Fluorescence lanthanide cations

The strong affinity of aliphatic phosphates for lanthanide cations was explored in the context of fluorescent warfare sensing. Complexes of fluorescent ligands... 

Fluorescence studies. The fluorescence yield and the fluorescent lifetimes of lanthanide cations in solution are functions of the nature and arrangement of the species associated with the metal in its primary coordination sphere. Based on their fluorescent properties, these elements have been classified into three categories (Crosby 1966, Whan and Crosby 1962, Sioni and Lovgren 1987)... 

There are many excellent reviews " outlining the plethora of structural and material properties of MOFs, but this chapter focuses on the incorporation of photoactive components within MOFs. The opportunities to incorporate photoactive species within frameworks are readily achievable when one considers the building-block methodology and the plethora of metal cations and ligands that can be exploited. Although it is possible to simply incorporate fluorescent metal cations, such as lanthanides or ligands, these systems have been excellently reviewed recently. Similarly, photodimerization of ligands within MOFs has also been extensively reviewed and will not be... 

GFP hopo ICBP IP3 Ln3+ mal memal MLCK nota oxine par pdta pmea py quin-2 green fluorescent protein hydroxypyridinon(at)e intestinal calcium-binding protein inositol 1,4,5-triphosphate a lanthanide(III) cation malonate methylmalonate myosin light chain kinase 1,4,7-triazacyclononane-l,4,7-triacetate 8- hydroxyquinoline pyridine-2-azo-4 -dimethylaniline propylene-1,2-diaminetetraacetate 9- [2-(phosphonomethoxy)ethyl] adenine pjrridine pjrridyl 8-amino-2- [(2-amino-5-methylphenoxy )methyl] -6-methoxyquinoline-ATJV -tetraacetate 2- [ [2-[his(carboxymethyl)amino]-5-methyl-phenoxy] methyl] -6-methoxy-8- [bis(carboxymethyl) amino] quinoline]... 

The interaction between DNA and Tb3+ in the solid state studied by fluorescence showed that one cation was present for each phosphate group [104]. Later it was shown that DNA precipitates after Ln3+ DNA ratio reaches 1 3. Lanthanides also induce conformational changes in DNA including the adaptation of Z configuration. 

Tridentate N-donor ligands are efficient in separating actinides from lanthanides selectively by solvent extraction, an area of potential great importance in treatment of used nuclear fuel rods. The tridentate ligand 2,2 6 ,2 -terpyridyl (terpy) forms a range of complexes. The perchlorate complexes [Ln(terpy)3] ( 104)3 contain nine-coordinate cations with near- )3 symmetry, a structure initially deduced from the fluorescence spectrum of the europium compound (Section 5.4) and subsequently confirmed by X-ray diffraction smdies (Figure 4.7)... 

A powerful, but less frequently used, method for studying the complexation of trace metal cations by DOM is lanthanide ion probe spectroscopy (Dobbs et al., 1989). In this method, fluorescence intensities of Eu(lll) at two emission wavelengths are used to determine the proportions of complexed and free Eu(lll). When a competing metal cation is added to the solution, its complexation by DOM causes the fluorescence... 

Very few ions are directly detectable by uv/vis absorption spectroscopy. However, if a postcolumn reaction is performed to chelate a cation with a chromophore (color producing group), to add a fluorescing agent, or to simply react the compound with another compound, such as using ninhydrin with amino acids, then uv/vis spectroscopy can be used. An example of such a system is the separation of lanthanides shown in the cation section. 

An important feature in the spectroscopic behavior is that of fluorescence or luminescence of certain lanthanide ions, notably Y and Eu, when used as activators in lanthanide oxide, silicate, or transition-metal oxide lattices. Oxide phosphors are used in color television tubes. Certain of the +2 ions trapped in CaF2 lattices, as well as organic cation salts of complex anions such as [Eu /J-diket4] , show laser activity. 

Oj to 02, which is again a measure of the ability to stabilize anionic charge. The fluorescence shifts are given in Table 3.31 and the correlation is shown in Figure 3.32. The orders Li >Na+ andMg +>Ca +>Sr > Ba + show that Lewis acidity decreases with the size of the cation. According to this scale, the tin halides are comparable in acidity to Mg +. The strong Lewis acidity of Sc +, and the lanthanides, such as La + and Yb, has been exploited in various synthetic applications. 

Because the lanthanides ("rare earths") have become prominent in the manufacture of fluorescent lamps, we will address this technology next to show how they differ from the Sq activators given above. We will find that these cations can be used in situations where no other activators can be applied. 

Reaction of terpy with lanthanide perchlorates in MeCN affords [La(terpy)3](C104)3-2MeCN 0.67H20, [Ln(terpy)3] (C104)3-MeCN.H20 (Ln = Ce, Pr, Sm, Eu), [Ln(terpy)3] (C104)3 (Eu, Lu, Y) all of these have nine-coordinate [Ln(terpy)3] + cations with near-Ds symmetry, a structure originally deduced from the fluorescence spectrum of the europium complex and subsequently confirmed by X-ray diffraction (Figure 19). 

---