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Tao Y, Wang X, Zou W, Luo GG, Kraka E. Unusual Intramolecular Motion of ReH 92- in K 2ReH 9 Crystal: Circle Dance and Three-Arm Turnstile Mechanisms Revealed by Computational Studies. Inorg Chem 2021; 61:1041-1050. [PMID: 34965110 DOI: 10.1021/acs.inorgchem.1c03118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The nonahydridorhenate dianion ReH92- is a unique rhenium polyhydride complex due to its remarkably high coordination number; however, its detailed polytopal rearrangement process in either solution or crystal is so far unclear. In this work, our quantum chemical calculations have identified two previously unreported fluxional mechanisms for the ReH92- dianion in the K2ReH9 crystal: three-arm turnstile rotation and circle dance mechanism. These two polytopal rearrangements in the crystal offer an alternative interpretation to the pulse and wide-line NMR spectra (Farrar et al. J. Chem. Phys. 1969, 51, 3595). The previously postulated hindered rotation of the whole ReH92- dianion in K2ReH9 (White et al. J. Chem. Soc., Faraday Trans. 2 1972, 68, 1414) turns out to be a combination of the above-mentioned two elementary fluxional processes. In addition, our calculations have confirmed the Muetterties' D3h⇌C4v rearrangement as the intramolecular motion for the ReH92- dianion in solution.
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Affiliation(s)
- Yunwen Tao
- Department of Chemistry, Southern Methodist University, 3215 Daniel Avenue, Dallas, Texas 75275-0314, United States
| | - Xianlong Wang
- Department of Bioinformatics, School of Medical Technology and Engineering, Key Laboratory of Medical Bioinformatics, Key Laboratory of Ministry of Education for Gastrointestinal Cancer, Fujian Medical University, Fuzhou 350122, P. R. China.,School and Hospital of Stomatology, Fujian Medical University, Fuzhou 350002, P. R. China
| | - Wenli Zou
- Institute of Modern Physics, Northwest University, and Shaanxi Key Laboratory for Theoretical Physics Frontiers, Xi'an, Shaanxi 710127, P. R. China
| | - Geng-Geng Luo
- Key Laboratory of Environmental Friendly Function Materials, Ministry of Education, and College of Materials Science and Engineering, Huaqiao University, Xiamen, Fujian 361021, P. R. China
| | - Elfi Kraka
- Department of Chemistry, Southern Methodist University, 3215 Daniel Avenue, Dallas, Texas 75275-0314, United States
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Chadwick FM, McKay AI, Martinez-Martinez AJ, Rees NH, Krämer T, Macgregor SA, Weller AS. Solid-state molecular organometallic chemistry. Single-crystal to single-crystal reactivity and catalysis with light hydrocarbon substrates. Chem Sci 2017; 8:6014-6029. [PMID: 28989631 PMCID: PMC5625289 DOI: 10.1039/c7sc01491k] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 07/05/2017] [Indexed: 01/24/2023] Open
Abstract
Solid-state molecular organometallic catalysis (SMOM-cat): synthetic routes, unique structural motifs, mobility in the solid-state and very active gas/solid isomerization catalysts.
