Luminescent single-molecule magnets based on lanthanides: Design strategies, recent advances and magneto-luminescent studies

Lanthanide(III) SMMs with cationic and anionic complex fragments formed by a Schiff base: structure, luminescence, magnetic properties and ab initio calculations

The syntheses, structures, luminescence and magnetic properties of a new series of Ln(III) complexes of the formula [Ln(L)(H2O)2(DMF)2][Ln(L)2] (in which H2L is N,N'-ethylaminebis[1-phenyl-3-methyl-4-formylimino-2-pyrazoline-5-one]; Ln(III) - Gd (1), Tb (2), or Dy (3) ions). The crystal structures were determined by single-crystal X-ray diffraction measurements for all the above-mentioned complexes. The crystals of these compounds consist of cationic [Ln(L)(H2O)2(DMF)2]+ and anionic [Ln(L)2] moieties which form a 3D supramolecular architecture by the H-bonds and electrostatic forces. Luminescence emission in the visible range was observed for Tb(III) and Dy(III) compounds upon ligand sensitization, with moderate quantum yields of 3.2% for the Dy complex and 24.2% for the Tb analogue. Moreover the Tb(III) complex demonstrates triboluminescence activity. The dynamic magnetization studies revealed that 1 and 2 demonstrate field-induced magnetic relaxation with effective energy barriers, ΔE|kB = 24 K (for 1) and 85 K (for 2), while the Dy complex 3 exhibits slow relaxation of magnetization in zero field with an activation energy of 256 K.

Synergism of Light-Induced [4 + 4] Cycloaddition and Electron Transfer Toward Switchable Photoluminescence and Single-Molecule Magnet Behavior in a Dy4 Cubane

Molecular materials possessing switchable magneto-optical properties are of great interest due to their potential applications in spintronics and molecular devices. However, switching their photoluminescence (PL) and single-molecule magnet (SMM) behavior via light-induced structural changes still constitutes a formidable challenge. Here, a series of cubane structures were synthesized via self-assembly of 9-anthracene carboxylic acid (HAC) and rare-earth ions. All complexes exhibited obvious photochromic phenomena and complete PL quenching upon Xe lamp irradiation, which were realized via the synergistic effect of photogenerated radicals and [4 + 4] photocycloaddition of the AC components. The quenched PL showed the largest fluorescence intensity change (99.72%) in electron-transfer photochromic materials. A reversible decoloration process was realized via mechanical grinding, which is unexpectedly in the electron-transfer photochromic materials. Importantly, an SMM behavior of the Dy analog was observed after room-temperature irradiation due to the photocycloaddition of AC ligands and the photogenerated stable radicals changed the electrostatic ligand field and magnetic coupling. Moreover, based on the remarkably photochromic and photoluminescent properties of these compounds, 2 demos were applied to support their application in information anti-counterfeiting and inkless printing. This work, for the first time utilizing the simultaneous modulation of photocycloaddition and photogenerated radicals in one system, realizes complete PL quenching and light-induced SMM behavior, providing a dynamical switch for the construction of multifunctional polymorphic materials with optical response and optical storage devices.

Ferromagnetically Coupled Chromium(III) Dimer Shows Luminescence and Sensitizes Photon Upconversion

There has been much progress on mononuclear chromium(III) complexes featuring luminescence and photoredox activity, but dinuclear chromium(III) complexes have remained underexplored in these contexts until now. We identified a tridentate chelate ligand able to accommodate both meridional and facial coordination of chromium(III), to either access a mono- or a dinuclear chromium(III) complex depending on reaction conditions. This chelate ligand causes tetragonally distorted primary coordination spheres around chromium(III) in both complexes, entailing comparatively short excited-state lifetimes in the range of 400 to 800 ns in solution at room temperature and making photoluminescence essentially oxygen insensitive. The two chromium(III) ions in the dimer experience ferromagnetic exchange interactions that result in a high spin (S=3) ground state with a coupling constant of +9.3 cm-1. Photoinduced energy transfer from the luminescent ferromagnetically coupled dimer to an anthracene derivative results in sensitized triplet-triplet annihilation upconversion. Based on these proof-of-principle studies, dinuclear chromium(III) complexes seem attractive for the development of fundamentally new types of photophysics and photochemistry enabled by magnetic exchange interactions.

Magneto-structural correlation in lanthanide luminescent [2.2]paracyclophane-based single-molecule magnets

The association of lanthanide ions and paracyclophane derivatives has been very scarcely reported in the literature. In this study, elaboration of five coordination lanthanide complexes involving the 1,4(1,4)-dibenzenacyclohexaphane-12,43-diylbis(diphenylphosphine oxide) ligand (L) was achieved with the determination of single-crystal X-ray diffraction structures of four mononuclear complexes of formula [Ln(hfac)3(L)] (hfac- = 1,1,1,5,5,5-hexafluoroacetylacetonate) (Ln = Dy(III) (1-Dy) and Yb(III) (2-Yb)) and [Ln(tta)3(L)] (tta- = 2-tenoyl-trifluoroacetylacetonate) (Ln = Dy(III) (3-Dy) and Yb(III) (4-Yb)) and one dinuclear complex [Na(Dy2(hfac)6(L)2)](BArF) (BArF- = tetrakis[3,5-bis(trifluoromethyl)phenyl]borate) (5-Dy). The compounds were characterized using elemental analysis, IR spectroscopy, DC and AC magnetic measurements and photophysical investigations. L is an efficient organic chromophore for the sensitization of both visible Dy(III) (1-Dy) and near-infrared Yb(III) (2-Yb and 4-Yb) luminescence. The combination of excitation and emission spectra allowed the determination of the crystal field spitting of both the 2F7/2 ground state and 2F5/2 excited state for 2-Yb and 4-Yb. Moreover, 3-Dy and the two Yb(III) derivatives displayed field-induced single-molecule magnet (SMM) behaviour with slow magnetic relaxation occurring through the Raman process only for 2-Yb and 4-Yb, whereas a combination of Orbach and Raman processes was identified for 3-Dy.

