Academic literature on the topic '4f complexes'
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Journal articles on the topic "4f complexes"
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Miao, Hao, Hong-Qing Li, Fu-Xing Shen, Hai-Yan Wei, Bao-Lin Wang, and Xin-Yi Wang. "A family of lanthanide complexes with a bis-tridentate nitronyl nitroxide radical: syntheses, structures and magnetic properties." Dalton Transactions 48, no. 27 (2019): 10337–45. http://dx.doi.org/10.1039/c9dt01397k.
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Costes, Jean-Pierre, Ghenadie Novitchi, and Colette Lebrun. "Synthesis and characterization of new heterodinuclear (4f, 4f′) lanthanide complexes." Journal of Alloys and Compounds 374, no. 1-2 (July 2004): 377–81. http://dx.doi.org/10.1016/j.jallcom.2003.11.025.
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Andruh, Marius. "Binuclear complexes as tectons in designing supramolecular solid-state architectures." Pure and Applied Chemistry 77, no. 10 (January 1, 2005): 1685–706. http://dx.doi.org/10.1351/pac200577101685.
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Oligonuclear complexes as well as coordination polymers with various network topologies can be obtained by using homo- or heterobinuclear complexes as starting materials. These building blocks are stable complexes, where the metal ions are held together by compartmental ligands, or alkoxo-bridged Cu(II) species. The binuclear nodes can be connected through appropriate exo-dentate ligands, or through metal-containing anions (e.g., [M(CN)6]3-, M = CrIII, FeIII, CoIII). A rich variety of 3d-3d and 3d-4f heterometallic complexes, with interesting architectures and topologies of the spin carriers, has been obtained. A particular case is the one concerning the 3d-4f binuclear nodes. Following this strategy, we were able to obtain coordination polymers containing three different spin carriers (2p-3d-4f; 3d-3d'-4f).
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Abdus SUBHAN, Md, Takayoshi Suzuki, and Sumio Kaizaki. "Laser Emission in 4f-4f Transitions of Some Nd(III) Complexes." Molecular Crystals and Liquid Crystals 379, no. 1 (January 1, 2002): 395–400. http://dx.doi.org/10.1080/713738671.
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Iftikhar, K. "Hypersensitivity in the 4f–4f absorption spectra of lanthanide(III) complexes." Inorganica Chimica Acta 129, no. 2 (June 1987): 261–64. http://dx.doi.org/10.1016/s0020-1693(00)86672-4.
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KOROVIN, YU, Z. ZHILINA, N. RUSAKOVA, V. KUZ'MIN, S. VODZINSKY, and YU ISHKOV. "Spectral-luminescent effects in heterometallic complexes of crown-porphyrins." Journal of Porphyrins and Phthalocyanines 05, no. 05 (May 2001): 481–85. http://dx.doi.org/10.1002/jpp.350.
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New complexes of ytterbium with porphyrins containing crown- and other oxygen-containing cyclic substituents were obtained. The absorption, excitation, ligand luminescence and 4f-luminescence spectra have been investigated. It has been shown that 4f-luminescence of ytterbium Yb ( III ) ions was a result of the intramolecular energy transfer from the triplet level of the ligands to the resonance 2F5/2 level of Yb ( III ). It has been also established that in presence of alkali metal Na , K and Cs the dimer complexes (sandwich-type) of ytterbium-crown-porphyrin were formed. Molecular luminescence of the porphyrin matrix was quenched completely in these dimers, but at the same time the quantum yield and lifetime of 4f-luminescence increase in the complexes.
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Visinescu, Diana, Maria-Gabriela Alexandru, Augustin M. Madalan, Ie-Rang Jeon, Corine Mathonière, Rodolphe Clérac, and Marius Andruh. "A new family of [CuIILnIIIMV] heterotrimetallic complexes (Ln = La, Gd, Tb; M = Mo, W): model systems to probe exchange interactions and single-molecule magnet properties." Dalton Transactions 45, no. 18 (2016): 7642–49. http://dx.doi.org/10.1039/c6dt00614k.
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Four 3d–4f–4(5)d heterotrimetallic complexes, [L2CuLn(H2O)5(μ-NC)M(CN)7], were obtained from the association of the binuclear 3d–4f complexes and {MV(CN)8}3− metalloligands.
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Rohini, Rohini, Minati Baral, and B. K. Kanungo. "Comparative studies of the electronic, binding and photophysical properties of a new nona-dentate hemi-cage tripodal HQ pendant trizaza-macrocycle with unfilled, half-filled and completely filled lanthanide ions." New Journal of Chemistry 42, no. 19 (2018): 16040–59. http://dx.doi.org/10.1039/c8nj02217h.
