Thèses sur le sujet « Spin crossover complexes »
Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres
Consultez les 50 meilleures thèses pour votre recherche sur le sujet « Spin crossover complexes ».
À côté de chaque source dans la liste de références il y a un bouton « Ajouter à la bibliographie ». Cliquez sur ce bouton, et nous générerons automatiquement la référence bibliographique pour la source choisie selon votre style de citation préféré : APA, MLA, Harvard, Vancouver, Chicago, etc.
Vous pouvez aussi télécharger le texte intégral de la publication scolaire au format pdf et consulter son résumé en ligne lorsque ces informations sont inclues dans les métadonnées.
Parcourez les thèses sur diverses disciplines et organisez correctement votre bibliographie.
Bergen, Elvira [Verfasser]. « Multifunctional Spin Crossover Complexes / Elvira Bergen ». Mainz : Universitätsbibliothek der Johannes Gutenberg-Universität Mainz, 2021. http://d-nb.info/1225796032/34.
Texte intégralTovee, Clare Anne. « Metal complexes exhibiting spin crossover and fluorescence ». Thesis, University of Leeds, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.509875.
Texte intégralSchlamp, Stephan [Verfasser], et Birgit [Akademischer Betreuer] Weber. « Amphiphilic Spin Crossover Complexes / Stephan Schlamp. Betreuer : Birgit Weber ». Bayreuth : Universität Bayreuth, 2014. http://d-nb.info/106001002X/34.
Texte intégralSung, Raymond Chi Wai. « ESR studies of some iron(II) spin crossover complexes ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0013/NQ52415.pdf.
Texte intégralSchlamp, Stephan Verfasser], et Birgit [Akademischer Betreuer] [Weber. « Amphiphilic Spin Crossover Complexes / Stephan Schlamp. Betreuer : Birgit Weber ». Bayreuth : Universität Bayreuth, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:703-epub-1718-4.
Texte intégralMohammed, Rufeida. « Iron complexes of new dipyrazolylpyridine derivatives for spin-crossover applications ». Thesis, University of Leeds, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.590300.
Texte intégralElhaik, JeÌroÌ‚me Ange. « Iron (II) spin crossover complexes of dipyrazolylpyridine and related ligands ». Thesis, University of Leeds, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.414161.
Texte intégralOuld, Moussa Nawel. « Photomagnetic properties of spin crossover complexes with multi-metastable states ». Toulouse 3, 2007. http://www.theses.fr/2007TOU30036.
Texte intégralThe aim of the present work was to develop a detailed picture of the photo-excitation process in some special spin crossover complexes, which exhibit more than one long-lived metastable states. We are interested in the effects of visible and infrared light irradiation on these systems. Such “multi-metastable spin crossover complexes” display actually an interesting and largely unexplored photophysics and hold also some promises as future candidates for storing and transferring information in molecular devices. In order to explore this topic, we have chosen five different systems: the mononuclear [Fe(ptz)6](BF4)2 complex (ptz = 1-propyleterazole) for which we demonstrate a clear decoupling between the crystallographic phase transition and the light-induced spin conversion and four binuclear complexes of the family {[Fe(L)(NCX)2]2bpym} (X = S or Se; L = bpym (2,2'-bipyrimidine) or bt (2,2'-bithiazoline)). This last study led to a number of original results, revealing for example wavelength-selective photomagnetic phenomena in these systems
Huxel, Timo [Verfasser], et Julia [Akademischer Betreuer] Klingele. « Low-melting cationic transition metal complexes : : developing spin crossover ionic liquids = Niedrigschmelzende kationische Übergangsmetallkomplexe : die Entwicklung von Spin Crossover Ionic Liquids ». Freiburg : Universität, 2014. http://d-nb.info/1123481598/34.
Texte intégralMarts, Amy Renae. « Magnetic Resonance Studies of Iron Spin Crossover Complexes and their Cobalt Analogs ». Miami University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=miami1385033230.
Texte intégralAndo, Hideo. « Molecular Insights into Spin Crossover Phenomena of 1st-Row Transition Metal Complexes ». 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/174958.
Texte intégralKyoto University (京都大学)
0048
新制・課程博士
博士(工学)
甲第17592号
工博第3751号
新制||工||1572(附属図書館)
30358
京都大学大学院工学研究科分子工学専攻
(主査)教授 佐藤 啓文, 教授 田中 一義, 教授 北川 進
学位規則第4条第1項該当
Djomgoue, Paul. « N3, N4/(N3S, N3O) and N6 Phenanthroline Bases and their Spin Crossover Iron(II) Complexes ». Doctoral thesis, Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-207498.
Texte intégralDie vorliegende Dissertation behandelt die Synthese von Eisen(II)-Komplexen und ihr spin crossover (SCO)-Verhalten. Das Gleichgewicht zwischen high-spin (HS)- und low-spin (LS)-Zustand verleiht den SCO-Systemen eine großes Anwendungspotential im Bereich der molekularen Elektronik. Dennoch existiert bis heute kein SCO-basiertes molekulares Bauteil auf dem Markt. Hauptgrund hierfür ist, dass die bislang bekannten SCO-Systeme keine hinreichenden Eigenschaften (z.B. TLIESST « 300 K) aufweisen. Das Ziel der vorliegenden Arbeit ist die Synthese neuer SCO-Verbindungen mit geeigneten Eigenschaften für die Anwendung. Zu Beginn der Arbeit werden die Komplexe [Fe(rac-22a)]2+∙2[BF4]– und [Fe(rac-22b)]2+ ∙2[BF4]– mit starren hexadentaten Liganden beschrieben. Entgegen der Erwartung verschiebt die N-Methylierung der Amine das Gleichgewicht in Richtung des LS-Zustandes. Verglichen mit dem nicht-methylierten Komplex Fe(rac-22b)]2+∙2[BF4]– zeigt Fe(rac-22a)]2+∙2[BF4]– eine höhere Übergangstemperatur T1/2, welche in Nitrobenzen 74 K und in Acetonitril 52 K beträgt. Für die Komplexe ist T1/2 lösungsmittelabhängig. Im Folgenden wurde die Ligandenserie 9-R2-2-(6-R1-pyridin-2-yl)-1,10-phenanthrolin mit den Vertretern 25b (R2= Me), 25f (R2 = Ph), 25d (R2 = C(O)H, 25c (R1 = Ph), 25l (R1 = oxyphenyl-4-oxymethylen), 25m (R1 = oxymesitylen) und 25j (R1 = pyrol-1-yl) hergestellt. Es wurde beobachtet, dass die Größe des Substituenten das SCO-Verhalten (T1/2) beeinflusst. Ergänzend wurde der Einfluss des Gegenions anhand der Komplexe [Fe(25c)]2+∙2[BF4]– und [Fe(25c)]2+∙2[B(Ph)4]– untersucht. Das Gegenion B(Ph)4– ermöglicht intra- und intermolekulare π···π-Wechselwirkungen in der Zelle, welche die Übergangstemperature T1/2 (200 K) gegenüber dem BF4–-Komplex (175 K) erhöhen. Des Weiteren beeinflussen die Substituenten R1 an der Pyridin-Einheit die ubergangskomplexes T1/2 stärker als die Substituenten R2 an der Phenanthrolin-Einheit. So ist [Fe(25f)]2+∙2[BF4]– (R1 = Ph) ein reiner HS-Komplex, während der Komplex [Fe(25c)]2+∙2[BF4]– (R2 = Ph) ein SCO-System ist (T1/2 = 175 K). Die Erhöhung der Koordinationszahl von N6 auf N8 wurde über die Synthese von tetradentaten Liganden untersucht. Diese Erhöhung führt zu einem unerwarteten Koordinationsmodus. So bildet [Fe(25i)]2+∙2[BF4]– (R2 = pyrazol-1-yl) eine quadratisch-antiprismatische Koordinationssphäre (HS Eisen(II)-Komplex) und zeigt, wie erwartet, über den untersuchten Temperaturbereich keine Fe–N-Bindungsspaltung
Alcover, Fortuny Gerard. « Spin-Crossover beyond the traditional Fe(II) complexes : ab initio study of spin-state stability in complexes with Mn, Ni and Ru ». Doctoral thesis, Universitat Rovira i Virgili, 2016. http://hdl.handle.net/10803/396293.
