Lanthanides polyaminocarboxylate

Fluorescence kinetic measurements were applied to the determination of hydration numbers in lanthanide-polyaminocarboxylate complexes the results are given in table 5 (Brittain et al. 1991, Brittain and Jasinski 1988). Measurements of hydration numbers as a function of the solution pH for Eu " and Tb " complexes showed the presence of three buffer regions the first one at low pH in which the hydration number of the cations is equivalent to that of the free ions the second one in the pH range of 4-8 in which complexation decreases the hydration numbers and the third one at high pH (ca. 9-12) being associated with the formation of ternary hydroxo complexes. 

Another point stemming out of Table 4.1 is that, ideally, the delay and acquisition times should be adapted to the decay time of the luminescent probe. This is not quite easy with chopper-fitted microscopes since the delay and acquisition times not only depend on the rotation speed of the chopper but, also, on the number of blades. Optimum working conditions would therefore require changing the chopper wheel, depending on the luminescent stain, which is not very practical. Microscopes are therefore usually fitted with chopper wheels adequate for one class of LLBs (e.g. lanthanide polyaminocarboxylates, with lifetimes around 600-700 ps). There are other ways of continuously modifying the time delay, but they also have their drawbacks (see below). 

When not complexed, lanthanide ions have a high affinity for bone in vivo because they act as calcium ion mimics. Because the lanthanides undergo hydrolysis above a pH of 4, they readily form radiocolloids when not complexed, and are then taken up by the liver. This bone and liver uptake results in non-specific radiation doses to non-target (normal) tissues and organs and is undesirable.91 The polyaminocarboxylate class of ligands are considered to be the optimal choice for the basis of BFCAs for the+3 metal cations, including the lanthanides. It is essential that the... 

Functionalized organic dyes with polyaminocarboxylate have been widely utilized as feasible sensitizers to afford visible region excitation for sensitization of NIR lanthanide luminescence [36 5]. Verhoeven and coworkers [36, 37] first prepared a series of neodymium(III), erbium(III), and ytterbium(III) complexes with polyaminocarboxylate-functionalized fluorescein (21) and eosin (22) as sensitizing chromophores. These complexes show sensitized NIR... 

Lanthanide complexes with macrocyclic ligands such as those based on 1,4,7,10-tetraazacy-clododecane or polyaminocarboxylates have been studied extensively by CPL spectroscopy. These complexes often possess large stability constants in aqueous solution and, moreover, present interesting chiroptical properties. There have been a number of reports of CPL... 

The rate of water exchange between the inner coordination sphere of rare earth ions and bulk water has been extensively studied by ultrasonic absorption and NMR spectroscopy. It is very fast and ranges between lO and 10 s (Cossy and Merbach 1988, Rizkalla and Choppin 1991). Ligand substitution processes and the kinetics of lanthanide complexation in water, especially with polyaminocarboxylates, have also been the subject of several studies (Lincoln 1986, Nash and Sullivan 1991). As for the determination of solvation numbers, investigations in anhydrous organic solvents are more sporadic. 

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