Hybrid Ultramicroporous Materials Research Articles

Achieving Molecular Sieving of CO2 from CH4 by Controlled Dynamical Movement and Host-Guest Interactions in Ultramicroporous VOFFIVE-1-Ni by Pillar Substitution.

Engineering the building blocks in metal-organic materials is an effective strategy for tuning their dynamical properties and can affect their response to external guest molecules. Tailoring the interaction and diffusion of molecules into these structures is highly important, particularly for applications related to gas separation. Herein, we report a vanadium-based hybrid ultramicroporous material, VOFFIVE-1-Ni, with temperature-dependent dynamical properties and a strong affinity to effectively capture and separate carbon dioxide (CO2) from methane (CH4). VOFFIVE-1-Ni exhibits a CO2 uptake of 12.08 wt % (2.75 mmol g-1), a negligible CH4 uptake at 293 K (0.5 bar), and an excellent CO2-over-CH4 uptake ratio of 2280, far exceeding that of similar materials. The material also exhibits a favorable CO2 enthalpy of adsorption below -50 kJ mol-1, as well as fast CO2 adsorption rates (90% uptake reached within 20 s) that render the hydrolytically stable VOFFIVE-1-Ni a promising sorbent for applications such as biogas upgrading.

Cross-Linking CdSO4-Type Nets with Hexafluorosilicate Anions to Form an Ultramicroporous Material for Efficient C2H2/CO2 and C2H2/C2H4 Separation.

A 44.610.8 topology hybrid ultramicroporous material (HUM), {[Cu1.5F(SiF6)(L)2.5]·G}n, (L = 4,4'-bisimidazolylbiphenyl, G = guest molecules), 1, formed by cross-linking interpenetrated 3D four-connected CdSO4-type nets with hexafluorosilicate anions is synthesized and evaluated in the context of gas sorption and separation herein. 1 is the first HUM functionalized with two different types of fluorinated sites (SiF6 2- and F- anions) lining along the pore surface. The optimal pore size (≈5Å) combining mixed and high-density electronegative fluorinated sites enable 1 to preferentially adsorb C2H2 over CO2 and C2H4 by hydrogen bonding interactions with a high C2H2 isosteric heat of adsorption (Qst) of ≈42.3kJmol-1 at zero loading. The pronounced discriminatory sorption behaviors lead to excellent separation performance for C2H2/CO2 and C2H2/C2H4 that surpasses many well-known sorbents. Dynamic breakthrough experiments are conducted to confirm the practical separation capability of 1, which reveal an impressive separation factor of 6.1 for equimolar C2H2/CO2 mixture. Furthermore, molecular simulation and density functional theory (DFT) calculations validate the strong binding of C2H2 stems from the chelating fix of C2H2 between SiF6 2- anion and coordinated F- anion.

Crystal Engineering of a New Hexafluorogermanate Pillared Hybrid Ultramicroporous Material Delivers Enhanced Acetylene Selectivity.

Hybrid ultramicroporous materials (HUMs), metal-organic platforms that incorporate inorganic pillars, are a promising class of porous solids. A key area of interest for such materials is gas separation, where HUMs have already established benchmark performances. Thanks to their ready compositional modularity, we report the design and synthesis of a new HUM, GEFSIX-21-Cu, incorporating the ligand pypz (4-(3,5-dimethyl-1H-pyrazol-4-yl)pyridine, 21) and GeF62- pillaring anions. GEFSIX-21-Cu delivers on two fronts: first, it displays an exceptionally high C2H2 adsorption capacity (≥5 mmol g-1) which is paired with low uptake of CO2 (<2 mmol g-1), and, second, a low enthalpy of adsorption for C2H2 (ca. 32 kJ mol-1). This combination is rarely seen in the C2H2 selective physisorbents reported thus far, and not observed in related isostructural HUMs featuring pypz and other pillaring anions. Dynamic column breakthrough experiments for 1:1 and 2:1 C2H2/CO2 mixtures revealed GEFSIX-21-Cu to selectively separate C2H2 from CO2, yielding ≥99.99% CO2 effluent purities. Temperature-programmed desorption experiments revealed full sorbent regeneration in <35 min at 60 °C, reinforcing HUMs as potentially technologically relevant materials for strategic gas separations.

Crystal engineering of a new platform of hybrid ultramicroporous materials and their C2H2/CO2 separation properties.

