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A whole series of [Ln(H2O)4(Ala)2]26+ dimeric cationic lanthanide complexes with both L- and D-alanine enantiomers was synthesized. The single-crystal X-ray diffraction at 100 and 292 K shows the formation of two types of dimers (I and II) in crystals. Between the dimer centers, the alanine molecules behave as bridging (&mu, 2-O,O&rsquo, ) and chelating bridging (&mu, 2-O,O,O&rsquo, ) ligands. The first type of bridge is present in dimers I, while both bridge forms can be observed in dimers II. The IR and vibrational circular dichroism (VCD) spectra of all L- and D-alanine complexes were registered in the 1750&minus, 1250 cm&minus, 1 range as KBr pellets. Despite all the studied complexes are exhibiting similar crystal structures, the spectra reveal correlations or trends with the Ln&ndash, O1 distances which exemplify the lanthanide contraction effect in the IR spectra. This is especially true for the positions and intensities of some IR bands. Unexpectedly, the &nu, (C=O) VCD bands are quite intense and their composed shapes reveal the inequivalence of the C=O vibrators in the unit cell which vary with the lanthanide. Unlike in the IR spectra, the &nu, (C=O) VCD band positions are only weakly correlated with the change of Ln and the VCD intensities at most show some trends. Nevertheless, this is the first observation of the lanthanide contraction effect in the VCD spectra. Generally, for the heavier lanthanides (Ln: Dy&ndash, Lu), the VCD band maxima are very close to each other and the mirror reflection of the band of two enantiomers is usually better than that of the lighter Lns. DFT calculations show that the higher the multiplicity the higher the stability of the system. Actually, the molecular geometry in crystals (at 100 K) is well predicted based on the highest-spin structures. Also, the simulated IR and VCD spectra strongly depend on the Ln electron configuration but the best overall agreement was reached for the Lu complex, which is the only system with a fully filled f-shell.

In first approximation the binding of an electron in lanthanide 4f q ground states changes with q in a characteristic zigzag shape that is independent on type of compound. Those shapes have been parameterized in past publications and are used to construct host referred binding energy (HRBE) or vacuum referred binding energy (VRBE) schemes showing the lanthanide 4f q level locations with respect to the host valence bands or to the vacuum level. There is experimental evidence for a slight compound dependence, and a model explaining that has appeared recently (Dorenbos, 2019). This all implies that the parameters for constructing HRBE and VRBE schemes need to be revised and a compound dependence needs to be introduced as a second order approximation. In this work the improved parameters are derived from the 3 r d and 4 t h ionization potentials of the lanthanide atoms. In compounds, as explained by the chemical shift model, the free ion binding energy curves undergo an upward shift due to Coulomb repulsion from anion ligands and they undergo a tilt due to the lanthanide contraction. In this work we will use the nephelauxetic parameter β to add a compound dependence. Its main effect is an increased binding in the 4f q ground states for the lanthanides from the right hand branch (q > 7) of the zigzag curves. The same applies for the 4f q − 1 5d excited states with ( q − 1 ) > 7 . Collected spectroscopic data on divalent and trivalent lanthanides from more than 1000 different compounds have been analyzed to arrive at the proposed revised parameters for the 4f q and 4f q − 1 5d binding energy curves.

A series of lanthanide coordination polymers (Ln-CPs), with the formula of {[Ln(L)3(CH3OH)(H2O)]n} (Ln = Sm (1), Eu (2), HL = 2-chloroisonicotinic acid) and {[Ln(L)3(H2O)2]n} (Ln = Dy (3), Tb (4)), were synthesized under solvothermal condition. This series display two different 1D chains due to the lanthanide contraction: complexes 1 and 2, based on light Sm and Eu, respectively, consist of paddle-wheel [Ln2(COO)4] dimmers through double μ2-COO bridges, and complexes 3 and 4 with heavy Dy and Tb, respectively, show 1D [Ln(COO)2]n chains. The luminescent measurements indicate the typical emissions of corresponding Ln3+ ions in complexes 1–4. Furthermore, complexes 2 and 4 display significant luminescent response for Fe3+ ions with high quenching constant. The result indicates that complexes 2 and 4 can act as luminescent probes for Fe3+ ions with relatively high sensitivity and selectivity.

The structural, magnetic, electrical, and dilatation properties of the rare-earth NdCoO3 and SmCoO3 cobaltites were investigated. Their comparative analysis was carried out and the effect of multiplicity fluctuations on physical properties of the studied cobaltites was considered. Correlations between the spin state change of cobalt ions and the temperature dependence anomalies of the lattice parameters, magnetic susceptibility, volume thermal expansion coefficient, and electrical resistance have been revealed. A comparison of the results with well-studied GdCoO3 allows one to single out both the general tendencies inherent in all rare-earth cobaltites taking into account the lanthanide contraction and peculiar properties of the samples containing Nd and Sm.

The ligand H3L and its corresponding tris(phenolato) lanthanide complexes L-Tb, L-Gd, L-Yb and L-Lu were synthesized. The X-Ray crystal structures demonstrated a monocapped octahedron environment of the lanthanide ion, with exclusion of all solvent molecules from the coordination sphere due to the protection by the tert-butyl groups. The coordination bond distances followed the lanthanide contraction, with Ln-O bond lengths in the range 2.148–2.217 A and Ln-Nimine bond lengths in the range 2.405–2.535 A. Each of the complexes showed three one-electron oxidation processes. These potentials changed as a function of the lanthanide due to the difference in size of the metal ions. Both chemical and electrochemical oxidations of these complexes permitted the one-electron oxidised species to be generated. They all show a sharp absorption band at around 420 nm in their UV-Vis spectra, which demonstrated phenoxyl radical formation. Consistently, the radical species L-Lu+ displays a resonance at g = 2.001 in its EPR spectrum. The other cations are EPR-silent or difficult to detect due to magnetic interactions, confirming the proximity of the phenoxyl radical to the metal centre. For both L-Lu+ and L-Yb+ DFT calculations predict the radical to be delocalized over the three arms. The L-Tb and L-Yb complexes experienced a quenching of the luminescence upon oxidation to the radical species whereby the quenching of up to 83% in the visible region and 93% in the NIR was observed.

Structural and fluorescence properties of Ho3+/Yb3+ co-doped germanosilicate glasses have been modified by tailoring the composition using lanthanide additive Lu2O3. Raman spectra and X-ray Photoelectron spectra reveal that the addition of Lu2O3 can change the structure by increasing non-bridging oxygens (NBO) in this glasses. Meanwhile, an improved thermal stability (ΔT: from 110 to 187 °C) has also been obtained via Lu3+ ‘lanthanide contraction’. Futhermore, the positive effect of changed glass structure gives excellent fluorescence properties by the decreasing cross relaxation process which are proved by the experimental upconversion, near-infrared and mid-infrared fluorescence spectra. Additionally, a double enhancement of a 2.0 μm emission has been achieved successfully in this silica-germanate glass with 7 mol% Lu3+ addition, which possesses a larger emission cross section (4.41 × 10−21 cm2) at 2022 nm. These results indicate that the optimized emission of Ho3+ for optical fiber laser can be achieved by tuning the glass structure using lanthanide additive Lu2O3.

