Toluene Molecules Research Articles

Molecular dynamics simulation of poly-m-phenylene isophthalamide polymer membrane modified by UiO-66 (NH2) MOF for separation of toluene/methanol mixture

Pervaporation is the purification technology which utilizes the transport properties of polymer membranes and has several important properties: energy efficiency, environmental friendliness, and a high degree of purification. To improve the transport properties, polymer membranes are modified with special nanoparticles. In this work we study the translational mobility of methanol and toluene molecules inside a poly-m-phenylene isophthalamide membrane with and without the nanoparticle of UiO-66 (NH2) metal-organic framework (UiO-66 (NH2) MOF) using full atomistic molecular dynamics simulation with microsecond trajectories. It was found that methanol has a high translational mobility inside the polymer matrix. Moreover, this mobility is significantly increased by addition of UiO-66 (NH2) MOF. Toluene molecules are practically immobile inside the polymer matrix and tend to form clusters with each other. Due to the inclusion of a nanoparticle, toluene molecules “get stuck” inside UiO-66 (NH2) MOF and its surface. We believe that the obtained results will contribute to the purposeful development and study of polymer matrices for the pervaporation process.

Porous, Tremella-like NiFe2O4 with Ultrathin Nanosheets for ppb-Level Toluene Detection

As a typical spinel ferrite, NiFe2O4 is suitable for use in gas sensors. Herein, we report the fabrication of porous, tremella-like NiFe2O4 assembled using porous, ultrathin nanosheets via the coordination of Ni2+ and Fe2+ with 1,4-phenylenediboronic acid. The optical band gap of the NiFe2O4 is estimated to be about 1.7 eV. Furthermore, the NiFe2O4 sensor annealed at 400 °C exhibits a low detection limit of 50 ppb, a fast response/recovery time (11.6 s/41.9 s to 10 ppm toluene), good reproducibility, and long-term stability at 220 °C. The suitable sensing performances can be attributed to the good catalytic activity of NiFe2O4 to toluene oxidation. Moreover, the ultrathin nanosheets with porous structures provide a large number of active sites to significantly favor the diffusion and adsorption/desorption of toluene molecules. This current work provides an insight into fabricating NiFe2O4 using 1,4-phenylenediboronic acid, which is promising for ppb-level toluene detection.

Effect of temperature on the aggregation kinetic and interaction mode of asphaltene in Toluene-Heptane system at molecular level using molecular dynamics (MD) simulation

For many years, the asphaltene aggregation has been the research focus in the petroleum industry. However, few widely held beliefs have achieved on the microscopic process of asphaltene aggregation. To this end, molecular dynamics (MD) simulation was adapted to study the asphaltene aggregation in asphaltene-heptane-toluene system, and the interaction between asphaltene molecules during this process was also revealed from the density distribution, mean square displacement (MSD), diffusion coefficient, interaction energy and cohesive energy density (CED). Three main findings were made: (1) The increase in temperature can increase the diffusion rate of asphaltene molecules. However, it has a greater effect on the diffusion rate of asphaltenes in the heptane-rich system, while it has little effect in the toluene-rich system. (2) In system with more heptane, the increase of temperature will reduce the aggregation of asphaltene molecules, while the increase of temperature will promote the aggregation of asphaltene molecules in system with more toluene. (3) Interaction energy and cohesive energy density show that the interaction between asphaltenes and toluene in the toluene-rich system restricts the movement of asphaltene molecules, and the toluene molecules tend to surround asphaltene molecules to form a “Cage”, creating the illusion of increased density and aggregation of asphaltenes. The findings can help for understanding of the interaction between asphaltene molecules, and provide theoretical support for the flow assurance in asphaltene oil production systems.

A novel type microporous adsorbent based on single-walled carbon nanotubes assembled by toluene molecules for methane storage

A novel type microporous adsorbent based on single-walled carbon nanotubes assembled by toluene molecules for methane storage

Cineole – Decanoic acid hydrophobic natural Deep eutectic solvent for toluene absorption

The hydrophobic deep eutectic solvent formed by the equimolar combination of natural compounds cineole and decanoic acid is studied as an archetypical compound for aromatics (toluene) solubilization/extraction purposes. The physicochemical properties of toluene solutions in the solvents are studied as a function of composition and temperature. The nature of intermolecular forces between toluene and solvent molecules is analyzed using a minimal clusters approach through quantum chemistry methods. Classical molecular dynamics simulation on toluene solution allowed us to infer nanoscopic behavior and structuring of the toluene mixtures using static and dynamic approaches. Likewise, the possible biological effects of the considered solvent are studied considering its effect on lipid bilayers as a model of plasma membranes using coarse-grained molecular dynamics methods. The reported results provide a multiscale combined experimental and computational characterization of hydrophobic Deep Eutectics as suitable solvents for aromatic hydrocarbons.

