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Houard F, Cucinotta G, Guizouarn T, Suffren Y, Calvez G, Daiguebonne C, Guillou O, Artzner F, Mannini M, Bernot K. Metallogels: a novel approach for the nanostructuration of single-chain magnets. MATERIALS HORIZONS 2023; 10:547-555. [PMID: 36426997 DOI: 10.1039/d2mh01158a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
In this study we demonstrate that single-chain magnets (SCMs) can be assembled in gel phase and transferred intact on surface. We take advantage of a family of SCMs based on TbIII ions and nitronyl-nitroxides radicals functionalized with short alkyl chains known to form crystalline supramolecular nanotubes interacting with heptane acting as crystallizing solvent. When the radicals are functionalized with long aliphatic chains a robust gel is formed with similar structural and functional properties respect to its crystalline parent. Indeed, a small-angle X-ray scattering (SAXS) study unambiguously demonstrates that the gel is made of supramolecular nanotubes: the high stability of the gel allows the determination from SAXS data of precise nanotube metrics such as diameter, helical pitch and monoclinic cell of the folded 2D crystal lattice along the tube direction. Additionally, static and dynamic magnetic investigations show the persistence of the SCM behavior in the metallogel. Last, on-surface gelation provides thick films as well as sub-monolayer deposits of supramolecular nanotubes on surface as evidenced by atomic force microscopy (AFM) observations. This paves the road toward magnetic materials and devices made of SCMs profiting of their isolation on surface as individual chains.
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Affiliation(s)
- Felix Houard
- Univ Rennes, INSA Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes), UMR 6226, Université de Rennes 1, F-35000 Rennes, France.
| | - Guiseppe Cucinotta
- Dipartimento di Chimica "Ugo Schiff" (DICUS), Università degli Studi di Firenze, INSTM Research Unit of Firenze, Via della Lastruccia n.3-13, 50019 Sesto Fiorentino, FI, Italy.
| | - Thierry Guizouarn
- Univ Rennes, INSA Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes), UMR 6226, Université de Rennes 1, F-35000 Rennes, France.
| | - Yan Suffren
- Univ Rennes, INSA Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes), UMR 6226, Université de Rennes 1, F-35000 Rennes, France.
| | - Guillaume Calvez
- Univ Rennes, INSA Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes), UMR 6226, Université de Rennes 1, F-35000 Rennes, France.
| | - Carole Daiguebonne
- Univ Rennes, INSA Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes), UMR 6226, Université de Rennes 1, F-35000 Rennes, France.
| | - Olivier Guillou
- Univ Rennes, INSA Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes), UMR 6226, Université de Rennes 1, F-35000 Rennes, France.
| | - Franck Artzner
- CNRS, IPR (Institut de Physique de Rennes), UMR 6251, Université de Rennes 1, F-35000 Rennes, France
| | - Matteo Mannini
- Dipartimento di Chimica "Ugo Schiff" (DICUS), Università degli Studi di Firenze, INSTM Research Unit of Firenze, Via della Lastruccia n.3-13, 50019 Sesto Fiorentino, FI, Italy.
| | - Kevin Bernot
- Univ Rennes, INSA Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes), UMR 6226, Université de Rennes 1, F-35000 Rennes, France.
- Institut Universitaire de France, 1 rue Descartes, 75005, Paris, France
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Lascialfari L, Pescitelli G, Brandi A, Mannini M, Berti D, Cicchi S. Urea vs. carbamate groups: a comparative study in a chiral C2 symmetric organogelator. SOFT MATTER 2015; 11:8333-8341. [PMID: 26350644 DOI: 10.1039/c5sm01684c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The effect of the replacement of molecular moieties (carbamates vs. urea) that drive self-assembly for two organogelators with an identical C(2) symmetric molecular structure is described. The main properties of the gels obtained from the urea-based organogelators are also discussed. The proposed organogelators are chiral molecules and are able to express chirality also at the supramolecular level, thus allowing the employment of electronic circular dichroism to gain insight into the molecular-scale structure of fibrillar aggregates. With the same technique, the behavior of enantiomeric mixtures of the urea-based organogelators was investigated, revealing the occurrence of different self-sorting phenomena at the molecular and supramolecular scale. The urea-based organogelators demonstrated to be more efficient gelators with respect to the carbamate-based analogues, showing a high gel-to-sol transition temperature (up to 66 °C) and a very low minimum gelling concentration (0.85 mg mL(-1)). This study is a starting point for a deeper investigation of structure/property relationships and, taking into account the peculiar behavior detected for the enantiomeric mixtures, also of self-sorting and molecular recognition phenomena.
