Tricapped Trigonal Prism Research Articles

Crystal chemical investigations on TiU8S17 and U36Lu21S93I3 - ordered and disordered multinary uranium sulfides

The crystal chemistry of uranium sulfides is characterized by a large diversity in composition, crystal structures, oxidation states and physical properties. This holds also for TiU8S17 and U36Lu21S93I3, of which large single crystals up to several mm in length were grown by chemical vapor transport using iodine as a transport agent. TiU8S17 crystallizes with the monoclinic CrU8S17 structure type (C2/m, a = 13.3477(2) Å, b = 8.4927(2) Å, c = 10.4836(2) Å, β = 101.207(2)°) featuring distorted octahedra [TiS6] and bicapped trigonal prisms [US8]. Interatomic distances and X-ray photoelectron spectra indicate tetravalent uranium. Disordered U36Lu21S93I3 represents a new structure type (R3¯m, 13.3841(2) Å, 20.6447(2) Å) with an average crystal structure exhibiting square antiprisms [LuS8], bi- and tricapped trigonal prisms [US8] and [US9] and distorted octahedra [IU6]. Lutetium and sulfur atoms are disordered similar to Ce53Fe12S90X3, La53Fe12S90X3 (X = Cl, Br, I) and La52Fe12S90. This might be caused by positional shifts of iodine atoms away from the center of the polyhedron, thus avoiding unusually long U–I distances and severely disrupting the order of neighboring lutetium and sulfur atoms. The results of chemical analyses (ICP-MS, EDX), electron microscopy (TEM) and X-ray photoelectron spectroscopy support the composition and crystal structure of U36Lu21S93I3 and indicate mixed valency of uranium and charge balance according to the crystal chemical formula (U+III)18(U+IV)18(Lu+III)21(S-II)93(I–I)3.

Synthesis, structural characterization, molecular docking analysis and Carbonic Anhydrase IX inhibitory evaluations of novel Cerium(III)-based MOF constructed from 1,10-phenanthroline and fumaric acid.

In this study, a novel Cerium-based MOFs with 1,10-phenanthroline (phen) and fumaric acid (H2fum) has been hydrothermally synthesized as single crystal structurally characterized by X-ray diffraction, IR spectroscopy and ATG measurements. This compound corresponds to the formula: [Ce2(phen)2(fum)3(H2O)2]n(I), it crystallizes in the triclinic system with space group P1¯, with the following parameters: a = 9.062(1) Å, b = 10.0608(5) Å, c = 10.603(1) Å, α = 72.545(6) °, β = 77.57(1) °, γ = 69.959(6) °, V = 859.49(14) Å3, Z = 2.The structure revealed 2D bridged polymeric chains where the adjacent Ce(III) atoms are bridged by fumarate linkers with a mean intermetallic distance of about 9.36 Å. H···O bonds link the 2D sheets leading to a pseudo 3D network, while the stability of the structure is assured by a weak π-π stacking between parallel and opposed phen ligands.The Ce3+ cation is nona-coordinated and it is in a distorted tricapped trigonal prism geometry.Hirshfeld surface analysis was used to investigate the non-covalent intermolecular interactions and the dominant H···O, H···C and H···H contacts were quantified. The thermal properties of the considered coordination polymer (I) are also discussed and disclose that (I) is stable up to 300°C. Besides, this study explores the potential of (I) as an inhibitor of the carbonic anhydrase IX enzyme (CA IX), a critical player in tumor microenvironment regulation. Through molecular docking simulations, we elucidate the binding interactions between (I) and CA IX, the results suggest the efficiency of (I) as a CA IX inhibitor. Moreover, we assessed the drug-likeness properties and ADMET characteristics of (I), providing valuable insights for its potential as a therapeutic agent.

