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Multi-functionalised nano-platforms based on persistent-luminescence nanoparticles (PLNPs) have attracted considerable attention for biomedical applications owing to their lack of background noise and suitability for in vivo imaging without the need for in situ excitation. However, nano-platforms based on PLNPs for continuous photodynamic therapy (PDT) are currently lacking. Herein, we report a nano-platform (LiGa4.99O8:Cr0.01/IrO2, LGO:Cr/IrO2) prepared using PLNPs (LiGa4.99O8:Cr0.01, LGO:Cr) covalently bonded with iridium oxide nanoparticles (IrO2 NPs), producing near-infrared (NIR) persistent luminescence, "afterglow" PDT and photo-thermal therapy (PTT) effects. The LGO:Cr/IrO2 not only exhibits NIR-persistent luminescence at 719 nm and a PTT effect under 808 nm irradiation but also a continuous "afterglow" PDT effect without the need for in situ excitation owing to persistent energy transfer from LGO:Cr to the IrO2 NPs, in turn generating reactive oxygen species (ROS). This multi-functional nano-platform is expected to further promote the application of PLNPs in tumour treatment. [ABSTRACT FROM AUTHOR]

A new family of low-coordinate mononuclear DyIII single-molecule magnets [(TrapenTMS)Dy(LB)] (Trapen = tris(2-aminobenzyl)amine; TMS = SiMe3; LB = THF 1, pyridine 2, ONMe33) has been synthesized and structurally characterized by single crystal X-ray diffraction. The five-coordinate DyIII ions exhibit distorted triangular bipyramidal geometries, among the different neutral ligands LB on the apex and the same TrapenTMS ligand, making the pyramid base of the trigonal bipyramid. Magnetic data analysis reveals that 1–3 are characteristic of SMM behaviors without a dc field, accompanying an unambiguous quantum tunneling of magnetization. Under an extra dc field of 500 Oe, field-induced slow magnetic relaxation behaviors occur with Raman and/or QTM processes. Ab initio calculations were also performed to rationalize the observed discrepancy in the magnetic behaviors, and the result illustrates that the SMM behavior could be effectively manipulated by the axial symmetry of the triangular bipyramidal DyIII motifs. [ABSTRACT FROM AUTHOR]

Four air-stable mononuclear Co(II) complexes, with the formulas [Co(dapbh)(H2O)(CH3OH)] (1), [Co(Hdapbh)(N3)(CH3OH)]·(CH3OH) (2), [Co(H2aapbh)(CH3OH)2]·(NO3)2 (3) and [Co(H2bapbh)(H2O)(NO3)]·(NO3) (4), have been synthesized and structurally characterized by single crystal X-ray diffraction. In all of the complexes, the Co(II) centers constrained by the rigid pentadentate ligand H2LR with two protonable hydrogens adopt a heptacoordinated pentagonal-bipyramidal geometry. The combined analyses of magnetic data and ab initio calculations unveil large easy-plane magnetic anisotropies for these complexes (D = +37.338, +37.273, +41.138 and +41.139 cm−1 for 1–4, respectively), which indicate that the chemical alterations of the equatorial ligand and the ligand field strength in the axial positions synergistically fine-tune the magnitude of the D values. Magnetic investigations demonstrate the field-induced single-ion magnetic behavior in complexes 1, 2 and 4 with diverse energy barriers (Ueff) of 12.25 for 1, 44.15 for 2 and 48.72 K for 4, corresponding to the geometrical distortion of the heptacoordinated Co(II) ion. That is, the greatest deviation from the ideal D5h symmetry in 4 is responsible for the highest barrier. [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 air-stable Co(III)–Co(II) mixed-valence complexes of molecular formulas [CoIICoIII(L)(DMAP)3(CH3COO)]·H2O·CH3OH (1) and [CoIICoIII(L)(4-Pyrrol)3 (CH3COO)]·0.5CH2Cl2 (2) (H4L = 1,3-bis-(5-methyl pyrazole-3-carboxamide) propane; DMAP = 4-dimethylaminopyridine; and 4-Pyrrol = 4-pyrrolidinopyridine) were synthesized and characterized by single-crystal X-ray crystallography, high-field electron paramagnetic resonance (HFEPR) spectroscopy, and magnetic measurements. Both complexes possess one five-coordinated paramagnetic Co(II) ion and one six-coordinated Co(III) ion with octahedral geometry. Direct-current magnetic susceptibility and magnetization measurements show the easy-axis magnetic anisotropy that is also confirmed by low-temperature HFEPR measurements and theoretical calculations. Frequency- and temperature-dependent alternating-current magnetic susceptibility measurements reveal their field-assisted slow magnetic relaxation, which is a characteristic behavior of single-molecule magnets (SMMs), caused by the individual Co(II) ion. The effective energy barrier of complex 1 (49.2 cm−1) is significantly higher than those of the other dinuclear Co(III)–Co(II) SMMs. This work hence presents the first instance of the dinuclear Co(III)–Co(II) single-molecule magnets with a five-coordinated environment around the Co(II) ion. [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]

