Synthesis and Magnetic Studies of Quasi-Isotropic Coordination Compounds with 3d and 4f cations
[eng] The present Thesis is entitled “Synthesis and Magnetic Studies of Quasi-Isotropic Coordination Compounds with 3d and 4f cations”. The topic of the Thesis is to prepare coordination compounds of paramagnetic metal cations, either 3d or 4f, with Schiff base ligands, in order to study their magne...
| Autor: | |
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2023 |
| País: | España |
| Institución: | Universidad de Barcelona |
| Repositorio: | Dipòsit Digital de la UB |
| OAI Identifier: | oai:diposit.ub.edu:2445/202521 |
| Acceso en línea: | https://hdl.handle.net/2445/202521 http://hdl.handle.net/10803/689085 |
| Access Level: | acceso abierto |
| Palabra clave: | Magnetisme Compostos de coordinació Lantani Magnetism Coordination compounds Lanthanum |
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España |
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Synthesis and Magnetic Studies of Quasi-Isotropic Coordination Compounds with 3d and 4f cations |
| title |
Synthesis and Magnetic Studies of Quasi-Isotropic Coordination Compounds with 3d and 4f cations |
| spellingShingle |
Synthesis and Magnetic Studies of Quasi-Isotropic Coordination Compounds with 3d and 4f cations Pilichos, Evangelos Magnetisme Compostos de coordinació Lantani Magnetism Coordination compounds Lanthanum |
| title_short |
Synthesis and Magnetic Studies of Quasi-Isotropic Coordination Compounds with 3d and 4f cations |
| title_full |
Synthesis and Magnetic Studies of Quasi-Isotropic Coordination Compounds with 3d and 4f cations |
| title_fullStr |
Synthesis and Magnetic Studies of Quasi-Isotropic Coordination Compounds with 3d and 4f cations |
| title_full_unstemmed |
Synthesis and Magnetic Studies of Quasi-Isotropic Coordination Compounds with 3d and 4f cations |
| title_sort |
Synthesis and Magnetic Studies of Quasi-Isotropic Coordination Compounds with 3d and 4f cations |
| dc.creator.none.fl_str_mv |
Pilichos, Evangelos |
| author |
Pilichos, Evangelos |
| author_facet |
Pilichos, Evangelos |
| author_role |
author |
| dc.contributor.none.fl_str_mv |
Escuer Fité, Albert Mayans Ayats, Júlia Universitat de Barcelona. Departament de Química Inorgànica i Orgànica |
| dc.subject.none.fl_str_mv |
Magnetisme Compostos de coordinació Lantani Magnetism Coordination compounds Lanthanum |
| topic |
Magnetisme Compostos de coordinació Lantani Magnetism Coordination compounds Lanthanum |
| description |
[eng] The present Thesis is entitled “Synthesis and Magnetic Studies of Quasi-Isotropic Coordination Compounds with 3d and 4f cations”. The topic of the Thesis is to prepare coordination compounds of paramagnetic metal cations, either 3d or 4f, with Schiff base ligands, in order to study their magnetic properties and their slow relaxation of magnetization (SRM). The main characteristic of the compounds that show SRM is the presence of magnetic anisotropy, in the form D or axial zero-field splitting, which define the energy barrier that has to be overcome in order to have relaxation of magnetization. This Thesis provide experimental evidence that even if the parameter D can take low values, or even negligible, SRM can happen. This kind of systems belong the family of quasi-isotropic SMMs, because they have as building blocks metal cations that possess very small magnitude of D. The cations that have been chosen for this research are GdIII and MnII, which contain half- filled f and d orbitals, respectively. GdIII cannot present magnetic anisotropy due to its spherical electronic configuration; MnII has no crystal field stabilization energy, and thus, allowed us to tune its geometry. This fact, helped in order to prove that firstly, low magnetic anisotropy can play a pivotal role for the presence of SRM and secondly, that geometric distortions in cation’s environment are desired in order to observe relaxation of magnetization. Due to the fact that magnetic anisotropy takes very low values, classical magnetometry cannot give reliable results. Thus, Electronic Paramagnetic Resonance (EPR) measurements were carried out in order to define the axial and rhombic values of anisotropy. |
| publishDate |
2023 |
| dc.date.none.fl_str_mv |
2023 |
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info:eu-repo/semantics/doctoralThesis info:eu-repo/semantics/publishedVersion |
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doctoralThesis |
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publishedVersion |
| dc.identifier.none.fl_str_mv |
https://hdl.handle.net/2445/202521 http://hdl.handle.net/10803/689085 |
| url |
https://hdl.handle.net/2445/202521 http://hdl.handle.net/10803/689085 |
| dc.language.none.fl_str_mv |
Inglés |
| language_invalid_str_mv |
Inglés |
| dc.rights.none.fl_str_mv |
cc by-nc (c) Pilichos, Evangelos, 2023 http://creativecommons.org/licenses/by-nc/3.0/es/ info:eu-repo/semantics/openAccess |
| rights_invalid_str_mv |
cc by-nc (c) Pilichos, Evangelos, 2023 http://creativecommons.org/licenses/by-nc/3.0/es/ |
| eu_rights_str_mv |
openAccess |
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application/pdf |
| dc.publisher.none.fl_str_mv |
Universitat de Barcelona |
| publisher.none.fl_str_mv |