On the Thermal Dimorphy of the Strontium Perrhenate Sr[ReO4]2

AbstractHygroscopic single crystals of a new hexagonal high‐temperature modification of Sr[ReO4]2 were prepared from a melt of Sr[ReO4]2 ⋅ H2O and SrCl2 ⋅ 6 H2O. The structure analysis of the obtained crystals by X‐ray diffraction revealed that the title compound crystallizes in the ThCd[MoO4]3‐type structure with the hexagonal space group P63/m and the lattice parameters a=1023.81(7) pm and c=646.92(4) pm (c/a=0.632) for Z=2 in its quenchable high‐temperature form. Two crystallographically independent Sr2+ cations are coordinated by oxygen atoms forming either octahedra or tricapped trigonal prisms, whereas the Re7+ cations are found in the centers of discrete tetrahedral meta‐perrhenate units [ReO4]−. Temperature‐dependent in‐situ PXRD studies of dry powder samples of Sr[ReO4]2 exhibited its thermal dimorphy with a phase‐transition temperature at 500–550 °C from literature‐known m‐Sr[ReO4]2 into the newly discovered h‐Sr[ReO4]2 (hexagonal).

Synthesis, spectroscopic properties, crystal structure and Hirshfeld surface analysis of Pr(III), Sm(III), Gd(III), Dy(III), and Ho(III) coordination compounds with Schiff base ligand derived from 4-aminoantipyrine

Under reflux condition five new lanthanide coordination compounds, [Pr(L)2(NO3)3(CH3OH)] (1), [Sm(L)2(NO3)3(CH3OH)] (2), [Gd(L)2(NO3)3(CH3OH)] (3), [Dy(L)2(NO3)3(CH3OH)] (4) and [Ho(L)2(NO3)3(CH3OH)] (5), were synthesized in methanol where L is the Schiff base ligand prepared from the reaction of 4-aminoantipyrine and 5-bromosalicylaldehyde. Elemental analysis, FT-IR, UV/Vis and photoluminescence spectroscopic methods and single crystal X-ray analysis were used to investigate the crystal structure and properties of the synthesized compounds. Using X-ray analysis, it was found that all crystals are isomorphous and the Ln ion (Ln = Pr, Sm, Gd, Dy and Ho) in all of the synthesized compounds is nine-coordinated and the geometry around them is slightly distorted tricapped trigonal prism. Six oxygen atoms are coordinated to the central lanthanide atom by three nitrate groups, one oxygen atom from the methanol group and two oxygen atoms of the Schiff base ligand (L) which create the LnO9 coordination environment. Intermolecular interactions and the distribution of these interactions in all of these crystals were calculated by Hirshfeld surface analysis using Crystal Explorer 17.5 software. The emission spectrum of these compounds was recorded and the obtained results showed that the intensity of peaks has differences and the emission spectrum of the complexes changes by changing the lanthanide ions.

Synthesis, Characterization, and Catalytic Performance of a New Heterobimetallic Y/Tb Metal-Organic Framework with High Catalytic Activity.

A three-dimensional heterobimetallic porous structure with the formula {[Y3.5Tb1.5L6(OH)3(H2O)1.5 (DMF)1.5] n ·1.5H2O·DMF} n (L = 3-amino-4-hydroxybenzoate) (Y/Tb-MOF) has been synthesized and characterized by single crystal and powder X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), inductively coupled plasma mass spectrometry (ICP-MS), electrophoretic mobility, and Fourier transform infrared (FTIR) spectroscopy. The structure presents two metal environments: a bioaugmented isosceles wedge (mm2) MO8 and a tricapped trigonal prism (-6m2) MN3O6. These configurations facilitate the creation of channels with a diameter of 10.7 Å, enabling its utilization as an active catalyst where the heterobimetallic nature of the assembly will be explored. This mixed-metal metal-organic framework has been tested in the cycloaddition of epoxides with carbon dioxide as well as in the cyanosilylation and hydroboration reactions of carbonylic substrates. Additionally, a monometallic Tb-MOF analogue has been synthesized for comparative evaluation of their catalytic performances. Both the mixed metal and monometallic variants exhibit outstanding activity in the cyanosilylation and hydroboration of carbonyls and in the synthesis of carbonates under CO2 pressure. However, only the latter exhibits high recyclability.

