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A one-dimensional inorganic organic hybrid niobium oxyfluoride undergoes a reversible phase transition and exhibits a switchable dielectric behavior.

A centrosymmetric dinuclear Dy-based complex, Dy2L2(H2L)Cl2(EtOH)2, was successfully synthesised, and exhibits a typical SIM behaviour and unusual triple relaxation pathways.

The synthesis and structural, electrochemical, spectroscopic, and magnetic characterizations of CrIII(HMC) catecholate and semiquinonate complexes are reported herein, where HMC is 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane. cis-[Cr(HMC)(Cat)]+ complexes (Cat = catecholate, [1]+; tetrachlorocatecholate, [2]+; and 3,5-di-tert-butylcatecholate, [3]+) were prepared from the reaction between appropriate catechol and [CrIII(HMC)Cl2]Cl reduced in situ by zinc. Chemical oxidation of [3]+ by FcPF6 resulted in cis-[Cr(HMC)(SQ)]2+ ([3]2+, SQ = 3,5-di-tert-butylsemiquinonate). Single crystal X-ray diffraction studies revealed the cis-chelation of the Cat/SQ ligand around the Cr metal center and confirmed the Cat/SQ nature of the ligands. Reversible oxidations of Cat to SQ were observed in the cyclic voltammograms of [1]+-[3]+, while the CrIII center remains redox inactive. The absorption spectrum of the SQ complex [3]2+ exhibits an intense spin-forbidden transition in solution. Time-delayed phosphorescence spectra recorded at 77 K revealed that all catecholate complexes emit from the 2E state, while [2]+ also emits from the 2T1 state. Temperature-dependent magnetic susceptibility measurements indicate the Cat complexes exist as S = 3/2 systems, while the SQ complex behaves as an S = 1 system, resulting from strong antiferromagnetic coupling of the S = 3/2 Cr center with the S = 1/2 SQ radical. Density functional theory (DFT) shows the similarities between the SOMOs of [1]+ and [2]+ and differences in their LUMOs in the ground state.

Manganese(II) acetate was reacted with indane-1,2,3-trione-1,2-dioxime (H2L), producing three new MnIII complexes containing a MnIII3O unit. Complex 1 is a zero-dimensional (0D) trinuclear manganese(III) cluster. Complexes 2 and 3 show different two-dimensional (2D) structures with their trinuclear manganese(III) units bridged through Na(I) ions. A study of the magnetic properties manifests that antiferromagnetic coupling is clearly dominant in complexes 1 and 2. In contrast, complex 3 is a single-molecule magnet with dominant ferromagnetic couplings between its metal ions. The Na(I) ions adjust the topologies of these complexes, which thus tunes the magnetic-related parameters such as the Mn–O–N–Mn dihedral angle and finally leads to the achievement of single-molecule magnets.

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

The hybrid rare-earth double perovskite (HREDP) system provides great convenience for the construction of multifunctional materials. However, suffering from the high symmetry of their intrinsic structure, HREDPs face the challenges in the realization and optimization of ferroelectric and piezoelectric properties. For the first time, after a systematic investigation of the chirality transformation principle, it is found that the introduction of chirality is an efficient strategy for the targeted construction of multifunctionality, which simultaneously increases the possibility of obtaining multiaxial ferroelectricity and ferroelasticity, and effectively realizes a large piezoelectric response. Moreover, chirality induced ferroelasticity will also achieve excellent magnetic or optical response driven by pressure-sensitive. To verify the feasibility of the above ideas, by using rare-earth ions (Ce

The lanthanide complexes [Cp*2Ln][N,N′-bpyB] (1: Ln = Dy; 3: Ln = Gd; Cp* = pentamethylcyclopentadienyl) and [222-cryptand-K][(Cp*2Ln)(N,N′-bpyB)] (2: Ln = Dy; 4: Ln = Gd) bearing the redox-noninno...

