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Controlling spin behavior via external stimuli is a key route to develop molecular spintronics devices. Photons, temperature, pressure, chemicals, and electric field are the possible stimuli. Herei...

Two cobalt oxyfluoride antiferromagnets CoMOF5(pyz)(H2O)2 (M = Nb 1, Ta 2; pyz = pyrazine) have been synthesized via conventional hydrothermal methods and characterized by thermogravimetric (TGA) analysis, FTIR spectroscopy, electron spin resonance (ESR), magnetic susceptibility, and magnetization measurements at both static low field and pulsed high field. The single-crystal X-ray diffraction indicates both compounds 1 and 2 are isostructural and crystallize in the monoclinic space group C2/m with a two-dimensional Co2+ triangular lattice in the ab plane, separated by the nonmagnetic MOF5 (M = Nb 1, Ta 2) octahedra along the c-axis with large intertriangular-lattice Co···Co distance. Because of low dimensionality together with frustrated triangular lattice, compounds 1 and 2 exhibit no long-range antiferromagnetic order until ∼3.7 K. Moreover, a spin flop transition is observed in the magnetization curves at 2 K for both compounds, which is further confirmed by ESR spectra. In addition, the ESR spectra suggest the presence of a zero-field spin gap in both compounds. The high field magnetization measured at 2 K saturates at ∼7 T with Ms = 1.55 μB for 1 and 1.71 μB for 2, respectively, after subtracting the Van Vleck paramagnetic contribution, which is usually observed for Co2+ ions with pseudospin spin of 1/2 at low temperature. Powder-averaged magnetic anisotropy of g = 3.10 for 1 (3.42 for 2) and magnetic superexchange interaction J/kB = -3.2 K for 1 (-3.6 K for 2) are obtained.

Layered heterometallic 5f-3d uranyl phosphonates can exhibit unique luminescent and/or magnetic properties, but the fabrication and properties of their 2D counterparts have not been investigated. Herein we report three heterobimetallic uranyl phosphonates, namely, [(UO

The title compound was studied, which showed relatively large rhombic anisotropy and field-induced slow magnetic relaxation behaviour.

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).

A new frustrated spin-cluster antiferromagnet Sr2Co3(C2O4)3(OH)4·3H2O has been synthesized by the hydrothermal method. The basic magnetic unit of this compound is an isolated Co6 cluster, which is ...

We have successfully synthesized a new transition metal tellurate compound K2Cu2(Te2O5)(TeO3)2·2H2O. The compound crystallizes in the monoclinic crystal system with space group P21/c; the Te coordi...

Strong Mn-Mn coupling interactions (dipole-dipole and spin-exchange), predominantly determined by statistically and apparently short Mn···Mn distances in traditional heavily Mn2+-doped semiconductors, can promote energy transfer within randomly positioned and close-knit Mn2+ pairs. However, the intrinsic mechanism on controlling Mn2+ emission efficiency is still elusive due to the lack of precise structure information on local tetrahedrally coordinated Mn2+ ions. Herein, a group of Mn2+-containing metal-chalcogenide open frameworks (MCOFs), built from [Mn4In16S35] nanoclusters (denoted T4-MnInS) with a precise [Mn4S] configuration and length-variable linkers, were prepared and selected as unique models to address the above-mentioned issues. MCOF-5 and MCOF-6 that contained a symmetrical [Mn4S] core with a D2d point group and relatively long Mn···Mn distance (∼3.9645 A) exhibited obvious red emission, while no room-temperature PL emission was observed in MCOF-7 that contained an asymmetric [Mn4S] configuration with a C1 point group and relatively short Mn···Mn distance (∼3.9204 A). The differences of Mn-Mn dipole-dipole and spin-exchange interactions were verified through transient photoluminescent spectroscopy, electron spin resonance (ESR), and magnetic measurements. Compared to MCOF-5 and MCOF-6 showing a narrower/stronger ESR signal and longer decay lifetime of microseconds, MCOF-7 displayed a much broader/weaker ESR signal and shorter decay lifetime of nanoseconds. The results demonstrated the dominant role of distance-directed Mn-Mn dipole-dipole interactions over symmetry-directed spin-exchange interactions in modulating PL quenching behavior of Mn2+ emission. More importantly, the reported work offers a new pathway to elucidate Mn2+-site-dependent photoluminescence regulation mechanism from the perspective of atomically precise nanoclusters.

