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Comprehensive Summary: The reaction of DyCl3⋅6H2O with a rigid diacylhydrazone ligand (H2L) afforded a trinuclear precursor [Dy3L2Cl3(H2O)2(CH3OH)]Cl2⋅3CH3OH (1). The replacement of the Cl– ions and the coordinating solvents by the aryloxides ligands (Lx)– yields three trinuclear complexes [Dy3L2(Lx)5]⋅nsol (x = 1,2‐naphthol (2); x = 2,7‐hydroxycoumarin (3); and x = 3, phenol (4)). In complexes 2—4, two end Dy3+ centers adopt almost identical N4O4 coordination sphere of D6h geometry while the central one adopts N4O5 coordination sphere in Cs geometry. Magnetic measurements reveal weak antiferromagnetic interactions in the hydrated samples 2e—4e and two‐step slow relaxation process under zero dc field with effective energy barriers Ueff of 439 and 91 K, 353 and 40 K, 466 and 89 K for SR and FR in 2e—4e, respectively. Such dynamic magnetic behaviour for 4 persists in the magnetically diluted sample of 4@Y. Complex 4 possesses the short Dy‐Oaryloxide bond distance of 2.055(18) Å, and the largest Ueff among the reported linear trinuclear dysprosium complexes. Moreover, the functionalized aryloxides ligands (Lx)– show photoluminescence via intramolecular energy transfer, making 2e—4e luminescent Dy3+ SMMs with high energy barriers. [ABSTRACT FROM AUTHOR]

Complete-active-space self-consistent field (CASSCF) calculations combined with different active spaces have been performed on four novel two-coordinate Co(II) imido complexes with the [CoN]+ core for the short Co＝N bond. The computational demand of the selected CAS (11, 8) for all complexes is acceptable, and it also gives the most accurate results compared with the experiments. CAS (11, 8) calculations show that shortening the Co＝N bond would result in the decrease of the total orbital angular momentum L, and then the weakening of the spin–orbit coupling interaction. However, the energy level splittings for different Co＝N bonds are almost close to each other due to the continuously increasing crystal field around Co(II). Thus, the decrease of the axial symmetry is the most important factor on the lower energy barriers for two-coordinate Co(II) imido complexes with shorter Co＝N bonds. Breaking the [CoN]+ core through lengthening the Co＝N bonds for two-coordinate Co-based complexes is a good choice to enhance the energy barrier. [ABSTRACT FROM AUTHOR]

Three CoII complexes, [Co2(H2L1)2](ClO4)4·4CH3OH (1), [Co2(H4L2)2](ClO4)4 (2) and [Co4(H4L2)4](ClO4)8 (3), were constructed by the self-assembly of the symmetrical dihydrazone ligands H2L1 and H4L2 with CoII ions under different synthetic conditions. The fish-bone-like complex 1 was obtained using the ligand H2L1 in methanol via the solvothermal method, while the self-assembly of H4L2 with CoII ions is solvent-dependent, producing the fish-bone-like complex 2 and [2 × 2] grid-like complex 3. Magnetic susceptibility measurements and theoretical calculations reveal that the large negative D values for the three complexes stem from their easy-axis magnetic anisotropy. Ac magnetic susceptibility measurements disclosed field-induced slow magnetic relaxation behaviors and the presence of Raman and/or direct processes of the three complexes at various applied dc fields. [ABSTRACT FROM AUTHOR]

Two lanthanide complexes with formulae [DyIII(LN5)(pentafluoro-PhO)3] (1) and [DyIII(LN5)(2,6-difluoro-PhO)2](BPh4) (2) (LN5 = 2,14-dimethyl-3,6,10,13,19-pentaazabicyclo[13.3.1]nonadecal (19),2,13,15,17-pentaene) were structurally and magnetically characterized. DyIII ions lie in the cavity of a five coordinate nitrogen macrocycle, and in combination with the introduction of multi-fluorinated monodentate phenoxyl coligands a high axiality coordination symmetry is built. Using the pentafluorophenol co-ligand, complex 1 with a D2d coordination environment, is obtained and displays moderate single-molecule magnets (SMMs) behavior. When difluorophenol co-ligands were used, a higher local axisymmetric pentagonal bipyramidal coordination geometry was observed in complex 2, which displays apparent slow magnetic relaxation behavior with a hysteresis temperature of up to 5 K. Further magnetic studies of diluted samples combined with ab initio calculations indicate that the high axiality plays a crucial role in suppressing quantum tunneling of magnetization (QTM) and consequently results in good slow magnetic relaxation behavior. Different fluoro-substituted phenoxyl co-ligands have phenoloxy oxygen atoms with different electrostatic potentials as well as a different number of phenoloxy coligands along the magnetic axis, resulting in different ligand field strengths and coordination symmetries. [ABSTRACT FROM AUTHOR]

A new hydrazone Schiff base ligand was condensed from 2-hydroxy-3-methoxybenzaldehyde and pyrimidine-4-carbohydrazide {H2L = (E)-N′-(2-hydroxy-3-methoxybenzylidene)pyrimidine-4-carbohydrazide}, which was used to assemble two new Dy2 complexes Dy2L2(DMF)2(NO3)2 (1) and Dy2L2(DMF)2(AcO)2 (2). Notably, the coordinated anions have a subtle effect on the coordination configurations of the Dy3+ ions and the magnetic properties of the two Dy2 complexes. The Dy3+ ions in 1 and 2 have the same N2O5 coordination environment but show the triangular dodecahedron and the biaugmented trigonal prism coordination configurations, respectively. Magnetic measurements revealed that both 1 and 2 have intramolecular ferromagnetic interactions between the Dy3+ ions and show single-molecule magnet behaviors at 0 Oe, with Ueff/k values of 58.2 K for 1 and 59.9 K for 2. These magnetic properties may be explained by theoretical calculations. [ABSTRACT FROM AUTHOR]

Single‐molecule toroics are molecular magnets with vortex distribution of magnetic moments. The coupling between magnetic and electric properties such as the magnetodielectric effect will provide potential applications for them. Herein, the observation of significant magnetodielectric effect in a triangular Dy3 crystal with toroidal magnetic moment and multiple magnetic relaxations is reported. The analysis of magnetic and electric properties implies that the magnetodielectric effect is closely related to the strong spin‐lattice coupling, magnetic interactions of Dy3+ ions, as well as molecular packing models. [ABSTRACT FROM AUTHOR]

Synthesis of 3d–4f single molecule magnets (SMMs) with novel topologies and exploration of the magnetic relaxation mechanism of SMMs have continuously received considerable attention because high performance SMMs could be obtained. In this work, we selected N-3-methoxysalicylidene-2-amino-3-hydroxypyridine (H2L) and di-2-pyridyl ketone (dpk) for reaction with Ni(NO3)2·6H2O, Dy(NO3)3·5H2O and trimethylamine in a CH3OH solution, and a novel Ni4Dy4 complex, [Ni4Dy4(L)6(L′)2{(py)2C(OCH3)O}2(μ3-CO3)2(CH3OH)2]·10CH3OH·13H2O (1, (py)2C(OCH3)(OH) = the hemiacetal form of dpk), was obtained. The magnetic diluted complex, [Ni4Y3.91Dy0.09(L)6(L′)2{(py)2C(OCH3)O}2(μ3-CO3)2(CH3OH)2]·10CH3OH·12H2O (2), and the Y analogue of 1, [Ni4Y4(L)6(L′)2{(py)2C(OCH3)O}2(μ3-CO3)2(CH3OH)2]·10CH3OH·11H2O (3), were also obtained. The carbonate ions in 1–3 were formed by spontaneous fixation of atmospheric CO2. Structural analysis revealed that the metallic core in 1 can be viewed as a Ni2Dy2 butterfly connecting two NiDy subunits on each side. To our knowledge, the structural topologies of 1–3 were not reported previously. The magnetic susceptibilities of 3 were fitted by PHI, indicating that the magnetic coupling between Ni1 and Ni1a in the "Ni2Y2 butterfly" subunit of 3 is ferromagnetic. Alternating-current (ac) susceptibility studies revealed that 1–2 exhibit single molecule magnet behavior under a zero dc field. [ABSTRACT FROM AUTHOR]

