Molecular movements inside [1+1] asymmetric compartmental macrocycles: Formation of positional mononuclear and hetero-dinuclear lanthanide(III) isomers and related homo-dinuclear complexes

摘要

The mononuclear macrocyclic lanthanide(III) complexes, [Ln(H2L)(H2O)(4)]Cl-3 (Ln = Y, La, Ce, Cu, Tb, Yb, Lu; H2L = H2LA, H2LB' H2LC) were prepared by condensation 3,3'-(3,6-dioxaoctane-1,8-diyldioxy)bis(2-hydroxybenzaldehyde) or 3,3'-(3-oxapcntane-l,5-diyldioxy)bis(2-hydroxybenzaldehyde) with 1,5-diamino-3-azamethylpentane or 1,7-diamino-3-azamethylheptane in the presence of LnCl(3) center dot nH(2)O as templating agent. The asymmetric [1+1] ligands H2LA, H2LB and H2LC contain one smaller or larger N3O2 Schiff base site and one crown-ether like 0204 or 0203 site. The preference of the lanthanide ion to reside into the Schiff base or the crown-ether like chamber was investigated in the solid state and in methanol or dimethylsulfoxide solution. It was found that in the solid state or in methanol the lanthanide(III) ion coordinates into the O2On site while in dimethylsulfoxide demetalation and partial metal ion migration from the O2On into the N3O2 chamber occur. The mononuclear lanthanide(III) complexes [Ln(H2L)(H2O)(4)]Cl-3 with the Ln(3+) ion in the O2On site have been used as ligands in the synthesis of the heterodinuclear complexes LnLn(L)(Cl)(4)center dot 4H(2)O by reaction with the appropriate Ln'(III) chloride in methanol and in the presence of base. The related homodinuclear complexes Ln,(L)(Cl)(4) center dot 4H20 have been prepared by the one-pot condensation of the appropriate precursors in the presence of base and of the lanthanide(III) ion as templating agent.