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]

The synthesis, characterization, crystal structure and detailed magnetic properties of a pyrazine (pyz) and azido (N3) bridged cobalt(II) compound of formula [Co(N3)2(pyz)] (1) are reported. Compound 1 shows a layered structure formed by Co(II) chains with double μ-N3(κN1,N1) bridges that are further connected by μ-(pyrazine-κN1,N4) bridges. The layers present weak van der Waals interactions between azido terminal groups. The magnetic properties show the presence of a metamagnetic behaviour in 1 with two critical fields of 200 and 400 mT at low temperatures. AC magnetic measurements show the presence of a long-range 2D ferromagnetic order at Tc ≈ 8.0–7.0 K for dc fields above 200 mT and a long-range 3D ferromagnetic order at Tc ≈ 4.5 K for dc fields above 400 mT. [ABSTRACT FROM AUTHOR]

Two novel dual-photosensitized stable complexes, namely [Eu(dpq)(BTFA)3] (1) and [Tb(dpq)(BTFA)3] (2), have been successfully assembled via a mixed ligand approach using dipyrido[3,2-d:2′,3′-f]quinoxaline (dpq) and 3-benzoyl-1,1,1-trifluoroacetone (BTFA). The crystallographic data reveal mononuclear lanthanide cores in both 1 and 2, in which each eight-coordinated Ln(III) ion is located in a slightly distorted dodecahedron (D2d). The room-temperature photoluminescence spectra of complexes 1 and 2 indicate that both BTFA and dpq can effectively sensitize Eu(III) and Tb(III) characteristic luminescence. Moreover, heterometallic Ln-complexes can be synthesized, leading to a new series of differently doped EuxTb1−x complexes. Luminescence experiments on them reveal dual-emission peaks of Eu3+ and Tb3+, which lead to a gradual change in the luminous colour between yellow-green, yellow, orange, orange-red and red upon increasing the Eu3+ content. On the basis of the intrinsic strong emission properties and nontoxic nature of complexes 1 and 2, we explore their potential application as cellular imaging agents. Fluorescence microscopy data suggest the cytosolic and nuclear localization of 1 and 2 in HeLa and MCF-7 cells. [ABSTRACT FROM AUTHOR]

pH-Dependent self-assembly and structural transformation have been observed in a series of porous In(III)-MOFs, H3O[In3(pta)4(OH)2]·10H2O (NXU-1), [In(pta)2]·C3H10N (NXU-2) and [In(pta)2]·C3H10N (NXU-3) (H2pta = 2-(4-pyridyl)-terephthalic acid). The structural diversities of NXU-1–3 reveal that the pH value of the reaction plays a key role in the assembly of In-MOFs. NXU-1 with excellent stability exhibits highly selective CO2 adsorption over CH4 as compared to NXU-2 and NXU-3, owing to the presence of abundant multiple active sites unveiled by theoretical calculations. [ABSTRACT FROM AUTHOR]