Optical Phenomena in Molecule-Based Magnetic Materials

Since the last century, we have witnessed the development of molecular magnetism which deals with magnetic materials based on molecular species, i.e., organic radicals and metal complexes. Among them, the broadest attention was devoted to molecule-based ferro-/ferrimagnets, spin transition materials, including those exploring electron transfer, molecular nanomagnets, such as single-molecule magnets (SMMs), molecular qubits, and stimuli-responsive magnetic materials. Their physical properties open the application horizons in sensors, data storage, spintronics, and quantum computation. It was found that various optical phenomena, such as thermochromism, photoswitching of magnetic and optical characteristics, luminescence, nonlinear optical and chiroptical effects, as well as optical responsivity to external stimuli, can be implemented into molecule-based magnetic materials. Moreover, the fruitful interactions of these optical effects with magnetism in molecule-based materials can provide new physical cross-effects and multifunctionality, enriching the applications in optical, electronic, and magnetic devices. This Review aims to show the scope of optical phenomena generated in molecule-based magnetic materials, including the recent advances in such areas as high-temperature photomagnetism, optical thermometry utilizing SMMs, optical addressability of molecular qubits, magneto-chiral dichroism, and opto-magneto-electric multifunctionality. These findings are discussed in the context of the types of optical phenomena accessible for various classes of molecule-based magnetic materials.

Chiral Heterometallic Cu8Ln4 Complexes with Enantiopure Schiff Base Ligands: Synthesis, Structural, Spectroscopic and Magnetic Studies

The enantiomerically pure Schiff base ligands H2L-S and H2L-R yield chiral heterometallic dodecanuclear complexes of the form [Cu8Ln4(OH)8(OMe)4(O2CBut)8(L-S or L-R)4(H2O)4] where LnIII=Gd (1S), Tb (2S), Dy (3S, 3R), Ho (4S, 4R), Er (5S) or Y (6S, 6R) and H2L=(S or R)-2-{[(1-hydroxypropan-2-yl)imino]methyl}-6-methoxyphenol. The complexes are isomorphous and crystallize in the non-centrosymmetric polar space group C2 in enantiomeric conformation. The chirality of the Schiff base ligands originates from the respective S- or R- enantiomer of 2-aminopropan-1-ol, is imparted to the complexes and to the crystals that belong to non-centrosymmetric space group. The chirality and enantiomeric conformation of all complexes are retained in dmso solutions as confirmed by Circular Dichroism spectra which consist of mirror images, expected for enantiomeric pairs. All complexes consist of four distorted cubane-like subunits [Cu2Ln2(μ3-OH)2(μ3-OMe)(μ3-OR)], which share the LnIII ions and result in a cyclic distorted tetragonal arrangement; each edge of the {LnIII 4} quadrilateral is occupied by two μ-OH- ions that further bridge to a CuII ion. Magnetic susceptibility measurements revealed ferromagnetic interactions for 3S with LnIII=Dy and antiferromagnetic interactions for all other complexes. AC susceptibility data of 3S under 1 kOe external dc field indicate slow magnetic relaxation phenomena below 2 K.

Aggregation induced emission dynamic chiral europium(III) complexes with excellent circularly polarized luminescence and smart sensors

The synthesis of dynamic chiral lanthanide complex emitters has always been difficult. Herein, we report three pairs of dynamic chiral EuIII complex emitters (R/S-Eu-R-1, R = Et/Me; R/S-Eu-Et-2) with aggregation-induced emission. In the molecular state, these EuIII complexes have almost no obvious emission, while in the aggregate state, they greatly enhance the EuIII emission through restriction of intramolecular rotation and restriction of intramolecular vibration. The asymmetry factor and the circularly polarized luminescence brightness are as high as 0.64 (5D0 → 7F1) and 2429 M-1cm-1 of R-Eu-Et-1, achieving a rare double improvement. R-Eu-Et-1/2 exhibit excellent sensing properties for low concentrations of CuII ions, and their detection limits are as low as 2.55 and 4.44 nM, respectively. Dynamic EuIII complexes are constructed by using chiral ligands with rotor structures or vibration units, an approach that opens a door for the construction of dynamic chiral luminescent materials.

Luminescent Er3+ based single molecule magnets with fluorinated alkoxide or aryloxide ligands

We report the synthesis, structures, and magnetic and luminescence properties of a series of new mono- and dinuclear Er3+ complexes derived from sterically demanding aryloxide and fluorinated alkoxide ligands: [4-tBu-2,6-(Ph2CH)2C6H2O]3Er(THF) (1), [(C6F5)3CO]3Er(Me3SiOH) (2), [(C6F5)3CO]3Er[(Me3Si)2NH] (3), [(C6F5)3CO]3Er(C6H5CH3) (4), [(C6F5)3CO]3Er(o-Me2NC6H4CH3) (5) and {[Ph(CF3)2CO]2Er(μ2-OC(CF3)2Ph)}2 (6). In compounds 1, 2, and 4, the Er3+ ion is four-coordinated and adopts a distorted trigonal pyramidal geometry, while in 3, 5, and 6, the coordination geometry of Er3+ is impacted by the presence of several relatively short Er⋯F distances, making them rather 6-coordinated. All compounds behave as field-induced Single Molecule Magnets (SMMs) and exhibit an Er3+ characteristic near infrared (NIR) emission associated with the 4I13/2 → 4I15/2 transition with a remarkably long lifetime going up to 73 μs, which makes them multifunctional luminescent SMMs. The deconvolution of the NIR emission spectra allowed us to provide a direct probe of the crystal field splitting in these compounds, which was correlated with magnetic data.

Different anion (NO3- and OAc-)-controlled construction of dysprosium clusters with different shapes

The complex hydrolysis process and strong uncertainty of self-assembly rules have led to the precise synthesis of lanthanide clusters still being in the "blind-box" stage and simplifying the self-assembly process and developing reliable regulation strategies have attracted widespread attention. Herein, different anions are used to induce the construction of a series of dysprosium clusters with different shapes and connections. When the selected anion is NO3-, it blocks the coordination of metal sites around the cluster through the terminal group coordination mode, thereby controlling the growth of the cluster. When NO3- was changed to OAc-, OAc- adopted a bridging mode to induce modular units to build dysprosium clusters through an annular growth mechanism. Specifically, we selected 2-amino-6-methoxybenzoic acid, 2-hydroxybenzaldehyde, and Dy(NO3)3·6H2O to react under solvothermal conditions to obtain a pentanuclear dysprosium cluster (1). The five Dy(III) ions in 1 are distributed in upper and lower planes and are formed by the tight connection of nitrogen and oxygen atoms, and μ3-OH- bridges on the ligand. Next, octa-nuclear dysprosium cluster (2) were obtained by only regulating ligand substituents. The eight Dy(III) ions in 2 are tightly connected through ligand oxygen atoms, μ2-OH-, and μ3-OH- bridges, forming an elliptical {Dy/O} cluster core. Furthermore, only by changing NO3- to OAc-, a wheel-shaped tetradeca-nuclear dysprosium cluster (3) was obtained. Cluster 3 is composed of OAc- bridged multiple template Dy3L3 units and pulling of these template units connected by an annular growth mechanism forms a wheel-shaped cluster. The angle of the coordination site on NO3- is ∠ONO = 115°, which leads to the further extension of the metal sites on the periphery of clusters 1 and 2 through the terminal group coordination mode, thereby regulating the structural connection of the clusters. However, the angle of the coordination site on OAc- is ∠OCO = 128°, and a slightly increased angle leads to the formation of a ring-shaped cluster 3 by connecting the template units through bridging. This is a rare example of the controllable construction of lanthanide clusters with different shapes induced by the regulation of different anions, which provides a new method for the precise construction of lanthanide clusters with special shapes.