Single-crystal to single-crystal solid/gas reactivity and catalysis starting from the precursor sigma-alkane complex [Rh(Cy2PCH2CH2PCy2)(η2η2-NBA)][BArF4] (NBA = norbornane; ArF = 3,5-(CF3)2C6H3) is reported. By adding ethene, propene and 1-butene to this precursor in solid/gas reactions the resulting alkene complexes [Rh(Cy2PCH2CH2PCy2)(alkene)x][BArF4] are formed. The ethene (x = 2) complex, [Rh(Cy2PCH2CH2PCy2)(ethene)2][BArF4]-Oct, has been characterized in the solid-state (single-crystal X-ray diffraction) and by solution and solid-state NMR spectroscopy. Rapid, low temperature recrystallization using solution methods results in a different crystalline modification, [Rh(Cy2PCH2CH2PCy2)(ethene)2][BArF4]-Hex, that has a hexagonal microporous structure (P6322). The propene complex (x = 1) [Rh(Cy2PCH2CH2PCy2)(propene)][BArF4] is characterized as having a π-bound alkene with a supporting γ-agostic Rh···H3C interaction at low temperature by single-crystal X-ray diffraction, variable temperature solution and solid-state NMR spectroscopy, as well as periodic density functional theory (DFT) calculations. A fluxional process occurs in both the solid-state and solution that is proposed to proceed via a tautomeric allyl-hydride. Gas/solid catalytic isomerization of d3-propene, H2C
Created by potrace 1.16, written by Peter Selinger 2001-2019
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CHCD3, using [Rh(Cy2PCH2CH2PCy2)(η2η2-NBA)][BArF4] scrambles the D-label into all possible positions of the propene, as shown by isotopic perturbation of equilibrium measurements for the agostic interaction. Periodic DFT calculations show a low barrier to H/D exchange (10.9 kcal mol–1, PBE-D3 level), and GIPAW chemical shift calculations guide the assignment of the experimental data. When synthesized using solution routes a bis-propene complex, [Rh(Cy2PCH2CH2PCy2)(propene)2][BArF4], is formed. [Rh(Cy2PCH2CH2PCy2)(butene)][BArF4] (x = 1) is characterized as having 2-butene bound as the cis-isomer and a single Rh···H3C agostic interaction. In the solid-state two low-energy fluxional processes are proposed. The first is a simple libration of the 2-butene that exchanges the agostic interaction, and the second is a butene isomerization process that proceeds via an allyl-hydride intermediate with a low computed barrier of 14.5 kcal mol–1. [Rh(Cy2PCH2CH2PCy2)(η2η2-NBA)][BArF4] and the polymorphs of [Rh(Cy2PCH2CH2PCy2)(ethene)2][BArF4] are shown to be effective in solid-state molecular organometallic catalysis (SMOM-Cat) for the isomerization of 1-butene to a mixture of cis- and trans-2-butene at 298 K and 1 atm, and studies suggest that catalysis is likely dominated by surface-active species. [Rh(Cy2PCH2CH2PCy2)(η2η2-NBA)][BArF4] is also shown to catalyze the transfer dehydrogenation of butane to 2-butene at 298 K using ethene as the sacrificial acceptor.
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Affiliation(s)
- F Mark Chadwick
- Department of Chemistry , Chemistry Research Laboratories , University of Oxford , OX1 3TA , UK .
| | - Alasdair I McKay
- Department of Chemistry , Chemistry Research Laboratories , University of Oxford , OX1 3TA , UK .
| | | | - Nicholas H Rees
- Department of Chemistry , Chemistry Research Laboratories , University of Oxford , OX1 3TA , UK .
| | - Tobias Krämer
- Institute of Chemical Sciences , Heriot Watt University , Edinburgh , EH14 4AS , UK .
| | - Stuart A Macgregor
- Institute of Chemical Sciences , Heriot Watt University , Edinburgh , EH14 4AS , UK .
| | - Andrew S Weller
- Department of Chemistry , Chemistry Research Laboratories , University of Oxford , OX1 3TA , UK .
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Golob S, Perry M, Lusi M, Chierotti MR, Grabnar I, Lassiani L, Voinovich D, Zaworotko MJ. Improving Biopharmaceutical Properties of Vinpocetine Through Cocrystallization. J Pharm Sci 2016; 105:3626-3633. [DOI: 10.1016/j.xphs.2016.09.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 08/31/2016] [Accepted: 09/16/2016] [Indexed: 01/08/2023]
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Chadwick FM, Krämer T, Gutmann T, Rees NH, Thompson AL, Edwards AJ, Buntkowsky G, Macgregor SA, Weller AS. Selective C-H Activation at a Molecular Rhodium Sigma-Alkane Complex by Solid/Gas Single-Crystal to Single-Crystal H/D Exchange. J Am Chem Soc 2016; 138:13369-13378. [PMID: 27631345 DOI: 10.1021/jacs.6b07968] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The controlled catalytic functionalization of alkanes via the activation of C-H bonds is a significant challenge. Although C-H activation by transition metal catalysts is often suggested to operate via intermediate σ-alkane complexes, such transient species are difficult to observe due to their instability in solution. This instability may be controlled by use of solid/gas synthetic techniques that enable the isolation of single-crystals of well-defined σ-alkane complexes. Here we show that, using this unique platform, selective alkane C-H activation occurs, as probed by H/D exchange using D2, and that five different isotopomers/isotopologues of the σ-alkane complex result, as characterized by single-crystal neutron diffraction studies for three examples. Low-energy fluxional processes associated with the σ-alkane ligand are identified using variable-temperature X-ray diffraction, solid-state NMR spectroscopy, and periodic DFT calculations. These observations connect σ-alkane complexes with their C-H activated products, and demonstrate that alkane-ligand mobility, and selective C-H activation, are possible when these processes occur in the constrained environment of the solid-state.