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The present paper describes the comparative studies of the electronic, photophysical and binding properties of a new C3-symmetric polydentate ligand and its complexes with 4f0, 4f7, and 4f14 metal ions (La3+, Gd3+, and Lu3+).
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Smola, Sergiy, Natalya Rusakova, Elena Martsinko, Inna Seifullina, and Yuriy Korovin. "Spectroscopic Properties of the Ln-Ge Complexes with Diethylenetriaminepentaacetic Acid." Chemistry Journal of Moldova 2, no. 1 (December 2007): 83–87. http://dx.doi.org/10.19261/cjm.2007.02(1).10.
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Four new heteronuclear lanthanide complexes with general formula [Ge(OH)(μ-HDTPA)LnGe(OH) (μ-DTPA)] (Ln = Sm – Dy) were synthesized and subsequently characterized by different physico- chemical methods. The structures of new compounds have been proposed. In considered complexes the 4f-luminescence of three-charged ions of samarium, europium, terbium and dysprosium is realized at UV-excitation. It is noteworthy that it is the first observation of 4f-luminescence in water solutions of heteronuclear f-p-complexes. The comparison of luminescent characteristics of hetero- and homonuclear landthanide complexes is described and discussed as well.
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Costisor,, Otilia, and Wolfgang Linert,. "On Polynuclear Complexes in 3d-4f System." Reviews in Inorganic Chemistry 25, no. 1 (January 2005): 13–54. http://dx.doi.org/10.1515/revic.2005.25.1.13.
Full textDissertations / Theses on the topic "4f complexes"
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DUPUIS, ARNAUD. "Etude systematique des complexes heterodinucleaires 3d-4f et 4f-4f : voies generales de synthese, structures et proprietes magnetiques cooperatives." Toulouse 3, 1998. http://www.theses.fr/1998TOU30084.
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Le but ultime de ce travail concerne l'etude des proprietes magnetiques cooperatives de complexes heterodinucleaires 3d-4f et 4f-4f'. Dans une premiere partie, nous decrivons plusieurs voies generales de synthese donnant acces a des familles de complexes heterodinucleaires associant un element 3d et un element 4f ou deux elements 4f differents. Les strategies de synthese reposent sur l'utilisation de ligands bicompartimentes permettant de coordonner successivement et selectivement un premier element 3d ou 4f, puis un second element 4f. En dehors des ligands symetriques classiques, nous elaborons egalement des methodes de preparation de ligands dissymetriques originaux, a partir de demi-unites ligand ou complexe, grace auxquels les deux centres metalliques sont relies par deux ponts differents (cetonique, phenolate ou oximate). Nos travaux conduisent a l'obtention et a la caracterisation complete des premiers complexes strictement dinucleaires 3d-4f et 4f-4f' avec les ions cu#2#+, vo#2#+, ni#2#+#b#a#s# #s#p#i#n, ni#2#+#h#a#u#t# #s#p#i#n, co#2#+#h#a#u#t# #s#p#i#n ou fe#3#+#h#a#u#t# #s#p#i#n comme element 3d et un des ions ln#3#+ comme element 4f. Dans la deuxieme partie, nous etudions les proprietes magnetiques des complexes 3d-4f et 4f-4f' obtenus. Lorsque les ions mis en jeu ne possedent qu'un moment purement de spin, nous etablissons sans ambiguite, a partir d'une analyse theorique, a la fois la nature et l'intensite des couplages magnetiques. Dans le cas ou l'un au moins des moments comprend une contribution orbitalaire, nous demontrons qu'une etude empirique permet de definir la nature de l'interaction. Tous les resultats obtenus sont originaux et peuvent se resumer ainsi : lorsque les deux centres metalliques sont relies par des ponts phenolates, _ le couplage mgd#3#+ est ferromagnetique avec m = cu#2#+, vo#2#+, ni#2#+#h#a#u#t# #s#p#i#n, co#2#+#h#s, fe#3#+#h#s, _ le couplage cu#2#+ln#3#+ est ferromagnetique pour ln = tb, dy, ho, er, _ le couplage cu#2#+ln#3#+ est antiferromagnetique pour ln = ce, nd, sm, tm, yb, _ le couplage cu#2#+ln#3#+ est nul pour ln = eu et pr (sous certaines conditions de champ cristallin), alors que lorsque l'un des deux ponts est un pont oximate, le couplage cu#2#+gd#3#+ peut etre antiferromagnetique.