Spectroscopic techniques to probe magnetic anisotropy and spin-phonon coupling in metal complexes

Magnetism of molecular quantum materials such as single-molecule magnets (SMMs) has been actively studied for potential applications in the new generation of high-density data storage using SMMs and quantum information science. Magnetic anisotropy and spin-phonon coupling are two key properties of d- and f-metal complexes. Here, phonons refer to both intermolecular and intramolecular vibrations. Direct determination of magnetic anisotropy and experimental studies of spin-phonon coupling are critical to the understanding of molecular magnetism. This article discusses our recent approach in using three complementary techniques, far-IR and Raman magneto-spectroscopies (FIRMS and RaMS, respectively) and inelastic neutron scatterings (INS), to determine magnetic excited states. Spin-phonon couplings are observed in FIRMS and RaMS. DFT phonon calculations give energies and symmetries of phonons as well as calculated INS spectra which help identify magnetic peaks in experimental INS spectra.

Covalency versus magnetic axiality in Nd molecular magnets: Nd-photoluminescence, strong ligand-field, and unprecedented nephelauxetic effect in fullerenes NdM2N@C80 (M = Sc, Lu, Y)

Nd-based nitride clusterfullerenes NdM2N@C80 with rare-earth metals of different sizes (M = Sc, Y, Lu) were synthesized to elucidate the influence of the cluster composition, shape and internal strain on the structural and magnetic properties. Single crystal X-ray diffraction revealed a very short Nd-N bond length in NdSc2N@C80. For Lu and Y analogs, the further shortening of the Nd-N bond and pyramidalization of the NdM2N cluster are predicted by DFT calculations as a result of the increased cluster size and a strain caused by the limited size of the fullerene cage. The short distance between Nd and nitride ions leads to a very large ligand-field splitting of Nd3+ of 1100-1200 cm-1, while the variation of the NdM2N cluster composition and concomitant internal strain results in the noticeable modulation of the splitting, which could be directly assessed from the well-resolved fine structure in the Nd-based photoluminescence spectra of NdM2N@C80 clusterfullerenes. Photoluminescence measurements also revealed an unprecedentedly strong nephelauxetic effect, pointing to a high degree of covalency. The latter appears detrimental to the magnetic axiality despite the strong ligand field. As a result, the ground magnetic state has considerable transversal components of the pseudospin g-tensor, and the slow magnetic relaxation of NdSc2N@C80 could be observed by AC magnetometry only in the presence of a magnetic field. A combination of the well-resolved magneto-optical states and slow relaxation of magnetization suggests that Nd clusterfullerenes can be useful building blocks for magneto-photonic quantum technologies.

Single-molecule magnet behavior in heterometallic decanuclear [Ln2Fe8] (Ln = Y, Dy, Ho, Tb, Gd) coordination clusters

Five decanuclear lanthanide-iron clusters, formulated as [Ln2Fe8(hmp)10(μ2-OH)4(μ3-OH)2(μ4-O)4(H2O)6]·6ClO4·xH2O (x ≈ 8, Ln = Y for 1; x ≈ 6, Ln = Dy for 2; x ≈ 6, Ln = Ho for 3; x ≈ 7, Ln = Tb for 4; x ≈ 7, Ln = Gd for 5, Hhmp = 2-(hydroxymethyl)pyridine), have been synthesized and structurally characterized. Single-crystal structural analysis reveals that the cluster consists of six face-sharing defective cubane units. Dynamic magnetic investigations indicated that cluster 2 exhibits single-molecule magnet behavior under a zero dc field eliciting an effective energy barrier of Ueff = 17.76 K and a pre-exponential factor of τ0 = 7.93 × 10-8 s. Investigation of the performance of a series of FeIII-DyIII SMMs indicates that the relatively low energy barrier in 2 is associated with the weak ferromagnetic coupling between FeIII and DyIII ions, while the strength of ferromagnetic interaction in these clusters is mainly related to the bond distances between DyIII and O atoms coordinated to FeIII ions. Clusters 3 and 4 exhibit similar dual relaxation pathways under their respective optimal external applied dc field, where the direct relaxation process occurs in the low-frequency area, which impedes the extraction of the Ueff, while the secondary relaxation process appears at a higher frequency, which is probably a connection with intermolecularly driven relaxation. Our findings offer a magneto-structural correlation model for further investigating the single-molecule magnet behavior in lanthanide-iron systems.

Heteroleptic samarium complexes with high quantum yields for temperature sensing applications

Two new crystallographically characterized samarium complexes, [Sm(fod)3(L1)] (1) and [Sm(fod)3(L2)] (2) {L1 = 4,7-diphenyl-1,10-phenanthroline (bath), L2 = 2,2':6',2''-terpyridine and fod = anion of 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedione (Hfod)}, were synthesized and thoroughly characterized. Single-crystal (SC) analysis shows that complex 1 is an eight-coordinate structure with a distorted square antiprism geometry (D4d), whereas complex 2 possesses a nine-coordinate structure with distorted muffin geometry (Cs). The NMR results are in line with SC-XRD analysis, which further validate that the complexes remain intact in solutions. The photophysical characteristics of the complexes were studied in both visible and near infra-red (NIR) regions. The PLQY values of the present complexes were found to be higher than those reported in the literature except for a tetrakis Sm complex. This result indicates that both the ligands act as effective antennas for the present systems. A comparison of PLQY and emission lifetime values within the present complexes (in solid state) reveals that energy transfer from terpy to Sm3+ is more effective than that from the bath ligand. Various color parameters of the complexes were calculated, and the determined CCT values suggest that the complexes may be used as warm light sources. The determined band gap values for the complexes are in the range of those for semiconductors, which suggest the application of present systems in the field of optoelectronics. The curve between the emission intensity and temperature for complex 1 shows a perfect linearity (χ2 = 0.99), which suggests that this complex can have potential application as a temperature sensor in the range 60-350 K.