Twenty-eight new Heusler phases REPd2Mg, REPd2Cd, REAg2Mg, REAu2Mg and REAu2Cd with different rare earth elements were synthesized from the elements in sealed niobium ampoules in a water-cooled sample chamber of an induction furnace. The samples were characterized by powder X-ray diffraction. The cell volumes show the expected lanthanide contraction. The structures of YPd2Cd, GdPd2Cd, GdAu2Cd, Y1.12Ag2Mg0.88 and GdAg2Mg were refined based on single crystal diffractometer data. The magnetic properties were determined for fifteen phase pure samples. LuAu2Mg is a weak Pauli paramagnet with a susceptibility of 1.0(2) × 10−5 emu mol−1 at room temperature. The remaining samples show stable trivalent rare earth ions and most of them order magnetically at low temperatures. The ferromagnet GdAg2Mg shows the highest ordering temperature of TC = 98.3 K. 113Cd and 89Y MAS NMR spectra of YAu2Cd and YPd2Cd confirm the presence of unique crystallographic sites. The resonances are characterized by large Knight shifts, whose magnitude can be correlated with electronegativity trends.

A series of centrosymmetric dinuclear lanthanide complexes, including Gd​III (1), Dy​III (2), Ho​III (3), Er​III (4) and Yb​III (5), have been synthesized and studied for the effects of lanthanide contraction on their magnetic properties. As a result of probing the magnetic properties of the Gd​III analogue, 1, a weak antiferromagnetic intramolecular interaction was confirmed, with J = −0.01 cm−1 and g = 2.01. The DyIII complex, 2, was found to exhibit larger values of gx and gy in the ground doublet of individual DyIII ions via ab initio calculations, and thus did not act as a SMM. Interestingly, the ErIII (4) and YbIII (5) complexes exhibited slow relaxation of the magnetization under an applied dc field with effective energy barriers (Ueff) of 21 K and 22 K, respectively.

Lanthanide contraction was used for helicity fine-tuning and helix winding control of single-helical tetranuclear complexes LZn3Ln (Ln = La–Lu); heavier lanthanides formed a tighter helix with a higher M/P ratio and gave a more abundant partially-coiled structure, resulting in 14-step structural control of the helical complexes.

Three series of lanthanide coordination polymers with formula [Ln2(PDC)3(H2O)2(DMF)]·4H2O (type I) (Ln = La 1, Pr 2, Sm 3), [(CH3)2NH2][Ln2(PDC)3(HCOO)(H2O)3]·2H2O (type II) (Ln = Tb 4, Ho 5) and [Ln(HPDC)3(H2O)2]·H2O (type III) (Ln = Er 6, Lu 7) (H2PDC = pyridine-3,5-dicarboxylic acid), have been successfully synthesized by the solvothermal reaction of pyridine-3,5-dicarboxylic acid (H2PDC) with the corresponding lanthanide nitrate. Compounds 1–3 are isomorphous and all crystallize in triclinic space group P, showing a 3D microporous framework of pcu topology with square channels along the b-axis. Isostructural compounds 4 and 5 show the same 2D layer network of (4,4)-grid in the monoclinic P21/c space group. Isomorphic 6 and 7 crystallize in the monoclinic Cc space group and present 1D zigzag chains which expand to a 3D supramolecular structure through π⋯π stacking interactions. The structural diversity of these three classes of compounds may be attributed to the effect of lanthanide contraction. They were characterized by infrared spectra (IR), elemental analysis (EA), thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD), and X-ray single crystal diffraction. Furthermore, the catalytic properties of these compounds were investigated and experiments revealed that compounds 1–3 show size-selective catalytic performance for cyanosilylation reactions and could be reused without losing their catalytic activity.

Kinetic energy dependent reactions of Th(+) with H2, D2, and HD were studied using a guided ion beam tandem mass spectrometer. Formation of ThH(+) and ThD(+) is endothermic in all cases with similar thresholds. Branching ratio results for the reaction with HD indicate that Th(+) reacts via a statistical mechanism, similar to Hf(+). The kinetic energy dependent cross sections for formation of ThH(+) and ThD(+) were evaluated to determine a 0 K bond dissociation energy (BDE) of D0(Th(+)-H) = 2.45 ± 0.07 eV. This value is in good agreement with a previous result obtained from analysis of the Th(+) + CH4 reaction. D0(Th(+)-H) is observed to be larger than its transition metal congeners, TiH(+), ZrH(+), and HfH(+), believed to be a result of lanthanide contraction. The reactions with H2 were also explored using quantum chemical calculations that include a semiempirical estimation and explicit calculation of spin-orbit contributions. These calculations agree nicely and indicate that ThH(+) most likely has a (3)Δ1 ground level with a low-lying (1)Σ(+) excited state. Theory also provides the reaction potential energy surfaces and BDEs that are in reasonable agreement with experiment.

RE 2 Pd 2 In, RE 2 Pd 2 Sn compounds (RE = rare earth) absorb, depending on the rare earth (RE) element, different amounts of hydrogen. The parent compounds RE 2 Pd 2 In show the linear decrease of both lattice parameters and the unit cell volume with the increasing atomic number of RE, attributed to the lanthanide contraction. All the compounds absorb at least 2 H/f.u.; the tetragonal structure is merely expanded. The expansion is anisotropic (Δ c / c > Δ a / a ), and for RE = Tb, Dy, Ho, and Er the lattice even contracts along the a -axis (Δ a / a c / c still weakly increases. A higher H concentration can be achieved in the compounds with light rare earths (La, Nd, both for In and Sn), which then become amorphous. The magnetic ordering temperatures of all studied RE 2 Pd 2 In compounds are dramatically reduced by the hydrogenation, typically to the temperature range below 1.8 K.

Zintl phases are renowned for their diverse crystal structures with rich structural chemistry and have recently exhibited some remarkable heat- and charge-transport properties. The ternary bismuthidesRELi3Bi2(RE= La–Nd, Sm, Gd, and Tb) (namely, lanthanum trilithium dibismuthide, LaLi3Bi2, cerium trilithium dibismuthide, CeLi3Bi2, praseodymium trilithium dibismuthide, PrLi3Bi2, neodymium trilithium dibismuthide, NdLi3Bi2, samarium trilithium dibismuthide, SmLi3Bi2, gadolinium trilithium dibismuthide, GdLi3Bi2, and terbium trilithium dibismuthide, TbLi3Bi2) were synthesized by high-temperature reactions of the elements in sealed Nb ampoules. Single-crystal X-ray diffraction analysis shows that all seven compounds are isostructural and crystallize in the LaLi3Sb2type structure in the trigonal space groupP\overline{3}m1 (Pearson symbolhP6). The unit-cell volumes decrease monotonically on moving from the La to the Tb compound, owing to the lanthanide contraction. The structure features a rare-earth metal atom and one Li atom in a nearly perfect octahedral coordination by six Bi atoms. The second crystallographically unique Li atom is surrounded by four Bi atoms in a slightly distorted tetrahedral geometry. The atomic arrangements are best described as layered structures consisting of two-dimensional layers of fused LiBi4tetrahedra and LiBi6octahedra, separated by rare-earth metal cations. As such, these compounds are expected to be valance-precise semiconductors, whose formulae can be represented as (RE3+)(Li1+)3(Bi3−)2.

