The luminescence properties of lanthanoid ions can be dramatically enhanced by coupling them to antenna ligands that absorb light in the UV-visible and then efficiently transfer the energy to the lanthanoid centre. The synthesis and the complexation of Ln{sup III} cations (Ln = Eu, Gd) for a ligand based on four 1-hydroxy-2-pyridinone (1,2-HOPO) chelators appended to a ligand backbone derived by linking two L-lysine units (3LI-bis-LYS) is described. This octadentate Eu{sup III} complex ([Eu(3LI-bis-LYS-1,2-HOPO)]−) has been evaluated in terms of its thermodynamic stability, UV-visible absorption and luminescence properties. For this complex, the conditional stability constant (pM) is 19.9, which is an order of magnitude higher than diethylenetriaminepentacetic acid at pH = 7.4. This Eu{sup III} complex also shows an almost two-fold increase in its luminescence quantum yield in aqueous solution (pH = 7.4) when compared with other octadentate ligands. Hence, despite a slight decrease of the molar absorption coefficient, a much higher brightness is obtained for [Eu(3LI-bis-LYS-1,2-HOPO)]−. This overall improvement was achieved by saturating the coordination sphere of the Eu{sup III} cation, yielding an increased metal-centred efficiency by excluding solvent water molecules from the metal's inner sphere.

This comprehensive book presents the theoretical principles, current applications and latest research developments in the field of luminescent lanthanide complexes; a rapidly developing area of research which is attracting increasing interest amongst the scientific community. Luminescence of Lanthanide Ions in Coordination Compounds and Nanomaterials begins with an introduction to the basic theoretical and practical aspects of lanthanide ion luminescence, and the spectroscopic techniques used to evaluate the efficiency of luminescence. Subsequent chapters introduce a variety of different applications including: • Circularly polarized luminescence • Luminescence bioimaging with lanthanide complexes • Two-photon absorption of lanthanide complexes • Chemosensors • Upconversion luminescence • Excitation spectroscopy • Heterometallic complexes containing lanthanides Each chapter presents a detailed introduction to the application, followed by a description of experimental techniques specific to the area and an extensive review of recent literature. This book is a valuable introduction to the literature for scientists new to the field, as well as providing the more experienced researcher with a comprehensive resource covering the most relevant information in the field; a ‘one stop shop’ for all key references.

Transition metal paramagnetic chemical exchange saturation transfer (paraCEST) agents were developed and optimized as responsive pH-and temperature-dependent probes for magnetic resonance imaging (MRI). This dissertation is focused on the solution chemistry and solid state structures of the Co(II), Fe(II), and Ni(II) complexes of amide- appended triaza-, tetraaza-, and mixed aza-oxo macrocyclic paraCEST agents. Crystallographic data showed that nitrogen and oxygen donor atoms of the hexa-, hepta- or octa-dentate amide-append macrocyclic ligands coordinate to the metal ions and generated six-, seven- or eight- coordinate complexes. The proton NMR spectra of the complexes showed highly dispersed proton resonances that were either relatively sharp or broad depending on the metal center. Complexes were further characterized by monitoring their dissociation under biologically relevant conditions including solutions containing phosphate and carbonate or Zn(II) . Also, the dissociation of the complexes under acidic conditions (pD 2-4) was monitored over a 12 hour period. Solutions of the paraCEST agents in 20 mM HEPES (pH 7. 4) and 100 mM NaCl showed highly shifted (40-112 ppm) and intense CEST peaks (9-40%) at 37 degrees C on a 11. 7 T NMR spectrometer. Temperature-dependent CEST experiments uncovered complexes with improved sensitivity and temperature coefficient values in the range -0.56 to -0.12 ppm degrees C. Complexes were studied in rabbit serum, 4% agarose gel (w/w), or egg white to simulate possible in vivo interactions with biomacromolecules. CEST spectra with corresponding rate constants for proton exchange are reported under these conditions. CEST phantoms of the complexes on a 4. 7 T MRI scanner at 37 degrees C are compared. These in vitro CEST NMR and MRI experiments indicate that the complexes show promise for use as probes for mapping in vivo pH changes or paraCEST thermometry imaging. The third chapter of this dissertation is focused on the tetradentate PNA-HOPO and simple bidentate 1-Hydroxy-2-(1H)-pyridinone-2-carboxylic acid propylamide (Pr-1,2-HOPO) interaction with the nine coordinate Eu(III) ion. Peptide nucleic acids (PNA) that are modified to contain bidentate ligands for lanthanide ion binding are under development as target specific MRI contrast agents. The substitution of a nucleobase pair with 1,2-hydroxypyridinones (1,2-HOPO) introduced a binding site for lanthanide(III) ions in the HOPO-modified PNA duplex (PNA-HOPO). Non-modified PNA does not bind strongly to lanthanide(III) ions. Ln(III)-1,2-HOPO complexes are useful for sensitizing Ln(III) ion luminescence for biological imaging and Ln(III) based MRI. Direct excitation Ln(III) luminescence, sensitized luminescence, optical thermal melting experiments, and UV-vis titrations confirmed the coordination of the Eu(III) to PNA-HOPO. Studies of the PNA-HOPO duplex were compared to non-modified PNA duplex and Pr-1,2-HOPO to determine the binding mode.

With applications across chemistry, physics and medicine, nuclear magnetic resonance is a proven, uniquely versatile and powerful spectroscopic technique. The success of NMR and its constant redevelopment means that the literature is vast and wide-ranging. Each chapter in this volume is a distillation of the key recent literature in different areas, covering the spectrum of NMR theory and practice, and including theory and computation of nuclear shielding, NMR of soft matter, hyperpolarisation techniques and NMR of living systems. These reports are invaluable both for new researchers wishing to engage with literature for the first time, and for seasoned practitioners, particularly service managers, needing to keep in touch with the ever-expanding ways in which NMR is used.

Lanthanide elements were first used some thirty years ago in the optical glass industry, followed shortly by their use as NMR shift reagents in organic chemistry. Since then, the application of lanthanides in studies of organic and biochemical systems by use of their NMR and spectroscopic properties has created a rapidly growing interest in the physics and chemistry of these elements. Their use in industrial catalysts, electronic and optical components, high-temperature superconductors, in medicine as X-ray intensifying materials, relaxation agents for imaging techniques or radioisotopes for pharmaceutical applications, have combined with their utilisation in science as probes of a wide variety of phenomena giving them a prominent place in modern science. In this book, leading experts describe the various facets of the application of lanthanides as probes in life, chemical and earth sciences. The aim is to provide guidance to scientists who may wish to use the unique advantages of lanthanide probes in their own fields.To supplement the chapters on the basic concepts of the application of lanthanides, chapters are provided on the basic chemistry of these elements and on the synthetic and analytical aspects of lanthanides and their compounds. The book thus provides a great deal of useful information which will no doubt assist scientists in using these fascinating and valuable elements in their research.