Cu(II)-Ln(III) (Ln = Gd, Tb and Dy) complexes of an unsymmetrical N2O3 donor ligand: field induced SMM behaviour of Cu(II)-Tb(III) complexes.

Three new hetero-metallic CuII-LnIII complexes [(CuL)Gd(NO3)3(CH3OH)]n (1), [(CuL)Tb(NO3)3(H2O)]·[CuL] (2) and [(CuL)Dy(NO3)3(H2O)]·[CuL] (3) have been synthesized using a mono-nuclear Cu(II) complex, [CuL], of an unsymmetrically di-condensed N2O3 donor Schiff base ligand, N-(3-methoxysalicylidene)-N-(salicylidene)-1,2-ethylenediamine (H2L). Single crystal X-ray crystallography revealed that complex 1 is a nitrate bridged 1D chain of dinuclear Cu(II)-Gd(III) units whereas in 2 and 3, the dinuclear Cu(II)-Ln(III) units are co-crystallized with a [CuL] unit. The Ln(III) centers are nine coordinated with the geometry of a spherical capped square antiprism for Gd and spherical tricapped trigonal prism for Tb and Dy. The geometry of the Cu(II) center is distorted octahedral for complex 1 and distorted square planar for complexes 2 and 3. Temperature-dependent molar magnetic susceptibility measurements in 1-3 revealed the presence of overall ferromagnetic coupling between the Cu(II) and Ln(III) centers. Notably, field induced single-molecule magnet behavior was witnessed in the Tb(III) derivative (2). The ab initio calculations indicated that upon application of an external magnetic field, the tunneling in the ground state of complex 2 gets reduced and thereby field-induced SMM behaviour is observed. Besides, in the case of complex 1, BS-DFT calculations were carried out to gain further insights into the magnetic exchange coupling interactions between the Cu(II) and Gd(III) centers.

Lanthanoid(Ⅲ) complexes containing bipyridinedicarboxylic acid ligand: Synthesis, spectroscopic characterization, thermal analysis, and crystal structures

The present report deals with the synthesis of the two complexes of respective formula {[Ce(bpydcb)(HCOO)(H2O)]·H2O}n (1) and [Eu2(bpydcb)3(H2O)2(DMF)]·3H2O·0.5DMF (2) the structure of both of them elucidated by single-crystal X-ray diffraction and powder X-ray diffraction to demonstrated that complexes 1 and 2 crystallize in a similar space group P21/c as a monoclinic system with high crystal purity. X-ray Single crystal diffraction analysis demonstrates, nine-coordinate environment of Ce (Ⅲ) in the complex 1 and octa-coordinate environment of Eu (Ⅲ) in the complex 2. And discovered the tricapped trigonal prism of cerium complex and the triangular dodecahedron of europium complex. Meanwhile, the complexes were characterized by elemental, infrared, ultraviolet, fluorescence and thermal analysis. Fluorescence testing shows that complex 1 emits ligand fluorescence, while complex 2 emits fluorescence from the ligand to the central ion, emitting characteristic fluorescence of europium ion, both complexes can emit strong fluorescence. The thermogravimetric analysis results show that the thermal stability of complex 1 is better than that of complex 2, and its organic framework only begins to collapse after 375 ℃.

Determination of Ground State Structures of Snx - (x=21-35) Clusters.

In this work, an unbiased global search with a homemade genetic algorithm was performed to investigate the structural evolution and electronic properties of Snx - (x=21-35) clusters with density functional theory (DFT) calculations. All the ground-state structures for all these Snx - (x=21-35) clusters have been confirmed by the comparison of the experimental and simulated photoelectron spectra (PESs). It has been revealed that all Snx - (x=21-35) clusters are tricapped trigonal prism (TTP)-based structures consisting of two (for sizes x=21-28) or three (for x=29-35) TTP units, with the remaining atoms adsorbed on the surface or inserted between TTP units. The gradually decreasing HOMO-LUMO gaps indicate that these clusters are undergoing semiconductor-to-metal transformation. The average binding energies show that the structural stabilities of Snx - clusters are not as good as that of silicon and germanium clusters. It found that sizes x=23, 25, 29, 33 show high relative stability.