Promoting Pd/Al2O3 catalysts for toluene combustion by DBD plasma treating in different working gas atmospheres

To investigate the effects of plasma treatment on supported precious metals for VOCs combustion, a series of 1%Pd/Al2O3 catalysts were synthesized by DBD plasma treating in different working gases (H2/Ar, O2, N2, Air) and with reversed calcination sequences. It is revealed that both the working gas and treating sequence can alter the Pd dispersion degree, valence states and the concentration of surface acid sites, which subsequently impacts the catalytic activity. Usually, a Pd/Al2O3 catalyst with a higher active Pd surface area shows higher toluene combustion activity, due to the promoted ability to adsorb and activate toluene molecules. Therefore, Pd dispersion degree is the main factor to determine the reactivity of Pd/Al2O3 catalysts. Moreover, H2/Ar plasma treating can effectively create Pd0 sites, which is favorable to toluene and O2 molecule adsorption and activition. Due to the combination of these two factors, 1%Pd/Al2O3-C-H2P displays the best activity among all the samples.

Cooperativity in molecular recognition of feet-to-feet-connected biscavitands

Abstract Octaphosphonate biscavitand and self-folding deep biscavitand show strong positive and negative cooperativity, respectively. The mechanism of the cooperativity is discussed in terms of thermodynamic parameters and the detailed structure of the host-guest complexes. The two cavitand units of both biscavitands are tightly connected via four butylene linkers; thus, they are conformationally coupled, with the first guest binding information transferred to the resting-state cavities. This preorganization modulates the successive guest binding process in strong positive and negative cooperative manners, even though they display structural similarity. The first guest complexation always preorganizes the resting-state cavities where an existing water cluster and a toluene molecule are enthalpically stabilized. Successive guest complexation competes with the water cluster or a toluene molecule, reducing enthalpy gains. However, the desolvation upon successive guest binding processes liberate the solvents within the resting-state cavities. The water cluster is composed of 12 water molecules that are released upon successive guest complexation, resulting in a large entropy benefit. In contrast, toluene desolvation results in a limited entropy benefit. The difference in entropy benefits directs the strong positive or negative cooperativity of the structurally similar biscavitands.

Swellable Array Strategy Based on Designed Flexible Double Hypercross-linked Polymers for Synergistic Adsorption of Toluene and Formaldehyde.

High-capacity adsorption and removal of complex volatile organic compounds (VOCs) from real-world environments is a tough challenge for researchers. Herein, a swellable array adsorption strategy was proposed to realize the synergistic adsorption of toluene and formaldehyde on the flexible double hypercross-linked polymers (FD-HCPs). FD-HCPs exhibited multiple adsorption sites awarded by a hydrophobic benzene ring/pyrrole ring and a hydrophilic hydroxyl structural unit. The array benzene ring, hydroxyl, and pyrrole N sites in FD-HCPs effectively captured toluene and formaldehyde molecules through π-π conjugation and electrostatic interaction and weakened their mutual competitive adsorption. Interestingly, the strong binding force of toluene molecules to the skeleton deformed the pore structure of FD-HCPs and generated new adsorption microenvironments for the other adsorbate. This behavior significantly improved the adsorption capacity of FD-HCPs for toluene and formaldehyde by 20% under multiple VOCs. Moreover, the pyrrole group in FD-HCPs greatly hindered H2O molecule diffusion in the pore, thus efficiently weakening the competitive adsorption of H2O toward VOCs. These fascinating properties enabled FD-HCPs to achieve synergistic adsorption for multicomponent VOC vapor under a highly humid environment and overcame single-species VOC adsorption properties on state-of-the-art porous adsorbents. This work provides the practical feasibility of synergistic adsorption to remove complex VOCs in real-world environments.

BTEX and PAH contributions to Lake Kinneret water: a seasonal-based study of volatile and semi-volatile anthropogenic pollutants in freshwater sources.

