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Klabunde S, Doerenkamp C, de Oliveira M, Zeng Z, Eckert H. Inorganic-organic hybrid materials based on the intercalation of radical cations: 2-(4-N-methylpyridinium)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxyl-3-N-oxide in fluoromica clay. Z PHYS CHEM 2021. [DOI: 10.1515/zpch-2021-3133] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
A systematic structural study on the intercalation of the radical cation 2-(4-N-methylpyridinium)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxyl-3-N-oxide (p-MPYNN) into a synthetic fluoromica clay named Somasif® ME 100, Na2x
Mg3.0−x
Si4O10(F
y
OH1−y
)2 (x = 0.33, y = 0.98), has been carried out. The guest–host interactions in these intercalation compounds have been characterized by X-ray powder diffraction and solid-state NMR of the constituent nuclei (23Na, 19F, 27Al and 29Si) of the Somasif lattice. The intercalation process can be quantitatively monitored using 23Na MAS-NMR. As a function of radical ion loading, different kinds of stacking arrangements can be realized, which modify the intermolecular interactions between the electron spins of the guest species, as probed by electron spin resonance (EPR) and 1H solid state nuclear magnetic resonance (NMR). The results are discussed in relation to previous literature data on similar systems.
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Affiliation(s)
- Sina Klabunde
- Institut für Physikalische Chemie, Westfälische Wilhelms-Universität Münster , Corrensstr. 28/30 , 48149 Münster , Germany
| | - Carsten Doerenkamp
- Institut für Physikalische Chemie, Westfälische Wilhelms-Universität Münster , Corrensstr. 28/30 , 48149 Münster , Germany
| | - Marcos de Oliveira
- Instituto de Física, Universidade de São Paulo , Av. Trabalhador Sãocarlense 400 , São Carlos , S.P. 13566 590 , Brazil
| | - Zhaoyang Zeng
- Institut für Physikalische Chemie, Westfälische Wilhelms-Universität Münster , Corrensstr. 28/30 , 48149 Münster , Germany
| | - Hellmut Eckert
- Institut für Physikalische Chemie, Westfälische Wilhelms-Universität Münster , Corrensstr. 28/30 , 48149 Münster , Germany
- Instituto de Física, Universidade de São Paulo , Av. Trabalhador Sãocarlense 400 , São Carlos , S.P. 13566 590 , Brazil
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Fuentealba P, Olea C, Aguilar-Bolados H, Audebrand N, de Santana RC, Doerenkamp C, Eckert H, Magon CJ, Spodine E. Physical properties of new ordered bimetallic phases M 0.25Cd 0.75PS 3 (M = Zn II, Ni II, Co II, Mn II). Phys Chem Chem Phys 2020; 22:8315-8324. [PMID: 32159561 DOI: 10.1039/d0cp00631a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Four bimetallic phases of the thiophosphate family have been synthesized by the cationic exchange reaction using a freshly prepared K0.5Cd0.75PS3 precursor phase and methanolic solutions of nitrates of the divalent cations ZnII, NiII, CoII, and MnII. All the materials were characterized by FTIR, PXRD, SEM-EDXS and (in the case of the diamagnetic compounds) by solid state NMR. For the K0.5Cd0.75PS3 precursor, the X-ray powder diffraction data suggest a modification of the structure, while solid state NMR results confirm that this phase possesses an ordered arrangement of Cd vacancies. The cationic exchange reaction achieves a complete removal of potassium ions (no potassium detected by SEM-EDXS) and re-occupation of the vacancies by divalent cations. Therefore, the obtained compounds have an average composition of M0.25Cd0.75PS3 (M = ZnII, NiII, CoII, MnII) and possess an ordered distribution of the substituent cations. Even with the paramagnetic substitution level of 25%, antiferromagnetic behaviour is present in the phases with MnII, CoII and NiII, as evidenced by dc susceptibility and in the case of the MnII substituted phase by EPR. The cooperative magnetic interactions confirm the conclusion that the paramagnetic ions adopt an ordered arrangement. The analysis by broad band impedance spectroscopy allows to attribute the conductivity in these materials to charge movements in the layers due to the difference in electronegativity of the metal ions. Zn0.25Cd0.75PS3 is the phase that shows the highest conductivity values. Finally, the band gap energies of the bimetallic phases tend to be lower than those of the single-metal phases, probably due to an overlap of the band structures.
