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In this work, we describe the synthesis, crystal structures and magnetic properties of four air-stable mononuclear lanthanide(III) complexes with the N-(2,4,6-trimethylphenyl)oxamate (Htmpa) of formula: n-Bu4N[Nd(Htmpa)4(H2O)]·4H2O (1), n-Bu4N[Gd(Htmpa)4(H2O)]·3DMSO·2H2O (2), n-Bu4N[Tb(Htmpa)4(H2O)]·3DMSO·1H2O (3) and n-Bu4N[Dy(Htmpa)4(H2O)]·3DMSO·2H2O (4) (n-Bu4N+ = n-tetrabutylammonium; DMSO = dimethylsulfoxide). Their crystal structures reveal the occurrence of calixarene-type monoanionic species containing all-cis-disposed Htmpa ligands and one water molecule coordinated with the respective LnIII ion (Ln = Nd, Gd, Tb and Dy), featuring a nine-coordinated environment with muffin (MFF-9) (1) or spherical-capped square antiprism (CSAPR-9) (2–4) geometry. The major difference between their crystal structures is related to the nature of crystallization solvent molecules, either water (1) or both DMSO and water (2–4). The intermolecular hydrogen bonds among the self-complementary Htmpa ligands in all four compounds mediated a 2 D supramolecular network in the solid state. Direct-current (dc) magnetic properties for 1–4 show typical behavior for the ground state terms of the LnIII ions [4I9/2 (Nd); 8S7/2(Gd), 7F6 (Tb), 6H15/2 (Dy)]. Alternating-current (ac) magnetic measurements reveal the presence of slow magnetic relaxation without the presence of a dc field only for 4. In contrast, field-induced slow magnetic relaxation behavior was found in complexes 1, 2 and 3. [ABSTRACT FROM AUTHOR]

We have prepared and characterized three coordination polymers formulated as [Dy2(C6O4Cl2)3(fma)6] ⋅ 4.5fma (1) and [Dy2(C6O4X2)3(fma)6] ⋅ 4fma ⋅ 2H2O with X=Br (2) and Cl (3), where fma=formamide and C6O4X22−=3,6‐disubstituted‐2,5‐dihydroxy‐1,4‐benzoquinone dianion with X=Cl (chloranilato) and Br (bromanilato). Compounds 1 and 3 are solvates obtained with slow and fast precipitation methods, respectively. Compounds 2 and 3 are isostructural and only differ in the X group of the anilato ligand. The three compounds present (6,3)‐gon two‐dimensional hexagonal honey‐comb structures. Magnetic measurements indicate that the three compounds show slow relaxation of the magnetization at low temperatures when a continuous magnetic field is applied, although with different relaxation times and energy barriers depending on X and the crystallisation molecules. Compounds 1–3 represent the first examples of anilato‐based lattices with formamide and field‐induced slow relaxation of the magnetization. [ABSTRACT FROM AUTHOR]

The complex formation of the redox-active ligand bis(N,N'-2,6-diisopropylphenyl)-9,10-phenanthrenediimine (DippPDI) with alkaline metal (Li, K) and lanthanide (Sm, Dy) cations is studied. The reduction of DippPDI with an alkaline metal excess affords the dianionic form of the ligand (DippPDA2–), which crystallizes with the potassium cation as the coordination polymer [K2(DippPDA)(Thf)3] (Thf is tetrahydrofuran). The reaction of equimolar amounts of the lithium salt with the dianionic form of the ligand and neutral diimine affords the lithium complex with the radical-anion form (DippPSI•–) crystallized as [Li(DippPSI)(Thf)2]. The samarium(III) complex [SmCp*(DippPDA)(Тhf)] (I) is formed by the reduction of DippPDI with samarocene [Sm (Thf)2] (Cp* is pentamethylcyclopentadienide): both the samarium(II) cation and Cp*– anion are oxidized in the reaction. DippPDI does not react with similar ytterbocene. The dysprosium(III) complexes are synthesized by the ion exchange reactions between DyI3(Thf)3.5 and potassium or lithium salt with the DippPDA2– dianion. Similar complexes [Dy(DippPDA)I(Thf)2] (IIThf) and [Dy(DippPDA)I(Thf)(Et2O)] () are formed in the reactions with the potassium salt depending on the solvent used: a THF–hexane or a diethyl ether–n-hexane mixture, respectively. The coordination of the dysprosium cation by the π system of the conjugated fragment of the NCCN ligand is observed in IIThf, whereas in this coordination is absent. The reaction with Li2(DippPDA) affords the binary complex salt [Li(Тhf)3(Et2O)][DyI2(DippPDA)(Тhf)] (III, crystallization from a THF–Et2O mixture). The crystallization from THF gives the [Li(Тhf)4][DyI2(DippPDA)(Thf)] salt (III') containing the same anion as III. The structures of all new complexes are studied by X-ray diffraction (XRD, CIF files CCDC nos. 2260307–2260313). [ABSTRACT FROM AUTHOR]