Unraveling influence of entropy on thermal stability and glass-forming ability of (Fe, Co)–(Ta)–B amorphous alloys: Insights from local atomic structure simulated by ab initio molecular dynamics

The thermal stability, glass-forming ability (GFA), and local atomic structure of (Fe, Co)–(Ta)–B amorphous alloys with different entropy values were investigated by experiments and ab initio molecular dynamics simulations, and the effects of entropy were elaborated from the perspective of the local atomic structure. The experimental results show that crystallization temperature, activation energy for crystallization, and undercooling degree all rise with the increase of configurational entropy (ΔSconf) of the alloys, whereas the critical thickness for amorphous samples shows a weak correlation with the ΔSconf. The simulations indicate that the short-range orders of the amorphous alloys are all dominated by B-centered tri-capped trigonal prisms (TTPs) and bi-capped square Archimedean antiprisms, and Fe-/Co-centered deformed body-centered cubic structures (BCCs) and icosahedral-like structures (ICOs) mainly with covalent-like B–Fe/Co and metallic Fe/Co–Fe/Co bonds. The increase in the ΔSconf results in shortened bond lengths and strengthened interactions between the main atomic pairs and sluggish diffusion of the atoms, thereby leading to enhanced thermal stability of both the amorphous phases and alloy melts. The GFA of the alloys shows a strong correlation with the characteristics of the short-range orders but not the entropy. The alloy containing the lowest fractions of the TTPs and BCCs but considerable ICOs possesses the best GFA.

Structures of Th4+ aqueous solutions: insights from AIMD and metadynamics simulations.

Solution chemistry of actinide ions is critical to understanding the solvation behaviors and hydrolysis process. Using tetravalent thorium ion Th4+ as a representative example, we investigate the local structures and dynamic behaviors of hydrated Th4+ ions by ab initio molecular dynamics (AIMD) simulations using the recently developed norm-conserving pseudopotentials and basis sets optimized for actinides (J.-B. Lu et al., J. Chem. Theory Comput. 2021, 17, 3360-3371). AIMD simulations reveal two distinct solvation shells, with the first shell comprising 9 water molecules at approximately rTh-O = 2.50 Å and exhibiting a tricapped trigonal prism geometry. These conclusions are confirmed through metadynamics simulations and further structural analysis. AIMD simulations also show the slight effect of temperature and counterions on the structure of the solution. The structured solvation shells of the highly charged Th4+ ion with the specific geometry, distinct from the structure of liquid water, lead to corresponding structural changes in the hydrogen bond network in water. Additionally, beyond the solvent-shared ion pair (SIP) state observed in the unbiased AIMD simulations, the metadynamics simulations reconstruct a two-dimensional free energy surface that clearly indicates the potential stability of the contact ion pair (CIP) state in the system with Cl- as a counterion. The findings in this work provide insights into the solution chemistry of actinides and serve as a reference for studying other actinide solution systems.

Actinide‐Pnictide Chemistry: A Uranium Primary Alkyl Stibinide and a Diuranium Hexaantimonide‐Tetralithium Zintl Cluster