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Affiliation(s)
- Luisa Lascialfari
- "Ugo Schiff" Chemistry Department, University of Florence, Via della Lastruccia 3-13, 50019, Sesto Fiorentino, Italy and INSTM Consortium, UdR Firenze, Via G. Giusti 9, 50121, Firenze, Italy
| | - Gennaro Pescitelli
- Department of Chemistry and Industrial Chemistry, University of Pisa, Via Moruzzi 13, 56124 Pisa, Italy
| | - Alberto Brandi
- "Ugo Schiff" Chemistry Department, University of Florence, Via della Lastruccia 3-13, 50019, Sesto Fiorentino, Italy and INSTM Consortium, UdR Firenze, Via G. Giusti 9, 50121, Firenze, Italy
| | - Matteo Mannini
- "Ugo Schiff" Chemistry Department, University of Florence, Via della Lastruccia 3-13, 50019, Sesto Fiorentino, Italy and INSTM Consortium, UdR Firenze, Via G. Giusti 9, 50121, Firenze, Italy
| | - Debora Berti
- "Ugo Schiff" Chemistry Department, University of Florence, Via della Lastruccia 3-13, 50019, Sesto Fiorentino, Italy and CSGI Consortium, UdR Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy
| | - Stefano Cicchi
- "Ugo Schiff" Chemistry Department, University of Florence, Via della Lastruccia 3-13, 50019, Sesto Fiorentino, Italy and INSTM Consortium, UdR Firenze, Via G. Giusti 9, 50121, Firenze, Italy
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Takemoto Y, Yamamoto T, Ikuma N, Uchida Y, Suzuki K, Shimono S, Takahashi H, Sato N, Oba Y, Inoue R, Sugiyama M, Tsue H, Kato T, Yamauchi J, Tamura R. Preparation, characterization and magnetic behavior of a spin-labelled physical hydrogel containing a chiral cyclic nitroxide radical unit fixed inside the gelator molecule. SOFT MATTER 2015; 11:5563-5570. [PMID: 26073537 DOI: 10.1039/c5sm01216c] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
An optically active amphiphilic nitroxide radical compound [(S,S,R)-], which contains a paramagnetic (2S,5S)-2,5-dimethyl-2,5-diphenylpyrrolidine-N-oxyl radical group fixed in the inner position together with a hydrophobic long alkyl chain and a hydrophilic (R)-alanine residue in the opposite terminal positions, was found to serve as a low-molecular-weight gelator in H2O to give rise to a spin-labelled physical hydrogel. Characterization of the hydrogel was performed by microscopic (SEM, TEM and AFM) techniques, XRD and SAXS measurements, and IR, UV and CD spectroscopies. The gel-sol transition temperature was determined by EPR spectral line-width (ΔHpp) analysis. Measurement of the temperature dependence of relative paramagnetic susceptibility (χrel) for the hydrogel and sol phases was achieved by means of the double-integration of VT-EPR spectra.
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Affiliation(s)
- Yusa Takemoto
- Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan.
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Caragheorgheopol A, Edwards W, Hardy JG, Smith DK, Chechik V. Using EPR spectroscopy as a unique probe of molecular-scale reorganization and solvation in self-assembled gel-phase materials. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:9210-9218. [PMID: 25017326 DOI: 10.1021/la501641q] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We describe the synthesis of spin-labeled bis-ureas which coassemble with bis-urea gelators and report on self-assembly as detected using electron paramagnetic resonance spectroscopy (EPR). Specifically, EPR detects the gel-sol transition and allows us to quantify how much spin-label is immobilized within the gel fibers and how much is present in mobile solvent pools-as controlled by temperature, gelator structure, and thermal history. EPR is also able to report on the initial self-assembly processes below the gelation threshold which are not macroscopically visible and appears to be more sensitive than NMR to intermediate-sized nongelating oligomeric species. By studying dilute solutions of gelator molecules and using either single or double spin-labels, EPR allows quantification of the initial steps of the hierarchical self-assembly process in terms of cooperativity and association constant. Finally, EPR enables us to estimate the degree of gel-fiber solvation by probing the distances between spin-labels. Comparison of experimental data against the predicted distances assuming the nanofibers are only composed of gelator molecules indicates a significant difference, which can be assigned to the presence of a quantifiable number of explicit solvent molecules. In summary, EPR provides unique data and yields powerful insight into how molecular-scale mobility and solvation impact on assembly of supramolecular gels.
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Affiliation(s)
- Agneta Caragheorgheopol
- Ilie Murgulescu Institute of Physical Chemistry, Romanian Academy , 202 Spl. Independentei, Bucharest 060021, Romania
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Lascialfari L, Berti D, Brandi A, Cicchi S, Mannini M, Pescitelli G, Procacci P. Chiral/ring closed vs. achiral/open chain triazine-based organogelators: induction and amplification of supramolecular chirality in organic gels. SOFT MATTER 2014; 10:3762-3770. [PMID: 24733431 DOI: 10.1039/c4sm00354c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The purpose of this study is to compare the gelling behavior of two molecules: a chiral compound and its achiral counterpart. The chiral partner is characterized by a rigid, chiral pyrrolidine nucleus, while the achiral one contains a flexible diethanolamine moiety. The chiral compound is an already known good organogelator, but also the achiral compound shows remarkable gelling properties. Very interestingly, a small fraction of the chiral compound induces chirality and strong CD effects in its aggregates with the achiral one. The observed chirality amplification corresponds to a peculiar sergeant-and-soldier effect. Molecular modelling and CD calculations suggested a model for the supramolecular assembly of hetero-aggregates that fits the experimental data.
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Affiliation(s)
- L Lascialfari
- Department of Chemistry, Università di Firenze, Via della lastruccia 3-13, 50019, Sesto Fiorentino-Fi, Italy.
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