Benzene , toluene, ethylbenzene, and xylenes (BTEX) BTEX molecules are toxic components, ubiquitous in the environment, often found in concentrations- a few orders of magnitude higher than the well-studied PAHs levels. This fact is demonstrated in either crude oil, fuels, water, and air samples. BTEX studies focus mainly on the airborne levels of these molecules, while their waterborne presence is understudied. In this study, BTEX levels were assessed at Lake Kinneret, Israel. As a result, 0-1.5ppb of BTEX was recorded in five stations (2021-2022). Elevated BTEX levels (3-10ppb) were recorded at the northern rivers nourishing this lake, implying the existence of remote polluting sources. Transect air samplings of BTEX conducted at the lake next to the bathing season of 2021 revealed airborne BTEX levels between 0.8 and 10µg/m3, peaking up close to the bathing season, yet inconsistent with the BTEX water level trend. Lake water samples collected next to Tiberias city outfalls following the "Carmel" rainstorm showed elevated concentrations of BTEX up to 35ppb and PAHs up to 0.47ppb with an urban isotopic signal. The remote station's PAHs levels were less than one order of magnitude, with a distinct rural isotopic signal. Additionally, a human-specific microbial marker revealed increased sewer contributions at some of theurbansites. The results of this study show that a wide area dispersion of low atmospheric BTEX levels exists in the lake's perimeter. The dispersion rate is most likely influenced by season-based factors, e.g., motors and biomass fires. The unstudied waterborneBTEX levels in this lake are influenced by rivers, city runoff, and other yet unknown factors that may contribute to the sedimentation of these components. This process may result in a chronic pollution state. Despite the BTEX's medium-low solubility and high volatility, its under-evaluated waterborne transportation may lead to high toxic levels following bioaccumulation.

Reactions of Low-Valent Gallium Species with Organic Azides: Formation of Imido-, Azoimido-, and Tetrazene Complexes.

The reactivity of two α-diimine-ligated digallanes, [L2-Ga-GaL2-] (La = [(2,6-iPr2C6H3)NC(CH3)]2, dpp-dad, 1; Lb = 1,2-[(2,6-iPr2C6H3)NC]2C10H6, dpp-bian, 2), and a gallylene, [(La)2-GaNa(THF)3] (3), toward organic azides was studied. Reaction of digallane 1 or 2 with trimethylsilyl azide (Me3SiN3), 2-azido-benzonitrile (2-CNC6H4N3), or tosylazide (TosN3) results in imido-bridged complexes, [(La)·-Ga(μ-NSiMe3)2Ga(La)·-] (4) [(Lb)·-Ga(μ-NSiMe3)2Ga(Lb)·-] (5), [(Lb)·-Ga(μ-2-CNC6H4N)2Ga(Lb)·-] (6), and [(Lb)·-Ga(μ-NTos)2Ga(Lb)·-] (7), with elimination of dinitrogen. Treatment of 1 or 2 with 1-adamantyl azide (1-AdN3), on the other hand, affords the unsymmetrical dinuclear complexes [(La)·-Ga(NAd)(N3Ad)Ga(La)·-] (8) and [(Lb)·-Ga(NAd)(N3Ad)Ga(Lb)·-] (9), which contain both imido and triazene bridges. Different from the Ga(II) complexes 1 and 2, the reactions of Ga(I) species 3 with benzylazide or trimethylsilyl azide result in the tetrazene complex {Na(THF)}2[(La)2-Ga(benzyl-N4-benzyl)]2 (10) and amide complex {Na(THF)4}[(La)2-Ga(NHSiMe3)(benzyl)] (11). It is likely that these latter transformations proceed via the transient formation of the corresponding Ga═N imide complex, which undergoes either cycloaddition with a second azide (to form 10) or activation of the C-H bond of methyl in one solvent toluene molecule (to yield 11).