Due to the intriguing chemical variability and structure-property flexibility, molecular materials with striking multifunctional characteristics, including tunable physical, chemical, optical, and electronic properties, have aroused wide attention. Recently, great advances have also been made in designing molecular ferroelastics with optoelectronic properties. However, the band gaps of the most typical ferroelastics are far in excess of 2.0 eV, which severely hinder their further applications. And this corresponds to the inherent incompatibility of ferroelastics. Herein we report an organometallic compound, ferrocenium tetrachloroferrate (

A pentanuclear heterometallic complex [MnIII4DyIII(HL)4{(py)2CO2}2Cl2](OH) (1, H3L = 2-((2-hydroxybenzylidene)amino)propane-1,3-diol, (py)2C(OH)2 = the gem-diol form of 2,2′-dipyridyl ketone) and a one-dimensional (1D) chain [Mn2Dy(HL)2(hmp)2(CH3COO)2N3]n·H2O (2, Hhmp = 2-pyridinemethanol) were obtained by the assemblies of the H3L ligand and Dy(NO3)3·5H2O with MnCl2·4H2O and 2,2′-dipyridyl ketone or with manganese acetate and 2-pyridinemethanol under different alkaline solutions. In 1, four MnIII ions formed an irregular tetrahedron, in which four MnIII ions were linked with the central DyIII by eight O atoms from HL2− or from (py)2CO22− ligands. In 2, one DyIII and two MnIII formed a [Mn2Dy] unit, in which the metal ions were bridged by one N3− ion and by four O atoms of two HL2− and two hmp− ligands, and then these [Mn2Dy] units were further linked by the O atoms from HL2− ligands and formed a 1D zigzag chain. Magnetic studies indicated that both complexes exhibit slow relaxation behavior, with the effective energy barriers of 7.9 K and 9.6(0) K for 1 and 2, respectively, which might represent new members for the rarely polynuclear Mn–Dy single molecule magnets. The orientations of the easy magnetization axes of DyIII ions in 1 and 2 were estimated by the Magellan program, indicating that the easy axes of DyIII in 1 are nearly directed to C16 and C47 from (py)2CO22− ligands, while the axis in 2 is almost directed to O5 (from the acetate ligand).

The effect of screening the CoII moment of monomeric [CoIIL2(H2O)] (L = 8-hydroxyquinaldine), having a trigonal bipyramid coordination, by diamagnetic Zn in CoxZn1−x solid solutions on its magnetic relaxation was explored using ac-susceptibility, high-field electron–spin-resonance measurements and CASPT2 calculations. The retention of the crystal structure for all the solid solutions was demonstrated using single crystal diffraction. The dc-magnetization and theoretical fittings of the susceptibility for Co1 and Co0.1Zn0.9 gave a large zero-field-splitting (ZFS) D of 50 ± 6 cm−1, and very weak dipole interaction between the nearest neighbors, while EPR and calculations confirmed the positive sign of the axial component (D). Consistent parameters were obtained from experiments and theory. Importantly, only field-induced relaxation was observed for the samples with less than 50% Co and a gradual change in the barrier energy to moment reversal and relaxation times was observed between 11% and 20% Co, while both were enhanced for higher dilutions. The results establish a clear barrier for extending the longevity of the magnetism for this type of single-ion species by lowering the intramolecular interactions. The results suggest that the magnetic interaction persists up to the second sphere, that is, for a dilution of 1 in 9 (11% Co). Importantly, this method is applicable to all single-ion magnet systems, that is, the optimum dilution concentration to restrain the dipole field can be given only by the single crystal structure.

In this work, we first synthesized a Zn-Dy complex, [Zn6Dy2(L)6(tea)2(CH3OH)2]·6CH3OH·8H2O (H2L = N-3-methoxysalicylidene-2-amino-3-hydroxypyridine, teaH3 = triethanolamine, 1), by employing H2L, anhydrous ZnCl2, and Dy(NO3)3·5H2O reacting with auxiliary ligand teaH3 in the mixture of CH3OH and DMF. When teaH3 and the solvent CH3OH in the reaction system of 1 were replaced by the auxiliary ligand 2,6-pyridinedimethanol (pdmH2) and the solvent MeCN, another Zn-Dy complex, [Zn4Dy4(L)6(pdm)2(pdmH)4]·10CH3CN·5H2O (2), was obtained. For 1, its crystal structure can be viewed as a dimer of two Zn3DyIII units. However, for 2, four DyIII form a zigzag arrangement, and each of its terminals linked two ZnII ions. Interestingly, although the structural topologies of 1 and 2 are different, the coordination geometries of DyIII in 1 and 2 are all triangular dodecahedron (TDD-8). The difference is that the continuous shape measure (CShM) values of DyIII in 1 are larger than the corresponding values in 2. Magnetic investigation revealed that the diluted sample 1@Y exhibits two magnetic relaxation processes, while 2 only exhibits a single relaxation process. Ab initio calculations indicated that, in the crystal lattice of 1, two complexes exhibiting slightly different CShM values of DyIII result in the double relaxation behavior of 1@Y. However, for 2, one of two DyIII fragments possesses a fast quantum tunneling of magnetization (QTM), resulting in its magnetic process presented at T < 1.8 K, so 2 exhibits single relaxation behavior. More importantly, the theoretical calculations also clearly indicated that the weak ligation at equatorial sites of DyIII in 1 and 2 ensure 1@Y and 2 possess SMM behavior, although the coordination geometry of DyIII (TDD-8) in 1 and 2 severely deviates from the ideal polyhedron and its axial symmetry is low.

