Supramolecular formation by aromatic ring stacking and hydrogen bonding in lanthanide(III) complexes with amino acids and 1,10-phenanthroline

Abstract

[Eu(ABA)(phen) 2(H 2O) 3](ClO 4) 3·3phen·4.5H 2O (1) and [Eu(Val)(phen) 2(H 2O) 3](ClO 4) 3·3phen·2H 2O (2) are two new europium complexes with amino acids and 1,10-phenanthroline (phen=1,10-phenanthroline, ABA=α-amino butyl acid, Val= l-valine). Their crystal structures were measured by X-ray crystallography. Europium atoms in both complexes are nine-coordinated with bidentate 1,10-phenanthroline and carboxylate anion of amino acids, and water molecules. In the solid state, 1 and 2 have a structure involving aromatic stacking of the coordinated and non-coordinated 1,10-phenanthroline and the oxygen atoms of non-coordinated perchlorate anions being H-bond acceptors connect [Eu(ABA)(phen) 2(H 2O) 3] 3+·3phen·4.5H 2O or [Eu(Val)(phen) 2(H 2O) 3] 3+·3phen·2H 2O in their structures. In their interactions, several C–H⋯O bonds play an important role. Owing to their different amino acid ligands and the number of lattice water molecules, there is some difference in their hydrogen bond patterns in 1 and 2. The side chain of l-valine is involved in the formation of C–H⋯O bonds. Hydrogen bond and π–π interactions determine the supramolecular formation of three-dimensional net works of both complexes.