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Affiliation(s)
- F Mark Chadwick
- Department of Chemistry, Mansfield Road, University of Oxford , Oxford OX1 3TA, U.K
| | - Tobias Krämer
- Institute of Chemical Sciences, Heriot-Watt University , Edinburgh EH14 4AS, U.K
| | - Torsten Gutmann
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt , Alarich-Weiss-Strasse 8, D-64287 Darmstadt, Germany
| | - Nicholas H Rees
- Department of Chemistry, Mansfield Road, University of Oxford , Oxford OX1 3TA, U.K
| | - Amber L Thompson
- Department of Chemistry, Mansfield Road, University of Oxford , Oxford OX1 3TA, U.K
| | - Alison J Edwards
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organization , Locked Bag 2001 Kirrawee D.C., New South Wales 2232, Australia
| | - Gerd Buntkowsky
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt , Alarich-Weiss-Strasse 8, D-64287 Darmstadt, Germany
| | - Stuart A Macgregor
- Institute of Chemical Sciences, Heriot-Watt University , Edinburgh EH14 4AS, U.K
| | - Andrew S Weller
- Department of Chemistry, Mansfield Road, University of Oxford , Oxford OX1 3TA, U.K
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Pettinari R, Marchetti F, Pettinari C, Condello F, Skelton BW, White AH, Chierotti MR, Gobetto R. Self-assembly of arene ruthenium acylpyrazolone fragments to tetranuclear metallacycles. Molecular structures and solid-state 15N CPMAS NMR correlations. Dalton Trans 2016; 45:3974-82. [DOI: 10.1039/c6dt00168h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mono- and tetranuclear Ru(ii) half-sandwich complexes containing acylpyrazolone ligands. 13C and 15N solid state NMR spectroscopy.
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Affiliation(s)
| | - Fabio Marchetti
- School of Science and Technology
- University of Camerino
- 62032 Camerino
- Italy
| | | | | | - Brian W. Skelton
- School of Chemistry and Biochemistry M310
- The University of Western Australia
- Crawley
- Australia
| | - Allan H. White
- Centre for Microscopy
- Characterization and Analysis M010
- The University of Western Australia
- Crawley
- Australia
| | | | - Roberto Gobetto
- Dipartimento di Chimica and NIS Centre
- University of Torino
- 10125 Torino
- Italy
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Cluff KJ, Bhuvanesh N, Blümel J. Monometallic Ni(0) and Heterobimetallic Ni(0) /Au(I) Complexes of Tripodal Phosphine Ligands: Characterization in Solution and in the Solid State and Catalysis. Chemistry 2015; 21:10138-48. [PMID: 26059108 DOI: 10.1002/chem.201500187] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Revised: 04/23/2015] [Indexed: 11/07/2022]
Abstract
The tridentate chelate nickel complexes [(CO)Ni{(PPh2 CH2 )3 CMe}] (2), [(CO)Ni{(PPh2 CH2 CH2 )3 SiMe}] (6), and [Ph3 PNi{(PPh2 CH2 CH2 )3 SiMe}] (7), as well as the bidentate complex [(CO)2 Ni{(PPh2 CH2 )2 CMeCH2 PPh2 }] (3) and the heterobimetallic complex [(CO)2 Ni{(PPh2 CH2 )2 CMeCH2 Ph2 PAuCl}] (4), have been synthesized and fully characterized in solution. All (1) H and (13) C NMR signal assignments are based on 2D-NMR methods. Single crystal X-ray structures have been obtained for all complexes. Their (31) P CP/MAS (cross polarization with magic angle spinning) NMR spectra have been recorded and the isotropic lines identified. The signals were assigned with the help of their chemical shift anisotropy (CSA) data. All complexes have been tested regarding their catalytic activity for the cyclotrimerization of phenylacetylene. Whereas complexes 2-4 display low catalytic activity, complex 7 leads to quantitative conversion of the substrate within four hours and is highly selective throughout the catalytic reaction.
