In Situ MOF-74-Pyrolysis-Generated Porous Carbon Supporting Spinel Cu0.15Co2.85O4/C Boosts Ammonium Perchlorate Accelerating Decomposition: Precise Cu Doping Modulating Oxygen Vacancy Concentration.

As one of the main components of solid propellant, ammonium perchlorate (AP) shows slow sluggish decomposition kinetics with unconcentrated heat release. To achieve efficient catalytical decomposition, it is a significant challenge to design reasonable catalyst structure and explore the interaction between catalyst and AP. Herein, a series of porous carbon supported spinel-typed homogeneous heterometallic composites CuxCo3-xO4/C via pyrolysis of MOF-74-Co doped Cu. On basis of precise electronic-structure-tuning through modulating Cu/Co ratio in MOF-74, Cu0.15Co2.85O4/C with 5% Cu-doping featuring oxygen vacancy concentration of 26.25% exhibits the decrease to 261.5 °C with heat release up to 1222.1 J g-1 (456.9 °C and 669.2 J g-1 for pure AP). The detail process of AP accelerated decomposition is approved by TG-DSC-FTIR-MS technique. Density functional theory calculation revealed that in the Cu0.15Co2.85O4/C, the distinctive ability for NH3 catalyzed oxidation assisted with absorption performance of active porous C boosts accelerating AP decomposition. The findings would provide an insight for perceiving and understanding AP catalytic decomposition.

Stable Hierarchical Porous Heterostructure Ni2P/NC@CoNi2S4 Fabricated via the NiCo-LDH Template Strategy for High-Performance Supercapacitors.

Transition metal phosphide/sulfide (TMP/TMS) heterostructures are attractive supercapacitor electrode materials due to their rapid redox reaction kinetics. However, the limited active sites and weak interfacial interactions result in undesirable electrochemical performance. Herein, based on constructing the NiCo-LDH template on Ni-MOF-derived Ni2P/NC, Ni2P/NC@CoNi2S4 with a porous heterostructure is fabricated by sulfurizing the intermediate and is used for supercapacitors. The exposed Ni sites in the phosphating-obtained Ni2P/NC coordinate with OH- to in situ form an intimate-connected Ni2P/NC@NiCo-LDH, and the CoNi2S4 nanosheets retaining the original cross-linked structure of NiCo-LDH integrate the porous carbon skeleton of Ni2P/NC to yield a hierarchical pore structure with rich electroactive sites. The conducting carbon backbone and the intense electronic interactions at the interface accelerate electron transfer, and the hierarchical pores offer sufficient ion diffusion paths to accelerate redox reactions. These confer Ni2P/NC@CoNi2S4 with a high specific capacitance of 2499 F·g-1 at 1 A·g-1. The NiCo-LDH template producing a tight interfacial connection, significantly enhances the stability of the heterostructure, leading to a 91.89% capacitance retention after 10,000 cycles. Moreover, the fabricated Ni2P/NC@CoNi2S4//NC asymmetric supercapacitor exhibits an excellent energy density of 73.68 Wh kg-1 at a power density of 700 W kg-1, superior to most reported composites of TMPs or TMSs.

Heterointerface Connection with Multiple Hydrogen-Bonding in Z-Scheme Heterojunction SiW9Co3@UiO-67-NH2 Deciding High Stability and Photocatalytic CO2 Reduction Performance.