Hybrid ultramicroporous materials (HUMs) comprised of combinations of organic and inorganic linker ligands are a leading class of physisorbents for trace separations involving C1, C2 and C3 gases. First generation HUMs are modular in nature since they can be self-assembled from transition metal cations, ditopic linkers and inorganic "pillars", as exemplified by the prototypal variant, SIFSIX-3-Zn (3 = pyrazine, SIFSIX = SiF6 2-). Conversely, HUMs that utilise chelating ligands such as ethylenediamine derivatives are yet to be explored as sorbents. Herein, we report the structures and sorption properties of two HUMs based upon the chelating ligand N 1,N 2-bis(pyridin-4-ylmethyl)ethane-1,2-diamine (enmepy), [Zn(enmepy)(SiF6)] n (SIFSIX-24-Zn) and [Zn(enmepy)(SO4)] n (SOFOUR-2-Zn). These HUMs are isostructural and exhibit high C2H2 uptakes of 85 cm3 g-1 (3.79 mmol g-1) and 79 cm3 g-1 (3.52 mmol g-1), and C2H2/CO2 IAST selectivities of 7.4 and 8.1 (1 bar, 1 : 1 mixture, 298 K), respectively. Dynamic column breakthrough experiments resulted in separation factors of 5.26 and 2.05, and CO2 effluent purities of 99.991 and 99.989%, respectively. Temperature programmed desorption experiments at 60 °C resulted in rapid desorption of CO2, followed by fuel grade C2H2 (>98%), affording productivities of 9.45 and 7.96 L kg-1 and maximum C2H2 outlet purities of 99.92% and 99.66%, respectively. This study introduces the use of diamine chelating ligands in HUMs for gas separations through two parent sorbents that are prototypal for families of related materials, one of which, SOFOUR-2-Zn, uses the earth-friendly sulfate anion as a pillar.

Highly Productive C3H4/C3H6 Trace Separation by a Packing Polymorph of a Layered Hybrid Ultramicroporous Material.

Ultramicroporous materials can be highly effective at trace gas separations when they offer a high density of selective binding sites. Herein, we report that sql-NbOFFIVE-bpe-Cu, a new variant of a previously reported ultramicroporous square lattice, sql, topology material, sql-SIFSIX-bpe-Zn, can exist in two polymorphs. These polymorphs, sql-NbOFFIVE-bpe-Cu-AA (AA) and sql-NbOFFIVE-bpe-Cu-AB (AB), exhibit AAAA and ABAB packing of the sql layers, respectively. Whereas NbOFFIVE-bpe-Cu-AA (AA) is isostructural with sql-SIFSIX-bpe-Zn, each exhibiting intrinsic 1D channels, sql-NbOFFIVE-bpe-Cu-AB (AB) has two types of channels, the intrinsic channels and extrinsic channels between the sql networks. Gas and temperature induced transformations of the two polymorphs of sql-NbOFFIVE-bpe-Cu were investigated by pure gas sorption, single-crystal X-ray diffraction (SCXRD), variable temperature powder X-ray diffraction (VT-PXRD), and synchrotron PXRD. We observed that the extrinsic pore structure of AB resulted in properties with potential for selective C3H4/C3H6 separation. Subsequent dynamic gas breakthrough measurements revealed exceptional experimental C3H4/C3H6 selectivity (270) and a new benchmark for productivity (118 mmol g-1) of polymer grade C3H6 (purity >99.99%) from a 1:99 C3H4/C3H6 mixture. Structural analysis, gas sorption studies, and gas adsorption kinetics enabled us to determine that a binding "sweet spot" for C3H4 in the extrinsic pores is behind the benchmark separation performance. Density-functional theory (DFT) calculations and Canonical Monte Carlo (CMC) simulations provided further insight into the binding sites of C3H4 and C3H6 molecules within these two hybrid ultramicroporous materials, HUMs. These results highlight, to our knowledge for the first time, how pore engineering through the study of packing polymorphism in layered materials can dramatically change the separation performance of a physisorbent.