The reaction of [Ln(btfa)3(H2O)2] (btfa− = 4,4,4-trifluoro-1-phenyl-1,3-butanedionate) with additional 4,4,4-trifluoro-1-phenyl-1,3-butanedione (Hbtfa) and acridine (Acr) in ethanol allows the isolation of the mononuclear compounds HAcr[Nd(btfa)4]·EtOH, (1) and HAcr[Ln(btfa)4], Ln = Dy (2) and Yb (3); HAcr+ = acridinium cation. Magnetic measurements indicate that complexes 1–3 show field-induced single-ion magnet behavior with anisotropy energy barriers and preexponential factors of Ueff = 20.7 cm−1, τ0 = 24.5 × 10−8 s; Ueff = 40.5 cm−1, τ0 = 8.6 × 10−10 s and Ueff = 22.7 cm−1, τ0 = 8.4 × 10−8 s, for 1–3 respectively. The solid-state luminescence emission in the NIR region shows efficient energy transfer from the 4,4,4-trifluoro-1-phenyl-1,3-butanedionate ligands to the central Ln3+ ion in the case of compounds 1 and 3. [ABSTRACT FROM AUTHOR]

A new molecular conductor of (TMTSF)5[Dy(NCS)4(NO3)2]CHCl3 was prepared using the electrochemical oxidation method. The complex crystallizes in the Cmc21 (36) space group, where the partially-oxidized TMTSF molecules form a 1D (one-dimensional) column structure. The crystal shows a semiconducting behavior with a room temperature conductivity of 0.2 S·cm−1 and an activation energy of 34 meV at ambient pressure. [ABSTRACT FROM AUTHOR]

The NMR spectra of complex [Dy(DTPA)]2– are studied at various temperatures and pH values of the aqueous solution. The NMR signals of [Dy(DTPA)]2– are most sensitive to temperature changes (the maximum temperature sensitivity is 2.2 ppm/K at pH = 7.4) and are almost insensitive to pH changes in the range from 3.3 to 11.0. A significant change of chemical shifts is observed only in the pH region from 3.3 to 1.1 due to the formation of protonated forms of the complexes. [Dy(DTPA)]2– can be considered as a promising reagent for temperature determination in aqueous media using in vitro and in vivo NMR. [ABSTRACT FROM AUTHOR]

The reaction of [Ln(btfa)3(H2O)2] (btfa− = 4,4,4-trifluoro-1-phenyl-1,3-butanedionate) with additional 4,4,4-trifluoro-1-phenyl-1,3-butanedione (Hbtfa) and acridine (Acr) in ethanol allows the isolation of the mononuclear compounds HAcr[Nd(btfa)4]·EtOH, (1) and HAcr[Ln(btfa)4], Ln = Dy (2) and Yb (3); HAcr+ = acridinium cation. Magnetic measurements indicate that complexes 1–3 show field-induced single-ion magnet behavior with anisotropy energy barriers and preexponential factors of Ueff = 20.7 cm−1, τ0 = 24.5 × 10−8 s; Ueff = 40.5 cm−1, τ0 = 8.6 × 10−10 s and Ueff = 22.7 cm−1, τ0 = 8.4 × 10−8 s, for 1–3 respectively. The solid-state luminescence emission in the NIR region shows efficient energy transfer from the 4,4,4-trifluoro-1-phenyl-1,3-butanedionate ligands to the central Ln3+ ion in the case of compounds 1 and 3.