A short overview of fundamental chemistry of lutetium and of structural characteristics of lutetium coordination complexes, as relevant for understanding the properties of lutetium-177 radiopharmaceuticals, is presented. This includes basic concepts on lutetium electronic structure, lanthanide contraction, coordination geometries, behavior in aqueous solution and thermodynamic stability. An illustration of the structure and binding properties of the most important chelating agents for the Lu(3+) ion in aqueous solution is also reported with specific focus on coordination complexes formed with linear and macrocyclic polydentate amino-carboxylate donor ligands.

Three series of lanthanide coordination polymers, {[Ln(L)(H2O)2]·NO3·2H2O }n (Ln = La 1, Pr 2), {[Ln2(L)2(NO3)(H2O)2]·Cl·6H2O}n (Ln = Nd 3), {[Ln(L)(H2O)2]·Cl·3H2O}n (Ln = Sm 4, Eu 5, Gd 6, Tb 7, Dy 8, Ho 9, Er 10, Tm 11, Yb 12, and Lu 13) (H3L = 4-carboxy-1-(3,5-dicarboxy-benzyl)-pyridinium chloride), have been successfully synthesized under hydro(solvo)thermally conditions. Single-crystal X-ray diffraction analyses revealed that compounds 1–3 all crystallize in triclinic space group P1, but they display different three-dimensional structures with diverse dinuclear subunits. In contrast, compounds 4–13 display the same layer structures in the triclinic space group P1. The structural difference of these two classes of compounds is derived from the effect of lanthanide contraction. Powder X-ray diffraction (PXRD) and thermogravimetric analyses of compounds 1–13 have also been investigated and discussed in detail. The solid-state luminescent properties of compounds 4, 5, 7, and 8 were characterized, and t...

Single crystals of LnCo2Al8 (Ln = La–Nd, Sm, Yb) were grown via the metal-flux growth technique and characterized by single crystal X-ray diffraction. LnCo2Al8 adopts the CaCo2Al8-structure type with space group Pbam and unit cell dimensions of a ≈ 12.4 A, b ≈ 14.4 A, and c ≈ 4.0 A. The unit cell volume of LnCo2Al8 (Ln = La–Nd, Sm, Yb) systematically decreases as a function of rare earth, consistent with the lanthanide contraction, except for YbCo2Al8, indicating a divalent Yb2+ state. LnCo2Al8 (Ln = Ce, Pr, Nd) show high temperature Curie–Weiss paramagnetism, and LnCo2Al8 (Ln = Pr, Nd) orders magnetically at TN = 5.6 and 8.7 K, with a fluctuating moment consistent with the trivalent oxidation state of the lanthanides. LnCo2Al8 (Ln = La–Nd, Sm, Yb) are metallic, with CeCo2Al8 having a residual resistivity ratio (RRR) of 20. We present the crystal growth, structural, magnetic, and electrical properties of single crystalline LnCo2Al8 (Ln = La–Nd, Sm, Yb).

Complexes of lanthanide bromides with tricyclohexylphosphine oxide (Cy3PO) form three distinct structural classes. Type I complexes LnBr3(Cy3PO)3 have been structurally characterised for Ln = La, Pr, Nd, Gd and Ho and are molecular 6 coordinate with a distorted meridional octahedral arrangement. Type II complexes are based on pentagonal bipyramidal [Ln(Cy3PO)n(H2O)5]3+ structures and fall into three subsets; n = 2 and 3 have been isolated for Ln = Lu and n = 4 with Ln = La, Dy, Er and Yb. The structures of [Lu(Cy3PO)2(H2O)5]Br3·2EtOH and [Ln(Cy3PO)2(H2O)5]Br3 (Ln = Dy, Er, Yb) have been determined. When n = 2 both ligands are directly coordinated to the metal whilst complexes in which n = 4 have two ligands bonded to the metal and two hydrogen bonded to the coordinated water molecules. Analysis of the bond distances shows that the lanthanide contraction accounts for about 99% of the observed trends. The infrared spectra of the complexes give a good means of identifying the structural types produced. 31P NMR show that the Type I complexes are fluxional in solution and that the Type II complexes undergo ligand exchange between metal and H-bonded ligands. Analysis of the lanthanide induced shifts indicates that the Type II complexes are isostructural in solution.

Forming solid solutions, as an effective strategy to improve thermoelectric performance, has a dilemma that alloy scattering will reduce both the thermal conductivity and carrier mobility. Here, an intuitive way is proposed to decouple the opposite effects, that is, using lanthanide contraction as a design factor to select alloying atoms with large mass fluctuation but small radius difference from the host atoms. Typical half-Heusler alloys, n-type (Zr,Hf)NiSn and p-type (Nb,Ta)FeSb solid solutions, are taken as paradigms to attest the validity of this design strategy, which exhibit greatly suppressed lattice thermal conductivity and maintained carrier mobility. Furthermore, by considering lanthanide contraction, n-type (Zr,Hf)CoSb-based alloys with high zT of ≈1.0 are developed. These results highlight the significance of lanthanide contraction as a design factor in enhancing the thermoelectric performance and reveal the practical potential of (Zr,Hf)CoSb-based half-Heusler compounds due to the matched n-type and p-type thermoelectric performance.

Montana Tech has been engaged in fundamental research on the processing of critical materials for more than a decade. Efforts include examining novel reagents for the flotation of Rare Earth Minerals (REMs). For this paper, research results on a collector, salicyl hydroxamic acid (SHA), are presented. Various REMs were examined and include the rare earth oxides (REOs), carbonates (RECs), and phosphates (REPs) of a suite of Rare Earth Elements (REEs). Differences are attributed to solution and surface chemistry, coordination number, and ionic diameter. SHA adsorption follows an ion-exchange process that leads to chemisorbed and surface-precipitated states, depending mostly on pH. Many effects are directly attributed to lanthanide contraction. Results should also be applicable to other REM/collector systems and further suggest that REM flotation should consider dual collectors.

The tripodal ligand TREN-(3,5-di-tert-butylsalicylidene)3 (H3L) was synthesized and its tris(phenolato) lanthanide complexes L-Ln (Ln = NdIII, EuIII, TbIII, GdIII, ErIII, YbIII and LuIII) were prepared. The X-Ray crystal structures confirm that each metal ion resides in a similar monocapped octahedral geometry, excluding water molecules from the coordination sphere. The coordination bond distances are in agreement with the lanthanide contraction, with Ln-O bond lengths in the range 2.139-2.216 A. The complexes show three reversible monoelectronic oxidation waves, which are assigned to the successive oxidation of the phenolate moieties to phenoxyl radicals. The L-Nd complex is the easiest to oxidize, with E = 0.11, E = 0.21 and E = 0.34 V vs. Fc+/Fc, due to the larger size of the lanthanide ion. The ΔE1/2 value (ΔE1/2 = E-E) is correlated to the lanthanide radius, with values of 0.10 V for L-Nd and 0.22 V for L-Lu. The monoradical species were persistent in solution, allowing for their characterisation. All exhibit a distinct absorption band at around 445 nm due to the phenoxyl π-π* transitions. The EPR spectrum of L-Lu+ consists of a single resonance at giso = 1.999, confirming the radical nature of the oxidized product. Most of the other complexes (L-Gd, L-Er, L-Yb) show a quenching of the LnIII-based resonances upon oxidation, indicative of magnetic interactions between the metal and the radical spins. The L-Ln (L = Nd, Er, Yb) complexes exhibit a metal-based luminescence upon excitation of the ligand. A significant quenching of the luminescence was observed upon radical formation: 92%, 83% and 79% respectively for L-Nd+, L-Er+ and L-Yb+.