Photocontrolled magnetic properties are fundamental for the applications of molecular magnets, which have the features of high time and space resolution; however, such magnetic properties are highly challenging to be achieved owing to the weak light–matter interactions. Herein, the influence of in situ light irradiation on the field-induced magnetization dynamics of two Er(III) coordination polymers 1 and 2 with the same coordination skeletons but different halogen substituents was studied. 1 and 2, and their in situ photoexcited products 1a and 2a, display field-induced magnetization dynamics based on Orbach and/or Raman processes. The magnetization dynamics are fine-modulated by the synergetic effect of light irradiation and a ligand substituent, due to the charge re-distribution of the excited states of the ligand. [ABSTRACT FROM AUTHOR]

The modular construction method provides a feasible way to construct pre-designed cyano-bridged {LnIIIMIV/V} systems with more attractive structures and adjustable interactions between 4d/5d and 4f ions. In this work, the pentadentate Schiff-base ligands H2Ln (H2L1: 2,6-diacetylpyridine bis(nicotinoylhydrazone); H2L2: 2,6-diacetylpyridine bis(isonicotinoylhydrazone)) with multiple coordination sites were designed to coordinate with DyIII ions firstly, and then combined with K4M(CN)8·2H2O (M = W, Mo) by a liquid–liquid diffusion method to successfully synthesize two trinuclear structures {Dy[MIV(CN)8]0.5(HL1)(H2O)3}2·8H2O (1: M = W; 2: M = Mo), and two dinuclear structures {[Dy[MIV(CN)8](H3L2)(H2O)3]}·sol (3: M = W, sol = 11.5H2O; 4: M = Mo, sol = 2CH3OH·9.5H2O). Interestingly, deprotonation occurs in ligand H2L1 during the formation of complexes 1 and 2, while deprotonation/protonation processes both occur in ligand H2L2 during the synthesis of complexes 3 and 4. Magnetic analyses reveal that complexes 1–4 are all field-induced single-ion magnets (SIMs). The energy barriers (Ueff/kB) of complexes 1 and 2 are 92.83 K and 101.08 K, respectively, which are nearly three-fold higher than those of complexes 3 (30.19 K) and 4 (32.77 K). Ab initio calculations were performed on these series of {LnIIIMIV} heteronuclear complexes to provide more insights into the magnetic relaxation properties. This work provides another example of improving the SMM behaviors of cyano-bridged {LnIIIMIV} systems by deprotonation/protonation at different sites in the ligands. [ABSTRACT FROM AUTHOR]

The electronic state in terms of charge and spin of metal sites is fundamental to govern the catalytic activity of a photocatalyst. Herein, we show that modulation of the electronic states of Cu sites, without changing the coordination environments, of two metal‐organic supramolecular assemblies based on π⋅⋅⋅π stacking can significantly improve photocatalytic activity. The use of these heterogeneous photocatalysts, without using noble metal cocatalysts, resulted in an increase of the hydrogen production rate from 522 to 3620 μmol h−1 g−1. A systematical analysis revealed that the charge density and spin density of the metal centers are efficiently modulated via the modulation of the coordination fields around active copper (II) centers by the variation of the non‐coordination groups of terminal ligands, leading to the significant enhancement of photocatalytic activity. This work provides an insight into the electronic state of active metal centers for designing high‐performance photocatalysts. [ABSTRACT FROM AUTHOR]

The electronic state in terms of charge and spin of metal sites is fundamental to govern the catalytic activity of a photocatalyst. Herein, we show that modulation of the electronic states of Cu sites, without changing the coordination environments, of two metal‐organic supramolecular assemblies based on π⋅⋅⋅π stacking can significantly improve photocatalytic activity. The use of these heterogeneous photocatalysts, without using noble metal cocatalysts, resulted in an increase of the hydrogen production rate from 522 to 3620 μmol h−1 g−1. A systematical analysis revealed that the charge density and spin density of the metal centers are efficiently modulated via the modulation of the coordination fields around active copper (II) centers by the variation of the non‐coordination groups of terminal ligands, leading to the significant enhancement of photocatalytic activity. This work provides an insight into the electronic state of active metal centers for designing high‐performance photocatalysts. [ABSTRACT FROM AUTHOR]

The synthesis, single-crystal structures and magnetic properties of two new double-zigzag-chain cyano-bridged heterobimetallic {[MII(Py-NOH)2][FeIII(Tp*)(CN)3]2}·H2O ([Fe III2 MII]) (Py–NOH = 4-pyridinealdoxime, Tp* = tris(3,5-dimethylpyrazol-1-yl)borohydride, M = Ni (1), Fe (2)) compounds are reported. The crystal structures of both compounds were determined by single-crystal X-ray diffraction. Complexes 1 and 2 are isostructural, with the crystal structure comprising neutral double-zigzag (4,2-ribbon-like) bimetallic chains. The FeIII ion is coordinated by three cyanide carbon atoms and three nitrogen atoms of Tp* anions. However, the MII ion is surrounded by four cyanide nitrogen atoms and two nitrogen atoms from two Py-NOH ligands. The crystal structures and magnetic studies demonstrate that both complexes behave as single-chain magnetics (SCMs) with intrachain ferromagnetic coupling. Furthermore, [Fe III2 NiII] exhibits an excellent coercive field of 0.42 T at 1.8 K, among cyano-bridged 3d transition-metal-based SCMs reported thus far. Preliminary theoretical calculations provide a deep understanding of the magnetic properties of [Fe III2 NiII]. [ABSTRACT FROM AUTHOR]

Four benzeneboron‐capped mononuclear CoII complexes with different alkyl substitutions on the fourth position of phenylboronic acid were obtained. The CoII ions are all wrapped by the pocket‐like ligands and located in trigonal prismatic coordination geometries. Alternating‐current magnetic susceptibility measurements reveal that they show different magnetization dynamics, such as distinct relaxation rates at the same temperature, the faster QTM rates for the ethyl and propyl substituted complexes, as well as different relaxation processes. Magneto‐structural correlation study reveals that the various deviations of coordination geometry of CoII ion, diverse crystal packings and possible different vibration modes of substituents caused by modifying alkyl chains are the key factors affecting the magnetization dynamics. This work demonstrates that the alkyl chains even locating far away from the metal center can have a large impact on the magnetic behavior of the CoII complex with a very rigid coordination geometry, offering a new perspective towards transition metal based single‐molecule magnets. [ABSTRACT FROM AUTHOR]

The utilization of the di-pyrrolyl Schiff base ligand H2L (H2L = N-((1H-pyrrol-2-yl)methyl)-1-(1H-pyrrol-2-yl)methanimine) in organolanthanide chemistry is presented. The 1 : 2 reaction of [Ln(N(SiMe3)2)3] (Ln = Dy, Ho, Er, and Gd) with H2L in THF followed by recrystallization in THF/Tol or Tol generated complexes [Dy2(HL)2(L)2(THF)2]·2THF (1·2THF), [Ho2(HL)2(L)2(THF)2] (2), [Er2(HL)2(L)2(THF)2]·4Tol (3·4Tol), and [Gd2(HL)2(L)2(THF)2] (4). In the doubly deprotonated ligand [L]2−, one pyrrolyl ring adopts the η5 coordination mode, and the other pyrrolyl moiety behaves as an η1 ligand. The deprotonated pyrrolyl scaffold of the [HL]− ligand exhibits the η1 coordination mode. Thus, the two metal centers both display a half-sandwich configuration. Studies of the dc magnetic susceptibility of 1-4 at variable temperatures showed that weak antiferromagnetic interactions exist in these compounds. The ac magnetic susceptibility measurements for 1 and 2 indicated that they did not display single-molecule magnetic (SMM) properties. The magnetic properties of 1 and 2 were further explained by DFT calculations. [ABSTRACT FROM AUTHOR]

