Enantioselective self-assembly of triangular Dy3 clusters with single-molecule magnet behavior

Solid state structures and solution behaviour of tetranuclear lanthanide(III) carbonate-bridged coordination compounds of chiral 3 + 3 amine macrocycle

The linking of two dinuclear macrocyclic units of large triphenolic hexaazamine by two carbonate anions results in the formation of dimeric tetranuclear Sm(III), Eu(III) and Gd(III) complexes. These complexes were initially obtained serendipitously by fixation of atmospheric carbon dioxide and subsequently obtained in a rational way by the application of carbonate salts. The X-ray crystal structures of these isomorphic complexes show highly folded conformation of the macrocycle. This type of conformation is also confirmed by 2D NMR spectra of the Sm(III) complex. The ESI-MS and NMR spectra reveal also that these carbonate complexes exist in solution in two different forms that are in a concentration-dependent dynamic equilibrium.

Lanthanide Single-molecule Magnets: Synthetic Strategy, Structures, Properties and Recent Advances

Single-molecule magnets (SMMs) show wide potential applications in the field of ultrahigh-density storage materials, quantum computing, spintronics, and so on. Lanthanide (Ln) SMMs, as an important category of SMMs, open up a promising prospect due to their large magnetic moments and huge magnetic anisotropy. However, the construction of high performance for Ln SMMs remains an enormous challenge. Although remarkable advances are focused on the topic of Ln SMMs, the research on Ln SMMs with different nuclear numbers is still deficient. Therefore, this review summarizes the design strategies for the construction of Ln SMMs, as well as the metal skeleton types. Furthermore, we collect reported Ln SMMs with mononuclearity, dinuclearity, and multinuclearity (three or more Ln spin centers) and the SMM properties including energy barrier (U_eff ) and pre-exponential factor (τ₀ ) are described. Finally, Ln SMMs with low-nuclearity SMMs, especially for single-ion magnets (SIMs), are highlighted to understand the correlations between structures and magnetic behavior of the detail SMM properties are described. We expect the review can shed light on the future developments of high-performance Ln SMMs.

An Enzyme-Free Photoelectrochemical Sensor Platform for Ascorbic Acid Detection in Human Urine

A novel enzyme-free photoelectrochemical (PEC) potential measurement system based on Dy-OSCN was designed for ascorbic acid (AA) detection. The separation and transmission of internal carriers were accelerated and the chemical properties became more stable under light excitation due to the regular microstructure of the prepared Dy-OSCN monocrystal. More importantly, the PEC potential method (OCPT, open circuit potential-time) used in this work was conducive to the reduction of photoelectric corrosion and less interference introduced during the detection process, which effectively ensured the repeatability and stability of the electrode. Under optimal conditions, the monocrystal successfully served as a matrix for the detection of AA, and the prepared PEC sensor exhibited a wide linear range from 7.94 × 10−6 mol/L to 1.113 × 10−2 mol/L and a sensitive detection limit of 3.35 μM. Practical human urine sample analysis further revealed the accuracy and feasibility of the Dy-OSCN-based PEC platform. It is expected that such a PEC sensor would provide a new way for rapid and non-invasive AA level assessment in human body constitution monitoring and lays a foundation for the further development of practical products.

Imine- and Amine-Type Macrocycles Derived from Chiral Diamines and Aromatic Dialdehydes

The condensation of aromatic dialdehydes with chiral diamines, such as 1,2-trans-diaminocyclohexane, leads to various enantiopure or meso-type macrocyclic Schiff bases, including [2 + 2], [3 + 3], [4 + 4], [6 + 6] and [8 + 8] condensation products. Unlike most cases of macrocycle synthesis, the [3 + 3] macrocycles of this type are sometimes obtained in high yields by direct condensation without a metal template. Macrocycles of other sizes from this family can often be selectively obtained in high yields by a suitable choice of metal template, solvent, or chirality of the building blocks. In particular, the application of a cadmium(II) template results in the expansion of the [2 + 2] macrocycles into giant [6 + 6] and [8 + 8] macrocycles. These imine macrocycles can be reduced to the corresponding macrocyclic amines which can act as hosts for the binding of multiple cations or multiple anions.

Controllable syntheses and magnetic properties of novel homoleptic triple-decker lanthanide complexes

A class of novel triple-decker lanthanide complexes have been continuously designed and synthesized based on a Schiff base ligand Cl-salphenH₂ and precursors [(acac)₄Ln₂(L)]. The results reveal Dy complex behaves as a typical SMM with intermetallic ferromagnetic interaction.

