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The first isolable Ge5-spiropentadiene 1 was synthesized via the reduction of (iPr3Si)2NGeCl (3) with potassium. The crystal structure of 1 reveals a spirocyclic Ge5 skeleton containing two Ge-Ge double bonds (avg. 2.34 A), which are fettered in two Ge3 rings with a dihedral angle of 70.193°. The DFT calculations and orbital analysis show that the σ-delocalization of the Ge5 skeleton and the 2π-delocalized aromatic Ge3 rings enhance the stability of molecule 1.

Host-Guest interaction is crucial to the sensitivity of heterogeneous sensors. Here, a series of isomorphic three-dimensional lanthanide metal-organic frameworks (Ln-MOFs), [Ln(TCBA)(H2O)2]2·DMF [H3TCBA = tris(3'-carboxybiphenyl)amine; Ln = Tb (1), Eu (2), and Gd (3); DMF = dimethylformamide] was synthesized and characterized, in which the propeller-like TCBA3- ligands adopt special torsional link between Tb(III) ions to form one-dimensional triangular channels. Optical experiments show that 1 exhibits bright green luminescence with an overall quantum yield of 26%, a 5D4 lifetime of 478 μs, and can act as an excellent heterogeneous fluorescent sensor to detect 2,4,6-trinitrophenol (TNP) explosive with an extremely low detection limit of 1.64 ppb. Because the confined channels within 1 exhibit matched dimensions toward TNP and feature multiple guest-response sites including rich π-conjugated groups, electron-donating N centers, and open metal nodes, strong host-guest interactions between 1 and TNP are captured and accurately determined by online microcalorimetry, which provides a distinctive thermodynamic perspective to understand the heterogeneous sensing behaviors. Additionally, the finely modulated heterometallic isomorphism [Tb0.816Eu0.184(TCBA)(H2O)2]2·DMF emits bright white light when excited at 380 nm and could potentially be used as single-phase white light-emitting diode phosphors materials.

It is an important issue to balance energy and sensitivity in the construction of high energy materials. Herein, two furozacycline energetic complexes ([Zn(HTZF)(H2O)3]·H2O (1) and [Co(HTZF)(H2O)3]·2H2O (2) (HTZF = 3-hydroxyl-4-(tetrazol-5-yl)furazan)) were hydrothermally synthesized. Single crystal X-ray diffraction shows that in 1, energetic ligand adopting bidentate chelating coordination mode coordinates to Zn2+. The coordinated units Zn(HTZF)2(H2O)2 and Zn(H2O)4 are alternatively linked to an infinite chain through nitrogen atom in furazan group, and with the aid of hydrogen bonding interaction, forming 3D supramolecule structure. Different in 2, ligand coordinates to Co2+ in bidentate chelating coordination and bridging coordination modes. π⋯π interaction further supports 3D framework stabilization. The thermal decomposition temperature of 1 and 2 are up to 293.0 °C and 295.8 °C, respectively. The heat of detonation (Q), detonation velocity (D), and detonation pressure (P), were evaluated to be, for 1: 1.123 kcal·g−1, 7.971 km·s−1 and 30.8 GPa; for 2: 2.165 kcal·g−1, 8.846 km·s−1 and 35.3 GPa. 1 and 2 are insensitive to impact and friction. As combustion promoter, both of complexes can effectively accelerate the thermal decomposition of ammonium perchlorate (AP).