A new Dy Na complex [DyIIINaI(CH3CO2)2(DMF)3(H6C8A)]·4DMF (1, DMF = N,N-dimethylformamide, H8C8A = p-tert-butylcalix[8]arene) was obtained and it was characterized by elemental analyses, IR spectroscopy, single-crystal X-ray diffraction analyses, PXRD and magnetic properties. In 1, one DyIII and one NaIII were linked by two O atoms from two CH3CO2− and the two metal ions were enclosed into a H8C8A. The remaining coordination sites of the DyIII and NaI ions were occupied by three O atoms from three DMF coordinated molecules. The DyIII ion in 1 adopts eight coordinate with a triangular dodecahedron. Magnetic property studies indicated complex 1 show slow magnetic relaxation behavior under 1000 Oe applied dc field. Additionally, the orientation of the anisotropy axis for the DyIII in 1 was estimated by Magellan program and the anisotropic axis is aligned along Dy1-O2 bond with an angle of 12.608°.

Polyoxovanadates (III) are important class of polyoxometalates in molecular magnetism field, and particularly the systems which contain vanadium(III) centers. To date, only very few highly reduced vanadium polynuclear complexes were reported, which remains a significant challenge to synthesize novel polyoxovanadates, owing to the characteristics of easily oxidized vanadium(III). Herein, two unprecedented petaloid chiral octanuclear polyoxovanadates, l- and d-[H2N(CH3)2]12.5(H3N(CH2)2NH3)(H3O)1.5(VIIIμ2-OH)8(SO4)16·2H2O (L-, D-V8), have been successfully obtained by solvothermal method without any chiral auxiliary. Both L- and D-V8 compounds contain the motif eight-membered ring (Vμ2-O)8(SO4)16 constituted of three different chiral entangled loops with the V atoms as nodes. Bond valence calculation (BVC) analysis indicates that all the V ions existed in L, D-V8 are +3 value. The magnetic behavior of compounds indicated ferromagnetic coupling between vanadium(III) ions. To our knowledge, it is the first chi...

A brand new europium(iii) β-diketonate complex undergoes a single-crystal-to-single-crystal transformation via [2+2] cycloaddition after UV irradiation, triggering strong Eu(iii) red emission turn-on, which is highly photostable even after 50 hours of irradiation. A photo-patterning process is successfully conducted for security printing application in materials science.

Four chair-like hexanuclear Fe-Ln complexes containing mixed organic ligands, namely, [Fe4Ln2{(py)2CO2}4(pdm)2(NO3)2(H2O)2Cl4]·xCH3CN·yH2O (Ln = GdIII (1, x = 1, y = 0), DyIII (2, x = 1, y = 1), HoIII (3, x = 0, y = 2), and ErIII (4, x = 1, y = 3); (py)2CO2H2 = the gem-diol form of di-2-pyridyl ketone and pdmH2 = 2,6-pyridinedimethanol) have been obtained by employing di-2-pyridyl ketone and 2,6-pyridinedimethanol reacting with FeCl3 and Ln(NO3)3 in MeCN. The structures of 1-4 are similar to each other except for the number of lattice solvent molecules. Four FeIII and two LnIII in these complexes comprise a chair-like core with the "body" constructed by four FeIII ions and the "end" constructed by two LnIII ions. Among the four compounds, 2 shows field-induced single molecule magnet behavior as revealed by ac magnetic susceptibility studies, with the effective energy barrier and the pre-exponential factor of 22.07 K and 8.44 × 10-7 s, respectively. Ab initio calculations indicated that, among 2_Dy, 3_Ho and 4_Er fragments, the energy gap between the lowest two spin-orbit states for 2_Dy is the largest, while the tunneling gap for 2 is the smallest. These might be the reasons for complex 2 exhibiting SMM behavior. Additionally, the orientations of the magnetic anisotropy of DyIII in 2 were obtained by electrostatic calculations and ab initio calculations, both indicating that the directions of the main magnetic axis of Dy1 ions are almost aligned along Dy1-O5 (O5 from the pdm2- ligand).

