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The two-electron (2e−) oxygen reduction reaction (ORR) is a green way to produce hydrogen peroxide (H2O2).

The electrocatalyst prepared by anchoring Sn and Sb on honeycomb carbon substrate with large specific surface area has excellent ORR performance and high stability. Zinc-air battery based on the catalyst can run stably for more than 1100 hours.

Due to the inherent thermodynamic stability and kinetic inertness of CO

It is a crucial challenge to address both magnetic anisotropy and stability for single-molecule magnets (SMMs) used in next-generation nanodevices. Highly axial lanthanide SMMs with neutral charge ...

It is important to achieve a moderate sustained release rate for drug delivery, so it is critical to regulate the host-guest interactions for the rational design of a carrier. In this work, a nano-sized biocompatible metal-organic framework (MOF), Mg(H

Based on a nitrogen-rich Y-shape energetic ligand, tris(5-aminotetrazole)triazine (H3TATT), a new green solvent-free energetic metal–organic framework (EMOF) [Co(HTATT)]n, has been synthesized under hydrothermal conditions. X-ray single crystal structure analysis shows that [Co(HTATT)]n has a 3D framework structure with building units [Co1-(μ4′-HTATT)-Co1]. The thermal decomposition behavior, the kinetic parameters of the exothermic process, the calculated detonation properties and sensitivities to impact and friction stimuli of [Co(HTATT)]n were investigated. Using differential scanning calorimetry, [Co(HTATT)]n was explored as a combustion promoter to accelerate the thermal decomposition of ammonium perchlorate (AP). Experimental results indicated that [Co(HTATT)]n possesses potential application prospects in the field of greener propellants. Magnetic measurements performed on [Co(HTATT)]n with the tetrazolyl-bridged Co(II) EMOF structure display spin-glass behavior with the coexistence of spin-canting ordering below 4.0 K.

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 new ABW-type luminescent metal–organic framework (MOF) namely (H3O)[Zn2L(H2O)]·3NMP·6H2O (1), constructed with eco-friendly Zn2+ and the multicarboxylate intraligand (LH5) was designed, synthesized and fully characterized by X-ray single-crystal diffraction, steady-state absorption and emission spectroscopy, and SEM observations. The MOF-based suspension sensor 1 (NMP) demonstrated high sensitivity to low-concentration pesticides of chlorothalonil (CTL), nitrofen (NF), trifluralin (TFL), and 2,6-dichloro-4-nitroaniline (DCN), which was assigned to the synergistic effect of the photoinduced electron transfer and the fluorescence resonance energy transfer. With the highest luminescent detection efficiency (KSV up to 11.194 μmol−1 and LOD down to 2.93 ppm) to DCN, 1 (NMP) was successfully applied for the selective sensing of DCN. The MOF-based film sensor 1 (film) illustrated the selective visualization sensing of trace amounts of DCN. In addition, based on the high saturated vapor pressure of TFL and the unique bathochromic shift effect to the emission maxima of 1, the MOF-based luminescent vapor sensing device 1 (LED) successfully exhibited operability for sensing of TFL vapor. The results illustrated a feasible approach to construct new MOF-based luminescent sensors for selective sensing and visualization of pesticides.

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.

International audience; We report here a dinuclear DyIII iodine-bridged single-molecule magnet self-assembled by cis/trans coordination chemistry that displays a large anisotropy barrier of ca. 1300 K and a hysteresis opening temperature of 16 K. High temperature quantum tunnelling of magnetization is observed up to 56 K in zero-field and explained by the combination of the large anisotropy barrier and the local transverse field at the trans site. The results provide a model for thorough understanding of the effect of electronic structure on the magnetic behavior of lanthanide complexes.

In this work, a new energetic coordination polymer (ECP), [Cu(HBTI)(H2O)]n (1) (H3BTI = 4,5-bistetrazole-imidazole), was synthesized by a hydrothermal method. Due to the existence of coordination water molecules in 1, however, its energy density was limited, which led to the insufficient detonation performance. To further improve its detonation performance, [Cu(H2BTI)(NO3)]n (2) was then obtained by substituting the coordinated water molecule in 1 with nitrate through the coordination substitution reaction under acidic conditions. The structures of two ECPs were respectively characterized using X-ray single-crystal diffraction, and the theoretical density of 2 (2.227 g·cm-3) was greater than 1 (1.851 g·cm-3). Thermogravimetric analyses showed that 2 has a one-step rapid weight loss process compared with the two-step slow weight loss process of 1. The theoretical calculations indicated that the detonation performances of 2 were better than those of 1. Moreover, the promotion effects of two ECPs on the combustion decomposition of ammonium perchlorate were studied using a differential scanning calorimetry method.

We report here a dinuclear DyIII iodine-bridged single-molecule magnet self-assembled by cis/trans coordination chemistry that displays a large anisotropy barrier of ca. 1300 K and a hysteresis opening temperature of 16 K. High temperature quantum tunnelling of magnetization is observed up to 56 K in zero-field and explained by the combination of the large anisotropy barrier and the local transverse field at the trans site. The results provide a model for thorough understanding of the effect of electronic structure on the magnetic behavior of lanthanide complexes.