A series of binuclear dysprosium compounds, namely, [Dy(api)]2 (1), [Dy(api)]2·2CH2Cl2 (2), [Dy(Clapi)]2·2C4H8O (3), and [Dy(Clapi)]2·2C3H6O (4) (H3api = 2-(2-hydroxyphenyl)-1,3-bis[4-(2-hydroxyphenyl)-3-azabut-3-enyl]-1,3-imidazoline; H3Clapi = 2-(2′-hydroxy-5′-chlorophenyl)-1,3-bis[3′-aza-4′-(2′′-hydroxy-5′′-chlorophenyl)prop-4′-en-1′-yl]-1,3-imidazolidine), have been isolated by the reactions of salen-type ligands H3api/H3Clapi with DyCl3·6H2O in different solvent systems. Structural analysis reveals that each salen-type ligand provides a heptadentate coordination pocket (N4O3) to encapsulate a DyIII ion and all of the DyIII centers in 1–4 adopt a distorted square antiprism geometry with D4d symmetry. Magnetic studies showed that compound 1 did not exhibit single-molecule magnetic (SMMs) behavior. With the introduction of different lattice solvents, compounds 2–4 showed filed-induced slow magnetic relaxation with barriers Ueff of 18.2 K (2), 28.0 K (3) and 16.4 K (4), respectively. Ab initio calculations were employed to interpret the magnetization behavior of 1–4. The combination of experimental and theoretical data reveal the importance of the weak exchange interaction between the DyIII ions in the observation of slow magnetic relaxation, and a relaxation mechanism has been developed to rationalize the observed difference in the Ueff values. The different lattice solvents influence Dy–O–Dy bond angles and thus alter the torsion of the square antiprism geometry, consequently resulting in distinct magnetic interactions and the magnetic behavior.

A family of new structurally manipulable pentagonal-bipyramidal (PBP) DyIII SMMs, with formulas [Dy(Hbpen)(Cl)3] (1), [Dy(Hbpen)Cl(OPhBr2NO2)2] (2), [Dy(Hbpen)(OPhCl2NO2)3] (3) and [Dy(Mbpen)(Cl)3] (1CH3), were controllably prepared based on a H-substituted amine-based ligand N,N′-bis(2-pyridylmethyl)-ethylenediamine (Hbpen) or a CH3-substituted amine-based ligand N,N′-dimethyl-N,N′-bis(2-pyridylmethyl)-ethylenediamine (Mbpen) and are compared with the reported imine-based DyIII analogues (1′–3′). Upon fine-modulating the type of nitrogen donor on the pentagon plane, the electronic effect is efficiently implemented to significantly modify the magnetic anisotropy and SMM behavior of PBP complexes. Notably, the amine-based 2 shows a three-fold improved energy barrier and an observable hysteresis opening up to 3 K. 1 and 1CH3 exhibit slower relaxation and enhanced anisotropy compared to the imine-based analogue, accompanied by the reorientation of magnetic easy axes. Conversely, poor magnetic properties are observed in 3 after the reduction of imine. The changes in SMM behavior and uniaxial anisotropies are rationalized by both experimental and theoretical studies. The H-substituted amine has formally a larger magnitude of negative charge than imine due to the polarized N–H σ bond. However the repulsion generated by the sp3 N of amine towards the DyIII ion is also affected by the orientation of lone pair electrons. The present work provides a feasible way to rationally optimize the SMM performance of DyIII complexes, highlighting the importance of the electronic properties of an equatorial donor in controlling the quantum tunneling and the magnetic relaxation of PBP DyIII-SMMs.

International audience; We report the first bromine-bridged dinuclear [Dy(CyPO)(μ-Br)(Br)]·2CH single-molecule magnet with an effective energy barrier of 684 K and magnetic hysteresis below 3 K. The asymmetric Dy centres present two unique stereoisomeric octahedral coordination environments depending on the cis/trans disposition of the CyPO ligands, leading to the orthogonality of the easy magnetic axes that annihilates the dipolar interactions.

A 3D mixed-valence Co(III)-Co(II) compound [Co9(bta)10(Hbta)2(H2O)10] n ·[22(H2O)] n ( 1 ) (H2bta= N , N -bis(1 H -tetrazole-5-yl)-amine) was hydrothermally synthesized by reaction of Co(NO3)2·6H2O with H2bta·H2O. Compound 1 consists of three kinds of distorted-octahedral [CoII(N4O2)] paramagnetic nodes which are separated by [CoIII(bta)2(Hbta)]2-/[CoIII(bta)3]3- diamagnetic linkers to generate a 3D porous metal-organic framework (MOF) with alternative …Co(III)…Co(II)… array and channels incorporating water molecules. Under an applied magnetic field of 4000 Oe, compound 1 exhibits slow relaxation of magnetization at low temperatures, giving Δ E / k B =30.00 K and t 0=2.0×10-8 s.