Efficient separation of C4 olefins with fluorinated anion-pillared hybrid ultramicroporous materials by gate-opening and size-sieving effect

In the petrochemical industry, the separation of C4 olefins is crucial but a challenging and energy-intensive process. In this study, two fluorinated anion-pillared hybrid ultramicroporous materials (HUMs), namely KAUST-7 (NbOFFIVE-1-Ni) and KAUST-8 (AlFFIVE-1-Ni), were explored for the efficient separation of ternary C4 olefin mixtures (C4H6/n-C4H8/iso-C4H8) via gate-opening and size-sieving effects. KAUST-7, with a narrow and flexible pore window that completely excludes iso-C4H8, but allows for the absorption of C4H6 and n-C4H8 through gate-opening effects, with a preferential adsorption of C4H6 due to its easier access to the channel. KAUST-8, on the other hand, with a larger pore window size and the strong H-bond interactions between the electronegative fluorine atoms from inorganic anion pillar and the C4 olefin molecules, efficiently separates iso-C4H8 from C4 olefins, as the adsorption of both C4H6 and n-C4H8 is significantly enhanced while iso-C4H8 retains much lower adsorption capacity. The relationship between the structures and separation properties of these materials is discussed, providing insight into the development of efficient separation materials. Fixed bed breakthrough experiments verify the excellent separation performances of KAUST-7 and KAUST-8 for C4H6/n-C4H8/iso-C4H8, highlighting their potential for industrial applications.

A new perchlorate-based hybrid ultramicroporous material with rich bare oxygen atoms for high C2H2/CO2 separation

Adsorptive separation of acetylene (C2H2) from carbon dioxide (CO2) is of great significance in petrochemical industry, but still remains as a daunting challenge by reason of their very similar molecular sizes/shapes and physical properties. Herein, we reported a new perchlorate-based hybrid ultramicroporous material ZJU-194 that features the unique flexible-robust network decorated with rich bare oxygen atoms. By integrating the refined pore space as well as specific binding sites, the activated ZJU-194 (ZJU-194a) enables a selective two-step gate-opening adsorption toward C2H2, but blocks off the further uptake of CO2. It thus exhibits a very high C2H2/CO2 selectivity (22.4) at ambient conditions, which is superior to most reported MOF materials. Its complete separation for 50/50 C2H2/CO2 mixtures is further evidenced by the dynamic breakthrough experiments.

Pillar Modularity in fsc Topology Hybrid Ultramicroporous Materials Based upon Tetra(4-pyridyl)benzene.

Hybrid ultramicroporous materials (HUMs) are porous coordination networks composed of combinations of organic and inorganic linker ligands with a pore diameter of <7 Å. Despite their benchmark gas sorption selectivity for several industrially relevant gas separations and their inherent modularity, the structural and compositional diversity of HUMs remains underexplored. In this contribution, we report a family of six HUMs (SIFSIX-22-Zn, TIFSIX-6-Zn, SNFSIX-2-Zn, GEFSIX-4-Zn, ZRFSIX-3-Zn, and TAFSEVEN-1-Zn) based on Zn metal centers and the tetratopic N-donor organic ligand tetra(4-pyridyl)benzene (tepb). The incorporation of fluorinated inorganic pillars (SiF62–, TiF62–, SnF62–, GeF62–, ZrF62–, and TaF72–, respectively) resulted in (4,6)-connected fsc topology as verified using single-crystal X-ray diffraction. Pure-component gas sorption studies with N2, CO2, C2H2, C2H4, and C2H6 revealed that the large voids and narrow pore windows common to all six HUMs can be leveraged to afford high C2H2 uptakes while retaining high ideal adsorbed solution theory (IAST) selectivities for industrially relevant gas mixtures: >10 for 1:99 C2H2/C2H4 and >5 for 1:1 C2H2/CO2. The approach taken, systematic variation of pillars with retention of structure, enables differences in selectivity to be attributed directly to the choice of the inorganic pillar. This study introduces fsc topology HUMs as a modular platform that is amenable to fine-tuning of structure and properties.

Kinetic-Sieving of Carbon Dioxide from Acetylene through a Novel Sulfonic Ultramicroporous Material.