Texte intégralTradicionalmente el fenómeno de spin-crossover se ha estudiado en complejos hexacoordinados de Fe2+. El objetivo de esta tesis es profundizar en este fenómeno en complejos con metales de transición menos convencionales i otros números de coordinación mediante un estudio computacional. El capítulo 3 presenta el estudio de un compuesto de rutenio con capacidad de transferir electrones a moléculas aceptoras y por lo tanto con potenciales aplicaciones en celdas solares. En los capítulos 4 y 5 se analizan complejos de Ni porfirina con spin-crossover después de ser irradiados por luz. El capítulo 6 trata de los estados magnéticos y de oxidación de complejos de manganeso. El trabajo estudia las diferencias en la fotoquímica de estos metales con la de los complejos de hierro. El ejemplo de la porfirina de Ni funcionalizada con un brazo fenilazopiridínico aporta información sobre el mecanismo de spin-crossover dirigido por el ligando con cambio de coordinación. En los complejos de Mn, la estabilidad relativa de los estados singlete y triplete depende del carácter sigma-dador del ligando axial.
Spin-crossover phenomenon has traditionally been studied for hexacoordinated Fe2+ complexes. The aim of this thesis is to get insight on this phenomenon in less conventional transition metals and other coordination numbers by means of a computational study. Chapter 3 presents the study of a ruthenium compound with ability to transfer electrons to acceptor molecules and, hence, with potential applications in solar cells. Chapters 4 and 5 analyze Ni porphyrin complexes exhibiting spin-crossover after irradiation with light. Chapter 6 treats the magnetic and oxidation states of manganese complexes. The work studies the differences in the photochemistry of these metals with respect to the iron complexes. The example of Ni porphyrin functionalized with a phenilazopyridine arm helps to understand the mechanism of coordination-induced spin-crossover. In Mn complexes, the relative stability of the singlet and triplet states depends on the sigma-donor character of the axial ligand.
Hoyt, Jordan. « Synthesis and characterization of FE (II) spin crossover complexes containing the organic donor tetrathiafulvalene ». Tallahassee, Fla. : Florida State University, 2010. http://purl.fcla.edu/fsu/lib/digcoll/undergraduate/honors-theses/2181914.
Texte intégralAdvisor: Dr. Michael Shatruk, Florida State University, College of Arts and Sciences, Dept. of Chemistry and Biochemistry. Includes bibliographical references.
Davesne, Vincent. « Organic spintronics : an investigation on spin-crossover complexes from isolated molecules to the device ». Phd thesis, Université de Strasbourg, 2013. http://tel.archives-ouvertes.fr/tel-01062266.
Texte intégralNguyen, Luong-Lam. « Nanoparticles of molecular photoswitches based on spin-crossover fe(II) complexes with photoisomerizable ligands ». Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112267/document.
Texte intégralInvestigation of the iron(II) metal-centered spin-crossover core coordinate with photo-active ligands (tran / cis isomerization) and study of the ligand-driven light-induced spin change (LD-LISC) properties with functionalized iron(II) complexes in the form of nanoparticles dispersed in transparent thin films. For this investigation, we have selected a set of mononuclear complexes incorporating a bipyridine ligand substituted either with a methyl group (electronic and structural function) or a styryl group (photoactivable function). The introduction in the coordination sphere of three (strong ligand-field case) or two (intermediate ligand-field strength) bipyridine ligands (with NCSe- co-ligands) has allowed the modulation of the ligand-field strength experienced by the metal ion in different systems. Optical and thermal switching properties of solids have been investigated in polycrystalline powders and in dispersion of size-reduced objects (micro-, nano-particles).We have presented elaboration and study of micro- and nanoparticles, non-ionic mononuclear FeII complexes including bidentate ligand (4,4’-methyl-2,2’-bipyridine, Me2-bpy) have been selected. The synthesis of nano- and micro-objects has required the adaptation of the method (sudden precipitation in antisolvent). It was achieved with ionic [Fe(L)3](NCSe)2 precursors by playing with chemical equilibrium for inducing the precipitation of related neutral Fe(L)2(NCSe)2 species. Nano- and micro-crystals of Fe(Me2-bpy)2(NCSe)2 with sizes 56-1200 nm were characterized and then highly diluted in polymeric thin films for optimizing light absorption and investigating photoswitching processes. Fe(Me2-bpy)2(NCSe)2) in the form of nano-and micro-particles, processed in thin polymeric films were shown to exhibit thermal spin-crossover centered at temperatures higher than room temperature; no significant effect of environment was detected.We have studied the photochemical reactivity of the ionic precusors [Fe(msbpy)3](NCSe)2 (msbpy = trans- and cis-isomers of 4-methyl-4’-styryl-2,2’-bipyridine,) was first probed in solution. It has been established that the cis to trans isomerization of 4-methyl-4’-styryl-2,2’-bipyidine takes place in a quantitative way when the diamagnetic FeII complex was exposed to a blue light (405 nm); this reaction can be partly reversed with a UV excitation.We have elaborated spin-crossover nanoparticles based on the Fe(II) complexes are described; the switching of these particles (60nm) embedded in PMMA thin films and the LD-LISC effect are investigated. In the highly confined environment of nanoparticles, the FeII(t-msbpy)2(NCSe)2 complex also reacts upon irradiation. The combination of UV-Vis, Raman and photomagnetic measurements of the highly diluted materials has allowed us to analyze the effect of light irradiation and the spin-state switching behavior. The study of FeII(t-msbpy)2(NCSe)2 has shown the occurrence at room temperature of different processes depending on the excitation wavelength: a ligand-centered process (trans-to-cis isomerization, 365 nm) and a metal-centered one (resulting in a MLCT change, 405 nm)
Tong, Jin. « Homo- and Mixed-valence [2 × 2] Grid Complexes ». Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2016. http://hdl.handle.net/11858/00-1735-0000-0028-8736-B.
