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Heteroleptic homo dinuclear complexes [Sm(fod)3(μ-bpp)Sm(fod)3] and [Eu(fod)3(μ-bpp)Eu(fod)3] and their diamagnetic analogue [Lu(fod)3(μ-bpp)Lu(fod)3] (fod is the anion of 6,6,7,7,8,8,8- heptafluoro-2,2-dimethyl-3,5-octanedione (Hfod) and bpp is 2,3-bis(2-pyridyl)pyrazine) are synthesized and thoroughly characterized. The lanthanum gave a 1:1 adduct of La(fod)3 and bpp with the molecular formula of [La(fod)3bpp]. The 1H NMR and 1H-1H COSY spectra of the complexes were used to assign the proton resonances. In the case of paramagnetic Sm3+ and Eu3+ complexes, the methine (of the fod moiety) and the bpp resonances are shifted in the opposite direction and the paramagnetic shifts are dipolar in nature, which decrease with increasing distance of the proton from the metal ion. The single-crystal X-ray analyses reveal that the complexes (Sm3+ and Eu3+) are dinuclear and crystallize in the triclinic P1 space group. Each metal in a given complex is eight coordinate by coordinating with six oxygen atoms of three fod moieties and two nitrogen atoms of the bpp. Of the two metal centers, in a given complex, one has a distorted square antiprism arrangement and the other acquires a distorted dodecahedron geometry. The Sparkle RM1 and PM7 optimized structures of the complexes are also presented and compared with the crystal structure. Theoretically observed bond distances are in excellent agreement with the experimental values, and the RMS deviations for the optimized structures are 2.878, 2.217, 2.564, and 2.675 Å. The photophysical properties of Sm3+ and Eu3+ complexes are investigated in different solvents, solid, and PMMA-doped thin hybrid films. The spectroscopic parameters (the Judd–Ofelt intensity parameters, radiative parameters, and intrinsic quantum yield) of each Eu3+ sites are calculated using the overlap polyhedra method. The theoretically obtained parameters are close to the experimental results. The lifetime of the excited state is 38.74 μs for Sm3+ and 713.62 μs for the Eu3+ complex in the solid state.

We report the synthesis, single-crystal structure, solid-state ultraviolet-visible-near-infrared spectroscopy, and theoretical calculations on the first trivalent plutonium crown ether inclusion complex, [(H3O)(18-crown-6)][Pu(H2O)4(18-crown-6)](ClO4)4·2(H2O) (denoted as PuIII-18C6). Single-crystal X-ray diffraction reveals that PuIII-18C6 crystallizes in the orthorhombic space group of Pccn, which is assembled by independent ionic pairs including [Pu(H2O)4(18-crown-6)]3+, [(H3O)(18-crown-6)]+, and perchlorate anions. The plutonium atom is fully encapsulated within the cavity of the 18-crown-6, generating a distorted bicapped square antiprism geometry. The theoretical evaluation confirms that weak Pu-O dative bond is involved between PuIII ions with 18-crown-6. This work may deepen the understanding of the host-guest interactions between trivalent transuranic and macrocyclic ligands.

Since [Sn8 ]6- was discovered from the solid-state phase in 2000, its solution chemistry has been elusive due to the high charges and chemical activity. Herein, we report the synthesis and characterization of an inverse sandwich-type cluster dimer {[K2 ZnSn8 (ZnMes)]2 }4- (1 a), in which the highly charged [Sn8 ]6- is captured by mixed-valence ZnI /ZnII to form the dimer {closo-[Zn2 Sn8 ]}2 moieties bridged by a Zn-Zn bond. Such Zn-Sn cluster not only exhibits a novel example of mixed-valence ZnI /ZnII for stabilizing highly active anion species, but also indicates the [Sn8 ]6- cluster can act as a novel bridging ligand, like arene, with a η4 :η4 -fashion. Theoretical calculations indicate that a significant delocalization of electrons over Zn atoms plays a vital role in the stabilization of the [Sn8 ]6- species. The AdNDP and magnetic response analyses clearly showed the presence of local σ-aromaticity in three cluster fragments: two ZnSn4 caps and Sn8 square antiprism.

New ytterbium (III) compounds with β-diketones (2,7-dimethyl-octene-1-dione-3,5 and 2,6-dimethylheptene-1-dione-3,5) and their derivatives with phenanthroline have been synthesized. The composition and chemical structure of the obtained complexes have been determined by several Phy­sico-chemical investigations. It has been shown, that the Yb (III) ion coordinates three ligand molecules and the coordination sphere of the complexes is supplemented by two mole­cules of water or a molecule of phenanthroline. It has been shown that the СN of the ytterbium ion is 8, the coordination polyhedron is a square antiprism, and the complex is characte­rized by no cubic symmetry. All synthesized compounds exhibit intense IR luminescence. The significant increase in the relative emission intensity of mixed ligand complexes is due to the additional antenna effect of the phenanthroline molecule.

A novel erbium material with a fascinated mercury bromide cluster (Hg11Br34)12– anion, i.e., {[Er2(H2O)4(HIA)6]2n}(nHg11Br34)(nHgBr2)·4nH2O (denoted as 1 and HIA indicates the isonicotinic acid molecule), was successfully synthesized from a solvothermal reactor. Its single crystal structure was determined by single-crystal and powder X-ray diffractions. The Er3+ ions have a distorted square antiprism motif, and they are connected by isonicotinic acid molecules to yield a one-dimensional (1-D) chain. The Hg2+ ions show two or four coordination motifs. This compound contains an unprecedented mercury bromide cluster (Hg11Br34)12– anion. This compound shows upconversion green photoluminescence emission with a CIE (Commission Internationale de I'Eclairage) chromaticity coordinates at (0.1749, 0.4351). It has a wide band gap of 3.24 eV. A novel erbium material with a fascinated mercury bromide cluster (Hg11Br34)12– anion was reported. The Er3+ ions have a distorted square antiprism motif and the compound features a 1-D chain-like structure. The Hg2+ ions show two or four coordination motifs. It features upconversion green emission with CIE coordinates 0.1749 and 0.4351. It has a wide band gap of 3.24 eV.

Three nickel(II), manganese(II) and cadmium(II) complexes, [NiL2] (I), [MnL2] (II) and [Cd(HL)2(NO3)]·NO3 (III), derived from 4-bromo-N'-(1-(pyridin-2-yl)ethylidene)benzohydrazide (HL) were prepared and characterized by IR and UV spectra. Structures of the complexes were further confirmed by single crystal X-ray diffraction techniques (CIF files CCDC nos. 1874307 (I), 1874308 (II), and 1874309 (III)). The Ni atom in complex I and the Mn atom in complex II are in octahedral coordination. The Cd atom in complex III is in square antiprism coordination. The nickel complex is effective on the inhibition of Jack bean urease.

The mononuclear complexes [Dy(3Br,5Cl-H3L1,1,4)(D)]·solvate (D = H2O, solvate = 0.25MeOH, 1W·0.25MeOH; D = Py without solvate, 1Py), and [Dy(3NO2,5Br-H3L1,1,4)(H2O)] (2W) were isolated. The crystal structures of 1W·0.25MeOH, 1Py and 2W·2CH3C6H5 show that the DyIII ion is octacoordinated, in N4O4 or N5O3 environments, with distorted geometries, between square antiprism, biaugmented trigonal prism and triangular dodecahedral. A similar environment for the metal ion is shown in the chiral crystals of the diamagnetic yttrium analogue [Y(3Br,5Cl-H3L1,1,4)(MeOH)] (3M), which were spontaneously resolved. Magnetic analyses of the three dysprosium complexes, and their diluted analogous 1W@Y, 1Py@Y and 2W@Y, reveal that none of them seem to relax through an Orbach mechanism at Hdc = 0. However, the three complexes show Orbach relaxation under Hdc = 1000 Oe, and 1Py is the in-field SIM with the highest energy barrier among these complexes, with a Ueff value of 358 K. Analysis of ac magnetic data shows that the electron-withdrawing substituents on the phenol rings of the aminophenol ligands, as well as the auxiliary oxygen donors from water ligands, reduce the energy barriers of the complexes, which is attributed to a charge reduction in the coordinating atoms of the aminophenol donor. Ab initio calculations support the experimental results.