AbstractStructurally characterised U−Sb bonds are rare. Here, the synthesis and characterisation of [U(TrenDMBS){Sb(H)C(H)(SiMe3)2}] (5, TrenDMBS=N(CH2CH2NSiMe2But)3) and [{U(TrenTIPS)}2{Sb3(μ6‐Li)(μ‐Li[THF]2)3Sb3}] (6, TrenTIPS=N(CH2CH2NSiPri3)3) are reported. Complex 5 is an unprecedented primary stibinide actinide complex and 6 can be formulated as containing a unique triple decker 20 skeletal‐electron distorted closo tricapped Zintl cluster (Sb3Li4Sb3)2− that is analogous to the D3h closo tricapped trigonal prism form of [Ge9]2−. Quantum chemical calculations emphasise polar U−Sb bonding in 5 and 6, and that viewing (Sb3Li4Sb3)2− as a single unit rather than two distinct but contiguous (Sb3)3− units, themselves unprecedented in molecular actinide chemistry, is valid due to the presence of three weak (Sb3)⋯(Sb3) (3, −1)‐bond critical points. Complexes 5 and 6 highlight the challenges of preparing polar U−Sb bonds and the underlying tendency for unpredictable cluster formation with Sb.

Fabrication of Ni–Mo–Nb metallic glass/micro-nano lattice composite for nonenzymatic glucose sensing

The rising global diabetic population has ignited significant interest in enzyme-free electrochemical glucose sensors. However, their widespread usage has been severely impeded by the lack of sensing probes with both high sensitivity and stability. In this work, we present a novel approach for conformally depositing a Ni–Mo–Nb metallic-glass film onto a three-dimensional printed polymer skeleton for glucose detection. The printing template is designed based on a six-membered tricapped trigonal prism (6M-TTP) structure, which is derived from a medium-range order structure motif observed in amorphous alloys. The fabricated composite combines the high electrochemical activity of Ni–Mo–Nb amorphous alloy with the stability afforded by the micro-nano lattice structure, resulting in a high sensitivity (482 ​μA mM−1cm−2), a wide linear range (0–1 ​mM and 1–5 ​mM), a low detection limit (2.94 ​μM), and good long-term stability and selectivity in alkaline solution. Our work has proposed a new avenue to fabricate complex micro-nano electrodes, potentially offering significant versatility and great promise for widespread applications in the field of electrochemistry.

Cementite-type Y3Ru

Abstract Single crystals of Y3Ru were obtained as a side product during phase analytical studies of yttrium-rich compounds in the system Y–Ru–Zn. The structure of Y3Ru was refined from single-crystal X-ray diffractometer data: Fe3C type, Pnma, a = 732.51(7), b = 925.61(8), c = 633.66(10) pm, wR = 0.0639, 811 F 2 values, 23 variables. The ruthenium atoms have coordination number 9 in form of a strongly distorted tricapped trigonal yttrium prism with Ru–Y distances ranging from 275–391 pm. The second substructure concerns empty Y6 octahedra (d(Y–Y) = 344–396 pm). Electronic structure calculations show a net charge transfer from yttrium to ruthenium and underpin the essentially covalent Y–Ru bonding. A phase-pure sample of Y3Ru was synthesized from the elements by arc-melting. Temperature-dependent magnetic susceptibility studies of this sample reveal Pauli paramagnetism (3.6(1) × 10−5 emu mol−1 at T = 300 K).

A family of mono-nuclear lanthanide-radical complexes: Synthesis, structures, magnetic and fluorescent properties

Two new rare earth complexes based on TEMPO derivative namely [Ln(hfac)3(H2O)hmb-TEMPO] (Ln = Gd 1, Tb 2; hmb-TEMPO = 4-((2-hydroxy-3-methoxybenzylidene) amino)-2,2,6,6-tetramethyl; hfac = hexafluoroacety lacetonate) were successfully synthesized through reacting hmb-TEMPO radical and Ln(hfac)3. Single-crystal X-ray diffraction reveals that 1 and 2 are isostructural complexes in which the LnIII ion is surrounded nine oxygen atoms and displayed distorted tricapped trigonal prism geometry. Magnetic studies show that antiferromagnetic interactions dominate in complex 1. Nonzero out-of-phase signals were observed for complex 2, indicating single-molecule magnet behavior. The low-temperature photoluminescence spectrum of complex 2 were investigated and discussed in detail.

