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Beckmann PA, Rablen PR, Schmink J, Szewczyk ST, Rheingold AL. Concomitant Polymorphism in an Organic Solid: Molecular and Crystal Structure and Intra- and Intermolecular Potential Contributions to tert-Butyl and Methyl Group Rotation. Chemphyschem 2019; 20:2887-2894. [PMID: 31507058 DOI: 10.1002/cphc.201900436] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 09/09/2019] [Indexed: 11/07/2022]
Abstract
We investigate the relationship between structure (crystal and molecular) and tert-butyl and methyl group dynamics in 2-(tert-butyl)-9-(4-(tert-butyl)phenyl)anthracene. Powder and single-crystal X-ray diffraction, taken together, show that different polycrystalline samples recrystallized from different solvents have different amounts of at least four polymorphs (crystallites having different crystal structures), of which we have identified three by single crystal X-ray diffraction. The molecules in the asymmetric units of the different crystal structures differ by the dihedral angle the tert-butylphenyl group makes with the anthracene moiety. Ab initio electronic structure calculations on the isolated molecule show that very little intramolecular energy is required to change this angle over a range of about 60° which is probably the origin of the concomitant polymorphism (crystals of more than one polymorph in a polycrystalline sample). Solid state 1 H nuclear magnetic resonance (NMR) spin-lattice relaxation experiments support the powder and single-crystal X-ray results and provide average NMR activation energies (closely related to rotational barriers) for the rotation of the tert-butyl groups and their constituent methyl groups. These barriers have both an intramolecular and an intermolecular component. The latter is sensitive to the crystal structure. The intramolecular components of the rotational barriers of the two tert-butyl groups in the isolated molecule are investigated with ab initio electronic structure calculations.
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Affiliation(s)
- Peter A Beckmann
- Department of Physics, Bryn Mawr College, Bryn Mawr, Pennsylvania, USA
| | - Paul R Rablen
- Department of Chemistry and Biochemistry, Swarthmore College, Swarthmore, Pennsylvania, USA
| | - Jason Schmink
- Division of General Education, Pennsylvania College of Health Sciences, Lancaster, Pennsylvania, USA
| | - Steven T Szewczyk
- Department of Materials Science and Engineering School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Arnold L Rheingold
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, USA
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2
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Beckmann P. Solid state proton spin-lattice relaxation in polycrystalline methylphenanthrenes. IV. 1,4-dimethylphenanthrene. J Chem Phys 2019; 150:124508. [DOI: 10.1063/1.5082925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Peter Beckmann
- Department of Physics, Bryn Mawr College, 101 N. Merion Avenue, Bryn Mawr, Pennsylvania 19010, USA
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Szell PMJ, Zablotny S, Bryce DL. Halogen bonding as a supramolecular dynamics catalyst. Nat Commun 2019; 10:916. [PMID: 30796220 PMCID: PMC6385366 DOI: 10.1038/s41467-019-08878-8] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 02/04/2019] [Indexed: 01/23/2023] Open
Abstract
Dynamic processes have many implications in functional molecules, including catalysts, enzymes, host-guest complexes, and molecular machines. Here, we demonstrate via deuterium NMR relaxation experiments how halogen bonding directly impacts the dynamics in solid 2,3,5,6-tetramethylpyrazine cocrystals, catalyzing the methyl group rotation. On average, we observe a reduction of 56% in the rotational activation energy of the methyl groups in the halogen bonded cocrystals, contrasting the reduction of 36% in the hydrogen bonded cocrystals, with respect to pure 2,3,5,6-tetramethylpyrazine. Density functional theory calculations attribute this superior catalytic ability of the halogen bond to the simultaneous destabilization of the staggered conformation and stabilization of the gauche conformation, overall reducing the rotational energy barrier. Furthermore, the calculations suggest that the catalytic ability of the halogen bond may be tuneable, with stronger halogen bond donors acting as superior dynamics catalysts. Thus, halogen bonding may play a role in both assembly and promoting dynamical processes. The halogen bond is well known for its ability to assemble supramolecules. Here, using NMR experiments, the authors reveal the role of these bonds in dynamic processes, finding that the halogen bond directly catalyzes dynamical rotation in solid cocrystals by reducing the associated energy barrier.
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Affiliation(s)
- Patrick M J Szell
- Department of Chemistry and Biomolecular Sciences & Centre for Catalysis Research and Innovation, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
| | - Scott Zablotny
- Department of Chemistry and Biomolecular Sciences & Centre for Catalysis Research and Innovation, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
| | - David L Bryce
- Department of Chemistry and Biomolecular Sciences & Centre for Catalysis Research and Innovation, University of Ottawa, Ottawa, ON, K1N 6N5, Canada.
