Dinuclear Structure Research Articles

Multifunctional Dinuclear Dy-Based Coordination Complex Showing Visible Photoluminescence, Single-Molecule Magnet Behavior, and Proton Conduction.

A new Dy-based complex, [Dy2(phen)4(PAA)4](ClO4)2 (1), was obtained by using 4-hydroxyphenyl acetate (HPAA) as a ligand and 1,10-phenanthroline as an auxiliary ligand. Complex 1 shows a dinuclear structure and a 2D supramolecular layer constructed by π-π stacking interactions. The complex displays a characteristic Dy(III) emission. Moreover, magnetic susceptibility measurements revealed that 1 exhibits a single-molecule magnet (SMM) behavior. In addition, it also shows a proton conductivity of 1.08 × 10-5 S cm-1 under 353 K and 100% relative humidity conditions, which is mainly assigned to H-bonded networks formed by the undeprotonated and uncoordinated phenolic groups of HPAA ligands and guest water molecules. Remarkably, 1 is the first example of a dinuclear complex showing photoluminescence, SMM behavior, and proton conduction.

Synthesis, structural characterization, DNA interaction, dye adsorption properties and theoretical studies of copper (II) carboxylates

Two new copper (II) carboxylates viz. [Cu2(μ–2-chlorobenzoato-O,O')4(2-methoxybenzaldehyde)2] (1) and [Cu(μ–3,5-dinitrobenzoato-CO,O)(μ–3,5-dinitrobenzoato-NO,O)][Cu2(μ–3,5-dinitrobenzoato-CO,O′)](μ1MeOH)2 (2) containing 2-chlorobenzoic acid and 3,5-dinitrobenzoic acid respectively were synthesized, and characterized by elemental analyses, spectroscopic methods, topological analysis and single crystal XRD studies. Moreover, the synthesized complexes have been screened for the DNA binding ability through UV-Visible and fluorescence spectroscopy indicating moderately strong non-intercalative mode of interaction. Structural studies reveals that compound 1 possesses dinuclear paddle-wheel structure whereas compound 2 is 3D polymer. Asymmetric/monoclinic unit of compound 2 contains a mononuclear unit in combination with a dinuclear entity. DFT calculations combined with QTAIM and NCI plot computational tools have been used to analyze their solid-state supramolecular assemblies focusing on the role of halogen···halogen interactions in 1 and π-hole O···N pnictogen bonding in 2 involving the nitro groups. Finally, the dye adsorption property of the complexes was studied to ascertain their efficacy in removal of toxic dye molecules from aqueous medium. Compound 2 exhibits moderate dye removal efficiency.

Structural investigations and reactivity of cobalt(II)–disulfide compounds

Controlling the bio-inspired redox conversion of Co(II)–disulfide compounds to their related Co(III)–thiolate complexes is a perplexing task as the factors triggering this reaction are not fully understood. Three disulfide ligands 2,2′–disulfanediylbis(N,N-bis((3,5–dimethyl-1H–pyrazol–1–yl)methyl)ethan-1-amine) (LmpzSSLmpz), 3,3′-disulfanedylbis(N,N-bis(pyridin-2-ylmethyl)propan-1-amine) (LpSSLp), and 2,2′-disulfanediylbis(N,N-bis(6-methylpyridin-2–ylmethyl)ethan-1–amine) (L3SSL3) with different chain lengths and pyrazole or pyridine groups were reacted with cobalt(II) salts and the resulting complexes were studied for their potential to form Co(III)–thiolate complexes. Crystal structures of [Co2(LmpzSSLmpz)(Br)4] [1Br], [Co2(LmpzSSLmpz)(NCS)4] [1NCS], [Co2(LpSSLp)(NCS)4] [2NCS], and [Co2(L3SSL3)(Cl)4] [3Cl] show that generally the disulfide sulfur donors do not coordinate to the cobalt(II) centers, resulting in dinuclear structures containing two 5-coordinate cobalt centers. However, a unique asymmetric structure is found in [1Br] in which one of the sulfur atoms coordinates to one of the cobalt ions. Thiocyanate–induced Co(III)–thiolate formation in the presence of either ligand LmpzSSLmpz or LpSSLp is evidently unsuccessful, as Co(II)–disulfide complexes were obtained. The reaction of the Co(II)–disulfide complexes with 8-quinolinol suggest that redox conversion to Co(III)–thiolate complexes may take place, but the reactions are not clean.

