High temperature quantum tunnelling of magnetization and thousand kelvin anisotropy barrier in a Dy single-molecule magnet.

We report here a dinuclear DyIII iodine-bridged single-molecule magnet self-assembled by cis/trans coordination chemistry that displays a large anisotropy barrier of ca. 1300 K and a hysteresis opening temperature of 16 K. High temperature quantum tunnelling of magnetization is observed up to 56 K in zero-field and explained by the combination of the large anisotropy barrier and the local transverse field at the trans site.

Synergistic effect of mixed ligands on the anisotropy axis of two dinuclear dysprosium complexes.

We present the syntheses, crystal structures, magnetic properties and theoretical calculations performed on two dinuclear dysprosium complexes with formulas Dy(L)(L)(CHCHOH)(CHOH) (1) and Dy(L)(L)(CHOH)·1.5CHOH (2). Single-crystal X-ray structural data analyses showed that both complexes contain two nonequivalent dysprosium ions bridged by two phenolate oxygen atoms.

An Inconspicuous Six-Coordinate Neutral Dy Single-Ion Magnet with Remarkable Magnetic Anisotropy and Stability.

It is a crucial challenge to address both magnetic anisotropy and stability for single-molecule magnets (SMMs) used in next-generation nanodevices. Highly axial lanthanide SMMs with neutral charge and moderate coordination numbers represent promising magnetic materials. Here, using iodide ions with large volume and low surface charge density as weak donors, we report a six-coordinate neutral dysprosium SMM [Dy(CyPO)I(CHCN)] with a certain degree of stability exhibiting a huge thermal barrier of 1062 K and hysteresis loops open up to 9 K.

A Trinuclear Zinc Coordination Cluster Exhibiting Fluorescence, Colorimetric Sensitivity, and Recycling of Silver Ion and Detection of Cupric Ion.

The detection and reusage of transition-metal ions play a crucial role in human health and environmental protection. Recently, various analytical methods and substances have been successfully applied to probe or sense silver ions; however, rare representative examples have been presented regarding the simultaneous detection of silver and silver recycling with the elemental silver powder form. Herein, an unparalleled sensing mechanism for silver ions and recycling silver in its elemental form is exemplified by a fluorescent trinuclear zinc coordination cluster possessing the dual function of colorimetric sensing of silver and responding cupric ions.

Solvent-tuned magnetic exchange interactions in Dy systems ligated by a μ-phenolato heptadentate Schiff base.

A series of binuclear dysprosium compounds, namely, [Dy(api)] (1), [Dy(api)]·2CHCl (2), [Dy(Clapi)]·2CHO (3), and [Dy(Clapi)]·2CHO (4) (Hapi = 2-(2-hydroxyphenyl)-1,3-bis[4-(2-hydroxyphenyl)-3-azabut-3-enyl]-1,3-imidazoline; HClapi = 2-(2'-hydroxy-5'-chlorophenyl)-1,3-bis[3'-aza-4'-(2''-hydroxy-5''-chlorophenyl)prop-4'-en-1'-yl]-1,3-imidazolidine), have been isolated by the reactions of salen-type ligands Hapi/HClapi with DyCl·6HO in different solvent systems. Structural analysis reveals that each salen-type ligand provides a heptadentate coordination pocket (NO) to encapsulate a Dy ion and all of the Dy centers in 1-4 adopt a distorted square antiprism geometry with symmetry. Magnetic studies showed that compound 1 did not exhibit single-molecule magnetic (SMMs) behavior.

Bromine-bridged Dy single-molecule magnet: magnetic anisotropy driven by cis/trans stereoisomers.

We report the first bromine-bridged dinuclear [Dy(CyPO)(μ-Br)(Br)]·2CH single-molecule magnet with an effective energy barrier of 684 K and magnetic hysteresis below 3 K. The asymmetric Dy centres present two unique stereoisomeric octahedral coordination environments depending on the cis/trans disposition of the CyPO ligands, leading to the orthogonality of the easy magnetic axes that annihilates the dipolar interactions.

Fine-tuning the type of equatorial donor atom in pentagonal bipyramidal Dy(iii) complexes to enhance single-molecule magnet properties.

