Lanthanide wheels

Chen XY, Bretonniere Y, Pecaut D, Imbert D, Biinzli JCG, Mazzanti M (2007) Selective self-assembly of hexameric homo- and heteropolymetallic lanthanide wheels synthesis, structure, and photophysical properties. Inorg Chem 46 625-637... 

Figs. 12 and 13 show the crystal structure of 6-Gd. Four of the linear POM-catalyst dicarboxylic acid units, 5, are linked by di-lanthanide paddle wheel junctions (Fig. 12) into the open-framework material 96). Fig. 13 shows the large channels in 6-Gd. These are filled with dimethylformamide (DMF) molecules that are hard to remove (the boiling point of DMF at 1.0 atmosphere — 151 °C). Thus while the solvent-accessible internal volume of 6-Gd is 50.5% of the crystal... 

A notable example is the wheel-shaped cationic cluster [Er36([X3-OH)3o([i3-0)6(BDC)6] " " (Figure 6.41) present in the lanthanide-transition metal sandwich framework comprising (Cus) cluster pillars and layered networks of (Erse) wheels [25, 77]. The Er + ions are linked by hydroxo and oxo bridges to give two types of smaller cluster cores cubic [Er4([i3-0)([i3-0H)3] + (Ere) and dimeric [Er2([i3-OH)2]" + (Er2) cores (Figure 6.41a). Different from the familiar cubane [Ln4([X3-OH)4] + which contains four [X3-OH groups, the present (Er4) cluster... 

Thanks to the synergistic coordination of BDC and IN, lanthanide-transition metal sandwich framework comprising CU3 cluster pillars and layered networks of Erag wheels has been reported. X-ray diffraction studies revealed a stunningly beautiful 3D network structure composed of a 2D network of wheel-shaped cationic clusters [Er36(/i3-OH)3o(/is-... 

Large billets of the rare earth metals with the exception of Eu can be cut on an oil-cooled power hack saw or water-cooled carborundum cut-off wheel. Since the reactivity of these metals increases with temperature, any method chosen should have a means of keeping the metal cool. Intermediate size billets can be cut with a hack saw, but must be kept cool to prevent contamination especially by hydrogen which is formed by reaction of the metal with H2O. The metal chips from sawing the light lanthanides, especially Ce and La, wilTreadily ignite and... 

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). 

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