RESUMO
Several series of selectively deuterated 2,2'-bipyridine-based cryptates with the near-IR emissive lanthanoids Pr, Nd, Er, and Yb are reported. The structural and luminescence properties of these complexes have been comprehensively investigated. A combination of experimental techniques (X-ray crystallography, lanthanoid-induced NMR shift analysis, luminescence, vibrational near-IR absorption) and theoretical concepts has been applied with a focus on nonradiative deactivation through multiphonon relaxation of lanthanoid excited states by aromatic, high-energy C-(H/D) oscillators. It is shown that the characteristics for the overtones of these vibrational modes deviate substantially from harmonic oscillators and that anharmonicity within a local-mode Morse model is an essential parameter for any accurate description. The spectral overlap integrals (SOIs) of lanthanoid electronic states with aromatic C-(H/D) overtones are evaluated quantitatively for different lanthanoid/oscillator combinations and the implications for luminescence enhancement through deuteration is discussed. Simple Gaussian functions are proposed as appropriate mathematical forms for the empirical approximation of SOIs.
RESUMO
Background-free fluorine (19F) MR imaging exhibits an excellent degree of specificity, and facilitates among others the in vivo visualization of inflammatory processes. Merging19F MR images with morphologically matching1H MR images enables the exact anatomic localization of the observed19F signal. Biochemically inert nanoemulsions of perfluorocarbons, which are known to be taken up by the macrophage/monocyte system, are widely used as contrast agents for preclinical applications. Herein, the most common protocols are described to obtain high-resolution and artifact-free19F MR images even for compounds with complex19F MR spectra. In addition, we report on the utilization of perfluorocarbons with individual spectral identities and targeting approaches to specifically visualize thrombi by19F MRI.
Assuntos
Fluorocarbonos , Processamento de Imagem Assistida por Computador/métodos , Inflamação/diagnóstico , Imageamento por Ressonância Magnética/métodos , Animais , Modelos Animais de Doenças , Radioisótopos de Flúor , CamundongosRESUMO
The first enantiomerically pure 2,2'-bipyridine-based cryptand is reported. Complexation of this macrobicyclic ligand with the trivalent lanthanoid cations Yb and Lu produces enantiomerically and diastereomerically pure cryptates in solution. The Yb cryptate shows near-IR photoluminescence with lifetimes of up to τ = 29.8 µs in CD3OD.
RESUMO
The tetradentate ligand 4,4'-bis(trifluoromethyl)-2,2'-bipyridine-6,6'-dicarboxylic acid (H(2)1) and three corresponding anionic rare earth complexes [RE(1)2](-) (RE = Y, Tb, Dy) were synthesized. The terbium and dysprosium complexes show lanthanoid-centered luminescence in aqueous solution, as well as paramagnetically enhanced longitudinal magnetic relaxation of the (19)F nuclei.