Cinnamic acid derivative rare-earth dinuclear complexes and one-dimensional architectures: synthesis, characterization and magnetic properties

Abstract

Discrete and extended architectures based on the association of lanthanide ions with two derivatives of cinnamic acid (2-methoxycinnamic acid and 3-methoxycinnamic acid) have been synthesized and characterized by IR spectroscopy, elemental analyses, X-ray diffraction and magnetic measurements. The use of the 2-methoxycinnamic ligand enables the synthesis of a series of dinuclear complexes (Ce (1), Nd (2), Gd (3), Dy (4)), while the presence of 3-methoxycinnamic acid induces the formation of one-dimensional coordination polymers (Ce (5), Nd (6), Dy (7)). Investigations of the magnetic properties of the complexes reveal that they all exhibit field-induced slow relaxation of the magnetisation, mainly induced by Raman and direct relaxation processes.

Field-Induced Slow Relaxation in a Dinuclear Dysprosium(III) Complex Based on 3-Methoxycinnamic Acid

“…in the presence of sodium hydroxide in a DMF/water mixture allows for the formation of colorless crystals after re-crystallization in DMSO. The crystals that usually form rapidly are a one-dimensional coordination polymer, which we previously reported [30]. Remarkably, we have found that the kinetics of crystallization constitutes an important parameter that can be used to provide a further degree of control.…”

“…This therefore explains the need to use a DC field to reduce this relaxation. The comparison with the previously reported dinuclear dysprosium-based complex involving the 2-methoxycinnamic acid derivative, as well as with the 1-D coordination polymer based on the 3-methoxycinnamic acid ligand [30] clearly sheds light on the role of the coordination environment and packing arrangement over the slow relaxation of the magnetization. While two relaxation processes have been evidenced in the dinuclear complex incorporating the 2-methoxycinnamate, the Orbach process was found negligible in contrast to Raman and direct processes.…”

“…Such deviation originates from the thermal depopulation of the Stark sublevels, which may be associated with dominant antiferromagnetic interactions between the two bridged Dy 3+ ions. As previously evidenced in such carboxylate bridged systems, the strength of the magnetic interactions should be however relatively weak [15,30]. The field dependence of the magnetization measured at 1.…”

“…The asymmetric unit consists in one crystallographically independent Dy 3+ ion and three L − ligands. The molecular arrangement is reminiscent that the dinuclear complexes obtained with the 2-methoxycinnamic acid [30]. The structure of 1 can be described as two nine-coordinated Dy 3+ ions that are related via an inversion center and which are linked by six carboxylate groups from six L − anions.…”

Luminescent and magnetic bifunctional coordination complex based on a chiral tartaric acid derivative and europium

“…Apart from their excellent magnetic properties, most Ln-CPs also display characteristic sharp and narrow luminescence emissions originating from f-f transitions of the Ln 3+ ions, featuring excellent colour purity, long fluorescence lifetimes and high quantum yields (Roy et al, 2014;Xu et al, 2017;Zhang et al, 2017). Owing to the prominent optical and magnetic properties of Ln-CPs, it is of great importance and an enormous challenge to build dual optical-magneto materials based on lanthanide ions (Li et al, 2015(Li et al, , 2017a which have potential applications in luminescent sensing, magnetic resonance imaging (MRI), cryogenic magnetic refrigeration, high-density information storage and quantum computations (Khalfaoui et al, 2017;Li et al, 2015;Liu et al, 2014;Zhao et al, 2015).…”