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Beckmann PA, Ford J, Malachowski WP, McGhie AR, Moore CE, Rheingold AL, Sloan GJ, Szewczyk ST. Proton Spin-Lattice Relaxation in Organic Molecular Solids: Polymorphism and the Dependence on Sample Preparation. Chemphyschem 2018; 19:2423-2436. [PMID: 29956438 DOI: 10.1002/cphc.201800237] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2018] [Indexed: 11/07/2022]
Abstract
We report solid-state nuclear magnetic resonance 1 H spin-lattice relaxation, single-crystal X-ray diffraction, powder X-ray diffraction, field emission scanning electron microscopy, and differential scanning calorimetry in solid samples of 2-ethylanthracene (EA) and 2-ethylanthraquinone (EAQ) that have been physically purified in different ways from the same commercial starting compounds. The solid-state 1 H spin-lattice relaxation is always non-exponential at high temperatures as expected when CH3 rotation is responsible for the relaxation. The 1 H spin-lattice relaxation experiments are very sensitive to the "several-molecule" (clusters) structure of these van der Waals molecular solids. In the three differently prepared samples of EAQ, the relaxation also becomes very non-exponential at low temperatures. This is very unusual and the decay of the nuclear magnetization can be fitted with both a stretched exponential and a double exponential. This unusual result correlates with the powder X-ray diffractometry results and suggests that the anomalous relaxation is due to crystallites of two (or more) different polymorphs (concomitant polymorphism).
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Affiliation(s)
- Peter A Beckmann
- Department of Physics, Bryn Mawr College, Bryn Mawr, Pennsylvania, USA
| | - Jamie Ford
- Nanoscale Characterization Facility Singh Center for Nanotechnology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | | | - Andrew R McGhie
- Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Curtis E Moore
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, USA
| | - Arnold L Rheingold
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, USA
| | - Gilbert J Sloan
- Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Steven T Szewczyk
- Department of Materials Science and Engineering School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Pestryaev EM. Oscillating Free Induction Decay in Polymer Systems: Theoretical Analysis. POLYMER SCIENCE SERIES A 2018. [DOI: 10.1134/s0965545x18040090] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Beckmann PA, Bohen JM, Ford J, Malachowski WP, Mallory CW, Mallory FB, McGhie AR, Rheingold AL, Sloan GJ, Szewczyk ST, Wang X, Wheeler KA. Monitoring a simple hydrolysis process in an organic solid by observing methyl group rotation. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2017; 85-86:1-11. [PMID: 28260612 DOI: 10.1016/j.ssnmr.2017.01.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 12/26/2016] [Accepted: 01/24/2017] [Indexed: 06/06/2023]
Abstract
We report a variety of experiments and calculations and their interpretations regarding methyl group (CH3) rotation in samples of pure 3-methylglutaric anhydride (1), pure 3-methylglutaric acid (2), and samples where the anhydride is slowly absorbing water from the air and converting to the acid [C6H8O3(1) + H2O → C6H10O4(2)]. The techniques are solid state 1H nuclear magnetic resonance (NMR) spin-lattice relaxation, single-crystal X-ray diffraction, electronic structure calculations in both isolated molecules and in clusters of molecules that mimic the crystal structure, field emission scanning electron microscopy, differential scanning calorimetry, and high resolution 1H NMR spectroscopy. The solid state 1H spin-lattice relaxation experiments allow us to observe the temperature dependence of the parameters that characterize methyl group rotation in both compounds and in mixtures of the two compounds. In the mixtures, both types of methyl groups (that is, molecules of 1 and 2) can be observed independently and simultaneously at low temperatures because the solid state 1H spin-lattice relaxation is appropriately described by a double exponential. We have followed the conversion 1 → 2 over periods of two years. The solid state 1H spin-lattice relaxation experiments in pure samples of 1 and 2 indicate that there is a distribution of NMR activation energies for methyl group rotation in 1 but not in 2 and we are able to explain this in terms of the particle sizes seen in the field emission scanning electron microscopy images.