A new Mn (III) Schiff-base coordination compound, [Mn(L)(NCS)]2 (H2L = N,N′-bis(5-chlorosalicylidene)-1,2-diaminoethane), has been synthesized and characterized structurally and magnetically. The target compound is a phenoxo-bridged dimeric compound with the isothiocyanate coordinating in a usual bent mode. A magnetic susceptibility study reveals that the target compound exhibits antiferromagnetic intra-dimer coupling between Mn (III) ions. The low temperature heat capacity of the compound over the temperature range (2 to 300) K has been measured using the heat capacity option of a Quantum Design Physical Property Measurement System (PPMS). The thermodynamic functions in the experimental temperature range have been determined by curve fitting. The standard entropy and enthalpy of the as-prepared compound at T = 298.15 K have been calculated to be (924.52 ± 10.17) J · K−1 · mol−1 and (133.47 ± 1.47) kJ · mol−1, respectively.

Reaction of rare earth metal ions with 1H-benzimidazole-2-carboxylic acid (H2BIC) acid yielded two rare earth organic frameworks [Ln(HBIC)3] n (Ln = Gd 1, Y 2; H2BIC) under hydrothermal conditions. Both compounds were structurally characterized by single-crystal X-ray diffraction. Their thermal stabilities, luminescent, and magnetic properties were also investigated. Compounds 1 and 2 are isomorphic and present 2-D networks constructed by bridging-chelating HBIC− linkers and rare earth cation nodes, in which each asymmetric unit consists of one crystallographically unique Ln(III) ion and three HBIC− with two kinds of coordination modes. The two compounds exhibit high-thermal stability, stable to 320 °C. Antiferromagnetic interactions between Gd(III) centers for 1 were observed from magnetic susceptibility data. 2 exhibits a strong blue emission band in the solid state.

An unusual heterometallic microporous metal–organic framework Cu 3 Cr(TSTC) 2 (H 2 O) 4 · x G ( 1 ) (H 4 TSTC = trans- stilbene-3,3′,5,5′-tetracarboxylic acid; G = guest molecules) was solvothermally synthesized and characterized. The structural analysis reveals that compound 1 features a 3D distorted NbO-type network with high solvent-accessible volume of 68.5% assembled by two kinds of distinct cages. The adsorption measurements (77 K) results show that compound 1 has a BET surface area of 2485 m 2 /g, exhibits the great heat of hydrogen adsorption in the range of 7.0–8.4 kJ/mol and significantly higher H 2 hydrogen storage of 2.70 wt.% under 1 bar than those of IRMOF-1 (1.32 wt.%), MOF-177 (1.25 wt.%), UMCM-2 (1.40 wt.%), UMCM-150 (2.10 wt.%) and HKUST-1 (2.18 wt.%).

A flexible multidentate ligand, 1H-benzimidazole-2-carboxylic acid, was synthesized to construct a series of lanthanide coordination polymers [Ln(HBIC)3]n (Ln = Eu (1), Tb (2), Gd (3), Pr (4), Nd (5); H2BIC = 1H-benzimidazole-2-carboxylic acid) under hydrothermal conditions. All the compounds were fully characterized by elemental analysis, IR spectroscopy, single-crystal X-ray diffraction, thermal analysis and various spectroscopic techniques. Structural analyses reveal that they are isostructural and feature a 2D wave-like layer structure with distorted grids, in which the adjacent Ln3+ centers are bridged by the HBIC− ligands with two kinds of new coordination modes and the adjacent HBIC− ligands are tightly bound by two types of distinct intra-layer hydrogen bonds. The adjacent 2D layers are further interconnected by strong inter-layer hydrogen bond ring motifs R22(10) to generate a 3D supramolecular architecture. Optical studies indicate that the compounds 1, 2, 4 and 5 exhibit characteristic luminescence emission bands of the corresponding lanthanide ions in the visible or near-infrared regions at room temperature. In particular, compound 2 displays bright green luminescence in the solid state with a satisfactory 5D4 lifetime of 1.2 ms and a high overall quantum yield of 31%, due to an ideal energy gap between the lowest triplet state energy level of H2BIC ligand and the 5D4 state energy level of Tb3+. The energy transfer mechanisms in compounds 1 and 2 were also described and discussed.