Interest in the bioinorganic chemistry of lanthanides is growing rapidly as more and more lanthanide-dependent bacteria are being discovered. Especially the earlier lanthanides have been shown to be preferentially utilized by bacteria that need these Lewis acids as cofactors in their alcohol dehydrogenase enzymes. Here, we investigate the impact of the lanthanide ions lanthanum(iii) to lutetium(iii) (excluding Pm) on the catalytic parameters (vmax, KM, kcat/KM) of a methanol dehydrogenase (MDH) isolated from Methylacidiphilum fumariolicum SolV. Kinetic experiments and DFT calculations were used to discuss why only the earlier lanthanides (La-Gd) promote high MDH activity. Impact of Lewis acidity, coordination number preferences, stability constants and other properties that are a direct result of the lanthanide contraction are discussed in light of the two proposed mechanisms for MDH.

A series of lanthanide metal-organic frameworks (Ln-MOFs) are synthesized through solvothermal conditions with 1,3-bis(4-carboxyphenyl) imidazolium (H2L). Owing to the lanthanide contraction effect, two different types of Ln-MOFs, namely, {[Ln(L)(2)(OH)]center dot 3H(2)O}(n) (Ln:Pr, Nd, Sm) and {[Ln(L)(2)(COO) (H2O)(2)]center dot H2O}(n) (Ln:Eu, Gd, Tb, Dy, Tm, Yb, Y), and their corresponding codoped Ln-MOFs EuxTb1-xL are obtained. With careful adjustment of the relative concentration of the lanthanide ions and the excitation wavelength, the color of the luminescence can be systematically modulated and white light emission can be further successfully achieved. Furthermore, by virtue of the temperature-dependent luminescent behavior, Eu0.2Tb0.8L allows for the design of a thermometer with an excellent linear response to temperature over a wide range, from 40 to 300 K. This work highlights the practical applications of Ln-MOFs for tailoring fluorescent color and even obtaining practical white light emission, and especially for sensing temperature as luminescent thermometers in a single framework by controlling in different ways.

A series of new lanthanoid selenidoantimonates(V) [Ln(en)(tepa)SbSe4] (Ln = La (Ia), Ce (Ib), Pr (Ic); en = ethylenediamine, tepa = tetraethylenepentamine) and [Ln2(tepa)2(μ-OH)2Cl2]-{[Ln(tepa)]2(μ-OH)2(SbSe4)2} (Ln = Y (IIa), Sm (IIb), Gd (IIc), Tb (IId), Dy (IIe), and Tm (IIf)) were solvothermally synthesized and structurally characterized. The structures of Ia-c consist of neutral molecules [Ln(en)(tepa)SbSe4], where the tetrahedral [SbSe4](3-) anion acts as a ligand to chelate the [Ln(en)(tepa)](3+) cation. The structures of IIa-f contain isolated dinuclear [Ln2(tepa)2(μ-OH)2Cl2](2+) cations built up from two [Ln(tepa)Cl](2+) ions linked by two -OH bridging groups and organic decorated {[Ln(tepa)]2(μ-OH)2(SbSe4)2}(2-) anions based on two [Ln(tepa)SbSe4] units bridged by two -OH groups. Although a few lanthanoid selenidoantimonates(V) under solvothermal conditions have been reported, their lanthanide complexes normally appear mononuclear. Hence, IIa-f are rare examples of lanthanoid selenidoantimonates based on dinuclear lanthanide complexes. A preliminary investigation of nine lanthanoid selenidoantimonates(V) shows that the well-known lanthanide contraction has a significant influence on the formation of lanthanoid selenidoantimonates(V) under solvothermal conditions. The absorption edges of all compounds have been investigated by UV-vis spectroscopy, and density functional theory calculations for Ia and IIc have also been performed.

A novel lanthanide metal–organic framework was yielded by a hydrothermal reaction of 5-chloro-6-hydroxypyridine-3-carboxylic acid (5-Cl-6-HOPy-3-CO2H) and Dy2O3 in the presence of oxalic acid [H2(OX)], namely, {[Dy2(1H-5-Cl-6-Opy-3-CO2)2(OX)2(H2O)]·2H2O}∞ (1, 1H-5-Cl-6-Opy-3-CO2− = 1-hydro-5-chloro-6-oxopyridine-3-carboxylate, which was formed by the autoisomerization of single deprotonated 1H-5-Cl-6-HOpy-3-CO2− anion). The dysprosium(III) ions are bridged by oxalate anions to construct an interesting 4-connected layer network with a Schalfli topology symbol of (32·52) (3·53), such layers are connected with each other by the 1H-5-Cl-6-HOpy-3-CO2− anions to form a three-dimensional framework. Magnetic investigations indicated that 1 is a field-induced single-molecule magnet, displaying two-step thermal magnetic relaxation, with an effective thermal barrier of 37.6 K. Surprisingly, a zigzag chain-like gadolinium(III) complex, {[Gd(1H-5-Cl-6-Opy-3-CO2)2(OX)0.5(H2O)3]·6H2O}∞ (2), was isolated using Gd2O3 instead of Dy2O3 owing to the lanthanide contraction effect. Notebaly, a unique F-shaped (H2O)6 supramolecular aggregate exists in the crystal structure of 2.

Two new series of two-dimensional (2-D) lanthanide–silver heterometallic–organic frameworks with the formula [Ln2Ag(IN)2(BPDC)2(H2O)4]·(NO3)·2H2O (1-Ln) (Ln = Nd 1, Eu 2, Tb 3, and Dy 4) and [Ln2Ag(IN)2(BPDC)2(H2O)2]·(NO3)·2H2O (2-Ln) (Ln = Ho 5, Yb 6, HIN = isonicotinic acid, H2BPDC = 2,2′-biphenyldicarboxylic acid) have been hydrothermally synthesized and characterized by single crystal X-ray diffraction, elemental analysis, IR spectroscopy, thermogravimetric analysis (TGA) and powder X-ray diffraction (PXRD). In the structures of these six compounds, BPDC2− ligands link Ln3+ through their carboxylate groups, resulting in the formation of one-dimensional (1-D) {Ln(BPDC)}n infinite chains. These adjacent chains are further connected to each other via the coordination interaction between Ln3+ and carboxylate groups of IN− ligands, as well as the pillared Ag(IN)2 units, giving rise to 2-D layered structures. Although they have similar secondary building units (SBUs), the whole open frameworks of these two types of HMOFs that may be produced by the lanthanide contraction effect are quite different. Isostructural compounds 1–4 (1-Ln) crystallize in the monoclinic C2/c space group and possess a (6,3)-connected topology containing 1-D hexagonal microporous channels along the c axis, while isostructural compounds 5 and 6 (2-Ln) crystallize in the triclinic P space group and present a 2-D network of (4,4)-connected topology with 1-D rhombic channels along the b axis. Meanwhile, solid-state photoluminescence studies of compounds 1–3 and 6 were also conducted at room temperature and the luminescence intensity of 3 and 6 are found to be sensitive to small molecules.