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Affiliation(s)
- P Fuentealba
- Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile. and Centro para el Desarrollo de Nanociencias y Nanotecnología, CEDENNA, Santiago, Chile
| | - C Olea
- Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile.
| | - H Aguilar-Bolados
- Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile.
| | - N Audebrand
- Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) - UMR 6226, F-35000 Rennes, France
| | - R C de Santana
- Instituto de Física, Universidade Federal de Goiás, Goiânia, Brazil
| | - C Doerenkamp
- Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, Brazil
| | - H Eckert
- Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, Brazil
| | - C J Magon
- Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, Brazil
| | - E Spodine
- Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile. and Centro para el Desarrollo de Nanociencias y Nanotecnología, CEDENNA, Santiago, Chile
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Magdesieva TV, Levitskiy OA. Molecular design of stable diarylnitroxides. RUSSIAN CHEMICAL REVIEWS 2018. [DOI: 10.1070/rcr4769] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The review is devoted to diarylnitroxides, which constitute an important type of organic radicals. These compounds are much less investigated than their alkyl counterparts. Meanwhile, they are of great interest, since they provide extensive opportunities for targeted structural modification and control of electronic properties of a molecule for a particular practical application. The existing trends of molecular design of stable diarylnitroxides and general approaches to their synthesis are discussed. Structural details and spin density distribution in diarylnitroxides are considered. Factors determining the stability of both the diarylnitroxide radicals and their oxidized and reduced forms and the redox properties of this class of organic radicals are addressed.
The bibliography includes 128 references.
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Eusterwiemann S, Doerenkamp C, Dresselhaus T, Janka O, de Oliveira M, Daniliuc CG, Eckert H, Neugebauer J, Pöttgen R, Studer A. Strong intermolecular antiferromagnetic verdazyl-verdazyl coupling in the solid state. Phys Chem Chem Phys 2017; 19:15681-15685. [PMID: 28604873 DOI: 10.1039/c7cp02950k] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Strong magnetic couplings are generally observed intramolecularly in organic diradicals or in systems in which they are promoted by crystal engineering strategies involving, for example, transition metal ligation. We herein present a strong intermolecularly coupling verdazyl radical in the solid state without the use of such design strategies. The crystal structure of an acetylene-substituted verdazyl radical shows a unique antiparallel face-to-face orientation of the neighboring verdazyl molecules along with verdazyl-acetylene interactions giving rise to an alternating antiferromagnetic Heisenberg chain. Single crystal structural data at 80, 100, 173, and 223 K show that one of the π-stacking distances depends on temperature, while heat capacity data indicate the absence of a phase transition. Based on this structural input, broken symmetry DFT calculations predict a change from an alternating linear Heisenberg chain with two comparable coupling constants J1 and J2 at higher temperatures towards dominant pair interactions at lower temperatures. The predicted antiferromagnetic coupling is confirmed experimentally by magnetic susceptibility, solid-state EPR and NMR spectroscopic results.
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Affiliation(s)
- S Eusterwiemann
- Institute of Organic Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, 48149 Münster, Germany.