A new series of 3D lanthanide (Ln) frameworks has been synthesized with the general formula [{Ln(L)(H2O)}·H2O]n (where Ln = La(1), Tb(2) and Dy(3); L = (HO)OC6H2(CH2COO)2; H3L = 2,5-dihydroxy-1,4-benzenediacetic acid = DHBDA). All the crystals were analyzed by single crystal X-ray diffraction. The Ln ions are octa-coordinated having the square antiprism geometry with the D4d symmetry and connected along the crystallographic a-axis forming a zigzag chain. These chains are further connected by the ligands in three-dimensional crystallographic space. Compounds 2 and 3 were subjected to variable temperature magnetic susceptibility measurements and photoluminescence studies. Magnetic studies reveal that compound 2 possesses antiferromagnetic coupling whereas compound 3 shows ferromagnetic interaction at temperatures above ca. 40 K. The emission spectra of compounds 2 and 3 combine the intra-4f emission of the Ln ions with that of the ligand, depending on the selected temperature, pointing out that the energy transfer processes are thermally activated. In addition, compound 2 presented an invariant 5D4 lifetime behaviour at temperatures between 15 and 300 K. Theoretical analysis showed that the long-lived lifetimes of the free ligand's excited states and the intramolecular energy transfer rate invariability are responsible for such abnormal behaviour.

Based on the organic ligand 2,2′-(((pyridine-2,6-diylbis(methylene))bis((pyridin-2-ylmethyl)-azanediyl))-bis(methylene))diphenol (H2L), and dysprosium salts with different anions, two mononuclear and one dinuclear complexes, namely, [Dy(L)(H2O)](ClO4)·2CH3CH2OH (1), [Dy(L)(NO3)] (2) and [Dy2(L)(dbm)4] (3, Hdbm = dibenzoylmethane), were synthesized and structurally and magnetically characterized. In complexes 1 and 3, the Dy centers are octa-coordinated with triangular dodecahedral (local D2d symmetry) environments. Complex 1 is dimeric by hydrogen bond interactions between coordinated water molecules. In complex 3, two DyIII ions are linked by two phenoxy oxygen atoms to form a dinuclear cluster. The DyIII ion in complex 2 is nine-coordinated and adopts a spherical capped square antiprism geometry with a C4v symmetry. Magnetic measurements and theoretical calculations reveal that the magnetic couplings between two phenoxyl-bridging DyIII ions in complex 3 are antiferromagnetic and mostly originate from the exchange coupling. Both complexes 1 and 2 exhibit single molecule magnet behaviors under zero direct-current field with effective energy barriers of 50.94 K and 12.26 K, respectively. Complex 3 only exhibits frequency-/temperature-dependent out-of-phase signals, and no peak is observed.

A novel [DyIIINaI] complex, [DyNa(L)2(MeOH)]·MeOH (1, H2L = N,N′-bis(2-oxy-3-methoxybenzylidene)-1,2-phenylenediamine), and a zigzag 1D chain based on the [DyIIINaI2] subunit, [DyNa2(L)2(NO3)]n·MeOH (2), were obtained by employing a multidentate Schiff base ligand H2L reacting with Dy(NO3)3·5H2O, NaN3 and NMe4OH·5H2O in MeOH or reacting with Dy(NO3)3·5H2O and NaOH in methanol. Structural analyses revealed that the DyIII in 1 and 2 is sandwiched between two L2− ligands, namely, the DyIII ion was coordinated by four phenoxido O and four amine N atoms from two L2− ligands. SHAPE software calculations and structural analysis indicated that the coordination geometry of DyIII in 1 and 2 is a distorted square antiprism (D4d), but the distortion degree of DyIII in 1 was smaller than that in 2. Additionally, in 1, one NaI is located on one of the N2O2 planes, and the NaI is coordinated by three phenoxido O and three methoxy O atoms from two L2− ligands and one coordinated MeOH molecule. However, in 2, two NaI ions are located on each of the N2O2 planes, in which the coordination environment of each NaI is completed by three phenoxido O atoms, three methoxy O atoms and two O atoms from one NO3− ion. Moreover, the [DyIIINaI2] units are linked into a zigzag 1D chain by nitrate anions. ac magnetic susceptibility measurements revealed that both complexes 1 and 2 exhibit field-induced single ion magnet behavior under a 1000 Oe dc field, with values of the effective energy barrier (Ueff) of 65.33(1) K for 1 and 84.23(1) K for 2. Interestingly, the Ueff values of 1 and 2 are both higher than the corresponding value of 40.1 K for a reported complex with the coordination geometry of a bicapped triangular prism. The moderate SIM performance of 1 and 2 in the Dy(III)-based SIMs with a SAP coordination geometry could be ascribed to the compressed SAP coordination environment of DyIII ions, dipole–dipole interactions and the deviation of the anisotropic axes from the S8 axis.

Endohedral group14-based clusters with the encapsulation of a transition metal, which are termed [TM@Em]n− (TM = transition metal and E = group-14 elements), have lots of potential applications and have been used as interesting building blocks in materials science. Nevertheless, their electronic structures and stability mechanism remain unclear. In this paper, we systematically study the geometries, electronic structures, and bonding properties of [TM@E9]n− clusters which are the smallest endohedral group-14-based clusters synthesized so far, by using density functional theory (DFT) calculations. The calculation results reveal the important role of TMs in affecting the structures and bonding interactions in the [TM@E9]n− cluster. In the presence of a TM, the cluster geometry could change from a monocapped square antiprism (C4v) for empty [E9]4− cages to a tricapped trigonal prismatic geometry (D3h) for [TM@E9]n−. By using the energy decomposition analysis (EDA) method, the bonding properties between the endohedral TM and E9 cluster have been thoroughly investigated. It was found that the origin of stability of these clusters is from the large electrostatic attraction with significantly reduced Pauli repulsion. In the case of orbital interactions, the π back-donations from d orbitals of the TM to the cluster make important contributions. More interestingly, the 1D-chain and 2D-sheet nanostructures based on the [Ni@E9] cluster have been theoretically predicted. The band structure and density of states analysis revealed that all of these nanostructures are metallic and their excellent thermodynamic stability has been confirmed by using ab initio molecular dynamics (AIMD) simulations.

A triangular prismatic metal-organic cage based on mixed valence copper ions has been designed and synthesized by using metallocycle panels and pillar ligands. The triangular prism will be quickly transformed to a 10-nuclear cage upon an external chemical stimulus, which features a bicapped square antiprism structure. This prismatic cage can act as a catalyst for oxidation of aromatic alcohols to their corresponding aromatic aldehydes with high yields at room temperature under O2 atmosphere.