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Affiliation(s)
- Kyle J Cluff
- Department of Chemistry, Texas A & M University, College Station, TX, 77842-3012 (USA)
| | - Nattamai Bhuvanesh
- Department of Chemistry, Texas A & M University, College Station, TX, 77842-3012 (USA)
| | - Janet Blümel
- Department of Chemistry, Texas A & M University, College Station, TX, 77842-3012 (USA).
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Marchetti F, Palmucci J, Pettinari C, Pettinari R, Condello F, Ferraro S, Marangoni M, Crispini A, Scuri S, Grappasonni I, Cocchioni M, Nabissi M, Chierotti MR, Gobetto R. Novel composite plastics containing silver(I) acylpyrazolonato additives display potent antimicrobial activity by contact. Chemistry 2014; 21:836-50. [PMID: 25358838 DOI: 10.1002/chem.201404812] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Indexed: 12/20/2022]
Abstract
New silver(I) acylpyrazolonato derivatives displaying a mononuclear, polynuclear, or ionic nature, as a function of the ancillary azole ligands used in the synthesis, have been fully characterized by thermal analysis, solution NMR spectroscopy, solid-state IR and NMR spectroscopies, and X-ray diffraction techniques. These derivatives have been embedded in polyethylene (PE) matrix, and the antimicrobial activity of the composite materials has been tested against three bacterial strains (E. coli, P. aeruginosa, and S. aureus): Most of the composites show antimicrobial action comparable to PE embedded with AgNO3 . Tests by contact and release tests for specific migration of silver from PE composites clearly indicate that, at least in the case of the PE, for composites containing polynuclear silver(I) additives, the antimicrobial action is exerted by contact, without release of silver ions. Moreover, PE composites can be re-used several times, displaying the same antimicrobial activity. Membrane permeabilization studies and induced reactive oxygen species (ROS) generation tests confirm the disorganization of bacterial cell membranes. The cytotoxic effect, evaluated in CD34(+) cells by MTT (3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazoliumbromide) and CFU (colony forming units) assays, indicates that the PE composites do not induce cytotoxicity in human cells. Studies of ecotoxicity, based on the test of Daphnia magna, confirm tolerability of the PE composites by higher organisms and exclude the release of Ag(+) ions in sufficient amounts to affect water environment.
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Affiliation(s)
- Fabio Marchetti
- School of Science and Technology, Chemistry Section, University of Camerino, Via S. Agostino 1, Camerino (MC) (Italy).