Influence of symmetry on the magneto-optical properties of a bifunctional macrocyclic DyIII complex

In this work, a novel complex, [Dy(LPr)(NO3)2]·(H2O)·(NO3) (1), containing a highly distorted macrocyclic ligand (LPr) and weak axial anions (NO3-), was synthesized and characterized. Even though this coordination environment is not ideal for maximizing the magnetic anisotropy of a DyIII ion, a magneto-structural analysis reveals that the high distortion of the macrocycle promotes a disposition of the hard plane and easy axis opposite to the expected one. This results in a quite symmetrical environment which allows obtaining a field induced SMM behaviour. The magnetic relaxation properties of this complex were rationalized with the aid of ab initio multireference calculations. Moreover, 1 showed the characteristic emission bands of DyIII ion, indicating that the macrocyclic ligand acts as an efficient sensitizer in the energy transfer process to the emissive state of the DyIII ion. Due to the symmetric environment of 1, the Y/B intensity ratio (0.61) results in CIE coordinates (0.278; 0.314), close to those of the white light region. To gain further insight into the mechanism leading to the luminescence properties, ab initio calculations were performed to elucidate the key factors controlling the Y/B intensity ratio in this bifunctional complex.

Two Stable Bifunctional Zinc Metal-Organic Frameworks with Luminescence Detection of Antibiotics and Proton Conduction

Functionalized crystalline solids based on metal-organic frameworks (MOFs) enable efficient luminescence detection and high proton conductivity, making them crucial in the realms of environmental monitoring and clean energy. Here, two structurally and functionally distinct zinc-based MOFs, [Zn(TTDPa)(bodca)]·H2O (1) and [Zn(TTDPb)(bodca)]·H2O (2), were successfully designed and synthesized using 3,6-di(pyridin-4-yl)thieno[3,2-b]thiophene (TTDPa) and 2,5-di(pyridin-4-yl)thieno[3,2-b]thiophene (TTDPb) as ligands, in the presence of bicyclo[2.2.2]octane-1,4-dicarboxylic acid (H2bodca). Both 1 and 2 display a three-dimensional (3D) structure with 5-fold interpenetration, and notably, 2 forms a larger one-dimensional pore measuring 17.16 × 10.81 Å2 in size. Fluorescence experiments demonstrate that 1 and 2 can function as luminescent sensors for nitrofurantoin (NFT) and nitrofurazone (NFZ) with low detection limits, remarkable selectivity, and good recyclability. A comprehensive analysis was conducted to investigate the differing sensing effects of compounds 1 and 2 and to explore potential sensing mechanisms. Additionally, at 328 K and 98% relative humidity, 1 and 2 exhibit proton conductivity values of 2.13 × 10-3 and 4.91 × 10-3 S cm-1, respectively, making them suitable proton-conducting materials. Hence, the integration of luminescent sensing and proton conductivity in monophasic 3D Zn-MOFs holds significant potential for application in intelligent multitasking devices.

Dipotassiumtetrachloride-bridged dysprosium metallocenes: a single-molecule magnet

The present work describes the dynamic magnetic properties of the complex [(CpAr3)4DyIII2Cl4K2]·3.5(C7H8) (1), synthesized by employing a tri-aryl-substituted cyclopentadienyl ligand (CpAr3), [4,4'-(4-phenylcyclopenta-1,3-diene-1,2-diyl)bis(methylbenzene) = CpAr3H]. Each Dy(III)-metallocene weakly couples via K2Cl4, displaying slow relaxation of magnetization below 14.5 K under zero applied dc field via KD3 energy levels with an energy barrier of 136.9/133.7 cm-1 on the Dy sites. The single-ion axial anisotropy energy barrier is reduced by geometrical distortion due to the coordination of two chloride ions at each Dy centre.

Single molecule magnet features in luminescent lanthanide coordination polymers with heptacoordinate Dy/Yb(III) ions as nodes

Two sets of 1D/2D lanthanide coordination polymers with formulas of Ln(oqa)3·2H2O [Hoqa = 2-(4-oxoquinolin-1(4H)-yl) acetic acid, Ln = Dy (1), Yb (2)] and Ln(oaa)2(HCOO)(H2O) [Hoaa = 2-(9-oxoacridin-10(9H)-yl) acetic acid, Ln = Dy (3), Yb (4)] have been synthesized and their physical properties were investigated. All four complexes are constructed from seven-coordinate lanthanide ions and corresponding organic linkers. The lanthanide ions in 1 and 2 adopt a pentagonal bipyramid coordination geometry, whereas the coordination geometry of lanthanide ions in 3 and 4 can be described as a capped octahedron. Slow magnetic relaxation behaviors were observed in these four products at a zero/non-zero static magnetic field. Complexes 1, 2 and 4 exhibit the characteristic emission of Ln(III) ions, whereas complex 3 shows ligand-based emission. Bright yellow light emission was also observed when a voltage was applied, demonstrating the potential of 1 for application in light-emitting diodes (LEDs). Compounds 3 and 4 are the first examples of lanthanide complexes based on Hoaa ligands.

Tetranuclear lanthanide-based silsesquioxanes: towards a combination of a slow relaxation of the magnetization and a luminescent thermometry

Lanthanide-based silsesquioxanes constitute an emerging family of cage-like metallasilsesquioxanes with exciting optical and magnetic properties. We report here the synthesis, structures and luminescence properties of a series of tetranuclear lanthanide-silsesquioxane compounds of general formula [NEt4]2[(Ph4Si4O8)2(Ln/Ln')4(NO3)6(EtOH)2(MeCN)2]·4(MeCN) with different lanthanide ions (where Ln/Ln' = Dy3+/Eu3+ (1), Dy3+/Tb3+ (2) and Eu3+/Tb3+/Y3+ (3)) and investigate the impact of the lanthanide ions combination on magnetic and photo-luminescent properties. Compound 1 behaves as a field-induced Single Molecule Magnet (SMM) and presents temperature-dependent luminescence characteristics of Eu3+ making it an emissive thermometer working in the temperature range 293-373 K with the maximum relative sensitivity of 1.15% K-1 achieved at 293 K. Compounds 2 and 3 are paramagnets, which demonstrate a characteristic photoluminescence with Dy3+ to Tb3+ and Tb3+ to Eu3+ energy transfers, respectively.