In this work, we report the syntheses, crystal structures and magnetic properties of three novel Zn–Ln mixed metal complexes, namely [Zn4Dy2(L1)2(L2)2(N3)2]Cl2·2H2O (1), [Zn4Tb2(L1)2(L2)2(Cl)2][ZnN3Cl3]·2H2O (2), and [Zn4Gd2(L1)2(L2)2(Cl)2][ZnN3Cl3]·2H2O (3), in which L12− and L23− were formed from the ligand L [L = N1,N3-bis(3-methoxysalicylidene)diethylenetriamine] through in situ reactions. Interestingly, carbon dioxide in air was absorbed in the process of forming carbamate ligand L23−; this can be ascribed to the insertion of CO2 into M–N amide bonds. Moreover, 1 and 2 represent the first series of 3d–4f SMMs containing carbamate ligands by fixation of CO2 in air. Single-crystal X-ray diffraction analyses reveal that the crystal structures of 1 and 2 are anion-dependent, i.e., the apical positions of the two ZnII ions in 1 and 2 are occupied by an N atom of N3− and by Cl−, respectively. However, the topologies of 2 and 3 are similar. Two ZnII ions and one LnIII (Ln = Dy (1), Tb (2) and Gd (3)) form nearly linear trinuclear [Zn2Ln] units which are double-bridged by two L23− ligands. Magnetic studies reveal that two complexes show single molecule magnet behavior under a direct current (dc) field, with effective energy barriers (Ueff) of 30.66(5) K for 1 and 8.87(3) K for 2. Ab initio calculations reveal that the DyIII ions in 1 and the TbIII ions in 2 are axial in nature; however, a difference in the tunnel splitting of 1 and 2 leads to variation in the magnetization blockades of the two complexes. Theoretical calculations also indicate that the directions of the main magnetic axes severely deviate from the coordination atoms of the first spheres of DyIII and TbIII in 1 and 2; thus further results in poor SMM behavior of the two complexes.

To modulate the molecular symmetry of tetrahedral Dy4 complexes, in this paper, we reported two complexes based on a Dy4 or Dy2Fe2 tetrahedral unit, namely, [Dy4(NO3)(HL)4{(py)2C(OH)O}2](OH)·6CH3CN·0.5H2O (1, H3L = 2-((2-hydroxybenzylidene)amino) propane-1,3-diol, (py)2C(OH)2 = the gem-diol form of di-2-pyridyl ketone) and [Fe4Dy2(μ4-O)(HL)3{(py)2CO2}{(py)2C(OH)O}{(py)2C(OCH3)O}(L′)Cl3]Cl·6CH3CN·3.5H2O (2, H2L′ = 2-amino-1,3-propanediol). In 1, each of the four sides of the Dy4 tetrahedron was constructed from one O atom of one (py)2C(OH)O− ligand and one O atom of one HL12− ligand, one side was constructed from two O atoms of two (py)2C(OH)O− ligands, and the remaining side was not constructed from organic ligands. Consequently, NO3− in 1 adopts an unprecedented η4, η1, η1, μ4 coordination mode, in which one O atom (O17) linked with four DyIII and each of another two O atoms further coordinated with a DyIII ion. For 2, the tetrahedral unit was composed of two DyIII ions and two FeIII ions, and each of the two DyIII ions is further linked with an FeIII ion. Slow relaxation behavior was observed for both complexes, with an energy barrier of 8.73 K for 1 under a zero dc field and 13.80 K for 2 under a 1500 Oe dc field, respectively. The orientations of the magnetic anisotropy of DyIII in 1 and 2 were calculated by the Magellan program, indicating that the easy magnetization axes of the four DyIII ions in 1 were not directed to O17, while the axes in 2 are nearly parallel to each other.

