Modulation of the magnetic properties of mononuclear Dy(III) complexes by tuning the coordination geometry and local symmetry.

Precise control of the crystal field and local symmetry around the paramagnetic spin center is crucial for the design and synthesis of single-molecule magnets (SMMs). Herein, three mononuclear Dy(III)-based complexes, [Dy(L)(CHCOO)](BPh)(CHCl) (1), [Dy(L)(2,6-Cl-4-NO-PhO)(HO)](PF)(HO)(2,6-Cl-4-NO-PhO) (2) and [Dy(L)(2,6-Cl-4-NO-PhO)](BPh)(CHCl) (3) (L = N6-hexagonal plane accomplished by a neutral Schiff base ligand formed from 2,6-diacetylpyridine and ethylenediamine), are successfully isolated. In these complexes, the Dy(III) centers are coordinated with six neutral N atoms from a nonrigid equatorial ligand, while different oxygen-bearing ligands are arranged at the axial positions of the central ions by gradual regularization of the axial ligands.

Lanthanide-MOFs as multi-responsive photoluminescence sensor for sensitively detecting Fe, CrO and nitrofuran antibiotics.

Fast and selective detection of contaminants plays a key role in meeting human health and environmental concerns. Herein, two groups of isostructural lanthanide MOFs, [Ln(Hpta)(oxalic acid)]·HO (1-Eu, 2-Gd) and [Ln(pta)(oxalic acid)(HO)]·2HO (3-Eu, 4-Gd) (Hpta = 2-(4-pyridyl)-terephthalic acid, CO = oxalic acid), were synthesized by solvothermal method. Single crystal X-ray diffraction reveals that 1 and 2 are 3D neutral frameworks, while 3 and 4 consist of 2D layers with parallelogram holes and stack into 3D networks through O-H⋯N and O-H⋯O hydrogen bonding interactions.

Engineering of Stable Anionic/Neutral MOFs with Zinc-Adeninate Building Units for Efficient CH/CO Separation.

Using adenine and metal ions to form secondary building units (SBUs), further connected by a highly symmetrical multicarboxylic linker to construct an amino-modified porous framework with high porosity, is an effective strategy. By regulating the deprotonation and hydrolysis capacity of the synthesized solvent, it is possible to obtain different charged frameworks. In this work, two stable anionic/neutral MOFs, (EtNH)[Zn(TCPE)(adenine)CHCOO]·DEF·3HO () and [Zn(adenine)(TCPE)(DMA)(HO)]·2DMA·2HO (), have been synthesized based on zinc-adeninate building units and symmetric tetrakis(4-carboxyphenyl)ethylene (HTCPE) in ,-diethylformamide (DEF) and ,-dimethylacetamide (DMA) reaction systems, respectively.

A mononuclear nine-coordinated Dy(iii) complex exhibiting field-induced single-ion magnetism behaviour.

A new mononuclear Dy(iii) complex, with the formula [Dy(Hcpt)]·2HO (1), has been successfully prepared self-assembly between Dy(iii) ions and 2-cyano-'-(1-(pyridin-2-yl)amido)acetyl (Hcpt) ligand. X-ray diffraction study shows that the Dy(iii) ion is nine-coordinated by three Hcpt ligands with a tridentate chelating mode, leading to an approximately monocapped square-antiprismatic ( ) geometry. Magnetic data analysis demonstrates that 1 performs field-induced slow magnetic relaxation with a relaxation barrier of 97.

Modulation of architectures and magnetic dynamics in pseudotetrahedral cobalt(II) complexes.

Two β-Diketiminate cobalt(II) compounds of formula [LCo(μ-Cl)]·2CH (1) and [LCoClPy]·0.5CH·0.5CH (2) (L = [PhC-(PhCN-Dip)], Dip = 2,6-PrCH) have been synthesized and structurally characterized by single crystal X-ray diffraction.

Reversible on-off switching of Dy(III) single-molecule magnets single-crystal-to-single-crystal transformation.

While the interest in single-molecule magnets (SMMs) lies in their potential applications in information storage and quantum computing, the switching of their slow magnetic relaxation associated with dynamic crystal-to-crystal transformation is insufficiently exploited. Herein, three pentagonal-bipyramidal (PBP) Dy(III) complexes, [Dy(Bcpen)(Cl)] (1), [Dy(Bcpen)(OPhClNO)] (2) and [Dy(Bcpen)(OPhClNO)]·0.5CHCN (2·CH3CN), are successfully assembled, and structurally and magnetically studied (Bcpen = ,-bis(4-chloro-2-methylenepyridinyl) ethylenediamine and ClNOPhOH = 2,6-dichloro-4-nitrophenol).

