µm thick PHEA films, obtaining result that the Z-distributions of the dyes were overall similar to that of BP-PDI. The result indicates that the Z-localization of the guest dyes should be ascribed not to the interaction between glass surface and guest dye but mainly to the Z-dependent property of the PHEA film. Indeed, the lateral diffusion coefficients of the guest dyes depended on their Z-positions.

Rotation in an Enantiospecific Self-Assembled Array of Molecular Raffle Wheels.

Tailored nano‐spaces can control enantioselective adsorption and molecular motion. We report on the spontaneous assembly of a dynamic system—a rigid kagome network with each pore occupied by a guest molecule—employing solely 2,6‐bis(1H‐pyrazol‐1‐yl)pyridine‐4‐carboxylic acid on Ag(111). The network cavity snugly hosts the chemically modified guest, bestows enantiomorphic adsorption and allows selective rotational motions. Temperature‐dependent scanning tunnelling microscopy studies revealed distinct anchoring orientations of the guest unit switching with a 0.95 eV thermal barrier. H‐bonding between the guest and the host transiently stabilises the rotating guest, as the flapper on a raffle wheel. Density functional theory investigations unravel the detailed molecular pirouette of the guest and how the energy landscape is determined by H‐bond formation and breakage. The origin of the guest's enantiodirected, dynamic anchoring lies in the specific interplay of the kagome network and the silver surface.

Experimental Measurement of Multiple Hydrate Structure Formation in Binary and Ternary Natural Gas Analogue Systems by Isochoric Equilibrium Methods

Traditionally, it is commonly assumed that a single gas hydrate (or clathrate hydrate) structure/phase is formed in natural gas systems—e.g., “s-II natural gas (NG) hydrates” or “s-I methane hydrates”—based on that which is understood to be the most thermodynamically stable at incipient phase boundary conditions. This applies with respect to both studies of hydrates in natural sediments, and in the case of hydrocarbon production operations, including the testing of low-dosage hydrate inhibitors (LDHIs). Here, we present the results of experimental studies of simple propane (C₃), binary methane–propane (C₁–C₃), and ternary methane–ethane–propane (C₁–C₂–C₃) hydrate systems, aimed at investigating phase behavior at higher subcoolings where significant water conversions to clathrates—and associated gas fractionation—might be expected to result in the formation of more than one hydrate structure. Measurements were made by means of established, reliable, isochoric equilibrium step-heating/cooling approaches. In the single guest propane system, pressure–temperature (PT) conditions follow the gas hydrate phase boundary, in agreement with the univariant hydrate + gas + water (H + G + W) equilibrium. By contrast, binary and ternary mixes clearly show PT behavior consistent with the growth of at least two and four hydrate phases, respectively, with these forming sequentially on cooling, and dissociating in the corresponding reverse order upon heating. In-house hydrate model (HydraFLASH) predictions support experimental observations, pointing to processes being gas fractionation driven; the mixed C₃–C₁ or C₃–C₂–C₁ s-II type hydrates formed first close to the phase boundary preferentially incorporating the most strongly clathrate cage (5¹²6⁴) stabilizing propane, making the remaining gas leaner. Once C₃ is largely consumed, trends agree with less stable C₂–C₁ structures (s-II followed by s-I) then growing (where ethane is present), with this, like C₃ uptake, making remaining free gas increasingly of almost pure C₁. This ultimately drives systems toward the final simple, single guest C₁ s-I clathrate formation as the well-established univariant phase boundary for this structure is reached. As observed phase behavior arises because of gas fractionation, it can be expected to occur during hydrate formation in all mixed gas systems of relatively fixed composition (at constant volume or pressure). The findings highlight that care should be taken in the application of isochoric methods to multicomponent gas systems, given the potential for numerous (rather than just one) clear changes in heating curve slopes as different hydrate structures form/dissociate. In addition, results show that extending equilibrium steps well into the hydrate region can reveal important information on clathrate phase behavior with potentially significant implications for issues such as gas production from hydrates in sediments, hydrate technologies for gas capture/separation/storage in the energy industry, and flow assurance in hydrocarbon production operations.