The study reveals the relationship between structural and spectroscopic characteristics of lanthanide dipivaloylmethanates with 2,2′-bipyridine derivatives [Ln(DPM)3L] (Ln = Eu, Tb; L = 2,2′-bipyridine, 4,4′-dimethyl-2,2′-bipyridine, 4,4′-diphenyl-2,2′-bipyridine) and fluorinated β-diketonates [Ln(β)3Bpy] (β = TTFA, TFAA, BTFA) with the CN (Ln3+) = 8 and the LnN2O6 coordination polyhedron in the form of a square antiprism. We discuss structural regularities resulting from the difference between Eu–O and Eu–N bond lengths in β-diketonates due to the changes in donor-acceptor properties of substituents and the steric factor. The effect of the main distortion Δ = r(Eu–N) – r(Eu–O) of the Eu coordination polyhedron on the luminescence spectra and vibrational Raman spectra is considered. A qualitative correlation is demonstrated between the relative intensity of the 5D0–7F2 (Eu3+) electric dipole transition, which characterizes the degree of distortion of the nearest environment of the Eu3+ ion, and the lifetimes of excited electronic states 5D0 (Eu3+) and 5D4 (Tb3+). The contribution of nonradiative processes caused by high-frequency vibrations of ligands to the decay rate of 5D0 (Eu3+) and 5D4 (Tb3+) levels is discussed. The Raman spectra are analyzed in terms of studying the changes in vibrational frequencies of the Bpy molecule depending on the distortion Δ of the Eu coordination polyhedron.

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 $${\text{O}{-}\text{H}}\cdots{\text{Cl}}$$ 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.

The peptide is an important class of biological targeting molecule; herein, a new bifunctional octadentate non-macrocyclic H4octapa, tBu4octapa-alkyl-NHS, which is compatible with solid-phase peptide synthesis and thus useful for radiopeptide preparation, has been synthesized. To preserve denticity, the alkyl-N-hydroxylsuccinimide linker was covalently attached to the methylene–carbon on one of the acetate arms, yielding a chiral carbon center. According to density-functional theory (DFT) calculations using [Lu(octapa-alkyl-benzyl-ester)]− as a simulation model, the chirality has minimal effects on the complex geometry; regardless of the S-/R-stereochemistry, DFT calculations revealed two possible geometric isomers, distorted bicapped trigonal antiprism (DBTA) and distorted square antiprism (DSA), due to the asymmetry in the chelator. To evaluate the biological behavior of the new bifunctionalization, two well-studied PSMA (prostate-specific membrane antigen)-targeting peptidomimetics of varying hydrophobicity were chosen as proof-of-principle targeting vector molecules. Radiolabeling both bioconjugates with lutetium-177 was highly efficient at room temperature in 15 min at micromolar chelator concentration pH = 7. Both the in vitro serum challenge and the lanthanum(III) challenge studies revealed complex lability, and notably, progressive bone accumulation was only observed with the more hydrophobic linker (i.e. H4octapa-alkyl-PSMA617). This in vivo result informs potential alterations exerted by the linker on the complex geometry and stability, with an appropriate biological targeting vector adopted for such evaluations.

Based on a multidentate Schiff-base ligand, N,N′-bis(2-hydroxy-5-methyl-3-formylbenzyl)-N,N′-bis-(pyridin-2-ylmethyl)ethylenediamine (H2L), two binuclear DyIII compounds, with formulas [Dy2(L)(NO3)3(CH3O)] (1) and [Dy2(L)(NO3)3(CH3CH2O)] (2), have been synthesized under different solvent systems. The DyIII ions in 1 and 2 adopt monocapped square antiprism coordination geometries, while different structural distortions can be observed. The two DyIII ions in 1 and 2 are bridged by two phenoxide atoms of one L2− ligand and one bridged CH3O−/CH3CH2O− oxygen node, leading to an approximate fusiform Dy2O3 core. The different DyIII–Obridged node distances, DyIII–Obridged node–DyIII angles and DyIII⋯DyIII distances can be observed. Magnetic studies reveal that 1 and 2 display slow magnetic relaxation behaviours under a zero direct-current field with the effective energy barriers (Ueff) of 114.17 K and 171.23 K, respectively. Furthermore, compound 2 possesses the highest Ueff in nine-coordinated Dy2 compounds. The M versus H data exhibit weak butterfly-shaped hysteresis loops at 2 K for 2. The rare CH3O−/CH3CH2O−-bridged nine-coordinated binuclear DyIII single-molecule magnets (SMMs) significantly regulate and enhance the Ueff of compounds 1 and 2. To deeply understand their different magnetic behaviours, the magnetic anisotropies and magnetic interactions of 1 and 2 were studied by ab initio calculations. These findings demonstrate an efficient approach for regulating and enhancing the magnetic anisotropy barriers using a bridged CH3O− anion or CH3CH2O− anion.

Three new main group ferrocenyldithiocarbamate complexes, viz., {Pb[(FcCH2)(CH2CH2OH)(NCS2)]2}·(FcCH2-3-oxazolidine-2-thione)·(H2O) (1), {Sb[(FcCH2)(CH2CH2OH)(NCS2)]3} (2) and {Bi[(FcCH2)(CH2CH2OH)(NCS2)]3} (3), (Fc = ferrocenyl) have been synthesized and characterized by elemental analyses and IR, 1H and 13C NMR spectroscopy as well as X-ray crystallography. The X-ray analysis of 1 indicates distorted trigonal bipyramidal geometry around Pb(II) and a cyclised product, 3-ferrocenylmethyl-oxazolidine-2-thione (4), co-crystallizes with 1. The geometry around Sb(III) in 2 is pseudo-octahedral, while 3 forms a dimer, displaying distorted square antiprism geometry around the Bi(III) center. Several attempts to synthesize the pure cyclised product 3-ferrocenylmethyl-oxazolidine-2-thione (4) using Pb(II) salts failed but 4 was fortuitously obtained in an attempt to synthesize the Cu(I) cluster by the comproportionation of {Cu[(FcCH2)(CH2CH2OH)(NCS2)]2} using copper powder. Interestingly, varying the reaction time yielded another completely desulfurized cyclised product 3-ferrocenylmethyl-oxazolidine-2-one (5). Both 4 and 5 have been characterized using spectroscopic techniques and X-ray crystallography, and the possible mechanism for the conversion of {Cu[(FcCH2)(CH2CH2OH)(NCS2)]2} to 3-ferrocenylmethyl-oxazolidine-2-thione (4) has been explained with the help of periodic UV-Vis and ESI-MS experiments. This investigation will pave a new pathway for the synthesis of similar cyclised products using similar safe and sustainable reaction conditions.

Three di-nuclear DyIII complexes [Dy2(H2L)2(tfa)]·Cl·3DMF (1), [Dy2(H2L)2(MeO)(SCN)]·MeOH (2) and [Dy2(H2L)2(MeOH)Cl]·Cl·2MeOH (3) were synthesized and structurally and magnetically characterized. The Dy1/Dy2 centers in these complexes are all nine-coordinate with spherical capped square antiprism (local C4v symmetry) environments. All complexes display single-molecule magnet (SMM) behavior under zero applied dc field with their properties dependent on the nature of the magnetic interactions between the DyIII ions. Ab initio calculations substantiate that all DyIII ions show a weakly axial crystal-field environment with the exception of one of the DyIII ions in complex 2. The ground Kramers doublets show modest amounts of quantum tunneling of magnetization that gets blocked by the interaction between the DyIII ions, leading to a thermally activated slow relaxation of magnetization. The interaction between the ions is ferromagnetic and mostly originates from the dipolar interaction. However, anti-ferromagnetic intermolecular interaction plays an important role and in the case of complex 2 it is sufficiently strong to mask the ferromagnetic intramolecular interaction.