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André, Nicolas. "Des complexes monométalliques 4f aux hélicates hétérodimétalliques 4f-4f' par reconnaissance spécifique ligand-cation lanthanide : synthèse, structure, stabilité et propriétés photophysiques /." Lausanne, 2002. http://library.epfl.ch/theses/?nr=2607.
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BAUX, CHRISTOPHE. "Synthese de materiaux moleculaires a base de lanthanides : de l'oxygene au soufre, vers une augmentation des interactions magnetiques dans les complexes 4f/4f et 4f/3d." Rennes, INSA, 2001. http://www.theses.fr/2001ISAR0015.
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Le travail presente s'inscrit dans le domaine de l'etude du magnetisme moleculaire et a consiste a degager des voies de synthese donnant acces a des complexes de terres rares a ponts soufres. Le but est de verifier que le remplacement des atomes d'oxygene donneurs (orbitales de valence 2p) des ligands par des atomes de soufre donneurs (orbitales de valence 3p) conduit bien a une augmentation du couplage magnetique entre les centres metalliques (ici, des ions lanthanides). Une premiere partie, bibliographique, presente ̱le magnetisme depuis sa decouverte jusqu'a l'emergence du magnetisme moleculaire ̱les elements 4f et leurs proprietes tant physiques que chimiques ̱les chalcogenures de lanthanides existants. La seconde partie, quant a elle, presente ̱la theorie hsab de pearson - et son application a la chimie des terres rares - qui a permis de determiner les conditions d'obtention de complexes soufres des terres rares en milieu organique a temperature ambiante ̱le ligand tetrathiooxalato et les tetrathiooxalates de terres rares auxquels il a conduit. Ces complexes, sont a notre connaissance, les premiers exemples de composes ou deux ions lanthanides sont en interaction magnetique a travers un pont de type dithiolene.
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Feuersenger, Jürgen. "Synthesis and characterisation of 3d-4f-complexes and their magnetic properties." Thesis, Bordeaux 1, 2010. http://www.theses.fr/2010BOR14195/document.
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Ce travail de thèse décrit (i) la synthèse de complexes hétérométalliques d’ions 3d et 4f à partir de précuseurs de Mn, Fe et Co, de sels de lanthanides et de ligands organiques et (ii) l'étude de leurs structures et propriétés. 41 complexes polynucléaires ont été synthétisés dans le cadre de ce travail. Les structures moléculaires de tous les composés ont été déterminées par diffraction des rayons X. Les propriétés magnétiques de 22 complexes ont été étudiées, dont quatre montrent une relaxation lente de leur aimantation considérée comme la signature d’un comportement de molécule-aimant. L'activité catalytique du complexe {Mn4Dy6Li2} calciné a aussi été étudiée et s'est avérée efficace pour l'oxydation du monoxyde de carbone. L'étude systématique de complexes isostructuraux de lanthanides a montré que l'incorporation d’ions 4f peut introduire de l’anisotropie magnétique et que l’ion DyIII est généralement le meilleur candidat pour le ciblage de molécules-aimants hétérométalliques 3d- 4fThis dissertation describes the syntheses of 3d-4f-metal complexes starting from preformed compounds of Mn, Fe and Co, lanthanide salts and organic ligands and also the investigation of their structures and properties. 41 new polynuclear heterometallic metal complexes were synthesised in the course of this work with different interesting properties. The structures of all obtained compounds have been confirmed using X-ray diffraction. The magnetic properties of 22 complexes were studied, of which four show frequency dependent out-of-phase signals as expected for SMMs. The catalytic activity of calcinated {Mn4Dy6Li2} was investigated and proved effective for the oxidation of CO. It was established, that the use of precursors leads to new families of compounds. Moreover the study of isostructural compounds across the lanthanide series showed 1) that the incorporation of 4f ions introduces magnetic anisotropy and 2) DyIII is usually the best candidate for targeting 3d-4f-SMMs
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Alves, Lemes Maykon. "Magnetic Exchange Coupling in 3d and 4f Complexes Using Radical Tetrazine-based Frameworks." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39598.
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High symmetry and low coordinated single-ion lanthanides have been a successful recipe to design high performance single molecule magnets (SMMs). However, enhancement of the magnetic properties of polymetallic SMMs is an important challenge. Therefore, this thesis describes the use of redox non-innocent tetrazine-based ligands and d- and f- elements in order to fine-tune the electronic structure of the resulting compounds to promote strong exchange interactions between the spin carriers. As reported in the literature, radical-bridged ligands represent a potential strategy to improve the magnetic properties of polymetallic SMMs. Thus, chapter one introduces principal concepts that govern the physical properties of metal complexes containing radical-bridged ligands.
