Lanthanide ions encapsulation

Carbo, J.J., Poblet, J.M. and Kortz, U. (2010) Polyoxopalladates encapsulating yttrium and lanthanide ions,... 

Encapsulation of lanthanide ions in calixarene receptors. A strongly luminescent terbium(3+) complex, J. Chem, Soc. Chem, Commun. 878-879 (1990). 

A number of non-podand (i.e., those without an apical atom or group) acyclic ligand systems have been developed for lanthanide luminescence applications. Many of these are designed as helicating ligands such that the lanthanide ion is well encapsulated despite the linearity of the ligand. 

Sabbatini, N. Guardigli, M. Mecati, A. Balzani, V. Ungaro, R. Ghidini, E. Casnati, A. Pochini, A. Encapsulation of lanthanide ions in calixarene receptors. A strongly luminescent terbium(3 +) complex. J. Chem. Soc., Chem. Commun. 1990, (12), 878-879. 

N. Sabbatini, M. Guardigli and I. Manet, Antenna effect in encapsulation complexes of lanthanide ions 69... 

The good encryption of lanthanide ions in DOTA-type molecules has also prompted the development of luminescent probes based on this structure, particularly by substituting DTMA, 1,4,7,10-tetrakis(methylcarbamoylmethyl)-1,4,7,10-tetraazacyclododecane. For instance, phenacyl and phenylphenacyl substituents have been grafted onto DTMA and the corresponding ligands, LI and L2 (Fig. 4.40) form stable 1 1 complexes in water with lanthanide ions (log/fi 12-13 at 295 K). The structure of [Tb(Ll)(H20)]3+ (Fig. 4.44) shows the ion well encapsulated into the cavity formed by the macrocyclic platform and... 

In the 1 1 complex of lanthanide nitrate with 12C4 or 15C5, the polyether does not encapsulate the lanthanide ion in its cavity due to the small cavity size, but is coordinated as tetra- or pentadentate ligand on one side as shown in Fig. 5.32. The three nitrates are bonded on the other side of lanthanide as bidentate. Thus the lanthanide is 10- and 11-coordinate in 12C4 and 15C5 complexes, respectively. In the 1 2 Sm(C104)3-15C5... 

N. Sabattini, M.Guardigliandl. Manet, 1996,23,69 (antenna effect in encapsulated complexes). G.E. Buono-core and H.LiB. Marciniak, Coord. Chem. Rev., 1990, 99,55 (quenching of excited states by lanthanide ions and chelates in solution). 

Another concern is that, for a 9-coordinate lanthanide ion in aqueous solution bound to a single tridentate DPA ligand, the six coordinated water molecules will strongly quench the luminescence (92). To eliminate the potential for solvent quenching and improve the sensitivity of the assay, we explored the use of a hexadentate ancillary ligand to encapsulate the Tb ion and exclude solvent from the coordination sphere without impeding dipicolinate chelation. 

The selectivity of the Ca2+ binding to the cavity of the cyclic peptide is quite high, especially when compared with Mg2+. The encapsulation selectivity for the Ag+-mediated dimer formation was examined by H NMR and ESI-TOF mass studies using monovalent alkali, divalent alkaline earth, or trivalent lanthanide ions, instead of Ca2+ (Figure 13.6). As a result, divalent Sr2+ and Ba2+ ions were found to form the dimeric isostructures only when excess... 

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