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Molecular sensors and switches have made important contributions to biomedical devices and molecular computational operations. There are numerous molecular designs using a fluorophore linked through a spacer group to a receptor(s), with a wide dynamic range, directional precision, target specificity, and molecular logic capability. Tb(III) and Eu(III) metal ions have natural luminescence lifetimes in the order of milliseconds. As a result they have been used as probes that allow discrimination between probe emission and background fluorescence using time- resolved techniques. Unfortunately the free ions themselves absorb light poorly so cannot provide the sensitivity often required of a probe or a sensor. Their performance however can be improved dra.matically by the coordination of the metal ions to organic chelate ligands containing appropriate organic fluorophores. This project is based on the design and synthesis of Tb(lU) and Eu(III) complexes of phthalimide and phthalamate derivatives as responsive lanthanide complexes. Phthalimide and phthalamate compounds are organic chromophores. Four acyclic phthalimide derivatives, Ll, L3, LS and V, were prepared through condensation reaction of phthalic anhydride and the corresponding amine derivatives in glacial acetic acid. These phthalimide derivatives, Ll, L3, LS and V, were then hydrolysed under basic conditions to yield the desired phthalamate compounds, L2, L4, L6 and L8. The yields of these phthalamate derivatives (L2, L 4, L6 and L8) were 50%-70%. They are fully characterised by lH and 13C NMR spectroscopy, elemental analysis, mass spectrometer, IR and melting point analysis. A series of macrocycles with N-substituted phthalimide pendant arm(s) L9-12were synthesised. The macrocyclic phthalimide derivatives were prepared by incorporating N-bromoalkyl phthalimide onto tri-tert-butyl-1,4,7,10- tetraazacyclododecane-1,4,7 -triacetate, di-tert-butyl-1,4,7,10- tetraazacyclododecane-1,4-diacetate and mono-tert-butyl-1,4,7,10- tetraazacyclododecane-monoacetate through nucleophilic substitution reactions. Removal of t-butyl functions and retention of phthalimide was achieved in trifluoroacetic acid to yield the final products (6%-14%). 1,4,7,10- Tetraazacyclododecane was alkylated on its 4 nitrogen sites by phthalimide function with a propyl bridge to yield L13 (10%). L9-13 were fully characterized by lH and 13C NMR spectroscopy, elemental analysis, mass spectrometer, IR and melting point analysis. Apart from Ll, L3, L4, LS and LlO all the phthalimide and phthalamate derivatives synthesised in this thesis are new. The optimal metal-to-ligand ratio of 1:2 was established for acyclic phthalamate- based terbium complexes, whereby the best antennae effects on the luminescence properties of these complexes were observed. The highest luminescence level of [Tb(L2)2J-, [Tb(L4)2J-, [Tb(L6)2P- and [Tb(LB)2]- was observed at pH ea. 6, but it was quenched at pH> 7. These four terbium complexes exhibited long emission lifetimes of the order of sub-milliseconds. Luminescence features of [TbL9], [TbLlO], [J'bLll]+ and [TbLl2)2+ showed rather weak luminescence under acidic conditions. The luminescence was enhanced under basic conditions while phthalimide functions were hydrolysed to phthalamates. Their phthalamate-based macrocyclic terbium complexes ([TbL9H]-, [TbLlOH]-, [TbLllHJ-, [TbLl2H]-, and [TbL13H]-) exhibited high quantum yields (cp) and long lifetimes (T) of the order of milliseconds at pH ea. 6. The values of <P and T were 46% and 2.4 ms respectively for [TbL9H]-, which was one of the top three terbium complexes benefiting from the macrocyclic architecture. Eu3+ complexes gave luminescence, but a rather weak antennae effect was observed. The results showing different number of chromophores appended on the macrocycle and the size of linkers have a significant effect on Φ The high efficiency of energy transfer could be quenched in the presence of particular metal ions (such as Cu2+, Fe2+, C02+, Ni2+ and Fe3+) for these terbium complexes, [Tb(L2)2J-, [TbL9H]- and [TbLl3H]-. [Tb(L2)2]- and [TbL13H]- were responsive to Cu2+ and Fe3+, while [TbL9H]- was responsive to Cu2+ and C02+. Quenching rate constants (kq) of these complexes in the presence of quenchers showed that Cu2+ has the most significant quenching effect on the luminescence of [Tb(L2)2]-. An NOR mode molecular logic gate system is devised on the basis of using these three terbium complexes, [Tb(V)2]-, [TbL9H]- and [TbL13HJ-, in the presence of responsive metal ions. In [Tb(V)2]- and [TbL13H]-, their luminescence was switched