The engineering and tailoring of porous materials to realize the precise discrimination of CO2 and C2 H2 , with almost identical kinetic diameters, is a challenging task. We herein report the first example of the kinetic-sieving of relatively larger molecule of C2 H2 from CO2 by a novel sulfonic anion-pillared hybrid ultramicroporous materials of ZU-610a. Specifically, ZU-610 constructed from copper(II), isonicotinic acid and 1,2-ethanedisulfonic acid is synthesized and shows the preferential affinity for C2 H2 over CO2 . After the post-synthetic heat treatment of ZU-610, ZU-610a with a contracted aperture is obtained. Interestingly, the C2 H2 -selctive ZU-610 was reversed to the CO2 -selective ZU-610a. High purity C2 H2 (>99.5 %) could be directly obtained from the dynamic breakthrough experiments on an equimolar C2 H2 /CO2 mixture at 298 K. This study provides guidance for the design of adsorbents aimed at separation systems with similar kinetic diameter.

Kinetic‐Sieving of Carbon Dioxide from Acetylene through a Novel Sulfonic Ultramicroporous Material

AbstractThe engineering and tailoring of porous materials to realize the precise discrimination of CO2 and C2H2, with almost identical kinetic diameters, is a challenging task. We herein report the first example of the kinetic‐sieving of relatively larger molecule of C2H2 from CO2 by a novel sulfonic anion‐pillared hybrid ultramicroporous materials of ZU‐610a. Specifically, ZU‐610 constructed from copper(II), isonicotinic acid and 1,2‐ethanedisulfonic acid is synthesized and shows the preferential affinity for C2H2 over CO2. After the post‐synthetic heat treatment of ZU‐610, ZU‐610a with a contracted aperture is obtained. Interestingly, the C2H2‐selctive ZU‐610 was reversed to the CO2‐selective ZU‐610a. High purity C2H2 (&gt;99.5 %) could be directly obtained from the dynamic breakthrough experiments on an equimolar C2H2/CO2 mixture at 298 K. This study provides guidance for the design of adsorbents aimed at separation systems with similar kinetic diameter.

Enhanced ethylene transport of mixed-matrix membranes by incorporating anion-pillared hybrid ultramicroporous materials via in situ growth

The separation of ethylene/ethane based on mixed-matrix membranes (MMMs) is a promising yet challenging task. In this work, high-performing GeFSIX-3-Ni/6FDA-DAM MMMs consisting of anion-pillared hybrid material GeFSIX-3-Ni (also termed ZU-36-Ni, GeFSIX = hexafluorogermanate, 3 = pyrazine) and 6FDA-DAM were synthesized via a simple in situ method, which surpasses 2013 upper bound for C2H4/C2H6 separation. Further investigations revealed that the interfacial compatibility between GeFSIX-3-Ni and 6FDA-DAM was improved with the enhancement of hydrogen bonds and the regulated small particle size (<50 nm). Both single- and mixed gas separation experiments confirmed that the separation performance of 10 wt% GEF-PI-S MMMs (GEF = GeFSIX-3-Ni, PI = 6FDA-DAM, S = in situ method) surpassed the C2H4/C2H6 upper bound in terms of C2H4 permeability (131.4 Barrer) and C2H4/C2H6 selectivity (3.80) for equimolar C2H4/C2H6 mixed gas. This work provides insights into more efficient way of obtaining defect-free MMMs with high performances for diversified separations.

CO2 Capture by Hybrid Ultramicroporous TIFSIX-3-Ni under Humid Conditions Using Non-Equilibrium Cycling.

Although pyrazine‐linked hybrid ultramicroporous materials (HUMs, pore size <7 Å) are benchmark physisorbents for trace carbon dioxide (CO2) capture under dry conditions, their affinity for water (H2O) mitigates their carbon capture performance in humid conditions. Herein, we report on the co‐adsorption of H2O and CO2 by TIFSIX‐3‐Ni—a high CO2 affinity HUM—and find that slow H2O sorption kinetics can enable CO2 uptake and release using shortened adsorption cycles with retention of ca. 90 % of dry CO2 uptake. Insight into co‐adsorption is provided by in situ infrared spectroscopy and ab initio calculations. The binding sites and sorption mechanisms reveal that both CO2 and H2O molecules occupy the same ultramicropore through favorable interactions between CO2 and H2O at low water loading. An energetically favored water network displaces CO2 molecules at higher loading. Our results offer bottom‐up design principles and insight into co‐adsorption of CO2 and H2O that is likely to be relevant across the full spectrum of carbon capture sorbents to better understand and address the challenge posed by humidity to gas capture.