Merging metal-organic frameworks (MOFs) and polyoxometalates (POMs) into heterogeneous heterojunction photocatalysts through in situ encapsulation is an effective approach to suppress the leachability of POMs and enhance their electron supply. The heterointerfacial connection in POMs@MOFs directly determines the performance of stability and charge separation, and the suited interaction between MOFs and POMs for POMs@MOFs heterojunctions photocatalyst is of vital importance. Here, a distinctive Keggin-type POM [(n-C4H9)N]10[SiW9Co3 (H2O)3O37]·17H2O (SiW9Co3) with near-total visible region absorption, narrow band gap of 2.23 eV, and powerful electron supply activity was prepared and tightly immobilized in the cavities of UiO-67-NH2 and UiO-68-NH2 to construct two Z-scheme heterojunctions SiW9Co3@UiO-67-NH2 and SiW9Co3@UiO-68-NH2, which were used for photocatalytic reduction of CO2 to CO. Their compositions, structures, and energy band features were fully characterized by a series of tests including XRD, FT-IR, SEM, XPS, UV-vis-DRS, UPS, and so forth. SiW9Co3@UiO-67-NH2 showed optimal photocatalytic performance with an excellent CO yield of 153.3 µmol-1·g-1·h-1 and a selectivity of 100%, which is 3.3-fold higher than that of SiW9Co3@UiO-68-NH2 and far superior to most reported POM-based heterojunctions. Comprehensive investigations with extensive photoelectric characterizations and microcalorimetric experiments demonstrated that the exceptional photocatalytic performances of SiW9Co3@UiO-67-NH2 could be attributed to the fact that (i) strong host-guest interactions were formed due to the well-matched dimensions between SiW9Co3 cluster and MOF cavity, which generated an intimate heterointerface to effectively accelerate interface electron transfer; (ii) the intimate heterointerface promoted SiW9Co3 to yield multielectron supply for efficient interfacial carrier neutralization owing to its donor-acceptor structure and narrow band gap. Additionally, the excellent durability of SiW9Co3@UiO-67-NH2 was also supported by the solidly locked SiW9Co3 and a stable MOF framework.

A Stable Triphenylamine-Based Zn(II)-MOF for Photocatalytic H2 Evolution and Photooxidative Carbon-Carbon Coupling Reaction.

Efficient charge transfer has always been a challenge in heterogeneous MOF-based photoredox catalysis due to the poor electrical conductivity of the MOF photocatalyst, the toilless electron-hole recombination, and the uncontrollable host-guest interactions. Herein, a propeller-like tris(3'-carboxybiphenyl)amine (H3TCBA) ligand was synthesized to fabricate a 3D Zn3O cluster-based Zn(II)-MOF photocatalyst, Zn3(TCBA)2(µ3-H2O)H2O (Zn-TCBA), which was applied to efficient photoreductive H2 evolution and photooxidative aerobic cross-dehydrogenation coupling reactions of N-aryl-tetrahydroisoquinolines and nitromethane. In Zn-TCBA, the ingenious introduction of the meta-position benzene carboxylates on the triphenylamine motif not only promotes Zn-TCBA to exhibit a broad visible-light absorption with a maximum absorption edge of 480 nm but also causes special phenyl plane twists with dihedral angles of 27.8-45.8° through the coordination to Zn nodes. The semiconductor-like Zn clusters and the twisted TCBA3- antenna with multidimensional π interaction sites facilitate photoinduced electron transfer to render Zn-TCBA a good photocatalytic H2 evolution efficiency of 27.104 mmol·g-1·h-1 in the presence of [Co(bpy)3]Cl2 under visible-light illumination, surpassing many non-noble-metal MOF systems. Moreover, the positive enough excited-state potential of 2.03 V and the semiconductor-like characteristics of Zn-TCBA endow Zn-TCBA with double oxygen activation ability for photocatalytic oxidation of N-aryl-tetrahydroisoquinoline substrates with a yield up to 98.7% over 6 h. The durability of Zn-TCBA and the possible catalytic mechanisms were also investigated by a series of experiments including PXRD, IR, EPR, and fluorescence analyses.

Influence of lattice water molecules on the magnetization dynamics of binuclear dysprosium(III) compounds: insights from magnetic and ab initio calculations.