The (trivalent) lanthanides exhibit a common sequence of phases upon the application of pressure: hcp → dhcp → fcc → “distorted-fcc”. The “distorted-fcc”’ phase (d-fcc), observed in the light lanthanides is known to be related by geometric distortions to the fcc unit cell, yet the d-fcc phase has been reported to comprise of one or two structures, with no prevailing consensus as to the solution(s). This thesis contains a detailed study of the d-fcc phase of the light lanthanides Pr and Nd. High-pressure angle-dispersive powder-diffraction techniques were employed to systematically study the phases adopted by Pr (up to 25GPa) and Nd (up to 44GPa). Particular attention was paid to solving the d-fcc of each of these elements, the structure of which is very unclear in published work. In Pr, the d-fcc between 7 and 20GPa is shown to comprise of two phases, the solutions of which are shown to be hR24 (R¯3m) and oC16 (Ibam) for the regions 7-14GPa and 14-20GPa, respectively. The pressure dependence of each of these structures over their stability range is presented. Revisions to previously-published volume vs. pressure data are made, with a different value for the volume collapse at the 4f electron delocalisation transition reported. Similarly, the d-fcc phase of Nd, stable over the pressure range 16-40GPa, is studied in detail. Nd differs from Pr by undergoing a further transition, to a hP3 (P63) structure, on pressurisation above 40GPa, before transforming to a α-Uranium phase. The distorted-fcc phase is shown, like that of Pr, to comprise of two phases, hR24 (R¯3m) and oC16 (Ibam) for the pressure regions 16-26GPa and 26-40GPa, respectively. Data on Nd are presented up to the maximum pressure achieved, 44GPa. Data from a preliminary study of La are also presented, along with a brief report on attempts to prepare a single crystal of Pr within a diamond anvil cell, by laser annealing of a powder of Pr.

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Longtemps la chimie des lanthanides divalents a été limitée par le nombre et la qualité des précurseurs disponibles. Ce travail s'intéresse donc à la préparation de nouveaux précurseurs et à leur application en activation de petites molécules dans l'optique de préparer de nouveaux matériaux.Des précurseurs peu encombrés de type triflates ont ainsi été préparés et leur comportement en solution a été étudié. L'anion triflate présentant l'avantage de favoriser les assemblages en raison de ses différents modes de coordination.Un autre type de précurseur a été synthétisé et étudié : il s'agit des lanthanidocènes. Alors que la chimie organométallique des lanthanides se heurte souvent à un contrôle difficile des symétries, un ligand à neuf chaînons a permis d'isoler les premiers ytterbocènes et samarocènes divalents.La synthèse de ces nouveaux précurseurs pose la question de leurs propriétés électroniques. Ces-dernières ont donc été étudiées sur plusieurs précurseurs de thulium divalents illustrant ainsi l'influence de la symétrie des complexes. Un choix judicieux de chimie de coordination a notamment permis d'isoler les premières molécules-aimants de lanthanides divalents.Enfin, dans un troisième temps, la réactivité vis-à-vis de petites molécules des précurseurs préparés a été étudiée montrant ainsi qu'il était possible de construire des assemblages variés par réactivité des lanthanides divalents. L'accessibilité d'un assemblage Sm/S présentant des molécules coordinées échangeables a permis de progressivement passer de la molécule au matériau par de la chimie supramoléculaire. / Divalent lanthanide chemistry has long been hampered by the lack of adapted precursors. This work is therefore focussing on the preparation of new divalent lanthanides precursors and their use in small molecule activation for building new materials.Triflate precursors were prepared and their solution properties were studied. ith their multiple coordination modes, triflate anions were shown to favour assemblies growth.Another type of precursor was also prepared: the lanthanidocene. Although organometallic chemistry of lanthanide is often known for the poor control of the complexes symmetry, a 9-membered ligand allowed the preparation of the "true" divalent ytterbocene and samarocene.The electronic properties of divalent lanthanides complexes are poorly known. The prepared thulium (II) precursors were therefore extensively studied. The influence of the symmetry on electronic properties was caracterised and a well-chosen set of ligands was proven to enable interesting magnetic properties such as single-molecule-magnet behaviour.The last part of this work focused on the reactivity of these precursors towards small molecules. Assemblies were grown from the reactivity of divalent samarium with carbon dioxide or yellow sulfur. On one of the obtained assemblies, supramolecular chemistry was carried out, progressively bridging the gap between molecules and materials.