Aromatic Volatile Organic Compounds Adsorption on Tungsten Diselenide Monolayer

In this work, we performed a density functional theory calculation to systematically investigate the adsorption and evaluate the adsorption performance of aromatic volatile organic compounds, benzene and toluene, on WSe2 monolayer. The most favourable adsorption configurations of gas molecules with the parallel orientation of the benzene ring to the substrate surface are explored by computing the binding energies as a function of spatial coordinates and carefully optimizing geometrical structures. The calculations pointed out that gas molecules could diffuse across the substrate along the diffusion paths with quite low diffusion potential barriers, about 180 meV for benzene and 130 meV for toluene molecules. We found that both gases are physisorbed on WSe2 monolayer with moderate adsorption energies, short recovery times, and large response lengths. The gas adsorption causes the bandgap reduction of 26 meV and a slight work function increase of the substrate. There is a charge transfer from the substrate onto the gas molecules, this may cause a resistance decrease of the p-type semiconductor substrate. WSe2 monolayer is quite sensitive to benzene and toluene, and could be suggested as an aromatic gas sensing material.

Facile synthesis of β-MnO2 via ozone oxidation for enhanced performance of toluene oxidation

In this work, a series of β-MnO2 catalysts is directly synthesized via ozone oxidation using the hydrothermal method. And the effect of hydrothermal temperature on catalytic activities of toluene oxidation is investigated. The catalytic evaluation shows that O3(HT)-160 prepared at 160 °C of hydrothermal temperature exhibits the best catalytic activity of toluene oxidation compared with other catalysts. By comparison of physicochemical properties, O3(HT)-160 possesses a bigger specific surface area and larger pore volume, which are beneficial to the adsorption and diffusion of toluene molecules. Meanwhile, O3(HT)-160 performs lower reductive temperature, higher ratio of Mn4+/(Mn3++ Mn2+) and Olatt/Oads and much more oxygen vacancies, which contributes to the cycle of redox ability, the complete oxidation of intermediates and the activation of oxygen. Moreover, combined with the results of in-situ DRIFTS and TD/GC–MS, the main intermediates are benzyl alcohol, benzaldehyde, benzoic acid and propylene glycol during toluene oxidation on O3(HT)-160. Furthermore, the catalytic mechanism is proposed for toluene oxidation on O3(HT)-160. This work provides a more convenient and simpler method to prepare β-MnO2 using ozone as the oxidizer compared with potassium permanganate and potassium persulfate.

Solvent-induced MultiStimuli-Responsive properties of cyano-substituted Oligo(p-phenylene vinylene) derivatives

Stimuli-responsive luminescent materials with controllable photophysical properties have attracted much attention because of their potential applications in smart materials and devices. Through the incorporation of electron-donating (NPh3) and electron-withdrawing (CN) functionalities, two donor-acceptor luminophores C4OPV-TPA and C8OPV-TPA bearing two different alkyl chain lengths were prepared and fully characterized. Although both C4OPV-TPA and C8OPV-TPA exhibited similar luminescence and AIEE effects in solution with intramolecular charge-transfer (ICT) transition, remarkable differences were observed in the self-assemble state. Specifically, precipitation of C4OPV-TPA into toluene and CH2Cl2, respectively, afforded two distinctly crystallines, with one in orange color (O-state) and the other in red color (R-state). Notably, C4OPV-TPA in O-state exhibited stimuli-responsive behaviors in solid state, which were ascribed to the formation of an inclusion complex with toluene molecules. Under thermal heating and mechanical grinding, toluene was released from crystal lattice of luminophore accompanied with red-shifted emission spectra. The molecular packing of C4OPV-TPA in R-state, on the other hand, adopted stronger H-aggregates without inclusion of CH2Cl2 molecules, which was further investigated by X-ray diffraction. These excellent optical properties enabled C4OPV-TPA serve as a fluorescent ink for thermal-responsive data storage device.

Разработка методов получения углеродных адсорбентов на основе Ангренского угля и нефтяных остатков

Currently, activated carbon adsorbents are widely used in the world for industrial wastewater treatment from various organic compounds, sorption of heavy metal ions and life-threatening radioactive substances. Carbon adsorbents with hydrophobic properties are mainly modified based on the brown coal, coke, scape, and bark of plants. The methods of manufacturing coal adsorbents based on Angren coal, petroleum coke and asphaltenes are listed. The physicochemical composition and complete thermodynamic properties of the activated carbon adsorbent were studied. It was found that during the heat treatment of mixtures of carbonaceous raw materials, its mass is lost with increasing temperature. At the same time, the adsorption activity of iodine increases with increasing temperature. Depending on the change in temperature of the obtained carbon adsorbent samples, the calculated surface area with respect to iodine is 280.7 m2/g with a weight loss of 0.2 g. The differential heat of adsorption, isotherm, molar entropy and thermokinetics of the benzene and toluene molecules studied in the article are calculated. The adsorption of 4.5 mmol/g of benzene and 3.5 mmol/g of toluene on the activated carbon adsorbent was determined. It is noted that during the adsorption of benzene and toluene by the obtained adsorbent from activated carbon, the differential heat of reaction gradually decreases. When recalculating the isothermal adsorption of benzene and toluene on activated carbon according to the equation of the volumetric theory of micropore saturation, it was obtained that 84.5 % of benzene and 94.2 % of toluene were adsorbed on the pores of the adsorbent.