Synthesis of air-stable and high-performance single-molecule magnets (SMMs) is challenging. Here, a heptadentate pentapyridyldiamine (BPA-TPA) ligand and fine-tuned axial phenoxy ligands are used to synthesize two triangular dodecahedral Dy(III) complexes [Dy(BPA-TPA)(4-methoxy-PhO)](BPh4)2·3CH2Cl2 (4) and [Dy(BPA-TPA)(2,4-dimethyl-PhO)](BPh4)2·0.85CH2Cl2 (5). Both complexes have high effective barriers exceeding 400 K and magnetic hysteresis up to 8 K, which is ascribed to one strong and short Dy–O bond combined with seven weak Dy–N bonds. Ab initio calculations reveal the thermally activated quantum tunneling of magnetization through the first excited Kramers doublet, due to the presence of a strong axial Dy–O crystal ligand. Substitution of the phenoxy ligand leads to more constrained vibrations, improving the magnetic hysteresis behavior for 5. [ABSTRACT FROM AUTHOR]

Cyano‐bridged 4d–4f molecular nanomagnets have re‐called increasing research interests in molecular magnetism since they offer more possibilities in achieving novel nanomagnets with versatile structures and magnetic interactions. In this work, four β‐diketone ligands bearing different substitution N‐sites were designed and synthesized, namely 1‐(2‐pyridyl)‐3‐(3‐pyridyl)‐1,3‐propanedione (HL1), 1,3‐Bis (3‐pyridyl)‐1,3‐propanedione (HL2), 1‐(4‐pyridyl)‐3‐(3‐pyridyl)‐1,3‐propanedione (HL3), and 1,3‐Bis (4‐pyridyl)‐1,3‐propanedione (HL4), to tune the magnetic relaxation behaviors of cyano‐bridged {DyIIIMoV} systems. By reacting with DyCl3 ⋅ 6H2O and K4Mo(CN)8 ⋅ 2H2O, four cyano‐bridged complexes, namely {[Dy[MoV(CN)8](HL1)2(H2O)3]} ⋅ 6H2O (1), {[Dy[MoV(CN)8](HL2)(H2O)3(CH3OH)]}2 ⋅ 2CH3OH ⋅ 3H2O (2), {[Dy[MoV(CN)8](HL3)(H2O)2(CH3OH)] ⋅ H2O}n (3), and {[Dy[MoV(CN)8](HL4)2(H2O)3]} ⋅ 2H2O⋅CH3OH (4) were obtained. Structural analyses revealed that 1 and 4 are binuclear complexes, 2 has a tetragonal structure, and 3 exhibits a stair‐like polymer chain structure. The DyIII ions in all complexes have eight‐coordinated configurations with the coordination spheres DyO7N1 for 1 and 4, DyO6N2 for 2, and DyO5N3 for 3. Magnetic measurements indicate that 1 is a zero‐field single‐molecule magnet (SMM) and complexes 2–4 are field‐induced SMMs, with complex 4 featuring a two‐step relaxation process. The magnetic characterizations and ab initio calculations revealed that changing the N‐sites in the β‐diketone ligands can effectively alter the structures and magnetic properties of cyano‐bridged 4d–4f nanomagnets by adjusting the coordination environments of the DyIII centers. [ABSTRACT FROM AUTHOR]

Using a novel tricompartmental hydrazone ligand, a set of trinuclear Dy3 complexes has been isolated and structurally characterized. Complexes Dy3 ⋅ Cl, Dy3 ⋅ Br, and Dy3 ⋅ ClO4 feature a similar overall topology but different anions (Cl−, Br−, or ClO4−) in combination with exogenous OH− and solvent co‐ligands, which is found to translate into very different magnetic properties. Complex Dy3 ⋅ Cl shows a double relaxation process with fast quantum tunneling of the magnetization, probably related to the structural disorder of μ2‐OH− and μ2‐Cl− co‐ligands. Relaxation of the magnetization is slowed down for Dy3 ⋅ Br and Dy3 ⋅ ClO4, which do not show any structural disorder. In particular, fast quantum tunneling is suppressed in case of Dy3 ⋅ ClO4, resulting in an energy barrier of 341 K and magnetic hysteresis up to 3.5 K; this makes Dy3 ⋅ ClO4 one of the most robust air‐stable trinuclear SMMs. Magneto‐structural relationships of the three complexes are analyzed and rationalized with the help of CASSCF/RASSI‐SO calculations. [ABSTRACT FROM AUTHOR]

Photosensitive lanthanide‐based single‐molecule magnets (Ln−SMM) are very attractive for their potential applications in information storage, switching, and sensors. However, the light‐driven structural transformation in Ln−SMMs hardly changes the coordination number of the lanthanide ion. Herein, for the first time it is reported that X‐ray (λ=0.71073 Å) irradiation can break the coordination bond of Dy−OH2 in the three‐dimensional (3D) metal‐organic framework Dy2(amp2H2)3(H2O)6 ⋅ 4H2O (MDAF‐5), in which the {Dy2(OPO)2} dimers are cross‐linked by dianthracene‐phosphonate ligands. The structural transformation proceeds in a single‐crystal‐to‐single‐crystal (SC‐SC) fashion, forming the new phase Dy2(amp2H2)3(H2O)4 ⋅ 4H2O (MDAF‐5‐X). The phase transition is accompanied by a significant change in magnetic properties due to the alteration in coordination geometry of the DyIII ion from a distorted pentagonal bipyramid in MDAF‐5 to a distorted octahedron in MDAF‐5‐X. [ABSTRACT FROM AUTHOR]

