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Summary Single-molecule magnets (SMMs) exhibit magnetization blocking in the presence of strong magnetic anisotropy. By employing molecular engineering, the blocking barrier can be significantly modified, remaining independent from other external factors, such as magnetic field. Taking advantage of hyperfine coupling of electronic and nuclear spins further highlights their unique functionality. However, a poor understanding of relaxation mechanisms limits the exploitation of nuclear-spin molecular qubits. Here, we report the first observation of field-dependent oscillation of the magnetization blocking barrier in a holmium metallacrown magnet driven by the switch of relaxation mechanisms involving hyperfine interaction. First-principles calculations reveal an activated temperature dependence of magnetic relaxation, dominated either by incoherent quantum tunneling of magnetization at anti-crossing points or by Orbach-like processes at crossing points. This mechanism demonstrates that these relaxation barriers can be consecutively switched by increasing the external field, which paves a way for manipulating magnetization dynamics of SMMs using hyperfine interaction.

Controlling molecular magnetic anisotropy via structural engineering is delicate and fascinating, especially for single-molecule magnets (SMMs). Herein a family of dysprosium single-ion magnets (SIMs) sitting in pentagonal bipyramid geometry have been synthesized with the variable-size terminal ligands and counter anions, through which the subtle coordination geometry of Dy(III) can be finely tuned based on the size effect. The effective energy barrier (Ueff) successfully increases from 439 K to 632 K and the magnetic hysteresis temperature (under a 200 Oe/s sweep rate) raises from 11 K to 24 K. Based on the crystal-field theory, a semi-quantitative magneto-structural correlation deducing experimentally for the first time is revealed that the Ueff is linearly proportional to the structural-related value S20 corresponding to the axial coordination bond lengths and the bond angles. Through the evaluation of the remanent magnetization from hysteresis, quantum tunneling of magnetization (QTM) is found to exhibit negative correlation with the structural-related value Stun corresponding to the axial coordination bond angles.

The lead-free double perovskite Cs2AgInCl6 is a potential candidate for LEDs, the photoluminescence performance of which is reinforced greatly by Mn doping. Here, we analyzed the geometric, electronic and photoluminescence properties of Mn-doped Cs2AgInCl6 by means of first-principle calculations. We found that in the interior of Cs2AgInCl6, the Mn dopant formed defect complexes by substituting an Ag atom and generating an Ag vacancy (MnAgVAg) owing to the charge balance and the weak distortion of the metal octahedra. The MnAgVAg defect introduced two defect bands in the forbidden gap, which was contributed predominantly by the 3d orbitals of the Mn2+ ions. The electron transition of the Mn2+ ions from the first excited state to the ground state, i.e., from 4T1 to 6A1 states, gives rise to the PL spectrum that is lower than the bandgap. Therefore, we show that the Mn dopant indeed reinforces the PL performance of Cs2AgInCl6 greatly and is beneficial for its use as an LED material.

The combination of magnetic interaction with high magnetic anisotropy provides a promising way for modulating/fine-tuning molecular magnetic behaviors. Here, we show the building block approach for the synthesis of a family of dilanthanide single-molecule magnets (SMMs) bridged with a cyanometallate starting from a monolanthanide SMM. Contingent on the central para-/diamagnetic [M(CN)

Octahedral CeO2:Er3+ nanocrystals were successfully prepared using a simple hydrothermal method, and the structural and excitation dependent emission properties were investigated in detail. Green (2H11/2, 4S3/2 → 4I15/2), red (4F9/2 → 4I15/2) and NIR (4I11/2 → 4I15/2 and 4I13/2 → 4I15/2) emission were observed under 980 nm laser diode excitation. The optimal Er3+ doping concentration was 3 mol%, and the effect of Li+ co-dopants with concentration up to 10 mol% on microstructure and emission was investigated. However, for the samples excited under 352 nm down-conversion excitation, the Vis-NIR spectral distribution induced distinct changes related to the excitation mode. Remarkably high enhancement of 1532 nm NIR emission about 12 times was achieved by codoping with Li+ ions, which make CeO2:Er3+,Li+ nanocrystal a promising candidate for optical amplifier using broadband UV pumping. The possible mechanism of above up-and down-conversion emission and energy transfer process has also been discussed.

The reactions of chiral ligand (R)/(S)-1,1′-binaphthyl-2,2′-diyl phosphate (R-HL/S-HL) and ErCl3·6H2O afford two pairs of di- and tetranuclear enantiomers [Er2(R/S-L)4(EtOH)6]Cl2·6.5EtOH (R-1, S-1)...

In 2016, our group first reported a single-ion magnet (SIM) [Dy(bbpen)Br] (H2bbpen = N,N′‑bis(2‑hydroxybenzyl)‑N,N′‑bis(2‑methylpyridyl)ethylenediamine) with the highest effective energy barrier (Ueff) over 1000 K. To explore further for the high performance single-ion magnets (SIMs), we used functional ligand to replace the Br− anion. The H2bbpen and 4′‑(1,2,2‑triphenylvinyl)benzoic acid (tpe-COOH) ligand with aggregation-induced-emission-active (AIE) property, formed a triangular dodecahedral SIM, [Dy(bbpen)(tpe-COOH)]⋅2MeOH. The structural, magnetic and luminescent properties of the SIM have been investigated. Related to its lower local symmetry around Dy(III) ion, the Ueff was sharply reduced to 77 K under an external dc field of 0.15 T. Therefore, it proved the importance of local symmetry to get the high performance SIMs from the opposite side.