In this paper, we present the synthesis, crystal structures and magnetic properties of three complexes with formulae [Cu3Ln2(L)2(teaH)2(N3)2Cl2]·xCH3CN (H2L = N1,N3-bis(3-methoxysalicylidene)diethylenetriamine, teaH3 = triethanolamine; Ln = Ho, x = 3 for 1, Ln = Dy, x = 2 for 2 and Ln = Gd, x = 3 for 3), and the structural topologies of 1–3 are unprecedented. The structural analyses revealed that the metal ions in 1–3 formed a kite-like topology with Ln1, Ln2 and Cu1 located on the body, while Cu2 and Cu3 located on both wings. The dc data of 3 were fitted, which showed that the magnetic couplings are antiferromagnetic between CuII and between GdIII ions, while they are ferromagnetic between CuII and GdIII ions. AC magnetic susceptibility studies for 1 and 2 indicated that both complexes exhibit frequency dependent χ′′ signals at low temperature, but no χ′′ peaks were observed, which may be due to the deviation from ideal geometry for HoIII in 1 and DyIII in 2 and the presence of weak magnetic couplings between paramagnetic ions within the two complexes. For 3, the ac magnetic susceptibilities with zero dc fields show no frequency dependent χ′′ signals because of the isotropy of GdIII. The orientation of the easy magnetization axes of two DyIII in 2 was estimated using the Magellan program, indicating that the magnetic anisotropy axes for Dy1 and Dy2 are almost perpendicular with the angle of 86.630°.

Four tetranuclear 3d–4f complexes, namely [Fe2Ln2(L)2(teaH)2(Cl)2](NO3)2·4CH3CN (H2L = N1,N3-bis(3-methoxysalicylidene)diethylenetriamine, teaH3 = triethanolamine, Ln = Dy for 1 and Ln = Gd for 1′) and [Co2Ln2(L)2(pdm)2(CH3COO)2(CH3OH)2](NO3)2·xCH3OH·yH2O (pdmH2 = 2,6-pyridinedimethanol, Ln = Dy, x = 5 and y = 2.5 for 2 and Ln = Gd, x = 6 and y = 1.5 for 2′), have been reported. Two FeIII and two DyIII in 1 formed a zigzag Fe1–Dy1–Dy1a–Fe1a arrangement with a Fe1–Dy1–Dy1a angle of 105.328(3)°. However, in contrast to 1, two CoIII and two DyIII ions in 2 formed a more linear Co1–Dy1–Dy1a–Co1a arrangement with a Co1–Dy1–Dy1a angle of 141.86(2)°. Additionally, two DyIII ions in 1 are eight-coordinated with a triangular dodecahedron geometry, while two DyIII ions in 2 adopt nine-coordination with a muffin geometry. Magnetic studies revealed slow magnetic relaxation behavior for 1, with an energy barrier Ea of 6.9 K. For 2, single molecule magnet behavior was presented under a zero dc field with an effective energy barrier Ueff of 64.0(9) K. Ab initio calculations for 1 and 2 indicate that compared to 2, complex 1 has a larger transversal magnetic moment of its ground Kramers doublets (KD) and a larger value of the tunnelling parameter (Δt) for the exchanged coupled ground state, which may result in poor single molecule magnet behavior for 1.

A novel DyIII-NaI one-dimensional chain, namely [DyIIINaI(L)(CH3CO2)2]n·2CH3CN (1, H2L = N1,N3‑bis(3‑methoxysalicylidene)diethylenetriamine), was synthesized by treating H2L, di-2-pyridyl ketone (dpk), and NaHCO3 with Dy(CH3CO2)2·6H2O in acetonitrile. Complex 1 was characterized by elemental analyses, IR spectroscopy, single-crystal X-ray diffraction analyses and magnetic properties. Structural analyses revealed that 1 consists of a neutral one-dimensional (1D) chain. In each [DyNa] unit, one DyIII and one NaI ions are bridged by two phenoxido O atoms from one L2− ligand and one carboxyl O atom from one CH3CO2−. Moreover, the [DyNa] units were further connected by two carboxyl O atoms from another CH3CO2−. The magnetic studies revealed that 1 exhibits the field-induced single molecule magnet behavior with an effective energy of 13.21 K. The orientation of the anisotropy axes for the DyIII in 1 was estimated by Magellan program, indicating that the directionality of the anisotropic axes is almost collinear to the Dy1-O8 bond, with an angle of 3.085°.