Texte intégralNieto, Castro David. « Advances in Spin Crossover : Synthesis, Mechanosynthesis and Switchable Multifunctional Hybrids ». Doctoral thesis, Universitat Rovira i Virgili, 2021. http://hdl.handle.net/10803/673157.
Texte intégralLos compuestos de “Spin crossover” (SCO) son materiales moleculares formados por iones metálicos con configuración electrónica d4d7 y ligandos que desdoblan los orbitales d. Dichos materiales poseen propiedades relevantes para aplicaciones prácticas, ya que son capaces de producir una transición de spin mediante un estímulo externo, como por ejemplo, un cambios en la temperatura o presión, irradiación de luz o mediante la aplicación de un campo magnético. Hasta la fecha, diferentes complejos de coordinación con distintos centros metálicos activos en SCO han sido sintetizados. Dentro de esta gran variedad de compuestos, los que tienen como centro activo Fe(II) han sido los mas estudiados ya que, en algunos casos, la transición de spin ocurre cerca de la temperatura ambiente, de forma abrupta, con histéresis y con gran estabilidad durante sucesivos ciclos. Estas características hacen que los compuestos de SCO basados en Fe(II) tengan relevancia para aplicaciones prácticas en electrónica molecular, dispositivos para almacenamiento de información, pantallas electrónicas o actuadores.En la presente tesis doctoral, se han desarrollado distintas estrategias dentro del campo de SCO.
Spin crossover (SCO) complexes are molecular materials with d4 d7 metal ions that possess a set of properties relevant for practical applications, since they are able to display a spin transition in response to external perturbation, such as a change of temperature, pressure, light irradiation or pulsed magnetic field. To date, many coordination SCO complexes have been studied with different metallic SCO active centres. Among the diverse variety of metal ions, Fe(II) has been the most studied one as, in some cases, the spin transition occurs abruptly, with hysteresis, close to room temperature and is stable over successive cycles. These features make Fe(II) SCO complexes suitable for relevant practical applications in molecular electronics, data storage, display devices, non-linear optics, and photomagnetism. In the present doctoral thesis, several approaches in the field of SCO have been performed.
Pittala, Narsimhulu. « Contribution to the Triazole-Based Fe(II) Spin-Crossover (SCO) materials : some achievements and new questions ». Thesis, Brest, 2016. http://www.theses.fr/2016BRES0084/document.
Texte intégralIn recent years, the spin-crossover (SCO) materials have attracted much interest because of their potential applications such as sensors or electronic displays; these complexes typically exhibit - via an external disturbance (e.g. temperature, radiation) - a reversible “High Spin (HS) Low Spin (LS)” spin transition. In this context, the present work has focused on the design and the magneto-structural investigations of single crystals of novel FeII SCO systems based on 4-R-1,2,4-triazole ligands including an alkyl spacer - with either (i) inorganic tetracyanometallates ([M(CN)4]2-, M = NiII, PtII, PdII) or (ii) specific organic cyanocarbanions ((tcnsR’)-: 1,1,3,3-tetracyano-2-thioalkylpropenide anions) - in order to ultimately understand the physicochemical origin of the strong cooperativity in such striking materials, but also to rationalize the tuning of the SCO properties. At first, a new 1D polymer [Fe(bntrz)3][Pt(CN)4].H2O (1) salt - exhibiting an abrupt spin transition and an exceptional resilience upon repeated switching - has been synthesized; the accurate single crystal investigations of both HS and LS states of the latter clearly revealed the impact of the longrange interactions on SCO properties in this system. Then, the substitution of the ‘rigid’ [Pt(CN)4]2- tetracyanometallate anion by the more ‘flexible’ (tcnset)- entity lead us to the first example of triazole-based SCO FeII trinuclear neutral complex [Fe3(bntrz)6(tcnset)6] (2) exhibiting a complete one-step spin transition above room temperature. The systematic variation of the R’ substituent from the functionalized (tcnsR’)- anion resulted in two new FeII SCO systems, i.e. the neutral trinuclear complex [Fe3(bntrz)6(tcnspr)6] (3) and the 1D [Fe3(bntrz)8(tcnsme)4](tcnsme)2.4H2O (4) derivative, with distinct structural characteristics and SCO behaviours. Finally, with the purpose to further evaluate the impact of different substituents at the 4th position onto 1,2,4-triazole ligand, two new 3D materials based on the functionalised triazole 2-(3-(4H-1,2,4-triazol-4-yl)propyl)isoindoline-1,3-dione (phtptrz) - {Fe3(μ2-phtptrz)6[μ2-Pt(CN)4]3}.C2H5OH,5.5H2O (5) and {Fe(phtptrz)[Pt(CN)4].H2O} (6) - have been synthesized and characterized; a two-step SCO behaviour is observed only in 5, while 6 shows a characteristic paramagnetic behavior
Reyes, Zuluaga Andres. « Modulation and tuning of spin crossover by encapsulation of metal complexes within halogen-bonded architectures ». Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/235893/1/Andres%2BReyes%2BZuluaga%2BThesis%283%29.pdf.
Texte intégralBrady, C. « Spectroscopy and kinetics of some iron (II) spin crossover complexes in solution and other media ». Thesis, Queen's University Belfast, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395450.
Texte intégralDiego, Creixenti Rosa. « Design, synthesis and study of coordination complexes with spin crossover or single-molecule magnet properties ». Doctoral thesis, Universitat de Barcelona, 2022. http://hdl.handle.net/10803/673305.