By employing mixed ligands, a new trinuclear dysprosium complex [Dy3(dbm)3(L)4](ClO4)2·CH2Cl2·2MeOH (1, Hdbm = dibenzoylmethane; HL = 2-methoxy-6-((quinolin-8-ylimino)methyl)phenol) was synthesized by a one-pot reaction. According to structural characterization, all the 8-coordinated Dy(iii) sites are well arranged with slightly distorted square antiprism (D4d) geometries. Magnetic measurements reveal that 1 exhibits typical single-molecule magnetic behavior at zero magnetic field and shows rarely open hysteresis loops up to 3 K among open-ring {Dy3} SMMs, where the relaxation time remains very stable under the protection from the Dy-Dy magnetic coupling in the open-ring arrangement of Ising spins.

A series of homodinuclear β-diketone lanthanide(III) complexes, formulated as [(acac)4Ln2(L1)] (Ln3+ = Dy3+ (1), Tb3+ (2), and Gd3+ (3), respectively) were first synthesized based on a closed-macrocyclic ligand (H2L1) derived from the [2 + 2] cyclocondensation of 4-tert-butyl-2,6-diformylphenol and o-phenylenediamine in the presence of lanthanide acetylacetonates. Subsequently, by using the above compounds as building blocks to assemble directly with another Schiff base ligand, N,N′-bis(5-chlorosalicylidene)-o-phenylenediamine (H2L2), three new homodinuclear sandwich-type lanthanide complexes with the general formula [Ln2(L1)(L2)2] (Ln3+ = Dy3+ (4), Tb3+ (5), and Gd3+ (6), respectively) were further designed and prepared. Single-crystal X-ray analyses show that the central Ln3+ ion adopts a distorted square antiprism conformation with D4d local symmetry. Magnetic studies reveal ferromagnetic interaction between Dy3+ and Tb3+ centres and zero-field slow relaxation of magnetization for Dy complexes 1 and 4. The corresponding magneto-structural correlations of SMMs 1 and 4 were further discussed by theoretical calculations and with experimental outcomes.

Here, we report our trials to regulate the luminescence performance of the macrocyclic samarium(III) complex and prepare four excellent luminescent Sm(III) complex-doped poly(methylmethacrylate) (PMMA) composites. Four 23-membered [1 + 1] Schiff-base macrocyclic mononuclear Sm(III) complexes, Sm-2a–Sm-2d, originating from dialdehydes with different pendant arms and 1,2-bis(2-aminoethoxy)ethane, have been constructed by the template method. Crystal structures reveal that every Sm(III) ion with the coordination geometry of a distorted bicapped square antiprism is capsulated by the macrocyclic cavity environment forming the “lasso-type” protection. Relative photophysical properties of macrocyclic Sm(III) complexes are carefully investigated in solid-state, methanol solution, and doped PMMA film, and all these show characteristic emissions of the Sm(III) ion associated with satisfactory lifetimes and quantum yields in all media, which could be comparable to reported outstanding examples. Especially, the luminescence performance for this type of Sm(III) complex could be regulated in the solid state by the use of different functional groups in the pendant arm while it is not achieved in solution and the doped PMMA composite. High emitting and air-stable plastic materials could be obtained when these Sm(III) complexes are doped in PMMA with 0.1 wt % mixing ratio, and the corresponding maximum lifetime and quantum yield are 61.2 μs and 0.63% in the case of complex Sm-2a, respectively. We believe that these highly luminescent “lasso-type” Sm(III) complexes and doped PMMA composites are valuable references in the design of luminescent lanthanide(III) hybrid materials.

The first complexes of cerium tetrafluoride in solutions were investigated by 19 F NMR and IR spectroscopy. The temperature dependence of the 19 F NMR spectra was, studied and it was concluded that mobile equilibrium exists between the molecular adduct and singly charged ionic forms, including geometric isomers. The static probability of stereoisomer formation [CeF 4 (dmso) 4 ] was calculated using the square antiprism configuration and, based on the relative intensity of the 19 F NMR resonance signals, they were assigned to possible stereoisomers. Quantum-chemical calculations of the structure of the isomer [CeF 4 (dmso) 4 ], the isomer [CeF 3 (dmso) 5 ] + and [CeF 5 (dmso) 3 ] - , showing their thermodynamic stability, were performed.

One-step cyclization of a tetraazamacrocycle 5 with 70% yield in a 25-g scale was performed. Its chiral DOTA derivatives, L4, has ∼93% of TSAP coordination isomer in its Eu(III) and Yb(III) complexes in aqueous solution. [GdL4]5– exhibits a high relaxivity, making it a promising and efficient MRI contrast agent. High luminescence dissymmetry factor (glum) values of 0.285 (ΔJ = 1) for [TbL3]– and 0.241 (ΔJ = 1) for [TbL4]5– in buffer solutions were recorded.

A series of lanthanide(III) oxamate complexes of formula Na[Eu(4-HOpa)4(H2O)]∙2H2O (1), Na[Gd(4-HOpa)4(H2O)]∙2H2O (2), Na[Dy(4-HOpa)4(H2O)]∙2H2O (3), and Na[Ho(4-HOpa)4(H2O)]∙2H2O (4) (4-HOpa = N-4-hydroxyphenyloxamate) were synthesized and characterized. The crystal structures of complexes 1–4, as well as the oxamate ligand in the ethyl ester acid form (Et[4-HOpa]), were elucidated by single crystal X-ray diffraction. 1–4 are isostructural, and they crystallize in the P21/n space group of the monoclinic system. The crystal structures of 1–4 consist of mononuclear lanthanide(III) complex anions, [Ln(4-HOpa)4(H2O)]− (Ln = Eu3+, Gd3+, Dy3+, and Ho3+), coordinated sodium(I) countercations, and crystallization water molecules, resulting in a 2D NaILnIII supramolecular coordination network. The coordination sphere of Ln3+ ions consists of square-face capped square antiprism (SAPRS-9). Magnetic properties were investigated for 1–4 in the 2–300 K temperature range using polycrystalline samples. Complex 2 exhibits an unusual and rare slow-relaxation of the magnetization for Gd3+ ions under DC applied field of 1.0 kOe, behaving as a field-induced single-ion magnet as occurs for the Dy3+ complex 3. The Eu3+ complex 1 has a nonmagnetic ground state, while the Ho3+ compound 4 behave as a paramagnet, and do not exhibit relaxation of the magnetization with or without an applied field.

The first complexes of cerium tetrafluoride in solutions have been studied by 19F NMR and IR spectroscopy. The temperature dependence of the 19F NMR spectra has been explored, and conclusion has been made that dynamic equilibrium between the molecular adduct and singly charged ionic forms, including geometric isomers, exists in solution. The statistical probability for the formation of [CeF4(dmso)4] stereoisomers of square antiprism configuration has been calculated, and their assignment to possible stereoisomers have been made on the basis of relative intensities of the 19F NMR signals. Quantum-chemical calculations of the structure of one of the possible isomers have been performed for the [CeF4(dmso)4] molecular adduct, [CeF3(dmso)5]+ cation, and [CeF5(dmso)3]– anion to show their thermodynamic stability.

International audience; An alternative synthesis for M(κ2-bipy)4 (M = La, Ce) and [Li(thf)4][M(κ2-bipy)4] (M = Tb, Dy) and the crystal structures for M = La, Ce, and Tb are described. The isomorphous and isostructural neutral molecules, M = La and Ce, are polymeric in the solid-state, as are those of M = Sm and Eu, which were reported in earlier work. The polymeric network is built from eight coordinate units whose geometry in all four cases is that of a square prism. The known molecules, M = Yb and Lu, are also polymeric, but the eight coordinate units have dodecahedral geometries. The structure of the anions in the separated ion pair, [Li(thf)4][M(κ2-bipy)4], in which Tb is reported in this work and Lu is known, are monomeric with geometries that are between that of a square antiprism and a dodecahdron. The electronic structure, from CASSCF multireference quantum mechanical calculations, shows that the electronic ground states for M = La and Lu are multiconfigurational spin doublets and those for the M = Ce and Yb are multiconfigurational spin triplets. This is confirmed by magnetic susceptibility studies as a function of temperature that are consistent with the metals (La, Ce, Sm, Tb, Dy, Yb, and Lu) being trivalent, as are the LIII-edge XANES spectra (Ce, Yb), and divalent for Eu. The multiconfigurational nature of the ground states, developed from CASSCF molecular orbital calculations, renders a single Lewis structure and a single reference molecular orbital representation misleading. The results from the multireference calculations are extended to the other lanthanide molecules and are the genesis of a new model for understanding the magnetic properties of these molecules.