CO2 Capture by Hybrid Ultramicroporous TIFSIX‐3‐Ni under Humid Conditions Using Non‐Equilibrium Cycling

AbstractAlthough pyrazine‐linked hybrid ultramicroporous materials (HUMs, pore size &lt;7 Å) are benchmark physisorbents for trace carbon dioxide (CO2) capture under dry conditions, their affinity for water (H2O) mitigates their carbon capture performance in humid conditions. Herein, we report on the co‐adsorption of H2O and CO2 by TIFSIX‐3‐Ni—a high CO2 affinity HUM—and find that slow H2O sorption kinetics can enable CO2 uptake and release using shortened adsorption cycles with retention of ca. 90 % of dry CO2 uptake. Insight into co‐adsorption is provided by in situ infrared spectroscopy and ab initio calculations. The binding sites and sorption mechanisms reveal that both CO2 and H2O molecules occupy the same ultramicropore through favorable interactions between CO2 and H2O at low water loading. An energetically favored water network displaces CO2 molecules at higher loading. Our results offer bottom‐up design principles and insight into co‐adsorption of CO2 and H2O that is likely to be relevant across the full spectrum of carbon capture sorbents to better understand and address the challenge posed by humidity to gas capture.

Synergistic binding sites in a hybrid ultramicroporous material for one-step ethylene purification from ternary C2 hydrocarbon mixtures.

One-step separation of C2H4 from ternary C2H2/C2H4/C2H6 hydrocarbon mixtures is of great significance in the industry but is challenging due to the similar sizes and physical properties of C2H2, C2H4, and C2H6. Here, we report an anion-pillared hybrid ultramicroporous material, CuTiF6-TPPY, that has the ability of selective recognition of C2H4 over C2H2 and C2H6. The 4,6-connected fsc framework of CuTiF6-TPPY exhibits semi–cage-like one-dimensional channels sustained by porphyrin rings and TiF62− pillars, which demonstrates the noticeably enhanced adsorption of C2H2 and C2H6 over C2H4. Dynamic breakthrough experiments confirm the direct and facile high-purity C2H4 (>99.9%) production from a ternary gas mixture of C2H2/C2H6/C2H4 (1/9/90, v/v/v) under ambient conditions. Computational studies and in situ infrared reveal that the porphyrin moieties with large π-surfaces form multiple van der Waals interactions with C2H6; meanwhile, the polar TiF62− pillars form C–H•••F hydrogen bonding with C2H2. In contrast, the recognition sites for C2H4 in the framework are less marked.

The First Sulfate-Pillared Hybrid Ultramicroporous Material, SOFOUR-1-Zn, and Its Acetylene Capture Properties.

Hybrid ultramicroporous materials, HUMs, are comprised of metal cations linked by combinations of inorganic and organic ligands. Their modular nature makes them amenable to crystal engineering studies, which have thus far afforded four HUM platforms (as classified by the inorganic linkers). HUMs are of practical interest because of their benchmark gas separation performance for several industrial gas mixtures. We report herein design and gram‐scale synthesis of the prototypal sulfate‐linked HUM, the fsc topology coordination network ([Zn(tepb)(SO4)] n ), SOFOUR‐1‐Zn, tepb=(tetra(4‐pyridyl)benzene). Alignment of the sulfate anions enables strong binding to C2H2 via O⋅⋅⋅HC interactions but weak CO2 binding, affording a new benchmark for the difference between C2H2 and CO2 heats of sorption at low loading (ΔQ st=24 kJ mol−1). Dynamic column breakthrough studies afforded fuel‐grade C2H2 from trace (1 : 99) or 1 : 1 C2H2/CO2 mixtures, outperforming its SiF6 2− analogue, SIFSIX‐22‐Zn.

The First Sulfate‐Pillared Hybrid Ultramicroporous Material, SOFOUR‐1‐Zn, and Its Acetylene Capture Properties

AbstractHybrid ultramicroporous materials, HUMs, are comprised of metal cations linked by combinations of inorganic and organic ligands. Their modular nature makes them amenable to crystal engineering studies, which have thus far afforded four HUM platforms (as classified by the inorganic linkers). HUMs are of practical interest because of their benchmark gas separation performance for several industrial gas mixtures. We report herein design and gram‐scale synthesis of the prototypal sulfate‐linked HUM, the fsc topology coordination network ([Zn(tepb)(SO4)]n), SOFOUR‐1‐Zn, tepb=(tetra(4‐pyridyl)benzene). Alignment of the sulfate anions enables strong binding to C2H2 via O⋅⋅⋅HC interactions but weak CO2 binding, affording a new benchmark for the difference between C2H2 and CO2 heats of sorption at low loading (ΔQst=24 kJ mol−1). Dynamic column breakthrough studies afforded fuel‐grade C2H2 from trace (1 : 99) or 1 : 1 C2H2/CO2 mixtures, outperforming its SiF62− analogue, SIFSIX‐22‐Zn.