Texte intégralLos complejos de transición de espín (SCO) y los imanes moleculares (SMM) son prototipos prometedores que pueden alcanzar la biestabilidad magnética dentro de la escala molecular requerida para el almacenamiento de datos. A pesar de la extensa biblioteca de compuestos versátiles que exhiben estos comportamientos, actualmente, se siguen estudiando para comprender sus propiedades fundamentales. En esta tesis contribuimos en desvelar aspectos cruciales relacionadas con su fundamento magnético. A partir de la síntesis de derivados de 3-(bpp: 2-(pyrazol-1-yl)-6-(1H-pyrazol-3- yl)pyridine), se accedió a diversos compuestos mononucleares de Fe(II). El estudio magnético de estos compuestos ofrece una valiosa oportunidad para el análisis y comprensión de efectos específicos relacionados con el comportamiento de SCO en términos de: • Ajuste de la transición de SCO por diseño de ligando (capítulo 2) para la serie de complejos: [Fe(1,3-bpp)2](ClO4)2 (1), [Fe(met-1,3-bpp)2](ClO4)2 (2) y [Fe(dimet1,3-bpp)2] (ClO4)2 (3). • Estudio de los efectos cooperativos (capítulo 3) del complejo [Fe(met- 1,3bpp)2](ClO4)2 (2) usando los complejos isoestructurales [Zn(met1,3- bpp)2](ClO4)2 (4) y la serie de complejos [Fe1-xZnx(Me-1,3bpp)2](ClO4)2 (5x; 0.1, 0.153, 0.219, 0.333, 0.412, 0.476, 0.559 and 0.636). • Polimorfismo y estudio de la íntima relación entre los datos cristalográficos y magnéticos sobre una sucesión de transformaciones en estado sólido (Capítulo 4) del complejo [FeL(bpp)](ClO4)2 (6). El diseño de ligandos politópicos que contienen unidades pirazolil-piridina se analiza en el capítulo 5. Se sintetizaron y caracterizaron cinco nuevos ligandos orgánicos (H2L3-H2L7). También se propone una nueva ruta sintética prometedora para acceder a ligandos multitópicos, que permite obtener satisfactoriamente el ligando H2L8. A partir de estos ligandos se han sintetizado diversos tipos de compuestos supramoleculares con interesantes propiedades magnéticas: • [Co2(H2L)3]4+ (11) y [CoZn(H2L)3]4+ (13) para el estudio del comportamiento de SMM mediante 1H NMR paramagnético en solución (Capítulo 6). • Fe9O4(OH)10(H2L2)6(H2O)4](BF4)5 (17) y [Fe9O4Cl6(OH)8(H2L2)6]4(Cl) (18) con una estructura cuadriculada sin precedentes formada por el núcleo inorgánico, [Fe9O4(OH)8], sustentado por seis H2L2 ligandos (Capítulo 7). • Complejos binucleares de Fe(II), X@[Fe2(H2L)3]3+ (19-20) estudiados mediante el uso de espectroscopía de RMN paramagnética. Se presenta el primer intento en identificar la dinámica de sus estados de simetría-rota, [HS-LS] y [LS-HS]. Se obtuvieron nuevos compuestos dimerizados ([X@Fe(H2L5)3]2)3+ (24-27) atractivos para el estudió magnético en solución (Capítulo 8).
Fürmeyer, Fabian [Verfasser]. « Fe(II) and Co(II) Spin Crossover Complexes using 1,3,4 Thiadiazole Bridging Ligands / Fabian Fürmeyer ». Mainz : Universitätsbibliothek der Johannes Gutenberg-Universität Mainz, 2020. http://d-nb.info/1223054845/34.
Texte intégralKlimm, Ottokar [Verfasser], et Birgit [Akademischer Betreuer] Weber. « Nanostructuring of Fe(II) spin crossover complexes using block copolymer micelles / Ottokar Klimm ; Betreuer : Birgit Weber ». Bayreuth : Universität Bayreuth, 2020. http://d-nb.info/1205804765/34.
Texte intégralHoughton, Benjamin J. « The use of ligand field molecular mechanics and related tools in the design of novel spin crossover complexes ». Thesis, University of Warwick, 2015. http://wrap.warwick.ac.uk/72837/.
Texte intégralHunt, Sheri A. « Deuterium NMR spectroscopy of solid state electronically labile complexes : mixed valence iron triangles, iron (II) spin crossover complexes and horse heart cytochrome c / ». Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1997. http://wwwlib.umi.com/cr/ucsd/fullcit?p9804515.
Texte intégralLochenie, Charles [Verfasser], et Birgit [Akademischer Betreuer] Weber. « Spin Crossover Complexes : increasing cooperativity and adding fluorescence through extension of the π-system / Charles Lochenie ; Betreuer : Birgit Weber ». Bayreuth : Universität Bayreuth, 2016. http://d-nb.info/1121676197/34.
Texte intégralDavesne, Vincent [Verfasser], et W. [Akademischer Betreuer] Wulfhekel. « Organic spintronics : an investigation on spin-crossover complexes from isolated molecules to the device / Vincent Davesne. Betreuer : W. Wulfhekel ». Karlsruhe : KIT-Bibliothek, 2013. http://d-nb.info/1047383411/34.
Texte intégralSuleimanov, Iurii. « Nano-objets et nano-composites à transition de spin basés sur des complexes du fer(II) avec des ligands 1,2,4-triazoles ». Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30017.
Texte intégralThe thesis is devoted to the preparation of new nanoobjects and nanocomposites of spin crossover complexes [Fe(Htrz)2(trz)](BF4) and [Fe(NH2-trz)3](NO3)2 (where Htrz - 1,2,4-triazole, trz - 1,2,4-trazolato, NH2-trz - 4-amino-1,2,4-triazole) and investigation their properties. Nanoobjects of mixed-ligand complexes with different ratio of 4-amino-1,2,4-triazole to 1,2,4-triazole were synthesized in reverse emulsions. It was shown that the increasing of the of 4-amino-1,2,4-triazole quantity leads to the increasing of nanoparticles anisotropy while spin crossover temperatures decrease. Double-step spin transition was observed at 20% mol of 4-amino-1,2,4-triazole, while at concentrations over 50% mol. spin crossover properties of [Fe(Htrz)2(trz)](BF4) completely disappear. Investigations of their morpholgy, size and spin transition characteristics as well as investigations of mechanisms of the fluorescent properties change under the spin switching process are shown. We consider obtaining nanoobjects of mixed-ligand complexes of iron (II) based on 1,2,4-triazole and 4-amino-1,2,4-triazole. The ligands ratio influences the morphology, size and characteristics of the spin transition of nanoobjects obtained. New modification of the complex [Fe(NH2-trz)3](NO3)2 in the form of nanoobjects was obtained using ligand excess. High transition temperature of this form was evidenced by various methods of analysis. This form was found to be isostructural with a resolved structure of [Fe(NH2-trz)3](NO3)2 · 2H2O. Series of nanocomposites with plasmonic and luminescent properties were prepares. For the core-shell composite with gold nanoparticles higher efficiency of the spin state switching due to the photothermal effect was demonstrated in comparison to the control sample. Fluorescent spin crossover composites with quantum dots, organic luminophors and terbium complexes were described. For all these composites the luminescence intensity variation as a function of temperature have been found. The mechanisms responsable of the luminescence intensity variation at two spin state are discussed. These mechanisms include resonant energy transfer, mechanical strain and photon reabsorption. High photostability fort he terbium - spin crossover composite is demonstrated comparing to previously obtained similar spin crossover luminescetnt composites. An example of a practical application of obtained composites for manufacturing fluorescent thermosensitive paper is shown
Zhang, Yixin. « Design and Synthesis of a Series of Redox Active Tetrazine and Triazine Based Transition Metal Complexes ». Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37233.