Lattice water effects on the structures and magnetic properties of single-molecule magnets (SMMs) have attracted considerable attention. Herein, we have successfully synthesized two centrosymmetric binuclear compounds [Dy2(2,3'-ppcad)2(C2H3O2)4(H2O)2] (1) and [Dy2(2,3'-ppcad)2(C2H3O2)4(H2O)2]·6H2O (2) (2,3'-Hppcad = N3-(2-pyrazinyl)-3-pyridinecarboxamidrazone) by elaborately varying the amount of the base (LiOH·H2O). Through isothermal titration calorimetry (ITC), the interactions between DyIII ions and 2,3'-Hppcad with different amounts of LiOH·H2O were monitored in real time. Magnetic studies reveal that two compounds exhibit the typical zero-field single-molecule magnet behavior with different energy barrier (Ueff) values of 103.43 K for 1 and 386.48 K for 2, wherein the SMM performance for 2 stands out among the reported nine-coordinated Dy2-SMMs systems with spherical capped square antiprism (C4v) geometries. To rationalize the observed difference in the magnetic properties of 1 and 2, ab initio calculations have been performed. The introduction of lattice water molecules leads to differences in the J values observed for 1 and 2. The stronger antiferromagnetic DyIII-DyIII couplings in 2 were presented and the fast quantum tunneling of magnetization was further suppressed, thereby achieving a higher Ueff value. This work provides an effective strategy to enhance the SMM performance, and combines with ab initio calculations to explain how lattice water molecules can affect the magnetic interactions of Dy2-SMMs.

Copper nanocluster-Ru(dcbpy)32+ as a cathodic ECL-RET probe combined with 3D bipedal DNA walker amplification for bioanalysis.

In this study, a cathodic intra-molecular electrochemiluminescence resonance energy transfer (ECL-RET) probe was exquisitely designed via the integration of an ECL donor (Cu NCs) with an acceptor (Ru(dcbpy)32+), and further employed the 3D bipedal DNA walker amplification strategy to monitor the platelet-derived growth factor BB (PDGF-BB). Specifically, blue emission Cu NCs with low consumption, biocompatibility and numerous resources, act as well-overlapped donors and significantly improve the ECL efficiency of Ru(dcbpy)32+. More impressively, the intra-molecular ECL-RET of Cu NC-Ru endowed a better and more stable ECL signal by reducing the electron-transfer distance and decreasing the energy loss. Furthermore, 3D bipedal DNA walker amplification was employed to efficiently convert the target PDGF-BB into numerous DNA strands, achieving sensitive target amplification. By virtue of such design, the constructed aptasensor exhibited a sensitive and selective assay for PDGF-BB with a detection range from 0.01 pM to 10 nM and a detection limit of 3.3 fM. The intramolecular ECL-RET and 3D bipedal DNA walker amplification strategy designed in this study will provide valuable insight into promising ultrasensitive ECL bioanalysis.

Dynamic Metal-Iodide Bonds in a Tetracoordinated Cadmium-Based Metal-Organic Framework Boosting Efficient CO2 Cycloaddition under Solvent- and Cocatalyst-Free Conditions.

Due to the inherent thermodynamic stability and kinetic inertness of CO2, heterogeneous catalytic conversion of CO2 to cyclic carbonates often requires harsh operating conditions, high temperature and high pressure, and the addition of cocatalysts. Therefore, the development of efficient heterogeneous catalysts under cocatalyst-free and mild conditions for CO2 conversion has always been a challenge. Herein, an infrequent tetracoordinated Cd-MOF was synthesized and used to catalyze CO2 cycloaddition reactions efficiently without the addition of any cocatalyst, and its catalytic mechanism was systematically investigated through a series of experiments, including fluorescence analysis, X-ray photoelectron spectroscopy, microcalorimetry, and density functional theory (DFT) calculation. Cd-MOF features a 3D supermolecule structure with 1D 11.6 × 7.7 Å2 channels, and the abundant Lewis acid/base and I- sites located in the confined channel boost efficient CO2 conversion with a maximum yield of 98.2% and a turnover number value of 1080.11 at 60 °C and 0.5 MPa, far surpassing most pristine MOF-based catalytic systems. A combined experimental and DFT calculation demonstrates that the exposed Cd(II) Lewis acid sites rapidly participate in coordination to activate the epoxides, and the resulting large steric hindrance facilitates leaving of the coordinated iodide ions in a reversibly dynamic fashion convenient for the rate-determining step ring-opening as a strong nucleophile. Such a pristine MOF catalyst with self-independent catalytic ring-opening overcomes the complicated operation limitation of the traditional cocatalyst-free MOF systems based on encapsulating/postmodifying cocatalysts, providing a whole new strategy for the development of simple, green, and efficient heterogeneous catalysts for CO2 cycloaddition.