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Garino C, Borfecchia E, Gobetto R, van Bokhoven JA, Lamberti C. Determination of the electronic and structural configuration of coordination compounds by synchrotron-radiation techniques. Coord Chem Rev 2014. [DOI: 10.1016/j.ccr.2014.03.027] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Smart KA, Grellier M, Coppel Y, Vendier L, Mason SA, Capelli SC, Albinati A, Montiel-Palma V, Muñoz-Hernández MA, Sabo-Etienne S. Nature of Si-H interactions in a series of ruthenium silazane complexes using multinuclear solid-state NMR and neutron diffraction. Inorg Chem 2014; 53:1156-65. [PMID: 24392827 DOI: 10.1021/ic4027199] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Three new N-heterocyclic-silazane compounds, 1a-c, were prepared and employed as bidentate ligands to ruthenium, resulting in a series of [Ru(H){(κ-Si,N-(SiMe2-N-heterocycle)}3] complexes (3a-c) featuring the same RuSi3H motif. Detailed structural characterization of the RuSi3H complexes with X-ray diffraction, and in the case of triazabicyclo complex [Ru(H){κ-Si,N-(SiMe2)(C7H12N3)}3] (3a), neutron diffraction, enabled a reliable description of the molecular geometry. The hydride ligand of (3a) is located closer to two of the silicon atoms than it is to the third. Such a geometry differs from that of the previously reported complex [Ru(H){(κ-Si,N-(SiMe2)N(SiMe2H)(C5H4N)}3] (3d), also characterized by neutron diffraction, where the hydride was found to be equidistant from all three silicon atoms. A DFT study revealed that the symmetric and less regular isomers are essentially degenerate. Information on the dynamics and on the Ru···H···Si interactions was gained from multinuclear solid-state ((1)H wPMLG, (29)Si CP MAS, and 2D (1)H-(29)Si dipolar HETCOR experiments) and solution NMR studies. The corresponding intermediate complexes, [Ru{κ-Si,N-(SiMe2-N-heterocycle)}(η(4)-C8H12)(η(3)-C8H11)] (2a-c), involving a single silazane ligand were isolated and characterized by multinuclear NMR and X-ray diffraction. Protonation of the RuSi3H complexes was also studied. Reaction of 3a with NH4PF6 gave rise to [Ru(H)(η(2)-H -SiMe2)κ-N-(C7H12N3){κ-Si,N-(SiMe2)(C7H12N3)}2](+)[PF6](-)(4aPF6) which was isolated and characterized by NMR spectroscopy, X-ray crystallography, and DFT studies. The nature of the Si-H interactions in this silazane series was analyzed in detail.
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Affiliation(s)
- Katharine A Smart
- LCC (Laboratoire de Chimie de Coordination), CNRS , 205 Route de Narbonne, F-31077 Toulouse, France
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Mechanochemically induced disordered structures of vincamine: The different mediation of two cross-linked polymers. Int J Pharm 2012; 436:41-57. [DOI: 10.1016/j.ijpharm.2012.06.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Revised: 06/01/2012] [Accepted: 06/03/2012] [Indexed: 11/22/2022]
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12
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Rossin A, Chierotti MR, Giambastiani G, Gobetto R, Peruzzini M. Amine-templated polymeric Mg formates: crystalline scaffolds exhibiting extensive hydrogen bonding. CrystEngComm 2012. [DOI: 10.1039/c2ce25048a] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Diana E, Chierotti MR, Marchese EMC, Croce G, Milanesio M, Stanghellini PL. Blue and red shift hydrogen bonds in crystalline cobaltocinium complexes. NEW J CHEM 2012. [DOI: 10.1039/c2nj20760e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Többens DM, Glinneman J, Chierotti MR, van de Streek J, Sheptyakov D. On the high-temperature phase of barbituric acid. CrystEngComm 2012. [DOI: 10.1039/c2ce06636j] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Gloaguen Y, Alcaraz G, Petit AS, Clot E, Coppel Y, Vendier L, Sabo-Etienne S. Ruthenium Agostic (Phosphinoaryl)borane Complexes: Multinuclear Solid-State and Solution NMR, X-ray, and DFT Studies. J Am Chem Soc 2011; 133:17232-8. [DOI: 10.1021/ja203828r] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yann Gloaguen
- CNRS, LCC (Laboratoire de Chimie de Coordination), 205 Route de Narbonne, F-31077 Toulouse, France
- Université de Toulouse, UPS, INPT, F-31077 Toulouse, France
| | - Gilles Alcaraz
- CNRS, LCC (Laboratoire de Chimie de Coordination), 205 Route de Narbonne, F-31077 Toulouse, France
- Université de Toulouse, UPS, INPT, F-31077 Toulouse, France
| | - Alban S. Petit
- Institut Charles Gerhardt, CNRS 5253, Université Montpellier 2, cc 1501, Place Eugène Bataillon, 34095 Montpellier, France