A series of new lanthanoid thioarsenates [Ln(teta)(μ-η(1):η(2):η(1)-As(III)S3)]n {Ln = Ce (Ia), Pr (Ib), Nd (Ic), and Sm (Id); teta = triethylenetetramine} and [Ln(teta)(en)(μ-η(1):η(1):η(1)-As(V)S4)]n {Ln = La (IIa), Ce (IIb), Pr (IIc), and Nd (IId); en = ethylenediamine} were prepared by the solvothermal reaction of K3AsO3, S, LnCl3 and organic amines and structurally characterized. Compounds Ia–d crystallise in the orthorhombic space group Aba2 and display 1-D neutral chains [Ln(teta)(μ-η(1):η(2):η(1)-As(III)S3)]n, which represent the first examples of 1-D organic hybrid lanthanoid sulfides built up from trigonal-pyramidal [As(III)S3](3-) acting as tetradentate bridging ligands to interlink [Ln(teta)](3+) ions, while compounds IIa–d crystallise in the orthorhombic space group P2(1)2(1)2(1) and consist of other 1-D neutral chains [Ln(teta)(en)(μ-η(1):η(1):η(1)-As(V)S4)]n, which are built up from the linkages of the tetrahedral [As(V)S4](3-) ion and the [Ln(teta)(en)](3+) ion. To learn more about the influence of lanthanide contraction on the formation of lanthanoid thioarsenates, three organic hybrid lanthanoid thioarsenates [Ln(teta)(en)As(V)S4] [Ln = Dy (IIIa), Ho (IIIb), and Tm (IIIc)] with the neutral molecular structure type in the monoclinic centrosymmetric space group P2(1)/c are also presented. Their optical and magnetic properties have been investigated, and density functional theory calculations of Ia and IIa have also been performed.

Ten lanthanide coordination polymers have been obtained by the hydrothermal reactions between 3,3′-dimethoxy-2,2′-bipyridine-6,6′-dicarboxylic acid (H2mbpdc) and rare earth ions, in which H2mbpdc undergoes an in situ ligand transformation reaction, giving 3,3′-hydroxy-2,2′-bipyridine-6,6′-dicarboxylic acid (hbpdcH4). The structures are governed by the synergistic effect of lanthanide contraction with diverse coordination modes and conformations of the ligand. They have three structural types from 3D to 2D polymers. Type I for large ions with the general formula [Ln(hbpdcH)(H2O)]n (Ln = LaIII (1), CeIII(2), PrIII (3)), possesses a 6-connected pcu network with unprecedented 2D entangled layers of warp-and-woof threads interwoven by left- and right-handed helical chains; type II for intermediate ions (Ln = EuIII (4), GdIII (5)) and type III for small ions (Ln = TbIII (6), DyIII (7), HoIII (8), ErIII (9), LuIII (10)), with general formula [Ln(hbpdcH)(H2O)2]n. The type II and III comprised 2D Ln-hbpdcH grids. A magnetic study of 6–8 indicated that the coupling interaction between Ln3+ ions is weak. In addition, the photophysical properties of Eu and Tb polymers at room temperature were investigated.

A series of lanthanide microporous coordination polymers, namely, {[Ln4(OBA)6(DMF)(H2O)]·2DMF·3H2O}n [Ln = Nd(1), Sm(2), Eu(3), Gd(4)]; {[Ln4(OBA)6(H2O)2]·3DMF·2H2O}n [Ln = Tb(5), Dy(6)]; {[Ln4(OBA)6(DMF)(H2O)2]·2DMF·4H2O}n [Ln = Tb(7), Dy(8)] (H2OBA = 4,4′-oxybisbenzoic acid, DMF = N,N′-dimethylformamide), have been successfully prepared via solvothermal methods and characterized by FT-IR, photoluminescence spectra, thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction. All of the lanthanide coordination polymers showed three dimensional (3D) metal–organic frameworks. The structural variations in compounds 1–8 may be caused by lanthanide contraction and different coordination modes of V-shaped H2OBA ligands. The luminescence properties of compounds 3, 5 and 7 have been studied in the solid state at room temperature, and all of them displayed metal-based luminescence. Moreover, compounds 4, 6 and 8 exhibited antiferromagnetic coupling within the carboxyl oxygen bridged rare-earth chains.

Four series of new lanthanide coordination polymers, namely [LnL(glu)]n·2nH2O (Ln = Nd (1), Sm (2), Gd (3)), [YbL(glu)]n (4), [LnL(glu)(H2O)]n (Ln = Pr (5), Sm (6), Gd (7), Dy (8), Ho (9), Er (10), Y (11)) and [PrL(glu)(H2O)]n (12) [HL = 2-(2-sulfophenyl)imidazo(4,5-f)(1,10)-phenanthroline, H2glu = glutaric acid] have been hydrothermally synthesized and characterized by elemental analysis, IR spectroscopy and single crystal X-ray diffraction. The isostructural compounds 1–3 exhibit 6-connected 3D networks with the topological type of pcu, containing left- and right-handed helical chains. Compound 4 is a 6-connected 3D network with bsn topology, which contains unique meso-helical chains. Because of the lanthanide contraction, compounds 1–3 and 4 show different structures, which were all synthesized at pH = 4.0 and with the molar ratio of LnIII : HL : H2glu = 2 : 1 : 1. When only the pH value was changed, to 6.0, the resulting isostructural compounds 5–11 show 4-connected 2D sql topology with the point symbol of (44·62). By changing the molar ratio of 2 : 1 : 1 (LnIII : HL : H2glu) to 2 : 1 : 2 at pH = 4.0, compound 12 shows an 8-connected 3D network with bcu topology, which has left- and right-handed helical chains. Photoluminescence spectra of compounds 1–12 have been investigated upon excitation at 370 nm. Magnetic susceptibility measurements exhibited typical paramagnetic behavior for compounds 3 and 7, and weak antiferromagnetic interactions for compounds 8–10.

Two series of new lanthanide coordination polymers have been obtained by solvothermal reaction of Ln(NO3)3 and pamoic acid under different pH values. Both series of compounds show three-dimensional porous frameworks composed of dinuclear Ln(III) subunits. Series B demonstrates fascinating solvent-induced dynamic behaviors in an SCSC (single crystal to single crystal) manner. The capability of activated series B to absorb liquid acetone was investigated by means of 1H NMR spectroscopy, demonstrating the potential of Ln-MOFs as highly efficient and reusable liquid acetone sorbents. In addition, photoluminescence properties of Nd (3), Eu (5) and Yb (10) were measured and discussed. Lanthanide contraction effect also played a crucial role in the formation of each series of complexes. Analysis of the relations between the ionic radius (Ln3+) and the number of f electrons in these complexes indicates that lanthanide contraction effect in both series can be well described by the Raymond model.