Two novel Co–Dy heterometallic complexes, namely, [Co III2 Dy III2 (HL)L{(py)2CO2}{(py)2C(OCH3)O}(NO3)4CH3OH]·2CH3CN·2.5H2O (1, H3L = 2-((2-hydroxy-benzylidene)amino)propane-1,3-diol, (py)2C(OH)2 = the gem-diol form of di-2-pyridyl ketone (dpk) and (py)2C(OCH3)OH = the hemiacetal form of dpk) and [CoIII{(py)2C(OH)O}2][Co II2 Dy III4 DyIII(HL)4(L)4]·3CH3CN·15H2O (2), have been obtained by employing H3L, dpk and Dy(NO3)3·5H2O reacting with Co(NO3)2·6H2O or anhydrous Co(CH3CO2)2 in the solutions of CH3OH and CH3CN (V/V = 1/20) containing N(Me)4OH·5H2O or triethylamine. Structural analysis indicated that two DyIII and two CoIII in 1 formed a star-like topology, while the metal ions in [Co II2 Dy III4 DyIII(HL)4(L)4]− of 2 formed a cross-shaped topology, in which one DyIII and two CoII formed a linear Co II2 DyIII paramagnetic unit. Interestingly, the paramagnetic Co II2 DyIII units in 2 were isolated not only by four diamagnetic CoIII in the [Co II2 Dy III4 DyIII(HL)4(L)4]−, but also by the diamagnetic [CoIII{(py)2C(OH)O}2]+. More interestingly, the distortion of the square antiprism (SAP-8) coordination geometry of DyIII in 2 can be ascribed to the presence of four long Dy–O bonds and four short Dy–O bonds, which could result from the discrepancies of the polarization of CoII and CoIII. Magnetic studies indicated that 1 exhibit two types of magnetic relaxation behavior, in which the magnetic relaxation of the fast relaxation (FR) phase is mainly governed by QTM, while that of the slow relaxation (SR) phase is mainly governed by Orbach and Raman processes with an effective energy barrier (Ueff) value of 59.4(9) K. To our knowledge, the Ueff value is relatively high among the reported CoIII–DyIII heterometallic complexes. For 2, it only shows slow relaxation behavior with a Ueff of 6.43 K. Ab initio calculations revealed that the SR phase and FR phase are governed by the magnetic relaxation of Dy2 and Dy1, respectively, though the axial symmetry of Dy2 (muffin, Cs) is lower than that of Dy1 (triangular dodecahedron, D2d). However, for 2, the theoretical calculations indicated that the severely compressed SAP-8 geometry of DyIII leads to a relatively low Ueff value. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Better understanding the determining factors of dynamic magnetic relaxation in polynuclear lanthanide based single‐molecule magnets (SMMs) remains a challenge due to the complexity of such architectures involving interactions between the magnetic centers. To address this issue, two structurally related heterometal DyIII2ZnII2 SMMs, [Zn2Dy2(L)4(Ac)2(DMF)(CH3OH)]·CH3OH·2H2O (1) and [Zn2Dy2(L)4(Ac)2(DMF)2]·4CH3CN (2) (H2L = (E)‐2‐((2‐hydroxy‐3‐methoxybenzylidene)amino)‐4‐methyphenol, DMF = N,N‐dimethylformamide), are introduced and investigated. Through modifying the auxiliary ligands on one DyIII site while retaining that on the other DyIII, the intramolecular magnetic interactions and relaxation dynamics in these two heterometallic‐DyIII2ZnII2 SMMs can be tuned, demonstrating a dramatic change in the magnet relaxation behavior with energy barrier changing from a negligible value for 1 to 305 K for 2. Ab initio calculations reveal that changing the coordination geometries on the DyIII sites can significantly affect the magnetic interactions as well as single‐ion anisotropy. [ABSTRACT FROM AUTHOR]

Materials that coexist magnetic and electric properties on the molecular scale in single‐molecule magnets (SMMs) with peculiar quantum behaviors have promise in molecular electronics and spintronics. Nevertheless, such molecular materials are limited in potentials because their magnetic signal cannot be transformed into an electrical signal through magnetoresistance or Hall effects for their high insulativity. The discovery of an entirely new material, ferroelectric SMMs (FE SMMs) is reported. This FE SMM also shows single‐molecule magnetic behaviors, toroidal magnetic moments, and room‐temperature ferroelectricity. The toroidal moment is formed by a vortex distribution of magnetic dipoles in triangular Dy3 clusters. The analysis of ac magnetic susceptibility reveals the coexistence of three distinct magnetic relaxation processes at low temperatures. The ferroelectricity is introduced by incorporating polar alcohol molecules in the structure, which is confirmed by the X‐ray diffraction and optical second harmonic generation (SHG) measurements. Moreover, the dielectric measurements reveal a ferroelectric‐to‐ferroelectric phase transition around 150 K due to the symmetry change from Pc to Pna21. The coexistence of toroidal moment and ferroelectricity along with quantum magnetism in the rare‐earth single‐molecule magnets yields a unique class of multiferroics. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Precise modulation of the magnetic anisotropy of metal ions remains highly important for the development of high–performance single‐molecule magnets (SMMs). We herein reported the synthetic, structural, spectral, magnetic, and computational studies on four mononuclear CoII complexes in a distorted octahedral environment. The change of the organosulfonate anions triggers significant modification of the distorted octahedral CoN6 coordination sphere, which enables us to tackle the influence of the structural distortion on the magnetic anisotropy in these complexes. Magnetic measurements revealed that the four complexes possess easy–plane magnetic anisotropy with large and positive zero‐field splitting parameters, which decrease with the increasing distortion of the pseudo–octahedral CoII coordination geometry. This correlation was further confirmed by high–frequency/–field EPR (HF–EPR) spectra and theoretical calculations. Dynamic magnetic susceptibility measurements indicate that these complexes both exhibit slow magnetic relaxation under an external dc field, indicating the field‐induced single‐ion magnets (SIMs) of the four complexes. These results indicate that structural distortion plays an important role in the magnetic anisotropy of CoII complexes and should be carefully considered in the design of molecular complexes with high magnetic anisotropy. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Two new bis-bidentate imidazole-substituted nitronyl nitroxide biradicals, BNITIm-C2 (BNITIm-C2 = 1,1′-(1,2-ethanediyl)bis(1H-imidazole-2–4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxy-3-oxide)) and BNITIm-C4 (BNITIm-C4 = 1,1′-(1,4-butanediyl)bis(1H-imidazole-2–4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxy-3-oxide)), and two series of lanthanide complexes, namely [(BNITIm-C2)Ln(NO3)3](MeOH) (Ln = Gd (1Gd) and Tb (2Tb)), (BNITIm-C2)Dy(NO3)3 (3Dy) and (BNITIm-C4)[Ln(hfac)3]2(C7H8)2 (Ln = Gd (4Gd), Tb (5Tb) and Dy (6Dy), hfac = hexafluoroacetylacetonate), have been prepared and characterized structurally and magnetically. Single crystal X-ray crystallographic analyses revealed that complexes 1Gd–3Dy exhibit 1D chain structures where the Ln(NO3)3 units are bridged by the BNITIm-C2 bis-bidentate biradical, while complexes 4Gd–6Dy exhibit binuclear structures with two Ln(hfac)3 units bridged by the BNITIm-C4 biradical. The bulky hfac anions prohibit the further coordination of LnIII to another NIT ligand and the formation of a similar 1D chain structure. Due to the very long intra- and intermolecular distances of the spin centers, complexes 1Gd–3Dy can be magnetically regarded as an isolated 2p–4f–2p tri-spin system while complex 4Gd–6Dy can be regarded as an isolated 2p–4f bi-spin system. Magnetic analyses on the two GdIII compounds revealed the ferromagnetic GdIII–NIT interactions and antiferromagnetic NIT–NIT interactions through the GdIII ion in 1Gd. Alternating-current (ac) magnetic susceptibility investigations revealed that complex 5Tb exhibits the typical SMM behavior under a zero dc field while complex 6Dy was proved to be a field-induced SMM. Ab initio calculations were performed on complexes 2Tb and 5Tb to understand their magnetic anisotropy together with their different magnetic dynamics. [ABSTRACT FROM AUTHOR]

Terminal fluoride ligands generate strong magnetic anisotropy in air-stable chiral dysprosium enantiomers supported by a bulky equatorial macrocycle, exhibiting a typical zero-field single-molecule magnet behaviour. [ABSTRACT FROM AUTHOR]

A dinuclear complex with the formula Dy2L2(H2L)Cl2(EtOH)2 (Dy2) has been synthesized by reacting DyCl3·H2O with a ligand H2L (H2L = N,N′-ethylenebis(salicylideneimine)) using ethanol as the solvent. Its crystal structure can be viewed as a dimer of two Dy(III) fragments, where each Dy(III) site shows a N2O6Cl coordination sphere with a pentagonal bipyramid geometry (D5h). Magnetic measurements reveal that Dy2 behaves as a single-ion magnet (SIM) under a zero field. When the field is applied, the ac magnetic susceptibilities show double and triple peaks under high (≥600 Oe) and low (<600 Oe) dc fields, respectively. In contrast to the common double relaxation pathways in SIMs, such multiple and intricate relaxation pathways have not been reported yet in the previous literature. In this work, by experimental analysis of the ac signals, we attribute the three slow relaxation pathways to quantum tunnelling of magnetization (QTM), intermolecular dipole–dipole interaction and spin reversal, respectively. In addition, ab initio calculations are used to elucidate the magnetic behaviours of Dy2. Overall, our work indicates that the interpretation of the relaxation process using double relaxation pathways is incomplete and difficult in previously reported literature. [ABSTRACT FROM AUTHOR]