In Situ Ligand Formation in the Synthetic Processes from Mononuclear Dy(III) Compounds to Binuclear Dy(III) Compounds: Synthesis, Structure, Magnetic Behavior, and Theoretical Analysis.

Guided by the self-assembled process and mechanism, the strategy of in situ Schiff base reaction would be capable of bringing a feasible method to construct and synthesize lanthanide compounds with distinct structures and magnetic properties. A mononuclear Dy(III) compound was synthesized through a multidentate Schiff base ligand and a chelating ß-diketonate ligand, which was named as [Dy(L)(bppd)]·CH3OH [1; H2L = N,N'-bis(2-hydroxy-5-methyl-3-formylbenzyl)-N,N'-bis(pyridin-2-ylmethyl)ethylenediamine and bppd = 3-bis(pyridin-2-yl)propane-1,3-dione]. Furthermore, a new binuclear Dy(III) compound, [Dy2(H2Lox)(bppd)3]·8CH3OH [2; H4Lox = N,N'-bis[2-hydroxy-5-methyl-3-(hydroxyiminomethyl)benzyl]-N,N'-bis(pyridin-2-ylmethyl)ethylenediamine], was obtained via an in situ synthetic process. Under similar synthetic conditions, [Dy(L)(ctbd)] [3; ctbd = 1-(4-chlorophenyl)-4,4,4-trifluoro-1,3-butanedione] and [Dy2(H2Lox)(ctbd)3]·CH3OH·C4H10O (4) were synthesized by modifying the ß-diketonate ligand and in situ Schiff base reaction. Compound 3 is a mononuclear configuration, while compound 4 exhibits a binuclear Dy(III) unit. Therein, formylbenzyl groups of H2L in 1 and 3 were changed to (hydroxyiminomethyl)benzyl groups in 2 and 4, respectively. In isomorphous 2 and 4, two Dy(III) centers are connected through two phenol O- atoms of the H2Lox2- ligand to form a binuclear structure. Eight-coordinated Dy(III) ions with different distortions can be observed in 1-4. The crystals of 1 and 3 suffered dissolution/precipitation to obtain 2 and 4, respectively. The relationship between the structure and magnetism in compounds 1-4 was discussed through the combination of structural, experimental, and theoretical investigations. Especially, the rates of quantum tunneling of magnetization of 1-4 were theoretically predicted and are consistent with the experimental results. For 2 and 4, the theoretically calculated dipolar parameters Jdip are consistent with the experimental observation of weak ferromagnetic coupling.

Solvent-Free Lithium/Sodium-Based Metal-Organic Frameworks with Versatile Nitrogen-Rich Ligands: Insight for the Design of Promising Superheat-Resistant Explosives.

Energetic metal-organic frameworks (EMOFs) are very promising as heat-resistant explosives, affording both thermal stability and energy properties. In this work, the self-assembly of high-energy nitrogen-rich linkers with nontoxic alkali-metal lithium/sodium leads to four new solvent-free EMOFs. Because of unparalleled decomposition temperature (Tdec = 403 °C) and heats of detonation (3.475 kcal·g-1), a 3D Li(I)-EMOF can be considered to be a superheat-resistant explosive candidate.

Tailoring Electronic Structure and Size of Ultrastable Metalated Metal-Organic Frameworks with Enhanced Electroconductivity for High-Performance Supercapacitors.