Triplet diradicals have attracted tremendous attention due to their promising application in organic spintronics, organic magnets and spin filters. However, very few examples of triplet diradicals with singlet–triplet energy gaps (ΔEST) over 0.59 kcal mol−1 (298 K) have been reported to date. In this work, we first proved that the dianion of 2,7-di-tert-butyl-pyrene-4,5,9,10-tetraone (2,7-tBu2-PTO) was a triplet ground state diradical in the magnesium complex 1 with a singlet–triplet energy gap ΔEST = 0.94 kcal mol−1 (473 K). This is a rare example of stable diradicals with singlet–triplet energy gaps exceeding the thermal energy at room temperature (298 K). Moreover, the iron analog 2 containing the 2,7-tBu2-PTO diradical dianion was isolated, which was the first single-molecule magnet bridged by a diradical dianion. When 2 was doubly reduced to the dianion salt 2K2, single-molecule magnetism was switched off, highlighting the importance of diradicals in single-molecule magnetism., We report a triplet diradical dianion in magnesium complex with ΔEST = 0.94 kcal mol−1 (473 K). Its iron analog is the first single-molecule magnet bridged by a diradical dianion, and the SMM property is switched off through two-electron reduction.

Five β-diketone based Dy(iii) single-ion magnets (SIMs), [DyIII(TTA)3(AIP)]·0.5CH3CH2OH·0.5H2O (1), [DyIII(TTA)3(APIP)]·2CH3OH·H2O (2), [DyIII(TTA)3(DPP)] (3), [DyIII(TTA)3(BPP)]·0.5CH3CH2OH (4) and [DyIII(TTA)3(AIP)]·1.5H2O (5), were fully synthesized through alteration of their phenanthroline derivates (AIP = 2-(anthracen-9-yl)-1H-imidazo[4,5-f][1,10]phenanthroline, APIP = 2-(4-(anthracen-9-yl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline, DPP = 2,3-diphenylpyrazino[2,3-f][1,10]phenanthroline and BPP = 2,3-bis(2,5-dimethylthiophen-3-yl)pyrazino[2,3-f][1,10]phenanthroline). Magnetic investigations reveal that all the complexes perform as SIMs, with notably different effective barriers of 69.4 K (1), 147.3 K (2), 122.1 K (3) and 234.2 K (4) in zero direct current (dc) field. Complexes of 2 and 4 possess almost twofold higher effective barriers compared to 1 and 3. By analyzing the crystal structures, the distinct magnetic dynamics was found to stem from the variation in intermolecular hydrogen bond interactions and charge delocalization of auxiliary ligands. With the help of ab initio calculations, a change of auxiliary ligand brings about varying intensities of quantum tunnelling magnetization (QTM), which account for the distinguishable magnetic dynamics. With a combination of experimental and theoretical analyses, this work provides a visual and instructive perspective to the understanding of fine tuning auxiliary ligands to design structurally modulated SIMs of mononuclear β-diketone dysprosium(iii) complexes.

We have synthesized a series of transition metal compounds [M(L)2(H2O)2] (M = Co (1), Ni (2), and Cu (3)) by using the 4-amino-1,2,4-triazole Schiff-base ligand via the hydrothermal methods. They are all mononuclear compounds with the octahedral geometry. Direct-current magnetic and HF-EPR measurements were combined to reveal the negative D values (–28.78 cm−1, –10.79 cm−1) of complexes 1 and 2, showing the easy-axis magnetic anisotropies of compounds 1 and 2. Applying a dc field of 800 Oe at 2.0 K, the slow magnetic relaxation effects were observed in compound 1, which is a remarkable feature of single-ion magnets.

Despite wide potential applications of Gd-clusters in magnetocaloric effect (MCE) owing to f7 electron configuration of Gd(III), the structural improvement in order to enhance MCE remains difficult. A new approach of the situ hydrolysis of acetonitrile is reported, and the slow release of small ligand CH3COO– is realized in the design and synthesis of high-nuclearity lanthanide clusters. A large lanthanide-exclusive cluster complex, [Gd60(CO3)8(CH3COO)12(μ2-OH)24(μ3-OH)96(H2O)56](NO3)15Br12(dmp)5·30CH3OH·20Hdmp (1-Gd60), was isolated under solvothermal conditions. To the best our knowledge, cluster 1 possesses the high metal/ligand ratio (magnetic density) and the largest magnetic entropy change (−ΔSmmax = 48.0 J kg–1 K–1 at 2 K for ΔH = 7 T) among previously reported high-nuclearity lanthanide clusters.