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Affiliation(s)
- Peter A Beckmann
- Department of Physics, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, PA 19010-2899, USA.
| | - Joseph M Bohen
- Department of Chemistry, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, PA 19010-2899, USA
| | - Jamie Ford
- Nanoscale Characterization Facility, Singh Center for Nanotechnology, University of Pennsylvania, 3205 Walnut St., Philadelphia, PA 19104-3405, USA
| | - William P Malachowski
- Department of Chemistry, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, PA 19010-2899, USA
| | - Clelia W Mallory
- Department of Chemistry, University of Pennsylvania, 231 South 34 Street, Philadelphia, PA 19104-6323, USA
| | - Frank B Mallory
- Department of Chemistry, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, PA 19010-2899, USA
| | - Andrew R McGhie
- Laboratory for Research on the Structure of Matter, University of Pennsylvania, 3231 Walnut St., Philadelphia, PA 19104-6202, USA
| | - Arnold L Rheingold
- Department of Chemistry and Biochemistry, University of California, San Diego, 5128 Urey Hall, 9500 Gilman Dr., La Jolla, CA 92093-0358, USA
| | - Gilbert J Sloan
- Laboratory for Research on the Structure of Matter, University of Pennsylvania, 3231 Walnut St., Philadelphia, PA 19104-6202, USA
| | - Steven T Szewczyk
- Department of Materials Science and Engineering, School of Engineering and Applied Science, University of Pennsylvania, 3231 Walnut St., Philadelphia, PA 19104-6202, USA
| | - Xianlong Wang
- Key Laboratory for NeuroInformation of Ministry of Education, School of Life Science and Technology, University of Electronic Science and Technology of China, 4 North Jianshe Rd., 22nd Section, Chengdu 610054, China
| | - Kraig A Wheeler
- Department of Chemistry, Eastern Illinois University, 600 Lincoln Ave., Charleston, IL 69120-3099, USA
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Beckmann PA, McGhie AR, Rheingold AL, Sloan GJ, Szewczyk ST. Solid-Solid Phase Transitions and tert-Butyl and Methyl Group Rotation in an Organic Solid: X-ray Diffractometry, Differential Scanning Calorimetry, and Solid-State 1H Nuclear Spin Relaxation. J Phys Chem A 2017; 121:6220-6230. [PMID: 28742961 DOI: 10.1021/acs.jpca.7b06265] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Using solid-state 1H nuclear magnetic resonance (NMR) spin-lattice relaxation experiments, we have investigated the effects of several solid-solid phase transitions on tert-butyl and methyl group rotation in solid 1,3,5-tri-tert-butylbenzene. The goal is to relate the dynamics of the tert-butyl groups and their constituent methyl groups to properties of the solid determined using single-crystal X-ray diffraction and differential scanning calorimetry (DSC). On cooling, the DSC experiments see a first-order, solid-solid phase transition at either 268 or 155 K (but not both) depending on thermal history. The 155 K transition (on cooling) is identified by single-crystal X-ray diffraction to be one from a monoclinic phase (above 155 K), where the tert-butyl groups are disordered (that is, with a rotational 6-fold intermolecular potential dominating), to a triclinic phase (below 155 K), where the tert-butyl groups are ordered (that is, with a rotational 3-fold intermolecular potential dominating). This transition shows very different DSC scans when both a 4.7 mg polycrystalline sample and a 19 mg powder sample are used. The 1H spin-lattice relaxation experiments with a much larger 0.7 g sample are very complicated and, depending on thermal history, can show hysteresis effects over many hours and over very large temperature ranges. In the high-temperature monoclinic phase, the tert-butyl groups rotate with NMR activation energies (closely related to rotational barriers) in the 17-23 kJ mol-1 range, and the constituent methyl groups rotate with NMR activation energies in the 7-12 kJ mol-1 range. In the low-temperature triclinic phase, the rotations of the tert-butyl groups and their methyl groups in the aromatic plane are quenched (on the NMR time scale). The two out-of-plane methyl groups in the tert-butyl groups are rotating with activation energies in the 5-11 kJ mol-1 range.
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Affiliation(s)
- Peter A Beckmann
- Department of Physics, Bryn Mawr College , 101 North Merion Avenue, Bryn Mawr, Pennsylvania 19010-2899, United States
| | | | - Arnold L Rheingold
- Department of Chemistry and Biochemistry, University of California, San Diago , 5128 Urey Hall, 9500 Gilman Drive, La Jolla, California 92093-0358, United States
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Beckmann PA, Rheingold AL. 1H and 19F spin-lattice relaxation and CH3 or CF3 reorientation in molecular solids containing both H and F atoms. J Chem Phys 2016; 144:154308. [DOI: 10.1063/1.4944981] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Beckmann PA, Moore CE, Rheingold AL. Methyl and t-butyl group rotation in a molecular solid: 1H NMR spin-lattice relaxation and X-ray diffraction. Phys Chem Chem Phys 2016; 18:1720-6. [DOI: 10.1039/c5cp04994f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report solid state 1H nuclear magnetic resonance spin-lattice relaxation experiments and X-ray diffractometry in 2-t-butyldimethylsilyloxy-6-bromonaphthalene.
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Affiliation(s)
| | - Curtis E. Moore
- Department of Chemistry and Biochemistry
- University of California
- La Jolla
- USA
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