Two cobalt oxyfluoride antiferromagnets CoMOF

Two five-coordinate mononuclear Co(ii) complexes [Co(12-TMC)X][B(C6H5)4] (L = 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane (12-TMC), X = Cl- (1), Br- (2)) have been studied by X-ray single crystallography, magnetic measurements, high-frequency and -field EPR (HF-EPR) spectroscopy and theoretical calculations. Both complexes have a distorted square pyramidal geometry with the Co(ii) ion lying above the basal plane constrained by the rigid tetradentate macrocyclic ligand. In contrast to the reported five-coordinate Co(ii) complex [Co(12-TMC)(NCO)][B(C6H5)4] (3) exhibiting easy-axis anisotropy, an easy-plane magnetic anisotropy was found for 1 and 2via the analyses of the direct-current magnetic data and HF-EPR spectroscopy. Frequency- and temperature-dependent alternating-current magnetic susceptibility measurements demonstrated that complexes 1 and 2 show slow magnetic relaxation at an applied dc field. Ab initio calculations were performed to reveal the impact of the terminal ligands on the nature of the magnetic anisotropies of this series of five-coordinate Co(ii) complexes.

A series of mononuclear seven-coordinate Co(ii) complexes [CoII(BPA-TPA)](ClO4)2·H2O (2-ClO4), [CoII(BPA-TPA)](PF6)2 (3-PF6) and [CoII(BPA-TPA)](BPh4)2 (4-BPh4) have been synthesized based on the ligand 2,6-bis(bis(2-pyridylmethyl)amino)methylpyridine (BPA-TPA), and their structures have been characterized by single-crystal X-ray diffraction. All these complexes feature an intermediate coordination polyhedron between a capped trigonal prism and a capped octahedron, which is perturbed by the variation of the counter anions. Easy-plane magnetic anisotropies for all complexes were revealed via the analyses of the direct-current magnetic data and high-field electron paramagnetic resonance (HFEPR) spectra. They show slow magnetic relaxation under applied direct current field, which is similar to the previously reported complex [CoII(BPA-TPA)](BF4)2 (1-BF4) with a capped trigonal prism. This work provides a new example of modulating the properties of single-ion magnets (SIMs) by changing the counter anions.

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.

The solvent-induced topological and structural diversities of two Co(II) complexes, namely, [Co(L)2(SCN)2] (Co1) and [Co2(L)2(SCN)(OAc)3] (Co2) (L = 8-methoxyquinoline), were comparatively analyzed. Certain proportions of L, Co(OAc)2·4H2O, and NaSCN were mixed and dissolved in CH3OH at 60 °C to obtain complex Co1. Complex Co2, an asymmetric dinuclear compound, was obtained by simply replacing CH3OH with CH3CN as the solvent. The Co(II) ion in complex Co1 was coordinated by the N4O2 mode provided by two L ligands and two SCN– anions. The two Co(II) ions in Co2 were in the N2O4 and NO5 coordination environment and were linked by two μ2-OAc– bridges and one rare μ3-OAc– bridge. Weak interaction analysis revealed that complexes Co1 and Co2 exhibited 6-connected shp and 14-connected fcu nets, respectively. Magnetic studies showed that Co1 demonstrated single-ion magnet behavior under 2000 Oe. These behaviors are indicative of clearly field-induced single-ion magnetic behavior with Ueff = 34.7(2) K and τ0 = 2.7(2) × 10–7 s under 2000 Oe dc field, respectively. By contrast, Co2 lacked frequency dependence under zero-field conditions. Electrospray ionization mass spectrometry indicated that two complexes were stable in N,N-dimethylformamide.

We have synthesized a new spin-1/2 antiferromagnet, Y2Cu7(TeO3)6Cl6(OH)2, via a traditional hydrothermal method. This compound crystallizes in the triclinic crystal system with space group P1. The magnetic ions constitute a two-dimensional layered lattice with a novel topological structure in which the Cu4 clusters make up distorted diamond chains along the a axis and these chains are connected by the Cu3 trimers. The magnetic susceptibility and specific heat measurements show that the compound is antiferromagnetically ordered at TN = 4.1 K. This antiferromagnetic ordering is further supported by electron spin resonance (ESR) data. The magnetization curve presents a field-induced metamagnetic transition at 0.2 T, followed by a magnetization plateau within a wide magnetic field range from 7 T to at least 55 T, which corresponds to 3/7 of the saturated magnetization with g = 2.15 obtained from ESR. The possible mechanism for the magnetization plateau is discussed.