Luminescent Single-Molecule Magnets as Dual Magneto-Optical Molecular Thermometers

Luminescent thermometry allows the remote detection of the temperature and holds great potential in future technological applications in which conventional systems could not operate. Complementary approaches to measuring the temperature aiming to enhance the thermal sensitivity would however represent a decisive step forward. For the first time, we demonstrate the proof-of-concept that luminescence thermometry could be associated with a complementary temperature readout related to a different property. Namely, we propose to take advantage of the temperature dependence of both magnetic (canonical susceptibility and relaxation time) and luminescence features (emission intensity) found in Single-Molecule Magnets (SMM) to develop original dual magneto-optical molecular thermometers to conciliate high-performance SMM and Boltzmann-type luminescence thermometry. We highlight this integrative approach to concurrent luminescent and magnetic thermometry using an air-stable benchmark SMM [Dy(bbpen)Cl] (H2 bbpen=N,N'-bis(2-hydroxybenzyl)-N,N'-bis(2-methylpyridyl)ethyl-enediamine)) exhibiting Dy3+ luminescence. The synergy between multiparametric magneto-optical readouts and multiple linear regression makes possible a 10-fold improvement in the relative thermal sensitivity of the thermometer over the whole temperature range, compared with the values obtained with the single optical or magnetic devices.

Desolvation-Induced Highly Symmetrical Terbium(III) Single-Molecule Magnet Exhibiting Luminescent Self-Monitoring of Temperature

A conjunction of Single-Molecule Magnet (SMM) behavior and luminescence thermometry is an emerging research line aiming at contactless read-out of temperature in future SMM-based devices. The shared working range between slow magnetic relaxation and the thermometric response is typically narrow or absent. We report TbIII -based emissive SMMs formed in a cyanido-bridged framework whose properties are governed by the reversible structural transformation from [TbIII (H2 O)2 ][CoIII (CN)6 ] ⋅ 2.7H2 O (1) to its dehydrated phase, TbIII [CoIII (CN)6 ] (2). The 8-coordinated complexes in 1 show the moderate SMM effect but it is enhanced for trigonal-prismatic TbIII complexes in 2, showing the SMM features up to 42 K. They are governed by the combination of QTM, Raman, and Orbach relaxation with the energy barrier of 594(18) cm-1 (854(26) K), one of the highest among the TbIII -based molecular nanomagnets. Both systems exhibit emission related to the f-f electronic transitions, with the temperature variations resulting in the optical thermometry below 100 K. The dehydration leads to a wide temperature overlap between the SMM behavior and thermometry, from 6 K to 42 K. These functionalities are further enriched after the magnetic dilution. The role of post-synthetic formation of high-symmetry TbIII complexes in achieving the SMM effect and hot-bands-based optical thermometry is discussed.

Mediating Photochemical Reaction Rates at Lewis Acidic Rare Earths by Selective Energy Loss to 4f-Electron States

Manifesting chemical differences in individual rare earth (RE) element complexes is challenging due to the similar sizes of the tripositive cations and the corelike 4f shell. We disclose a new strategy for differentiating between similarly sized Dy³⁺ and Y³⁺ ions through a tailored photochemical reaction of their isostructural complexes in which the f-electron states of Dy³⁺ act as an energy sink. Complexes RE(hfac)₃(NMMO)₂ (RE = Dy (2-Dy) and Y (2-Y), hfac = hexafluoroacetylacetonate, and NMMO = N-methylmorpholine-N-oxide) showed variable rates of oxygen atom transfer (OAT) to triphenylphosphine under ultraviolet (UV) irradiation, as monitored by ¹H and ¹⁹F NMR spectroscopies. Ultrafast transient absorption spectroscopy (TAS) identified the excited state(s) responsible for the photochemical OAT reaction or lack thereof. Competing sensitization pathways leading to excited-state deactivation in 2-Dy through energy transfer to the 4f electron manifold ultimately slows the OAT reaction at this metal cation. The measured rate differences between the open-shell Dy³⁺ and closed-shell Y³⁺ complexes demonstrate that using established principles of 4f ion sensitization may deliver new, selective modalities for differentiating the RE elements that do not depend on cation size.

Circularly polarized luminescence in the one-dimensional assembly of binaphtyl-based Yb(iii) single-molecule magnets

Lanthanide ions have attracted great interest owing to their optical and magnetic properties. Single-molecule magnet (SMM) behavior has been a fascinating science for thirty years. Moreover, chiral lanthanide complexes allow the observation of remarkable circularly polarized luminescence (CPL). However, the combination of both SMM and CPL behaviors in a single molecular system is very rare and deserves attention in the design of multifunctional materials. Four chiral one-dimensional coordination compounds involving 1,1'-Bi-2-naphtol (BINOL)-derived bisphosphate ligands and the Yb(iii) centre were synthesized and characterized by powder and single-crystal X-ray diffraction. All the Yb(iii)-based polymers displayed field-induced SMM behavior with magnetic relaxation occurring by applying Raman processes and near infrared CPL in the solid state.

High-stability spherical lanthanide nanoclusters for magnetic resonance imaging

High-nuclear lanthanide clusters have shown great potential for the administration of high-dose mononuclear gadolinium chelates in magnetic resonance imaging (MRI). The development of high-nuclear lanthanide clusters with excellent solubility and high stability in water or solution has been challenging and is very important for expanding the performance of MRI. We used N-methylbenzimidazole-2-methanol (HL) and LnCl3·6H2O to synthesize two spherical lanthanide clusters, Ln32 (Ln = Ho, Ho32; and Ln = Gd, Gd32), which are highly stable in solution. The 24 ligands L- are all distributed on the periphery of Ln32 and tightly wrap the cluster core, ensuring that the cluster is stable. Notably, Ho32 can remain highly stable when bombarded with different ion source energies in HRESI-MS or immersed in an aqueous solution of different pH values for 24 h. The possible formation mechanism of Ho32 was proposed to be Ho(III), (L)- and H2O → Ho3(L)3/Ho3(L)4 → Ho4(L)4/Ho4(L)5 → Ho6(L)6/Ho6(L)7 → Ho16(L)19 → Ho28(L)15 → Ho32(L)24/Ho32(L)21/Ho32(L)23. To the best of our knowledge, this is the first study of the assembly mechanism of spherical high-nuclear lanthanide clusters. Spherical cluster Gd32, a form of highly aggregated Gd(III), exhibits a high longitudinal relaxation rate (1 T, r1 = 265.87 mM-1·s-1). More notably, compared with the clinically used commercial material Gd-DTPA, Gd32 has a clearer and higher-contrast T1-weighted MRI effect in mice bearing 4T1 tumors. This is the first time that high-nuclear lanthanide clusters with high water stability have been utilized for MRI. High-nuclear Gd clusters containing highly aggregated Gd(III) at the molecular level have higher imaging contrast than traditional Gd chelates; thus, using large doses of traditional gadolinium contrast agents can be avoided.

