Anions make the difference: conversion from zero- to one-dimensional structures and luminescent properties of lanthanide-based complexes

Abstract

Reaction of a newly designed amide type ligand, benzyl-N,N-bis[(2′-benzylaminofomyl)phenoxyl)ethyl]-amine (L) with lanthanide nitrates and picrates has produced two isostructural series of lanthanide coordination compounds, [Ln2L2(NO3)6(DMF)2]n [series 1, monoclinic P21/c, Ln = Pr (1), Sm (2), Eu (3), Tb (4), and Dy (5)] and [LnL(pic)3(CH3CH2OH)]n [series 2, triclinic P, Ln = Nd (6), Eu (7), Tb (8), and Er (9)]. Series 1 have zero-dimensional (0D) dinuclear rectangular macrocycle architectures, while series 2 exhibit one-dimensional (1D) chain patterns. Meanwhile, the two series of structures are further connected through weak intermolecular hydrogen bonds to yield three-dimensional (3D) supramolecular structures. The variations from zero- to one-dimensional coordination structures are attributed to different steric confinement of the nitrate and picrate anions. In addition, we have studied the luminescent properties of the nitrate and picrate complexes, and found that the picrate complexes give very weak luminescence due to coordinated ethanol molecules existing in complexes, which decrease the luminescence. So, herein the luminescent properties of only the Sm (2), Eu (3), Tb (4), and Dy (5) nitrate complexes are investigated in detail.