The Mn3+ doped single crystal samples CuFe1−xMnxO2 with x = 0.01, 0.03 and 0.05 were synthetic by floating zone method, and their magnetization and electric polarization were measured with static and pulsed high magnetic field up to 50 T in the temperature ranging from 2 to 300 K. A series of field-induced magnetic phase transitions and electric polarization, which show obviously anisotropy, were observed in all the doped samples, and their critical fields were directly related to the Mn3+ doping level. The pulsed high magnetic dielectric polarization measurements show that, in the ferroelectric incommensurate phase, the spontaneous electric polarization region is enhanced by the Mn3+ dopant. The impact of the Mn3+ substitution on magnetic and electric polarization behaviors may associate with the partial release of spin frustration in the CuFeO2. Based on the experimental results, the impact of Mn3+ doping on the magnetization and electric polarization behavior as well as their anisotropy are investigated and a detailed magnetic diagram are assumed.

It has been established that the formation of point defects and their behaviors could be regulated by growth details such as growth techniques and growth conditions. In this work, we prove that C doping approaches have great influence on the charge state of [Formula: see text], thus the interaction between H and C in GaN. For GaN with intrinsic C doping, which is realized by reducing the V/III ratio, [Formula: see text] mainly exists in the form of [Formula: see text] charged from the higher concentration of [Formula: see text] and, thus, may attract [Formula: see text] by coulomb interaction. Whereas for the extrinsically C doped GaN with propane as the doping source, the concentration of [Formula: see text] is reduced, and [Formula: see text] mainly exists in neutral charge state and, thus, nearly does not attract H ions. Therefore, we demonstrate that the interplay between H and C atoms is weaker for the extrinsically C doped GaN compared to the intrinsically doped GaN, thus gives a clear picture about the different charge states of [Formula: see text] and the formation of C–H complexes in GaN with different C doping approaches.

Systematic substituent variations on amidinate ligands bring delicate changes of CrN4 coordination in a family of chromium(II) complexes with the common formula of Cr(RNC(CH3)NR)2, where R = iPr (1), Cy (2), Dipp (Dipp = 2, 6-diisopropylphenyl) (3), and tBu (4). With the largest substituent group, 4 shows the largest distortion of the N4 coordination geometry from square-planar to seesaw shape, which leads to its field-induced single-molecule magnet (SMM) behavior. This is an indication that 4 has the strongest axial magnetic anisotropy and/or optimized magnetic relaxation process. Combined with high-frequency/field electron paramagnetic resonance (HF-EPR) experiments and ab initio calculations, we deduce that the smallest energy gap between ground 4Ψ0 and the first excited 4Ψ1 orbitals in 4 contributes the most to its strongest magnetic anisotropy. Moreover, the lower E value of 4 ensures its being a field-induced SMM. Specifically, the D and E values were found to be correlated to the dihedral angle between the ΔN1CrN2 and ΔN3CrN4 triangles, indicating that distortion from ideal square-planar geometry to the seesaw help increase axial magnetic anisotropy and suppress the transversal part. Thus, the study on this system not only expands the family of Cr(II)-based SMMs but also contributes to a deeper understanding of magneto-structural correlation in four-coordinate Cr(II) SMMs.

A tetranuclear cubane-type complex [Co4(ntfa)4(CH3O)4(CH3OH)4] (1) with a {Co4O4} core, and a mononuclear complex [Co(ntfa)2(CH3OH)2] (2) have been rationally obtained by adjusting the ratio of the β-diketonate and Co(II) ions, with the synthetic processes being monitored by in situ microcalorimetry. Then, following synthetic conditions to obtain 2, but using three distinct N-donor coligands - 2,2'-bipyridyl (bpy), 6,6'-dimethyl-2,2'-bipyridyl (6,6-(CH3)2-bpy) and 5,5'-dimethyl-2,2'-bipyridyl (5,5-(CH3)2-bpy) - three novel mononuclear complexes have been obtained, [Co(ntfa)2(bpy)2] (3), [Co(ntfa)2(6,6-(CH3)2- bpy)2] (4) and [Co(ntfa)2(5,5-(CH3)2-bpy)2] (5). The introduction of different capping coligands - as singlecrystal X-ray crystallography ascertains - fine-tunes the structures, with changes in both the distortion degree of the coordination geometry and the intermolecular interactions, which have a direct impact on the magnetic properties of these complexes. Magnetic investigations reveal field-induced single-ion magnet behavior in all complexes with distinct energy barriers (Ueff) −39.06 (1), 36.65 (2), 36.32 (3), 28.26 (4) and 15.85 K (5). Magnetic experiments together with HF-EPR measurements and theoretical calculations demonstrate that 2 features easy-axis magnetic anisotropy (D = −60.48 cm−1), whereas 3-5 show easy-plane magnetic anisotropies − D = +70.77 cm−1 for 3, +35.71 cm−1 for 4, and +51.28 cm−1 for 5. To our knowledge, such reversal of anisotropic nature driven by coligands is unprecedented.