A new molecular conductor of (TMTSF)5[Dy(NCS)4(NO3)2]CHCl3 was prepared using the electrochemical oxidation method. The complex crystallizes in the Cmc21 (36) space group, where the partially-oxidized TMTSF molecules form a 1D (one-dimensional) column structure. The crystal shows a semiconducting behavior with a room temperature conductivity of 0.2 S·cm−1 and an activation energy of 34 meV at ambient pressure.

Precise control of the crystal field and symmetry around the paramagnetic spin centre has recently facilitated the engineering of high‐temperature single‐ion magnets (SIMs), the smallest possible units for future spin‐based devices. In the present work, we report a series of air‐stable seven coordinate Dy(III) SIMs {[L2Dy(H2O)5][X]3⋅L2⋅n(H2O), n = 0, X = Cl (1), n=1, X = Br (2), I (3)} possessing pseudo‐D5h symmetry or pentagonal bipyramidal coordination geometry with high anisotropy energy barrier (Ueff) and blocking temperature (TB). While the strong axial coordination from the sterically encumbered phosphonamide, tBuPO(NHiPr)2 (L), increases the overall anisotropy of the system, the presence of high symmetry significantly quenches quantum tunnelling of magnetization, which is the prominent deactivating factor encountered in SIMs. The energy barrier (Ueff) and the blocking temperature (TB) decrease in the order 3>2>1 with the change of anions from larger iodide to smaller strongly hydrogen‐bonded chloride in the secondary coordination sphere, albeit the local coordination geometry and the symmetry around the Dy(III) display only slight deviations. Ab initio CASSCF/RASSI‐SO/SINGLE_ANISO calculations provide deeper insights into the dynamics of magnetic relaxation in addition to the role of the secondary coordination sphere in modulating the anisotropy of the D5h systems, using diverse models. Thus, in addition to the importance of the crystal field and the symmetry to obtain high‐temperature SIMs, this study also probes the significance of the secondary coordination sphere that can be tailored to accomplish novel SIMs. [ABSTRACT FROM AUTHOR]

The formation of imidazolidines from secondary amines and aldehydes is well known. This small cycle can act as a nitrogen donor, and it is usually stable when it coordinates to metal ions. Sometimes, imidazolidines acting as ligands undergo breaking of the C-N bond when coordinating to the metal center, yielding related amines. However, the reorganization of the imidazolidine into a piperazine ring is quite an unusual process. In this work, we describe the transformation of a zinc complex with a ligand containing two imidazolidine moieties into a zinc complex with a piperazine fragment as donor, in the presence of a dysprosium salt.

The crystal structure of the [DyCl2(H2O)6]Cl complex is studied by X-ray diffraction analysis. The crystals are constructed of complex cations [DyCl2(H2O)6]+ and outer-sphere Cl−1 ions. The structure is represented by separate [DyCl2(H2O)6] complexes bound by a dense network of hydrogen bonds. The coordination polyhedron of Dy(III) with coordination number 8 is represented by a weakly distorted square antiprism. The results of investigation of the luminescent properties of the complex are presented. [ABSTRACT FROM AUTHOR]

The search for mononuclear lanthanoid-based single-ion magnets (SIMs) has increased the interest in some coordination environments with low coordination numbers, in combination with an axial symmetry, as they could maximize the anisotropy of complexes of oblate lanthanoid ions, such as dysprosium(III). In this sense, the pentagonal–bipyramid geometry can have ground-state doublets with perfect axiality, and therefore such complexes can be good candidates for SIMs. In our particular case, we have used a well-known open planar pentadentate chelating Schiff base ligand as 2,6-bis(1-salicyloylhydrazonoethyl)pyridine) (H4daps) for the synthesis of air-stable pentagonal–bipyramidal LnIII complexes (these being Ln: Dy and Er, oblate and prolate, respectively), in order to compare their structures. Thus, the reaction of H4daps with (CH3)4NOH·5H2O and the corresponding LnCl3·hexahydrate has yielded heptacoordinate [(CH3)4N][LnIII(H2daps)Cl2] complexes, where the tetramethylammonium cation is acting as the counterion of pentagonal–bipyramidal LnIII complexes, which are bearing two chloride atoms in apical positions. As both complexes could be crystallized as single crystals, we can compare their crystal structures, as well as with some other related complexes in the literature, which contain different counterions, trying to see their influence on other properties of the compounds, such as their magnetic behavior.