Chapter two describes the magnetic properties of a unique air-stable tetratopic radical- bridged bpymtz•− (3,6-bis(2-pyrimidyl)-1,2,4,5-tetrazine) templating four Ni(II) metal ions. The dc magnetic studies along with DFT calculations reveal strong ferromagnetic exchange coupling between the Ni− bpymtz•− of J = 98 cm-1 with a spin ground state of S = 9/2.
Chapter three describes the application of another tetrazine-based ligand, bpytz (3,6- bis(3,5-dimethylpyrazolyl)-1,2,4,5-tetrazine) to probe magnetic exchange interactions in a {CoII4} supramolecular square. The modelling of dc susceptibility data shows significant Co(II) - bpytz•− magnetic coupling of J = - 118 cm-1 for a spin ground state ST = 4. While the non-reduced analog displays weak Co(II)-Co(II) exchange of J = - 0.64 cm-1 (S = 0 ground state). Additionally, the radical-radical magnetic exchange contribution was probed with an analogous {ZnII4} square, where a J = -15.9 cm-1 was found.
Chapter four extends the application of reduced tetrazine ligands to lanthanide systems. Here we demonstrate that the systematic reduction of the ligand with cobaltacene (CoCp2) led to the formation of a strongly coupled bpytz•−−bpytz•− bridging ligand. Magnetic measurements combined with ab initio calculations confirm unprecedented intramolecular pi-dimerization preventing strong magnetic Dy(III)−bpytz•− communication.
Chapter five describes the synthesis and characterization of {LnIII4} (Ln = Dy, Gd and Lu) where the Ln(III) ions are bridged by peripheral bpytz•−. The oxophilicity and high coordination numbers preferred by lanthanides ions lead to the formation of a cubane core made up of metal ions bridged by hydroxy ligands (M3-OH−). Experimental and computational studies were applied to verify the nature and strength of the magnetic interactions between the spin carriers.
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Griffiths, Kieran. "Catalytic and topological aspects of Schiff base supported 3d-4f polynuclear coordination complexes." Thesis, University of Sussex, 2018. http://sro.sussex.ac.uk/id/eprint/75278/.
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The work presented in this thesis deals with the employment of Schiff base ligands used to synthesise novel 3d-4f polynuclear coordination clusters (PCCs) and the investigation into their potential magnetic, luminescent and catalytic properties. Chapter one provides a general introduction to the chemistry described in the thesis. It includes a general overview of 3d-4f PCC chemistry and the applications of these materials and previous synthetic strategies for the preparation of Schiff base PCCs. A rationale is presented for the ligands employed in the thesis and a synthetic strategy is devised for the synthesis of specific materials. The initial chapters are focused on the synthesis of 3d-4f PCCs with novel core topologies and the study of their magnetic properties. Several novel series of 3d-4f PCCs are presented with unique core topologies which are previously unobserved in 3d-4f PCC chemistry. In addition, some of the presented PCCs display single-molecule magnet (SMM) properties or a significant magnetocaloric effect (MCE). Chapter five bridges synthetic aspects discussed in the previous chapters, with a synthetic study targeting 3d-4f PCCs with a defect dicubane core (2,3M4-1) and introduces the term “isoskeletal” to describe PCCs which possess the same topology or related organic structures with the same host framework but different guests. Chapters seven to nine are focused on the development of a well characterised isoskeletal family of 3d-4f PCCs with a defect dicubane core and the investigation of their potential catalytic properties in a range of organic reactions including Michael Addition, Friedel-Crafts alkylations and multicomponent reactions. Characterisation of the 3d-4f PCCs is emphasised and verifies the stability of the 2,3M4-1 core in solution. An attempt at understanding the catalytic system and mechanistic aspects is undertaken, which is not explored in previously reported 3d-4f PCC co-operative catalysis. Chapter ten provides an overall conclusion to the work presented in the thesis, whilst highlighting the contributions of this work to the reported literature.
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Le, Roy Jennifer. "The Pursuit of High Blocking Temperature Single Molecule Magnets using 4f/5f Cyclooctatetraenyl Complexes." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32445.