This study reports the first modulation of spin-crossover (SCO) behavior via a photochemical [2 + 2] cycloaddition reaction. Here we construct two no-solvent Fe(II)–Ag(I) bimetallic Hofmann-type frameworks, [Fe(4-spy)2{Ag(CN)2}2] (1) and [Fe(2,4-bpe)2{Ag(CN)2}2] (2) (4-spy = 4-styrylpyridine, 2,4-bpe = trans-1-(2-pyridyl)-2-(4-pyridyl)ethylene). For 1, the dimerization of 4-spy results in a single-crystal to single-crystal (SCSC) transformation from 2D interdigitated layers to a 3D interpenetrated structure. Additionally, a 3D → 3D structural transformation accompanied with Ag(I)–N bond breaking is achieved via the photochemical cycloaddition reaction of 2,4-bpe in 2. More importantly, both the spin transition temperatures and the SCO character are effectively modulated; thus, this approach provides a new strategy for constructing photo-responsive SCO magnetic materials.

Incorporation of two characters into one molecular entity is an effective way to afford bifunctional molecule-based materials. Lanthanides serve as a group of preferable objectives for the construction of luminescent single-molecule magnets (SMMs) due to their excellent performances in areas of SMM and luminescence for molecular materials, showing a great potential of applications in high-density data storage, quantum computing, light-emitting diodes, biofluorescence labelling, etc. This review concentrates on the design strategies for the construction of luminescent SMMs referring to the organic chromophores and transition metal-containing chromophores as the antennas, as well as the recent examples of luminescent SMMs. To investigate the magneto-luminescent behavior (including the magneto-luminescent coupling), a few of classical complexes are discussed in the review to emphasize the importance of studying the correlation/coupling between relaxation mechanism and luminescence for lanthanide SMMs.

Breaking through the nitrogen ceiling Single-molecule magnets could prove useful in miniaturizing a wide variety of devices. However, their application has been severely hindered by the need to cool them to extremely low temperature using liquid helium. Guo et al. now report a dysprosium compound that manifests magnetic hysteresis at temperatures up to 80 kelvin. The principles applied to tuning the ligands in this complex could point the way toward future architectures with even higher temperature performance. Science , this issue p. 1400

Single-molecule magnets (SMMs) are regarded as promising candidates for ultrahigh-density storage, quantum information processing and molecular spintronics. It is a crucial challenge for chemists to modulate magnetic dynamics of SMMs. Here, we successfully synthesized two 3d-4f polynuclear compounds [Co2Dy(TTTTCl)2(MeOH)]NO3·3MeOH (1) and [Co2Dy(TTTTCl)2 (MeOH)][Co(HTTTTCl)](NO3)2·2.5MeOH·2H2O (2), where H3TTTTCl=2,2′,2′′-(((nitrilotris(ethane-2,1-diyl)) tris(azanediyl)) tris(methylene))tris-(4-chlorophenol). On applying the approach by co-crystallization of bulky diamagnetic moiety, the effective energy barrier enhances from 401 K (1) to 536 K (2), which are both among the highest d-f heterometallic SMMs.

A new Hofmann-type porous coordination polymer [Fe(dpni){Ag(CN)2}2]·4CH3CN (dpni = N,N′-di-(4-pyridyl)-1,4,5,8-naphthalenetetracarboxydiimide) with the topology of pcu net has been synthesized. It exhibits two-step spin-crossover behavior. Moreover, reversible changes between incomplete and two-step spin-crossover properties were associated with the desorption/resorption of the CH3CN solvent molecules.

Two structurally intriguing dysprosium(III)-substituted polyoxometalates, [Dy6(ampH)4(H2O)23(ampH2)(PW11O39)2] (1) and [Dy9(CO3)3(ampH)2(H2O)12(PW10O37)6]35– (2), are assembled by the same precursor under different pH conditions. The structure of 1 contains an octahedral {Dy6(ampH)4} core, and a unique windmill-type {Dy9(CO3)3(ampH)2} for 2. Single-molecule magnet behavior is observed for 2 with a thermally activated energy barrier of 56 K and no appreciable quantum tunneling of magnetization under zero field.

Here, we choose (C4H9NH3)2PbI4 to represent the two-dimensional layered hybrid organic–inorganic perovskites and investigate its excellent moisture resistance by theoretical analyses. (C4H9NH3)2PbI4 adsorbs H2O molecules easily on all surfaces. However, the most energetic surface, i.e., C4H9NH3-terminated surface, provides an energy barrier of 3.46 eV to prevent the penetration of H2O molecules, which is 1 order higher than the barrier in MAPbI3 surface. This obstacle for the invasive H2O molecule comes from the methyl/methylene radicals of C4H9NH3 groups. These methyl/methylene radicals are chemically inactive and only generate repulsive interactions with the H2O molecule, leading to the outstanding moisture resistance of (C4H9NH3)2PbI4. Herein, we propose a practical strategy to obtain good moisture-resistant perovskite solar cell materials, i.e., modulate the shape and symmetry of organic molecules in perovskites to let as many methyl radicals as possible prevent the penetration of adsorbed H2O molecul...