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Eckert H. Advanced Magnetic Resonance Techniques for the Structural Characterization of Aminoxyl Radicals and Their Inorganic-Organic Nanocomposite Systems. Chemistry 2017; 23:5893-5914. [PMID: 27862449 DOI: 10.1002/chem.201604685] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Indexed: 11/10/2022]
Abstract
Electron and nuclear spins are extremely sensitive probes of their local structural and dynamic surroundings. Their Zeeman energy levels are modified by different types of local magnetic and electric fields created by their structural environment, which influence their magnetic resonance condition. For this reason, electron spin resonance (ESR) and nuclear magnetic resonance (NMR) spectroscopies have become extremely powerful tools of structural analysis, which are being widely used for the structural characterization of complex solids. Following a brief introduction into the basic theoretical foundations the most commonly used techniques and their application towards the structural characterization of paramagnetic solids based on aminoxyl radicals and their inorganic-organic nanocomposites will be described. Both ESR and NMR observables are useful for monitoring intermolecular interactions between unpaired electron spins, which are particularly important for the design of organically based ferromagnetic systems. ESR and NMR methods based on this effect can be used for monitoring the synthesis of polynitroxides and for evaluating the catalytic function of aminoxyl intercalation compounds. Finally, the sensitivity of ESR signals to motional dynamics can be exploited for characterizing molecule-surface interactions in nanocomposite systems. In the context of the latter work recently developed signal enhancement strategies are described, using polarization transfer from electron spins to nuclear spins for NMR spectroscopic detection.
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Affiliation(s)
- Hellmut Eckert
- Institut für Physikalische Chemie, WWU Münster, Corrensstraße 30, 48149, Münster, Germany.,Instituto de Física São Carlos, Universidade de São Paulo, CP 369, 13560-970, São Carlos, S.P., Brasil
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de Vries W, Doerenkamp C, Zeng Z, de Oliveira M, Niehaus O, Pöttgen R, Studer A, Eckert H. Synthesis and characterization of amorphous mesoporous silica using TEMPO-functionalized amphiphilic templates. J SOLID STATE CHEM 2016. [DOI: 10.1016/j.jssc.2016.01.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Zeng Z, Matuschek D, Studer A, Schwickert C, Pöttgen R, Eckert H. Synthesis and characterization of inorganic–organic hybrid materials based on the intercalation of stable organic radicals into a fluoromica clay. Dalton Trans 2013; 42:8585-96. [DOI: 10.1039/c3dt50627d] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Mas-Torrent M, Crivillers N, Rovira C, Veciana J. Attaching persistent organic free radicals to surfaces: how and why. Chem Rev 2011; 112:2506-27. [PMID: 22188381 DOI: 10.1021/cr200233g] [Citation(s) in RCA: 144] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Marta Mas-Torrent
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193 Bellaterra, Spain.
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Hemme WL, Fujita W, Awaga K, Eckert H. Solid state NMR strategies for the structural characterization of new hybrid materials based on the intercalation of nitroxide radicals into CdPS3. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2011; 39:106-115. [PMID: 21543192 DOI: 10.1016/j.ssnmr.2011.03.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Indexed: 05/30/2023]
Abstract
The radical cations 2-(3-N-butylpyridinium)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxyl-3-N-oxide (m-BuPYNN) and 4-(ethylammonium)-2,2,6,6-tetramethylpiperidin-1-oxide (EATEP) are successfully intercalated into the layered host structure of CdPS(3) via ion exchange. The reaction proceeds either directly from ethanolic solutions of the radical iodide salt or via a two-stage process involving first the formation of an intermediate tetramethylammonium intercalate. The resulting materials, which are described by the compositional formula Cd(1-x)PS(3){Rad}(2x), are characterized by chemical analysis, X-ray powder diffraction, bulk susceptibility measurements and EPR spectroscopy. Modern single and double resonance solid state NMR techniques are introduced successfully to study the structural modifications of the host lattice and the details of the intermolecular guest/host interactions. (1)H MAS-NMR spectra reveal substantial differences in the unpaired electron spin density distributions within the radical ions intercalated into the host lattice compared to those obtained for the pure radical ion salts, leading to different bulk magnetic properties. The results of (1)H/(31)P double resonance experiments indicate that the orientation of the guest molecules is dominated by Columbic interactions between the radical cations and the negatively charged cadmium vacancies in the host lattice.
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Affiliation(s)
- Wilhelm L Hemme
- Institut für Physikalische Chemie, Westfälische Wilhelms-Universität, Corrensstrasse 30, 48149 Münster, Germany
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