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This dissertation describes the single-molecule magnet (SMM) behaviour of f-block cyclooctatetraenyl sandwich complexes. Chapter one introduces the concepts that dictate SMM behavior particularly in f-elements. The emphasis is to understand the origin of magnetic behaviour and the properties that make lanthanide elements particularly interesting to explore. Current strategies used to predict such behaviour are discussed and a literature review on the subject is provided.
Chapter Two describes the magnetic properties of eight isostructural lanthanide sandwich complexes utilizing 1,4-bis(trimethylsilyl)cyclooctatetraenyl dianion as the ligand, [Li(DME)3][LnIII(COT”)2] (Ln = Ce, Nd, Gd, Tb, Dy, Ho, Er, Tb, COT” = 1,4-bis(trimethylsilyl)cyclooctatetraenyl dianion, DME = dimethoxyethane). The complexes display a wide range of magnetic behaviour. The best performing SMM was the erbium complex, which had a blocking temperature of 8 K. Investigating different lanthanide ions with the same ligand enabled us to evaluate our findings in relation to current models used to predict SMM behaviour in lanthanide complexes.
Chapter three extends the discussion of lanthanide sandwich complexes to include higher symmetry cyclooctatetraenyl complexes of ErIII and DyIII, [K(18-C-6)][LnIII(COT)2] (18-C-6 = 1,4,7,10,13,16-hexaoxacyclooctadecane, COT = cyclooctatetraene).The change in symmetry evoked by removing the trimethylsyl- (TMS) groups on the ligand greatly influenced the magnetic properties of both complexes. Ab initio calculations revealed that the magnetic relaxation in the ErIII complex occurs via the second excited state which contributes to the very high blocking temperature of 10 K in this complex.
Chapter four presents an organometallic building block approach to create triple decker lanthanide COT” complexes of GdIII, DyIII and ErIII with a molecular formula of LnIII2(COT”)3. Synthetically, we couple together the sandwich complexes discussed in Chapter 2 by oxidatively removing one ligand to produce linear complexes where the two metals are bridged by an aromatic COT” ligand. The magnetic properties of all complexes are compared to their respective mononuclear analogs. Most interesting is the unprecedented 4 K increase in blocking temperature of the triple decker ErIII analog compared to the ErIII mononuclear sandwich complex discussed in Chapter 2. This increase is due to a ferromagnetic dipole-dipole interaction between the ErIII ions through the COT” ring. The aromatic bridging ligand provides a GdIII - GdIII interaction of J = -0.448(1) cm-1.
Chapter five extends the discussion of magnetic exchange coupling to include linear K2(THF)4[LnIII2(COT)4] (Ln = Gd, Dy, Er, COT = cyclooctatetraenyl dianion, THF = tetrahydrofuran) complexes of GdIII, DyIII and ErIII. Each complex is composed of two LnCOT2 units bridged linearly by a potassium ion. The magnetic interaction between metal ions is much weaker than in the triple decker complexes discussed in Chapter 4, with a GdIII-GdIII interaction of J = − 0.007(4) cm–1. The magnetic properties of the quadruple decker complexes were compared to their mononuclear equivalents (Chapter 3). Surprisingly, the ErIII complex showed an increase in magnetic blocking temperature over its mononuclear analog despite the large ErIII-ErIII separation of 8.819 Å. Ab initio calculations revealed that this increase is due to single ion effects, most likely an increase in symmetry.
Chapter six deviates from lanthanide magnetism to study the magnetic properties of uranium sandwich complexes with multiple ligand systems and oxidation states. Prior to this study the SMM behaviour of uranium sandwich complexes was unknown. We report the synthesis, structure and magnetic properties of both uranium-COT” sandwich complexes and uranium-cycloheptatrienyl complexes with oxidation states spanning (III)-(V). None of the complexes showed zero-field SMM behaviour, indicating a sandwichtype ligand is not appropriate for harnessing the SMM character in uranium. We compared the slow magnetic relaxation of isostructural and valence isoelectronic uranium and neodymium complexes. The improved energy barrier in the uranium complex further motivates the use of uranium in SMM design due to its large spin-orbit coupling.
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Chiboub, Fellah Fatima Zohra. "Synthèse et détermination structurale de complexes de métaux de transition et d'entités 3d-4f." Toulouse 3, 2008. http://thesesups.ups-tlse.fr/288/.