Eleven new lanthanide (Ln = Nd-Lu)-thiophene-2,5-dicarboxylic acid (25-TDC)-2,2':6',2''-terpyridine (terpy) coordination polymers () which employ a dual ligand strategy have been synthesized hydrothermally and structurally characterized by single crystal and powder X-ray diffraction. Two additional members of the series ( and ) were made with Ce(3+) and Pr(3+) and characterized via powder X-ray diffraction only. The series is comprised of three similar structures wherein differences due to the lanthanide contraction manifest in Ln(3+) coordination number as well as the number of bound and solvent water molecules within the crystal lattice. Structure type I (Ce(3+)-Sm(3+)) contains two nine-coordinate Ln(3+) metal centers each with a bound water molecule. Structure type II (Eu(3+)-Ho(3+)) features a nine and an eight coordinate Ln(3+) metal along with one bound and one solvent water molecule. Structure type III (Er(3+)-Lu(3+)) includes two eight-coordinate Ln(3+) metal centers with both water molecules residing in the lattice. Assembly into supramolecular 3D networks via π-π interactions is observed for all three structure types, whereas structure types II and III also feature hydrogen-bonding interactions via the well-known C-HO and O-HO synthons. Visible and near-IR luminescence studies were performed on compounds , , , and at room temperature. As a result characteristic near-IR luminescent bands of Pr(3+), Nd(3+), Sm(3+), and Yb(3+) as well as visible bands of Sm(3+) were observed.

A series of new polynuclear lanthanide(III) clusters [Ln4(heda)6(Hheda)2Cl2]Cl4 [Ln = Sm (1a), Eu (1b), Hheda = N-(2-Hydroxyethyl)ethylenediamine] and [Ln6(heda)10(µ-OH)2]Cl6·2H2O [Ln = Y (2a), Gd (2b), Dy(2c), Tb(2d), Ho (2e), Er (2f), Tm(2g)] were solvothermally synthesized and structurally characterized. 1a-b consist of tetra-nuclear lanthanide(III) cluster [Ln4(heda)6(Hheda)2Cl2] built up from two unsaturated [Ln2(heda)3(Hheda)Cl]2+ complex cations via two bridging O atoms of two L− ligands. 2a-g are isostructural and contain hexa-nuclear lanthanide(III) clusters [Ln6(heda)10(µ-OH)2]6+ constructed by the linkages of two unsaturated trinuclear [Ln3(heda)5(µ-OH)] clusters, free Cl− anions as counterions and H2O molecules. Although many transition metal complexes were obtained by using HL ligand as chelating ligand, its polynuclear lanthanide(III) clusters have not been documented to date. 1a-b and 2a-g offer the only examples of polynuclear lanthanide(III) clusters of HL ligand. A preliminary investigation of nine polynuclear lanthanide(III) clusters reveals that the well-known lanthanide contraction has a significant influence on the formation of polynuclear lanthanide(III) clusters under solvothermal conditions. The luminescent properties of 1b and 2d were discussed, and magnetic properties of 1a and 2e were also investigated.

In acidic solution, a serials of water-soluble coordination polymers (CPs) were isolated as zonal 1D-CPs 1,3-propanediaminetetraacetato lanthanides [Ln(1,3-H3pdta)(H2O)5]n·2Cln·3nH2O [Ln=La, 1; Ce, 2; Pr, 3; Nd, 4; Sm, 5] (1,3-H4pdta=1,3-propanediaminetetraacetic acid, C11H18N2O8) in high yields. When 1 eq. mol potassium hydroxide was added to the solutions of 1D-CPs, respectively, two 1D-CPs [Ln(1,3-H2pdta)(H2O)3]n·Cln·2nH2O [Ln=Sm, 6; Gd, 7] were isolated at room temperature and seven 2D-CPs [Ln(1,3-H2pdta)(H2O)2]n·Cln·2nH2O [Ln=La, 8; Ce, 9; Pr, 10; Nd, 11; Sm, 12; Eu, 13; Gd, 14] were isolated at 70 °C. When the crystals of 1–4 were hydrothermally heated at 180 °C with 1–2 eq. mol potassium hydroxide, four 3D-CPs [Ln(1,3-Hpdta)]n·nH2O [Ln=La, 15; Ce, 16; Pr, 17; Nd, 18] were obtained. The two 2D-CPs [Ln(1,3-Hpdta)(H2O)]n·4nH2O (Sm, 19; Eu, 20) were isolated in similar reaction conditions. With the increments of pH value in the solution and reaction temperature, the structure becomes more complicated. 1–5 are soluble in water and 1 was traced by solution 13C{1H} NMR technique, the water-soluble lanthanides 1 and 5 show catalytic activity to ester hydrolysis reaction respectively, which indicate their important roles in the hydrolytic reaction. The europium complexes 13 and 20 show visible fluorescence at an excitation of 394 nm. The structure diversity is mainly caused by the variation of coordinated ligand in different pH values and lanthanide contraction effect. Acidic conditions are favorable for the isolations of lanthanide complexes in different structures and this may helpful to separate different lanthanides. The thermal stability investigations reveal that acidic condition is favorable to obtain the oxides at a lower temperature.

The new semirigid exo-bidentate ligand incorporating furfurysalicylamide terminal groups, namely, 1,4-bis{[(2′-furfurylaminoformyl)phenoxyl]methyl}-2,5-bismethylbenzene (L) was synthesized and used as building blocks for constructing lanthanide coordination polymers with luminescent properties. The series of lanthanide nitrate complexes have been characterized by elemental analysis, IR spectroscopy, and X-ray diffraction analysis. The semirigid ligand L, as a bridging ligand, reacts with lanthanide nitrates forming three distinct structure types: chiral noninterpenetrated two-dimensional (2D) honeycomblike (6,3) (hcb, Schlafli symbol 63, vertex symbol 6 6 6) topological network as type I, 1D zigzag chain as type II and 1D trapezoid ladder-like chain as type III. The structural diversities indicate that lanthanide contraction effect played significant roles in the structural self-assembled process. The luminescent properties of EuIII, TbIII and DyIII complexes are discussed in detail. Due to the good match between the lowest triplet state of the ligand and the resonant energy level of the lanthanide ion, the lanthanide ions in EuIII, TbIII and DyIII complexes can be efficiently sensitized by the ligand.

The X-ray diffraction powder patterns were prepared and the crystal structures were refined for the double-perovskite series of compounds, Sr2RSbO6 (R = Pr, Nd, Sm, Eu, Gd, Dy, Ho, Y, Er, Tm, Yb, and Lu). We found the structures of the entire Sr2RSbO6 series to be monoclinic with space group P21/n (no. 14), and Z = 2. From R = Lu to Pr, the lattice parameters “a” range from 5.7779(2) to 5.879 05(8) Å, “b” range from 5.7888(2) to 5.969 52(9) Å, “c” range from 8.1767(3) to 8.369 20(12) Å, “β” range from 90.112(2)° to 90.313(1)°, and “V” range from 273.483(4) to 293.714(7) Å3. These lattice parameters follow the well-established trend of “lanthanide contraction”. The R3+ and Sb5+ ions are found to be fully ordered in the double-perovskite arrangement of alternating corner-sharing octahedra in a zigzag fashion. The SrO12, RO6, and SbO6 cages are all found to have distorted coordination environments. Powder diffraction patterns of these compounds have been prepared, submitted, and published in the Powder Diffraction File.