A series of 3d–4f heterometallic coordination polymers, formulated as {[Cu3Ln2(pydc)6(H2O)12]·4H2O}n [Ln=Tb (1), Eu (2), Dy (3), Ho (4), Lu (5)], {[CuNd2(pydc)4(H2O)3]·H2O}n (6) and {[Cu3Pr2(pydc)6(H2O)13]·4H2O}n (7) (where H2pydc=pyridine-2,5-dicarboxylic acid), have been hydrothermally prepared by reactions of H2pydc ligand with lanthanide ions in the presence of Cu(II) ion. X-ray crystal structure analysis reveals that these compounds exhibit rich structural chemistry. 1–5 are isomorphous and present a two-dimensional network constructed from Ln2Cu2L2(H2O)2 SBU rings and CuL2(H2O) building blocks. In 6, two-dimensional ladder-like layers based on Nd(III) belts and CuL2O2 units are assembled by H2pydc ligands into a three-dimensional open framework. Polymer 7 displays a two-dimensional wave-like layer structure containing two distinct ring units, in which a new coordination mode of the pydc2− ligand is observed. The results indicate that the coordination flexibility of the pydc2− ligand and lanthanide contraction effect play cooperative roles in the formation of coordination polymers with different polymeric architectures. Compounds 1–2 exhibit intense green and red luminescence emission characteristics of Tb(III) and Eu(III), respectively. Furthermore, elemental analyses (EA), infrared spectra (IR) and thermogravimetric analyses (TGA) of these compounds were also studied.

A family of new lanthanide compounds [Ln(HBIC)3]n [Ln = Ce (1), Dy (2), Er (3); H2BIC = 1H-benzimidazole-2-carboxylic acid] was obtained under hydrothermal conditions and characterized by elemental analysis, IR, X-ray single crystal diffraction, thermal and luminescent analyses. X-ray single crystal diffraction shows that compounds 1–3 are isotypic and exhibit 2D networks constructed by bridging-chelating HBIC– linkers and lanthanide ion nodes, in which each central lanthanide atom is surrounded by five flexible HBIC– ligands with two kinds of new coordination modes, yielding a distorted two-capped triangle prism arrangement. Moreover, the thermal and photoluminescence properties of 1–3 were also investigated.

Quinoline-8-oxy-acetate acid (8-qoacH) reacts with M(II) (M=Pb and Cd) to give rise to two coordination complexes [Pb(8-qoac)2] (1) and [Cd(8-qoac)(bdc)0.5(H2O)2] (2) under hydrothermal conditions. They are characterized by single-crystal X-ray diffraction, IR, elemental, thermal analyses and luminescent analysis. The Pb metal centers connect the 8-qoac anions to form a 1D linear chain in 1. In 2, two symmetrical [Cd(8-qoac)(H2O)2] are bridged by a 1,4-bdc2− to generate a coordination unit [Cd(8-qoac)(bdc)0.5(H2O)2], and all the units are further connected to a 2D supramolecular layer-like structure via hydrogen bonds. TG analyses indicate that 1 exhibits higher thermostability than 2. Fluorescence spectrum of compound 2 in solid state shows strong fluorescence property.