Magnetic and Luminescent Dual Responses of Photochromic Hexaazamacrocyclic Lanthanide Complexes

Herein, hexaazamacrocyclic ligand L^N6 was employed to construct a series of photochromic rare-earth complexes, [Ln(L^N6)(NO₃)₂](BPh₄) [1-Ln, Ln = Dy, Tb, Eu, Gd, Y; L^N6 = (3E,5E,10E,12E)-3,6,10,13-tetraaza-1,8(2,6)-dipyridinacyclotetradecaphane-3,5,10,12-tetraene]. The behavior of photogenerated radicals of hexaazamacrocyclic ligands was revealed for the first time. Upon 365 nm light irradiation, complexes 1-Ln exhibit photochromic behavior induced by photogenerated radicals according to EPR and UV-vis analyses. Static and dynamic magnetic studies of 1-Dy and irradiated product 1-Dy* indicate weak ferromagnetic interactions among Dy^III ions and photogenerated L^N6 radicals, as well as slow magnetization relaxation behavior under a 2 kOe applied field. Further fitting analyses show that the magnetization relaxation in 1-Dy* is markedly different from 1-Dy. Time-dependent fluorescence measurements reveal the characteristic luminescence quenching dynamics of lanthanide in the photochromic process. Especially for irradiated product 1-Eu*, the luminescence is almost completely quenched within 5 min with a quenching efficiency of 98.4%. The results reported here provide a prospect for the design of radical-induced photochromic lanthanide single-molecule magnets and will promote the further development of multiresponsive photomagnetic materials.

Anion-Manipulated Hydrolysis Process Assembles of Giant High-Nucleation Lanthanide-Oxo Cluster

Widespread concern has been raised over the synthesis of highly nucleated lanthanide clusters with special shapes and/or specific linkages. Construction of lanthanide clusters with specific shapes and/or linkages can be achieved by carefully regulating the hydrolysis of lanthanide metal ions and the resulting hydrolysis products. However, studies on the manipulation of lanthanide-ion hydrolysis to obtain giant lanthanide-oxo clusters have been few. In this study, we obtained a tetraicosa lanthanide cluster (3) by manipulating the hydrolysis of Dy(III) ions using an anion (OAc^-). As far as we know, cluster 3 has the highest nucleation among all lanthanide-oxo clusters reported. In 3, two triangular Dy₃O₄ are oriented in opposite directions to form the central connecting axis Dy₆(OH)₈, which is in turn connected to six Dy₃O₄ that are oriented in different directions. Meanwhile, a sample of a chiral trinuclear dysprosium cluster (1) was obtained in a mixed CH₃OH and CH₃CN solvent and by replacing the anion in the reaction to Cl^- ions. In this cluster, 1,3,4-thiadiazole-2,5-diamine (L²) is free on one side through π···π interactions and is parallel to the o-vanillin (L¹)^- ligand, thus resulting in a triangular arrangement. The arrangement of L² affects the end group coordination in the cluster 1 structure through hydrogen bonding and induces the cluster to exhibit chirality. When the reaction solvent was changed to CH₃OH, a sample of cluster 2, composed of two independent triangular Dy₃ that have different end group arrangements, was obtained. Magnetic analysis showed that clusters 1 and 3 both exhibit distinctive single-molecule magnetic properties under zero-magnetic-field conditions. This study thus provides a method for the creation of chiral high-nucleation clusters from achiral ligands and potentially paves the way for the synthesis of high-nucleation lanthanide clusters with unique forms.

Structure and Properties of Heterometallics Based on Lanthanides and Transition Metals with Methoxy-β-Diketonates

The possibility of obtaining volatile polynuclear heterometallic complexes containing lanthanides and transition metals bound by methoxy-β-diketonates was studied. New compounds were prepared by cocrystallization of monometallic complexes from organic solvents. Ln(tmhd)₃ were used as initial monometallic complexes (Ln = La, Pr, Sm, Gd, Tb, Dy, Lu; tmhd = 2,2,6,6-tetramethylheptane-3,5-dionate) in combination with TML₂ in various ratios (TM = Cu, Co, Ni, Mn; L: L¹ = 1,1,1-trifluoro-5,5-dimethoxypentane-2,4-dionate, L² = 1,1,1-trifluoro-5,5-dimethoxy-hexane-2,4-dionate, L³ = 1,1,1-trifluoro-5-methoxy-5-methylhexane-2,4-dionate). Heterometallic complexes of the composition [(LnL₂tmhd)₂TM(tmhd)₂] were isolated for light lanthanides Ln= La, Pr, Sm, Gd, and L= L¹ or L². By single crystal XRD, it has been established that heterometallic compounds containing La, Pr, Cu, Co, and Ni are isostructural linear coordination polymers of alternating mononuclear transition metal complexes and binuclear heteroleptic lanthanide complexes, connected by donor-acceptor interactions between oxygen atoms of the methoxy groups and transition metal atoms. A comparison of powder XRD patterns has shown that all heterometallic complexes obtained are isostructural. Havier lanthanides Ln = Tb, Dy, Lu did not form heterometallics. Instead, homometallic complexes Ln(L³)₃ were identified for Ln = Dy, Lu as well as for Ln = La. The thermal properties of the complexes were investigated by TG-DTA and vacuum sublimation tests. The heterometallic complexes were found to be not volatile and decomposed under heating to produce inorganic composites of TM oxides and Ln fluorides. In contrast, Ln(L³)₃ is volatile and may be sublimed in a vacuum. Results of magnetic measurements are discussed for several heterometallic and homometallic complexes.

Polymorphism modulates photoluminescence and magnetic dynamics of mononuclear dysprosium-anthracene complexes

Complexes α-Dy(depma)₃Cl₃ (α-DyCl), β-Dy(depma)₃Cl₃ (β-DyCl) and β-Dy(depma)₃Br₃ (β-DyBr) (depma = 9-diethylphosphono-methylanthracene) are reported. α-DyCl and β-DyCl are polymorphs showing distinct magnetic dynamics with energy barriers of 32.3 K and 66.6 K. They also show distinct luminescence properties with emission peaks at 487 nm and 530 nm, respectively.

Insights into the Spin Dynamics of Mononuclear Cerium(III) Single-Molecule Magnets

Four novel Ce^III mononuclear complexes of formulas [Ce(ntfa)₃(MeOH)₂] (1), [Ce(ntfa)₃(5,5'-Me₂bipy)] (2), [Ce(ntfa)₃(terpy)] (3), and [Ce(ntfa)₃(bipy)₂] (4), where ntfa = 4,4,4-trifluoro-1-(naphthalen-2-yl)butane-1,3-dionato, 5,5'-Me₂bipy = 5,5'-dimethyl-2,2'-dipyridyl, terpy = 2,2':6',2″-terpyridine, and bipy = 2,2'-bipyridine, have been synthesized and structurally characterized with Ce^III displaying coordination numbers of 8, 8, 9, and 10, respectively. Magnetic measurements indicate that all the complexes show a field-induced single-ion magnet behavior under a small applied dc field. The magnetic analysis shows the relevance of the different spin relaxation mechanisms in the magnetic relaxation of the Ce^III compounds, with special emphasis on the local-mode process. Multiconfigurational calculations were also performed to get more information on the axiality of the compounds.