Part‐per‐million catalysis of azide‐alkyne cycloaddition reaction in water using a new ferromagnetic μ1,1‐N3 bridged dinuclear Cu(II) complex

An original copper(II) dimeric compound formulated as [Cu2(μ1,1‐N3)2L2(N3)2].2CHCl3 (1), with L = 2,6‐pyridinedicarboxaldehydebis(p‐iodophenyl‐imine), has been synthesized and characterized. Single crystal X‐ray structural characterization revealed that this complex displays a centrosymmetric dinuclear structure in which the two Cu(II) centers are connected by double symmetric μ1,1 (end‐on, EO) azido bridges, generating distorted octahedral CuN6 coordination geometry. Magnetic susceptibility measurements indicate a ferromagnetic Cu···Cu coupling with J = 26.7 cm−1 (J being the parameter of the exchange Hamiltonian H = −2JS1S2). The catalytic properties of complex 1 have been evaluated in the one‐pot azide‐alkyne cycloaddition reaction in water without any additional reducing agents or bases. As expected, the absence of any catalyst did not lead to product formation, whereas when complex 1 was introduced as catalyst, the reaction led to the desired product with different chemical yields (10–98%), for which the highest one (98%) corresponds to the reaction performed in the presence of 125 ppm of 1 in water at 90 C. These optimized parameters have been then taken into account to extend the initial reaction based on benzyl chloride and simple alkyne to different substituted benzyl chloride and alkyne molecules.

Heavy Alkali Metal Manganate Complexes: Synthesis, Structures and Solvent-Induced Dissociation Effects.

Rare examples of heavier alkali metal manganates [{(AM)Mn(CH2 SiMe3 )(N'Ar )2 }∞ ] (AM=K, Rb, or Cs) [N'Ar =N(SiMe3 )(Dipp), where Dipp=2,6-iPr2 -C6 H3 ] have been synthesised with the Rb and Cs examples crystallographically characterised. These heaviest manganates crystallise as polymeric zig-zag chains propagated by AM⋅⋅⋅π-arene interactions. Key to their preparation is to avoid Lewis base donor solvents. In contrast, using multidentate nitrogen donors encourages ligand scrambling leading to redistribution of these bimetallic manganate compounds into their corresponding homometallic species as witnessed for the complete Li - Cs series. Adding to the few known crystallographically characterised unsolvated and solvated rubidium and caesium s-block metal amides, six new derivatives ([{AM(N'Ar )}∞ ], [{AM(N'Ar )⋅TMEDA}∞ ], and [{AM(N'Ar )⋅PMDETA}∞ ] where AM=Rb or Cs) have been structurally authenticated. Utilising monodentate diethyl ether as a donor, it was also possible to isolate and crystallographically characterise sodium manganate [(Et2 O)2 Na(n Bu)Mn[(N'Ar )2 ], a monomeric, dinuclear structure prevented from aggregating by two blocking ether ligands bound to sodium.

Triply bridged binuclear lanthanides-Zwitterion complexes: synthesis and characterization of (Gd(III), Nd(III), Sm(III)) complexes