The crystal structures of chelates formed between each stable paramagnetic lanthanide ion and the octadentate polyamino carboxylate ligand DOTMA are described. A total of 23 individual chelates structures were obtained; in each chelate the coordination geometry around the metal ion is best described as a twisted square antiprism (torsion angle -25.0°--31.4°). Despite the uniformity of the general coordination geometry provided by the DOTMA ligand, there is a considerable variation in the hydration state of each chelate. The early Ln3+ chelates are associated with a single inner sphere water molecule; the Ln-OH2 interaction is remarkable for being very long. After a clear break at gadolinium, the number of chelates in the unit cell that have a water molecule interacting with the Ln3+ decreases linearly until at Tm3+ no water is found to interact with the metal ion. The Ln-OH2 distance observed in the chelates of the later Ln3+ ions are also extremely long and increase as the ions contract (2.550-2.732 A). No clear break between hydrated and dehydrated chelates is observed; rather this series of chelates appear to represent a continuum of hydration states in which the ligand gradually closes around the metal ion as its ionic radius decreases (with decreased hydration) and the metal drops down into the coordination cage.

Lanthanide pyrrole-2-carboxylates [{Ln(L)3(H2O)2}·H2O]n (Ln = Eu, Gd, Tb) were synthesized and investigated using single crystal X-ray diffraction and optical spectroscopy (luminescence, luminescence excitation and vibrational IR spectra). The europium pyrrole-2-carboxylate crystallizes as a 2D network structure in the P21/c space group. The Eu3+ coordination polyhedron formed by five carboxylic groups and two water molecules can be described as a distorted single-capped square antiprism. The luminescence spectra indicate a low symmetry of the charge distribution around the Ln3+ ion that corresponds to the C1 symmetry of the coordination environment of Eu3+ ion in the [{Eu(L)3(H2O)2}·H2O]n crystal lattice. The low-energy ligand–metal charge transfer (LMCT) state was identified in the europium compound. The shortening of the 5D0 (Eu3+) lifetime in the 230–295 K temperature region, when the compound is heated from 77 to 295 K, and the low luminescence intensity of the europium pyrrole-2-carboxylate are caused by the participation of the LMCT state in quenching processes. The energy of activation determined for the 5D0 – LMCT crossover is 3900 ± 100 cm−1.

Homo-trinuclear [Zn3(L)(μ2-OAc)2(H2O)].CH2Cl2 (1) and hetero-pentanuclear [Zn4(L)2Eu(NO3)3(H2O)] (2) and [Zn4(L)2Nd(NO3)3(H2O)]·CH3CH2OH (3) complexes containing a coumarin-skeleton bis(salamo) ligand H4L, were successfully prepared and characterized via the means of elemental analyses, single crystal X-ray crystallography, FT-IR, UV–Vis absorption spectroscopy and Hirshfeld surfaces analyses. Complex 1 is a 1:3 ((L)4−:ZnII) structure, and complexes 2 and 3 are 2:4:1 ((L)4−:ZnII:LnIII) structure. All ZnII atoms in complexes 1–3 occupied the N2O2 sites are five-coordinated with geometries of slightly distorted tetragonal pyramid and trigonal bipyramid. Rare earth metal (EuIII and NdIII) atoms are both coordinated with phenolic oxygen atoms, and eight-coordinated with the square antiprism geometries in complexes 2 and 3. Water molecules as coordinating solvents participate in the coordination. Supra-molecular structures are built by C H…π and hydrogen bonding interactions in complexes 1–3. Moreover, Hirshfeld surfaces analyses of complexes 1–3 were also analysed in detail. Most important of all, luminescences of complexes 1–3 were discussed.

The reaction of the Mannich base ligand (H2L = N, N'-dimethyl- N, N'-bis(2-hydroxy-3-methoxy-5-methylbenzyl)ethylenediamine) with Co(OAc)2·4H2O and Ln(III) nitrate salts (Ln = Gd, Tb, and Dy) under basic conditions afforded three carbonato-bridged isostructural tetranuclear heterometallic Co(II)-Ln(III) complexes (Co2Gd2L2(μ4-CO3)2(NO3)2] (1), [Co2Tb2L2(μ4-CO3)2(NO3)2] (2), and [Co2Dy2L2(μ4-CO3)2(NO3)2] (3)) by atmospheric CO2 fixation. In all structures, two dinuclear [(CoIIL)LnIII(NO3)] units are linked via two μ4-carbonato groups to form the tetranuclear CoII2LnIII2 core. The geometry around two penta-coordinated Co(II) ions is distorted square pyramid, and that around two nona-coordinated Ln(III) ions is intermediate between "spherical tricapped trigonal prism" and "spherical capped square antiprism" in all complexes. The complexes (1-3) showed catecholase-like and phenoxazinone-synthase-like catalytic activities. The kcat values calculated for the catecholase-like reaction were 254.5, 272.4, and 291.3 h-1, and for the phenoxazinone-synthase-like reaction they were 2930.6, 2965.2, and 2998.5 h-1 for complexes 1-3, respectively. The probable pathways for these two oxidase reactions have been proposed by the analyses of mass spectral data. For all of the compounds, the variable temperature magnetic susceptibility and isothermal magnetization data were investigated. The complexes exhibited overall ferromagnetic behavior, which was evident from the isothermal magnetization curves. AC magnetic susceptibility measurements revealed the slow relaxation of magnetization in complexes 2 and 3 but very negligible in 1. The activation energy barriers ( Ueff) for the slow relaxation process were evaluated and found to be 1.99, 2.79, and 8.98 K for 1, 2, and 3, respectively.

Four isostructural dinuclear lanthanide complexes based on 4-azotriazolyl-3-hydroxy-2-naphthoic acid (H3ATNA) and 3-hydroxy-2-naphthoic acid (H2NA) ligands, {[Ln2(HATNA)2(HNA)2(H2O)4]·6DMF} (Ln = Dy (1), Tb (2), Sm (3), Eu (4); DMF = N, N-dimethylformamide) have been prepared and characterized by X-ray diffraction crystallography, dc/ac magnetic characterization, and fluorescent spectrometry. The crystallographic data reveal dinuclear lanthanide cores of complexes 1-4, bridged by phenoxo and μ1,3 carboxyl groups. Each nine-coordinated Ln(III) ion is located in a slightly distorted monocapped square antiprism. The ligand of H3ATNA displays a unique antenna effect in complex 4. Complexes 1-3 display only two ligand-centered fluorescent emissive peaks around 450 and 600 nm, and complex 4 shows four characteristic Eu(III)-centered emission bands at 593, 618, 653, and 698 nm under excitation at 348 nm. Complex 1 exhibits single-molecule magnet behavior that is rationalized through ab initio calculations.

