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Luo SM, Stellmach KA, Ikuzwe SM, Cao DD. Redox-Active Heteroacene Chromophores Derived from a Nonlinear Aromatic Diimide. J Org Chem 2019; 84:10362-10370. [DOI: 10.1021/acs.joc.9b01502] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Stella M. Luo
- Chemistry Department, Macalester College, 1600 Grand Avenue, Saint Paul, Minnesota 55105, United States
| | - Kellie A. Stellmach
- Chemistry Department, Macalester College, 1600 Grand Avenue, Saint Paul, Minnesota 55105, United States
| | - Stella M. Ikuzwe
- Chemistry Department, Macalester College, 1600 Grand Avenue, Saint Paul, Minnesota 55105, United States
| | - Dennis D. Cao
- Chemistry Department, Macalester College, 1600 Grand Avenue, Saint Paul, Minnesota 55105, United States
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Determination of the Full 207Pb Chemical Shift Tensor of Anglesite, PbSO4, and Correlation of the Isotropic Shift to Lead–Oxygen Distance in Natural Minerals. CRYSTALS 2019. [DOI: 10.3390/cryst9010043] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The full 207 Pb chemical shift (CS) tensor of lead in the mineral anglesite, PbSO 4 , was determined from orientation-dependent nuclear magnetic resonance (NMR) spectra of a large natural single crystal, using a global fit over two rotation patterns. The resulting tensor is characterised by the reduced anisotropy Δ δ = ( - 327 ± 4 ) ppm, asymmetry η C S = 0 . 529 ± 0 . 002 , and δ i s o = ( - 3615 ± 3 ) ppm, with the isotropic chemical shift δ i s o also verified by magic-angle spinning NMR on a polycrystalline sample. The initially unknown orientation of the mounted single crystal was included in the global data fit as well, thus obtaining it from NMR data only. By use of internal crystal symmetries, the amount of data acquisition and processing for determination of the CS tensor and crystal orientation was reduced. Furthermore, a linear correlation between the 207 Pb isotropic chemical shift and the shortest Pb–O distance in the co-ordination sphere of Pb 2 + solely surrounded by oxygen has been established for a large database of lead-bearing natural minerals.
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Roiland C, Trippé-Allard G, Jemli K, Alonso B, Ameline JC, Gautier R, Bataille T, Le Pollès L, Deleporte E, Even J, Katan C. Multinuclear NMR as a tool for studying local order and dynamics in CH 3NH 3PbX 3 (X = Cl, Br, I) hybrid perovskites. Phys Chem Chem Phys 2018; 18:27133-27142. [PMID: 27722277 DOI: 10.1039/c6cp02947g] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
We report on 207Pb, 79Br, 14N, 1H, 13C and 2H NMR experiments for studying the local order and dynamics in hybrid perovskite lattices. 207Pb NMR experiments conducted at room temperature on a series of MAPbX3 compounds (MA = CH3NH3+; X = Cl, Br and I) showed that the isotropic 207Pb NMR shift is strongly dependent on the nature of the halogen ions. Therefore 207Pb NMR appears to be a very promising tool for the characterisation of local order in mixed halogen hybrid perovskites. 207Pb NMR on MAPbBr2I served as a proof of concept. Proton, 13C and 14N NMR experiments confirmed the results previously reported in the literature. Low temperature deuterium NMR measurements, down to 25 K, were carried out to investigate the structural phase transitions of MAPbBr3. Spectral lineshapes allow following the successive phase transitions of MAPbBr3. Finally, quadrupolar NMR lineshapes recorded in the orthorhombic phase were compared with simulated spectra, using DFT calculated electric field gradients (EFG). Computed data do not take into account any temperature effect. Thus, the discrepancy between the calculated and experimental EFG evidences the fact that MA cations are still subject to significant dynamics, even at 25 K.