Water reorientation is essential in a wide range of chemical and biological processes. However, the effects of such reorientation through rotation around the metal–oxygen bond on the chemical and physical properties of the resulting complex are usually ignored. Most studies focus on the donor property of water as a recognized σ donor-type ligand rather than a participant in the π interaction. Although a theoretical approach to study water-rotation effects on the functionality of a complex has recently been conducted, it has not been experimentally demonstrated. In this study, we determine that the magnetic anisotropy of a Co(II) complex can be effectively controlled by the slight rotation of coordinating water ligands, which is achieved by a two-step structural phase transition. When the water molecule is rotated by 21.2 ± 0.2° around the Co–O bond, the directional magnetic susceptibility of the single crystal changes by approximately 30% along the a-axis due to the rotation of the magnetic anisotropy axis through the modification of the π interaction between cobalt(II) and the water ligand. The theoretical calculations further support the hypothesis that the reorientation of water molecules is a key factor contributing to the magnetic anisotropy transition of this complex. Little is known about how the orientation of coordinated water molecules affects the magnetic properties of single molecule magnets. Here the authors combine experimental data and theoretical calculations to study how the rotation of water molecules alters the magnetic anisotropy of a pyrazine-based cobalt(II) complex.

A new free carbon radical was obtained in a microwave-assisted solvothermal reaction of the primary amine (1-methyl-1H-benzo[d]imidazol-2-yl)methanamine with FeCl3 ⋅6 H2 O in methanol at 140 °C. Through a combination of crystallography and electrospray ionization mass spectrometry, the reaction process was studied. The longest domino reaction includes 14 steps and forms up to 12 new covalent bonds (9 C-N and 3 C-C bonds) and 3 five-membered heterocycles. For the first time, the homolytic cleavage of a C-O bond was used to synthesize a triarylmethyl radical.

Two mononuclear cobalt(II) complexes, with the formulas [Co(2,6-dfba)2(bpp)2(H2O)2]n (1) and [Co(2,6-dfba)2(bpe)2(H2O)2]n (2) (2,6-Hdfba = 2,6-difluorobenzoic acid, bpp = 1,3-bis(4-pyridyl)propane, bpe = 1,2-bis(4-pyridyl)ethylene), have been synthesized by combining Co(II) ions with benzoate derivatives and two homogeneous N-donor ligands, respectively. Constrained by the analogous CoN2O4 coordination spheres, the discretely hexa-coordinated Co(II) cores in both complexes display stretched octahedral geometries. The equatorial environments in both complexes are identical, whereas the axial sites are finely modulated by the different chemical natures of the terminal N-donor ligands. The combined analyses of the magnetic data, the high-frequency electron paramagnetic resonance (HF-EPR) and the ab initio calculations unveil large easy-plane magnetic anisotropies for both complexes (D = +53.19 and +65.67 cm−1 for 1 and 2, respectively), which function as field-induced single-ion magnets (SIMs) with effective barriers (Ueff) of 45.34 (1) and 57.97 K (2). This work demonstrates how fine-tuning the coordination microenvironment of metal ions results in a non-negligible manipulation of their magnetic anisotropy.