The reaction between Dy(NO3)3∙6H2O and the bulky Schiff base ligand, N-naphthalidene-2-amino-5-chlorobenzoic acid (nacbH2), in the presence of the organic base NEt3 has led to crystallization and structural, spectroscopic and magnetic characterization of a new heptanuclear [Dy7(OH)6(OMe)2(NO3)1.5(nacb)2(nacbH)6(MeOH)(H2O)2](NO3)1.5 (1) compound in ~40% yield. Complex 1 has a unique hourglass-like metal topology, among all previously reported {Dy7} clusters, comprising two distorted {Dy4(μ3-OH)3(μ3-OMe)}8+ cubanes that share a common metal vertex (Dy2). Peripheral ligation about the metal core is provided by the carboxylate groups of four η1:η1:η1:μ single-deprotonated nacbH− and two η1:η1:η2:η1:μ3 fully-deprotonated nacb2− ligands. Complex 1 is the first structurally characterized 4f-metal complex bearing the chelating/bridging ligand nacbH2 at any protonation level. Magnetic susceptibility studies revealed that 1 exhibits slow relaxation of magnetization at a zero external dc field, albeit with a small energy barrier of ~5 K for the magnetization reversal, most likely due to the very fast quantum-tunneling process. The combined results are a promising start to further explore the reactivity of nacbH2 upon all lanthanide ions and the systematic use of this chelate ligand as a route to new 4f-metal cluster compounds with beautiful structures and interesting magnetic dynamics.

Two novel analogous Dy 6 complexes were synthesized in low-temperature reactions and characterized via X-ray crystallographic and magnetic measurements. Structural analysis revealed the resulting complexes form a new topological motif for hexanuclear dysprosium clusters. Magnetic studies indicated the two complexes are both ferromagnetic interactions and exhibit magnetization relaxation behavior. [ABSTRACT FROM AUTHOR]

Two Dy III complexes with same N 6 O 3 donor atoms but different donor atom arrangements ‘ fac ’-[Dy III (HL DL-ala ) 3 ]·8H 2 O ( 1 ) and ‘ mer ’-[Dy III (HL DL-phe ) 3 ]·7H 2 O ( 2 ) were synthesized, where H 2 L DL-ala and H 2 L DL-phe are tridentate NNO ligands of N -[(imidazol-4-yl)methylidene]- dl -alanine and N -[(imidazol-4-yl)methylidene]- dl -phenylalanine, respectively. Each Dy III ion is coordinated by three mono-deprotonated mono-negative NNO tridentate ligands to form a nona-coordination geometry of a tricapped trigonal prism (TTP). 1 consists of enantiomers ‘ fac ’-[Dy III (HL D-ala ) 3 ] and ‘ fac ’-[Dy III (HL L-ala ) 3 ], while 2 consists of ‘ mer ’-[Dy III (HL D-phe ) 2 (HL L-phe )] and ‘ mer ’-[Dy III (HL D-phe )(HL L-phe ) 2 ]. The temperature dependence of the magnetic susceptibilities and field-dependence of the magnetization of two complexes showed the different magnetic profiles and the Stark splitting of the ground state 6 H 15/2 due to the crystal field effect on Dy III ion (4f 9 , J = 15/2, S = 5/2, L = 5, g J = 4/3, 6 H 15/2 ). Luminescence spectra were observed and the fine structures assigned to the 4 F 9/2 → 6 H 15/2 transitions are partially observed. 1 and 2 showed an out-of-phase signal with frequency-dependence in alternating current (ac) susceptibility under a dc bias field of 1000 Oe, indicative of field induced single ion magnet (SIM). The ac magnetic susceptibilities under 1000 Oe dc field of 2 showed the maximum peaks at the higher temperature than those of 1 , indicating that the energy barrier of 2 is larger than that of 1 . [ABSTRACT FROM AUTHOR]