Magnetic cooling is a highly efficient refrigeration technique with the potential of replacing expensive and rare helium-3 in the field of ultra-low temperature cooling. However, the visualization of a cryogen at an extremely low temperature and in a strong magnetic field is challenging, but it is crucial for the precise positioning and in situ thermal probe measurements in potential practical applications. Here, the activation of a red-emissive Mn(ii) ion using 3d/4f chemistry produces a luminescent molecule cooler, [Gd5Mn2(LOMe)2(OH)4(Ac)6(MeOH)10Cl2]Cl3·2MeOH (1), with the core of an Mn(ii)-anchored heptanuclear [GdIII5MnII2] pyramid. The photoluminescence (PL) of the Mn2+ emission, with a large Stokes shift (λem ∼ 690 nm) from 4T1(4G) → 6A1(6S), shows not only a sensitive temperature sensing property but also reversible mechanoluminescence (ML). More attractively, these findings reveal a considerable magnetocaloric effect (MCE) coupled with a tunable emission window, opening up new opportunities in the multifunctional applications of PL, ML, and the MCE involving red-light sources, thermometers, and stress imaging. In particular, this provides a novel resolution to design visualized PL coolers.

A 4-amino-1,2,4-triazole (NH2-trz) based linear trinuclear Fe(II) complex of [Fe3(NH2-trz)6(SCN)4(H2O)2](SCN)2·H2O (1) has been hydrothermally synthesized by the reaction of a NH2-trz ligand with FeSO4. A single crystal of complex 1 is able to extrude one lattice water and one coordinated water, leading to another single crystal of complex 1a with a formula [Fe3(NH2-trz)6(SCN)5(H2O)](SCN) by heating. Complex 1a can be reversed to 1 upon the reabsorption of water. Single-crystal X-ray diffraction analysis reveals that these two complexes consist of a linear trinuclear core where a central Fe1 ion is coordinated to six nitrogen atoms from six bridged NH2-trz ligands and one of the terminal Fe2 ions is coordinated to five nitrogen atoms and one oxygen atom. The terminal Fe3 ion in 1 coordinates to five nitrogen atoms and one oxygen atom; however, the terminal Fe3 ion in 1a coordinates to six nitrogen atoms. Magnetic susceptibility measurements demonstrate that they exhibited gradual spin crossover (SCO) for the central Fe(II) ion; however, different spin transition temperatures were displayed for complexes 1 and 1a (T1/2 = 202 K for 1 and 160 K for 1a). These different spin transition temperatures arise from the different intermolecular hydrogen bonding interactions in the two complexes.

Toward promising candidates of quantum information processing, the rapid development of lanthanide-based single-molecule magnets (Ln-SMMs) highlights design strategies in consideration of the local symmetry of lanthanide ions. In this review, crystal-field theory is employed to demonstrate the electronic structures according to the semiquantitative electrostatic model. Then, specific symmetry elements are analysed for the elimination of transverse crystal fields and quantum tunnelling of magnetization (QTM). In this way, high-performance Ln-SMMs can be designed to enable extremely slow relaxation of magnetization, namely magnetic blocking; however, their practical magnetic characterization becomes increasingly challenging. Therefore, we will attempt to interpret the experimental behaviours and clarify some issues in detail. Finally, representative Ln-SMMs with specific local symmetries are summarized in combination with the discussion on the symmetry strategies, and some of the underlying questions are put forward.

Chiral binaphthyl substituents were incorporated onto the phthalocyanine periphery in both homoleptic and heteroleptic bis(phthalocyaninato) terbium single-ion magnets, which exhibit blocking temperatures as high as 15 K and 28 K, respectively, providing an alternative method towards enhancing the magnetic behavior.

The inverse magnetocaloric effect (IMCE) in molecular solids is explored for two antiferromagnetically coupled MnII dinuclear complexes. Magnetic studies reveal that both of them demonstrate the IMCE with negative magnetic entropy changes (−ΔSM = −3.5 J kg–1 K–1), which are in line with an analytic function derived from the quantized phenomenological model proposed in this work.

Motivated by extensive investigations on the In2O3-based multicomponent transparent conducting oxides (TCOs), we want to know the carrier transport properties in these systems and how they evolve with adjusting of geometric structure and constituent elements. Guided by the empirical minimum effective mass physics, we select nine impurities M (M = Sn, Zn, Cd, Hg, Mn, Ni, Co, Ga and Ge) to tune the effective mass (m∗) of In2O3-based TCOs. By means of systematic theoretical investigations, we find that in impurity M isolated or corporately doped In2O3 materials, the substitutional position for dopant M is determined by the charge state. Codoping Sn and other eight impurities into In2O3 (to form IMTO) is an effective strategy to reduce the indium content in In2O3-based TCOs materials. For the recognized n-type carrier contributor, namely, VO defect, it induce spatial localization and orbital localization effects in electronic structures and thus enlarge m∗, which are caused by the large lattice distortion and complicated orbital wavefunction hybridizations. However, for IMTO:VO (M = Zn, Ga and Hg) systems, both localization effects are weakened, leading to a decrease of m∗. It even reduces by half value for In-Hg-Sn-O:VO systems. This systematic work in In2O3-based materials may be helpful in designing of a new range of high performance TCOs.