Magnetic and Luminescence Properties of 8-Coordinated Pyridyl Adducts of Samarium(III) Complexes Containing 4,4,4-Trifluoro-1-(naphthalen-2-yl)-1,3-butanedionate

A novel series of polypyridyl adducts, [Sm(ntfa)3(NN)] (2–4), with ntfa = 4,4,4-trifluoro-1-(naphthalen-2-yl)-1,3-butanedionate, NN = 2,2′-bipyridine (bipy), 4,4′-dimethyl-2,2′-bipyridine (4,4′-Me2bipy), and 5,5′-dimethyl-2,2′-bipyridine (5,5′-Me2bipy) were synthesized from the precursor complex [Sm(ntfa)3(MeOH)2] (1) and the corresponding pyridyl ligands. Single X-ray crystallography showed that the complexes displayed 8-coordinated geometry. The solid pyridyl adducts 2–4 exhibited emission of luminescence in the NIR and visible regions with close quantum yields (QY = 0.20–0.25%). The magnetic data of 1–4 showed larger values than those expected for magnetically noncoupled Sm(III) complexes in the 6H5/2 ground state, with no saturation on the applied high magnetic field static at a temperature of 2 K.

Single-molecule nano-optoelectronics: insights from physics

Single-molecule optoelectronic devices promise a potential solution for miniaturization and functionalization of silicon-based microelectronic circuits in the future. For decades of its fast development, this field has made significant progress in the synthesis of optoelectronic materials, the fabrication of single-molecule devices and the realization of optoelectronic functions. On the other hand, single-molecule optoelectronic devices offer a reliable platform to investigate the intrinsic physical phenomena and regulation rules of matters at the single-molecule level. To further realize and regulate the optoelectronic functions toward practical applications, it is necessary to clarify the intrinsic physical mechanisms of single-molecule optoelectronic nanodevices. Here, we provide a timely review to survey the physical phenomena and laws involved in single-molecule optoelectronic materials and devices, including charge effects, spin effects, exciton effects, vibronic effects, structural and orbital effects. In particular, we will systematically summarize the basics of molecular optoelectronic materials, and the physical effects and manipulations of single-molecule optoelectronic nanodevices. In addition, fundamentals of single-molecule electronics, which are basic of single-molecule optoelectronics, can also be found in this review. At last, we tend to focus the discussion on the opportunities and challenges arising in the field of single-molecule optoelectronics, and propose further potential breakthroughs.

Oxalate-bridging NdIII-based arsenotungstate with multifunctional NIR-luminescence and magnetic properties

Oxalate bridged Nd-based arsenotungstate, K₁₄Na₆H₄[{(As₂W₁₉O₆₇(H₂O))Nd(H₂O)₂}₂(C₂O₄)]·64H₂O (1), was obtained from the reaction of K₁₄[As₂W₁₉O₆₇(H₂O)], oxalic acid, and NdCl₃·6H₂O in mildly acidic aqueous solution. The polyanion exhibits a dimeric structure in which the fully deprotonated oxalate ligands bridge two Nd^III cations and the arsenotungstate anions act as blocking ligands. The photoluminescence (PL) spectrum of 1 shows the characteristic emission peak of Nd^III in the near-infrared (NIR) region. However, the O → W charge-transfer transitions of arsenotungstate cannot effectively sensitize the emission of Nd^III cations as confirmed by the emission spectrum, due to the mismatch of the energy gap between ³T_1u → ¹A_1g (21.57 × 10³ cm^-1) of arsenotungstate components and ⁴F_3/2 → ⁴I_9/2 (11.43 × 10³ cm^-1) of Nd^III cations. Magnetic studies of 1 demonstrate its field-induced single-molecule magnet (SMM) behavior. Direct current magnetic susceptibility studies imply the weak ferromagnetic couplings present between the two neighboring Nd^III cations. In addition, the synergy between the coordination configuration of Nd^III cations and the intramolecular magnetic interaction was discussed.

Giant Crown-Shaped Dy34 Nanocluster with High Acid-Base Stability Assembled by an out-to-in Growth Mechanism

Lanthanoid metal ions have large ionic radii, complex coordination modes, and easy distortion of coordination spheres, but the design and synthesis of high-nucleation lanthanoid clusters with high stability in solution (especially aqueous solution) are challenging. Herein, a diacylhydrazone ligand (H₂L¹) with multidentate chelating coordination sites was used to react with Dy(OAc)₃·4H₂O under solvothermal conditions to obtain an example of a 34-nucleus crown-shaped dysprosium cluster [Dy₃₄(L)₈(μ₂-OH)(μ₃-OH)₂₁(μ₃-O)₁₄(OAc)₃₁(OCH₃)₂(H₂O)₁₅](OAc)₃ (1). Structural analysis showed that the bisacylhydrazone ligand H₂L¹ with polydentate chelate coordination sites could rapidly capture Dy^III ions, thereby forming 34-nucleus crown-shaped dysprosium cluster 1 following the out-to-in growth mechanism. Cluster 1 remained stable after immersion in solutions with different pH values (3-14) for 24 h. To the best of the authors' knowledge, high-nucleation lanthanoid clusters with excellent strong acid and base stability and water stability are very rare. Meanwhile, high-resolution electrospray mass spectrometry molecular ion peaks produced by cluster 1 were captured, which proved to be stable also in organic solvents. Magnetic research showed that cluster 1 exhibited frequency-dependent behavior. This work provides a new idea for designing and synthesizing high-nucleation lanthanoid clusters with high stability.

Series of the Largest Dish-Shaped Dysprosium Nanoclusters Formed by In Situ Reactions

A three-dimensional supermolecule structure is easily formed due to the diverse coordination modes of high-oxidation-state lanthanide metal ions. However, the design and construction of zero-dimensional (0 D) dish-shaped high-nuclearity lanthanide clusters are difficult. Herein, for the first time, we synthesized a series of the largest dish-shaped high-nuclearity lanthanide nanoclusters (1-4) by in situ tandem reactions under solvothermal one-pot conditions. The formation of 1 and 2 involved an in situ reaction of aldehydes and amines, while the condensation reactions between aldehydes occurred in 3 and 4. Based on the structural characteristics of the dish-shaped lanthanide clusters, we proposed two possible assembly mechanisms involving Dy₁ → Dy₇ → Dy₁₃ → Dy₁₉ (planar epitaxial growth mechanism) and Dy₁ → Dy₁₂ → Dy₁₈ → Dy₁₉ (planar internal growth mechanism).