Three new LnIII-MOFs, {[Dy1.5(TAPB)1.5(DMF)]·9DMF}n (Ln = Dy (1), Er (2), Ho (3); TAPB = 4, 4′, 4″-(triazine‑2, 4, 6‑triyl‑tris‑(benzene‑4, 1-diyl)) tribenzoate), have been synthesized via a solvothermal method by using a trigonal N-containing tricarboxylate as the ligand. The coordination geometries around the central metal ions in the MOFs exhibit different deviations from ideal square antiprism (D4d symmetry) because of the coordinated solvent molecules. The ac magnetic susceptibility data is consistent with single chain magnet behavior for Dy(III) and Er(III) complexes, which have been studied by the noncritical scaling theory.

An important goal in chemistry is to prepare F-rich transition metal fluorides due to the high oxidation states and potential applications such as oxidating and fluorinating agents. Thus far, the highest F stoichiometry in the neutral transition metal fluorides is 7. Here, we identify a hitherto unknown IrF8 compound through first-principles swarm-intelligence structure search calculations under high pressure. The three identified IrF8 phases exhibit typical molecular crystal characters, showing +8 oxidation state in Ir. The spatial symmetry of the basic building block in the three IrF8 phases gradually increases with pressure (e.g., dodecahedron → square antiprism → quasicube). The pressure-induced faster increase of Ir 5d orbital energy level with respect to F 2p provides a strong charge transfer driving force from Ir 5d to F 2p, facilitating the formation of F-rich compounds. More interestingly, the predicted electron affinities of the three predicted IrF8 phases are comparable/larger than that of PtF6...

We report the crystal structure of Ba(CN3H4)2 as synthesized from liquid ammonia. Structure solution based on X-ray diffraction data suffers from a severe pseudo-tetragonal problem due to extreme scattering contrast, so the true monoclinic symmetry is detectable only from neutron powder diffraction patterns, and structure solution and refinement was greatly aided by density-functional theory. The symmetry lowering is due to slight deviations of the guanidinate anion from the mirror plane in space group P 4 ‾ b2, a necessity of hydrogen bonding. At 300 K, barium guanidinate crystallizes in P21/c with a=6.26439(2) A, b=16.58527(5) A, c=6.25960(2) A, and a monoclinic angle of β=90.000(1)°. To improve the data-to-parameter ratio, anisotropic displacement parameters from first-principles theory were incorporated in the neutron refinement. Given the correct structural model, the positional parameters of the heavy atoms were also refinable from X-ray diffraction of a twinned crystal. The two independent guanidinate anions adopt the all-trans- and the anti-shape. The Ba cation is coordinated by eight imino nitrogens in a square antiprism with Ba-N contacts between 2.81 and 3.04 A. The IR and Raman spectra of barium guanidinate were compared with DFT-calculated phonon spectra to identify the vibrational modes.

Four new coordination polymers based on the use of the [Cr(pyim)(C2O4)2]− species as a metalloligand, namely [LiCr(pyim)(C2O4)2(MeOH)]n (1), {[CaCr2(pyim)2(C2O4)4]·2MeOH}n (2), {[SrCr2(pyim)2(C2O4)4(H2O)]·0.45MeOH·4.55H2O}n (3) and {[CdCr2(pyim)2(C2O4)4]·MeOH}n (4) [pyim = 2-(2′-pyridyl)imidazole] have been synthesized and characterized by elemental analyses, IR spectra and X-ray diffraction on single crystals. Complex 1 is a neutral heterobimetallic chain where the tris(chelated) chromium(III) unit acts as a bis-bidentate ligand towards {Li(MeOH)}+ fragments through its two oxalate ligands, each lithium ion being five-coordinate in a intermediate surrounding between square pyramidal and trigonal bipyramidal. The structure of 2 consists of neutral oxalato-bridged chromium(III)-calcium(II) double chains of single chirality [all the tris(chelated) chromium centres have the same chirality either Λ or λ] and methanol molecules of crystallization. Each calcium ion in 2 exhibits a square antiprism environment which is built by four bidentate oxalate ligands from four [Cr(pyim)(C2O4)2]− units. Neutral oxalato-bridged chromium(III)-strontium(II) double chains also occur in 3 with methanol and water molecules of crystallization, each alkaline-earth cation being nine-coordinate in a monocapped square antiprism environment which is defined by a water molecule and eight oxalate-oxygens from four [Cr(pyim)(C2O4)2]− units. The CrIII2MII2 loops [M = Ca (2) and Sr (3)] within each double chain are planar. The structure of 4 is also made of neutral oxalato-bridged chromium(III)-cadmium(II) double chains but in contrast to 2 and 3, the chirality of the tris(chelated) chromium unit in 4 is alternated in each loop and the adjacent CrIII2CdII2 loops are not planar but form a dihedral angle of 84.8°. The potential use of the [Cr(pyim)(C2O4)2]− entity as a metalloligand in designing heterobimetallic compounds is analyzed and discussed.

A complete library of Zr and Hf complexes bearing salen ligands were synthesized and characterized by various spectroscopic techniques and X-ray crystallography. The stoichiometry of the reactions for the preparation of these complexes alters on varying the ligands and leads to different products. For Zr we observe mononuclear and dinuclear complexes. In the dinuclear complexes, each Zr centre adopts a distorted octahedral geometry. The metal centers are bridged with two isopropoxide groups and each metal center has two terminal isopropoxide moieties attached to it. The mononuclear Zr complex adopts a distorted square antiprism geometry. Hf complexes adopt both mononuclear distorted octahedral and distorted square antiprism geometries. The catalytic activity towards the ring-opening polymerization (ROP) of lactide (LA) and e-caprolactone (e-CL) was assessed. These compounds were found to be potent catalysts, resulting in the formation of products with very high number average molecular weight (Mn) values with controlled dispersity (Đ). All the complexes were found to be highly active towards the copolymerization of cyclohexene oxide (CHO) with CO2 generating polycarbonates showing good turnover frequencies (TOF). In the cases of styrene oxide (SO) and propylene oxide (PO), the formation of cyclic styrene carbonate and cyclic propylene carbonate, respectively, is witnessed. The steric and electronic nature of the substituents of ancillary ligands influences the catalytic activity of these complexes, with the electron donating substituent reducing the activity. The kinetics of L-LA, rac-LA and e-CL polymerization was studied in detail and revealed that the polymerization follows first-order kinetics. The mechanisms of respective polymerization processes were also investigated. Analysis of the MALDI-TOF and 1H NMR spectra of a low Mn oligomer from rac-LA polymerization reveals that the isopropoxide group initiates the ROP.

The reaction of the lanthanide(III) β-diketonate salt (Dy(beac)3·2H2O) with a bidentate chelating ligand 5-(2-hydroxy-5-methylbenzylidene)-8-hydroxylquinoline (HL) afforded the tetranuclear Dy(III) cluster, [Dy4(μ3-OH)2L6(beac)4]·10CH3CN (1). The elemental analysis (EA), powder X-ray diffraction (PXRD), single-crystal X-ray diffraction and magnetic properties of 1 have been characterized. The X-ray structural analysis reveals that cluster 1 contains one Dy4 center with a rhombus-shaped arrangement, and each Dy(III) ion of 1 is located in a distorted square antiprism geometrical configuration. Magnetic properties study indicate that 1 shows single-molecule magnet behavior with larger energy barrier (ΔE/kB) of 78.3 K and τ0 = 4.4 × 10−7 s.