Universitat de Barcelona |
| dc.source.none.fl_str_mv |
Tesis Doctorals - Facultat - Química reponame:Dipòsit Digital de la UB instname:Universidad de Barcelona |
| instname_str |
Universidad de Barcelona |
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Dipòsit Digital de la UB |
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Dipòsit Digital de la UB |
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|
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|
| _version_ |
1869411756053364736 |
| spelling |
Synthesis and Magnetic Studies of Quasi-Isotropic Coordination Compounds with 3d and 4f cationsPilichos, EvangelosMagnetismeCompostos de coordinacióLantaniMagnetismCoordination compoundsLanthanum[eng] The present Thesis is entitled “Synthesis and Magnetic Studies of Quasi-Isotropic Coordination Compounds with 3d and 4f cations”. The topic of the Thesis is to prepare coordination compounds of paramagnetic metal cations, either 3d or 4f, with Schiff base ligands, in order to study their magnetic properties and their slow relaxation of magnetization (SRM). The main characteristic of the compounds that show SRM is the presence of magnetic anisotropy, in the form D or axial zero-field splitting, which define the energy barrier that has to be overcome in order to have relaxation of magnetization. This Thesis provide experimental evidence that even if the parameter D can take low values, or even negligible, SRM can happen. This kind of systems belong the family of quasi-isotropic SMMs, because they have as building blocks metal cations that possess very small magnitude of D. The cations that have been chosen for this research are GdIII and MnII, which contain half- filled f and d orbitals, respectively. GdIII cannot present magnetic anisotropy due to its spherical electronic configuration; MnII has no crystal field stabilization energy, and thus, allowed us to tune its geometry. This fact, helped in order to prove that firstly, low magnetic anisotropy can play a pivotal role for the presence of SRM and secondly, that geometric distortions in cation’s environment are desired in order to observe relaxation of magnetization. Due to the fact that magnetic anisotropy takes very low values, classical magnetometry cannot give reliable results. Thus, Electronic Paramagnetic Resonance (EPR) measurements were carried out in order to define the axial and rhombic values of anisotropy.[cat] La tesis doctoral “Synthesis and Magnetic Studies of QuasiIsotropic Coordination Compounds with 3d and 4f cations” ha estat duta a terme al laboratori de Magnetisme Molecular del Departament de Química Inorgànica i Orgànica de la Universitat de Barcelona. La present tesis doctoral estudia la coordinació de lligands tipus Base de Schiff a diferents cations paramagnètics per a estudiar els seu comportament magnetoquímica i la seva relaxació lenta de la magnetització (SMR). Tots els compostos que es presenten han estat sintetitzats, caracteritzats estructuralment i magnèticament. Un dels paradigmes de la relaxació lenta de la magnetització ha estat sempre la necessària existència d’una elevada anisotropia magnètica (parametritzada com a D o axial zero field splitting) de la quan en depèn la barrera d’energia potencial necessària per a presentar SMR. La present tesi doctoral, ajuda a demostrar que aquest paràmetre D pot ser gairebé negligible i dóna lloc al que hem anomenat quasi-isotropic slow relaxation, ja que els sistemes que aquí es discuteixen estan derivats de cations paramagnètics isotròpics (i per tant amb una D gairebé negligible) i tot i així presenten comportament SMR. Els cations escollits per a estudiar la propietat de relaxació lenta en sistemes isotròpics han estat els cations amb capes semiplenes com el MnII i GdIII. El GdIII presenta una distribució electrònica dels seus electrons f completament esfèrica i per tant sense possibilitat d’anisotropia, mentre que el MnII ha permès manipular la seva geometria i camp cristal·lí per demostrar que (i) a mida que s’augmenta la seva anisotropia mitjançant la introducció de diferents àtoms donadors en la seva esfera de coordinació va perdent caràcter de SMR i (ii) que a mida que augmenta la distorsió del seu entorn de coordinació també augmenta el seu caràcter SMR. Les mesures acurades del comportament SMR s’han realitzat amb SQUID. Degut a que aquesta classe de SMR no pot transcórrer a través de la barrera d’energia potencial, mesures específiques d’espectroscòpies d’ultra baixa freqüència han demostrat que, efectivament, els mecanismes de relaxació magnètica no transcorren a través d’una barrera energètica. L’anisotropia magnètica dels compostos s’ha mesurat mitjançant mesures d’EPR.Universitat de BarcelonaEscuer Fité, AlbertMayans Ayats, JúliaUniversitat de Barcelona. Departament de Química Inorgànica i Orgànica2023info:eu-repo/semantics/doctoralThesisinfo:eu-repo/semantics/publishedVersionapplication/pdfhttps://hdl.handle.net/2445/202521http://hdl.handle.net/10803/689085Tesis Doctorals - Facultat - Químicareponame:Dipòsit Digital de la UBinstname:Universidad de BarcelonaIngléscc by-nc (c) Pilichos, Evangelos, 2023http://creativecommons.org/licenses/by-nc/3.0/es/info:eu-repo/semantics/openAccessoai:diposit.ub.edu:2445/2025212026-05-27T06:46:51Z |
| score |
15.301603 |