The dimeric molecule [Dy-2(acac)(6)(MeOH)(2)(bpe)]center dot bpe center dot 2MeOH (1, acac = acetyl-acetonate, bpe = 1,2-bis(4-pyridyl)ethylene) undergoes a solidstate ligand substitution reaction upon heating, leading to the one-dimensional chain [Dy(acac)(3)(bpe)(n) (2). This structural transformation takes advantage of the potential coordination of the guest bpe molecules present in 1. In both complexes the Dy(III) ions adopt similar octatoordinated D-4d geometries, However, the different arrangement of the negatively charged and neutral ligands alters the direction of magnetic anisotropy axis and the energy states, thus resulting in largely distinct magnetization dynamics, as revealed by the CASSCF/RASSI calculations.

ion of a chloride ligand from the dysprosium metallocene [(Cpttt)2DyCl] (1Dy Cpttt=1,2,4‐tri(tert‐butyl)cyclopentadienide) by the triethylsilylium cation produces the first base‐free rare‐earth metallocenium cation [(Cpttt)2Dy]+ (2Dy) as a salt of the non‐coordinating [B(C6F5)4]− anion. Magnetic measurements reveal that [2Dy][B(C6F5)4] is an SMM with a record anisotropy barrier up to 1277 cm−1 (1837 K) in zero field and a record magnetic blocking temperature of 60 K, including hysteresis with coercivity. The exceptional magnetic axiality of 2Dy is further highlighted by computational studies, which reveal this system to be the first lanthanide SMM in which all low‐lying Kramers doublets correspond to a well‐defined MJ value, with no significant mixing even in the higher doublets. peerReviewed

A bifunctional dysprosium(III) dimer, [Dy2(HTPEIPOMe)2(OAc)4(NO3)2] (1), comprising an AIE-active (AIE = aggregation-induced emission) ligand of 2-methoxy-6-[[[4-(1,2,2-triphenylvinyl)phenyl]imino]methyl]phenol (HTPEIPOMe), was successfully synthesized. It not only behaves as a single-molecule magnet (SMM) with an energy barrier of 168(15) K at zero field but also exhibits piezochromism during the pressing–fuming cycle with switchable color, photoluminescence, and magnetic response.

The incorporation of spin-crossover (SCO) properties into metal-organic frameworks (MOFs) is an appealing subclass of multifunctional MOFs with potential applications in molecular sensing. This review focuses on the design of SCO Hofmann-type MOFs, with emphasis on the guest effect on their SCO properties. The influences of guest size, dielectric constant, π⋯π interaction, hydrogen bonding interactions, weak X⋯M′ covalent bonding, and chemical reaction on the SCO properties of Hofmann-type MOFs are systematically explored. Further enhancements of sensing properties are also illustrated.

A dinuclear complex (HNEt3)[Dy2(MQ)4(NO3)3]·EtOH·H2O (HMQ = 2-methyl-8-hydroxyquinoline) was prepared and proved to have no observable single-molecule magnet (SMM) behaviour. With increasing NEt3 in the reaction, two coordinated NO3− units in the {(NO3)3} pocket were replaced by an additional “magnetic motif” [Dy(MQ)4]−. In this way, the unfavourable interactions between the two dysprosiums were diminished and a trinuclear complex [Dy3(MQ)8(NO3)] was obtained, which behaves as an SMM with an efficient energy barrier of 244(21) K for the full temperature range and 150(12) K for the high-temperature region. It is suggested that introduction of a “magnetic motif” is a feasible strategy for modulating the magnetic behaviour of polynuclear systems.

Two dysprosium aggregates, formulated as [Dy2(μ-OH)2(H2bpte)2Cl2(MeOH)2]Cl2 (1), and [Dy8(μ-OH)8(bpte)8]·24H2O (2) (H2bpte = 1,2-bis(3-(pyridin-2-yl)-1H-1,2,4-triazol-5-yl)ethane), were obtained using solvothermal reactions. Upon changing the metal salt and synthetic reaction conditions, an eight-member {Dy8} (2) ring was isolated. Complex 1 is centrosymmetric in which two {Dy2} clusters are connecting to each other through the hydrogen bonding. Complex 2 forms an eight-member DyIII ring with an inner diameter of 4.5 A and is the first reported {Dy8(μ-OH)8} core in lanthanide-hydroxo clusters. The H2bpte ligand displays trans,trans- and cis,cis-coordination modes in 1 and 2, respectively. Alternating current (ac) magnetic measurements of both complexes were carried out. In 1, the out-of-phase susceptibilities (χ''M) below 9 K confirm the slow relaxation of magnetization, which is a typical characteristic of single-molecule magnets (SMMs).

A new mixed valence antiferromagnetic Co7 disc characterized by spectral, crystallographic and magnetic studies exhibited a solvent dependent catecholase activity with Kcat(MeOH) = 2026 h−1. This report demonstrates the first example of a discrete heptanuclear disc showing solvent dependent catecholase activity.