Utilization of metal-organic frameworks (MOFs) as electrodes for energy storage/conversion is challenging because of the low chemical stability and poor electrical conductivity of MOFs in electrolytes. A nanoscale MOF, Co0.24 Ni0.76 -bpa-200, possessing ultrahigh stability with uncommon semiconductor behavior (σ=4.2×10-3  S m-1 ) was fabricated. The MOF comprises a robust hydrophobic paddlewheel and an optimized Co/Ni ratio, with consequent control over MOF size and the degree of conjugation of the coligand. A DFT study revealed that appropriate Ni2+ doping reduces the activation energy of the system, thus providing a higher carrier concentration, and the strongly delocalized N-donor ligand notably increases the metal-ligand orbital overlap to achieve efficient charge migration, leading to continuous through-bond (-CoNi-N-CoNi-)∞ conduction paths. These structural features endow the MOF with a good cycling stability of 86.5 % (10 000 cycles) and a high specific capacitance of 1927.14 F g-1 among pristine MOF-based electrodes.

Suppressed Jahn-Teller Distortion in MnCo2 O4 @Ni2 P Heterostructures to Promote the Overall Water Splitting.

Jahn-Teller distortion in cobalt based spinel electrocatalysts causes poor activity and stability in potentially promising catalysts for water splitting. Here, a novel strategy to resolve this problem by interface engineering is reported, in which, Jahn-Teller distortion in MnCo2 O4 is significantly suppressed by in situ growth Ni2 P nanosheets onto the MnCo2 O4 . The significance of interface engineering in suppressing Jahn-Teller distortion of Mn3+ is further investigated by X-ray photoelectron spectroscopy, the resulting increased catalytic activity and the effects of suppressed distortion demonstrated by density functional theory calculations. The resulting MnCo2 O4 @Ni2 P heterostructures exhibit superior electrocatalytic activity for the both oxygen evolution reaction and hydrogen evolution reaction with small overpotentials of 240 and 57 mV at 10 mA cm-2 , respectively. Furthermore, the heterogeneous composite electrode demonstrates a superior current density of 10 mA cm-2 at a voltage of 1.63 V with excellent durability in a water splitting cell.

A Silylene-Germylene Molecule Containing a SiI -GeI Single Bond.

The first isolable silylene-germylene complex 5 was assembled by a salt metathesis reaction between the germylene anion 3 and the N-heterocyclic chlorosilylene 4, and structurally characterized. The central structure of 5 demonstrates a remarkable gauche-bent geometry with the silylene and germylene units, which are interconnected by a Si-Ge bond with a length of 2.4498(9) Å. This value is not only perceptibly longer than the distances known in doubly bonded germasilenes, and also slightly longer than those in germylsilanes. The DFT calculations on 5 confirmed a nearly nonpolar SiI -GeI single-bond nature and its bonding orbital, as well as the aromaticity of the C3 NGe-rings in 3 and 5. The latter increases the molecular stability of 3 and 5, and makes the preparation of silylene-germylene complex 5 a reality.

A Trinuclear Zinc Coordination Cluster Exhibiting Fluorescence, Colorimetric Sensitivity, and Recycling of Silver Ion and Detection of Cupric Ion.