Thermodynamic phase equilibrium of single-guest hydrate and formation data of hydrate in presence of chemical additives: a review

The present work deals with a review of single-guest hydrate phase equilibrium data and also hydrate equilibrium in presence of chemical additives, which operate as inhibitors, promoters, or both together. In the recent years, a very limited number of data collections on hydrate equilibrium has been produced; moreover, these data have not been fully reported in these works, making further research necessary to obtain complete information. We provide a detailed collection of the equilibrium data of hydrate containing single guest as CH4, C2H6, C3H8, C4H10, CO2, N2, Xe, Ar and Kr and a brief review of las-scale reactors nowadays used for making research on gas hydrate. These two kinds of information, will be extremely helpful for researchers which are planning to realize a new experimental apparatus for studying gas hydrate. It is well known how, rather than process parameters (i.e. pressure, temperature, presence of a porous medium and its permeability and porosity, presence of impurities, and so on), also specifics of each reactor may strongly intervene on formation results. The second part of this work consists in a collection of the thermodynamic equilibrium data of hydrate in the presence of additives. Some substances are known to be selective inhibitors (promoters); other compounds have greater efficiency when coupled to further chemicals while, in some cases, such coupling can cancel the inhibitory (or promoter) effect. Finally, a state of the art of hydrate equilibrium experiments carried out with methane and carbon dioxide, with a simultaneous presence of inhibitors and promoters, was provided.

Guest Encapsulation within Surface-Adsorbed Self-Assembled Cages.

Coordination cages encapsulate a wide variety of guests in the solution state. This ability renders them useful for applications such as catalysis and the sequestration of precious materials. A simple and general method for the immobilization of coordination cages on alumina is reported. Cage loadings are quantified via adsorption isotherms and guest displacement assays demonstrate that the adsorbed cages retain the ability to encapsulate and separate guest and non-guest molecules. Finally, a system of two cages, adsorbed on to different regions of alumina, stabilizes and separates a pair of Diels-Alder reagents. The addition of a single competitive guest results in the controlled release of the reagents, thus triggering their reaction. This method of coordination cage immobilization on solid phases is envisaged to be applicable to the extensive library of reported cages, enabling new applications based upon selective solid-phase molecular encapsulation.

On the synergy of matrix-isolation infrared spectroscopy and vibrational configuration interaction computations

The key feature of matrix-isolation infrared (MI-IR) spectroscopy is the isolation of single guest molecules in a host system at cryogenic conditions. The matrix mostly hinders rotation of the guest molecule, providing access to pure vibrational features. Vibrational self-consistent field (VSCF) and configuration interaction computations (VCI) on ab initio multimode potential energy surfaces (PES) give rise to anharmonic vibrational spectra. In a single-sourced combination of these experimental and computational approaches, we have established an iterative spectroscopic characterization procedure. The present article reviews the scope of this procedure by highlighting the strengths and limitations based on the examples of water, carbon dioxide, methane, methanol, and fluoroethane. An assessment of setups for the construction of the multimode PES on the example of methanol demonstrates that CCSD(T)-F12 level of theory is preferable to compute (a) accurate vibrational frequencies and (b) equilibrium or vibrationally averaged structural parameters. Our procedure has allowed us to uniquely assign unknown or disputed bands and enabled us to clarify problematic spectral regions that are crowded with combination bands and overtones. Besides spectroscopic assignment, the excellent agreement between theory and experiment paves the way to tackle questions of rather fundamental nature as to whether or not matrix effects are systematic, and it shows the limits of conventional notations used by spectroscopists.

