Structure and magnetism of two chair-shaped hexanuclear dysprosium(iii) complexes exhibiting slow magnetic relaxation

Synthesis, structures and magnetic properties of four dysprosium-based complexes with a multidentate ligand with steric constraint

Four dysprosium-based complexes with a multidentate ligand with steric constraint were constructed. Their structures and magnetic properties were studied.

Coordination-Directed Self-Assembly of Functional Polynuclear Lanthanide Supramolecular Architectures

Lanthanide supramolecular chemistry is a fast growing and intriguing research field due to the unique photophysical, magnetic, and coordination properties of lanthanide ions (Ln^III). Compared with the intensively investigated mononuclear Ln-complexes, polymetallic lanthanide supramolecular assemblies offer more structural superiority and functional advantages. In recent decades, significant progress has been made in polynuclear lanthanide supramolecules, varying from structural evolution to luminescent and magnetic functional materials. This review summarizes the design principles in ligand-induced coordination-driven self-assembly of polynuclear Ln-structures and intends to offer guidance for the construction of more elegant Ln-based architectures and optimization of their functional performances. Design principles concerning the water solubility and chirality of the lanthanide-organic assemblies that are vital in extending their applications are emphasized. The strategies for improving the luminescent properties and the applications in up-conversion, host-guest chemistry, luminescent sensing, and catalysis have been summarized. Magnetic materials based on supramolecular assembled lanthanide architectures are given in an individual section and are classified based on their structural features. Challenges remaining and perspective directions in this field are also briefly discussed.

In Situ Assembled Polynuclear Zinc Oxo Clusters Using Modified Schiff Bases as Ligands

A series of different cores and nuclearity zinc metal clusters 1-5 have been synthesized using Zn(ClO4)2·6H2O, Schiff-base primary ligands, and dibenzoyl methane (DBM) or monoethanolamine (MEA) as co-ligand in a room-temperature reaction. The structure of the complexes is characterized using single-crystal X-ray diffraction. Among them, (1) [Zn(L1)(DBM)] is mononuclear; (2) [Zn4(L2)2(DBM)4], (3) [Zn4(L2)4(H2O)2(ClO4)2]·2CH2Cl2, and (4) [Zn4(L3)2(DBM)4] have a cubane core; and (5) [Zn4(L4)4(MEA)2(ClO4)2] has a ladderlike core structure. Compounds 1-5 have also been characterized using UV-vis absorption and emission spectroscopies. For an in-depth understanding of the absorption spectra of 1 and 3, density functional theory (DFT) calculations have been performed, which suggest that the transitions correspond to the π → π* intraligand charge transfer (ILCT) transitions.

Truncation reaction regulates the out-to-in growth mechanism to decrypt the formation of brucite-like dysprosium clusters

Specially shaped high-nuclear lanthanide cluster assembly has attracted widespread attention, but the study of their self-assembly mechanism is still stagnant. Herein, we used a polydentate chelating bis-acylhydrazone ligand to construct a rare 16-nuclear dysprosium cluster 1 with a brucite-like structure. The capture agents, pivalic acid and di(pyridin-2-yl)methanone, were added into the reaction system, and the hexanuclear dysprosium cluster 2 and heptanuclear dysprosium cluster 3 were obtained, respectively. Clusters 2 and 3 support the out-to-in growth mechanism as key evidence. To the best of our knowledge, this study is the first to use truncation reaction to decipher the formation mechanism of high-nuclear lanthanide clusters.

Two Dy(III) Single-Molecule Magnets with Their Performance Tuned by Schiff Base Ligands

To develop new lanthanide single-molecule magnets (SMMs), two new complexes of [Dy₂(MeOH)₂(HL¹)₂(NO₃)₂]·2MeOH (1) and [Dy₆(μ₃-OH)₂(L²)₂(HL²)₂(H₂L²)₂Cl₂(EtOH)₂]Cl₂·3EtOH·CH₃CN (2) were obtained by reacting Dy(NO)₃·6H₂O with 3-amino-1,2-propanediol in the presence of 2-hydroxynaphthaldehyde for 1 and by reacting DyCl₃·6H₂O with 1,1-di(hydroxymethyl)ethylamine in the presence of 2-hydroxynaphthaldehyde for 2, respectively, in which the Schiff base ligands of 3-(((2-hydroxynaphthaen-1-yl)methylene)amino)-propane-1,2-diol (H₃L¹) and 2-(β-naphthalideneamino)-2-(hydroxylmethyl)-1-propanol (H₃L²) were in situ formed. The two Dy(III) ions in 1 are linked by two O_alkoxy atoms of two (HL¹)^2- ligands to build a dinuclear skeleton. Complex 2 presents a nearly planar hexanuclear skeleton constructed from four edge-shared triangular Dy₃ units with the two peripheral Dy₃ units consolidated by two μ₃-O bridges and the two central Dy₃ units consolidated by one μ₃-O bridge. Obviously, they exhibit a different topological arrangement resulting from the linkage of the Schiff base ligands. Both of them are typical SMMs under zero dc fields, with a U_eff/ k_B value of 34 K for 1 and 40 K for 2, respectively. Multiple processes are involved in the relaxation processes of 1 and 2. The different SMM performances of the two titled complexes reveal a tuning effect of Schiff base ligands through tuning the coordination environments and topological arrangements of dysprosium(III) ions, which is supported by the theoretical calculations.