Few spin-crossover materials with a 1D ladder-type structure have been reported. Previously, [Fe(Mebpt){Au(CN)2}]·H2O (MebptH = 3-(5-methyl-2-pyridyl)-5-(2-pyridyl)-1,2,4-triazole) was made and shown to display gradual spin-crossover behaviour. In the current work, a new 1D iron(II) ladder-type compound, [Fe(bpt){Au(CN)2}] (bptH = 3-(2-pyridyl)-5-(2-pyridyl)-1,2,4-triazole), was produced and showed enhanced spin-crossover behavior. It showed an abrupt spin transition above room temperature with a 3 K hysteresis (T1/2↓ = 335 K and T1/2↑ = 338 K). The origin of its enhanced spin-crossover could be ascribed to a greater influence of supramolecular interactions over the electronic substituent effect.

Reversible crystal-to-crystal transformation between a linear trinuclear Fe(II) complex [Fe3(NH2-trz)6(SCN)5(H2O)] (SCN)·4H2O (1, NH2-trz = 4-amino-1,2,4-triazole) and a 1D chain [Fe3(NH2-trz)6(SCN)5]n(SCN)n (1a) and the SCO behaviour change have been studied by X-ray single-crystal diffraction, magnetic measurements and DSC. Complex 1a exhibits one more SCO step at a low temperature.

A wheel-shaped Dy(III) single-molecule magnet (SMM), supported by polyoxotungstates, Cs15K8Na12[K⊂{(AsW9O33)Dy(H2O)2}6]·71H2O (1), is described here. The polyanion of 1 possesses an idealized S6 symmetry. The effective energy barrier (68 K) obtained from magnetic studies is consistent with the deconvolution of the luminescence spectra of 1.

A 3d-4f heterometallic metallacrown with formula of [EuCu5(quinha)5(sal)2(py)5]CF3SO3·py·3H2O (1) (H2quinha = quinaldichydroxamic acid; Hsal = salicylaldehyde) has been synthesized. This complex shows field-induced slow magnetic relaxation via a Raman-like process, where studies of the isostructural {LuCu5} (2) and {YCu5} (3) complexes show that the slow dynamics mainly arise from the {Cu5} S = 1/2 ground state rather than the EuIII ion. However, the EuIII ion enhances the relaxation rates of the {Cu5} unit which likely arises from second-order effects in the formally diamagnetic 7F0 ground state of EuIII.

ion of iodide from [(η5 -C5 i Pr5 )2 UI] (1) produced the cationic uranium(III) metallocene [(η5 -C5 i Pr5 )2 U]+ (2) as a salt of [B(C6 F5 )4 ]- . The structure of 2 consists of unsymmetrically bonded cyclopentadienyl ligands and a bending angle of 167.82° at uranium. Analysis of the bonding in 2 showed that the uranium 5f orbitals are strongly split and mixed with the ligand orbitals, thus leading to non-negligible covalent contributions to the bonding. Investigation of the dynamic magnetic properties of 2 revealed that the 5f covalency leads to partially quenched anisotropy and fast magnetic relaxation in zero applied magnetic field. Application of a magnetic field leads to dominant relaxation by a Raman process.

A family of dinuclear dysprosium cores bridged by different ligands within a polyoxometalates (POMs) framework, (TBA)8.5H1.5[(PW11O39)2Dy2X2(H2O)2]·6H2O (X = OH (1), F (2), OAc (3); TBA = tetra- n-butylammonium), was successfully synthesized and structurally characterized. Magnetic studies indicate that the bridging ligands can significantly affect the magnetic behaviors, with 1 and 3 showing antiferromagnetic coupling and 2 bridged by fluoride ions showing ferromagnetic interaction. 1 and 2 behaved as single-molecule magnets (SMMs) with the thermally activated energy barrier of 98(5) and 74(6) cm-1 under zero dc filed, respectively, whereas no SMM behavior was observed for 3 bridged by two μ-η1:η2-acetato ligands. Notably, the low-temperature fluorescence spectra of 1-3 provide valuable information on the energy levels, which are consistent with the anisotropic barriers determined by magnetic measurements. These results offer an insight into the magneto-optical correlation. Furthermore, the effective energy barrier of 1 reaches a breakthrough among all POM-based SMMs.

A novel 1D lead(II) coordination polymer containing anthracene chromophore through the employment of hydrothermal techniques by using 9-anthracenecarboxylic acid and PbI 2 , [Pb(9-aca) 2 (H 2 O) 2 ] ( 1 ) (9-acaH = 9-anthracenecarboxylic acid) has been synthesized and structurally characterized by X-ray single-crystal diffraction as well as by powder X-ray diffraction and elemental analysis. In compound 1 , each PbO 8 polyhedron is linked to each other by oxygen atoms from 9-acaH ligand to form a 1D molecular nanowire with a diameter of 1.22 nm. Surface photovoltage spectroscopy (SPS) and field-induced surface photovoltage (FISPS) of compound 1 indicate that it possesses positive SPV response in the range of 300–800 nm and shows p -type semiconductor characteristic. Luminescent properties of compound 1 reveal that the compound exhibit strong luminescence, ascribed to the charge transfer of anthracene chromophore and the semiconductor 1D Pb 2 O 2 chain.

The first spin-crossover cluster helicate [{Fe(II)(μ-bpt)3}2Fe(II)3(μ3-O)][Fe(II)2(μ-Cl)(μ-bpt)(NCS)4(H2O)]·2H2O·C2H5OH [Hbpt = 3,5-bis(pyridin-2-yl)-1,2,4-triazole] was reported, in which one spin-crossover unit and one low-spin triple-stranded [Fe(II)(bpt)3](-) unit wrapped a rare planar [Fe(II)3(μ3-O)](4+) core to form a bis(triple-helical) cation with trigonal-bipyramidal topology. The origin of different magnetic behaviors of two [Fe(II)(bpt)3](-) units could be ascribed to their different intermolecular interactions.