The hydrothermal reaction between lanthanide salts and residues of (benzene-1,3,5-triyltris(methylene))triphosphonic acid (H(6)bmt) promotes the formation of a new series of isotypical layered lanthanideorganic frameworks (LnOFs), [Ln(2)(H(3)bmt)(2)]center dot H2O [where Ln(3+) = Eu3+ (1), Gd3+ (2), Tb3+ (3), Dy3+ (4), Ho3+ (5), Er3+ (6), Tm3+ (7), and Yb3+ (8)]. The crystal structure was unveiled from powder X-ray diffraction data (both laboratory and synchrotron) in tandem with other characterization techniques (namely thermogravimetry, thermodiffractometry, vibrational spectroscopy, and elemental analysis). It is shown that the lanthanide contraction leads, on average, to a reduction of the average crystallite size, up to the nanometer scale in the case of compound 8. The unique structural features of the (2)(infinity)[Ln(2)(H(3)bmt)(2)] layers are discussed in detail, in particular, the six-coordination environment of the lanthanide cations and its topological relationship with the formation of the first 5,5L4 binodal network based on chelating phosphonate groups.

Reported are the synthesis and the structural characterization of an extended family of rare-earth metal–germanides with a general formula RE5–xCaxGe3 (RE=Y, Ce–Nd, Sm, Gd–Tm and Lu; x

The 3,5-dichlorobenzoate anion, L–, serves as a bridging ligand and 2,2′-bipyridine, bipy, as a terminal bidentate ligand to yield, through hydrothermal syntheses, the tetranuclear clusters Dy2Co2L10(bipy)2, 1, and Ln2Ni2L10(bipy)2, where Ln is the trivalent La, 2, Gd, 3, Tb, 4, Dy, 5, or Ho, 6, ion. Single-crystal X-ray diffraction reveals that the six complexes are all isomorphous with the monoclinic P21/c space group and with lattice parameters that decrease with the lanthanide contraction. The two cobalt(II) or nickel(II) and two Ln(III) cations are linked by the 10 L– anions to generate Dy2Co2 or Ln2Ni2 3d–4f cationic heteronuclear clusters with a slightly bent Co···Dy···Dy···Co or Ni···Ln···Ln···Ni arrangement. Direct current magnetic susceptibility studies reveal that the complexes are essentially paramagnetic, with room-temperature χMT values close to the expected values for two cobalt(II) or nickel(II) and two Ln(III) cations. The temperature dependence of χMT for 1 and 5 is well reproduced by ab...

Rare earth elements possess 4f orbitals without full electron occupancy and lanthanide contraction. This characteristic results in their unique catalytic performance when they are used as active components or as catalyst supports. Research into and the development of rare earth catalytic materials will significantly promote the high-efficiency utilization of abundant rare earth elements, such as lanthanum and cerium. Currently, rare earth catalytic materials play an important role in such areas as the petroleum chemical industry, the catalytic combustion of fossil fuels, automotive emissions control, the purification of industrial waste air, and solid solution fuel cells. In this paper, we review the application of and recent research progress that has been made on rare earth catalytic materials, including relative theoretical research. The effects of rare earth elements on the structure, activity, and stability of the catalysts of interest are described.

The concept of “slow release anions for the assembly of crystals” was successfully carried out through a facile, effective and environmental friendly supersonic and microwave co-assistance (SMC) approach at very low temperature in less than 40 min. It has been found that the rational design of multiple irradiations, lanthanide contraction and fluoride sources would make it possible to control both the crystalline phases (hexagonal or orthorhombic) and the microstructures (including nanoparticles, nanoplates or micro-meter scale particles). The photo-luminescent properties of EuF 3 and TbF 3 revealed that characteristic red and green emissions can be excited by multiple wavelengths. Moreover, the results demonstrated that there are efficient energy transfers from Gd 3+ to Eu 3+ and Tb 3+ in GdF 3 : Eu 3+ and GdF 3 : Tb 3+ phosphors based on this new method.

A series of 4f-5f heteronuclear metallic complexes were synthesized by a hydrothermal route from mixtures of uranyl acetate, lanthanide nitrate, and 1,2,4,5-benzenetetracarboxylic acid (HBTA) in an aqueous system. Single-crystal X-ray analysis revealed that the thirteen UO-Ln-BTA complexes ([(UO)Ln(COH)(HO)]y HO; Ln=La (1), Ce (2), Pr (3), Nd (4), Sm (5), Eu (6), Gd (7), Tb (8), Dy (9), Ho (10), Er (11), Tm (12), Yb (13); x=6 for 1-4, x=5 for 5-13; y=0 for 4, y=1 for 3, y=2 for 2, y=3 for 5, 9, 10, 12, 13, y=4 for 1, 6, 7, 8, 11) are isomorphous with three-dimensional structures. For the purpose of developing potential applications of the UO-Ln-BTA complexes, we investigated their surface photovoltage and photocatalytic properties. In addition, the thermogravimetric analysis and photoluminescent properties of these complexes were also studied in detail.

Two new non-isostructural lanthanide(III) nitride tellurides with the composition M4N2Te3 bearing terbium (Tb4N2Te3) and dysprosium (Dy4N2Te3) could be synthesized by the reaction of terbium (Tb) or dysprosium (Dy) metal with sodium azide (NaN3), tellurium (Te), iodine (I2), and sodium iodide (NaI) as flux in evacuated silica tubes for seven days at 950 °C. Tb4N2Te3 crystallizes orthorhombically in space group Pnna with the lattice parameters a = 727.14(5), b = 1164.37(8), c = 1100.93(7) pm, Vm = 140.33(2) cm3·mol–1 (Z = 4). In contrast, Dy4N2Te3 appears in the monoclinic space group P21/n with the lattice parameters a = 719.56(5), b = 1164.05(8), c = 1097.34(7) pm, β = 91.327(3)°, Vm = 138.34(2) cm3·mol–1 (Z = 4). Corresponding to the lanthanide contraction the cell parameters of Dy4N2Te3 show slightly smaller values compared to Tb4N2Te3, but the change of symmetry leads to a different crystal system. Symmetry operations related to a and c are lost according to P2/n21/n2/a P121/n1 and the two crystallographically independent M3+ cations in Tb4N2Te3 split into four in Dy4N2Te3. Both Tb3+ cations are coordinated by six anions in first sphere plus one Te2– anion further apart for (Tb1)3+ leading to capped trigonal prisms and distorted octahedra. The four Dy3+ cations with coordination numbers of six plus one and three times six also reside in capped and uncapped distorted octahedral anionic coordination. Both crystal structures have infinite zigzag chains in 1∞{[NM]3+} in common, which are formed by trans-edge connected [NM4]9+ tetrahedra. They run along [010] and exhibit two crystallographically different N3– anions in both cases. The latter are coordinated on the one hand to two sorts of Tb3+ cations in Tb4N2Te3 and on the other hand to four sorts of Dy3+ cations in Dy4N2Te3 as major structural difference. However, both crystal structures show a clear group-subgroup relationship.