Dual-sensitized Eu(III)/Tb(III) complexes exhibiting tunable luminescence emission and their application in cellular-imaging.

Two novel dual-photosensitized stable complexes, namely [Eu(dpq)(BTFA)] (1) and [Tb(dpq)(BTFA)] (2), have been successfully assembled a mixed ligand approach using dipyrido[3,2-:2',3'-]quinoxaline (dpq) and 3-benzoyl-1,1,1-trifluoroacetone (BTFA). The crystallographic data reveal mononuclear lanthanide cores in both 1 and 2, in which each eight-coordinated Ln(III) ion is located in a slightly distorted dodecahedron (). The room-temperature photoluminescence spectra of complexes 1 and 2 indicate that both BTFA and dpq can effectively sensitize Eu(III) and Tb(III) characteristic luminescence.

Two mesoporous anionic metal-organic frameworks for selective and efficient adsorption of a cationic organic dye.

Anionic metal-organic frameworks (MOFs) are beginning to have a great impact in the field of absorption and separation of ionic organic molecules due to the enhanced electrostatic interactions between their anionic frameworks and counter-ionic guests. Herein, the rational design and synthesis of two mesoporous anionic MOFs, [Zn(ITTC)](Me NH)·3DMF·HO (1) and [Cd(ITTC)](MeNH)·2DMF (2), where HITTC = 4,4',4''-(1-imidazole-2,4,5-triyl) tribenzoic acid, is reported. Structural analysis revealed that both materials are anionic MOFs with a 2-fold interpenetrating three dimensional (3D) framework.

Regulating the magnetic dynamics of mononuclear β-diketone Dy(iii) single-molecule magnets through the substitution effect on capping N-donor coligands.

A series of five mononuclear β-diketonate-Dy(iii) complexes, with formulas Dy(ntfa)(Br-bpy) (1), Dy(ntfa)(Br-bpy) (2), Dy(ntfa)(5,5-(CH)-bpy) (3), Dy(ntfa)(4,4-((CH))-bpy) (4) and Dy(ntfa)(4,4-(CH)-bpy) (5) (ntfa = 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione, Br-bpy = 5-bromo-2,2'-bipyridine, Br-bpy = 4,4'-dibromo-2,2'-bipyridine, 5,5-(CH)-bpy = 5,5'-di-methyl-2,2'-bipyridine, 4,4-((CH))-bpy = 4,4'-di-tert-butyl-2,2'-bipyridine, and 4,4-(CH)-bpy = 4,4'-di-methyl-2,2'-bipyridine), have been prepared by altering the capping N-donor coligands. Dy(iii) ions in all complexes possess NO octa-coordinated environments, displaying a distorted square antiprismatic D symmetry in complexes 1-4, as well as a triangular dodecahedron D symmetry in 5. Magnetic investigations evidence the SIM behavior in the five complexes with the energy barriers (U) of 104.

A series of lanthanide(III) metal-organic frameworks derived from a pyridyl-dicarboxylate ligand: single-molecule magnet behaviour and luminescence properties.

The reactions of LnIII ions with a versatile pyridyl-decorated dicarboxylic acid ligand lead to the formation of a series of novel three-dimensional (3D) Ln-MOFs, [Ln3(pta)4(Hpta)(H2O)]·xH2O (Ln = Dy (1), Eu (2), Gd (3), Tb (4), H2pta = 2-(4-pyridyl)-terephthalic acid, x = 6 for 1, 2.5 for 2, 1.5 for 3 and 2 for 4).

Lanthanide Metal-Organic Frameworks Assembled from Unexplored Imidazolylcarboxylic Acid: Structure and Field-Induced Two-Step Magnetic Relaxation.

A series of 3D homologous metal-organic frameworks, [M(HL)] [M = Dy (), Ho (), Yb (), Sm (), Gd (), and Y (); HL = 5-(1-imidazol-1-yl)isophthalic acid], were isolated. In these complexes, the metal centers behave as hexacoordinated environments with distorted octahedral geometries, which is unusual in the lanthanide series, linking to each other and producing a fascinating 3D architecture. Magnetically, features a field-driven dual-magnetic relaxation, which is rarely observed in high-dimensional coordination polymers.

A dual-sensitized luminescent europium(iii) complex as a photoluminescent probe for selectively detecting Fe.