The combination of LnIII ions (GdIII, TbIII or DyIII) and a pyrazole nitronyl nitroxide radical results in three isomorphous complexes, namely, [Ln(hfac)3(NIT-Pyz)]2 (Ln = Gd(1), Tb(2), Dy(3); hfac = hexafluoroacetylacetone; NIT-Pyz = 2-{3-pyrazolyl}-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide). Single crystal X-ray diffraction studies revealed that all of them are composed of two crystallographically independent mononuclear systems, in which the central LnIII ions are coordinated by three hfac and one bidentate chelating NIT-Pyz radical. The central LnIII ions are all in square antiprism geometry (D4d) polyhedron configurations. Based on the spin Hamiltonian calculations, there exist antiferromagnetic couplings in the GdIII-NIT radical system in complex 1. Complexes 2 and 3 show frequency-dependent out-of-phase signals in a zero field indicating single-molecule magnetic behavior. Moreover, Tb's complex (2) shows a single thermal relaxation process with an energy barrier of 26 K. For Dy's complex (3), the Orbach and Raman processes both contribute to the magnetic relaxation behaviors.

Herein we report a stable and high-performance Dy(iii) single-ion magnet (SIM) showing an energy barrier of 944 K under zero dc field, with an open hysteresis loop up to 6 K. To the best of our knowledge, this is the highest energy barrier for a square antiprism as well as phosphine oxide based Dy-SIMs, reported so far.

In this paper we report a novel probe based on a luminescent 23-membered [1 + 1] Schiff-base macrocyclic mononuclear Sm(iii) complex Sm-2e, originating from the dialdehyde H2Qe and 1,2-bis(2-aminoethoxy)ethane precursors, which is synthesized by the Sm(iii) ion template method. X-ray structural analyses confirm that each ten-coordinate Sm(iii) center with the coordination geometry of a distorted bicapped square antiprism is fully encapsulated by a flexible macrocyclic ligand H2L2e to form a "lasso-type" architecture, and this architecture could enable efficient energy transfer in various solvents confirmed by long lifetimes (33.5-65.2 μs) and high quantum yields (0.23-0.76%) of the Sm(iii) ion. Simultaneously, complex Sm-2e could serve as a probe for sensing organic solvents. Particularly, this complex probe Sm-2e exhibits a highly selective, rapid and sensitive response to tetrahydrofuran (THF), which is easily distinguished by a large absorption shift, even visible to the naked eye, and complete fluorescence quenching. Moreover, the limit of detection for THF is about 0.20% determined by titration experiments, and good selectivity for THF could still be realized in mixture solvents. Consequently, this colorimetric and "turn off" fluorescent probe Sm-2e could be a valuable candidate as a sensor material for sensing THF which has been rarely reported.

A family of polyhedral metal-imidazolate cages based on the flexible bi-imidazole ligand L and Cu2+ ions have been synthesized and characterized, featuring an unusual Cu10L8 bicapped square antiprism structure (or Johnson solids, J17) with an adaptable cavity. These metal–organic cages encapsulate anions, and they will expand or compress after they are filled with different-sized anions.

A series of binuclear dysprosium compounds, namely, [Dy(api)]2 (1), [Dy(api)]2·2CH2Cl2 (2), [Dy(Clapi)]2·2C4H8O (3), and [Dy(Clapi)]2·2C3H6O (4) (H3api = 2-(2-hydroxyphenyl)-1,3-bis[4-(2-hydroxyphenyl)-3-azabut-3-enyl]-1,3-imidazoline; H3Clapi = 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 H3api/H3Clapi with DyCl3·6H2O in different solvent systems. Structural analysis reveals that each salen-type ligand provides a heptadentate coordination pocket (N4O3) to encapsulate a DyIII ion and all of the DyIII centers in 1–4 adopt a distorted square antiprism geometry with D4d symmetry. Magnetic studies showed that compound 1 did not exhibit single-molecule magnetic (SMMs) behavior. With the introduction of different lattice solvents, compounds 2–4 showed filed-induced slow magnetic relaxation with barriers Ueff of 18.2 K (2), 28.0 K (3) and 16.4 K (4), respectively. Ab initio calculations were employed to interpret the magnetization behavior of 1–4. The combination of experimental and theoretical data reveal the importance of the weak exchange interaction between the DyIII ions in the observation of slow magnetic relaxation, and a relaxation mechanism has been developed to rationalize the observed difference in the Ueff values. The different lattice solvents influence Dy–O–Dy bond angles and thus alter the torsion of the square antiprism geometry, consequently resulting in distinct magnetic interactions and the magnetic behavior.

Four novel homoleptic triple-decker lanthanide complexes, [Ln2(L)(Cl-salphen)2]·0.5ClCH2CH2Cl (Ln3+ = Gd3+ (1), Ho3+ (2), Tb3+ (3), and Dy3+ (4)), have been designed and synthesized based on a Schiff base ligand N,N′-bis(5-chlorosalicylidene)-o-phenylenediamine (Cl-salphenH2) and the building blocks [(acac)4Ln2(L)]; these complexes were derived from a closed-macrocyclic ligand (H2L) obtained by the [2 + 2] template condensation of 2,6-diformyl-4-methylphenol and 1,3-diaminopropane in the presence of lanthanide acetylacetonates. Single-crystal X-ray analyses show that central Ln3+ ions adopt distorted square antiprism conformations with D4d symmetry. Theoretical analysis and magnetic measurements reveal that Dy complex 4 behaves as a typical SMM with the characteristics of slow magnetic relaxation behavior and intermetallic ferromagnetic interaction.

A thorough structural characterization of the La(NO3)3 salt dissolved into several mixtures of ethyl ammonium nitrate (EAN) and methanol (MeOH) with EAN molar fraction χEAN ranging from 0 to 1 has been carried out by combining molecular dynamics (MD) and X-ray absorption spectroscopy (XAS). The XAS and MD results show that changes take place in the La3+ first solvation shell when moving from pure MeOH to pure EAN. With increasing the ionic liquid content of the mixture, the La3+ first-shell complex progressively loses MeOH molecules to accommodate more and more nitrate anions. Except in pure EAN, the La3+ ion is always able to coordinate both MeOH and nitrate anions, with a ratio between the two ligands that changes continuously in the entire concentration range. When moving from pure MeOH to pure EAN, the La3+ first solvation shell passes from a 10-fold bicapped square antiprism geometry where all the nitrate anions act only as monodentate ligands to a 12-coordinated icosahedral structure in pure EAN where the nitrate anions bind the La3+ cation both in mono- and bidentate modes. The La3+ solvation structure formed in the MeOH/EAN mixtures shows a great adaptability to changes in the composition, allowing the system to reach the ideal compromise among all of the different interactions that take place into it., The structural properties of the La(NO3)3 salt dissolved into EAN/methanol mixtures were characterized by molecular dynamics and X-ray absorption spectroscopy. The La3+ solvation shell undergoes significant changes with increasing the ionic liquid content of the mixture, progressively losing methanol molecules to accommodate more and more nitrate anions. The La3+ solvation structure shows great adaptability to composition changes, passing from a 10-fold bicapped square antiprism geometry in pure methanol to a 12-coordinated icosahedral complex in EAN.

Porous biomaterials are often used to treat large bony defects or fractured vertebras. Most of such biomaterials are made of metals and their alloys and have a pre-defined, fixed shape. Due to their predefined fixed shape, however, they are not suitable for implantation through minimally invasive surgical procedures. To overcome this problem, we designed three different deployable non-assembly mechanisms, which were manufactured using selective laser melting. These deployable geometries, including a bicapped cube, a bicapped trigonal antiprism, and a bicapped square antiprism, possess a large aspect ratio in their retracted state. Upon the application of an external force, they expand radially into their deployed load-bearing configuration. Using non-assembly manufacturing, revolute joints, wavelike elements, rigid rods and restrictions could be integrated into the design. The designs were manufactured in such a way that the least amount of support structures was required during the fabrication process. Additionally, the deployable structures were functional immediately after printing. Mechanical tests were performed to determine the forces required to deploy the designed structures and to determine their failure load. A maximum change of 322 ± 7% in the circumdiameter was found for the bicapped trigonal antiprism while the bicapped square antiprism showed the largest reduction in the height (61 ± 1%). A maximum force of 10.3 ± 1.6 N was required during the deployment process of the bicapped square antiprism 3. The bicapped antiprisms could support up to 1212 ± 45.5 N before they failed, while the bicapped cubes failed under a force of 232 ± 5.5 N. The elongated geometry of our designs makes them ideal for implantation using minimally invasive surgical procedures. Given the fact that these are the first non-assembly deployable bone substitutes manufactured using selective laser melting, further studies are required to make them suitable as orthopedic implants.

