Enantiopure Chiral Two-dimensional Sinusoidal Lanthanide(III) Coordination Polymers Based on R-/S-2-Methylglutarate: Luminescence, Magnetic Entropy Change, and Magnetic Relaxation

Abstract

As a base for neutralizing homochiral dicarboxylic acids [R-/S-2-methylglutaric acid, abbreviated as (R/S)-2-MG] rather than an N-donor ligand, 1,3-di(4-pyridyl)propane participates in the self-assembly of isostructural, homochiral lanthanide(III) coordination polymers derived from (R/S)-2-MG at room temperature, which show 2D sinusoidal ruffling (4, 4) network structures with the formulas {). Among them, the europium(III) and terbium(III) compounds show solid fluorescent properties characteristic of lanthanide(III) ions, while the dysprosium(III) compound may exhibit magnetic relaxation. Furthermore, the magnetic entropy change or magnetocaloric effect of the gadolinium(III) complex is studied.

Asymmetric Assembly of Chiral Lanthanide(III) Tetranuclear Cluster Complexes Using Achiral Mixed Ligands: Single-molecule Magnet Behavior and Magnetic Entropy Change

“…On the other hand, if chirality is introduced into molecular magnets, it will bring valuable physical properties such as nonlinear optics, − ferroelectricity, − and magneto-optical effects, − making them attractive multifunctional molecular materials. The general case is to obtain chiral structured molecule-based magnets by chiral ligand coordination − or even by cocrystallizing with chiral organic molecules . Another more challenging case is to use achiral ligands to spontaneously construct chiral structured molecule-based magnets, which involve helical chirality, Δ/Λ octahedral coordination configuration of transition metal ions, and cooperative orientation of anions and cations in the axial direction .…”

Two-Dimensional Metal-Organic Framework Materials: Synthesis, Structures, Properties and Applications

“…SMM and slow magnetic relaxations − are the common feature in Dy­(III) MOFs. Interestingly, a Gd­(III) MOF is reported to exhibit magnetocaloric effect, whereas Er­(III) and Gd­(III) 2D MOFs display antiferromagnetic interactions. ,, A number of heterobimetallic MOFs containing Cu­(II) and lanthanide­(III) have been investigated for magnetic properties such as SMM, , ferromagnetic behavior below 50 K, and spin glass like unusual field dependent magnetic relaxation …”

LnIII (Ln = La, Gd, and Dy) Benzimidazolium Tricarboxylate Coordination Polymers with Hydrogen Bonding Modulated Magnetic Relaxation

“…These molecular magnets are the promised candidate for various technological applications such as high-density data storage devices, spintronics, quantum computation, qubit, etc. , The anisotropic energy barrier for magnetic relaxation through the Orbach process is mainly due to axial magnetic anisotropy. , Due to the unquenched orbital angular momentum and strong spin–orbit coupling, lanthanides have inherent large magnetic anisotropy and are suitable candidates to construct SMMs. To date, several mono- and multinuclear systems/complexes, including Ln-based coordination polymers have been reported, ,− of which dysprosium metallocene complexes, with high axial anisotropy have shown a higher performance. − The under barrier magnetic relaxations such as quantum tunneling of magnetization (QTM), Raman, and direct processes suppress the high-performance of SMMs. − The more effective QTM process reported in the lanthanide systems consists of the strong admixing of the ground ± mJ state with the low lying excited ± mJ states owing to the weak crystal field effect on the Ln III ion. − However, the symmetry strategy around lanthanide geometry can help to minimize the QTM. ,,, As stated above, the insignificant separation of the excited states from the ground state can promote QTM, while the presence of QTM in high-performance SMMs, which consist of well-separated excited ± mJ levels, can be attributed to the vibronic coupling which in turn triggers the magnetic relaxation. , Not only the vibronic coupling but also the presence of other factors such as hydrogen bonding, size of the counterions, etc., are reported to trigger/promote the QTM by introducing the transverse component. ,, In this line of interest, we have isolated a series of novel 1D lanthanide (Dy ( 1 ‑Dy ), Gd ( 2 ‑Gd ), and La ( 3 ‑La )) coordination polymers by utilizing the mesityl derived benzimidazolium tricarboxylic acid H 3 L ligand system having three flexible carboxylate arms for coordination. The direct current (dc) and alternating current (ac) magnetic susceptibility data were recorded for 1 ‑Dy and 2 ‑Gd.…”