Texte intégralPfrunder, Michael Craig. « Halogen bond mediated crystal engineering of metal complexes ». Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/71083/1/Michael_Pfrunder_Thesis.pdf.
Texte intégralRoberts, Thomas David. « Novel ligands based on 2,6-di(1H-pyrazol-5-yl)pyridine derivatives and applications in spin crossover and transfer hydrogenation complexes ». Thesis, University of Leeds, 2015. http://etheses.whiterose.ac.uk/9418/.
Texte intégralSchober, Anne. « Activation of Nitric Oxide and Dioxygen at Diferrous Complexes with Compartmental Pyrazolate Ligand Scaffolds ». Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2016. http://hdl.handle.net/11858/00-1735-0000-0023-3E09-E.
Texte intégralDolai, Ramapada [Verfasser], et Hans-Jörg [Akademischer Betreuer] Krüger. « Switching of Electronic States of Cobalt Dioxolene Complexes Triggered by Spin-Crossover Process and Valence Tautomerism / Ramapada Dolai ; Betreuer : Hans-Jörg Krüger ». Kaiserslautern : Technische Universität Kaiserslautern, 2020. http://d-nb.info/1204425434/34.
Texte intégralSaureu, Artesona Sergi. « From mononuclear to dinuclear : magnetic properties of transition metals complexes ». Doctoral thesis, Universitat Rovira i Virgili, 2016. http://hdl.handle.net/10803/386451.
Texte intégralEn las últimas décadas, el mundo de la tecnologia y el desarrollo de nuevos aparatos electrónicos se han convertido en vitales para nuestra sociedad. Considerando la creciente demanda para la interpretación de resultados experimentales, la mejora de los métodos teóricos y el crecimiento de los recursos computacionales nos han permitido un mejor entendimiento de los comportamientos magnéticos en los sistemas con metales de transición. El objetivo de esta tesis es contribuir a este campo de investigación con el estudio de materiales magnéticos usando herramientas computacionales (DFT, TD-DFT, CASSCF, CASPT2, DDCI, etc.), y en algunos casos, combinando con resultados experimentales. La primera parte (Capítulo 3 y 4) incluye el estudio de los estados electrónicos de los complejos de spin-crossover de Fe(II) y Fe(III) combinando la teoria funcional de la densidad (DFT y TD-DFT) con métodos multiconfiguracionales (CASSCF, CASPT2). Además, usando la misma combinación, hemos descrito el fenómeno LIESST en complejos de Fe(III). La segunda parte (Cap. 5 y 6) expone el estudio de las propiedades magnéticas asociadas al acoplamiento magnético utilizando metodos variacionales (DDCI, DDCI-2), en un complejo de Fe(IV) y un complejo bimetálico [MnCr]-oxalato, y como los cambios estructurales afectan a ese acoplamiento. Por otra parte, hemos hecho un riguroso analisis de la estructura electrónica del complejo de Fe(IV) para aportar la información para la descripción mas adecuada del sistema.
Over the last decades the world of technology and the development of new devices have become vital for our society. Considering the growing demand for interpretation of experimental observations, the improvement of theoretical methods and the increasing of the computational resources has allowed us to deepen the understanding of magnetic beahvior of metal transitions architectures. The aim of this thesis is to contribute to this research field with the study of magnetic materials by using computational tools (DFT, TD-DFT, CASSCF, CASPT2, DDCI, etc.), and in some cases combining it with experimental results. The first part (Chapters 3 and 4) includes the study of the electronic states of Fe(II) and Fe(III) spin-crossover complexes combining the density functional theory (DFT and TD-DFT) with multiconfigurational methodologies (CASSCF, CASPT2). In addition, we have described the LIESST phenomenon in Fe(III) using the same combination. The second part (Chapters 5 and 6) exposes the study of the magnetic properties related to the magnetic coupling using variational methods (DDCI, DDCI-2) of a Fe(IV) complex and bimetallic [MnCr] oxalate-based complexes and how changes can influence to the coupling. Moreover, a rigorous analysis of the electronic structure of the Fe(IV) system has been performed to provide more information about the most adequate description of the system in terms of intuitive chemical concepts.
Köhler, Christian [Verfasser]. « Spin crossover behavior of 1,3,4-oxadiazole based dinuclear iron(II) complexes und functionalized phosphonates as bridging ligands in inorganic-organic hybrid-materials / Christian Köhler ». Mainz : Universitätsbibliothek Mainz, 2016. http://d-nb.info/1105589935/34.
Texte intégralPetzold, Holm, Paul Djomgoue, Gerald Hörner, J. Matthäus Speck, Tobias Rüffer et Dieter Schaarschmidt. « 1H NMR spectroscopic elucidation in solution of the kinetics and thermodynamics of spin crossover for an exceptionally robust Fe2+ complex ». Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-210226.
Texte intégralDieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich
Djomgoue, Paul [Verfasser], Heinrich [Akademischer Betreuer] Lang, Heinrich [Gutachter] Lang et Birgit [Gutachter] Weber. « N3, N4/(N3S, N3O) and N6 Phenanthroline Bases and their Spin Crossover Iron(II) Complexes / Paul Djomgoue ; Gutachter : Heinrich Lang, Birgit Weber ; Betreuer : Heinrich Lang ». Chemnitz : Universitätsbibliothek Chemnitz, 2016. http://d-nb.info/1214377289/34.
Texte intégralGuo, Wenbin. « Nouveaux composés à conversion de spin et polymorphisme pour une approche multi-échelle vers les hautes T(LIESST) ». Thesis, Bordeaux, 2021. http://www.theses.fr/2021BORD0015.