Anionic metal–organic frameworks (MOFs) are beginning to have a great impact in the field of absorption and separation of ionic organic molecules due to the enhanced electrostatic interactions between their anionic frameworks and counter-ionic guests. Herein, the rational design and synthesis of two mesoporous anionic MOFs, [Zn3(ITTC)3](Me2 NH2)3·3DMF·H2O (1) and [Cd2(ITTC)3](Me2NH2)5·2DMF (2), where H3ITTC = 4,4′,4′′-(1H-imidazole-2,4,5-triyl) tribenzoic acid, is reported. Structural analysis revealed that both materials are anionic MOFs with a 2-fold interpenetrating three dimensional (3D) framework. The cross sectional area of the open one-dimensional rectangular channels is 31.7 Å × 15.6 Å for 1, of which the architecture is indicative of an unprecedented (3,3,4,5)-connection topology. For 2, the diameter of the open one-dimensional regular hexagonal channel is about 34.1 Å, decorated with uncoordinated carboxyl O atoms, and the framework exhibits a (3,4)-connected fcu network. Due to their anionic frameworks and bulky pore window sizes, both MOFs can be employed for absorbing and separating the cationic organic dye methylene blue (MB). The results reveal that both MOFs have better dye adsorption selectivity for MB, than for MO and SDI, because of charge and size-matching effects, enabling them to be potential candidates for use in environmental cleaning. By comparison, 2 presents superior selectivity and adsorptivity for cationic MB which depends on the presence of a basic functionalized pore surface. [ABSTRACT FROM AUTHOR]

A series of five mononuclear β-diketonate-Dy(III) complexes, with formulas Dy(ntfa)3(Br-bpy) (1), Dy(ntfa)3(Br2-bpy) (2), Dy(ntfa)3(5,5-(CH3)2-bpy) (3), Dy(ntfa)3(4,4-((CH3)3)2-bpy) (4) and Dy(ntfa)3(4,4-(CH3)2-bpy) (5) (ntfa = 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione, Br-bpy = 5-bromo-2,2′-bipyridine, Br2-bpy = 4,4′-dibromo-2,2′-bipyridine, 5,5-(CH3)2-bpy = 5,5′-di-methyl-2,2′-bipyridine, 4,4-((CH3)3)2-bpy = 4,4′-di-tert-butyl-2,2′-bipyridine, and 4,4-(CH3)2-bpy = 4,4′-di-methyl-2,2′-bipyridine), have been prepared by altering the capping N-donor coligands. Dy(III) ions in all complexes possess N2O6 octa-coordinated environments, displaying a distorted square antiprismatic D4d symmetry in complexes 1–4, as well as a triangular dodecahedron D2d symmetry in 5. Magnetic investigations evidence the SIM behavior in the five complexes with the energy barriers (Ueff) of 104.19 K (1), 122.93 K (2), 84.20 K (3), 64.16 K (4) and 80.23 K (5) under zero applied dc field. The potential QTM effects in the title complexes are successfully suppressed in the presence of the extra applied fields. The crystal field parameters and orientations of the magnetic easy axes were obtained from the simulation of the magnetic data and the electrostatic model calculation. The distinct electronic effects originating from the subtle changes of the substituents on the capping N-donor coligands induce varying coordination microenvironments and geometries on the Dy(III) sites, further drastically impacting the overall magnetic properties of the title complexes. The disparities of the uniaxial anisotropy and the magnetic dynamics for 1–5 have been elucidated by ab initio calculations as well. [ABSTRACT FROM AUTHOR]

The reactions of LnIII ions with a versatile pyridyl-decorated dicarboxylic acid ligand lead to the formation of a series of novel three-dimensional (3D) Ln-MOFs, [Ln3(pta)4(Hpta)(H2O)]·xH2O (Ln = Dy (1), Eu (2), Gd (3), Tb (4), H2pta = 2-(4-pyridyl)-terephthalic acid, x = 6 for 1, 2.5 for 2, 1.5 for 3 and 2 for 4). The Ln3+ ions act as nine-coordinated muffin spheres, linking to each other to generate trinuclear {Ln3(OOC)6N2} SBUs, which are further extended to be interesting 3D topological architectures. To the best of our knowledge, the Dy-MOF exhibits zero-field single-molecule magnet (SMM) behaviour with the largest effective energy barrier among the previously reported 3D MOF-based Dy-SMMs. The combined analyses of a diluted sample (1@Y) and ab initio calculations demonstrate that the thermally assisted slow relaxation is mainly attributed to the single-ion magnetism. Furthermore, fluorescence measurements reveal that H2pta can sensitize EuIII and TbIII characteristic luminescence. [ABSTRACT FROM AUTHOR]

