Lutetium initiators

Scheme 11 Yttrium and lutetium initiators supported by N,0-donor ligands...

In spite of the heavy atom, compound (32) is sufficiently fluorescent for this to be used as an analytical tool to examine localization and pharmacokinetics. In EMT-6 murine tumors, (32) localizes initially on lysosomes, with selectivity for tumor over surrounding normal tissue, and with evidence for apoptotic cell kill.137 Fluorescence studies using a hamster cheek pouch model show a maximum emission in 2-3 h, with selectivity for the tumor (x 1.5 over normal tissue) after 24 h the photosensitizer is no longer detectable.138 Lutetium texaphyrin (32) has been compared... 

Recently, rare-earth metal complexes have attracted considerable attention as initiators for the preparation of PLA via ROP of lactides, and promising results were reported in most cases [94—100]. Group 3 members (e.g. scandium, yttrium) and lanthanides such as lutetium, ytterbium, and samarium have been frequently used to develop catalysts for the ROP of lactide. The principal objectives of applying rare-earth complexes as initiators for the preparation of PLAs were to investigate (1) how the spectator ligands would affect the polymerization dynamics (i.e., reaction kinetics, polymer composition, etc.), and (2) the relative catalytic efficiency of lanthanide(II) and (III) towards ROPs. 

A mixture of 0.16g of lutetium monophthalocyaninate acetate and 0.3g of dicyanobenzo-15-crown-5 (DCBC), dried in vacuo, was rafted (melted) in a vacuum glass ampoule, immersed in Wood alloy, at successive increases of temperature from 240 to 260°C. The melted phase was kept at 260°C for 0.5 hr. The molar ratio of the initial reagents Lu salt DCBC was chosen as... 

The same group also showed that mono(cyclopentadienyl) mixed hydride/ aryloxide dimer complexes of several lanthanide elements (Y, Dy, Lu) could be synthesized easily by the acid-base reaction between the mixed hydride/alkyl complexes and an aryl alcohol [144]. These complexes reacted with C02 to generate mixed formate/carboxylate derivatives, which were moderately active initiators for the copolymerization of C02 and cyclohexene oxide, without requiring a co-catalyst. The lutetium derivative 21 was the most active (at 110°C, TOF = 9.4 h ), yet despite a good selectivity (99% carbonate linkages), the molecular weight distribution remained broad (6.15) (Table 6). 

The 5-nitro-2-anthranilates of lanthanum(III), samarium(III), terbium(III), erbium(III) and lutetium(III) were obtained as hydrates having 2.5 mol of water molecules per 1 mol of compound [167]. The compounds are isostructural. The processes of dehydration and rehydration were investigated. The first step of dehydration does not cause a change of crystal structure. The entire dehydration gives anhydrous compounds wifii different structures to the structures of hydrates. The dehydration of the La, Sm, Tb and Br compounds was reversible and rehydration gives complexes having the same crystal structures as the initial compounds. 

The presence of a multicolour electrochromic effect in rare-earth diphthalo-cyanines was first reported in 1970 by Moskalev et al. . Lutetium diphthalocyanine, LuH(Pc)2, has been studied extensively at Rockwell International Corporation by Nicholson and co-workers . This material may display different colours when polarized either anodically (red, orange) or cathodically (blue, violet) from its initial rest potential. The initially green complex film is obtained by vacuum evaporation. The anodic reaction occurs by the insertion of anions into the film and extraction of electrons rather than by loss of protons. The cathodic reaction, leading to blue and violet products, occurs by the insertion of cations. When protons are present in the electrolyte, the reaction is the following . 

The series of alumohydride complexes of dicyclopentadienylyttrium [32 - 36], -samarium [37] and -lutetium [38 - 40] has been synthesized by Bulychev and coworkers. The main routes to these products are the reactions of lithium and sodium alumohydrides or AIH3 with Cp2LnCl and similar chlorides. The structure of compounds formed in these reactions depends on the molar ratio of initial reagents, the basicity of used solvent and the existence of substituents in the cyclopentadiene ligands. In most cases the bimetallic dimer [Cp2LnAlH4(B)]2 (B = Et20, THF, Et3N) is formed. 

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