The nature of the Sulfur-Metallic bonds (Metal = Ni, Pd and Pt) in doped gold nanoclusters: A density functional approach

“Atomically precise gold nanoparticles” that constitute single guest atom doped gold cores besides being protected by ligands, have drawn much attention in the fields of biology, chemistry and physics. To investigate the foundation of organic-metallic interface, metallic alloy- H2S complexes are used to model the core-ligand interactions. In this work, simulation of platinum group doped gold dimers and triangular trimers bonded to H2S, are investigated. To simulate experimental results, features including bond lengths, vibrational frequencies and binding energies were calculated for the dimers of platinum group metals and gold, via DFT. The Au-M dimers have minimum magnetic dipole moments compared to the dimers of two platinum group metals. Among the three platinum group atoms simulated, the relativistic effect prevents Pd from being tightly bonded to other metallic atoms. The “donor-acceptor” model is put forward for the complexes of H2S molecules and dimer/trimers, to explain the interaction of sulfur-metal bonds. The possibility of neighboring metallic atoms affecting the acceptor, Au or platinum group metallic atoms is distinct. A neighboring acceptor may improve the S-M interaction such as S-Ni bond while a neighboring weak donor may reduce the S-M interactions such as S-Pd/Pt bonds. With the isosurface plot of densities of electrons/holes at binding, one can identify that such an interaction involves both electrostatic and covalent features. The complexes having H2S as ligand and cores of the real gold clusters verified the reliability of the donor-acceptor model qualitatively.

Energetically significant anti-parallel π-stacking and unconventional anion-π interactions in phenanthroline based Ni(II) and Cu(II) coordination compounds: Antiproliferative evaluation and theoretical studies

Two new coordination compounds of Ni(II) and Cu(II), viz. [Ni(phen)2Cl(H2O)] 4-NO2bz·3H2O (1) and [Cu(phen)2Cl]Cl·5H2O (2) (phen = 1,10-phenanthroline, 4-NO2bz = 4-nitrobenzoate) have been synthesized and characterized by single crystal X-ray diffraction, elemental analysis, FT-IR, electronic spectroscopy, TGA and EPR. The detailed crystal structure analysis of the Werner Type Clathrate 1 reveals the self-assembled unconventional enclathration of 4-NO2bz moieties in supramolecular Ni(II) hosts. In addition to the conventional discrete (H2O)n clusters in the crystal structure of 2, the layered architecture involves enclathration of single guest water molecules in the Cu(II) supramolecular hosts. We have theoretically analysed the biologically relevant anti-parallel π-stacking interactions in compound 1 and two types of anion–π interactions involving coordinated and uncoordinated chloride ions in compound 2. MEP surface analysis and DFT calculations reveal that the anti-parallel π-stacking interaction in 1 is energetically significant and enhanced upon complexation of the ligands to the Ni(II) centre. Remarkably, studies also reveal that in addition to the conventional anion⋯π interaction involving the chloride anion in the lattice, the unusual Cl(chlorido)⋯π interaction observed in the crystal assembly of 2 is also energetically significant. The antiproliferative potential of the compounds 1 and 2 have been studied in Dalton’s Lymphoma (DL) malignant cancer cell lines considering MTT cell viability and apoptosis assays. The compounds 1 and 2 exhibited significant concentration dependent increase in cell cytotoxicity and apoptosis in DL cells with negligible cytotoxicity in normal (PBMC) cells.

Structural and vibrational properties of agrellite

Agrellite, NaCa2Si4O10F, is a tubular silicate mineral which crystal structure is characterized by extended [Si8O20]8– tubes and has a two-dimensional channel system. The mineral is a representative of a complex silicate family which contains some structural voids but cannot be considered as microporous because of small channel widths. However, the channel system of such minerals is able to host single guest atoms, molecules or radicals which can affect their physical properties. Presently, the exact mechanism of such hosting is undetermined. However, such information could be quite useful for materials’ application as zeolites as well as for a better understanding of their formation mechanisms. In this work we couple X-ray diffraction, infrared (IR) spectroscopy and ab initio calculations to identify structural features in agrellite from Malyy Murun massif (Russia) caused by incorporation of either H2O or OH− into the channel system. We construct structural models of water-containing NaCa2Si4O10F and identified H2O positions. The derivation of H2O sites is based on simulation of IR-spectra. Infrared spectroscopy in combination with the ab initio calculation has proven to be an effective tool for the identification of the structural positions of hydroxyl anions (OH−) and neutral water groups (H2O) in minerals.

Enhanced Characterization of Pyrene Binding in Mixed Cyclodextrin Systems via Fluorescence Spectroscopy.