The detection and reusage of transition-metal ions play a crucial role in human health and environmental protection. Recently, various analytical methods and substances have been successfully applied to probe or sense silver ions; however, rare representative examples have been presented regarding the simultaneous detection of silver and silver recycling with the elemental silver powder form. Herein, an unparalleled sensing mechanism for silver ions and recycling silver in its elemental form is exemplified by a fluorescent trinuclear zinc coordination cluster possessing the dual function of colorimetric sensing of silver and responding cupric ions. A Schiff-base-based trinuclear zinc coordination cluster, 1, with formula Zn3(L1)2(CH3COO)2(H2O)2, has been successfully synthesized by the initial exploration of multidentate ligand H2L1-((E)-2,4-di-tert-butyl-6-((2-hydroxy-3-methoxybenzy-lidene)amino)phenol) with various metal ions under self-assembly reactions. Complex 1 is highly fluorescent in solution and as a solid, in addition to acting as a fluorescence sensor toward AgI in ethanol media. Compound 1 displays distinctive sensing of AgI through the fluorescence quenching effect at 576 nm and signal augment at 446 nm over 11 kinds of cations in the absence of interference. The proposed sensing mechanism is attributed to the ligands in 1 which interact with AgI; the ligands undergo oxidation cyclization reaction, leading to the formation of 2 with the formula Zn3(L2)4(CH3COO)2·2CH3CH2OH·H2O, and AgI reduction to elemental Ag powder. Compound 1 presents specific selectivity and sensitivity for AgI in ethanolic solution with a detection limit of 0.1722 µM. The orange color of 1 changes to colorless during the mixing of a small amount of AgI, revealing its potential practical application in naked-eye detection of AgI. Furthermore, 2 exhibits obvious fluorescence emission at 448 nm (λex = 380 nm) and selectively responds to CuII over 11 kinds of metal ions with the fluorescence "turn-off" owing to the formation of 3 in ethanolic solution; it also has a detection limit of 0.0226 µM.

An Inconspicuous Six-Coordinate Neutral DyIII Single-Ion Magnet with Remarkable Magnetic Anisotropy and Stability.

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(Cy3PO)2I3(CH3CN)] with a certain degree of stability exhibiting a huge thermal barrier of 1062 K and hysteresis loops open up to 9 K. Through the elaborate reduction of ligand field strength, an apparent strongly axial crystal field is provided which elicits prominent crystal-field splitting and high axiality with the thermally activated relaxation via the third-excited Kramers' doublet. Moreover, the profound influence of strong equatorial ligand substitution on the electronic structure and relaxation pathway is clearly explored in DyIII analogues. The result suggests the great potential of the reducing the transverse ligand field in the improvement of SMMs performance.

A Tetra-amido-Protected Ge5-Spiropentadiene.

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 Å), 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.

Capping N-Donor Ligands Modulate the Magnetic Dynamics of DyIII ß-Diketonate Single-Ion Magnets with D4d Symmetry.

A family of four mononuclear DyIII ß-diketonate complexes with formulas [Dy(tmhd)3 (Br2 -bpy) (1), [Dy(tmhd)3 (Br-bpy)] (2), [Dy(tmhd)3 (dppz)] (3), and [Dy(tmhd)3 (mcdpq)] (4) (tmhd=2,2,6,6-tetramethyl-3,5-heptanedione, Br2 -bpy=5,5'-dibromo-2,2'-bipyridine, Br-bpy=5-bromo-2,2'-bipyridine, dppz=dipyrido [3,2-a:2',3'-c]phenazine, mcdpq=2-methoxyl-3-cyanodipyrido[3,2-f:2,3'-h]quinoxaline) were prepared by modifying the capping N-donor coligands. DyIII centers in these complexes feature an N2 O6 octacoordinate environment with distorted square-antiprismatic D4d symmetry. Magnetic investigations evidenced single-ion magnet behavior in all complexes with energy barriers Ueff of 42.10 (1), 61.47, (2), 77.53 (3), and 2.51 K (4) in the absence of static field, as well as 206.03 (1), 224.13 (2), 247.76 (3), and 49.70 K (4) under applied dc field (Hdc =1500 Oe for 1 and 2; Hdc =1200 Oe for 3 and 4). The different natures of the N-donor ligands induce changes in both the coordination geometry and their intermolecular interactions, which severely impact their magnetic dynamics. The disparities in their magnetic behaviors and the uniaxial anisotropies are also explained and substantiated by theoretical calculations.

Regulation of Substituent Effects on Configurations and Magnetic Performances of Mononuclear DyIII Single-Molecule Magnets.

