1
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Farhadi Jahromi B, Schmid R. Dielectric response of metal-organic frameworks as a function of confined guest species investigated by molecular dynamics simulations. J Chem Phys 2024; 160:184119. [PMID: 38738610 DOI: 10.1063/5.0203820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Accepted: 04/25/2024] [Indexed: 05/14/2024] Open
Abstract
When using metal-organic frameworks (MOFs) as electric field-dependent sensor devices, understanding their dielectric response is crucial as the orientation of polar groups is largely affected by confinement. To shed light on this at the molecular level, the response to a static field was computationally investigated for two structurally related MOFs, depending on their loading with guest molecules. The pillared-layer MOFs differ in their pillar moiety, with one bearing a rotatable permanent dipole moment and the other being non-polar. Two guest molecules with and without polarity, namely, methanol and methane, were considered. A comprehensive picture of the response of the guest molecules could be achieved with respect to both the amount and polarity of the confined species. For both MOFs, the dielectric response is very sensitive to the introduction of methanol, showing an anisotropic and non-linear increase in the system's relative permittivity expressed by a strongly increasing polarization response to external electric fields scaling with the number of confined methanol molecules. As expected, the effect of methane in the non-dipolar MOF is negligible, whereas subtle differences can be observed for the dipolar response of the MOF with rotatable dipolar linker groups. Taking advantage of these anisotropic and guest-molecule-specific confinement effects may open pathways for future sensing applications. Finally, methanol-induced global framework dynamics were observed in both MOFs.
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Affiliation(s)
- Babak Farhadi Jahromi
- Computational Materials Chemistry Group, Lehrstuhl für Anorganische Chemie 2, Ruhr-Universität Bochum, Bochum, Germany
| | - Rochus Schmid
- Computational Materials Chemistry Group, Lehrstuhl für Anorganische Chemie 2, Ruhr-Universität Bochum, Bochum, Germany
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2
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Stracke K, Evans JD. The use of collective variables and enhanced sampling in the simulations of existing and emerging microporous materials. NANOSCALE 2024. [PMID: 38647659 DOI: 10.1039/d4nr01024h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
Microporous materials, including zeolites, metal-organic frameworks, and cage compounds, offer diverse functionalities due to their unique dynamics and guest confinement properties. These materials play a significant role in separation, catalysis, and sensing, but their complexity hinders exploration using traditional atomistic simulations. This review explores collective variables (CVs) paired with enhanced sampling as a powerful approach to enable efficient investigation of key features in microporous materials. We highlight successful applications of CVs in studying adsorption, diffusion, phase transitions, and mechanical properties, demonstrating their crucial role in guiding material design and optimisation. The future of CVs lies in integration with techniques like machine learning, allowing for enhanced efficiency and accuracy. By tailoring CVs to specific materials and developing multi-scale approaches we can further unlock the intricacies of these fascinating materials. Simulations are a cornerstone in unravelling the complexities of microporous materials and are crucial for our future understanding.
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Affiliation(s)
- Konstantin Stracke
- School of Physics, Chemistry and Earth Science, The University of Adelaide, 5005 Australia.
| | - Jack D Evans
- School of Physics, Chemistry and Earth Science, The University of Adelaide, 5005 Australia.
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3
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Rams-Baron M, Błażytko A, Książek M, Kusz J, Paluch M. Internal Secondary Relaxation as a Dielectric Probe of Molecular Surroundings. J Phys Chem Lett 2024; 15:2595-2600. [PMID: 38416777 PMCID: PMC10926159 DOI: 10.1021/acs.jpclett.4c00128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2024]
Abstract
We investigated the secondary relaxation behavior in rotor molecules in a glassy and crystalline state by using the dielectric method. Without changing the molecular source of secondary relaxation, only by modifying the environment around the rotating unit we observed notable variations in spectral parameters. Our results show that internal rotation, like a probe, can sample the immediate surroundings with high sensitivity to molecular-level changes that impact the rotation parameters. Our research offers a new perspective on the dielectric behavior of internal secondary relaxations and challenges the paradigm of their irrelevant nature.