Crystal engineered hybrid ultramicroporous materials for single-step ethylene purification from C2–CO2 ternary mixture

Crystal engineered hybrid ultramicroporous materials for single-step ethylene purification from C₂–CO₂ ternary mixture

Breaking the trade-off between selectivity and adsorption capacity for gas separation

SummaryThe trade-off between selectivity and adsorption capacity with porous materials is a major roadblock to reducing the energy footprint of gas separation technologies. To address this matter, we report herein a systematic crystal engineering study of C2H2 removal from CO2 in a family of hybrid ultramicroporous materials (HUMs). The HUMs are composed of the same organic linker ligand, 4-(3,5-dimethyl-1H-pyrazol-4-yl)pyridine, pypz, three inorganic pillar ligands, and two metal cations, thereby affording six isostructural pcu topology HUMs. All six HUMs exhibited strong binding sites for C2H2 and weaker affinity for CO2. The tuning of pore size and chemistry enabled by crystal engineering resulted in benchmark C2H2/CO2 separation performance. Fixed-bed dynamic column breakthrough experiments for an equimolar (v/v = 1:1) C2H2/CO2 binary gas mixture revealed that one sorbent, SIFSIX-21-Ni, was the first C2H2 selective sorbent that combines exceptional separation selectivity (27.7) with high adsorption capacity (4 mmol·g−1).

Benchmark Acetylene Binding Affinity and Separation through Induced Fit in a Flexible Hybrid Ultramicroporous Material

AbstractStructural changes at the active site of an enzyme induced by binding to a substrate molecule can result in enhanced activity in biological systems. Herein, we report that the new hybrid ultramicroporous material sql‐SIFSIX‐bpe‐Zn exhibits an induced fit binding mechanism when exposed to acetylene, C2H2. The resulting phase change affords exceptionally strong C2H2 binding that in turn enables highly selective C2H2/C2H4 and C2H2/CO2 separation demonstrated by dynamic breakthrough experiments. sql‐SIFSIX‐bpe‐Zn was observed to exhibit at least four phases: as‐synthesised (α); activated (β); and C2H2 induced phases (β′ and γ). sql‐SIFSIX‐bpe‐Zn‐β exhibited strong affinity for C2H2 at ambient conditions as demonstrated by benchmark isosteric heat of adsorption (Qst) of 67.5 kJ mol−1 validated through in situ pressure gradient differential scanning calorimetry (PG‐DSC). Further, in situ characterisation and DFT calculations provide insight into the mechanism of the C2H2 induced fit transformation, binding positions and the nature of host‐guest and guest‐guest interactions.

Benchmark Acetylene Binding Affinity and Separation through Induced Fit in a Flexible Hybrid Ultramicroporous Material.

Structural changes at the active site of an enzyme induced by binding to a substrate molecule can result in enhanced activity in biological systems. Herein, we report that the new hybrid ultramicroporous material sql‐SIFSIX‐bpe‐Zn exhibits an induced fit binding mechanism when exposed to acetylene, C2H2. The resulting phase change affords exceptionally strong C2H2 binding that in turn enables highly selective C2H2/C2H4 and C2H2/CO2 separation demonstrated by dynamic breakthrough experiments. sql‐SIFSIX‐bpe‐Zn was observed to exhibit at least four phases: as‐synthesised (α); activated (β); and C2H2 induced phases (β′ and γ). sql‐SIFSIX‐bpe‐Zn‐β exhibited strong affinity for C2H2 at ambient conditions as demonstrated by benchmark isosteric heat of adsorption (Q st) of 67.5 kJ mol−1 validated through in situ pressure gradient differential scanning calorimetry (PG‐DSC). Further, in situ characterisation and DFT calculations provide insight into the mechanism of the C2H2 induced fit transformation, binding positions and the nature of host‐guest and guest‐guest interactions.