Texte intégralThe Light-Induced Excited Spin-State Trapping effect (LIESST) appears as one of the most promising and exciting phenomena for applicative devices based on Spin-CrossOver (SCO) complexes. However, the fundamental understanding of the LIESST effect must be yet deeply completed prior to any rational design of any efficient material. For instance, it is still a great challenge to establish the structure-properties relationships corresponding to the LIESST process, though this approach is crucial to discover SCO materials with a high relaxation temperature T(LIESST). The target of this work is therefore to understand how to increase T(LIESST) towards a daily-life temperature range. We choose to reach this goal by increasing the distortion of the metal coordination sphere through two chemistry-based strategies: i) playing at the molecular scale via steric strains produced by halogen-substituted ligands and ii) controlling the molecular stress through polymorphism. Part I displays some fundamental knowledge on SCO and Part II and III are devoted to the synthesis, crystallography and (photo)magnetic studies of new molecular compounds, including polymorphs, of the [Fe(PM-L)2(NCX)2] family. First these new compounds offer a large panel of innovative behaviours, such as, for instance, negative or zero volume expansions at the SCO and the absence of multi-step transition despite independent metal sites within the crystal. This work enlarges significantly the richness of the SCO based perspectives. Second, the deep examination of the relevant parameters to high T(LIESST) as discussed in Part IV brings new features and, overall, definitively proves that all physical scales must be taken into account, leading to a multiscale concept of the LIESST effect
Kabalan, Lara. « Approches modélisatrices des propriétés magnétiques, spectroscopiques et de commutation de complexes moléculaires ». Phd thesis, Université Sciences et Technologies - Bordeaux I, 2010. http://tel.archives-ouvertes.fr/tel-00467811.
Texte intégralWu, Jianfang. « Theoretical study of the excited state lifetime by ligand modifications and the vibrational anharmonicity for Fe(II) and Ru(II) complexes ». Doctoral thesis, Universitat Rovira i Virgili, 2020. http://hdl.handle.net/10803/670776.
Texte intégralLos complejos de metales de transición se han popularizado debido a sus diferentes funcionalidades como materiales a escala nanoscopica. Aquellos que presentan entrecruzamiento de espín son especialmente interesantes por sus aplicaciones tecnológicas. Esta tesis describe alguno de los factores que gobiernan la temperatura de transición por entrecruzamiento de espín (T1/2) y la relajación de los estados excitados por el entrecruzamiento de espín inducido por luz. El primer capítulo se centra en las características electrónicas básicas i describe algunos detalles de las propiedades de los compuestos que van a ser estudiados posteriormente. Después de describir los métodos teóricos, en el capítulo 3 se investiga como la vida de los estados excitados puede ser controlada a través de los ligandos en los complejos [Fe(bpy)3]2+ y [Ru(bpy)3]2+. Se predijo que con el uso de ligandos menos sigma dadores, el tiempo de vida de los estados excitados podía crecer dos órdenes de magnitud en comparación con los complejos de referencia. En el capítulo 4, se ha puesto a prueba la capacidad de predicción de la diferencia de energía adiabática entre el estado de alto espín y el de bajo espín para un nuevo método computacional. Esta es una propiedad bastante difícil de calcular, y a pesar del esfuerzo realizado y la mayor precisión que debía presentar el método, no hemos sido capaces de presentar una alternativa viable a los métodos existentes, los cuales probablemente dan una respuesta correcta debido a una cancelación de errores. El último capítulo de investigación describe el efecto de la anharmonicidad vibracional en T1/2. Habitualmente, este efecto se considera muy pequeño, pero no ha estado comprobado. Nuestros resultados demuestran que la anharmonicidad cambia la temperatura de transición, a pesar de que el efecto es pequeño y otros efectos no introducidos en los cálculos teóricos deberían ser resueltos anteriormente.
Transition metal (TM) complexes have become popular as functional and tuneable nanoscale materials and those with spin-crossover (SCO) properties are especially interesting for technological applications. This thesis describes some of the factors that govern the transition temperature for spin-crossover (T1/2) and the excited state relaxation for light-induced SCO. The first chapter focusses on the basic features of the electronic structure and describes in some detail the properties of the compounds studied. After describing the theoretical methods, Chapter 3 explores how the excited state lifetime can be controlled by modifying the ligands in [Fe(bpy)3]2+ and [Ru(bpy)3]2+. Using weaker sigma donors in the Fe complex, the lifetime of the excited state was predicted to be two order of magnitude larger than in the parent compound. In chapter 4, a new and in principle more accurate computational method has been tested for its capacity to predict the HS-LS adiabatic energy difference. This is a notoriously difficult property to calculate and despite much effort, we have not been able to present an alternative to the yet existing methods, which are suspected to give the right answer because of a cancellation of errors. The last research chapter describes to what extent T1/2 is affected by neglecting vibrational anharmonicity. It is generally assumed to be small but this has never been tested. Our outcomes show that anharmonicity does change the transition temperature, but the effect is small and it is argued that other effects that are not taken into account in the theoretical treatments are much bigger and should be resolved first.
Lakhloufi, Sabine. « Investigation du mécanisme de la conversion de spin par diffraction des rayonnements (X et neutrons) : nouvelles approches ». Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENY063/document.
Texte intégralThis thesis suggests a new perspective on the study of the mechanism of spin conversion using the diffraction of X-rays and neutrons. This technique is implemented in an original way and leads to unprecedented results. Our work focuses on the pioneer exploration of spin conversion complexes by neutron diffraction, by obtaining structural films via multi-temperature X-ray diffraction and by the study of the crystalline quality over spin crossovers. The progress of this work relates to both the fundamental level, providing crucial information on the phenomenon of spin conversion, and the experimental level, opening new avenues of investigation. At the experimental level, the multi-structural study has led, through the acquisition of a considerable quantity of data, to the production of a spin-crossover film, allowing to visualize almost continuously all structural changes induced by the spin conversion. Fundamental results concern the switching mechanism from the atomic to the the crystal packing scale. The study of the crystal packing was also carried out by neutron diffraction, which allows the description of hydrogen bonds whose role, yet key in molecular materials, is nowadays only rarely studied in the spin crossover complex field. Finally, the crystalline fatigability in connection with the phenomenon of spin crossover has been addressed through an experimental protocol implemented in the laboratory. Applied to the evolution of a gradual spin crossover complex, this experimental approach has highlighted the crystal aging over conversion cycles, and makes a link between fatigability and macroscopic structure of the system
Gueddida, Saber. « Etude théorique de la transition de spin dans la molécule Fe(phen)2(NCS)2 adsorbée sur des surfaces métalliques ». Thesis, Strasbourg, 2014. http://www.theses.fr/2014STRAE013/document.
