A new series of lanthanide complexes with the trans-disubstituted Py2[18]aneN6 macrocyclic ligand: synthesis, structures and properties

New lanthanide complexes with the trans-disubstituted macrocyclic ligand Py-2[18]aneN(6) (denoted as L-1) were successfully synthesized. The coordination properties of compound L-1 towards different lanthanide metal ions (Ln = La-Yb, except Lu) were explored, and structural studies have been carried out both in the solid state and in aqueous solution. In all cases, complexes with a 1:1 metal:ligand molar ratio were obtained. The crystalline structures of the following compounds: [H4L1](NO3)(4), [CeL1(NO3)(2)](NO3) and [SmL1(NO3)(2)](NO3) have been characterized by single crystal X-ray diffraction. In both complexes, the asymmetric unit contains the cation complex [LnL(1)(NO3)(2)](+) (Ln = Ce3+, Sm3+) which consist of a mononuclear endomacrocyclic backbone whilst the ten coordination environment is completed by two bidentade nitrate ions. The two five membered chelate rings formed by the ethylenediamine moieties adopt (delta delta) [or (lambda lambda)] conformations and also presented a C-2 symmetry (as observed in solution by NMR). (C) 2018 Elsevier Ltd. All rights reserved.