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Ce travail concerne la synthèse, la détermination structurale par diffraction des rayons X et l'étude des propriétés magnétiques de complexes polynucléaires de cuivre, de complexes cuivre alcalino-terreux et de complexes 3d/4f. Dans le premier chapitre, est exposée la synthèse de " demi-unités " complexe et de " demi-unités " ligand, ainsi que les différentes stratégies utilisées pour l'obtention des complexes de base de Schiff non symétriques de cuivre et de nickel. La synthèse et l'étude des propriétés structurales et magnétiques de deux familles de composés polynucléaires de cuivre provenant de l'association de demi-unités complexes constitue la deuxième partie de ce travail. L'influence de la nature du groupement en ortho du donneur O(phénoxo) et du type de diamine sur la nucléarité de ces complexes a été éclaircie. Dans la troisième partie, nous décrivons comment les bases de Schiff à compartiments possédant un site de coordination N2O2 et un site de coordination O4 de plus grande taille, résultant de la réaction du métallo-ligand avec les sels d'alcalino-terreux, ont permis d'isoler une série de complexes 3d/alcalino-terreux/salicylaldimine avec des rapports 3d/alcalino-terreux différents. Dans la dernière partie, nous décrivons la préparation de complexes 3d/4f di, tri et tétranucléaires. Les ligands assembleurs sont des bases de Schiff non symétriques apportant des ponts différents. L'étude de leurs propriétés magnétiques concourt à une meilleure connaissance des facteurs responsables de la nature et de l'intensité de l'interaction magnétique. Un comportement de type SMM est vraisemblable pour le complexe tétranucléaire Cu-Tb-Tb-Cu, indiquant que la présence d'une interaction Tb-Tb n'exclut pas l'obtention de SMMThis work is concerned with the synthesis, structural determination by single crystal X-ray diffraction and study of the magnetic properties of polynuclear copper complexes, alkaline-earth/copper complexes and 3d/4f complexes. In the first chapter, the synthesis of half-unit complexes and half-unit ligands is described as well as the various strategies used for obtaining non-symmetrical Schiff base copper and nickel complexes. The synthesis and study of the structural and magnetic properties of two series of polynuclear copper compounds resulting from the association of half-unit complexes is the topic of the second part of this work. The effect of the chemical nature of the ortho-substituent to the O(phenoxo) donor and the effect of the type of diamine on the nuclearity of these complexes has been elucidated. In the third part, we describe how the compartmental Schiff bases having an inner N2O2 coordination site and a larger O4 coordination site resulting from the reaction of the metallo-ligand with the alkaline-earth salts allowed isolating a series of 3d/alkaline-earth/salicylaldimine complexes with different 3d/alkaline-earth ratios. In the last part, we describe the preparation of di-, tri- and tetra-nuclear 3d/4f complexes. The assembling ligands are non-symmetrical Schiff bases bringing different bridges. The study of their magnetic properties contributes to a better understanding of the factors responsible for the nature and intensity of magnetic interactions. An SMM type of behaviour is likely for the tetranuclear Cu-Tb-Tb-Cu complex, suggesting that the presence of a Tb-Tb interaction does not exclude an SMM behaviour
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Habib, Fatemah. "Investigating and Enhancing Spin Reversal Barriers in Dinuclear 4f Single-Molecule Magnets and the Ultimate Shift to Mononuclear 3d Complexes." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32174.
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In order for molecular magnetic materials to become applicable, they must retain their magnetisation at reasonable temperatures, which can be achieved with high energy barriers for spin reversal and high blocking temperatures. In the field of Single-Molecule Magnets (SMMs), over the last decade, the main focus has shifted from large spin complexes to highly anisotropic systems which have displayed record energy barriers. There are two main methods of increasing magnetic anisotropy in a complex: i) Choosing a metal ion that boasts high magnetic anisotropy then coupling two such ions through magnetic interactions to induce large global anisotropy, and ii) maintain a low spin or use a mononuclear complex while minimising quantum tunnelling of the magnetisation by controlling the geometric features of the metal ion. Both strategies are equally valid and have been explored in this thesis using dinuclear lanthanide as well as mononuclear 3d complexes.