In the presence of different nitrogen-rich ligands, two energetic MOFs with formulas [Ag(tza)]n (1) and [Ag(atza)]n (2) (Htza = tetrazole-1-acetic acid and Hatza = (5-amino-1H-tetrazole-1-yl) acetic acid) were successfully synthesized and characterized. X-ray single crystal structure analysis shows that both 1 and 2 have 2D layer-like topologies. The experimental and theoretical evaluations reveal the promising properties of both energetic compounds, such as prominent heats of detonation, high thermal stabilities, good sensitivities and excellent detonation performances. In contrast to 1, interestingly, the introduction of the amino group in 2 leads to various coordination modes of the ligands and different stacking patterns of the frameworks, resulting in the observation of the shorter Ag–O, Ag–Ag, C–N, N–N, and N＝N bond lengths in 2. Consequently, 2 features superior heats of detonation and thermostability compared to 1. The nonisothermal thermokinetic parameters are obtained by using the Kissinger and Ozawa methods, while the standard molar enthalpies of formation are calculated from the determination of constant volume combustion energies. In addition, both compounds were explored as practical additives to promote the thermal decomposition of ammonium perchlorate (AP). This work may provide an effective approach for manipulating the energetic properties and thermostability of high-energy compounds via the perturbation of energetic groups. [ABSTRACT FROM AUTHOR]

Complexation of dysprosium(III) ions with a multidentate hydrazone ligand, N-[(E)-pyridin-2-ylmethylideneamino]pyridine-2-carboxamide (L), in the presence of different β-diketonate coligands, leads to the formation of two novel DyIII dimers, with formulas Dy2(BTFA)4(L)2 (1) and Dy2(TTA)4(L)2 (2) (BTFA = 3-benzoyl-1,1,1-trifluoroacetone and TTA = 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedionate). They exhibit slightly different coordination geometries around DyIII centers and discrepant binuclear motifs – as a result of altering the β-diketonate coligands – which has an impact on the magnetic interactions between metal centers, the local tensor of anisotropy on each DyIII site and their relative orientations, therefore contributing to distinct magnetization dynamics. Compared to 2, complex 1 exhibits a more significant slow magnetic relaxation of SMM behavior in the absence of a dc field. The QTM effect is effectively repressed under a static field, resulting in the energy barriers of 57 K for 1 and 38 K for 2. Ab initio calculations clarify that, strong single-ion magnetic anisotropies exist in both complexes, whereas intermetallic ferromagnetic interaction and antiferromagnetic interaction are observed in 1 and 2, respectively, therefore resulting in dissimilar magnetization dynamics. [ABSTRACT FROM AUTHOR]

The utilization of two isomorphic ligands with different substituents leads to two centrosymmetric DyIII dimers, namely, [Dy2(bfbpen)2(H2O)2]·2I− (1) and [Dy2(bcbpen)2(H2O)2]·2I−·0.5H2O (2) (H2bfbpen = N,N′-bis-(2-hydroxy-5-fluoro-benzyl)-N,N′-bis-(pyridin-2-ylmethyl)ethylenediamine and H2bcbpen = N,N′-bis-(2-hydroxy-5-chloro-benzyl)-N,N′-bis-(pyridin-2-ylmethyl)ethylenediamine). Although Dy ions in both compounds uniformly exhibit a square-antiprism geometry, the critical difference found in the terminal substituents of the two ligands fine-tunes the local crystal field around Dy centers and the dinuclear molecular structures of 1 and 2. Magnetic investigations unveil that both 1 and 2 display dynamic magnetic relaxation of single-molecule magnet (SMM) behaviour with different energy barriers of 20.9 K for 1 and 72.7 K for 2 under a zero direct-current (dc) field, as well as 26.9 K for 1 under a 1200 Oe dc field. Compared to 1, the stronger uniaxial anisotropy and magnetic exchange in 2 render it a better SMM as evidenced by the higher energy barrier. Ab initio calculations are also performed on both Dy2 compounds to rationalize the observed discrepancy in their magnetic behaviours. The contribution illustrates that the SMM behaviour could be effectively enhanced by means of deliberate local structural manipulation. [ABSTRACT FROM AUTHOR]