Texte intégralThe main objective of this PhD thesis is to use ab initio methods based on DFT to calculate and understand the mechanism of spin crossover phenomena in FePhen molecule adsorbed on a metallic substrate. We studied the structural, electronic and magnetic properties of the free and adsorbed FePhen molecule on a ferromagnetic metal substrate, such as cobalt, or a paramagnetic substrate such as gold or copper. We calculated the energy barrier required for the molecule to switch from low-spin to high-spin states using the ’Nudged Elastic Band’ (NEB) method. We also computed the ferromagnetic coupling between two magnetic layers, the magnetic FePhen molecule and the cobalt substrate according to the number of non-magnetic intermediate layer of copper. The focus is mainly on (1) the role played by van der Waals interactions, (2) the modeling of scanning tunneling microscopy (STM) and (3) the transport properties. We calculated the STM images using the Tersoff-Hamann approximation, which showed a good agreement with recent experimental STM images. We studied the transport properties of the adsorbed molecule FePhen on a metallic surface, using the Smeagol code which is based on the non-equilibrium Green’s function and Landauer formalism
Peng, Haonan. « Synthesis of spin crossover micro-and nano-particles and study of the effect of their sizes and morphologies on their bistability properties ». Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30082/document.
Texte intégralNowadays, the idea that molecule can be used as an active element in an electronic device stimulates scientific activity of chemistry and physics laboratories worldwide. The information storage capacity from technological demands is growing exponentially, which relies much on the development of nanosciences. The objective is to store data as quickly as possible in a device as small as possible. One of the most promising strategies is based on the concept of molecular bistability, the switching between two electronic states of a molecule in the same way that a binary switch. It is thus possible to pass in a reversible and detectable manner from one state (OFF = 0) to another state (ON = 1) under the influence of a controlled external stimulus. The spin transition (ST) phenomenon that switches the system between high spin (HS) and low spin (LS) states is a typical example of molecular bistability. The two states can be distinguished with different magnetic, optical and structural properties and can be induced by an external perturbation like the temperature, the light, the pressure, a magnetic field or the inclusion of a guest molecule. When the structural changes associated with the spin transition are transmitted in a cooperative manner across the network molecules, the transitions will occur with steepness and possibly accompanied by hysteresis loop (the first order transition). So, spin transition molecular materials should offer many opportunities in terms of applications in the field of electronics, information storage, digital display, photonics and photo-magnetism. Among the different families of compounds, coordination polymers arouse much interest due to their bistability near room temperature. The judicious choice of ligands and counter-anions make possible to modulate the final properties of these compounds and even in some cases to synergistically combine different physical properties. The work developed in this thesis attempt to address the different issues related to the challenge of coordination polymers based nanoscale materials with spin transition. The synthesis of inorganic bistable materials, their development in micro- and nanoparticles, thin layers, their organization and their physical properties are shown. The materials in the microscopic scale have mostly the same physical properties as those measured at the macroscopic scale. However, at the nanoscale, materials can exhibit physical properties that are far from those of bulk compounds. It is therefore imperative to understand more about the phenomena related to material size decrease to develop nanotechnology. The fundamental study of these nanomaterials is necessary and represents a major challenge today, which is of prime importance for the development of future applications. The development of nanoscale materials through the control of certain systematic models permits to improve our understanding of specific effects at the nanoscale. For example, in the case of spin crossover complex, the most important question is: how downsizing effect influences the transition temperature, the cooperativity and the width of hysteresis loop? In this context, this thesis is devoted to the design and the synthesis of various size spin crossover nano and micro-materials with different morphologies. To accomplish this, we developed the reverse-micelle technique and adopted innovative matrix-free synthetic approaches
Marmois, Emilie. « Étude photophysique de nouveaux systèmes moléculaires fonctionnels basés sur les styrylpyridines ». Thesis, Bordeaux 1, 2008. http://www.theses.fr/2008BOR13642/document.
Texte intégralThis Ph.D. work mainly deals with the study of fundamental photophysical processes of new styrylpyridine-type organic compounds showing charge transfer, realised using picosecond fluorescence and femtosecond transient absorption. We were interested first in the excited-state behaviour of two new hemicyanines. Methylated dimethoxystyrylpyridines molecules showed the establishment of an equilibrium between syn and anti conformations which is different in the excited state compared to the ground state, represented by a fast relaxation time of fluorescence. The second time constant corresponds to depopulation of the the excited state by non-radiative pathways as isomerization and donor twist (« loose-bolt »). Concerning styrylpyridinium derivative where phenyl group was replaced by dimethylaminothiophene, our studies proved involvment of rotation of methylpyridinium group and intersystem crossing as relaxation pathways. Secondly, we were interested in complexation properties of ether-crown susbstituted styrylpyridine molecule. Our studies showed the presence of two complexation centers (one in the center of the crown, the other one on the nitrogen of pyridine) having a different selectivity for metallic cations. Stoichiometries were confirmed by analysis of the reorientation times of formed complexes. After the study of our different compounds as elementary « building–blocks » for more complex supramolecular systems, we were interested in their potential applications with the study of systems for collection and energy transfer. First, we highlighted the existence of an ultra fast (180 fs to 6 ps) and ultra efficient (>99.7%) intramolecular energy transfer in bichromophoric systems containing two ether-crowned styrylpyridines and dissymetrised by binding of a Mg2+ cation in only one crown. It occurs from the complexed part to the non-complexed one by coulombic interaction. Another envisaged application can be the construction of complexes containing transition metals for energy or information storage. We studied first the building of a supramolecular system based on phenanthroline and containing four free ether-crowns We also proved that there exists an equilibrium between singlet and triplet excited states in these compounds complexed with Copper(I) or Silver(I). Secondly, we studied formation of complexes binding two ether-crown substituted bipyridines to a Fe2+ ion. Such a complex has got some spin crossover properties. Then, we showed that the addition of Ba2+ ions induce formation of transition metals complexes with nanometric size
Squillantini, Lorenzo. « Spin Crossover complexes : from synthesis to surface assembly ». Doctoral thesis, 2021. http://hdl.handle.net/2158/1235501.
Texte intégralLiu, Chi-Tsun, et 劉啟村. « Syntheses and characterization of atr base Fe(Ⅱ) spin crossover complexes ». Thesis, 2005. http://ndltd.ncl.edu.tw/handle/96657537180360809788.