A family of new structurally manipulable pentagonal-bipyramidal (PBP) Dy SMMs, with formulas [Dy(Hbpen)(Cl)] (1), [Dy(Hbpen)Cl(OPhBrNO)] (2), [Dy(Hbpen)(OPhClNO)] (3) and [Dy(Mbpen)(Cl)] (1CH), were controllably prepared based on a H-substituted amine-based ligand N,N'-bis(2-pyridylmethyl)-ethylenediamine (Hbpen) or a CH-substituted amine-based ligand N,N'-dimethyl-N,N'-bis(2-pyridylmethyl)-ethylenediamine (Mbpen) and are compared with the reported imine-based Dy analogues (1'-3'). Upon fine-modulating the type of nitrogen donor on the pentagon plane, the electronic effect is efficiently implemented to significantly modify the magnetic anisotropy and SMM behavior of PBP complexes. Notably, the amine-based 2 shows a three-fold improved energy barrier and an observable hysteresis opening up to 3 K.

Effect of coordination anion substitutions on relaxation dynamics of defect dicubane ZnDy tetranuclear clusters.

We showcase the coordination anion substitution effect on the relaxation dynamics of defect dicubane ZnDy tetranuclear clusters. On utilization of the coordination similarity of acetate and nitrate anions, we successfully isolated two defect dicubane ZnDy tetranuclear clusters with formulas [ZnDy(L)(NO)(CHOH)]·2CHCOCH (1) and [ZnDy(L)(CHCOO)(CHCHOH)]·4CHCOCH (2), where L denotes the fully deprotonated HL ligand (E)-4-(tert-butyl)-2-((2-hydroxy-3-methoxybenzylidene)amino)phenol. Such a subtle change in the coordination anion around the Dy site imposes a significant effect on the distinct relaxation dynamics in 1 and 2.

Influence of alcoholic solvent and acetate anion coordination mode variations on structures and magnetic properties of heterometallic ZnDy tetranuclear clusters.

The present work clarifies how slight modifications of the synthetic conditions (e.g., employment of different alcoholic solvents) can result in the variation of the coordination mode of an acetate anion yielding two structurally similar heterometallic Zn2Dy2 tetranuclear clusters with formulas [Zn2Dy2(L)4(CH3COO)2(CH3CH2OH)2]·2CH2Cl2·0.

Two {ZnDy} complexes supported by monophenoxido/dicarboxylate bridges with multiple relaxation processes: carboxylato ancillary ligand-controlled magnetic anisotropy in square antiprismatic Dy species.

Two linear-shaped heterometallic trinuclear {ZnII2DyIII} clusters were prepared with a compartmental Schiff-base ligand and carboxylate as the co-ligand. The central DyIII ion is sandwiched by two [ZnHhms(RCOO)2] (H2hms = (2-hydroxy-3-methoxybenzylidene)-semicarbazide) units to form a distorted square antiprismatic (SAP) geometry with D4d symmetry. The DyIII and ZnII ions are triply bridged by one unique monophenoxido/dicarboxylate group, where one of the carboxylates shows a severe angular distortion.

Experimental and Theoretical Interpretation on the Magnetic Behavior in a Series of Pentagonal-Bipyramidal Dy Single-Ion Magnets.

Taking advantage of the steric hindrance and charge-driving effects, four air-stable pentagonal bipyramidal mononuclear Dy compounds were hydrothermally synthesized. With a tetradentate ligand, N,N'-bis(2-methylenepyridinyl)ethylenediamine (Bpen), invariably coordinates to Dy in an equatorial plan, 1-3 achieve an orderly transformation of the ligand field by sequentially replacing the remaining sites of the Dy ion. Compound 4 possesses the same coordination atoms but a different peripheral coordination sphere with 3.

Magnetic Interaction Affecting the Zero-Field Single-Molecule Magnet Behaviors in Isomorphic {NiDy} and {CoDy} Tetranuclear Complexes.

Great interest is being shown in investigating magnetic interactions that efficiently influence lanthanide single-molecule magnet behavior. A series of heterometallic complexes [MLn(Hhms)(CHCOO)(CHOH)(HO)]·(NO) (M = Ni, Ln = Dy (1), Gd (2), and Y (3); M = Co, Ln = Dy (4), Gd (5), and Y (6)) have been prepared with a compartmental Schiff-base ligand, 1-(2-hydroxy-3-methoxybenzylidene)-semicarbazide (Hhms), featuring a zigzag-shaped M-Ln-Ln-M metallic core arrangement. In complexes 1-6, a unique monophenoxo/diacetate asymmetric bridging connects M ion with Ln ion, and four acetates bridge two Ln ions where acetates play essential roles as coligand in generating the tetranuclear units.