Purpose The water molecule exchange rates in a series of DyDOTA-(amide)X chelates were fine-tuned to maximize the effects of T2-exchange line broadening and improve T2 contrast. Methods Four DyDOTA-(amide)X chelates having a variable number of glycinate side-arms were prepared and characterized as T2-exchange agents. The nonexchanging DyTETA chelate was also used to measure the bulk water T2 reduction due solely to T2*. The total transverse relaxivity (r2tot) at 22, 37, and 52°C for each chelate was measured in vitro at 9.4 Tesla (400 MHz) by fitting plots of total T2−1 versus concentration. The water molecule exchange rates for each complex were measured by fitting 17O line-width versus temperature data taken at 9.4 Tesla (54.3 MHz). Results The measured transverse relaxivities due to water molecule exchange (r2ex) and bound water lifetimes (τM) were in excellent agreement with Swift-Connick theory, with DyDOTA-(gly)3 giving the largest r2ex = 11.8 s−1 mM−1 at 37°C. Conclusion By fine-tuning the water molecule exchange rate at 37°C, the transverse relaxivity has been increased by 2 to 30 times compared with previously studied Dy3+-based chelates. Polymerization or dendrimerization of the optimal chelate could yield a highly sensitive, molecule-sized T2 contrast agent for improved molecular imaging applications. Magn Reson Med 71:1179-1185, 2014. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Three new polynuclear dysprosium complexes have been synthesized and characterized via X-ray crystallographic and magnetic measurements. The crystallographic data revealed tri-, octa- and deca-nuclear clusters of formulae [DyIII 3(OH)(teaH2)3(paa)3](Cl)2·MeCN·4H2O (1), [DyIII 8(OH)6(teaH)6(teaH2)2(teaH3)2](O3SCF3)4·0.5MeOH·2H2O (2) and [DyIII 10O2(OH)6(o-van)6(ISO)13(H2O)2](NO3) (3) using the bridging ligands triethanolamine (teaH3), N-(2-pyridyl)-acetoacetamide (paaH), o-vanillin (o-van) and isonicotinic acid (ISO). Compound 1 displays a triangular metallic core, while compound 2 reveals three fused butterfly motifs. Compound 3 displays two trigonal-prismatic units, which are bridged via a single isonicotinate ligand. Variable temperature dc magnetic susceptibility measurements reveal an overall decrease in the χ M T (χ M =molar magnetic susceptibility) product upon lowering the temperature for 1, 2 and 3, with ac magnetic measurements for 2 and 3 displaying peak ‘tails’ in the out-of-phase susceptibilities (χ M″) below 8K, indicating single molecule magnet behavior. [ABSTRACT FROM AUTHOR]

The adsorption behavior and mechanism of D113 resin for Dy(III) was investigated by using the method of resin adsorption. Experimental results show that the optimum medium pH of adsorption of D113 resin for Dy3+ is pH=6.00 in the HAc-NaAc medium. The static adsorption capacity of D113 resin for Dy3+ is 292.7 mg·g−1. The optimum eluant is 0.5 mol·L−1 HCl. The adsorption rate constant is k 298=6.8×10−6s−1. The apparent activation energy of D113 resin for Dy(III) is 14.79 kJ·mol−1. The adsorption behavior of D113 resin for Dy(III) obeys the Freundlich isotherm. The adsorption parameters of thermodynamic are Δ H=14.48 kJ·mol−1, Δ S=54.69 J·mol−1·K−1, Δ G=−1.82 kJ·mol−1.The adsorption mechanism of D113 resin for Dy3+ was confirmed by chemical analysis and IR spectra. [ABSTRACT FROM AUTHOR]