Two new energetic compounds, [M(BTE)(H{sub 2}O){sub 5}]{sub n} (M=Sr(1), Ba(2)) [H{sub 2}BTE=1,2-bis(tetrazol-5-yl)ethane], have been hydrothermally synthesized and structurally characterized. Single-crystal X-ray diffraction analyses reveal that they are isomorphous and exhibit 2D (4,4) net framework, generated by 4-connected Sr{sub 2}(H{sub 2}O){sub 10}/Ba{sub 2}(H{sub 2}O){sub 10} SBUs linked up by two independent binding modes of H{sub 2}BTE, and the resulting 2D structure is interconnected by hydrogen-bond and strong face to face {pi}-{pi} stacking interactions between two tetrazole rings to lead to a 3D supramolecular architecture. DSC measurements show that they have significant catalytic effects on thermal decomposition of ammonium perchlorate. Moreover, the photoluminescence properties, thermogravimetric analyses, and flame colors of the as-prepared compounds are also investigated in this paper. - Graphical abstract: Two novel 2D isomorphous alkaline earth metal complexes were assembled by 4-connected Sr{sub 2}(H{sub 2}O){sub 10}/Ba{sub 2}(H{sub 2}O){sub 10} SBUs and two independent binding modes of H{sub 2}BTE ligands, and the catalytic performances toward thermal decomposition of ammonium perchlorate and photoluminescent properties of them were investigated. Highlights: > Two novel alkaline earth energetic coordination polymers have been prepared.{yields} Both structures are layered based on 4-connected Sr{sub 2}(H{sub 2}O){sub 10}/Ba{sub 2}(H{sub 2}O){sub 10} SBUs and two distinct H{sub 2}BTE coordination modes.{yields}more » The dehydrated products of the compounds possess good thermostability and significant catalytic effects on thermal decomposition of AP.« less

Six lanthanide compounds [Ln(H2O)9](m-BDTH)3·9(H2O) where Ln = La (1), and [Ln(H2O)8](m-BDTH)3·9(H2O) (m-BDTH2 = 1,3-benzeneditetrazol-5-yl) where Ln = Lu (2), Yb (3), Er (4), Ho (5) and Y (6) were hydrothermally synthesized and characterized by elemental analyses, infrared spectra, powder X-ray diffraction (PXRD) and X-ray single crystal diffraction. PXRD indicates that 2–6 are isomorphous. Structural analyses reveal that 1 is coordinated by nine water molecules forming a capped-square antiprism, while 2–6 are coordinated by eight water molecules forming a simple square antiprismatic geometry. Effects of water molecules on thermal stability were also discussed by thermogravimetric (TG), DSC, and PXRD under different temperatures. TG analyses suggest that 1 loses lattice and coordinated water molecules with no diacritical boundary, and 6 removes lattice water molecules first and then coordinated water molecules. DSC and PXRD further confirm the consequence.

Based on the versatile ligand 3,5-bis(4-pyridyl)-1H-1,2,4-triazole (Hbpt) derived from an in situ metal/ligand reaction, a series of coordination compounds CoCl4(H3bpt)(H2O) (1), Cu(H2bpt)2(SO4)2(H2O)6 (2), [Ag(bpt)]n (3), [Co(Hbpt)(pa)]n (4), [Co(Hbpt)(pda)]n (5) and [Cu(Hbpt)(pda)(H2O)]n (6) have been constructed (pa = phthalate, pda = 1,3-phenylenediacetate). The structures of these targeted complexes have been characterized by X-ray single-crystal diffraction techniques. Structural analysis reveals that Hbpt adopts versatile coordination modes to arrange the metal ions in 0-D point, simple (4,4) layers and dinuclear core chains in 1–3, which are further extended via the benzenedicarboxylate connectors to give rise to a variety of coordination networks such as (4,4), (412 · 63), (64 · 82) topologies in 4–6. The supramolecular organization through hydrogen bonds is analyzed for these complexes and thermal stability of these crystalline materials has been explored by TG-DTG.