A new luminescent Eu complex, namely [Eu(BTFA)(OMe)(dpq)] (1), in which BTFA = 3-benzoyl-1,1,1-trifluoroacetone and dpq = dipyrido [3,2-:2',3'-] quinoxaline, has been designed and synthesized by employing two different ligands as sensitizers. Crystal structure analysis reveals that complex 1 is composed of dinuclear Eu units crystallized in the monoclinic 1̄ space group. Notably, 1 exhibits high thermal stability up to 270 °C and excellent water stability.

Modulating energetic performance through decorating nitrogen-rich ligands in high-energy MOFs.

In the presence of different nitrogen-rich ligands, two energetic MOFs with formulas [Ag(tza)] (1) and [Ag(atza)] (2) (Htza = tetrazole-1-acetic acid and Hatza = (5-amino-1H-tetrazole-1-yl) acetic acid) were successfully synthesized and characterized. X-ray single crystal structure analysis shows that both 1 and 2 have 2D layer-like topologies. The experimental and theoretical evaluations reveal the promising properties of both energetic compounds, such as prominent heats of detonation, high thermal stabilities, good sensitivities and excellent detonation performances.

Modulating magnetic dynamics through tailoring the terminal ligands in Dy single-molecule magnets.

Complexation of dysprosium(iii) ions with a multidentate hydrazone ligand, N-[(E)-pyridin-2-ylmethylideneamino]pyridine-2-carboxamide (L), in the presence of different β-diketonate coligands, leads to the formation of two novel DyIII dimers, with formulas Dy2(BTFA)4(L)2 (1) and Dy2(TTA)4(L)2 (2) (BTFA = 3-benzoyl-1,1,1-trifluoroacetone and TTA = 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedionate). They exhibit slightly different coordination geometries around DyIII centers and discrepant binuclear motifs - as a result of altering the β-diketonate coligands - which has an impact on the magnetic interactions between metal centers, the local tensor of anisotropy on each DyIII site and their relative orientations, therefore contributing to distinct magnetization dynamics. Compared to 2, complex 1 exhibits a more significant slow magnetic relaxation of SMM behavior in the absence of a dc field.

Capping N-Donor Ligands Modulate the Magnetic Dynamics of Dy β-Diketonate Single-Ion Magnets with D Symmetry.

A family of four mononuclear Dy β-diketonate complexes with formulas [Dy(tmhd) (Br -bpy) (1), [Dy(tmhd) (Br-bpy)] (2), [Dy(tmhd) (dppz)] (3), and [Dy(tmhd) (mcdpq)] (4) (tmhd=2,2,6,6-tetramethyl-3,5-heptanedione, Br -bpy=5,5'-dibromo-2,2'-bipyridine, Br-bpy=5-bromo-2,2'-bipyridine, dppz=dipyrido [3,2-a:2',3'-c]phenazine, mcdpq=2-methoxyl-3-cyanodipyrido[3,2-f:2,3'-h]quinoxaline) were prepared by modifying the capping N-donor coligands. Dy centers in these complexes feature an N O octacoordinate environment with distorted square-antiprismatic D symmetry. Magnetic investigations evidenced single-ion magnet behavior in all complexes with energy barriers U of 42.

Concise Chemistry Modulation of the SMM Behavior within a Family of Mononuclear Dy(III) Complexes.

By means of the facile chemistry, structural assembly, and transformation of four mononuclear Dy(III) complexes, Dy(bpad)·CHOH·HO (1), Dy(bpad)(HO)·NO (2), [Dy(bpad)(tmhd)] (3), and [Dy(bpad)(btfa)] (4) (Hbpad = N-benzoylpyridine-2-carboxamidrazone, tmhd = 2,2,6,6-tetramethylheptane-3,5-dione, btfa = 3-benzoyl-1,1,1-trifluoroacetone), with distinct architectures and local symmetries were established. The disparity of the coordination geometries around the Dy(III) ion among these complexes impacts the strength of the crystal field and the local tensor of anisotropy ( D) of each Dy site and their relative orientations, therefore giving rise to diverse SIM behaviors with distinguishing relaxation energy barriers of 106.93 K for 1, 52.

A substituent effect of phenylacetic acid coligand perturbed structures and magnetic properties observed in two triple-bridged azido-Cu(ii) chain compounds with ferromagnetic ordering and slow magnetic relaxation.