Two lanthanide single-molecule magnets (SMMs) [Dy3(μ3-OH)(HL-1)3(H2O)3](NO3)2·3H3O (1, H3L-1 = (E)-3-(((8-hydroxyquinolin-2-yl)methylene)amino)propane-1,2-diol) and [Dy6(μ3-OH)4(H2L-2)4(HL-2)2(L-2)2] (2, H3L-2 = (E)-2-hydroxy-N′-(2-hydroxy-3-methoxybenzylidene)benzohydrazide) were synthesized and characterized structurally and magnetically. Complex 1 contains a triangular Dy3 core in which the three Dy3+ ions share a μ3-OH− anion and the deprotonated ligands of (HL-1)2− serve both capping and bridging functions, while 2 displays a centrosymmetric hexanuclear DyIII structure with two similar Dy3 triangular cores ligated by two fully deprotonated (L-2)3− ligands, each of which shares two μ3-OH− anions. All the DyIII ions are eight-coordinated with quasi D2d or C2v symmetry. Magnetic studies reveal that 1 exhibited two-step magnetic relaxation under an applied dc field of 800 Oe, with effective energy barriers of 40.1 and 31.0 K for the slow relaxation (SR) and fast relaxation regimes (FR), respectively. Meanwhile, 2 only showed a tail of slow magnetic relaxation at above 2 K. Ab initio calculations have been carried out to show the nature of their different magnetic properties. [ABSTRACT FROM AUTHOR]

Based on a β-diketiminate ligand, an iron(III) tetrahedral high-spin complex, [LFeIII(Cl)2] (1), and an iron(II) high-spin triangular planar complex, [LFeIICl] (2), have been synthesized and structurally characterized. Also, complex 1 can be considered as a precursor to produce 2via a reduction process, with a concomitant change in its magnetic anisotropy. Combined experiments and ab initio calculations support the observation of field-induced single-ion magnet (SIM) behaviour for 2 with an effective spin-reversal energy barrier of Ueff = 40.02 K, as a direct consequence of the large intrinsic magnetic anisotropy (easy axis) arising from out-of-state spin-orbit coupling in the trigonal planar FeII complex. Noteworthy butterfly hysteresis loops were observed from 2 up to 8 K, which represents the first case in Fe(II) complexes. [ABSTRACT FROM AUTHOR]

Two β-Diketiminate cobalt(II) compounds of formula [LCo(μ-Cl)]2·2C6H14 (1) and [LCoClPy]·0.5C7H8·0.5C6H14 (2) (L = [PhC-(PhCN-Dip)2]−, Dip = 2,6-iPr2C6H3) have been synthesized and structurally characterized by single crystal X-ray diffraction. Compound 1 exhibits a dinuclear structure, whereas 2 is a mononuclear structure having a pyridine ligand. The tetra-coordinate CoII centers in both compounds show distorted tetrahedral geometry configuration. Magnetic measurements reveal that only 2 exhibits field-induced slow relaxation of magnetization with an effective spin-reversal energy barrier of 16.27 K, though large easy-axis magnetic anisotropies for both compounds are unveiled by the analysis of ab initio calculations. Dimeric Co–Co units in 1 indicate intramolecular antiferromagnetic interaction. Compared to individual CoII fragment of 1, the first excited quartet state of 2 is strongly destabilized, leading to a smaller unquenched orbital angular momentum and D value. The comprehensive factors above are responsible for the difference in the magnetic behavior between 1 and 2. [ABSTRACT FROM AUTHOR]

Recently, the choice of ligand and geometric control of mononuclear complexes, which can affect the relaxation pathways and blocking temperature, have received wide attention in the field of single-ion magnets (SIMs). To find out the influence of the coordination environment on SIMs, two four-coordinate mononuclear Co(II) complexes [NEt4][Co(PPh3)X3] (X = Cl−, 1; Br−, 2) have been synthesized and studied by X-ray single crystallography, magnetic measurements, high-frequency and -field EPR (HF-EPR) spectroscopy and theoretical calculations. Both complexes are in a cubic space group Pa3¯ (No. 205), containing a slightly distorted tetrahedral moiety with crystallographically imposed C3v symmetry through the [Co(PPh3)X3]− anion. The direct-current (dc) magnetic data and HF-EPR spectroscopy indicated the anisotropic S = 3/2 spin ground states of the Co(II) ions with the easy-plane anisotropy for 1 and 2. Ab initio calculations were performed to confirm the positive magnetic anisotropies of 1 and 2. Frequency- and temperature-dependent alternating-current (ac) magnetic susceptibility measurements revealed slow magnetic relaxation for 1 and 2 at an applied dc field. Finally, the magnetic properties of 1 and 2 were compared to those of other Co(II) complexes with a [CoAB3] moiety. [ABSTRACT FROM AUTHOR]

While the interest in single-molecule magnets (SMMs) lies in their potential applications in information storage and quantum computing, the switching of their slow magnetic relaxation associated with dynamic crystal-to-crystal transformation is insufficiently exploited. Herein, three pentagonal-bipyramidal (PBP) Dy(III) complexes, [Dy(Bcpen)(Cl)3] (1), [Dy(Bcpen)(OPhCl2NO2)3] (2) and [Dy(Bcpen)(OPhCl2NO2)3]·0.5CH3CN (2·CH3CN), are successfully assembled, and structurally and magnetically studied (Bcpen = N,N-bis(4-chloro-2-methylenepyridinyl) ethylenediamine and Cl2NO2PhOH = 2,6-dichloro-4-nitrophenol). The molecular characteristics and magnetic properties of complexes 2 and 2·CH3CN, constructed with the motivation of modulating a magnetic switch by external stimuli, are systematically explored. Dramatically, 2 and 2·CH3CN can mutually transform through reversible single-crystal-to-single-crystal (SCSC) conversion associated with the capture and release of guest CH3CN molecules, resulting in an infrequent on/off switching of PBP Dy(III) molecule-based magnets. Further measurements on the desolvated and resolvated samples, complexes 2-re and 2·CH3CN-re, confirm the fascinating transformation processes. The magneto-structural relationship has been rationally investigated and discussed with ab initio calculations as well. [ABSTRACT FROM AUTHOR]