Anionic Templates Drive Conversion between a ZnII9L6 Tricapped Trigonal Prism and ZnII6L4 Pseudo-Octahedra.

This work introduces the use of 8-aminoquinoline subcomponents to generate complex three-dimensional structures. Together with a tris(formylpyridine), 8-aminoquinoline condensed around ZnII templates to produce a tris(tridentate) ligand. This ligand is incorporated into either a tricapped trigonal prismatic ZnII9L6 structure or a pair of pseudo-octahedral ZnII6L4 diastereomers, with S4 and D2 symmetries. Introduction of a methyl group onto the aminoquinoline modulated the coordination sphere of ZnII, which favored the ZnII9L6 structure and disfavored the ZnII6L4 assembly. The tricapped trigonal prismatic ZnII9L6 architecture converted into a single ZnII6L4 cage diastereomer following the addition of a dianionic 4,4'-dinitrostilbene-2,2'-disulfonate guest. Four of these guests clustered tightly at the four windows of the ZnII6L4 cage, held in place through electrostatic interactions and hydrogen bonding, stabilize a single diastereomeric configuration with S4 symmetry.

Crystal structures of two SmIII complexes with dipicolinate [DPA]2- ligands: comparison of luminescent properties of products obtained at different pH values.

The formation of the two title compounds, Na3[Sm(DPA)3]·14H2O tris-odium tris-(pyridine-2,6-di-carboxyl-ato-κ3 O 2,N,O 6)samarate(III) tetra-deca-hydrate, Na3[Sm(C7H3NO4)3]·14H2O, and catena-poly[[[di-aqua-(6-carb-oxy-pyridine-2-carb-oxyl-ato-κ3 O 2,N,O 6)samarium(III)]-μ-pyridine-2,6-di-carboxyl-ato-κ4 O 2,N,O 6:O 2] tetra-hydrate], {[Sm(C7H3NO4)(C7H4NO4)(H2O)2]·4H2O}n, depends on the pH value adjusted with NaOH solution. In both crystal structures, the coordination spheres of the SmIII cations were found to be best described by a tricapped trigonal prism (TTP), with a more regular O6N3 donor set for Na3[Sm(DPA)3]·14H2O than that of O7N2 for [Sm(DPA)(HDPA)(H2O)2]·4H2O. The supra-molecular features of both crystal structures are dominated by O-H⋯O hydrogen bonds between water mol-ecules and the O atoms of the dipicolinato ligands. Samples were made from solutions at pH = 2, pH = 5, pH = 7, and pH = 10, and the crystals present in each sample were ground to a powder. The powder samples were analyzed with powder X-ray diffraction and luminescence spectroscopy. The splitting of the bands in the luminescence spectra recorded on powders at 77 K was observed to vary with the pH.

Anion-induced differential assembly and structural transformation of supramolecular coordination cages

The intimate host-anion interactions will regulate thermodynamics and kinetics in the self-assembly of cationic cages mimicking biological counterparts. Herein, we report construction and transformation of three Pd(II)-based metal-organic cages (MOCs) depending on different anions. Stoichiometric conversions of the lantern-shaped MOC-34 into either octahedral MOC-35 or tricapped trigonal prism MOC-36 are induced by BF4‒ or NO3‒, respectively. MOC-36 is kinetically favored and can undergo quantitative conversion to the thermodynamically preferred MOC-35 upon heating, accelerated by excess BF4‒ to motivate dissociative dynamics of Pd-vertices and lower activation barrier of cage transformation. The guest encapsulation behaviors of MOC-35 and MOC-36 have also been tested. These results manifest a significance of host-anion dynamics beyond complementary anion template, shedding light on the understanding of intricate anion recognition in nature.