Mixed (phthalocyaninato)(porphyrinato) rare earth double-decker complexes MIII(Pc)(TNP) (M = Tb (1), Dy (2), and Y (3); Pc = phthalocyaninate; TNP = tetranaphthylporphyrinate) were synthesized and characterized by elemental analysis and a range of spectroscopic methods. They represent the first examples of double-decker rare earth complexes containing a tetranaphthylporphyrin ligand. The neutral radical state of 1–3 was revealed by electronic absorption measurements, as indicated by the characteristics involving the semi-occupied molecular orbitals (SOMOs). The IR spectra show a marker band of a phthalocyanine radical anion (Pc˙−) at 1312–1314 cm−1, suggesting the high population of a π-radical electron on the Pc ring in the double-decker complexes 1–3. The magnetic behavior of both 1 and 2 features a slow relaxation of magnetization at low temperature under a zero direct current field, demonstrating the SMM nature of such lanthanide–radical systems. In particular for DyIII(Pc)(TNP) (2), the quantum tunneling of magnetization (QTM) was suppressed at an applied direct current (dc) field of 2000 Oe, leading to the extraction of an effective energy barrier of Ueff = 15.5 cm−1 (22.3 K) and τ0 = 7.74 × 10−7 s. The magnetic exchange couplings were analysed by means of high-frequency electron paramagnetic resonance (HF-EPR) measurements. The results clearly show the ferromagnetic exchange coupling between 4f- and delocalized π-radical spins in TbIII(Pc)(TNP) (1) and DyIII(Pc)(TNP) (2), with exchange coupling constants (JLn-rad) of 3.43(10) and 2.74(10) cm−1, respectively.

A one-dimensional (1D) coordination polymer, [{Co2(pymca)2·(H2O)4}SO4·2H2O]n (1) (pymca = 2-carboxypyrimidine), was solvothermally synthesized via the reaction of 2-cyanopyrimidine and Co(SCN)2. A bidentate pymca ligand was formed in situ by the hydrolysis of 2-cyanopyrimidine. Furthermore, in this study, the magnetic properties of complex 1 were investigated in detail. The results indicated that complex 1 showed a single-chain magnet (SCM) behavior below ca. 3 K. The energy barrier (Δτ1/kB) and preexponential factor (τ0) of SCM were 31.2 K and 5.4 × 10−9 s, respectively.

The 1,2-diaza-4-phospholide (dp−) dipotassium ate complexes of chromium(II) {[(η1-N-3,5-tBu2dp)4Cr][(η5-(N,N,C,C,P))2-K(η1-O-THF)2]2} (5) and {[(η1-N-3,5-Ph2dp)4Cr][(η5-(N,N,C,C,P))2-K(η1-O-THF)2]2}∞ (6) were synthesized and characterized by X-ray single crystal structure analysis. Complex 5 with a near-square planar geometry at the chromium(II) ion was unambiguously characterized by the high field electron paramagnetic resonance (HF-EPR) technique and magnetic measurements, revealing that it is a field-induced single-molecule magnet (SMM).

Strong Mn-Mn coupling interactions (dipole-dipole and spin-exchange), predominantly determined by statistically and apparently short Mn···Mn distances in traditional heavily Mn

Summary Low-coordinate zero-valent metal species are implicated as key intermediates in various transition-metal-catalyzed and -mediated reactions. However, knowledge on this type of metal species has been mainly restricted to the metals in groups 8–10, and that on the earlier transition-metal analogs is very limited. Herein, we report three-coordinate formal Mn(0) complexes [(NHC)Mn(η2:η2-dvtms)] (NHC = N-heterocyclic carbene, dvtms = divinyltetramethyldisiloxane). Spectroscopic and computational studies established that these formal Mn(0) complexes have an S = 3/2 ground-spin state and feature strong metal-to-alkene π backdonation. As a result of the high covalency of the metal-ligand bonding, these formal Mn(0) complexes are best described as resonance among a series of limiting canonical structures of Mn(0)-dvtms, Mn(II)-[dvtm]2–, and Mn(IV)-[dvtms]4–. These formal Mn(0) complexes can perform reductive coupling with unsaturated hydrocarbons and show diversified reactivity toward H2O, H2, CO, and I2, which hint at the synthetic utility of the three-coordinate formal Mn(0) species.

Two mononuclear Co(II) complexes [Co(L)4(NO3)2] (L = 3-phenylpyrazole for 1 and 4-methylpyridine for 2) featuring distorted octahedral geometry were prepared and structurally characterized by X-ray crystallographic analyses. Direct-current magnetic and high-frequency/field electron paramagnetic resonance measurements reveal that both complexes have the large and positive D values with the non-negligible transverse anisotropy (E). Slow magnetic relaxation effects were observed under the applied direct-current field in 1 and 2 by dynamic alternative-current magnetic susceptibility measurements, which provide two interesting examples of six-coordinate Co(II)-based single ion magnets constructed by nitrate groups and nitrogen heterocyclic compounds in mono-dentate coordination modes.