Seed-mediated synthesis of a modified micro-mesoporous MIL-101(Cr) for improved benzene and toluene adsorption at room conditions

The modification of metal-organic frameworks (MOFs) for enhanced volatile organic compounds (VOCs) removal is a huge challenge. Therefore, it is of great importance to find a proper strategy to tune the porosity of MOFs and their VOCs removal performance. In this study, we report a novel seed-mediated synthesis strategy using a low-cost and heteroatom-rich carbon structure (MIC-COOH) to prepare hierarchical micro-mesoporous MIL-101(Cr). Different amounts of MIC-COOH were applied to investigate the efficiency of seed concentration on the fundamental specification of the created hierarchical MIL-101(Cr) and its benzene and toluene uptake. The results showed that the increase of MIC-COOH significantly enhanced the mesoporous volume in the MOF structure, resulting in the creation of large surface area (up to 2971.5 m2/g) and high pore volume (up to 2.21 cm3/g). MIL@MIC-4% nanostructure exhibited 235.3 ± 0.05 and 291.6 ± 0.04 wt% adsorption efficiency for benzene and toluene, respectively, which are ⁓3.0 and 4.1 times greater than those of pristine MIL-101(Cr). It also exhibited higher cyclic adsorption efficiency than that of the pristine MIL-101(Cr) after five consecutive adsorption-desorption cycles. The uptake behavior of benzene and toluene on the modified MIL@MIC structure was also perused by applying density functional theory (DFT) calculations. According to the findings, it was revealed that the cooperative charge transfers between MIL-101(Cr) and MIC-COOH through the structure can play an efficient role in the enhanced uptake of benzene and toluene molecules.

Packing structure and non-classical hydrogen bonding interactions of the toluene solvate crystal of 1,8-bis(4-methylbenzoyl)naphthalene-2,7-diyl dibenzoate: Role of toluene molecule in determination of the spatial arrangement of the major constituent molecules

The toluene solvate crystal of the titled highly congested aromatic ketone-ester compound has been subjected to crystal structural analysis from the viewpoints of the clarification of distribution feature of effective non-classical hydrogen bonds and the retention and perturbation of the symmetric nature. The two independent molecules of the title naphthalene derivative, which bears two aroyl groups at the adjacent inner positions and two benzoyloxy groups at the neighboring β-positions, and one disordered solvent toluene molecule are incorporated in the asymmetric unit of P21 /c (Z′= 2). In the packing of the solvate crystal, the solvent toluene molecule plays the multi roles of hydrogen donor/acceptor for C–H…π non-classical hydrogen bonds and hydrogen donor for C–H…O = C ones. On the other hand, the role of other benzene rings of the parts of the title compound molecules is confined. The 4-methylbenzoyl groups situated at the molecular inner positions mainly play the role of the hydrogen donor of C–H…π non-classical hydrogen bond. The benzoyloxy groups that extend outward from the molecular body mainly act as the hydrogen acceptors of C–H…O and C–H…π non-classical hydrogen bonds. The naphthalene ring moderately contributes as the hydrogen acceptor for C–H…π non-classical hydrogen bonds and as the hydrogen donor for C–H…O non-classical hydrogen bonds. The roles of the toluene molecule are not limited to a simple filler for the void among the major constituent molecules but proved to position at the pseudo-centrosymmetric center of the counter-configurated pair of molecules of the independent major component compounds to concentrate the effective non-classical hydrogen bonds.