KNO3⋅3H2SeO3 and NaHSeO3⋅3H2SeO3: Two non-centrosymmetric co-crystals

A new compound KNO3⋅3H2SeO3 was synthesized via reaction of KNO3 and H2SeO3 in an acidic aqueous solution. Its crystal structure (P21, a = 10.2709 (8) Å, b = 6.2840 (3) Å, c = 10.3886 (8) Å, β = 118.83 (1)°, R1 = 0.036) can be described as a monoclinically distorted hydrogen-bonded hexagonal net of KO9 tricapped trigonal prisms linked by H2SeO3 molecules. The nitrate anions behave as hydrogen bond acceptors filling the channels in the [K(H2SeO3)3]+ net. The structure is totally different from that of the chemically related NaHSeO3⋅3H2SeO3 compound, for which a new structural solution was obtained (Pc, a = 5.7803 (3) Å, b = 4.9390 (2) Å, c = 21.283 (1) Å, β = 111.836 (6)°, R1 = 0.028). Yet, there are some common features in the mode of KO9 and NaO6 polyhedra linkage by the HSeO3− and H2SeO3 species in two studied compounds. The SHG signal from KNO3⋅3H2SeO3 was registered using the Kurtz – Perry technique. A moderate SHG signal of 5–6 SiO2 units was observed. Relationships to other salt-selenious acid molecular co-crystals and hydrogen selenites are discussed.

Peripheral site modification in a family of dinuclear [Dy2(hynad)2-6(NO3)0-6(sol)0-2]0/2- single-molecule magnets bearing a {Dy2(μ-OR)2}4+ diamond-shaped core and exhibiting dissimilar magnetic dynamics.

The first use of the organic chelate N-hydroxy-1,8-naphthalimide (hynadH) in DyIII chemistry has unveiled access to a synthetic 'playground' composed of four new dinuclear complexes, all of which possess the same planar {Dy2(μ-OR)2}4+ diamond-shaped core, resulting from the bridging and chelating capacity of the hynad- groups. The structural stability of the central {Dy2} core has allowed for the modulation of the peripheral coordination sites of the metal ions, and specifically the NO3-/hynad- ratio of capping groups, thus affording the compounds [Dy2(hynad)2(NO3)4(DMF)2] (1), (Me4N)2[Dy2(hynad)2(NO3)6] (2), [Dy2(hynad)4(NO3)2(H2O)2] (3), and [Dy2(hynad)6(H2O)2] (4). Because of the chemical and structural modifications in the series 1-4, the DyIII coordination polyhedra are also dissimilar, comprising the muffin (1 and 3), tetradecahedral (2), and spherical tricapped trigonal prismatic (4) geometries. Complexes 1, 2, and 4 exhibit a ferromagnetic response at low temperatures, while 3 is antiferromagnetically coupled. All compounds exhibit out-of-phase (χ''M) ac signals as a function of ac frequency and temperature, thus behaving as single-molecule magnets (SMMs), in the absence or presence of applied dc fields. Interestingly, the hynad--rich and nitrato-free complex 4, demonstrates the largest energy barrier (Ueff = 69.62(1) K) for the magnetization reversal which is attributed to the presence of the two axial triangular faces of the spherical tricapped trigonal prism by the negatively charged O-atoms of the hynad- ligands.

Lanthanide(III) Complexes with Thiodiacetato Ligand: Chemical Speciation, Synthesis, Crystal Structure, and Solid-State Luminescence

The synthesis, crystal structures, and luminescence of two lanthanide polynuclear complexes with the general formula [Ln2(tda)3(H2O)5]·3H2O (Ln = Sm, Eu; tda = thiodiacetato anion) are reported. The compounds were obtained by direct reaction of H2tda and lanthanide(III) chloride in an aqueous solution. The choice of the conditions of synthesis was based on speciation studies. The structure of the polymeric complexes contains Ln(III) ions in a tricapped trigonal prism geometry. The versatility of this ligand provides different coordination modes and provokes the formation of thick 2D sheets. Direct excitation of the Ln(III) ions gives place to the characteristic intra-configuration sharp luminescence emission of both complexes in the solid state.