Seven lanthanide coordination polymers, namely, {[Ln(BDOA) 1.5 (H 2 O)]·H 2 O} n (Ln = Ce( I ), Pr( II ), Nd( III ), Sm( IV ), Eu( V ), Gd( VI ), and Tb( VII ), H 2 BDOA = benzene-1,4-dioxydiacetic acid), have been synthesized through hydrothermal reactions of lanthanide nitrate with H 2 BDOA ligands and characterized by elemental analysis, infrared spectroscopy and single crystal X-ray diffraction. Findings indicate that I – VI are isomorphous and isostructural, containing the subunit of cavate 10-membered cages (Ln 2 O 2 (OCO) 2 ), while VII possesses the subunit of cavate 14-membered cages (Tb 2 (OCO) 4 ), based on which to assemble into three-dimensional porous architectures via BDOA 2− ligands, hydrogen bonds and C–H⋯π interactions. I and III present antiferromagnetic behaviors and lanthanide contraction effect exists in I – VI . Luminescent studies suggest the typical intense emissions of Ln(III) ions occur in the visible region and therefore the coordination polymers display good selectivity towards some certain metal ions such as Ca 2+ and Cd 2+ , showing promising potential as selective luminescent probes of these metal ions.

A series of RENi9In2 compounds (RE = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho and Er) and their hydrides, RENi9In2Hx (RE = La, Ce, Pr, Nd and Eu), have been synthesized and characterized using X-ray powder diffraction and magnetization measurements. All studied compounds adopt the YNi9In2 structure type [space group (SG) P4/mbm]. The lattice parameters decrease from La to Er in accordance with the lanthanide contraction. Their structure can be visualized as a packing of rare-earth 20-vertices polyhedra and Ni-centred icosahedra in an AuCu-like arrangement. The hydrogenation results in the formation of RENi9In2Hx with slightly expanded unit cells within the YNi9In2 structure type. Possible hydrogen positions in EuNi9In2H3.4 are proposed. Most of the compounds and their hydrides (with Pr and Nd) exhibit Curie–Weiss behaviour. No magnetic ordering could be detected down to T = 2 K. EuNi9In2 reveals ferromagnetism below approximately 40 K, which might be due to a secondary phase. Its hydride is Pauli paramagnetic, thus indicating the Eu3+ state. YNi9In2 and LaNi9In2 are Pauli paramagnets. The studied phases are typical metallic conductors.

The electronic structures of lanthanide (Ln) ions sandwiched between 1,3,5,7-cyclooctatetraene (COT), Ln(COT)2(-), have been investigated by anion photoelectron spectroscopy. Complexes of 12 Ln atoms were investigated (excluding promethium (Pm), europium (Eu), and ytterbium (Yb)). The 213 nm photoelectron (PE) spectra of Ln(COT)2(-) exhibit two peaks assignable to the highest occupied molecular orbital (HOMO; e2u) and the next HOMO (HOMO-1; e2g) approximately at 2.6 and 3.6 eV, respectively, and their energy gap increases as the central metal atom progresses from lanthanum (La) to lutetium (Lu). Since lanthanide contraction shortens the distance between the Ln atom and the COT ligands, the widening energy gap represents the destabilization of the e2u orbital as well as the stabilization of the e2g orbital. Evidence for 4f orbital contribution in the metal-ligand interaction has been revealed by the Ln atom dependence in which the same e2u orbital symmetry enables an interaction between the 4f orbital of Ln atoms and the π orbital of COT.

Solvothermal reactions of lanthanide chloride with a new ligand, H3L, 4′-(3-carboxylpyridyl)-2,2′:6′,2“-terpyridine-6,6”-dicarboxylic acid, yields seven new lanthanide–organic frameworks: {[Ln2L2]⋅H2O}n (Ln=Pr (1), Nd (2), Sm (3), Eu (4)), {[Ln5L4(COO)3(H2O)4]⋅10 H2O}n (Ln=Tb (5), Dy (6)), and [Yb2L2(H2O)2]⋅2 H2O (7). Single-crystal X-ray diffraction reveals that these complexes belong to three structural types. Type I (1–4) consists of lanthanide–carboxyl group layers pillared by L3− to form a three-dimensional network. Type II (5 and 6) comprises a right-handed helical chain and a left-handed helical chain linked through L3− anions into a three-dimensional framework. Type III (7) is a discrete dinuclear structure. The structural change is due to the decrease in the metal coordination number from nine for the large ions to seven for the small ions; this demonstrates the effect of lanthanide contraction. These materials exhibit high thermal stability. In addition, the luminescent properties of these complexes are discussed.

A series of new isomorphic lanthanide-based metal–peptide frameworks, [Ln(PODC)(H2O)2]Br (Ln = La(1), Nd(2), Eu(3), Tb(4), H2PODC = 2, 5-piperazinedione-1, 4-diacetic acid), were synthesized under the ionic liquid medium. Crystal structure measure results exhibit that they are new three-dimensional frameworks, where bromine anions of ionic liquid are enveloped in the pore. Interestingly, it is found that bromine anions can effectively counteract the effects of lanthanide ions (e.g. lanthanide contraction). Via the first-principles DFT calculation, it is obtained that bromine anions of ion liquid influence the electronic properties of PODC2 − ligand and thereby directly control the structure. Luminescence analysis demonstrates that compounds 3 and 4 have good fluorescence properties, where the emission peaks can be ascribed to the transitions of 5D0 → 7FJ (J = 0, 1, 2, 3, 4) for 3 and 5D4 → 7FJ (J = 6, 5, 4, 3) for 4.

The structural and electronic properties of a series of transition metal complexes of bidentate phosphorus ylides, namely [(R 2 P(CH 2 ) n PR 2 C(H)C(O)R)MX 2 ], have been investigated using density functional theory (DFT) calculations at the B3LYP/LanL2DZ level of theory. The substituent R on the phosphorus atoms (R = Me, Ph), metal atoms (M = Ni, Pt, Pd), halogen atoms (X = Cl, Br, I) and (CH 2 ) n groups ( n = 1–3) are combined to make different complexes with five-, six- and seven-membered chelate rings. The results of this work provide valuable guidelines for the synthesis of new bidentate phosphorus ylides and their complexes to be used in industry, catalysis or biological activities. The final geometry of the formed complexes indicates that the X atoms have a cis orientation in five- and six-membered complexes, whilst in seven-membered complexes they have a trans orientation. The general trends of the electronic and structural properties are derived from the free ligands and the corresponding complexes. For all the complexes, the M–P(1) and M–C(2) bonds have the longest bond lengths for Pd(II) complexes, which nicely reflects the Lanthanide contraction. The computed binding energies have shown that a six-membered chelate ring complex, for both the methyl and phenyl substituted ligands, is the most stable form of the n-membered chelate ring complexes. In this regard, the sequence of the binding energies was found as Pt > Pd > Ni; Cl > Br > I; Me > Ph. The results of gap energies indicate that Ni can be considered as the most reactive metal, Ph as the most reactive R group and I as the most reactive halogen. The natural bonding orbital analyses show that the M–P(1) bond has a stronger covalent character than the M–C(2) bond. There is a decrease in the charge distribution on the ligands, reflecting electron transfer from the ligands to the metal and halogen co-ligands so that the M–C bonding orbitals are polarized towards the carbon atom and the M–P bonds are also polarized towards the phosphorus atom. The changing R groups substituted on the phosphorus atom have an effect on the structure and molecular properties of the complexes.