Abstract: Dysprosium(III)-imprinted thenoyltrifluoroacetone (TTA) modified silica gel sorbent was synthesized by surface imprinting technique and was employed as a selective solid-phase extraction material for flow injection solid-phase extraction on-line coupled with inductively coupled plasma-atomic emission spectrometry (ICP-AES) determination of Dy(III). The largest selectivity coefficient for Dy(III) in the presence of competitive ions such as La(III), Nd(III) and Gd(III) was above 350. The static adsorption capacity and selectivity coefficient of the imprinted sorbent are higher than those of the non-imprinted sorbent and the imprinted TTA modified silica gel sorbent offered a fast kinetics for the adsorption and desorption of Dy(III). With a sample loading flow rate of 2.5mLmin−1 for 48s preconcentration and elution flow rate of 1.5mLmin−1 for 8s elution, an enrichment factor of 10 and the sample frequency of 40sampleh−1 were obtained. Detection limits (3σ) based on three times standard deviations of the blanks by eight replicates was 0.2ngmL−1 and the precisions (R.S.D.s) was 1.5% (n =8, c =40ngmL−1). To validate the proposed method, two certified reference materials of GBW07401 soil and GBW07301a sediment were analyzed and the determined values were in a good agreement with the certified values. The method is rapid, selective, sensitive and applicable to the determination of trace Dy(III) in environmental samples with complicated matrix. [Copyright &y& Elsevier]

A novel dysprosium(III) complex of N-(2-propionic acid)salicyloylhydrazone (H3L) and 2,2-dipyridyl (dipy) was prepared and characterized. The crystal structure of [Dy(H2L)(HL)(H2O)3] · 0.5dipy · 2H2O was determined by single-crystal X-ray diffraction methods. In the structure, Dy(III) is 9-coordinated by carboxyl O, acyl O atoms and azomethine N atoms of two ligands (H2L and HL forms) and O atoms from three water molecules. H2L and HL act as tridentate ligands, which form two stable five-numbered rings in the keto form, as indicated by the crystal structure and IR data. The coordination polyhedron around Dy(III) can be described as a monocapped square antiprism. A free 2,2-dipyridyl molecule and two water molecules are connected to coordinated water and ligands by hydrogen bonds to form a three-dimensional structural motif. The complex is highly fluorescent. [ABSTRACT FROM AUTHOR]

Abstract: Ion-selective electrode (ISE) was designed by dispersing the dysprosium(III) IIP particles in 2-nitrophenyloctyl ether plasticizer and then embedded in polyvinyl chloride matrix. The ISE shows a Nernstian response for dysprosium(III) over a wide concentration range (8.0×10−6 to 1.0×10−1 M) with a slope of 21.7mV per decade. The limit of detection was 2×10−6 M. This sensor has a very fast response time (∼10s) and offers high selectivity compared to conventional chemical sensors towards dysprosium(III) with respect to several alkali, alkaline earth and transition metal ions as the selectivity is 10–100-fold better. The sensor was used for determination of dysprosium(III) ions by potentiometric (EDTA) titration and has been successfully demonstrated for the determination of fluoride in mouth wash solution. [Copyright &y& Elsevier]

The complex [Dy(BAA)2(phen)NO3]2 (HBAA?=?phenylacetic acid, phen?=?1,10-phenanthroline) was synthesized under hydrothermal conditions and characterized as by elemental analyses, IR, UV, fluorescence excitation and emission spectroscopy. A single-crystal X-rays structure determination diffraction indicates that the complex is dimeric and Dy has a coordination number of nine. The coordination polyhedron can be described as a distorted, monocapped, square antiprism. Pairs of adjacent metal atoms are bridged by four BAA groups in two coordination modes. The complex is triclinic system, space group P , with a ?=?8.953(6), b ?=?13.312(9), c ?=?13.408(9)?Å, a?=?60.608(7), ß?=?89.674(9), ??=?72.165(9)°, V ?=?1305.0(15)?Å 3 , D c?=?1.718?mg?m -3 , Z ?=?1, F (000)?=?666, R 1?=?0.0424. [ABSTRACT FROM AUTHOR]