The area of molecular magnetic coolants has developed rapidly in recent years. A large number of competitive candidates have been reported, with the cooling performances chasing each other. In this account, four explicit strategies, namely, increasing ground-state spin, reducing magnetic anisotropy, weakening magnetic interactions, and lowering the molecular weight, are proposed from the theoretical viewpoint towards improving the magnetocaloric effect (MCE). According to this guidance, these successful strategies are discussed to pursue excellent magnetic coolants. This is accompanied by a discussion of the representative examples reported by our group. The magnetic entropy change increases from one compound to another, which in the most pronounced cases is suggestive of being the largest MCE in magnetic coolants.

Single-molecule magnets (SMMs) that can be trapped in one of the bistable magnetic states separated by an energy barrier are among the most promising candidates for high-density information storage, quantum processing, and spintronics. To date, a considerable series of achievements have been made. However, the presence of fast quantum tunnelling of magnetization (QTM) in most SMMs, especially in single-ion magnets (SIMs), provides a rapid relaxation route and often sets up a limit for the relaxation time. Here, we pursue the pentagonal bipyramidal symmetry to suppress the QTM and present pentagonal bipyramidal Dy(III) SIMs [Dy(Cy3PO)2(H2O)5]Cl3·(Cy3PO)·H2O·EtOH (1) and [Dy(Cy3PO)2(H2O)5]Br3·2(Cy3PO)·2H2O·2EtOH (2), (Cy3PO = tricyclohexyl phosphine oxide). Magnetic characterizations reveal their fascinating SMM properties with high energy barriers as 472(7) K for 1 and 543(2) K for 2, along with a record magnetic hysteresis temperature up to 20 K for 2. These results, combined with the ab initio calculations, offer an illuminating insight into the vast possibility and potential of what the symmetry rules can achieve in molecular magnetism.

To investigate the effects on the physical properties of complexes with different conformations of flexible ligands, four lanthanide (Ln) coordination polymers with flexible ligand cyclohexane-1e,2a,4a,5e-tetracarboxylic acid (H4LI), [Ln(HLII)(H2O)2]·1.5H2O (Ln = Dy, 1; Tb, 2) and [Ln2(H2LIV)(LIV)(H2O)4]·1.5H2O (Ln = Dy, 3; Tb, 4), have been synthesized and characterized. Complexes 1 and 2 are 2D layers composed of LII ligands and [Ln2O2] dinuclear units whereas complexes 3 and 4 are 3D coordination frameworks constructed with LIV ligands and two kinds of dinuclear units, [Ln2O2] and [Ln2(COO)2]. Notably, the conformations of ligands in two structures, which were different and changed from the original LI conformation to LII (e,a,e,e) and LIV (e,e,e,e) conformations, impact the construction of different structures and the magnetic properties. Complex 1 shows antiferromagnetic interactions whereas complex 3 exhibits weak ferromagnetic interactions and slow magnetic relaxation properties. Additionally, the ...

Aqueous solutions of zirconium oxychloride and aluminum nitrate were coprecipitated and crystallized to form a ZrO2-Al2O3 solid solution. The upconversion (UC) emission from different Er(3+)-doped samples was studied. An enhancement of the green UC emission by as much as 22 times was achieved by co-doping with Yb(3+) and Mo(6+) ions due to an energy transfer at a higher excited-state energy, which partly avoided the non-radiative decay processes at the lower energy levels of Er(3+). The UC emission of the ZrO2-Al2O3 composite system series doped with different agents was enhanced. Excess oxygen vacancies are generated by forming ZrO2-Al2O3 solid solutions, which have an energy level close to the (4)F7/2 level of the Er(3+) ions. The defect state promoted the energy transfer process resulting in an eight-fold increased green UC emission in ZrO2-Al2O3 solid solutions. The solid solutions have a superior color chromaticity of x = 0.25 and y = 0.71 due to the evident enhancement in the green to red emission ratio in the 8ZrO2-2Al2O3 sample.

Two different 3D coordination polymers, [Gd(glc)(Hglc)(H2O)]n·nH2O (1) and [Gd(Hglc)3]n (2) (H2glc = glycolic acid), have been prepared based on the reaction of Gd(III) ions with H2glc in different pH environments. Due to the deprotonation of the α-OH groups from half of the H2glc ligands in 1, [Gd2] units with a Gd–O–Gd bridging model are observed and suggest a stronger magnetic coupling than that in 2. Magnetic and heat capacity studies reveal the significant impact of the strength of magnetic coupling on the magneto-caloric effect (MCE) in systems. Although a theoretical calculation suggests the −ΔSm (50.5 J kg−1 K−1) of 1 is larger than 2 (45.2 J kg−1 K−1), the stronger antiferromagnetic coupling in 1 decreases the number of low-lying excited spin states upon the lowering of temperature, thus giving a smaller value of −ΔSm than 2 at various fields (e.g. −ΔSm,max = 24.8 J kg−1 K−1 and 41.1 J kg−1 K−1 for 1 and 2 respectively at ΔH = 3 T). This case reveals that the effect of magnetic coupling on MCE plays a dominant role for designing low-temperature 3D Gd(III)-based magnetic coolants.