Texte intégral國立臺灣大學
化學研究所
93
A new ligand, trans-4,4`-azo-1,2,4-triazole (atr) was designed and synthesized to construct the possible candidates for spin crossover system. The ligand is a planar molecule with two 1,2,4-triazole linked by an azo group. It could be served as a multi-dentate ligand or a good linkage ligand. A series of Fe(II) polymeric compounds in 1D, 2D and 3D frameworks have been successfully synthesized and studied structurally and magnetically. The crystal structures of the ligand and the series of polymeric Fe(II) complexes will be presented. In all the complexes, each ligand atr serves as a bridge between two Fe(II) centers; There are water molecules and NCS ligand around each Fe(II) in the 1-D polymeric compound, [Fe(µ-atr)(NCS)2(H2O)2]; An additional bridge ligand,pyz, is used to form a rectangular 2D framework, [Fe(µ-atr)(µ-pyz)(NCS)2].4H2O. A cationic species with Fe to atr ratio of 1 to 3 is formed in a 3D framework with the perchlorate as the inclusion counter anions,[Fe(µ-atr)3](ClO4)2.2H2O, the structure shows a interlock network. The magnetic properties are quite interesting: It is ferromagnetic for the 1D system but display spin transitions for both 2D and 3D systems. It exhibits an abrupt spin transition at Tc= 227 K for [Fe(µ-atr)(µ-pyz)(NCS)2].4H2O. However, it shows a two-step spin transition for the 3D frameworks [Fe(µ-atr)3](ClO4)2.2H2O. The crystal structures at various spin states will be compared.
wang, Ling-phone, et 王棱峰. « The synthesis and magnetic properties of Fe(II) spin-crossover complexes ». Thesis, 2002. http://ndltd.ncl.edu.tw/handle/n5572h.
Texte intégral國立成功大學
化學系碩博士班
90
The synthesis and magnetic properties of ferrous complexes �杚e(C6H8N2)2(NCS)2�� (1), �杚e(C6H8N2)2(NCSe)2�� (2), �杚e(C7H10N2)2 (NCS)2�� (3), �杚e(C7H10N2)2 (NCSe)2?(4), �杚e(C12H14N4)(NCS)2��•1/4 C2H5OH (5), �杚e(C25H24N4)(NCS)2��•C2H5OH (6) and �杚e(C6H8N2)2 (CH3COO)2�� (7) are reported. The magnetic susceptibilities are measured from 2 K to 300 K for all complexes. Complexes 1, 2, 3 and 4 show spin crossover (S = 2 ?S = 0) behaviors and complexes 5, 6 and 7 are high spin (S = 2). The magnetic behaviors of these complexes are influenced by the replacement of atom or the change and modifiaction of ligands.
Guo, Huan. « Novel Iron(II) Triazole-Pyridine Based Dinuclear Complexes : Synthesis, Characterization And Magnetic Properties ». Thesis, 2013. http://hdl.handle.net/1974/8302.
Texte intégralThesis (Master, Chemistry) -- Queen's University, 2013-09-20 10:34:02.756
Djomgoue, Paul. « N3, N4/(N3S, N3O) and N6 Phenanthroline Bases and their Spin Crossover Iron(II) Complexes ». Doctoral thesis, 2015. https://monarch.qucosa.de/id/qucosa%3A20526.
Texte intégralDie vorliegende Dissertation behandelt die Synthese von Eisen(II)-Komplexen und ihr spin crossover (SCO)-Verhalten. Das Gleichgewicht zwischen high-spin (HS)- und low-spin (LS)-Zustand verleiht den SCO-Systemen eine großes Anwendungspotential im Bereich der molekularen Elektronik. Dennoch existiert bis heute kein SCO-basiertes molekulares Bauteil auf dem Markt. Hauptgrund hierfür ist, dass die bislang bekannten SCO-Systeme keine hinreichenden Eigenschaften (z.B. TLIESST « 300 K) aufweisen. Das Ziel der vorliegenden Arbeit ist die Synthese neuer SCO-Verbindungen mit geeigneten Eigenschaften für die Anwendung. Zu Beginn der Arbeit werden die Komplexe [Fe(rac-22a)]2+∙2[BF4]– und [Fe(rac-22b)]2+ ∙2[BF4]– mit starren hexadentaten Liganden beschrieben. Entgegen der Erwartung verschiebt die N-Methylierung der Amine das Gleichgewicht in Richtung des LS-Zustandes. Verglichen mit dem nicht-methylierten Komplex Fe(rac-22b)]2+∙2[BF4]– zeigt Fe(rac-22a)]2+∙2[BF4]– eine höhere Übergangstemperatur T1/2, welche in Nitrobenzen 74 K und in Acetonitril 52 K beträgt. Für die Komplexe ist T1/2 lösungsmittelabhängig. Im Folgenden wurde die Ligandenserie 9-R2-2-(6-R1-pyridin-2-yl)-1,10-phenanthrolin mit den Vertretern 25b (R2= Me), 25f (R2 = Ph), 25d (R2 = C(O)H, 25c (R1 = Ph), 25l (R1 = oxyphenyl-4-oxymethylen), 25m (R1 = oxymesitylen) und 25j (R1 = pyrol-1-yl) hergestellt. Es wurde beobachtet, dass die Größe des Substituenten das SCO-Verhalten (T1/2) beeinflusst. Ergänzend wurde der Einfluss des Gegenions anhand der Komplexe [Fe(25c)]2+∙2[BF4]– und [Fe(25c)]2+∙2[B(Ph)4]– untersucht. Das Gegenion B(Ph)4– ermöglicht intra- und intermolekulare π···π-Wechselwirkungen in der Zelle, welche die Übergangstemperature T1/2 (200 K) gegenüber dem BF4–-Komplex (175 K) erhöhen. Des Weiteren beeinflussen die Substituenten R1 an der Pyridin-Einheit die ubergangskomplexes T1/2 stärker als die Substituenten R2 an der Phenanthrolin-Einheit. So ist [Fe(25f)]2+∙2[BF4]– (R1 = Ph) ein reiner HS-Komplex, während der Komplex [Fe(25c)]2+∙2[BF4]– (R2 = Ph) ein SCO-System ist (T1/2 = 175 K). Die Erhöhung der Koordinationszahl von N6 auf N8 wurde über die Synthese von tetradentaten Liganden untersucht. Diese Erhöhung führt zu einem unerwarteten Koordinationsmodus. So bildet [Fe(25i)]2+∙2[BF4]– (R2 = pyrazol-1-yl) eine quadratisch-antiprismatische Koordinationssphäre (HS Eisen(II)-Komplex) und zeigt, wie erwartet, über den untersuchten Temperaturbereich keine Fe–N-Bindungsspaltung.