Unusual undecanuclear heterobimetallic ZnLn (Ln = Gd, Dy) nano-sized clusters encapsulating two peroxide anions through spontaneous intake of dioxygen.

The synthesis, characterization and properties of two unprecedented undecanuclear heterobimetallic ZnLn complexes of formula [ZnLn(L)(O)(OH)(Cl)(HO)]·Cl·4HO·4CHCN (Ln = Gd (1), Dy (2)) encapsulating two peroxide anions are presented, representing a very rare example of a 3d-peroxo-Ln system and expanding the realm of metal-peroxo complexes. These eleven metal ions are arranged in a peculiar structural motif, where Zn is located at the peripheral shell wrapping Ln in the inner core. The Zn ions are penta-coordinate in all cases, linked to the NO donor atoms from the L ligand and to a hydroxyl group, and the apical position is occupied by a chloride anion.

Low temperature heat capacity, standard entropy, standard enthalpy and magnetic property: a new 1D Cu coordination polymer incorporating tetrazole-1-acetic acid and p-nitrobenzoic acid.

A new 1D Cu coordination polymer, formulated as {[Cu(TZA)(PNA)]·HO} (1) (HTZA = tetrazole-1-acetic acid, HPNA = p-nitrobenzoic acid), was synthesized and structurally characterized. Thermogravimetric analysis demonstrated that the main frame of 1 exhibited good thermostability up to 473 K. The non-isothermal kinetics for the first exothermic process of 1 were studied by Kissinger and Ozawa methods.

Magnetization Dynamics Changes of Dysprosium(III) Single-Ion Magnets Associated with Guest Molecules.

Two Dy(III) single-ion magnets with a trigonal dodecahedron (D2d) for 1 and an approximately square-antiprismatic (SAP, D4d) N2O6 coordination environment for 2, formulated as [Dy(Phen)(tfmb)3] (1) and [Dy(Phen)(tfmb)3]·0.5(1,4-dioxane) (2) (tfmb = 4,4,4-trifluoro-1-(4-methylphenyl)-1,3-butanedione, Phen = 1,10-phenanthroline), were obtained. Therein, complex 1 was transformed to 2 in 1,4-dioxane solution.

Dysprosium(III) complexes with a square-antiprism configuration featuring mononuclear single-molecule magnetic behaviours based on different β-diketonate ligands and auxiliary ligands.

Three mononuclear dysprosium(III) complexes derived from three β-diketonate ligands, 4,4,4-trifluoro-1-(4-methylphenyl)-1,3-butanedione (tfmb), 4,4,4-trifluoro-1-(4-fluorophenyl)-1,3-butanedione (tffb) and 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione (tfnb) as well as auxiliary ligands, 5-nitro-1,10-phenanthroline (5-NO2-Phen), DMF and 2,2'-bipyridine (bpy) have been synthesized and structurally characterized, namely [Dy(5-NO2-Phen)(tfmb)3] (1), [Dy(DMF)2(tffb)3] (2) and [Dy(bpy)2(tfnb)3]·0.5(1,4-dioxane) (3). The metal ions in 1-3 adopt an approximately square-antiprismatic (SAP) coordination environment with D4d axial symmetry.

High-Performance Energetic Characteristics and Magnetic Properties of a Three-Dimensional Cobalt(II) Metal-Organic Framework Assembled with Azido and Triazole.

A three-dimensional metal-organic framework based, high-energy-density compound, [Co5(3-atrz)7(N3)3] (3-atrz = 3-amine-1H-1,2,4-triazole), features superior detonation properties, insensitivity, and thermostability. Magnetic studies show that the compound characterizes the coexistence of remarkable coercivity, metamagnetism, long-range ordering, and relaxation dynamics. The heat-capacity measurement confirms the typical long-range antiferromagnetic ordering below 16 K.

A Dy2 single-molecule magnet with benzoate anions and phenol-O(-) bridging groups.

A Dy2 single-molecule magnet, namely [Dy2(H3L)2(PhCOO)4]·4H2O (1), was obtained from the reaction of Dy(PhCOO)3 with 1,5-bis(2-hydroxy-3-methoxybenzylidene)carbonohydrazide (H4L). Each Dy(III) ion is located in the chelating pocket [DyO8N] formed by the carboxyl-O, phenol-O, carbohydrazide-O and carbohydrazide-N, forming a tricapped trigonal prism configuration. The Dy(III) centers are bridged by the benzoate anions with μ2:η(1),η(2) coordination mode and the phenol-O(-) groups in the form of μ1:η(2), respectively.