DyIII(depma)3(NO3)3 (1) and DyIII(depma)4(NO3)2(CF3SO3) (2) differ structurally by the number of depma ligands and the supramolecular interactions (π-π and C-Hπ, respectively) between anthracene moieties. They exhibit single-ion-magnetism which is coupled to photo- and mechanochromism that are partially reversible by thermal annealing. The changes are associated with the formation and destruction of excimers.

Four chair-like hexanuclear Fe-Ln complexes containing mixed organic ligands, namely, [Fe

Reaction of the diazafluorenylidene-substituted phosphaalkene 1 with [Cp*2Ln][BPh4] (Ln = Dy, Tb, and Gd), followed by subsequent reduction with KC8, afforded complexes Cp*2Dy(N,N′-1) (2), Cp*2Tb(N...

Four tetranuclear 3d-4f complexes, namely [Fe

Polyoxovanadates (III) are important class of polyoxometalates in molecular magnetism field, and particularly the systems which contain vanadium(III) centers. To date, only very few highly reduced vanadium polynuclear complexes were reported, which remains a significant challenge to synthesize novel polyoxovanadates, owing to the characteristics of easily oxidized vanadium(III). Herein, two unprecedented petaloid chiral octanuclear polyoxovanadates, l- and d-[H

The unpredictability of the polyoxometalate (POM) coordination model and the diversity of organic ligands provide more possibilities for the exploration and fabrication of various novel POM-based materials. In this work, a series of POM-based lanthanide (Ln)-Schiff base nanoclusters, [Ln(H2O)2(DAPSC)]2[Ln(H2O)3(DAPSC)]2[(SiW12O40)]3·15H2O (Ln = Sm, 1; Eu, 2; Tb, 3), have been successfully isolated by the reaction of classical Keggin POMs, a Ln3+ ion, and a Schiff-base ligand [2,6-diacetylpyridine bis(semicarbazone), abbreviated as DAPSC]. Both the hindrance effect of the organic ligand and charge balance endow the cluster with fascinating structural features of discrete and linear arrangement. The title compounds with dimensions of ca. 4 × 1 × 1 nm3 are first trimeric polyoxometalate-based nanosized compounds, constructed by saturated POM anions (SiW12O404-, denoted as SiW12). Moreover, the properties (stability, electrochemistry, third-order nonlinear optics, and magnetism) of the compounds have also been studied.

In this work, we report the syntheses, crystal structures and magnetic properties of three novel Zn-Ln mixed metal complexes, namely [Zn4Dy2(L1)2(L2)2(N3)2]Cl2·2H2O (1), [Zn4Tb2(L1)2(L2)2(Cl)2][ZnN3Cl3]·2H2O (2), and [Zn4Gd2(L1)2(L2)2(Cl)2][ZnN3Cl3]·2H2O (3), in which L12- and L23- were formed from the ligand L [L = N1,N3-bis(3-methoxysalicylidene)diethylenetriamine] through in situ reactions. Interestingly, carbon dioxide in air was absorbed in the process of forming carbamate ligand L23-; this can be ascribed to the insertion of CO2 into M-N amide bonds. Moreover, 1 and 2 represent the first series of 3d-4f SMMs containing carbamate ligands by fixation of CO2 in air. Single-crystal X-ray diffraction analyses reveal that the crystal structures of 1 and 2 are anion-dependent, i.e., the apical positions of the two ZnII ions in 1 and 2 are occupied by an N atom of N3- and by Cl-, respectively. However, the topologies of 2 and 3 are similar. Two ZnII ions and one LnIII (Ln = Dy (1), Tb (2) and Gd (3)) form nearly linear trinuclear [Zn2Ln] units which are double-bridged by two L23- ligands. Magnetic studies reveal that two complexes show single molecule magnet behavior under a direct current (dc) field, with effective energy barriers (Ueff) of 30.66(5) K for 1 and 8.87(3) K for 2. Ab initio calculations reveal that the DyIII ions in 1 and the TbIII ions in 2 are axial in nature; however, a difference in the tunnel splitting of 1 and 2 leads to variation in the magnetization blockades of the two complexes. Theoretical calculations also indicate that the directions of the main magnetic axes severely deviate from the coordination atoms of the first spheres of DyIII and TbIII in 1 and 2; thus further results in poor SMM behavior of the two complexes.

