The Role of Functionalisation, Asymmetry and Shape of a New Macrocyclic Compartmental Ligand in the Formation of Mononuclear, Homo- and Heterodinuclear Lanthanide(III) Complexes
✍ Scribed by Sergio Tamburini; Sergio Sitran; Valentina Peruzzo; Pietro Alessandro Vigato
- Publisher
- John Wiley and Sons
- Year
- 2009
- Tongue
- English
- Weight
- 561 KB
- Volume
- 2009
- Category
- Article
- ISSN
- 1434-1948
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✦ Synopsis
Abstract
The compartmental [1+1] macrocycle H~3~L, obtained by self‐condensation of the formyl precursor 3,3′‐(3,6‐dioxaoctane‐1,8‐diyldioxy)bis(2‐hydroxybenzaldehyde) with the amine precursor N,N‐bis(2‐aminoethyl)‐2‐hydroxybenzylamine, contains one inner ON~3~O~2~ Schiff base and one outer O~2~O~4~ crown‐like chamber. According to the experimental conditions it forms, by a template process, the stable mononuclear complexes Ln(H~3~L)(Cl)~2~(CH~3~COO)·__n__S·__m__HCl or [Ln(L)]·__n__S (Ln = La, Lu, Y, Yb, Er, Dy, Tb, Gd, Eu, Ce) with the lanthanide(III) ion encapsulated in the crown‐ether‐like and in the Schiff base site. The mononuclear complexes Ln(H~3~L)(Cl)~2~(CH~3~COO)·__n__S·__m__HCl, by further complexation with a different lanthanide(III) ion, give rise to the related heterodinuclear complexes [LnLn′(L)(Cl)~2~(CH~3~COO)]·__n__S while the homodinuclear and the heterodinuclear complexes Ln~2~(L)~3~·__n__H~2~O and LnLn′(L)~3~·__n__S could be prepared by a template reaction using the appropriate molar ratio of reactants. Their properties have been studied by using SEM‐EDS microscopy, IR and NMR spectroscopy and their compositions confirmed by thermal and ESI‐Mass spectrometric analyses. In the heterodinuclear complexes, the site occupancy of the different lanthanide(III) ions was determined by ^1^H and ^13^C NMR spectroscopy in CD~3~OD or (CD~3~)~2~SO – it was found that heterodinuclear complexation occurs in methanol with the smaller lanthanide(III) ion mainly coordinating to the Schiff base site and the larger lanthanide(III) ion to the crown site whereas, in dimethyl sulfoxide, demetalation of the weaker coordinated lanthanide(III) ion into the crown ether chamber occurs with the subsequent formation of mononuclear species in solution. The thermal decomposition of the heterodinuclear complexes forms the related mixed oxides, the stoichiometries and properties of which were determined by SEM‐EDS microscopy and X‐ray powder diffraction studies (XRD). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)