Dysprosium(III) Metal-Organic Framework Demonstrating Ratiometric Luminescent Detection of pH, Magnetism, and Proton Conduction

A multifunctional metal-organic framework, (Hdmbpy)[Dy(H₂dobdc)₂(H₂O)]·3H₂O (Dy-MOF, H₄dobdc = 2,5-dihydroxyterephthalic acid, dmbpy = 4,4'-dimethyl-2,2'-bipyridine), was synthesized and structurally characterized. The metal center Dy^III is connected by four carboxyl groups to form the [Dy₂(CO₂)₄] binuclear nodes, which are further interconnected by eight separate H₂dobdc^2- ligands to form a three-dimensional (3D) framework including hydrophilic triangular channels and abundant hydrogen-bonding networks. Dy-MOF has good stability in aqueous solution as well as in harsh acidic or alkaline solutions (pH range: 2.0-12.0). Furthermore, the luminescence signal of Dy-MOF undergoes a visualized color change as the acidity of the solution alters, which is the typical behavior of pH ratiometric probe. At a 100% relative humidity, Dy-MOF exhibits a high proton conductivity σ (1.70 × 10^-4 S cm^-1 at 303 K; 1.20 × 10^-3 S cm^-1 at 343 K) based on the proton hopping mechanism, which can be classified as a superionic conductor with σ exceeding 10^-4 S cm^-1. Additionally, the ferromagnetic interaction and magnetic relaxation behavior are simultaneously achieved in Dy-MOF. Herein, the combination of luminescence sensing, magnetism, and proton conduction in a single-phase 3D MOF may offer great potential applications in smart multitasking devices.

Dual-sensitized Eu(III)/Tb(III) complexes exhibiting tunable luminescence emission and their application in cellular-imaging

Two novel dual-photosensitized stable complexes, namely [Eu(dpq)(BTFA)₃] (1) and [Tb(dpq)(BTFA)₃] (2), have been successfully assembled via a mixed ligand approach using dipyrido[3,2-d:2',3'-f]quinoxaline (dpq) and 3-benzoyl-1,1,1-trifluoroacetone (BTFA). The crystallographic data reveal mononuclear lanthanide cores in both 1 and 2, in which each eight-coordinated Ln(III) ion is located in a slightly distorted dodecahedron (D_2d). The room-temperature photoluminescence spectra of complexes 1 and 2 indicate that both BTFA and dpq can effectively sensitize Eu(III) and Tb(III) characteristic luminescence. Moreover, heterometallic Ln-complexes can be synthesized, leading to a new series of differently doped EuxTb1-x complexes. Luminescence experiments on them reveal dual-emission peaks of Eu³⁺ and Tb³⁺, which lead to a gradual change in the luminous colour between yellow-green, yellow, orange, orange-red and red upon increasing the Eu³⁺ content. On the basis of the intrinsic strong emission properties and nontoxic nature of complexes 1 and 2, we explore their potential application as cellular imaging agents. Fluorescence microscopy data suggest the cytosolic and nuclear localization of 1 and 2 in HeLa and MCF-7 cells.

Magnetooptical Properties of Lanthanide(III) Metal-Organic Frameworks Based on an Iridium(III) Metalloligand

Integrating magnetic and optical properties into a metal-organic framework (MOF) remains a great challenge. Herein, we have reasonably constructed two 3D magnetooptical MOFs by incorporating a [Ir^III(ppy)₂(bpy)]⁺-based fluorescent metalloligand and magnetic Ln^III centers. The alternating arrangements of Δ- or Λ-[Ir^III(ppy)₂(bpy)]⁺ endow these MOFs with enhanced optical properties. Moreover, the use of Dy^III leads to field-induced slow magnetic relaxation. This work provides an effective strategy for the preparation of magnetooptical bifunctional MOFs.

Synthesis, Crystal Structures and Magnetic Properties of Trinuclear {Ni2Ln} (LnIII = Dy, Ho) and {Ni2Y} Complexes with Schiff Base Ligands

The reaction of the Schiff base ligand o-OH-C6H4-CH=N-C(CH2OH)3, H4L, with Ni(O2CMe)2∙4H2O and lanthanide nitrate salts in a 4:2:1 ratio lead to the formation of the trinuclear complexes [Ni2Ln(H3L)4(O2CMe)2](NO3) (Ln = Dy (1), Ho (2), and Y (3)) which crystallize in the non-centrosymmetric space group Pna21. The complex cation consists of the three metal ions in an almost linear arrangement. The {Ni2Ln} moieties are bridged through two deprotonated Ophenolato groups from two different ligands. Each terminal NiII ion is bound to two ligands through their Ophenolato, the Nimino atoms and one of the protonated Oalkoxo groups in a distorted octahedral. The central lanthanide ion is coordinated to four Ophenolato oxygen from the four ligands, and four Ocarboxylato atoms from two acetates which are bound in the bidentate chelate mode, and the coordination polyhedron is biaugmented trigonal prism, which probably results in a non-centrosymmetric arrangement of the complexes in the lattice. The magnetic properties of 1–3 were studied and showed that 1 exhibits field induced slow magnetic relaxation.

Assembly of pinwheel/twist-shaped chiral lanthanide clusters with rotor structures by an annular/linear growth mechanism and their magnetic properties

This is the first time that an annular/linear growth mechanism has been proposed for the directional construction of lanthanide clusters with specific shapes.

Single molecule magnet behavior and luminescence of {Ln4} and {LnZn} complexes

A serials of tetranuclear coordination clusters [Ln4L2(HL)2(μ3-OH)2(NO3)2](NO3)2 [Ln = Dy (1•3CH3CN•5H2O), Gd (2•4CH3CN•5H2O), H2L = 6,6'-dimethoxy-2,2'-[2,2-dimethylpropane-1,3-diylbis-(nitrilomethylidyne)] diphenol] and dinuclear complexes [LnZnL(NO3)3(H2O)]•2CH3CN [Ln = Dy (3), Er (4), Yb (5), Lu...

Schiff Base Tetranuclear Zn2Ln2 Single-Molecule Magnets bridged by Hydroxamic acid in association with Near-Infrared Luminescence

A series of Zn-Ln heteronuclear SMMs formed by hexadentate compartment Schiff base Zn-precursor and lanthanoid ions were structurally and magnetically characterized, in which the two [Zn-Ln] moieties are bridged by...