A series of Zn–Ln heteronuclear SMMs constructed by using a hexadentate compartment Schiff base Zn-precursor and lanthanoid ions were structurally and magnetically characterized, in which the two [Zn–Ln] moieties are bridged by a series of hydroxamic acids, resulting in double-decker tetranuclear complexes with the molecular formulae [ZnL1Ln(C2H5O)(qua)]2(CF3SO3)2·2C2H5OH ((1) Ln = Dy; (7) Ln = Yb), [ZnL1Ln(CH3O)(bnz)]2(CF3SO3)2·2CH3OH ((2) Ln = Dy), [ZnL1Ln(CH3O)(aca)]2(CF3SO3)2·2CH3OH ((3) Ln = Dy; (8) Ln = Yb), [ZnL2Dy(CH3O)(bnz)]2(CF3SO3)2·2CH3OH (4), [ZnL2Dy(CH3O)(aca)]2(CF3SO3)2·2CH3OH (5), and [ZnL3Dy(CH3O)(bnz)]2(CF3SO3)2·2CH3OH (6) (HL1 = N,N'-bis(2-hydroxy-3-methoxybenzylidene)-1,2-phenylenediamine, HL2 = N,N'-bis(2-hydroxy-3-methoxybenzylidene)-propane-1,2-diamine, HL3 = N,N'-bis(3-methoxysalicylidene)-1,3-propanediamine, qua = 2-quinolinecarboxylic acid, bnz = benzhydroxamic acid and aca = acetohydroxamic acid). Strikingly, the slow magnetic relaxation can be tuned by modifying the steric hindrance and/or electronic effect on the backbone of the Shiff base and the terminal substituents of hydroxamic acid, as well the magneto-structural correlations are studied. Furthermore, Yb congeners 7 and 8 were synthesized to explore dual-functional materials with both magnetic and fluorescence properties, and they displayed both slow magnetic relaxation and near-infrared (NIR) properties; the low temperature NIR spectroscopic data were correlated with the corresponding slow magnetic relaxation mechanism involving thermally activated ground states to the excited state. [ABSTRACT FROM AUTHOR]

A series of linear sandwich single-ion magnets containing [Er(COT)]+ fragment were selected to probe the magneto-structural correlations using ab initio methods. For prolate shaped ErIII ion, an equatorially coordinating geometry is preferable to achieve high axial anisotropy. Our calculations confirm that the increasing transversal crystal field (CF) induced by equatorial ligands truly enhances the energy barrier. However, if we continue to strengthen the transversal CF in the equatorial plane, the energy barrier inversely decreases. Our further results show that a medium ligand ring of benzene is preferable for prolate shaped ErIII ion, which can induce the modest energy splitting and the small temperature-assisted quantum tunneling of magnetization. Although the obtained energy barrier of 343.1 cm−1 for our created model [(C6H6)Er(COT)]+ is the largest, it is also much smaller than the DyIII-based compounds. [ABSTRACT FROM AUTHOR]

• Two mononuclear Dy complexes based on the luminescent chromophore coumarin ligand have been synthesized and structurally characterized. • Both Dy(III) complexes exhibited a magnetic relaxation phenomenon attributable to their large magnetic anisotropy. • Both two Dy(III) complexes displayed the distinctive emission spectra. Lanthanide luminescent single-molecule magnets (SMMs) serve as a kind of multifunctional molecular materials that have attracted extensive attention. Herein, a novel chromophore coumarin ligand 7-(diethylamino)-(2‑hydroxy-3-methoxybenzylidene)-2-oxo-2-chromene-3-carbohydrazide (Hvalcoumarin) is designed to construct the luminescent Dy(III) complexes. Two Dy complexes 1 ([D y (valcoumarin)(DMF) 2 C l 2 ]·(CHCl 3)) and 2 [Dy(valcoumarin)(DMF) 2 (NO 3) 2 ] were synthesized based on the luminescent chromophore coumarin ligand (Hvalcoumarin). X-ray crystallography reveals that the Dy(III) center in complex 1 adopts a hepta-coordinated arrangement by a distorted pentagonal bipyramidal geometry. In contrast, complex 2 exhibits a nine-coordinate arrangement by a spherical capped square antiprism geometry. Magnetic investigations reveal that 1 and 2 exhibit a slow magnetic relaxation phenomenon. Furthermore, the luminescent spectra of 1 and 2 display the characteristic emission profiles associated with Dy(III) spectra. Moreover, theoretical calculations also demonstrated the relaxation dynamics of 1 and 2. The results furnish a potent avenue for the acquisition of multifunctional molecular materials with magnetic and luminescent properties. [Display omitted] Two Dy(III) complexes based on a novel coumarin ligand have been reported, and both of them exhibited slow magnetic relaxation behavior and luminescent properties. [ABSTRACT FROM AUTHOR]

Four mononuclear 9-coordinate Dy-based complexes, [Dy(HL1)2(NO3)3(CH3OH)] (1Dy), [Dy(HL2)2(NO3)3(H2O)] (2Dy), [Dy(HL3)3(NO3)3]·CH3CN (3Dy), and [Dy(HL4)3(NO3)3] (4Dy), have been constructed by neutral Schiff-base ligands (1-[N-(4-R)aminomethylidene-2(1H)-naphthalenone, R = –Cl (HL1), –NO2 (HL2), –OCH3 (HL3), –I (HL4)). By tuning the terminal substituent group of HL ligands, the number of HL ligands coordinated to the central Dy3+ ion unexpectedly varies from 2 to 3, and the local symmetry around the Dy3+ ion reduces from D3h to Cs. Magnetic measurements reveal that 2Dy can display single-ion magnet (SIM) behavior in zero dc field, while 1Dy, 3Dy and 4Dy show field-induced slow magnetic relaxation. Ab initio calculations were employed to elucidate magnetic anisotropy in the complexes, including g-tensors, averaged transition magnetic moments and magnetic easy axes. The difference in magnetic behaviors of the four complexes can be ascribed to the terminal substituent effect of neutral Schiff-base ligands. [ABSTRACT FROM AUTHOR]

Multifunctional molecular materials combining magnetic, luminescent and dielectric properties are attractive for potential applications in spintronics and molecular devices. Herein we report three isostructural mononuclear lanthanide phosphonates, namely, Ln(NO3)3(2‐deap)3 [Ln=Dy (1Dy), Er (2Er), Yb (3Yb), 2‐deap=diethyl anthrancen‐2‐ylphosphonate] which crystallize in polar space group Pna21. Magnetic studies revealed field‐induced slow magnetization relaxation for 1Dy and 3Yb, but not for 2Er down to 1.8 K. Theoretical calculations were conducted to rationalize the magneto‐structural relationship. The photoluminescent properties are also dependent on the lanthanide ion. For 1Dy, luminescence was observed only in the visible region mainly originating from the ligand. For 2Er, luminescence was observed only in the near‐infrared (NIR) region due to a complete energy transfer from the ligand to the ErIII ion. Regarding to 3Yb, luminescence was observed in both visible and NIR regions suggesting a partial energy transfer from the ligand to YbIII ion. Dielectric and piezoelectric measurements were performed on single crystals of 3Yb, which confirmed the presence of high dielectric anisotropy and weak piezoelectric response. [ABSTRACT FROM AUTHOR]

Three mononuclear, dinuclear and one-dimensional dysprosium(III) complexes based on 3-azotriazolyl-2,6-dihydroxybenzoic acid (H4ATB) of [Dy(H3ATB)3]·3H2O (1), [Dy2(H2ATB)2(H2DHB)2(H2O)4]·2CH3CN·5H2O (2), and [Dy2(H2ATB)2(DCB)(DMF)2(H2O)2]·4DMF (3) were synthesized and structurally characterized by X-ray single crystal diffraction (H3DHB = 2,6-dihydroxybenzoic acid, H2DCB = 1,4-dicarboxybenzene). Complex 1 was used as a precursor to synthesize complexes 2 and 3, and 2 was further used to synthesize 3. Complex 1 is a mononuclear complex, in which the Dy(III) ion is in a nine-coordinated structure surrounded by three tridentate chelate H3ATB− ligands. Complex 2 displays a dinuclear structure bridged by two μ2 carboxyl groups of two H2DHB− ligands and two μ1,1-O atoms from the phenolic hydroxyl groups of two H2ATB2− ligands. Complex 3 shows a one-dimensional structure formed by two bridging DCB2− ligands. The magnetic measurements were performed on three complexes 1–3, and they showed different magnetic behavior. Complex 1 shows a field-induced slow magnetic relaxation. Complexes 2 and 3 display distinct slow magnetic relaxation under zero dc field with energy barriers (Ueff) of 26(2) cm−1 and 11(1) cm−1, respectively. The magnetic behavior of three complexes 1–3 was investigated by ab initio calculations. [ABSTRACT FROM AUTHOR]

