Interactions of trivalent lanthanide cations with tetradentate Schiff bases: New lanthanide(III) complexes from (1S,2S,N1E,N2E)–N,N′-bis(pyridin-2-ylmethylene)cyclohexane-1,2-diamine

A new benzodiazepine molecule and its interactions with diorganotin(IV)chlorides

“…A number of different synthetic methods have been established to prepare a plethora of Schiff base ligands, involving condensation reactions between ketones or aldehydes and amines. In previous work from our laboratory N,N,N,N tetradentate Schiff base ligands, derived from the reactions of 1,2-diaminobenzene [10,11] or ethylenediamine [12,13] with 2-acetylpyridine or 2-pyridinecarboxyaldehyde under mild conditions, as well as their transition metal or lanthanide [14][15][16][17] complexes, were synthesized and characterized. However, the reaction of 1,2-diaminobenzene with 2-acetylpyridine, under prolonged heating, led to an unexpected cyclocondensation, forming the compound 2-(2 0 -pyridyl)quinoxaline [18].…”

Interactions of Trivalent Lanthanide Cations with a New Hexadentate Di‐Schiff Base: New Lanthanide(III) Complexes from (NE,N′E)‐2,2′‐(ethane‐1,2‐diylbis(oxy))bis(N‐(pyridin‐2‐ylmethylene)ethanamine)

“…It was found that the ethylenediamine “hinge” of the di- Schiff base ligand eliminates the possibility of coplanar coordination of the four nitrogen donors [19] while when we changed the ethytlene diamine moiety with 1,2-phenylenediamine to force planar coordination of the tetradentate di-Schiff base, we ended up with the lanthanide cations outside of the four nitrogens plane [20]. In a different work, [21], we found that N,N′-bis(pyridin-2-ylmethylene)cyclohexane-1,2-diamine has an intermediate coordinating behaviour to the lanthanides. …”

Structures and fluorescence of two new hetero-dinuclear lanthanide(III) complexes derived from a Schiff-base ligand

“…Schiff-base ligands with N, O donor sets have often been used since the Schiff-base ligands may assemble coordination architectures directed by the lanthanide(III) ions [1,8], while the lanthanide ions can promote Schiff-base condensation and can give access to complexes of otherwise inaccessible ligands [9]. Owing to the stabilization of Schiff bases by coordination with lanthanide ions, it is possible to study applications of the complexes.…”