A one-dimensional (1D) chain [Cu3(HL)2(N3)(Mtta)]n.0.5CH3CN (1, H3L = 2-((2-hydroxybenzylidene)amino)propane-1,3-diol and Mtta = 5-methyl tetrazolate) and a Cu4Dy2 complex [Cu4Dy2{(py)2CO2}2{(py)2C(OH)O}2(CH3COO)4(N3)4].3CH3CN (2, (py)2C(OH)2 = the gem-diol form of di-2-pyridyl ketone) were obtained by the assemblies of the H3L ligand and Dy(NO3)3·5H2O with copper nitrate or with copper acetate and di-2-pyridyl ketone under the MeCN solution containing triethylamine or containing NaOH. In 1, three CuII ions were linked into a trinuclear Cu unit by three neighboring N atoms of Mtta ligand and two alkoxido-type O atoms from two HL2− ligands, then these units were further linked into a one-dimensional (1D) chain by two phenoxido O atoms from two HL2− ligands. In 2, two CuII and two DyIII ions formed a butterfly-type topology, which was further linked another two CuII by the O atoms from (py)2CO22– or from acetate ligands. Magnetic studies indicated that, in 1, the magnetic coupling through the paths of Cu N N Cu and Cu-Oalkoxido-Cu is antiferromagnetic (J1 = −14.81 cm−1), and its value was first determined in the polynuclear Cu complexes containing Mtta ligand. However, the magnetic coupling through the path of Cu-Ophenoxido-Cu is ferromagnetic (J2 = 24.61 cm−1). Magnetic studies revealed that 1 exhibits slow magnetic relaxation behavior, with an energy barrier Ueff of 6.06 K. The orientations of the easy magnetization axes of DyIII ions in 2 was estimated by Magellan program, indicating that the easy axes of DyIII in 2 are roughly aligned along alkoxido-type O atoms (O3 and O3a), which is slightly longer than other Dy-O distances.

A novel manganese compound with Fe(IV) building block has been synthesized and characterized by single-crystal diffraction analysis, which presents of a 1D staircase chain structure. The adjacent staircase chains are expended into a 2D layer through π-π interaction between the terminal oxalyl groups. Furthermore, the 2D layers are connected to form a 3D supramolecular framework by rich hydrogen bonds. Low-temperature magnetic measurements reveal that intrachain antiferromagnetic couplings dominates through the FeIV-oxamido-MnII pathways, concomitantly with a typical ferrimagnetic behavior.

Despite wide potential applications of Gd-clusters in magnetocaloric effect (MCE) owing to f

Two cobalt complexes with similar structures were synthesized using quinoline-2-carboxylic acid (HL) as the ligand. Both complexes are six-coordinated in antitriangular prism coordination geometries. There are one and four molecule units per cell for 1 and 2, respectively, with nearest Co–Co distances of 7.129 and 5.855 A, respectively, which lead to their intermolecular interactions zj′. Both complexes are field-induced single-ion magnets. Complex 1 shows single slow relaxation under Hdc = 1.5 kOe attributed to the moment reversal, while complex 2 shows double slow relaxation resulting from intermolecular dipolar interaction and moment reversal, respectively.

Si3N4 belts with tunable width were synthesized by regulating the partial pressure of NH3/N2 in gaseous mixtures of Ar and NH3/N2 during the nitridation of silicon powders, which demonstrated tunable photoluminescence properties.

The synthesis of heterostructures with branched morphology is of great importance for exploiting novel physical and chemical properties in nanoscience and nanotechnology fields. In this study, by combining the extended vapor–liquid–solid (EVLS) and vapor–solid (VS) growth methods, we successfully fabricate three-dimensional (3D) AlN–Si3N4 branched heterostructures with the core of Si3N4 nanostructures and branched AlN nanocones with adjustable diameter and length. The photoluminescence (PL) spectra of the AlN–Si3N4 branched heterostructures display new emission bands besides those of the as-synthesized Si3N4 nanostructures, which may be ascribed to the emission bands of AlN in the deep- or trap-level state. From these results we propose a general strategy for designing and preparing 3D branched heterostructures for novel optoelectronic devices.

Highly-ordered boron nitride (BN) nanotube arrays have been synthesized by microwave plasma-enhanced chemical vapor deposition (MW-PECVD) below 520 °C under the confinement of anodic aluminum oxide (AAO) template with borane/argon and ammonia/nitrogen as precursors. The low growth temperature and aligned arrangement of the BN nanotubes are beneficial to practical applications despite of the amorphous nature of the product. Novel morphology of Y-branching and dendriform BN nanotubes were also observed when the branching AAO template was used.