60239-18-1Relevant articles and documents
Cherenkov Radiation-Mediated In Situ Excitation of Discrete Luminescent Lanthanide Complexes
Cosby, Alexia G.,Ahn, Shin Hye,Boros, Eszter
, p. 15496 - 15499 (2018)
Lanthanide luminescence, while ideal for in vivo applications owing to sharp emission bands within the optical window, requires high-intensity, short-wavelength excitation of small organic “antenna” chromophores in the vicinity of the lanthanide complex to access excited f-orbital states through intersystem crossing. Herein, we explored Cherenkov radiation of the radioisotopes 18F and 89Zr as an in situ source of antenna excitation. The effective inter- and intramolecular excitation of the terbium(III) complexes of a macrocylic polyaminocarboxylate ligand (hydration number (q)=0, quantum yield (φ)=47 %) as well as its analogue functionalized to append an intramolecular Cherenkov excitation source (q=0.07, φ=63 %) was achieved. Using conventional small-animal fluorescence imaging equipment, we have determined a detection limit of 2.5 nmol of Tb(III) complex in presence of 10 μCi of 18F or 89Zr. Our system is the first demonstration of the optical imaging of discrete luminescent lanthanide complexes without external short-wave excitation.
Method for preparing contrast agent
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Paragraph 0005; 0058-0061, (2020/07/24)
The invention provides a method for preparing a contrast agent. Specifically, the preparation method comprises the following steps: enabling a complex liquid composition containing a macrocyclic chelate and lanthanide elements to sequentially pass through Relite CNS cationic resin and Relite 3As anionic resin to obtain a high-purity liquid solution, and then adjusting the pH value of the solution;and freeze-drying or low-temperature spray-drying to obtain a contrast agent solid, and further weighing a certain amount of the solid to prepare a contrast agent preparation for medical contrast.
Including and Declaring Structural Fluctuations in the Study of Lanthanide(III) Coordination Chemistry in Solution
Nielsen, Lea Gundorff,S?rensen, Thomas Just
, (2019/11/14)
The physicochemical properties of lanthanide(III) ions are directly linked to the structure of the surrounding ligands. Rapid ligand exchange prohibits direct structure-property relationships from being formed for simple complexes in solution because the property measured will be an average over several structures. For kinetically inert lanthanide(III) complexes, the simpler speciation may alleviate the problem, yet the archetypical complexes formed by ligands derived from cyclen are known to have at least four different forms in solution - each with a variation in the crystal field that gives rise to significantly different properties. Slow interchange between forms has been engineered, so that a single complex geometry can be studied, but fast or intermediate interchange between forms is much more commonly observed. The rapid structural fluctuation can report on the changing chemical environment and can be disregarded if a specific property of a lanthanide(III) complex is exploited in an application. However, if we are to understand the chemistry of the lanthanide(III) ions in solution, we must include the structural fluctuation that takes place even in kinetically inert lanthanide(III) complexes in our studies. Here, we have scrutinized the processes that determine the speciation of lanthanide(III) complexes of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate (DOTA)-like ligands, in particular the processes that enable exchange between forms that have different physicochemical properties, exemplified by the exchange between the diastereomeric capped square-antiprismatic (cSAP) and capped twisted-square-antiprismatic (cTSAP) forms of DOTA-like lanthanide(III) complexes. In the characterization of a kinetically inert f-element complex, understanding the structural fluctuation in the system is critical because a single observed property can arise from a weighted average, from all forms present, or from a single form with a dominating contribution. Further, the experimental condition will influence both the distribution of lanthanide(III) species in solution and the rates of the processes that change the coordination sphere of the lanthanide(III) ions. This is highlighted using data from a series of cyclen-derived ligands with different pendant arms and different denticity. The data were obtained in experiments that take place on different time scales to show that the rate of the process that results in a structural change must be considered against the time of the experiment. We conclude that the structural fluctuations must be taken into account and that they cannot be predicted from the ligand structure. Thus, an estimate of the exchange rates between forms, the relative concentrations of the specific forms, and the effect of the specific structure of each form of the complex must be included in the description of the solution properties of f-element chelates.