By means of the solvent effect, three new azido-copper 1D coordination polymers, [Cu(4-aba)(N3)] (1), [Cu(4-aba)(N3)(CH3OH)] (2), and [Cu(4-aba)(N3)(C2H5OH)] (3) (4-aba = 4-azidobenzoic acid), were successfully prepared in the presence of Cu2+ ion, NaN3 and 4-azidobenzoic acid. Interestingly, 1 can be employed as a precursor and transformed to 2 and 3via the coordination of methanol or ethanol, respectively. Meanwhile, the identical products of 1, namely 1a and 1b, could be obtained from both 2 and 3 by a dealcoholized process. As a result, the geometric configurations of Cu(ii) ions vary from the tetracoordinated square-planar in 1 to the hexacoordinated octahedron in 2 or 3. Compound 1 displays a well-isolated 1D chain with dual-bridges of EO-azido and syn,syn-carboxylate, while isomorphic 2 and 3 are triple-bridged chain-like motifs containing EO-azido, syn,syn-carboxylate and μ2-alkanol. The structural transformations caused by the intervention of alkanol molecules modulate the intrachain Cu–Cu distances (3.570 for 1, 3.204 Å for 2 and 3.154 Å for 3) and Cu–N–Cu angles (127.3° for 1, 106.82° for 2 and 104.81° for 3). This modulation, however, further leads to different intrachain ferromagnetic interactions (J = 28.4 cm−1 for 1, 67.6 cm−1 for 2, 40.2 cm−1 for 3) that are qualitatively demonstrated by theoretical calculation. More importantly, the significant scenarios of magnetic ordering and slow magnetic relaxation, which are infrequent in most of the reported azido-copper cases, are only observed in 2 and 3, due to the distinct interchain networks among 1–3. In addition, heat-capacity measurements highlight the characteristics of long-range ferromagnetic ordering in 2 and 3. [ABSTRACT FROM AUTHOR]

A novel one-dimensional azido-cobalt(ii) compound, [Co2(1-mbt)2(N3)4]n (1) (1-mbt = 1-((2-propyl-imidazol-1-yl)methyl)-benzo[1,2,3]triazole), was solvothermally synthesized. X-ray crystal structure analysis demonstrates that two crystallographically independent Co(ii) atoms in the asymmetrical unit of compound 1 exhibit a rectangular pyramid geometry. The 3D supermolecular network of 1 consists of well-isolated 1D metal chains in which the azido bridging ligands assume an unusual pattern of combination with the Co(ii) centre as the sign of [–EE–EO–EO–EO–]n. The various coordination modes of the azido anion are responsible for different magnetic exchanges between the adjacent Co(ii) ions. The end-to-end (EE) mode mediates the antiferromagnetic coupling, whereas the end-on (EO) manner contributes to the ferromagnetic interaction. Magneto-structural relationships are discussed with the aid of theoretical calculations which are employed to find the potential single-ion magnetic anisotropy and reproduce the observed magnetic coupling properly. Alternating current magnetic susceptibility measurements reveal that 1 features a typical behaviour of field-induced slow magnetic relaxation. Energetic characterization evidences that the resulting compound possesses satisfactory detonation properties, superior lack of sensitivity and thermostability owing to the high nitrogen content (N% = 40.10%) and a coherent intrachain configuration. The kinetic parameters of the exothermic processes for 1 are investigated by the Kissinger method and the Ozawa method. We note that 1 has potential application prospects as a new generation of environmentally friendly high-energy materials based on this nitrogen-rich and oxygen-free system. In addition, the compound is developed as a practical additive to promote the thermal decomposition of ammonium perchlorate (AP) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). The finding in this work highlights an example of effective development of advanced magneto-energetic materials. [ABSTRACT FROM AUTHOR]