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Affiliation(s)
- Marzena Rams-Baron
- August Chelkowski Institute of Physics, University of Silesia in Katowice, 75 Pulku Piechoty 1, 41-500 Chorzow, Poland
| | - Alfred Błażytko
- August Chelkowski Institute of Physics, University of Silesia in Katowice, 75 Pulku Piechoty 1, 41-500 Chorzow, Poland
| | - Maria Książek
- August Chelkowski Institute of Physics, University of Silesia in Katowice, 75 Pulku Piechoty 1, 41-500 Chorzow, Poland
| | - Joachim Kusz
- August Chelkowski Institute of Physics, University of Silesia in Katowice, 75 Pulku Piechoty 1, 41-500 Chorzow, Poland
| | - Marian Paluch
- August Chelkowski Institute of Physics, University of Silesia in Katowice, 75 Pulku Piechoty 1, 41-500 Chorzow, Poland
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4
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Li W, Xie M, Zhang SY, Zeng CH, Du ZY, He CT. A confinement-regulated (H 3C-NH 3) + ion as a smallest dual-wheel rotator showing bisected rotation dynamics. Phys Chem Chem Phys 2024; 26:7269-7275. [PMID: 38193864 DOI: 10.1039/d3cp05406c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2024]
Abstract
On the basis of variable-temperature single-crystal X-ray diffraction, rotational energy barrier analysis, variable-temperature/frequency dielectric response, and molecular dynamics simulations, here we report a new crystalline supramolecular rotor (CH3NH3)(18-crown-6)[CuCl3], in which the (H3C-NH3)+ ion functions as a smallest dual-wheel rotator showing bisected rotation dynamics, while the host 18-crown-6 macrocycle behaves as a stator that is not strictly stationary. This study also provides a helpful insight into the dynamics of ubiquitous -CH3/-NH3 groups confined in organic or organic-inorganic hybrid solids.
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Affiliation(s)
- Wang Li
- College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, China.
- College of Chemistry and Chemical Engineering, Gannan Normal University, Ganzhou 341000, China
| | - Miao Xie
- College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, China.
| | - Shi-Yong Zhang
- College of Chemistry and Chemical Engineering, Gannan Normal University, Ganzhou 341000, China
| | - Cheng-Hui Zeng
- College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, China.
- School of Chemistry, Sun Yat-Sen University, Guangzhou 510275, China
| | - Zi-Yi Du
- College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, China.
| | - Chun-Ting He
- College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, China.
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5
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Xiao H, Hu WY, Wang Q, Zeng CH, Li HH, Liu H, Du ZY, He CT. Molecular rotators anchored on a rod-like anionic coordination polymer adhered by charge-assisted hydrogen bonds. Phys Chem Chem Phys 2024; 26:3974-3980. [PMID: 38221866 DOI: 10.1039/d3cp05597c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2024]
Abstract
On the basis of variable-temperature single-crystal X-ray diffraction, variable-temperature/frequency dielectric analysis, variable-temperature solid-state nuclear magnetic resonance spectroscopy, and molecular dynamics simulations, here we present a new model of crystalline supramolecular rotor (i-PrNHMe2)[CdBr3], where a conformationally flexible near-spherical (i-PrNHMe2)+ cation functions as a rotator and a rod-like anionic coordination polymer {[CdBr3]-}∞ acts as the stator, and the adhesion of them is realized by charge-assisted hydrogen bonds.
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Affiliation(s)
- Hui Xiao
- College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, China.
| | - Wei-Yu Hu
- College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, China.
| | - Qing Wang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Cheng-Hui Zeng
- College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, China.
| | - Hao-Hong Li
- College of Chemistry, Fuzhou University, Fuzhou 350108, China
| | - Haiming Liu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Zi-Yi Du
- College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, China.
| | - Chun-Ting He
- College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, China.
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6
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Jin M, Kitsu R, Hammyo N, Sato-Tomita A, Mizuno M, Mikherdov AS, Tsitsvero M, Lyalin A, Taketsugu T, Ito H. A Steric-Repulsion-Driven Clutch Stack of Triaryltriazines: Correlated Molecular Rotations and a Thermoresponsive Gearshift in the Crystalline Solid. J Am Chem Soc 2023; 145:27512-27520. [PMID: 38060534 DOI: 10.1021/jacs.3c08909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
We report that a newly developed type of triaryltriazine rotor, which bears bulky silyl moieties on the para position of its peripheral phenylene groups, forms a columnar stacked clutch structure in the crystalline phase. The phenylene units of the crystalline rotors display two different and interconvertible correlated molecular motions. It is possible to switch between these intermolecular geared rotational motions via a thermally induced crystal-to-crystal phase transition. Variable-temperature solid-state 2H NMR measurements and X-ray diffraction studies revealed that the crystalline rotor is characterized by a vertically stacked columnar structure upon introducing a bulky Si moiety with bent geometry as the stator. The structure exhibits correlated flapping motions via a combination of 85° and ca. 95° rotations between 295 and 348 K, concurrent with a negative entropy change (ΔS‡ = -23 ± 0.3 cal mol-1 K-1). Interestingly, heating the crystal beyond 348 K induces an anisotropic expansion of the column and lowers the steric congestion between the adjacent rotators, thus altering the correlated motions from a flapping motion to a correlated 2-fold 180° rotation with a lower entropic penalty (ΔS‡ = -14 ± 0.5 cal mol-1 K-1). The obtained results of our study suggest that the intermolecular stacking of the C3-symmetric rotator driven by the steric repulsion of the bulky stator represents a promising strategy for producing various correlated molecular motions in the crystalline phase. Moreover, direct and reversible modulation of the intermolecularly correlated rotation is achieved via a thermally induced crystal-to-crystal phase transition, which operates as a gearshift function at the molecular level.