Pressure-driven flow behavior of small molecules through a carbon nanotube

In this research, the flow behavior of ring and chain molecules through a carbon nanotube (CNT) driven by pressure has been investigated using molecular dynamics (MD) simulations. We have examined the distribution of fluid molecules and the flow process confined in the CNT. We also calculated the radial count profiles, the axial density distributions, molecular conformation and fluid flux. Our results revealed that a sudden pressure applied on fluid molecules will lead to inrush of fluid inside nanoscale channels. The fluid molecules confined in the CNT formed an interfacial layer near the CNT inner surface. That of toluene system is closer to the CNT wall than heptane system. The results also indicated that plane of toluene molecules in interfacial layer is parallel to the CNT wall. The distributions of the others are disordered. The heptane molecules formed four cylindrical layers inside the CNT. The molecules in interfacial layer are parallel to the CNT wall.

Fully Atomistic Molecular Dynamics Simulation of a TIPS-Pentacene:Polystyrene Mixed Film Obtained via the Solution Process

Organic thin-film transistors using small-molecule semiconductor materials such as 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-P) have been recently studied for the production of flexible and printed electronic devices. Blending a semiconductor with an insulating polymer, such as polystyrene, is known to improve the device performance; however, its molecular-level structure remains unknown. In this study, we performed molecular dynamics (MD) simulations on a mixed system of TIPS-P and atactic polystyrene (aPS) with fully atomistic models to understand the structure of the mixed thin film at the molecular level and the influence on the device properties. To reproduce the deposition from the solution, we gradually reduced the number of toluene molecules in the simulation. The dynamic characteristics of the system, mean squared displacement, diffusion coefficient, density profile, and P2 order parameter were analyzed. Some of the simulated systems reached the equilibrium state. In these systems, the simulated structures suggested the presence of more TIPS-P molecules on the surface than inside the bulk, even at the low molecular weight of aPS, where phase separation was not observed experimentally. The results of the fully atomistic MD simulations are also a basis for the coarse-grained model to increase the speed of the MD simulation.

Neutron reflectivity study on the nanostructure of PMMA chains near substrate interfaces based on contrast variation accompanied with small molecule sorption.

In the case of poly(methyl methacrylate) (PMMA) thin films on a Si substrate, thermal annealing induces the formation of a layer of PMMA chains tightly adsorbed near the substrate interface, and the strongly adsorbed PMMA remains on the substrate, even after washing with toluene (hereinafter called adsorbed sample). Neutron reflectometry revealed that the concerned structure consists of three layers: an inner layer (tightly bound on the substrate), a middle layer (bulk-like), and an outer layer (surface) in the adsorbed sample. When an adsorbed sample was exposed to toluene vapor, it became clear that, between the solid adsorption layer (which does not swell) and bulk-like swollen layer, there was a "buffer layer" that could sorb more toluene molecules than the bulk-like layer. This buffer layer was found not only in the adsorbed sample but also in the standard spin-cast PMMA thin films on the substrate. When the polymer chains were firmly adsorbed and immobilized on the Si substrate, the freedom of the possible structure right next to the tightly bound layer was reduced, which restricted the relaxation of the conformation of the polymer chain strongly. The "buffer layer" was manifested by the sorption of toluene with different scattering length density contrasts.

Basic thermodynamic characteristics of toluene adsorption in Cu2+ZSM-5 Zeolite

This paper presents the results of isotherms and basic (ΔH, ΔF and ΔS) thermodynamic characteristics of toluene adsorption in CuZSM-5 zeolite. For measurements of isotherms and differential heat of adsorption, a system consisting of a universal high-vacuum adsorption unit and an attached differential modified Tian-Calve microcalorimeter DAC-1-1A was used to provide direct quantitative and qualitative characteristics of the nature and forces of adsorption interaction. The correlation between the adsorption-energy characteristics wasfound and the molecular mechanismof toluene adsorption in CuZSM-5 zeolite in the whole filling region was revealed. Toluene adsorbed in CuZSM-5 zeolite is located in the first coordination sphere with Cu2+ cation, forming two-dimensional complexes. It was found that the charge density significantly affects the mechanism, the energy of adsorption and the number of adsorbed molecules. It was determined that the average molar entropy of toluene adsorption in CuZSM5 zeolite indicates that the mobility of toluene molecules in zeolite is below the liquid phase and close to that of the solid phase, indicating that the mobility of toluene molecules on cations is strongly inhibited. This work shows how calorimetric data can be used to complement crystal structure results and detect subtle adsorbent/adsorbate interactions at the molecular level.