Based on two fluoro-substituted phenylacetate isomers, o-fluorophenylacetic acid (o-Hfpa) and p-fluorophenylacetic acid (p-Hfpa), two new Cu(ii)-azido compounds, [Cu(o-fpa)(N3)(C2H5OH)]n (1) and [Cu(p-fpa)(N3)(C2H5OH)]n (2), have been prepared, and structurally and magnetically characterized. Single-crystal structure analyses indicate that compounds 1 and 2 consist of 1D chain-like coordination networks in which adjacent copper cations are linked by the alternating triple-bridges of μ-1,1-azido, syn,syn-carboxylate and μ2-ethanol. For the two title compounds, the diverse charge distributions on the carboxyl groups caused by distinct substituent effects of the two phenylacetate coligands lead to the different structural parameters of intrachain Cu–Cu distances (3.218 Å for 1 and 3.168 Å for 2) and Cu–N–Cu angles (106.82° for 1 and 104.81° for 2), further resulting in the disparity of magnetic behaviors. The dominant ferromagnetic couplings between neighbouring Cu(ii) ions in the two compounds (J = 87.08 cm−1 for 1, J = 66.05 cm−1 for 2) are due to the counter-complementarity of the multiple superexchange pathways, contributing to the interesting plots of a ferromagnetic order (Tc = 11.0 K for 1, 9.5 K for 2) and slow magnetic relaxation that are rarely observed in most of the reported azido-Cu(ii) architectures. Heat-capacity experiments further emphasize the characteristic long-range ferromagnetic ordering in compounds 1 and 2. Magneto-structural relationships of 1 and 2 are investigated as well. Moreover, DFT calculations (using different methods and basis sets) have been performed on both compounds to provide a qualitative and quantitative theoretical explanation of their magnetic behavior. [ABSTRACT FROM AUTHOR]

Employing two benzoate derivatives with different numbers of non-coordinated fluoro-substituents, 2-fluorobenzoic acid (2-Hfba) and 2,6-difluorobenzoic acid (2,6-Hdfba), two new azido-copper coordination polymers, [Cu(2-fba)(N3)(CH3OH)]n (1) and [Cu(2,6-dfba)(N3)(CH3OH)]n (2), have been successfully isolated, and then structurally and magnetically investigated. Single crystal structure analysis demonstrates that the metal cations in the two resulting compounds are connected by the alternating triple-bridge of μ-1,1-azido, syn,syn-carboxylate and μ2-methanol, contributing to analogously linear 1D Cu(ii) chain-like motifs with slightly different intrachain and interchain geometric parameters. The fine-tuned structures lead to variant magnetic properties in the two title compounds. Although a dominant ferromagnetic coupling between adjacent Cu(ii) ions within each chain due to the counter-complementarity of the multiple superexchange pathways is observed in both compounds, the interesting plots of magnetic ordering and slow magnetic relaxation, which are rare in most of the reported azido-Cu(ii) architectures, only occur in compound 1, while 2 behaves as an antiferromagnet consisting of ferromagnetic Cu(ii) chains. The heat-capacity experiments further emphasize the characteristic long-range ferromagnetic ordering in 1 and the typical behavior of antiferromagnets in 2. Moreover, density functional theory (DFT) calculations (using different methods and basis sets) have been performed on both compounds to obtain the qualitatively theoretical interpretation of the magnetic behaviors. [ABSTRACT FROM AUTHOR]

A reticular 3D heterometallic metal–organic framework (MOF), [Cu4Na(Mtta)5(CH3CN)]n (1) (N% = 40.08%), has been synthesized, using a 5-methyl tetrazole (Mtta) ligand formed from acetonitrile and azide, through in situ synthesis and structurally characterized by X-ray single crystal diffraction. The fluorescence spectra demonstrate that 1 undergoes an interesting structural transformation in aqueous solution, yielding the compound [Cu4Na(Mtta)5H2O]n (1a) as confirmed by 1H NMR, IR and PXRD. Thermoanalysis showed that 1 possesses excellent thermostability up to 335 °C. The calculated detonation properties and the sensitivity test illustrate that compound 1 could be used as a potential explosive. In addition, the non-isothermal kinetics for 1 were studied using the Kissinger and Ozawa–Doyle methods. The enthalpy of formation was obtained from the determination of the constant-volume combustion energy. [ABSTRACT FROM AUTHOR]

The synthesis, characterization, crystal structure and detailed magnetic properties of a pyrazine (pyz) and azido (N3) bridged cobalt(II) compound of formula [Co(N3)2(pyz)] (1) are reported. Compound 1 shows a layered structure formed by Co(II) chains with double μ-N3(κN1,N1) bridges that are further connected by μ-(pyrazine-κN1,N4) bridges. The layers present weak van der Waals interactions between azido terminal groups. The magnetic properties show the presence of a metamagnetic behaviour in 1 with two critical fields of 200 and 400 mT at low temperatures. AC magnetic measurements show the presence of a long-range 2D ferromagnetic order at Tc ≈ 8.0–7.0 K for dc fields above 200 mT and a long-range 3D ferromagnetic order at Tc ≈ 4.5 K for dc fields above 400 mT. [ABSTRACT FROM AUTHOR]