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Affiliation(s)
- Mingoo Jin
- Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, Sapporo, Hokkaido 060-8628, Japan
| | - Ryunosuke Kitsu
- Division of Applied Chemistry and Frontier Chemistry Center (FCC), Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628, Japan
| | - Natsumi Hammyo
- Division of Applied Chemistry and Frontier Chemistry Center (FCC), Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628, Japan
| | - Ayana Sato-Tomita
- Division of Biophysics, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan
| | - Motohiro Mizuno
- Division of Material Chemistry, Graduate School of Natural Science and Technology, Nanomaterials Research Institute, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Alexander S Mikherdov
- Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, Sapporo, Hokkaido 060-8628, Japan
| | - Mikhail Tsitsvero
- Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, Sapporo, Hokkaido 060-8628, Japan
| | - Andrey Lyalin
- Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, Sapporo, Hokkaido 060-8628, Japan
- Research Center for Energy and Environmental Materials (GREEN), National Institute for Materials Science, Namiki 1-1, Tsukuba 305-0044, Japan
| | - Tetsuya Taketsugu
- Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, Sapporo, Hokkaido 060-8628, Japan
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan
| | - Hajime Ito
- Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, Sapporo, Hokkaido 060-8628, Japan
- Division of Applied Chemistry and Frontier Chemistry Center (FCC), Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628, Japan
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7
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Gunaga SS, Bryce DL. Modulation of Rotational Dynamics in Halogen-Bonded Cocrystalline Solids. J Am Chem Soc 2023; 145:19005-19017. [PMID: 37586107 DOI: 10.1021/jacs.3c06343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/18/2023]
Abstract
Dynamic processes are responsible for the functionality of a range of materials, biomolecules, and catalysts. We report a detailed systematic study of the modulation of methyl rotational dynamics via the direct and the indirect influence of noncovalent halogen bonds. For this purpose, a novel series of cocrystalline architectures featuring halogen bonds (XB) to tetramethylpyrazine (TMP) is designed and prepared using gas-phase, solution, and solid-state mechanochemical methods. Single-crystal X-ray diffraction reveals the capacity of molecular bromine as well as weak chloro-XB donors to act as robust directional structure-directing elements. Methyl rotational barriers (Ea) measured using variable-temperature deuterium solid-state NMR range from 3.75 ± 0.04 kJ mol-1 in 1,3,5-trichloro-2,4,6-trifluorobenzene·TMP to 7.08 ± 0.15 kJ mol-1 in 1,4-dichlorotetrafluorobenzene·TMP. Ea data for a larger series of TMP cocrystals featuring chloro-, bromo-, and iodo-XB donors are shown to be governed by a combination of steric and electronic factors. The average number of carbon-carbon close contacts to the methyl group is found to be a key steric metric capable of rationalizing the observed trends within each of the Cl, Br, and I series. Differences between each series are accounted for by considering the strength of the σ-hole on the XB donor. One possible route to modulating dynamics is therefore via designer cocrystals of variable stoichiometry, maintaining the core chemical features of interest between a given donor and acceptor while simultaneously modifying the number of carbon close contacts affecting dynamics. These principles may provide design opportunities to modulate more complex geared or cascade dynamics involving larger functional groups.