It is a crucial challenge to address both magnetic anisotropy and stability for single-molecule magnets (SMMs) used in next-generation nanodevices. Highly axial lanthanide SMMs with neutral charge and moderate coordination numbers represent promising magnetic materials. Here, using iodide ions with large volume and low surface charge density as weak donors, we report a six-coordinate neutral dysprosium SMM [Dy(Cy

AIEgens have been widely applied in the fields involving solid and aggregation states. However, the preparation of AIEgens with high brightness to obtain the optimum AIE performance remains a challenge. In this article, a finely structural design strategy for the creation of ultrabright AIEgens has been reported based on Ir(III) complexes. By stepwise heightening the motion activity of substituents, the AIE property of Ir(III) complexes can be activated with dramatically improved photoluminescence quantum yields in solid state. The dipole moment vector of substituents and the triplet lifetime of Ir(III) complexes were applied to verify the motion activity of substituents theoretically and experimentally. In addition, by the combination of AIE-active Ir(III) complex IrppyDPBA and air permeable, optically transparent ethylcellulose, a hypersensitive luminescent oxygen sensing film with ultrafast quenching/recovery cycles in 6.1 s was developed. And the high-brightness AIE significantly improved the oxygen sensitivity of Ir(III) complexes. Furthermore, the expeditious and high-definition development of latent fingerprints on the substrates of tinfoil, plastic, steel, and glass was demonstrated by the high-brightness AIE of IrppyDPBA in 3 min. The fingerprint photographs developed by IrppyDPBA were intact and legible enough to allow display and analyze down to level 3 details. Noteworthily, the synergistic enhancement of the AIE property and the RTP nature of Ir(III) complexes on LFP development was for the first time demonstrated.

Optimizing the microenvironment of MOF pore is an effective strategy to improve the sensitivity of MOF-based electrochemical biosensors. In this work, a series of isomorphic 3D chiral Ni-MOFs with different pore sizes were prepared and used to construct acetylcholinesterase (AChE) biosensors for the electrochemical detection of chiral drug inhibitor galantamine hydrobromide (GH). The combination of the dense metal nodes with intrinsic oxidase-like activity and the high active AChE, creates synergistic catalysis hydrolysis of acetylthiocholine chloride (ATCl) to produce fast sensing response. The more matched size and chirality of MOF pore significantly enhance the host–guest interactions between the substrate and biosensor, which allows the optimum AChE/L-Ni-BPY/DpAu/GCE platform to exhibit highly sensitive detection of GH, with a lowest detection limit of 0.31 pM and a wide linear range of 1 × 10−12 ~ 1 × 10−6 M among the reported pharmaceutical AChE inhibitor sensing systems. Such matching effect is identified and quantified with accurate apparent energy through the detailed microcalorimetry investigations, which well illustrates the structure–activity relationship of the as-synthesized biosensors. The thermodynamically-guided assembling strategy provides new insights into the development of practical MOF-based electrochemical sensors.

The rational design of component and coordination configuration of active center is critical and useful to the development of multifunctional MOF-based catalysts. Herein, a bifunctional Zn-MOF, Zn-ADBA, constructed by photoactive 4,4’-(9,10-anthracenediyl)dibenzoic acid (H2ADBA) ligand and Zn(II) ions, is employed as heterogeneous catalyst for efficient cyanosilylation and photocatalytic oxidative carbon–carbon coupling reactions. The unsaturated Zn(II) centers with strong Lewis acid character can effectively active aldehyde substates, which promotes Zn-ADBA to catalyze cyanosilylation of electron-withdrawing substituted benzaldehyde with a turnover frequency value up to 53.1 h−1. Meanwhile, the photo-functional ADBA2- ligands featuring large steric hindrance drive the Zn(II) center adopt the liver alcohol dehydrogenase (LADH) like characteristics, which renders Zn-ADBA (λmax absorption ​= ​406 ​nm) high-efficient photocatalytic oxidation of N-aryl-tetrahydroisoquinoline substrates with yields above 95% over 4 ​h under visible light. The recyclability of Zn-ADBA and the possible catalytic mechanisms are also systematically investigated by a series of experiments including PXRD, IR, EPR and DFT analyses.

We report the first bromine-bridged dinuclear [Dy(Cy

A series of binuclear dysprosium compounds, namely, [Dy(api)]

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.

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)(H

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.

AIE-active luminogens are attractive for bioimaging, sensors, and optical detections. However, controllably switching and adjusting the AIE activity of luminogens in aqueous media to perform the best of AIE performance under appropriate water fraction remains a challenge. Herein, we report the first case of switchable and adjustable AIE activity based on Pt(II) complexes. The AIE activity of Pt(II) complexes in aqueous media can be flexibly switched and adjusted via finely tuning the rotation activity of the substituents. And the rotation activity of the substituents have been experimentally confirmed by the luminescent lifetimes and theoretically verified by the dipole moments of Pt(II) complexes. Furthermore, luminescent oxygen sensing films were constructed by combining the AIE-active Pt(II) complexes with commercially available, low-cost ethyl cellulose (EC). With the attenuation of EC film thickness, swift-responding quenching/recovering cycles (7.7 s) of the PtTPA-EC(N10) oxygen sensing film were demonstrated. And the controllable AIE property of Pt(II) complexes can effectively improve the oxygen sensitivity and the homogeneity of oxygen sensing films.