Steric structures of dysprosium(III) aminobenzoate complexes with the 1∶1 and 1∶2 molar ratio in aqueous solutions were determined on the basis of pH-metric and paramagnetic birefringence data. An increase in conjugation observed for the series of the acids, viz., benzoic, meta-, ortho-, and para-aminobenzoic acids, results in the increased stability of the complexes with the 1∶1 and 1∶2 composition. In the case of para-aminobenzoic acid, the polyhedra [DyL(HO)] and [DyL(HO)] are cubes with the ligands coordinated to one and two edges, respectively. In the case of meta-aminobenzoic acid, the polyhedra [DyL(HO)] and [DyL(HO)] are a dodecahedron with the ligand coordinated to one edge and a square anti-prism with the ligands coordinated to two edges, respectively. In the case of ortho-aminobenzoic acid, both the 1∶1 and 1∶2 complexes have structures that are intermediate between the structures of meta- and para-aminobenzoic acids. [ABSTRACT FROM AUTHOR]

• Lutetium (III), 1 and dysprosium (III), 2 coordination polymers were synthesized. • Characterized by CHN analysis, IR spectroscopy, TGA-DSC and X-ray crystallography. • 3D MOF encapsulating elongated channels propagating in the [100] direction. • Magnetic susceptibility measurement shows compound 2 obeys the Curie Weiss law. Lutetium(III) and dysprosium(III) coordination polymers containing the 2,5-dihydroxybenzene1,4-dicarboxylate (Dhbdc, C 8 H 4 O 6 2−) ligand, [Lu(Dhbdc) 1.5 (H 2 O) 4 ] n · n C 2 H 6 O· n H 2 O (1) and [Dy(Dhbdc) 1.5 (H 2 O) 3.58 (C 2 H 6 O) 0.42 ] n · n C 2 H 6 O·0.42 n H 2 O (2) have been prepared from a mixed solvent system and characterized by elemental analysis, infrared spectroscopy, TGA–DSC and X-ray crystallography. The crystal structural analysis reveals that 1 and 2 are almost isostructural, differing slightly in the coordination of the solvent molecules to the respective metal ions. The coordination polyhedra around the metal atoms in 1 and 2 can be described as distorted LnO 8 triangular dodecahedra. The structures of the complexes are extended into three-dimensional metal-organic frameworks encapsulating elongated channels propagating in the [1 0 0] direction. In both compounds, O H...O hydrogen bonds arising from the coordinated water and solvent molecules help to consolidate the structures. Magnetic susceptibility (χ m) measurements were carried out for complex 2 , which was found to obey the Curie Weiss law. Luminescent studies of complex 2 indicate that it displays enhanced ligand-centred fluorescence. [ABSTRACT FROM AUTHOR]

The reaction between Dy(NO3)3∙6H2O and the bulky Schiff base ligand, N-naphthalidene-2-amino-5-chlorobenzoic acid (nacbH2), in the presence of the organic base NEt3 has led to crystallization and structural, spectroscopic and magnetic characterization of a new heptanuclear [Dy7(OH)6(OMe)2(NO3)1.5(nacb)2(nacbH)6(MeOH)(H2O)2](NO3)1.5 (1) compound in ~40% yield. Complex 1 has a unique hourglass-like metal topology, among all previously reported {Dy7} clusters, comprising two distorted {Dy4(μ3-OH)3(μ3-OMe)}8+ cubanes that share a common metal vertex (Dy2). Peripheral ligation about the metal core is provided by the carboxylate groups of four η1:η1:η1:μ single-deprotonated nacbH− and two η1:η1:η2:η1:μ3 fully-deprotonated nacb2− ligands. Complex 1 is the first structurally characterized 4f-metal complex bearing the chelating/bridging ligand nacbH2 at any protonation level. Magnetic susceptibility studies revealed that 1 exhibits slow relaxation of magnetization at a zero external dc field, albeit with a small energy barrier of ~5 K for the magnetization reversal, most likely due to the very fast quantum-tunneling process. The combined results are a promising start to further explore the reactivity of nacbH2 upon all lanthanide ions and the systematic use of this chelate ligand as a route to new 4f-metal cluster compounds with beautiful structures and interesting magnetic dynamics. [ABSTRACT FROM AUTHOR]