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Affiliation(s)
- Shubha S Gunaga
- Department of Chemistry and Biomolecular Sciences, Centre for Catalysis Research and Innovation, and Nexus for Quantum Technologies, University of Ottawa, 10 Marie Curie Private, Ottawa, Ontario K1N 6N5 Canada
| | - David L Bryce
- Department of Chemistry and Biomolecular Sciences, Centre for Catalysis Research and Innovation, and Nexus for Quantum Technologies, University of Ottawa, 10 Marie Curie Private, Ottawa, Ontario K1N 6N5 Canada
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8
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Schnabel J, Schulz A, Lunkenheimer P, Volkmer D. Benzothiadiazole-based rotation and possible antipolar order in carboxylate-based metal-organic frameworks. Commun Chem 2023; 6:161. [PMID: 37516750 PMCID: PMC10387106 DOI: 10.1038/s42004-023-00959-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 07/14/2023] [Indexed: 07/31/2023] Open
Abstract
By modifying organic ligands of metal-organic framework with dipolar units, they turn suitable for various applications, e.g., in the field of sensor systems or switching of gas permeation. Dipolar linkers in the organic ligand are capable to rotate in certain temperature and frequency ranges. The copper-bearing paddlewheel shaped metal-organic frameworks ZJNU-40 and JLU-Liu30 possess such a polarizable dipole moment due to their benzothiadiazole moiety in the organic ligands. Here, we investigate the molecular rotor behavior of benzothiadiazole units of the two carboxylate-based MOFs by dielectric spectroscopy and computational simulation. Our dielectric results provide clear evidence for significant reorientational relaxation dynamics of these rotors, revealing various characteristics of glasslike freezing upon cooling. The calculated rotational energy barriers are consistent with experimentally determined barriers for single-dipole dynamics. Moreover, for JLU-Liu30 we find hints at antipolar ordering below about 300 K.
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Affiliation(s)
- Jennifer Schnabel
- Chair of Solid State and Materials Chemistry, University of Augsburg, Institute of Physics, Universitaetsstrasse 1, 86159, Augsburg, Germany
| | - Arthur Schulz
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, Institute of Physics, Universitaetsstrasse 1, 86159, Augsburg, Germany
| | - Peter Lunkenheimer
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, Institute of Physics, Universitaetsstrasse 1, 86159, Augsburg, Germany
| | - Dirk Volkmer
- Chair of Solid State and Materials Chemistry, University of Augsburg, Institute of Physics, Universitaetsstrasse 1, 86159, Augsburg, Germany.
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9
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Krause S, Milić JV. Functional dynamics in framework materials. Commun Chem 2023; 6:151. [PMID: 37452112 PMCID: PMC10349092 DOI: 10.1038/s42004-023-00945-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 06/29/2023] [Indexed: 07/18/2023] Open
Abstract
Dynamic crystalline materials have emerged as a unique category of condensed phase matter that combines crystalline lattice with components that display dynamic behavior in the solid state. This has involved a range of materials incorporating dynamic functional units in the form of stimuli-responsive molecular switches and machines, among others. In particular, it has been possible by relying on framework materials, such as porous molecular frameworks and other hybrid organic-inorganic systems that demonstrated potential for serving as scaffolds for dynamic molecular functions. As functional dynamics increase the level of complexity, the associated phenomena are often overlooked and need to be explored. In this perspective, we discuss a selection of recent developments of dynamic solid-state materials across material classes, outlining opportunities and fundamental and methodological challenges for their advancement toward innovative functionality and applications.
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Affiliation(s)
- Simon Krause
- Max Planck Institute for Solid-State Research, Stuttgart, Germany.
| | - Jovana V Milić
- Adolphe Merkle Institute, University of Fribourg, Fribourg, Switzerland.