In the work, the first principles calculation and low temperature spectra were utilized to investigate the modification on Nd3+ clusters in SrF2 crystal. The results show that structures of the clusters vary greatly and it depends on the ionic radius of rare-earth La3+, Nd3+, Gd3+ and Y3+. The cubic sublattice centers are stable in large size rare-earth La3+- and Nd3+-doped SrF2, and the square antiprism centers are more stable in smaller size Gd3+- and Y3+-doped crystals. It suggests that the square antiprism clusters become more stable with decreasing ionic radius in going from La3+, Nd3+, Gd3+ to Y3+, while the cubic sublattice centers become unstable. Based on the results, the mixed [Nd3+-La3+] and [Nd3+-Gd3+] clusters are also calculated. Stability of square antiprism clusters is improved with increasing concentration of Gd3+ in [Nd3+-Gd3+] clusters, and that weakened when codoped with La3+. The results reveal that characteristics of the mixed centers depend on species and contents of the ingredient rare-earth ions. Local environment of the active ions could therefore be modified by codoping the other rare-earth ions, which agreed well with the tunable absorption and emission spectra of Nd3+:SrF2 modified by La3+, Gd3+ and Y3+. The varied cluster structures provide us a methodology towards designing of new rare-earth-doped fluoride materials.

This work reports on the structural and photophysical characterization of D4-symmetrical octanuclear circular LnIII helicates, [(R)- or (S)-iPr-Pybox]8(LnIII)8(THP)8 (where Ln = Eu and Tb, THP = trianionic tris-β-diketonate, and iPr-Pybox = chiral bis(4-isopropyl-2-oxazolinyl)pyridine). X-ray crystallographic analysis revealed that the octanuclear circular helicate possesses square antiprism architecture and consists of four [(R)- or (S)-iPr-Pybox]2LnIII2(THP)2 asymmetric units arranged in a closed ring form. Ligand-to-ligand interactions between the THP and the iPr-Pybox ligands have successfully directed formation of enantiopure, homoconfigurational (Δ,Δ,Δ,Δ,Δ,Δ,Δ,Δ)-R and (Λ,Λ,Λ,Λ,Λ,Λ,Λ,Λ)-S isomers. All of the nonacoordinated LnIII ions are identical and exhibit a distorted capped square antiprism (CSAP) geometry. Upon excitation of the ligand absorption band (λ = 360 nm), the circular helicates display characteristic EuIII (red, 5D0 → 7FJ, J = 0-4) or TbIII (green, 5D4 → 7FJ, J = 6-3) core f-f luminescence. The overall emission quantum yields of the circular EuIII and TbIII helicates are 0.145 and 0.0013, respectively, in chloroform. The EuIII and TbIII complexes exhibit remarkable circularly polarized luminescence (CPL) activity at their magnetic dipole transition with observed luminescence dissymmetry factors |glum| of 1.25 (5D0 → 7F1, λ = 592 nm) and 0.25 (5D4 → 7F5, λ = 541 nm), respectively. Exceptional |glum| values of the circular EuIII helicates highlight the visible intensity difference between left and right circularly polarized emissions of R and S isomers in chloroform and PMMA thin film.

The combination of atomic orbitals to form hybrid orbitals of special symmetries can be related to the individual orbital polynomials. Using this approach, 8-orbital cubic hybridization can be shown to be sp3d3f requiring an f orbital, and 12-orbital hexagonal prismatic hybridization can be shown to be sp3d5f2g requiring a g orbital. The twists to convert a cube to a square antiprism and a hexagonal prism to a hexagonal antiprism eliminate the need for the highest nodality orbitals in the resulting hybrids. A trigonal twist of an Oh octahedron into a D3h trigonal prism can involve a gradual change of the pair of d orbitals in the corresponding sp3d2 hybrids. A similar trigonal twist of an Oh cuboctahedron into a D3h anticuboctahedron can likewise involve a gradual change in the three f orbitals in the corresponding sp3d5f3 hybrids.

An unusual self-assembled hetero-bimetallic [Ni(II)-Sm(III)] coordination polymer, [Ni(L)Sm(NO3)3(4,4&prime, bipy)]n, is prepared through a hexadentate chelating ligand 2,2&prime, [1,2-ethylenedioxybis(nitrilomethylidyne)]diphenol (H2L). The Ni(II)-Sm(III) coordination polymer is validated through elemental analyses, Fourier-transform infrared and UV-Visible spectroscopies, and X-ray single-crystal diffraction. The Ni(II) atom forms a twisted six-coordinated octahedron, and the Sm(III) atom is ten-coordinated, adopting a twisted bicapped square antiprism. An infinite three-dimensional-layer supramolecular structure is obtained through extensive &pi, &middot, &pi, stacking and intermolecular hydrogen bonding interactions. The polymer has a good antibacterial effect against Staphylococcus aureus.

Accurate knowledge of rare earth elements (REE) speciation in high pressure – high temperature fluids is required to model REE transport and precipitation in subduction zones and magmatic-hydrothermal environments, and the formation of rare metal deposits. Recent experiments (lanthanum, ytterbium, erbium) have demonstrated that REE chloride complexes are the main REE form in many hydrothermal fluids (Migdisov et al., 2016). However, the speciation of yttrium (Y(III)), a cation with an ionic radius similar to that of Ho(III), remains poorly constrained in chloride-rich hydrothermal solutions. We used ab initio molecular dynamics (MD) simulations to calculate the nature of Y(III)-Cl complexes and the thermodynamic properties of these species at temperatures up to 500 °C and pressures of 800 bar and 1000 bar. The MD results were complemented by in situ X-ray absorption spectroscopy (XAS) measurements. Our results indicate that at temperatures below 200 °C, chloro-complexes do not form readily, even in highly concentrated brines. At ambient condition, the Y(III) aqua ion binds to eight water molecules in a square antiprism geometry, which is consistent with previous ab initio studies (Ikeda et al., 2005a). The thermodynamic integration method was employed to calculate the formation constants (log K Θ ) of Y(III)-Cl− complexes in two simulation boxes containing different Y:Cl ratios; we obtained very consistent results of the standard log K Θ of the individual complexes from the two independent calculations, which confirms that the thermodynamic integration method is reliable and not significantly affected by technical limitations in box size, box composition, or simulation time. Based on the derived formation constants, we fit modified Ryzhenko–Bryzgalin (MRB) equation of state parameters, which enable extrapolation of the formation constants at elevated temperature and pressure. The results are consistent with the XAS data, and show that the stability of Y(III)-Cl complexes increases with increasing temperature, Y(III) forming high order Cl− complexes (up to YCl4−) in high salinity solutions at high temperature and pH = 3. We also compare the extrapolated log K Θ with the available data for other REE at 150 °C, 200 °C and 250 °C. At 200 °C, yttrium behaves more like a heavy REE, but from 200 °C to 250 °C, the formation constants of Y(III)-Cl complexes increase dramatically and behave more like the light REE. The difference of Cl− dominant species between Ho(III) (HoCl2+) and Y(III) (YCl2+) may account for the formation of anomalous Y/Ho ratios in some hydrothermal environments.