Mononuclear and trinuclear DyIII SMMs with Schiff-base ligands modified by nitro-groups: first triangular complex with a N–N pathway

Three Dy^III SMMs were obtained with Schiff-base ligands containing nitro-groups. The triangular complex supported by the cis–trans form of the hnc³⁻ ligand displayed the first air-stable triangular complex with a N–N pathway.

Syntheses, structures and magnetic properties of macrocyclic Schiff base-supported homodinuclear lanthanide complexes

Five new homodinuclear lanthanide complexes with the general formula [(acac)4Ln2(L)] (Ln3+ = Dy3+ (1), Tb3+ (2), Ho3+ (3), Er3+ (4), and Gd (5)) were synthesized by one-pot [2 + 2] condensation of 2,6-diformyl-4-methylphenol and 1,3-diaminopropane in the presence of various lanthanide acetylacetonates. The eight-coordinate Ln(iii) centre adopts a slightly distorted square antiprism geometry with D4d symmetry. Theoretical analysis and magnetic measurements reveal that the corresponding Dy complex 1 exhibits slow magnetic relaxation behavior, characteristic of a typical SMM with the intramolecular ferromagnetic Dy3+Dy3+ interaction.

A new series of tetrahedral Co(ii) complexes [CoLX2] (X = NCS, Cl, Br, I) manifesting single-ion magnet features

The influence of ligand field strength on the magnetic anisotropy of a series of isostructural tetrahedral Co^II complexes has been investigated by using a combined experimental and theoretical approach.

Probing the Effects of Ligand Field and Coordination Geometry on Magnetic Anisotropy of Pentacoordinate Cobalt(II) Single-Ion Magnets

In this work, the effects of ligand field strength as well as the metal coordination geometry on magnetic anisotropy of pentacoordinated Co^II complexes have been investigated using a combined experimental and theoretical approach. For that, a strategic design and synthesis of three pentacoordinate Co^II complexes [Co(bbp)Cl₂]·(MeOH) (1), [Co(bbp)Br₂]·(MeOH) (2), and [Co(bbp)(NCS)₂] (3) has been achieved by using the tridentate coordination environment of the ligand in conjunction with the accommodating terminal ligands (i.e., chloride, bromide, and thiocyanate). Detailed magnetic studies disclose the occurrence of slow magnetic relaxation behavior of Co^II centers with an easy-plane magnetic anisotropy. A quantitative estimation of ZFS parameters has been successfully performed by density functional theory (DFT) calculations. Both the sign and magnitude of ZFS parameters are prophesied well by this DFT method. The theoretical results also reveal that the α → β (SOMO-SOMO) excitation contributes almost entirely to the total ZFS values for all complexes. It is worth noting that the excitation pertaining to the most positive contribution to the ZFS parameter is the d_xy → d_x²-y² excitation for complexes 1 and 2, whereas for complex 3 it is the d_z² → d_x²-y² excitation.

New sandwich-type lanthanide complexes based on closed-macrocyclic Schiff base and phthalocyanine molecules

Two new sandwich-type lanthanide complexes simultaneously containing closed-macrocyclic Schiff base and phthalocyanine molecules were synthesized and structurally characterized. The magnetic studies reveal the corresponding dysprosium complex behaves as a typical SMM.

Tetrahedral MII based binuclear double-stranded helicates: single-ion-magnet and fluorescence behaviour

It has been demonstrated that the slow relaxation of magnetization can be achieved in high spin tetrahedral Co^II centres with an easy-plane magnetic anisotropy within the double-stranded helicates. The photoluminescence properties of the Zn analogues were studied in different solvents.

Chirality detection of two enantiomorphic 3D lanthanide coordination polymers by vibrational circular dichroism spectra

Two enantiomorphic 3D lanthanide coordination polymers of {[Dy5(L)4(H2O)10][Dy(H2O)7][Na(H2O)5]}·(ClO4)7·(H2O)15 (1a for R and 1b for S) with chiral helical chains were synthesized based on an achiral ligand N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid (H3L) and Dy(ClO4)3. Crystal analysis revealed that 1a and 1b were crystallized in chiral space groups P4132 and P4332, respectively. The absolute configurations of the two structures were evidenced by vibrational circular dichroism (VCD) spectra with one single crystal sample.

Chiral mononuclear lanthanide complexes and the field-induced single-ion magnet behaviour of a Dy analogue

A rare series of enantiopure mononuclear lanthanide complex pairs were obtained by using a chiral macrocyclic ligand and thiocyanate. The Dy complex was revealed to be a rare seven-coordinated lanthanide-based SIM encapsulated in a macrocyclic ligand.