In the pursuit of high-barrier SMMs via alignment of anisotropy axes, two dinuclear, quadruple-stranded helicates and one mesocate were isolated and are described in detail herein, both structurally and magnetically. Furthermore, theoretical calculations have been performed to determine the energies of Kramers doublets on each DyIII centre to derive magneto-structural correlations. To induce magnetic interactions between DyIII ions, a centrosymmetric dinuclear SMM was synthesised. Investigation of the crucial DyIII…DyIII interaction as well as its effect on the quantum tunnelling of the magnetisation has been carried out using ab initio calculations and magnetic dilution studies. Using the same system, a method of greatly enhancing the energy barriers in SMMs has been developed. It involves modifying the coordinating ligands to include electron withdrawing groups in order to yield more anisotropic metal ions. The energy barrier for spin reversal has been increased 7-fold in one case. While lanthanide chemistry has proven to be quite versatile and promising, a new branch of nanomagnets is currently being pursued: mononuclear 3d complexes as SMMs. The advantages of 3d metals include high anisotropy per ion, low spin (as anisotropy decreases with increasing spin), well-understood electronic structures and clear correlations between geometry and magnetic anisotropy. The structural and magnetic properties of three complexes based on CoII and terpyridine ligands as well as a seven-coordinate CoII complex with positive anisotropy are discussed at length. The unique slow relaxation dynamics and spin crossover behaviour has been followed using DFT and ab initio calculations, as well as EPR and magnetic dilution studies.
Overall, this thesis describes the efforts taken to synthesise high-barrier nanomagnets through understanding the origins and mechanisms of slow magnetic relaxation in both lanthanide and 3d metal complexes.
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Mattoussi, Nabila. "Assemblages supramoléculaires par complexation moléculaire ou métallique de calix[4]arène fonctionnalisés par des groupes sulfonate et carboxylate : synthèse, cristallisation et détermination des structures cristallines." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10325.
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Le travail présenté concerne la synthèse de calixarènes fonctionnalisés par des groupes sulfonates et carboxylates et l'étude détaillée des structures cristallines de leurs complexes moléculaires ou métalliques avec des métaux 3d et 4f. L'une des préoccupations majeures de ce travail concerne la compréhension des assemblages supramoléculaires dans ces systèmes. Le premier chapitre présente des éléments bibliographiques sur les calixarènes, leur histoire, les différentes conformations et les méthodes principales de fonctionnalisation puis la chimie supramoléculaire associée comprenant les complexes moléculaires et métalliques. Le deuxième chapitre est dédié à une série de complexes moléculaires de type hôte-invité formés entre le para-sulfonatocalix[4]arène (SC4) et différentes bipyridine En continuité avec ce travail nous présentons en suite la structure et les propriétés magnétiques d'un complexe métallique constitué d'un SC4 pontant deux entités dinucléaires de phenanthroline [FeIII2(μ-O)(H2O)5(phen)2] par la coordination des groupes sulfonates. Le troisième chapitre est consacré à la chimie de coordination des calixarènes sulfonatés avec les lanthanides. Nous avons mis en évidence trois types de structures cristallines qui sont toutes des polymères de coordination où les ions lanthanides jouent le rôle d'assembleur des calixarènes par la coordination des groupes sulfonates selon trois types de structure (A, B et C). Nous avons obtenu ces trois structures (A, B et C) pour l'ensemble de lanthanide (La, Pr, Nd , Eu, Gd, Tb, Dy, Ho, Yb). Le quatrième chapitre concerne la chimie de coordination des métaux de transition 3d (Co, Mn, Zn, Cu) avec des calixarènes fonctionnalisés par des groupes carboxylates sur leur partie basse. Avec le calixarène dicarboxylate nous avons obtenu une série de complexes isomorphes dans lesquels deux calixarènes sont coordinés à deux centres métalliques pour former des chaînes infinies. Le cinquième chapitre présente les résultats d'un travail exploratoire visant à synthétiser des azacalix[4]arènes, dans le but de complexer des métaux de transition. L'étude RPE des précurseurs a mis en évidence des espèces radicalairesThis work presents the synthesis of calixarenes functionalized with sulfonate and carboxylate groups and the detailed study of the crystal structures of their molecular or metal complexes with 3d and 4f metals ions. One of the major concerns of this work is the understanding of supramolecular assemblies in these systems. The first chapter gives bibliographic elements on the history, the different conformations and the main methods of functionalization of calixarenes and on their supramolecular chemistry comprising molecular and metal complexes. The second chapter is dedicated to a series of molecular complexes of the host-guest type formed between the para-sulfonatocalix[4]arene (SC4) and various bipyridine. In continuation with this work we then present the synthesis, structure and magnetic properties of a metal complex comprising a SC4 bridging by the sulfonate groups two iron(II) dinuclear entities with coordinated phenathroline [FeIII2 (μ-O)(H2O) 5(phen) 2]. The third chapter is devoted to the coordination chemistry of sulfonated calixarenes with lanthanides. We have found three types of crystal structures which are polymers wherein the lanthanide ion function as an assembler of calixarenes by the coordination of the sulfonate groups along three type of structure (A, B and C). We obtained these three structures (A, B and C) for all lanthanide (La, Pr, Nd, Eu, Gd, Tb, Dy, Ho, Yb). The fourth chapter concerns the coordination chemistry of 3d transition metals (Co, Mn, Zn) with calixarenes functionalized with carboxylate groups on lower rim. With calixarene dicarboxylate we got a series of isomorphic complexes in which two calixarenes are coordinated to two metal centers to form infinite chains. The fifth chapter presents the results of an exploratory work to synthesize azacalix[4]arene with the aim to complex transition metals ions. The EPR study of the precursors has evidenced free radical species
Book chapters on the topic "4f complexes"
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Boos, E., and T. Ohl. "Towards a Complete Calculation of γγ → 4f." In International Europhysics Conference on High Energy Physics, 1161–62. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/978-3-642-59982-8_222.