The reasonable selection of functional ligands and active metal centers is a priority to fabricate multifunctional metal-organic framework (MOF) materials. Herein, a 3D bifunctional TbIII-MOF, [Tb(TCBPA)∙DMF]n (1) (H3TCBPA ​= ​tris(4′-carboxybiphenyl)amine), is constructed by photoelectricity active triarylamine chromophore and Tb(III) to show excellent photochemical sensing and supercapacitor performances. In 1, the TCBPA3− linkers bridge Tb(III) nodes in a highly torsional fashion to form a non-interpenetrating structure containing 1D rhombic channels with an effective window size of 10.6 ​× ​11.4 ​A2. The strong green emission and multiple nitrogen/oxygen active sites make 1 work as a reusable heterogeneous fluorescent sensor for ultrasensitive detection of Fe3+ ion with a low detection limit of 3.56 ​ppb. Electrochemical experiments show that the TbIII-MOF exhibits a high specific capacitance of 346 ​F ​g−1 ​at 1 ​A ​g−1 and a remarkable capacitance retention of 93% after 2000 cycles, suggesting outstanding long-term cycling stability and reversibility. Additionally, the possible Fe3+ sensing mechanism was also investigated systematically.

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.

The production and availability of enantiomerically pure compounds that spurred the development of chiral technologies and materials are very important to the fine chemicals and pharmaceutical industries. By coordinative alignment of enantiopure guests in the metal‒organic frameworks, we reported an approach to control over the chirality of homochiral crystallization and asymmetric transformation. Synthesized by achiral triphenylamine derivatives, the chirality of silver frameworks was determined by the encapsulated enantiopure azomethine ylides, from which clear interaction patterns were observed to explore the chiral induction principles. With the changing of addition sequence of substrates, the enantioselectivity of asymmetric cycloaddition was controlled to verify the determinant on the chirality of the bulky MOF materials. The economical chirality amplification that merges a series of complicated self-inductions, bulk homochiral crystallization and enantioselective catalysis opens new avenues for enantiopure chemical synthesis and provides a promising path for the directional design and development of homochiral materials.

Modifying electron transfer pathways is essential to controlling the regioselectivity of heterogeneous photochemical transformations relevant to saturated carbonyls, due to fixed catalytic sites. Here we show that the interpenetration of metal–organic frameworks that contain both photoredox and asymmetric catalytic units can adjust the separations and electron transfer process between them. The enforced close proximity between two active sites via framework interpenetration accelerates the electron transfer between the oxidized photosensitizer and enamine intermediate, enabling the generation of 5πe− β-enaminyl radicals before the intermediates couple with other active species, achieving β-functionalized carbonyl products. The enriched benzoate and iminium groups in the catalysts provide a suitable Lewis-acid/base environment to stabilize the active radicals, allowing the protocol described to advance the β-functionalization of saturated cyclic ketones with aryl ketones to deliver γ-hydroxyketone motifs. The homochiral environment of the pores within the recyclable frameworks provides additional spatial constraints to enhance the regioselectivity and enantioselectivity., Metal organic frameworks are promising catalysts due to their porous structure and the possible incorporation of multiple active sites. Here, the authors show that interpenetrated metal-organic frameworks containing both a photocatalyst and an organocatalyst catalyse the β-alkylation of carbonyl compounds.

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.

Based on an efficient in situ metal/ligand reaction, a serial of 3,5-disubstituted-1,2,4-triazoles were synthesized via cycloaddition of organonitriles and ammonia under microwave conditions. This synthetic protocol provides a concise and high-yield access to 3,5-disubstituted-1,2,4-triazoles in organic synthesis. Moreover, the tautomerism of the product was also investigated. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resources: Full experimental and spectral details.]

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.

A lanthanide coordination compound, [Sm3(5-nip)4(5-Hnip)(H2O)7·9H2O]n (5-H2nip = 5-nitroisophthalic acid), has been synthesized and characterized by elemental analysis, IR, TG-DSC, and single-crystal X-ray diffraction. Structural analysis reveals that the compound features two kinds of 1D channels with guest water molecules. TG-DSC curves show that the dehydrated product of the compound exhibits high stability up to 673 K. The enthalpy change of reaction of formation in water, Δ r H m θ (l), was determined to be (27.608 ± 0.133) kJ · mol−1 at (298.15 ± 0.01) K by microcalorimetry. Based on a designed thermochemical cycle and other auxiliary thermodynamic data, the enthalpy change of reaction of formation in solid at (298.15 ± 0.01) K and the standard molar enthalpy for the compound, Δ r H m θ (s) and Δ f H m θ , were calculated to be (96.8 ± 0.8) kJ · mol−1 and (−831.4 ± 16.0) kJ · mol−1, respectively. In addition, thermodynamics and thermokinetics of the reaction of formation of the compound were investigated in water.

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