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10
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Li B, Vizuet JP, McCandless GT, Balkus Jr KJ. Controlling Pore Size and Interlayer Space by Ring Rotation and Electron-Withdrawing Effects in a 2D MOF. Polyhedron 2022. [DOI: 10.1016/j.poly.2022.116211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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11
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Li X, Xie J, Du Z, Jiang L, Li G, Ling S, Zhu K. Docking rings in a solid: reversible assembling of pseudorotaxanes inside a zirconium metal-organic framework. Chem Sci 2022; 13:6291-6296. [PMID: 35733896 PMCID: PMC9159108 DOI: 10.1039/d2sc01497a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 04/26/2022] [Indexed: 11/22/2022] Open
Abstract
An unprecedented zirconium metal–organic framework featuring a T-shaped benzimidazole strut was constructed and employed as a sponge-like material for selective absorption of macrocyclic guests. The neutral benzimidazole domain of the as-synthesized framework can be readily protonated and fully converted to benzimidazolium. Mechanical threading of [24]crown-8 ether wheels onto recognition sites to form pseudorotaxanes was evidenced by solution nuclear magnetic resonance, solid-state fluorescence, and infrared spectroscopy. Selective absorption of [24]crown-8 ether rather than its dibenzo counterpart was also observed. Further study reveals that this binding process is reversible and acid–base switchable. The success of docking macrocyclic guests in crystals via host–guest interactions provides an alternative route to complex functional materials with interpenetrated structures. A T-shaped ligand was designed as struts for building a zirconium metal–organic framework. Acid–base switchable docking and releasing a 24-membered crown ether inside crystals was successfully accomplished via post-synthetic modification.![]()
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Affiliation(s)
- Xia Li
- School of Chemistry, Sun Yat-Sen University Guangzhou 510275 China
| | - Jialin Xie
- School of Chemistry, Sun Yat-Sen University Guangzhou 510275 China
| | - Zhenglin Du
- School of Chemistry, Sun Yat-Sen University Guangzhou 510275 China
| | - Long Jiang
- Instrumental Analysis and Research Centre, Sun Yat-Sen University Guangzhou 510275 China
| | - Guangqin Li
- School of Chemistry, Sun Yat-Sen University Guangzhou 510275 China
| | - Sanliang Ling
- Advanced Materials Research Group, Faculty of Engineering, University of Nottingham Nottingham NG7 2RD UK
| | - Kelong Zhu
- School of Chemistry, Sun Yat-Sen University Guangzhou 510275 China
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12
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Li W, Liu D, Hu W, Liu Q, Du Z, He C, Zhang W, Chen X. A Crystalline Supramolecular Rotor Functioned by Dual Ultrasmall Polar Rotators. CHINESE J CHEM 2022. [DOI: 10.1002/cjoc.202200212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Wang Li
- College of Chemistry and Chemical Engineering, MOE Key Laboratory of Fluorine and Silicon for Energy Materials and Chemistry Jiangxi Normal University Nanchang 330022 China
| | - De‐Xuan Liu
- School of Chemistry, MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, Sun Yat‐Sen University Guangzhou 510275 China
| | - Wei‐Yu Hu
- College of Chemistry and Chemical Engineering, MOE Key Laboratory of Fluorine and Silicon for Energy Materials and Chemistry Jiangxi Normal University Nanchang 330022 China
| | - Qing‐Yan Liu
- College of Chemistry and Chemical Engineering, MOE Key Laboratory of Fluorine and Silicon for Energy Materials and Chemistry Jiangxi Normal University Nanchang 330022 China
| | - Zi‐Yi Du
- College of Chemistry and Chemical Engineering, MOE Key Laboratory of Fluorine and Silicon for Energy Materials and Chemistry Jiangxi Normal University Nanchang 330022 China
| | - Chun‐Ting He
- College of Chemistry and Chemical Engineering, MOE Key Laboratory of Fluorine and Silicon for Energy Materials and Chemistry Jiangxi Normal University Nanchang 330022 China
| | - Wei‐Xiong Zhang
- School of Chemistry, MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, Sun Yat‐Sen University Guangzhou 510275 China
| | - Xiao‐Ming Chen
- School of Chemistry, MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, Sun Yat‐Sen University Guangzhou 510275 China
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13
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Amombo Noa FM, Grape ES, Åhlén M, Reinholdsson WE, Göb CR, Coudert FX, Cheung O, Inge AK, Öhrström L. Chiral Lanthanum Metal-Organic Framework with Gated CO 2 Sorption and Concerted Framework Flexibility. J Am Chem Soc 2022; 144:8725-8733. [PMID: 35503249 PMCID: PMC9122260 DOI: 10.1021/jacs.2c02351] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
![]()
A metal–organic
framework (MOF) CTH-17 based
on lanthanum(III) and the conformationally chiral linker 1,2,3,4,5,6-hexakis(4-carboxyphenyl)benzene,
cpb6–: [La2(cpb)]·1.5dmf was prepared
by the solvothermal method in dimethylformamide (dmf) and characterized
by variable-temperature X-ray powder diffraction (VTPXRD), variable-temperature
X-ray single-crystal diffraction (SCXRD), and thermogravimetric analysis
(TGA). CTH-17 is a rod-MOF with new topology och. It has high-temperature stability with Sohncke space groups P6122/P6522 at 90
K and P622 at 300 and 500 K, all phases characterized
with SCXRD and at 293 K also with three-dimensional (3D) electron
diffraction. VTPXRD indicates a third phase appearing after 620 K
and stable up to 770 K. Gas sorption isotherms with N2 indicate
a modest surface area of 231 m2 g–1 for CTH-17, roughly in agreement with the crystal structure. Carbon
dioxide sorption reveals a gate-opening effect of CTH-17 where the structure opens up when the loading of CO2 reaches
approximately ∼0.45 mmol g–1 or 1 molecule
per unit cell. Based on the SCXRD data, this is interpreted as flexibility
based on the concerted movements of the propeller-like hexatopic cpb
linkers, the movement intramolecularly transmitted by the π–π
stacking of the cpb linkers and helped by the fluidity of the LaO6 coordination sphere. This was corroborated by density functional
theory (DFT) calculations yielding the chiral phase (P622) as the energy minimum and a completely racemic phase (P6/mmm), with symmetric cpb linkers representing
a saddle point in a racemization process.