A nine-coordinated dysprosium(III) compound with an oxalate-bridged dysprosium(III) layer exhibiting two slow magnetic relaxation processes.

A 2D oxalate-bridged dysprosium(III) compound, formulated as [Dy(C2O4)1.5(H2O)3]n·2nH2O (1), has been hydrothermally isolated. As for compound 1, structural analysis reveals that the nine-coordinated Dy(III) ions reside in a slightly distorted tricapped trigonal prism.

A triple-bridged azido-Cu(II) chain compound fine-tuned by mixed carboxylate/ethanol linkers displays slow-relaxation and ferromagnetic order: synthesis, crystal structure, magnetic properties and DFT calculations.

A new azido-Cu(II) compound, [Cu(4-fba)(N3)(C2H5OH)] (4-fba = 4-fluorobenzoic acid) (1), has been synthesized and characterized. The X-ray crystal structure analysis demonstrates that only one crystallographically independent Cu(II) ion in the asymmetric unit of 1 exhibits a stretched octahedral geometry in which two azido N atoms and two carboxylic O atoms locate in the equatorial square, while two ethanol O atoms occupy the apical positions, forming a 1D Cu(II) chain with an alternating triple-bridge of EO-azido, syn,syn-carboxylate, and μ2-ethanol. The title compound consists of ferromagnetically interacting ferromagnetic chains, which exhibit ferromagnetic order (T(c) = 7.

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.

Family of defect-dicubane Ni4Ln2 (Ln = Gd, Tb, Dy, Ho) and Ni4Y2 complexes: rare Tb(III) and Ho(III) examples showing SMM behavior.

Reactions of Ln(III) perchlorate (Ln = Gd, Tb, Dy, and Ho), NiCl2·6H2O, and a polydentate Schiff base resulted in the assembly of novel isostructural hexanuclear Ni4Ln2 complexes [Ln = Gd (1), Tb (2), Dy (3), Ho (4)] with an unprecedented 3d-4f metal topology consisting of two defect-dicubane units. The corresponding Ni4Y2 (5) complex containing diamagnetic Y(III) atoms was also isolated to assist the magnetic studies. Interestingly, complexes 2 and 3 exhibit SMM characteristics and 4 shows slow relaxation of the magnetization.

Heterometallic octanuclear RE(III)3Ni(II)5 (RE = Dy(III), Gd(III) and Y(III)) clusters with slow magnetic relaxation for the dysprosium derivative.

Reactions of rare earth benzoate and nickel perchlorate with a Schiff-base ligand, 2-([(2-hydroxyphenyl)imino]methyl) phenol (H2L), in the presence of triethylamine yielded three heterobimetallic octanuclear clusters of general formula [RE3Ni5L5(PhCOO)3(μ3-OH)5(μ3-OCH3)(CH3OH)4(H2O)]·xCH3OH·yH2O (RE = Dy(III), x = 4, y = 4 (1), RE = Gd(III), x = 5, y = 4 (2), RE = Y(III), x = 5, y = 3 (3)). Single-crystal X-ray diffraction reveals that the metal core of each cluster consists of two distorted [RE2Ni2O4] cubane-like moieties and a heterobimetallic triangular [RE2NiO2] unit, with RE ions arranged in a typical triangular fashion. Variable-temperature solid state magnetic susceptibilities of these complexes were measured in the temperature range 2-300 K and the results indicate that an overall ferromagnetic interaction among the metal ions is operative for compounds 2 and 3.

Polydentate-ligand-supported self-assembly of heterometallic T-shaped Co4RE (RE = Gd, Tb, Y) clusters: synthesis, structure and magnetism.

A series of mixed-valent heterometallic pentanuclear Co(III)(3)Co(II)RE(III) (RE = Gd (1), Tb (2), Y (3)) clusters have been rationally assembled by taking advantage of a bifunctional ligand with o-vanillin and tripodal tris(hydroxymethyl)aminomethane units. Structural determinations reveal that all compounds are isomorphous and possess a T-shaped Co(4)RE core, which comprises two nearly linear Co(2)RE subunits sharing a common RE ion. Their magnetic properties were thoroughly studied.