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Pointillart, Fabrice, Stéphane Golhen, and Olivier Cador. "Electroactive 4f Lanthanides Complexes Involving Tetrathiafulvalene Derivatives as Ligands." In Multifunctional Molecular Materials, 185–218. Pan Stanford Publishing, 2013. http://dx.doi.org/10.1201/b14593-7.
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Pedersen, K. S., and J. Bendix. "Molecular Fluoride-Bridged 3d-4f Complexes and Their Magnetic Properties." In Photonic and Electronic Properties of Fluoride Materials, 213–30. Elsevier, 2016. http://dx.doi.org/10.1016/b978-0-12-801639-8.00011-8.
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Guenther, B. D. "Imaging." In Modern Optics Simplified, 382–434. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198842859.003.0011.
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Treating an imaging system as a linear system and use llinear system properties to d iscuss both coherent and incoherent imaging. Use a one dimensional pin hole camera to study the theory of incoherent imaging. Two different criteria, Rayleigh and Sparrow, are used to define the resolution limits of the camera. From the simple theory define the optical transfer function and the modulation transfer function as appropriate characterizations of complex imaging systems. A review of the human imaging system emphasizes tits idfferences with man made cameras. Coherent imaging is based on Abbe’s theory of microscopy. A simple 4f imaging system can be used to understand how spatial resolution is limited by the optical aperture and by controlling the aperture, we can enhance the edges of an image or remove noise intensity noise on a plane wave. Apodizing the aperture allows astronomers to locate planents orbiting distant stars.
Conference papers on the topic "4f complexes"
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Bharwal, Anil Kumar, Yatzil Avalos, Carmen Ruiz-herrero, Olivier Margeat, Christine Videlot-Ackermann, Jorg Ackermann, Ludovic Escoubas, David Duché, and Jean-Jacques J.J. Simon. "Determination of complex optical constants of PBDB-T-2F/ITIC-4F organic solar cells." In International Conference on Hybrid and Organic Photovoltaics. València: Fundació Scito, 2022. http://dx.doi.org/10.29363/nanoge.hopv.2022.133.
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Trofimova, E. S., V. A. Pustovarov, and Q. Shi. "Fast 5d-4f luminescence in Sr9RE(PO4)7 (RE = Sc, Lu) complex phosphates doped with Pr3+ ions." In PHYSICS, TECHNOLOGIES AND INNOVATION (PTI-2019): Proceedings of the VI International Young Researchers’ Conference. AIP Publishing, 2019. http://dx.doi.org/10.1063/1.5134329.
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Zhao, S. N., H. Chang, J. Wei, and Z. Wei. "Pseudo-Color Coded Optical System Based on the Spatial Light Modulator and Charge-Coupled Device." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-86642.
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A new pseudo-color coded optical system based on the liquid crystal spatial light modulator (LC-SLM) and a digital camera (CCD) is proposed. The SLM is used to replace the holographic grating with gray-scale image information, a gray-scale image in real-time modulation methods is proposed by synthesizing phase hologram and Ronchi grating, combined with the 4f coherent optical processing system and spatial filtering. For the high resolution gray image processed with existing digital pseudo-color method, the color sensitivity is low, algorithm is very complex. For traditional optical pseudo-color method, the gray scale image needs chemical pretreatment. The process is complex and time-consuming, and the real-time modulation could not be achieved. Our new method has enhanced the flexibility and adaptability of the optical pseudo-color, and give full play to the high sensitivity, high-capacity, rich colors and other features of the optical processing mode. At the same time, it overcomes the disadvantages of pure optical system which could not perform real-time processing. Therefore, it can be widely used in the field of remote sensing, biomedical, environmental monitoring, public security and criminal investigation, etc.