| | - Eric Clot
- Institut Charles Gerhardt, CNRS 5253, Université Montpellier 2, cc 1501, Place Eugène Bataillon, 34095 Montpellier, France
| | - Yannick Coppel
- CNRS, LCC (Laboratoire de Chimie de Coordination), 205 Route de Narbonne, F-31077 Toulouse, France
- Université de Toulouse, UPS, INPT, F-31077 Toulouse, France
| | - Laure Vendier
- CNRS, LCC (Laboratoire de Chimie de Coordination), 205 Route de Narbonne, F-31077 Toulouse, France
- Université de Toulouse, UPS, INPT, F-31077 Toulouse, France
| | - Sylviane Sabo-Etienne
- CNRS, LCC (Laboratoire de Chimie de Coordination), 205 Route de Narbonne, F-31077 Toulouse, France
- Université de Toulouse, UPS, INPT, F-31077 Toulouse, France
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Carignani E, Borsacchi S, Geppi M. Dynamics by solid-state NMR: detailed study of ibuprofen Na salt and comparison with ibuprofen. J Phys Chem A 2011; 115:8783-90. [PMID: 21744822 DOI: 10.1021/jp202650n] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The various internal rotations and interconformational jumps of the Na-salt form of ibuprofen in the solid state were characterized in detail by means of the simultaneous analysis of a variety of low- and high-resolution NMR experiments aimed at measuring several (13)C and (1)H spectral and relaxation properties at different temperatures and frequencies. The results were first qualitatively analyzed to identify the motions of the different molecular fragments and to assign them to specific frequency regimes (slow, <10(3) Hz; intermediate, 10(3)-10(6) Hz; and fast, >10(6) Hz). Subsequently, a simultaneous fit of the experimental data sets most sensitive to each frequency range was performed by using suitable motional models, thus obtaining, for each motion, correlation times and activation energies. The motions so characterized were: the rotations of the three methyl groups and of the isobutyl group, occurring in the fast regime, and the π-flip of the phenyl ring, belonging to the intermediate motional regime. The results obtained for the Na-salt form were compared with those of the acidic form of ibuprofen, previously obtained from a similar solid-state NMR approach: despite the very similar chemical structure of the two compounds, their dynamic properties in the solid state are noticeably different.
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Affiliation(s)
- Elisa Carignani
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, v. Risorgimento 35, 56126 Pisa, Italy
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Carignani E, Borsacchi S, Geppi M. Detailed characterization of the dynamics of ibuprofen in the solid state by a multi-technique NMR approach. Chemphyschem 2011; 12:974-81. [PMID: 21381176 DOI: 10.1002/cphc.201000946] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2011] [Indexed: 02/05/2023]
Abstract
The internal rotations and interconformational jumps of ibuprofen in the solid state are fully characterized by the simultaneous analysis of a variety of low- and high-resolution NMR experiments for the measurement of several (13)C and (1)H spectral and relaxation properties, performed at different temperatures and, in some cases, frequencies. The results are first qualitatively analyzed to identify the motions of the different molecular fragments and to assign them to specific frequency ranges (slow, <10(3) Hz; intermediate, 10(3)-10(6) Hz; and fast, >10(6) Hz). In a second step, a simultaneous fit of the experimental data sets most sensitive to each frequency range is performed by means of suitable motional models to obtain, for each motion, values of correlation times and activation energies. The rotations of the three methyl groups around their ternary symmetry axes, which occur in the fast regime, are characterized by slightly different activation energies. Thanks to the simultaneous analysis of (1)H and (13)C data, the π-flip of the dimeric structure made by the acidic groups is also identified and seen to occur in the fast regime. On the contrary, the π-flip of the phenyl ring is found to occur in the slow motional regime, while the rotations of the isobutyl and propionic groups are frozen. The approach used appears to be of general applicability for studying the dynamics of small organic molecules.
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Affiliation(s)
- Elisa Carignani
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Risorgimento 35, 56126 Pisa, Italy
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