By utilizing the quinolinic derivative, 8-carboxymethoxy-2-carboxylicquinoline (L), five transition metal coordination complexes, [M(L)(H2O)3]·H2O] (M = Mn (1), Co (2)), [Ni(L)(H2O)2] (3), and {[M(L)](H2O)}n (M = Ni (4), Cu (5)), were synthesized by hydrothermal methods employing similar synthetic strategies. The crystal structures, magnetism and high-field EPR were characterized for the obtained compounds. 1–3 are mononuclear compounds. 1 and 2 have pentagonal bipyramidal geometry, while 4 and 5 exhibit one-dimensional zig-zag chain. Direct current magnetic and EPR studies demonstrate that compound 2 has large and positive D value (∼70.4 cm–1), indicating the easy plane magnetic anisotropies of 2. This D value is the largest one in the reported Co(II) complexes with pentagonal bipyramidal geometry. Field-induced slow magnetic relaxation behavior was observed for 2 by the dynamic ac magnetic susceptibility measurements. The dc magnetic susceptibility studies of 4 and 5 give similar weak MII–MII antiferrom...

By utilizing a flexible tetrapyridinate ligand, tetrakis(4-pyridyloxymethylene) methane(L), a novel multifunctional soft porous framework, [Co(NCS)2(L)]·2H2O·CH3OH (1), was constructed. This framework exhibits quick and selective solvatochromic and vapochromic behavior during a reversible crystal-to-amorphous-to-crystal (CAC) transformation. Importantly, the rapid CAC transition can selectively be triggered by methanol molecules, even at low concentrations of liquid or gaseous methanol. This reproducible transition can be monitored by single-crystal and power X-ray analysis, IR, and UV–vis, which all powerfully illustrate the selectivity and sensitivity of this system. In addition, the typical magnetic behavior of single ion magnets (SIMs) has been successfully introduced into this 3D framework, and the modified dynamic relaxations have been investigated via experimental and theoretical analysis. The consistent observations of both experimental and theoretical results support that the distortions of the m...

A new two-dimensional (2D) fluorophosphate compound Na3Cu5(PO4)4F·4H2O with a Cu5 cluster has been synthesized using a conventional hydrothermal method. The compound crystallizes in the orthorhombic crystal system with space group Pnma. The 2D layered structure is formed by cap-like {Cu5(PO4)4F} building units consisting of a Cu4O12F cluster plus a residual cap Cu2+ ion. Magnetic susceptibility exhibits a broad maximum at T2 = 19.2 K due to low-dimensional character followed by a long-range antiferromagnetic ordering at T1 = 11.5 K, which is further confirmed by the specific heat data. High-field magnetization measurement demonstrates a 2/5 quantum magnetization plateau above 40 T. The ESR data indicate the presence of magnetic anisotropy, in accordance with the 2D structure of the system.

CuFe0.99Mn0.01O2 and CuFe0.99Co0.01O2 single crystal samples are grown by a floating zone technique and their magnetization and spontaneous electric polarization have been investigated. Similarly with pure CuFeO2, an obviously anisotropic magnetization and spontaneous electric polarization were observed in the both doped samples, and their phase transition critical fields and temperatures are directly doping ion dependent. Considering the different d-shell configuration and ionic size between Mn3+, Co3+ and Fe3+ ions, in which the Mn3+ ion with Jahn-Teller (J-T) effect has different distortion on the geometry frustration from both of Fe3+ and Co3+ ion. Since for Mn3+ ion, the orbital splitting results from the low-symmetry J-T distortion in a crystal-field environment leads to a distorted MnO6 octahedron, which different from undistorted FeO6 and CoO6 octahedrons. The strain between distorted and undistorted octahedrons produces different effects on the spin reorientation transition and spontaneous electric polarization. Although the pure CuFeO2 has a very strong and robust frustration, the presence of the strain due to the random distribution of distorted MnO6 octahedron and undistorted CoO6 (FeO6) octahedrons leads to its spin reorientation transitions and spontaneous electric polarization different from CuFeO2.