Reaction of copper(II) nitrate trihydrate with N,N-dimethylethanolamine (dmea) and pivalic acid in methanol led to the hexanuclear copper(II) complex Cu6(η1:μ2-C4H10NO)4(η1:η1:μ2-C5H9O2)4(η1:μ1-C5H9O2)2(μ3-OH)2 (1). The crystal structure of 1 indicates that hexametallic centers are bridged by the μ3-alkoxo, dmea oxygens, and the μ2-dicarboxylato oxygen atoms of pivalate ions. Furthermore, in the asymmetric unit, three types of copper ions have been found labeled as Cu1, Cu2 and Cu3. The Cu2 takes a distorted octahedral shape, whereas Cu1 and Cu3 adopt square pyramidal geometries. The complex 1 shows strong antiferromagnetic interactions through the oxo groups within the dimeric units (J = − 82.6 to − 25.8 cm− 1) and weak antiferromagnetic couplings between the dimers (J = − 10.9 and 0.8 cm− 1).

In this work, a novel strategy is designed with the goal of further improving comprehensive performance of anion exchange membrane (AEM). That is, some double-functional monomers with both anion exchange groups and unsaturated double bond pendants, such as N, N-Dimethylallylamine (DMAA), N-Allylmethylamine (AMA), are introduced into Polysulfone backbone in terms of side chains firstly, and then heat-initiated crosslinking occurs during the membrane formation along with the evaporation of solvent and aggregation of polymer chains. For comparison, the conventional AEM is also prepared by heterogeneous amination. Series of characterizations, including chemical composition analyses and micro-structure observations, confirm that desired AEMs are fabricated successfully with a simultaneous occurrence of micro-phase segregation and self-crosslinking. Furthermore, the water uptake, membrane resistance, membrane homogeneity, membrane permselectivity, and thermal, mechanical and chemical stability are investigated to understand the effects of the formed membrane structure. Especially, as-prepared AEMs display outstanding acid block performances. For example, strong base DMAA-4 increase the current efficiency of ED-based acid enrichment to 98.63%, far ahead of that of conventional TMA-4. This work not only indicates acid block performance can be imparted to the strong base AEM but also make it possible to perform the ED-based reclamation of waste acid economically and efficiently.

The core-shell CeO2:Er,Yb@W18O49 heterojunction is successfully synthesized via the facile solvothermal method. The octahedral CeO2:Er,Yb nanocrystal's core exhibits green (2H11/2, 4S3/2 → 4I15/2), red (4F9/2 → 4I15/2) and NIR (4I11/2 → 4I15/2 and 4I13/2 → 4I15/2) emission under 980 nm laser diode excitation, and the multiband emissions are absorbed by the W18O49 nanowire's shell, re-exciting its higher energy localized surface plasmon resonances (LSPR). With the excitation of 980 nm, the photocatalytic property of CeO2:Er,Yb@W18O49 for hydrogen (H2) evolution from ammonia borane (BH3NH3), a three-fold increase compared to W18O49, is researched. The application of natural sunlight for the production of H2 is studied, and an obvious H2 production enhancement compared to the use of W18O49 (two-fold) is also observed. This remarkable enhancement in the catalytic activity of CeO2:Er,Yb@W18O49 heterostructures is ascribed to the re-excitation of LSPR by multiband emissions of CeO2:Er,Yb.

Upon dehydration, a dinuclear Fe(II)–Dy(III) cluster {FeDy(H2O)2} undergoes two-step single-crystal-to-single-crystal (SCSC) transformation, giving another dinuclear cluster {FeDy(H2O)} and finally a tetranuclear cluster {Fe2Dy2}. Further, both the single crystals of {FeDy(H2O)} and {Fe2Dy2} can return to {FeDy(H2O)2} by rehydration. This multistep SCSC transformation leads to notable OFF/Part/ON switching of single-molecule magnet behaviour.

Slow relaxation of magnetization is observed in a neodymium(III) single-ion magnet based on phosphine oxide, which successfully extends our pentagonal bipyramidal family to light lanthanides. Comprehensive magnetic characterizations reveal that the magnetic dynamics follow the power law that corresponds to a Raman process, despite an energy splitting of 207 cm–1 evidenced by the ab initio calculation. Compared with a similar complex, the magnetic dynamics and magneto-structural correlations are clarified, providing deeper insight into the pursuit of promising light lanthanide single-molecule magnets.

A chiral Co(II)-based coordination polymer, [Co3(pimda)2(H2O)5] (1, H3pimda = 2-propyl-1H-imidazole-4,5-dicarboxylic acid) with 3D hyperkagome topology is reported. Upon heating/cooling, the water molecules which are coordinated to a pair of crystallographically symmetric Co(II) ions are removed/recovered discretely in two steps, giving [Co3(pimda)2(H2O)4] (2) and [Co3(pimda)2(H2O)3] (3), which is evidenced by the reversible single-crystal-to-single-crystal (SCSC) structural transformations. As the coordination geometry of the two Co(II) ions changes from octahedron to trigonal bipyramid, obvious color change from pink for 1 to dark violet for 2 and 3 is observed. Further magnetic measurements demonstrate the presence of a solvatomagnetic effect from paramagnets for 1 and 2 to weak ferromagnet for 3. Moreover, as revealed by the variable-temperature crystallographic measurements, the first and second dehydration temperatures could be controlled from 298 K (25 °C) and 383 K (110 °C) sealed in a capillary (...