Les systèmes moléculaires à base de cations lanthanides luminescents possèdent des propriétés photophysiques très intéressantes pour les applications en bioimagerie optique (résistance au photoblanchiment, bandes d’émission fines, temps de vie de luminescence longs). La lumière émise peut couvrir une large gamme spectrale, selon le cation lanthanide choisi. Cependant, les lanthanides ont des coefficients d’extinction faibles. Il est donc nécessaire d’utiliser une voie de sensibilisation indirecte - l’effet d’antenne, avec un chromophore placé à proximité du lanthanide. De plus, afin d’amplifier le signal émis, plusieurs cations métalliques peuvent être introduits dans la molécule. Dans cette thèse, nous avons cherché à développer de nouveaux agents potentiels d’imagerie à base de systèmes polynucléaires de lanthanides. Notre objectif a été de programmer l’assemblage de complexes supramoléculaires tridimensionnels et d’améliorer les propriétés optiques pour les applications biologiques. Pour ce faire, nous avons choisi d’employer des ligands tripodaux composés d’une ancre centrale triaminotriptycène et de trois bras possédant les sites coordinants. Ces ligands ont ensuite été modifiés de façon à optimiser les propriétés physico-chimiques. Par ailleurs, la synthèse de nouvelles plateformes centrales a été également effectuée afin de poursuivre leur développement dans le futur. La synthèse et la caractérisation de ligands tripodaux L1 et L2 et de leurs complexes avec des lanthanides ont été réalisées. Des études détaillées de spéciations avec les ligands L1 et L2 ont permis de démontrer la stabilité thermodynamique des systèmes tétranucléaires formés en préférence avec les lanthanides légers. Des études spectroscopiques ont caractérisé leur luminescence dans le visible et dans le proche infrarouge. D’autre part, nous avons préparé et caractérisé des nouveaux composés en combinant un chromophore porphyrinique et des récepteurs complexant les lanthanides. Ces sondes bimodales peuvent trouver une application dans l’imagerie et la thérapie photodynamique. / Molecular systems based on luminescent lanthanide cations have very valuable photo-physical properties for applications in optical bioimaging (resistance to photobleaching, sharp emission bands, and longue luminescence lifetimes). The emitted light can cover a wide spectral range, according to the chosen lanthanide cation. However, the lanthanides have low extinction coefficients and must be sensitized indirectly via the antenna effect by using a chromophore located in proximity. The luminescence intensity per molecule can be also increased by accommodating several lanthanides within a single compound. In this thesis, we report on the development of new potential imaging agents based on polynuclear systems with lanthanides. The main goal was to program supramolecular well-defined tridimensional complexes in order to enhance their optical properties for biological applications. To do this, we have chosen to employ tripodal ligands composed of a central triaminotriptycene anchor and three arms with coordinating sites. Moreover, these ligands have been functionalized to improve their physicochemical properties. In view of future developments, the synthesis of new central platforms was also performed. The synthesis and characterization of tripodal ligands L1 and L2 and their complexes with lanthanides were carried out. Detailed speciation studies with L1 and L2 show a high thermodynamic stability of tetranuclear systems formed preferably with lighter lanthanides. In addition, spectroscopic studies reveal that the sensitization of luminescence is achieved in the visible as well as in the near infrared. Furthermore, we have prepared and characterized novel compounds by combining a porphyrin chromophore and a receptor for lanthanide complexation. These bimodal probes may find applications in imaging and in photodynamic therapy.