Based on two fluoro-substituted phenylacetate isomers, o-fluorophenylacetic acid (o-Hfpa) and p-fluorophenylacetic acid (p-Hfpa), two new Cu(ii)-azido compounds, [Cu(o-fpa)(N)(CHOH)] (1) and [Cu(p-fpa)(N)(CHOH)] (2), have been prepared, and structurally and magnetically characterized. Single-crystal structure analyses indicate that compounds 1 and 2 consist of 1D chain-like coordination networks in which adjacent copper cations are linked by the alternating triple-bridges of μ-1,1-azido, syn,syn-carboxylate and μ2-ethanol. For the two title compounds, the diverse charge distributions on the carboxyl groups caused by distinct substituent effects of the two phenylacetate coligands lead to the different structural parameters of intrachain Cu-Cu distances (3.

Tuning of Exchange Coupling and Switchable Magnetization Dynamics by Displacing the Bridging Ligands Observed in Two Dimeric Manganese(III) Compounds.

Two Mn(III)-based dimers, [Mn(bpad)(CHO)] (1) and [Mn(bpad)(pa)]·2HO (2) (Hbpad = N-benzoylpyridine-2-carboxamidrazone, Hpa = phthalic acid), have been assembled from a tridentate Schiff-base chelator and various anionic coligands. Noteworthily, compound 1 could be identified as a reaction precursor to transform to 2 in the presence of phthalic acid, resulting in a rarely structural conversion process in which the bridges between intradimer Mn(III) ions alter from methanol oxygen atom with μ-O mode in 1 (Mn Mn distance of 3.046 Å) to syn-anti carboxylate in 2 (Mn Mn distance of 4.

Electrostatic Potential Determined Magnetic Dynamics Observed in Two Mononuclear β-Diketone Dysprosium(III) Single-Molecule Magnets.

Two β-diketone mononuclear Dy(III) compounds, formulated as Dy(BTFA)(HO) (1) and Dy(BTFA)(bpy) (2) (BTFA = 3-benzoyl-1,1,1-trifluoroacetone, bpy = 2,2'-bipyridine), were prepared. Compound 1 can be identified to transform to 2 in the attendance of bpy coligand, when the local geometry symmetry of eight-coordinated Dy(III) ion changes from a dodecahedron (D) in 1 to a square antiprism (D) in 2. Fine-tuning structure aroused by auxiliary ligand has dramatical impact on magnetic properties of compounds 1 and 2.

Coligand modifications fine-tuned the structure and magnetic properties of two triple-bridged azido-Cu(ii) chain compounds exhibiting ferromagnetic ordering and slow relaxation.

Employing two benzoate derivatives with different numbers of non-coordinated fluoro-substituents, 2-fluorobenzoic acid (2-Hfba) and 2,6-difluorobenzoic acid (2,6-Hdfba), two new azido-copper coordination polymers, [Cu(2-fba)(N)(CHOH)] (1) and [Cu(2,6-dfba)(N)(CHOH)] (2), have been successfully isolated, and then structurally and magnetically investigated. Single crystal structure analysis demonstrates that the metal cations in the two resulting compounds are connected by the alternating triple-bridge of μ-1,1-azido, syn,syn-carboxylate and μ2-methanol, contributing to analogously linear 1D Cu(ii) chain-like motifs with slightly different intrachain and interchain geometric parameters. The fine-tuned structures lead to variant magnetic properties in the two title compounds.

Single-ion-magnet behavior in a two-dimensional coordination polymer constructed from Co(II) nodes and a pyridylhydrazone derivative.

A novel two-dimensional (2D) coordination polymer, [Co(ppad)2]n (1), resulted from the assembly of Co(II) ions based on a versatile ligand termed N(3)-(3-pyridoyl)-3-pyridinecarboxamidrazone. Alternating/direct-current magnetic studies of compound 1 indicate that the spatially separated high-spin Co(II) ions act as single-ion magnets (SIMs). The present work represents the first case of a 2D Co(II)-based SIM composed of a monocomponent organic spacer.

Solvent-induced syntheses, crystal structures, magnetic properties, and single-crystal-to-single-crystal transformation of azido-Cu(II) coordination polymers with 2-naphthoic acid as co-ligand.

Based on the solvent-induced effect, three new azido-copper coordination polymers--[Cu(2-na)(N3)] (1), [Cu(2-na)(N3)] (2), and [Cu(2-na)(N3)(C2H5OH)] (3) (where 2-na = 2-naphthoic acid)--have been successfully prepared. Structure analysis shows that the Cu(II) cations in compounds 1-3 present tetra-, penta-, and hexa-coordination geometries, respectively. Compound 1 is a well-isolated one-dimensional (1D) chain with the EO-azido group, while 2 is an isomer of 1 and exhibits a two-dimensional (2D) layer involving the EE-azido group.