A series of mononuclear DyIII compounds, [Dy(tmpd)3(4,4'-dmpy)] (1), [Dy(tffb)3(4,4'-dmpy)] (2), [Dy(tffb)3(5,5'-dmpy)] (3), and [Dy(tmpd)3(5,5'-dmpy)] (4) [tmpd = 4,4,4-trifluoro-1-(4-methoxyphenyl)-1,3-butanedione, tffb = 4,4,4-trifluoro-1-(4-fluorophenyl)-1,3-butanedione, 4,4'-dmpy = 4,4'-dimethyl-2,2'-bipyridyl, and 5,5'-dmpy = 5,5'-dimethyl-2,2'-bipyridyl], have been synthesized by modifying ß-diketonate ligands and capping N-donor co-ligands. DyIII ions in 1-4 possess N2O6 octacoordinated environments. Compounds 1 and 2 exhibit distorted trigonal dodecahedron configurations, while 3 and 4 display distorted square antiprismatic configurations. Systematic investigations of the alternating current measurements indicate the different magnetic relaxation dynamics with energy barriers (Ueff) of 66 K (1, 45 cm-1), 189 K, (2, 131 cm-1), 115 K (3, 79 cm-1), and 205 K (4, 142 cm-1). To deeply understand their different magnetic behaviors, the magnetic anisotropies of 1-4 were studied by ab initio calculations. From ab initio calculations, the energies of the first excited state (KD1) are consistent with the experimental Ueff under zero direct current field. Compound 4 presents the largest Ueff because of the smallest gX,Y and µQTM as well as the most strong axial crystal field parameters (CFPs) among compounds 1-4. The M versus H data exhibit butterfly-shaped hysteresis loops at 2 K for 1-4. The different coordination geometries, the magnetic dynamics, the electrostatic repulsion, and CFPs result from the different substituent effects of ligands, including the electronic effect, the steric effect, and the positions of substituted groups.

A Robust TbIII-MOF for Ultrasensitive Detection of Trinitrophenol: Matched Channel Dimensions and Strong Host-Guest Interactions.

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.

Concise Chemistry Modulation of the SMM Behavior within a Family of Mononuclear Dy(III) Complexes.

By means of the facile chemistry, structural assembly, and transformation of four mononuclear Dy(III) complexes, Dy(bpad)3·CH3OH·H2O (1), Dy(bpad)2(H2O)2·NO3 (2), [Dy(bpad)2(tmhd)] (3), and [Dy(bpad)2(btfa)] (4) (Hbpad = N3-benzoylpyridine-2-carboxamidrazone, tmhd = 2,2,6,6-tetramethylheptane-3,5-dione, btfa = 3-benzoyl-1,1,1-trifluoroacetone), with distinct architectures and local symmetries were established. The disparity of the coordination geometries around the Dy(III) ion among these complexes impacts the strength of the crystal field and the local tensor of anisotropy ( D) of each Dy site and their relative orientations, therefore giving rise to diverse SIM behaviors with distinguishing relaxation energy barriers of 106.93 K for 1, 52.55 K for 2, 48.16 K for 3, and 51.41 K for 4. The differences of the magnetic property and the magnetic anisotropy for four complexes have been explained by ab initio calculations, which are corresponding to the experimental results.

GeI-GeI Coupling Reaction Induced by a Mixture of CoBr2 and a Seven-Membered N-Heterocyclic Carbene.

A new digermylene has been synthesized through the reaction of a six-membered cyclic radical germylene precursor with a mixture of CoBr2 and a seven-membered N-heterocyclic carbene. The density functional theory simulation on the geometry of the digermylene agrees well with the experimental X-ray diffraction result. The digermylene possesses the shortest GeI-GeI bond [2.4853(6) Å] compared to the known singly bonded analogues, which can be attributed to σ → π* conjugation. In addition, it is revealed that a stable dative bond cannot form for the reductive radical germylene with the oxidative metal centers.