Three mononuclear Co(II) complexes with the compositions of [Co(L1)2] (1), [Co(L2)2(CH3CN)] (2) and [Co(L3)2] (3) (HL1 = 2-((E)-(2-fluorobenzylimino)methyl)-4,6-dibromophenol, HL2 = 2-((E)-(3-fluorobenzylimino)methyl)-4,6-dibromophenol and HL3 = 2-((E)-(4-fluorobenzylimino)methyl)-4,6-dibromophenol) were prepared and structurally determined. The changes in the F-positions in the ligands and solvents led to the formation of these products with various coordination geometries. Both complexes 1 and 3 are four-coordinated and their coordination geometries can be described as tetrahedron and seesaw, whereas complex 2 is five coordinated with a coordination configuration in between trigonal bipyramid and square pyramid. Static magnetic studies reveal that all these complexes exhibit considerable easy-axis magnetic anisotropy. The easy-axis magnetic anisotropy of 1 and 3 mainly derives from the first quartet excited state, whereas that of 2 primarily originates from the first, third and fourth quartet excited states established by theoretical calculations. All the resulting complexes display field-induced slow magnetic relaxation. Complex 3 represents the first Co(II) single ion magnet with a seesaw coordination geometry. Ab initio calculations predict that the magnetic anisotropy will enhance when the seesaw coordination geometry varies from distortion to regulation. [ABSTRACT FROM AUTHOR]

A dinuclear dysprosium cluster [Dy2(NO3)4(H2O)2(L)2]·2CH3CN was successfully prepared by employing HL (HL = 2,6-dimethoxyphenol) and Dy(NO3)3·6H2O in a mixture of CH3OH and CH3CN. The conversion of this Dy2 compound by reaction with additional deprotonated ligand generated a Dy9 cluster [Dy9(μ4-OH)2(μ3-OH)8(μ2-OCH3)4(NO3)8(H2O)8(L)4](OH)·2H2O with the well-known "diabolo" topology. Magnetic investigation revealed that both of the clusters exhibit typical SMM characteristics, and variable magnetic relaxation with the energy barrier changing from 217.87 K to 9.24 K along with the transition from a dinuclear dysprosium cluster to a nonanuclear one. Ab initio calculations further confirm the corresponding structure–activity relationships that originate the different magnetic behaviours. This design may afford a feasible strategy for modulating the magnetic relaxation dynamics of polynuclear systems. [ABSTRACT FROM AUTHOR]

Three mononuclear tetrakis(pseudohalido)-cobalt(II) complexes (Ph4P)2[Co(E)4] (E = N3−, 1; NCO−, 2; NCS−, 3) have been synthesized and structurally characterized. Each compound contains a distorted tetrahedral Co2+ ion coordinated by four pseudohalide ligands. The magnetic properties of 1–3 have been studied using direct-current magnetic measurements and high-frequency and -field EPR spectroscopy (HFEPR), suggesting easy-axis magnetic anisotropy for 1 and 2 and easy-plane anisotropy for 3. Analysis of the HFEPR spectra yielded D values of −5.23 and +3.63 cm−1 for 2 and 3, respectively. The absence of the EPR signal in 1 is consistent with a large, negative value of the zero-field splitting (ZFS) parameter D in 1. The nature of magnetic anisotropies of 1–3 has also been confirmed by ab initio calculations. The calculated D values are consistent with those determined using magnetometry and HFEPR studies. Alternating current (AC) magnetic susceptibilities reveal slow magnetic relaxation under an applied magnetic field, thus indicating that 1–3 are field-induced single-ion magnets (SIMs). [ABSTRACT FROM AUTHOR]

Controllable synthesis of uniformly distributed nanowires of coordination polymers with inherent physical functions is highly desirable but challenging. In particular, the combination of chirality and magnetism into nanowires has potential applications in multifunctional materials and spintronic devices. Herein, we report four pairs of enantiopure coordination polymers with formulae S‐, R‐Dy(cyampH)3 ⋅ CH3COOH ⋅ 2H2O (S‐1, R‐1), S‐, R‐Dy(cyampH)3 ⋅ 3H2O (S‐2, R‐2), S‐, R‐Dy(cyampH)2(C2H5COO) ⋅ 3H2O (S‐3, R‐3) and S‐, R‐Dy(cyampH)3 ⋅ 0.5C2H5COOH ⋅ 2H2O (S‐4, R‐4) [cyampH2=S‐, R‐(1‐cyclohexylethyl)aminomethylphosphonic acids], which were obtained depending on the pH of the reaction mixtures and the specific carboxylic acid used as pH regulator. Interestingly, compounds 3 were obtained as superlong nanowires, showing 1D neutral chain structure which contains both phosphonate and propionate anion ligands. While compounds 1, 2 and 4 appeared as block‐like crystals, superhelices and nanorods, respectively, and exhibited similar neutral chain structures containing only phosphonate ligand. Slow magnetization relaxation characteristic of single‐molecule magnet (SMM) behavior was observed for compounds S‐1 and S‐3. Theoretical calculations were performed to rationalize the magneto‐structural relationships. [ABSTRACT FROM AUTHOR]

A β-diketonate mononuclear dysprosium complex, with the formula [Dy(dpq)(BTFA)3] (1), has been prepared via self-assembly between 3-benzoyl-1,1,1-trifluoroacetone (BTFA) and dipyrido [3,2-d:2′,3′-f]quinoxaline (dpq) ligands. The crystallographic data reveal that the central Dy(III) ion is eight-coordinated by six oxygen atoms from three BTFA ligands and two N atoms from auxiliary dpq ligands, forming an approximately square-antiprismatic (SAP) coordination geometry with a D4d axial symmetry. Magnetic measurements point out that complex 1 exhibits single-molecule magnet (SMM) behaviours with an anisotropy barrier of 45.65 K under a zero direct-current (dc) field. With an applied dc field of 1200 Oe, the quantum tunnelling of the magnetization (QTM) is suppressed in 1 with an enhanced effective barrier of 178.42 K. A diamagnetic Y(III) analogue [Y(dpq)(BTFA)3] (2) and diluted species [Dy0.06Y0.94(BTFA)3(dpq)] (1@Y) were constructed to further perform the dilution experiment. The results unveil that the SMM behaviour observed in 1 is of molecular origin and is related to the single-ion magnetic behaviour of Dy(III) itself, even though the elimination of the dipolar and intermolecular interactions can modestly slow down the magnetic relaxation rate. The relaxation mechanisms and magneto-structure relationship are rationally discussed by ab initio calculations as well. [ABSTRACT FROM AUTHOR]