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Affiliation(s)
- Claire Roiland
- Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS - Ecole Nationale Supérieure de Chimie de Rennes - Université de Rennes 1, 35042 Rennes, France.
| | - Gaelle Trippé-Allard
- Laboratoire Aimé Cotton, UMR 9188 CNRS - Ecole Normale Supérieure de Cachan - Université Paris-Sud, 91405 Orsay, France
| | - Khaoula Jemli
- Laboratoire Aimé Cotton, UMR 9188 CNRS - Ecole Normale Supérieure de Cachan - Université Paris-Sud, 91405 Orsay, France
| | - Bruno Alonso
- Institut Charles Gerhardt UMR 5253, CNRS-ENSCM-UM1-UM2, 8 rue de l'Ecole Normale, 34296 Montpellier Cedex 5, France
| | - Jean-Claude Ameline
- Institut de Physique de Rennes, UMR 6251 CNRS - Université de Rennes 1, 35042 Rennes, France
| | - Régis Gautier
- Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS - Ecole Nationale Supérieure de Chimie de Rennes - Université de Rennes 1, 35042 Rennes, France.
| | - Thierry Bataille
- Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS - Ecole Nationale Supérieure de Chimie de Rennes - Université de Rennes 1, 35042 Rennes, France.
| | - Laurent Le Pollès
- Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS - Ecole Nationale Supérieure de Chimie de Rennes - Université de Rennes 1, 35042 Rennes, France.
| | - Emmanuelle Deleporte
- Laboratoire Aimé Cotton, UMR 9188 CNRS - Ecole Normale Supérieure de Cachan - Université Paris-Sud, 91405 Orsay, France
| | - Jacky Even
- Fonctions Optiques pour les Technologies de l'Information, UMR 6082 CNRS - INSA de Rennes, 35708 Rennes, France.
| | - Claudine Katan
- Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS - Ecole Nationale Supérieure de Chimie de Rennes - Université de Rennes 1, 35042 Rennes, France.
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Deuteron Magnetic Resonance Studies of Anhydrous Caffeine. Z PHYS CHEM 2012. [DOI: 10.1524/zpch.2012.0333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
AbstractMethyl deuterated caffeine powder was studied using2H-NMR relaxometry and line shape analysis. In caffeine's low-temperature phase the spin-lattice relaxation times indicate a thermally activated CD3reorientation (activation energy ≈4 kJ/mol). Below theT1minimum near 35 K the quadrupolar echo spectra develop features indicative for quantum mechanical tunneling. Dielectric measurements indicate the presence of dipole moment fluctuations with times scales that follow an Arrhenius law (energy barrier ≈107 kJ/mol). It is argued that the underlying motion involves small-angle molecular excursions and therefore remains undetectedviastimulated-echo spectroscopy. The hysteresis accompanying the order/disorder transition taking place above 400 K was monitored using solid-echo line shapes as well asviaspin relaxation times. In the high-temperature phase indications for the onset of anisotropic large-angle motions were obtained.
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Goswami M, Nayak PK, Periasamy N, Madhu PK. Characterisation of different polymorphs of tris(8-hydroxyquinolinato)aluminium(III) using solid-state NMR and DFT calculations. Chem Cent J 2009; 3:15. [PMID: 19900275 PMCID: PMC2777900 DOI: 10.1186/1752-153x-3-15] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Accepted: 11/09/2009] [Indexed: 11/10/2022] Open
Abstract
Background Organic light emitting devices (OLED) are becoming important and characterisation of them, in terms of structure, charge distribution, and intermolecular interactions, is important. Tris(8-hydroxyquinolinato)-aluminium(III), known as Alq3, an organomettalic complex has become a reference material of great importance in OLED. It is important to elucidate the structural details of Alq3 in its various isomeric and solvated forms. Solid-state nuclear magnetic resonance (NMR) is a useful tool for this which can also complement the information obtained with X-ray diffraction studies. Results We report here 27Al one-dimensional (1D) and two-dimensional (2D) multiple-quantum magic-angle spinning (MQMAS) NMR studies of the meridional (α-phase) and the facial (δ-phase) isomeric forms of Alq3. Quadrupolar parameters are estimated from the 1D spectra under MAS and anisotropic slices of the 2D spectra and also calculated using DFT (density functional theory) quantum-chemical calculations. We have also studied solvated phase of Alq3 containing ethanol in its lattice. We show that both the XRD patterns and the quadrupolar parameters of the solvated phase are different from both the α-phase and the δ-phase, although the fluorescence emission shows no substantial difference between the α-phase and the solvated phase. Moreover, we have shown that after the removal of ethanol from the matrix the solvated Alq3 has similar XRD patterns and quadrupolar parameters to that of the α-phase. Conclusion The 2D MQMAS experiments have shown that all the different modifications of Alq3 have 27Al in single unique crystallographic site. The quadrupolar parameters predicted using the DFT calculation under the isodensity polarisable continuum model resemble closely the experimentally obtained values. The solvated phase of Alq3 containing ethanol has structural difference from the α-phase of Alq3 (containing meridional isomer) from the solid-state NMR studies. Solid-state NMR can hence be used as an effective complementary tool to XRD for characterisation and structural elucidation.
