Complexes of metals as potential anion receptors

An important class of anion receptors are based on bimetallic complexes with phenols bearing an pendant arms in 2,6-positions. A ligand of this type, 2,6-bis[(N- methylpiperazine-1-yl)methyl]-4-formyl phenol (L1), was prepared using the Mannich reaction. An attempt to prepare a similar compound L2 yield only an oily product. The molecular structure of compound L1 was determinated by X-ray diffraction. Comparison of the L1 structure with similar ones from CCDC showed important influence of the intramolecular H-bond on pendant arms orientations in this type of compounds. Further synthetic exploitation of the aldehyde group (in the position 4) was tested by reaction with 4-nitroaniline. The Shiff base (L3) was obtained but only as an oily substance. Reactions of L1 with Cu(ii) and Zn(ii) perchlorate or acetate produce complexes; the compound [Cu2L1(OH)(OAc)(H2O)]ClO4 (K1) was obtained in a crystallic form. The interactions of anion-bimetallic complex receptor were discused from stereochemical point of view using the structural data from CCDC in the last part of this work