A family of cyano-bridged 3d–4f 1D chain compounds, {RE[TM(CN)6(2-PNO)5]}·(H2O)4 {RE = YIII, TM = [FeIII]LS (1); RE = DyIII, TM = CoIII (3); RE = ErIII, TM = [FeIII]LS (4), CoIII (5); 2-PNO = 2-picoline-N-oxide} and {RE[TM(CN)6(2-PNO)5]} {RE = DyIII, TM = [FeIII]LS (2)}, were synthesized and characterized. Single-crystal X-ray diffraction studies reveal that compounds 1 and 3–5 are isostructural, while compound 2 has a similar 1D chain structure with a different chain to chain arrangement. An axially-elongated pentagonal bipyramidal (D5h) coordination geometry is formed with five 2-PNO ligands in the equatorial plane and two [TM(CN)6]3− on the apical sites around the rare earth ions in these compounds. A comparison of the magnetic relaxation behaviour in detail reveals that it is more favorable for the Er (4 and 5) than the Dy analogues (2 and 3) to exhibit SIM properties in this axially-elongated D5h coordination environment. Under zero dc field, ac susceptibility measurements show that the Dy analogues have no magnetic relaxation behaviour, while the Er analogues exhibit frequency dependence despite the strong QTM effect. Under a 1 kOe dc field, the Er analogues generally show 1–2 orders of magnitude longer relaxation time at each selected temperature and a higher relaxation energy barrier than the Dy analogues. And the RECo compounds (3 and 5) show a more suppressed QTM effect than the corresponding REFe (2 and 4) compounds, which may be ascribed to the elimination of the fluctuation field from the neighbouring [FeIII]LS ions. The ab initio calculations indicate the misplacement between the orientation of the main magnetic axis and the structural axis in the Dy analogues, and the relative consistency in the Er analogues, which should be the source of the Er analogues showing better SIM properties than the Dy analogues. [ABSTRACT FROM AUTHOR]

The magnetic properties of five DyIII-MII 3d-4f complexes (M = Mn, Fe, Co, Ni and Zn) were studied in detail by comparison due to the same molecule construction. The DyIII-MII assemble (M = Mn, Fe and Ni) behave as field-induced SMMs resulting from the ferromagnetic coupling between DyIII and MII ions, while DyIII-ZnII is SIM and DyIII-CoII does not show the magnetic relaxation. [Display omitted] • In this paper, A series of DyIII-MII 3d-4f complexes (M = Mn, Fe, Co, Ni and Zn) were synthesized. • Their magnetic properties were compared by the magnetostructural correlation. • The coupling between DyIII and MII ions (M = Mn, Fe and Ni) is ferromagnetic. Four Dy-based 3d-4f complexes [MIIDyIII(H 2 L)(NO 3) 3 ](CH 3 OH) 2 (H 4 L = N , N' , N'' , N''' -tetra(2-hydroxy-3-methoxy-5-methylbenzyl)-1,4,7,10-tetraazacyclododecane, M = Mn (2), Fe (3), Co (4) and Ni (5), the solvent of compound 5 is uncertain) were synthesized through the reference method of complex [ZnIILnIII(H 2 L)(NO 3) 3 ](CH 3 OH) 2 (1). The magnetic properties of all the five complexes were measured for comparison. The magnetic results show that all the complexes except 4 behave as single-molecule magnets (SMMs). The magnetostructural analysis and theoretical calculation indicate the ferromagnetic coupling in 2 , 3 and 5 as well as the antiferromagnetic coupling in 4 between DyIII and transition metal ions, while the SMM properties of 1 are caused by the anisotropy of single DyIII ions only. Unexpectedly, neither of the magnetic anisotropic ions in one molecule, namely DyIII and CoII, provides greater advantages for SMM performance. This investigation experimentally proves that the coexistence of magnetic anisotropy of lanthanide ions and ferromagnetic coupling between lanthanide and transition metal ions is important for the design of 3d-4f SMMs. [ABSTRACT FROM AUTHOR]

• Two trinuclear compounds 1 and 2 were synthesized and characterized. • Antiferromagnetic interactions were determined in compound 2. • Complex 1 displays field-induced single-molecule magnet (SMM) behavior. Two trinuclear complexes of formulae [Dy 3 (µ 3- H 2 O)(hmp) 3 (CH 3 COO) 3 ] (1) and [Gd 3 (µ 3 -H 2 O)(hmp) 3 (CH 3 COO) 3 ] (2) were synthesized by employing Dy(CH 3 COO) 3 ·6H 2 O and Gd(CH 3 COO) 3 ·6H 2 O as lanthanide sources and a Schiff-base H 2 hmp (H 2 hmp = 2-(((2-hydroxy-3-methoxybenzyl)imino)methyl)-5-methoxyphenol) as a ligand. Single crystal X-ray diffraction analyses reveal that compounds 1 and 2 are isostructural. The three LnIII ions are bridged by three doubly-deprotonated Schiff-base ligands hmp2−, three acetate ions and one µ 3 -H 2 O molecule, forming a regular triangle structure (Ln...Ln...Ln angles of 60°, and Ln...Ln distances of 3.812 Å for 1 , and 3.838 Å for 2). Magnetic property studies for 1 and 2 indicate that complex 1 displays field-induced single-molecule magnet (SMM) behavior, and there are weak antiferromagnetic interactions among three GdIII ions in complex 2. The main magnetic axes on DyⅢ ions of 1 are calculated by complete-active-space self-consistent field (CASSCF) calculations. Two complexes [Dy 3 (µ 3- H 2 O)(hmp) 3 (CH 3 COO) 3 ] (1) and [Gd 3 (µ 3 -H 2 O)(hmp) 3 (CH 3 COO) 3 ] (2) were synthesized and characterized. Compound 1 displays field-induced single-molecule magnet (SMM) behavior. [Display omitted] [ABSTRACT FROM AUTHOR]

By modulating the substitution on the oxamide ligand, a mononuclear tetrahedral Co(II) complex (HNEt 3) 2 [CoL 2 ] (1) (H 2 L = N , N ′-bis(methanesulfonyl)oxamide) with subtle variation in the CoN 4 coordination environment was successfully synthesized, which displays zero-field slow magnetic relaxation and a hysteresis loop at 1.8 ​K. The complex adopts distorted tetrahedral coordination geometries with acute N–Co–N bite angle imposed by two mutually perpendicular oxamide ligands. Magnetic studies and computational results reveal that the acute N–Co–N bite angle seems to govern the overall magnetic anisotropy of tetrahedral Co(II) complexes with two bidentate chelated ligands containing N 4 -donor set. Upon reducing the bite angle, the D parameter increases gradually and reaches the maximum at about 81°, and then show a significant decrease as the angle continuing to decline. This research demonstrates that the easy-axial magnetic anisotropy can be maximized by reducing the bite angle to a certain extent, which is also feasible for tetrahedral cases with other donor sets. Magnetic studies and theoretical calculations indicate the D value of tetrahedral Co(II) complexes can be increased by appropriately reducing the bite angle of N-Co-N. [Display omitted] • A tetrahedral Co(II) complex with CoN 4 coordination environment was successfully synthesized. • The complex displays zero-field slow magnetic relaxation and a hysteresis loop at 1.8 K. • Magnetic and computational studies reveal that the N-Co-N bite angle seems to govern the overall magnetic anisotropy. • The D value of tetrahedral Co(II) complexes can be maximized by reducing the N-Co-N bite angle to a certain extent. [ABSTRACT FROM AUTHOR]

The complexes of lanthanide metals, especially dysprosium, can generally exhibit excellent magnetic properties. By means of modifying ligands, dual functions or even multi-functions can be achieved. Here, we synthesized an eight-coordinate Dy(III) complex 1, [Dy(HL-o)2(MeOH)2](ClO4)3·4.5MeOH, which is single-molecule magnet (SMM), and the introduction of the rhodamine 6G chromophore in the ring-opened ligand HL-o realizes ligand-centered fluorescence in addition to SMM. Magnetic measurements and ab initio calculations indicate that the magnetic relaxation for complex 1 should be due to the Raman relaxation process. Studies on magneto-structural correlationship of the rhodamine salicylaldehyde hydrazone Dy(III) complexes show that the calculated energy of the first Kramers Doublet (EKD1) is basically related to the Ophenoxy-Dy-Ophenoxy bond angle, i.e., the larger Ophenoxy-Dy-Ophenoxy bond angle corresponds to a larger EKD1. [ABSTRACT FROM AUTHOR]