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Affiliation(s)
- Mithun Goswami
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Colaba, Mumbai, India.
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Singh LP, Murthy SSN, Bräuniger T, Zimmermann H. Relaxation dynamics of orientationally disordered plastic crystals: effect of dopants. J Phys Chem B 2008; 112:1594-603. [PMID: 18211059 DOI: 10.1021/jp077023l] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We have examined the relaxation that occurs in the supercooled plastic crystalline phases of pentachloronitrobenzene (PCNB), dichlorotetramethylbenzene (DCTMB), trichlorotrimethylbenzene (TCTMB) along with some of their deuterated samples, and 1-cyanoadamantane (CNADM) in the presence of intentionally added dopants. The experimental techniques used in the present study are dielectric spectroscopy and differential scanning calorimetry (DSC). Only one relaxation process similar to that of the primary (or alpha-) relaxation characteristic of glass-forming materials is found, but there is no indication of any observable secondary relaxation within the resolution of our experimental setup. The alpha-process can reasonably be described by a Havriliak-Negami (HN) shape function throughout the frequency range. However, in the case of PCNB the dielectric strength (Delta epsilon) of the above said alpha-process does not change appreciably with temperature, though interestingly, a small addition of a dopant such as pentachlorobenzene (PCB), trichlorobenzene (TCB), and chloroadamantane (CLADM) to the molten state of PCNB drastically lowers the dielectric strength by a factor of 4 to 8. Powder X-ray diffraction measurements at room temperature and DSC data do not indicate any appreciable change in the crystalline structure. It is noticed that the effect of PCB as a dopant on the magnitude of alpha-process of CNADM is moderate, whereas both PCB and TCB as dopants show a much reduced effect on the relaxation in DCTMB and TCTMB. It is suggested that the drastic changes in the dielectric strength of the alpha-process is due to the rotational hindrance caused by the presence of a small number of dopant molecules in the host crystalline lattice. In the above context, the possibility of a certain degree of antiparallel ordering of dipoles is also discussed.
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Affiliation(s)
- L P Singh
- School of Physical Sciences, Jawaharlal Nehru University, New Delhi, India
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Reichert D. Solid-state NMR spectroscopy and its application in analytical chemistry. Anal Bioanal Chem 2003; 376:308-10. [PMID: 12734631 DOI: 10.1007/s00216-003-1929-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- D Reichert
- Fachbereich Physik, Fachgruppe NMR & Biophysik, Universität Halle, Friedemann-Bach-Platz 6, Germany.
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Helluy X, Sebald A. Order-disorder phenomena in crystalline phases of compounds E(XMe3)4 where E?=?C, Si, Ge and X?=?Si, Sn. Appl Organomet Chem 2003. [DOI: 10.1002/aoc.382] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Qi F, Winterich M, Titze A, Böhmer R. Complex hopping dynamics in the deuteron conductors K3D(SO4)2 and Rb3D(SO4)2. J Chem Phys 2002. [DOI: 10.1063/1.1521161] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Affiliation(s)
- Cecil Dybowski
- Department of Chemistry and Biochemistry, University of Delaware, Newark 19716-2522, USA
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