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Affiliation(s)
- Francoise M Amombo Noa
- Chemistry and Biochemistry, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
| | - Erik Svensson Grape
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm SE-10691, Sweden
| | - Michelle Åhlén
- Nanotechnology and Functional Materials, Department of Material Sciences and Engineering, Uppsala University, SE-751 21 Uppsala, Sweden
| | - William E Reinholdsson
- Chemistry and Biochemistry, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
| | - Christian R Göb
- Rigaku Europe SE, Hugenottenallee 167, Neu-Isenburg D-63263, Germany
| | - François-Xavier Coudert
- Chimie ParisTech, PSL University, CNRS, Institut de Recherche de Chimie Paris, 75005 Paris, France
| | - Ocean Cheung
- Nanotechnology and Functional Materials, Department of Material Sciences and Engineering, Uppsala University, SE-751 21 Uppsala, Sweden
| | - A Ken Inge
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm SE-10691, Sweden
| | - Lars Öhrström
- Chemistry and Biochemistry, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
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14
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Altenhof AR, Gan Z, Schurko RW. Reducing the effects of weak homonuclear dipolar coupling with CPMG pulse sequences for static and spinning solids. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2022; 337:107174. [PMID: 35279507 DOI: 10.1016/j.jmr.2022.107174] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 02/18/2022] [Accepted: 02/21/2022] [Indexed: 06/14/2023]
Abstract
The Carr-Purcell/Meiboom-Gill (CPMG) pulse sequence, initially introduced for measuring transverse relaxation time constants (T2), can provide significant signal enhancements for solid-state NMR (SSNMR) spectra. The proper implementation of CPMG for acquiring spectra influenced by chemical shift anisotropies (CSAs), first and/or second order quadrupolar interactions, or paramagnetic broadening has been well documented to date, as have the effects of heteronuclear dipolar coupling on CPMG echo trains and T2 lifetimes. Homonuclear dipolar coupling can also impact T2 lifetimes and CPMG echo trains; these effects have been thoroughly investigated for spectra of homonuclear dipolar coupled spin-1/2 nuclei typically acquired under static conditions that are predominantly influenced by dipolar broadening (e.g., 1H, 19F, etc.). In particular, it has been shown that short refocusing pulses with small flip angles can extend the effective T2 (T2eff, the observed T2 constant as impacted by experimental conditions) measured by CPMG sequences for strong homonuclear dipolar coupled spin-1/2 pairs under static conditions. To date, these effects have not been explored for (i) spin-1/2 nuclei that have significant CSAs and simultaneously feature weak homonuclear dipolar couplings, (ii) for quadrupolar nuclei that are also weakly homonuclear dipolar coupled, and (iii) for either of these cases under magic-angle spinning (MAS) conditions. Herein, we demonstrate that short refocusing pulses that cause small flip angles can reduce the attenuation of signal in CPMG echo trains resulting from dipolar dephasing caused by the weak homonuclear dipolar couplings. For both spin-1/2 and quadrupolar nuclei, this can lead to significant extensions in T2eff and signal enhancements of up to three times compared to conventional CPMG in favourable cases. These phenomena can occur under both static and magic-angle spinning (MAS) conditions, in the latter of which homonuclear couplings are reintroduced by rotational resonance (R2) recoupling. Experimental examples of 13C (I = 1/2), 2H (I = 1), 87Rb (I = 3/2), 23Na (I = 3/2), and 35Cl (I = 3/2) NMR under static and MAS conditions, as well as simulations of these phenomena, are shown and discussed.
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Affiliation(s)
- Adam R Altenhof
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA; National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, FL 32310, USA
| | - Zhehong Gan
- National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, FL 32310, USA
| | - Robert W Schurko
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA; National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, FL 32310, USA.
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