Magneto-structural correlation studies of mononuclear intermediate S = 3/2 Fe(III) complexes, (PMe3)2FeCl3 (1) and (PMe2Ph)2FeCl3 (2), demonstrate the influence of local symmetry on magnetic anisotropy. Symmetric compound 1 is characterized by a zero-field splitting (ZFS) parameter of D = −50(2) cm–1, leading to the observation of slow magnetic relaxation with an energy barrier of 81 cm–1 along with magnetic hysteresis up to 4 K, whereas symmetrically perturbed compound 2 displays a much reduced ZFS parameter of D = −17(1) cm–1 and energy barrier of Ueff = 46 cm–1.

A novel dysprosium(III)-containing polytungstoarsenate, [{(AsW9O33)3Dy2(H2O)4W4O9(H2O)}2(NH2(CH2PO3)2)]33–, comprising two identical subunits bridged by an organophosphonate ligand shows single-molecule-magnet (SMM) behavior. Magnetic studies reveal that this complex exhibits a butterfly-shaped hysteresis loop up to 8 K, and a thermally activated energy barrier of 101(5) K reached a breakthrough among all polyoxometalate-supported SMMs.

Materials with hysteretic multi-step spin-crossover (SCO) have potential application in high-order data storage. Here, an unprecedented hysteretic four-step SCO behavior with the sequence of LS↔HS0.25 LS0.75 ↔HS0.5 LS0.5 ↔ HS0.75 LS0.25 ↔HS is found in a three-dimensional (3D) Hofmann-type metal-organic framework (MOF), which is evidenced by magnetic, differential scanning calorimetry, and crystal data. Further experiments involving guest exchange leads to the first reversible modulation of four-, two-, and one-stepped SCO behaviors, which provides a new strategy for developing multi-step SCO materials.

Herein, the coordination chemistry of a series of Cu(II) complexes of various aminoalcohol and benzoate ligands was explored. The pH-dependent reactions of copper(II) salts with propanolamine (Hpa), N-methyl diethanolamine (H2mdea), triethanolamine (H3tea), and nbutyl-diethanolamine (H2budea) were carried out in the presence of various benzoates (benzoic acid, 2-hydroxy benzoic acid, 4-hydroxy benzoic acid, 3-methoxy benzoic acid, and 4-methoxy benzoic acid). The resulting complexes [Cu2(pa)2(benzoate)2] (1), [Cu2(pa)2(3-methoxybenzoate)2] (2), [Cu2(pa)2(4-methoxybenzoate)2] (3), [Cu2(H2tea)2(benzoate)2]·2H2O (4), [Cu2(H2tea)2(2-hydroxybenzoate)2]·2H2O (5), [Cu2(H3tea)2(4-hydroxybenzoate)2][Cu(Htea)2]·2H2O (6), [Cu(H2mdea)2][benzoate]2 (7), [Cu(H2mdea)2][4-methoxybenzoate]2 (8), [Cu(H2bdea)2][2-hydroxybenzoate]2 (9), [Cu2(benzoate)4(benzoic acid)2] (10), [Cu2(4-methoxybenzoate)4(CH3CN)2]·4CH3CN (11) and [Cu3(H2tea)2(benzoate)2(NO3)2] (12) were formed as mono-, di- or trinuclear entities depending upon the pH conditions of the reaction. The complexes were characterized employing spectral, magnetic, single-crystal X-ray and DFT/TDDFT studies. 7 and 8 exhibited emission peaks at 510 and 460 nm, respectively, in the solid-state photoluminescence (PL) spectra. The temperature variable magnetic properties of 1–12 revealed the presence of antiferromagnetic (in 1–3 and 7–11) or ferromagnetic interactions (in 4–6 and 12) with Curie constants C = 0.24 (7), 0.28 (8) or 0.35 cm3 K mol−1 (9) and Weiss constants θ = −0.34 (7), −0.32 (8) or −0.40 (9) K for the mononuclear complexes. The dinuclear complexes demonstrated J values of −89.2(2) (1), −71.1(3) (2), −59.6(1) (3), 98(1) (4), 79.1(2) (5), −85.4(2) (10) and −89.5(2) (11) cm−1. Strong ferromagnetic interactions were observed in the case of 6 (J = 172(3) cm−1 and zJ′ = 2.3(2) cm−1), which were comparable with those of 12 (J12 = 197(2) cm−1, J13 = −9.3(3) cm−1). A correlation exists between the Cu–O–Cu angle and magnetic coupling in di- and trinuclear Cu(II) complexes. Moreover, 4–6 were active catalysts for the oxidation of 3,5-DTBC to 3,5-DTBQ and showed catecholase activity in the order 4 > 5 > 6 (Kcat = 943 (4), 698 (5) and 553 h−1 (6)). This order can be rationalized in terms of the electron density on the ligand, which neutralizes the effective positive charge on Cu(II), thus forming the less or more stable intermediate. The order of catecholase activity and the electronic spectral properties of 4–6 were also investigated by DFT and TDDFT studies, respectively.