Although significant effort has been expended to analyze the binding of pyrene in β-cyclodextrin and γ-cyclodextrin, little has been published on the binding of this guest in β-cyclodextrin derivatives (methyl-β-cyclodextrin and 2-hydroxypropyl-β-cyclodextrin) or in mixtures of such derivatives, despite the fact that these derivatives are known to have different supramolecular properties that facilitate unique modes of complexation. Reported herein is a detailed spectroscopic investigation of the binding of pyrene in β-cyclodextrin derivatives and in binary mixtures of cyclodextrins. Py values, defined as the ratio of representative vibronic bands in the fluorescence emission of pyrene, were used to measure changes in the pyrene microenvironment in the presence of the cyclodextrin hosts, and indicated that unmodified β-cyclodextrin is unique in providing a fully hydrophobic environment for pyrene through the use of two cyclodextrins to bind a single pyrene guest. By comparison, both γ-cyclodextrin and modified β-cyclodextrin analogues bind pyrene in a less hydrophobic environment through 1:1 binding stoichiometries that allow for continued interactions between the incompletely encapsulated pyrene guest and the aqueous solvent system. Binary mixtures of cyclodextrins were also explored and reinforce the unique properties of the unmodified β-cyclodextrin host. Graphical Abstract The unique binding geometries of pyrene in beta-cyclodextrin and its derivatives leads to measurable fluorescence emission signals, whose information can be used to elucidate the highly structurally dependent binding geometries and stoichiometries.

Modeling of Hydrate Dissociation Curves with a Modified Cubic-Plus-Association Equation of State

A modified cubic-plus-association equation of state (CPA EoS) has been presented in recent works that enforces the representation of the pure component critical point, is based on an extended Mathias–Copeman α function, and uses a volume shift to improve liquid densities. In this work, this same version of the CPA model is applied together with the hydrate van der Waals and Platteeuw model for the description of hydrate dissociation curves. The model is applied to the description of both single and mixed guest hydrates, the results being compared with the available experimental data, and the predictions obtained using the commercial hydrates model from the Multiflash software. This analysis shows that, for most cases, this approach is accurate, with results similar to those of Multiflash. The accuracy of the model for describing the three phase compositions in hydrate + liquid + gas systems is also discussed.

Host compounds (+)-(2R,3R)-1,1,4,4-tetraphenylbutane-1,2,3,4-tetraol (TETROL) and (2R,3R)-(−)-2,3-dimethoxy-1,1,4,4-tetraphenylbutane-1,4-diol (DMT) with guests o-, m- and p- toluidine: A comparative investigation

In this work, we have compared the host abilities of closely related compounds (+)-(2R,3R)-1,1,4,4-tetraphenylbutane-1,2,3,4-tetraol (TETROL) and (2R,3R)-(−)-2,3-dimethoxy-1,1,4,4-tetraphenylbutane-1,4-diol (DMT) when these were recrystallized from single and mixed toluidine guests. Significant differences in host behaviour and selectivities were revealed and these were explained by means of single crystal diffraction experiments. Thermal analyses were used to determine the relative complex stabilities, and these data correlated exactly with the host selectivity orders for both TETROL and DMT.

Prediction of vapor-liquid-hydrate equilibrium conditions for single and mixed guest hydrates with the SAFT-VR Mie EOS

Abstract In this work, a thermodynamic modeling approach is utilized to predict the formation conditions of natural gas hydrates. Our approach uses van der Waals-Platteeuw (vdWP) model for the hydrate phase and the SAFT-VR Mie equation of state (EOS) for the vapor and liquid phases. We employ three different association schemes into the SAFT-VR Mie EOS to account for hydrogen bonds among water molecules using square-well (SW), Lennard-Jones (LJ) and Mie potentials. The SAFT-VR Mie EOS is used to determine the solubility of hydrate formers in liquid water. We study single and mixed guest hydrates and compare the results with experimental data. The comparisons with experimental data show that our model gives excellent to satisfactory predictions of the dissociation pressures for single and mixed guest hydrates without re-adjustment of the Langmuir constants.