2,2'-((1E,1'E)-(Butane-1,4-diylbis (azanylylidene))bis (methanylylidene)) diphenol zwitterion (L) (4′) was prepared by treatment of two equiv. of (3-(2-furyl)acrolein) (1) with one equiv. of 1,4-butanediamine (2) in refluxing ethanol through an intramolecular Diels-Alder reaction. Three new lanthanide compounds based on (4′), [Ln2(NO3)4(H2O)2L3]·2NO3 (5) (a, Ln = Gd; b, Ln = Nd; c, Ln = Sm), have been obtained and further characterized by elemental analysis, conductivity, magnetic measurements, FT-IR, powder X-ray and thermogravimetric analysis. Compounds 5a–c exhibit a discrete dinuclear structure constructed by three ligands coordinating two Ln3+ ions. The oxygen atoms of the diphenol are involved in the coordination of 5, while the nitrogen atoms of the imines are not involved. Hypersensitive transitions could be observed at 877, 807, 753, 588, and 522 nm in the UV–visible absorption spectrum of the neodymium complex 5 b, corresponding to 4I9/2→4F3/2 (877 nm); 4I9/2→4F5/2, 2H9/2 (807 nm); 4I9/2→4S3/2, 4F7/2 (753 nm); 4I9/2→2G7/2, 4G5/2 (588 nm); 4I9/2→4G9/2 4G7/2, and 2K13/2 (522 nm), respectively. Emission spectra of the ligand and its samarium complex 5c revealed characteristic luminescence within the visible region with the emission of the samarium complex being relatively red shifted.

Polyethylene Waxes with Short Chain Branching via Steric and Electronic Tuning of an 8-(Arylimino)-5,6,7-trihydroquinoline-nickel Catalyst

Ten examples of nickel(II) halide complexes [8-{N(2,4-(C15H13)2-6-RC6H2N)}C9H8N]NiBr2 [R = Me (Ni1), Et (Ni2), iPr (Ni3), Cl (Ni4), or F (Ni5)] and [8-{N(2,4-(C15H13)2-6-RC6H2N)}C9H8N]NiCl2 [R = Me (Ni6), Et (Ni7), iPr (Ni8), Cl (Ni9), or F (Ni10)], each incorporating a sterically encumbered N,N-chelating 8-[2,4-bis(dibenzocycloheptyl)-6-R-phenylimino]-5,6,7-trihydroquinoline ligand, are disclosed. Full details for the preparation of these complexes as well as the zinc-mediated synthesis of precursor ligands L1–L5 are given. Structural characterization of Ni3(H2O), Ni6, Ni7(H2O), and Ni8(H2O) reveals halide-bridged dinuclear structures of the type (N,N)NiX(μ-X)2NiX(N,N) with the ortho-substituted dibenzocycloheptyl groups providing steric protection to each metal center. In the presence of ethylaluminum dichloride (EtAlCl2) or methylaluminoxane (MAO), Ni1–Ni10 displayed high activities for ethylene polymerization [≤6.17 × 106 g of PE (mol of Ni)−1 h–1 for Ni6/EtAlCl2 at 20 °C], generating low-molecular weight polyethylene waxes. Notably, catalysts incorporating a 6-alkyl group (Me, Et, or iPr) as the N-aryl substituent proved to be more active than their 6-halide (Cl or F) counterparts and formed relatively higher-molecular weight polymers (Mw range of 9.1–22.9 kg mol–1) with a narrow dispersity. Moreover, analysis of these waxes by 13C nuclear magnetic resonance spectroscopy showed that they typically possessed short chain branching (>83% methyl) with branching densities of 79–90 branches per 1000 Cs. In addition, chain end analysis revealed the presence of both vinyl (−CH═CH2) and internal vinylene (−CH═CH−) functional groups, highlighting the role of both β-H elimination and isomerization.

Multi-component self-assembled heteroleptic Cu(I) complex with defective coordination site as a fluorescent probe to detect Zn2+

Heteroleptic copper(I)–phosphine complexes have attracted considerable attention due to their diverse structures and photophysical properties. In this work, a novel heteroleptic binuclear copper (I) complex C1·2BF4ˉ was designed and synthesized by using hexaazatriphenylene (L1) and 4, 5-Bis(diphenylphosphino)-9, 9-dimethylxanthene (dppd) as functional ligands. Such dinuclear structure with defective site was fully characterized by NMR, single-crystal X-ray diffraction analysis, and electron spray ionization mass spectrometry (ESI-MS). UV-vis and fluorescence spectrum revealed that the well-defined Cu(I) complex had a green emission at 518 nm in acetonitrile solution, and a red emission at 824 nm in the solid state. The DFT calculation demonstrated that the energy gap between LUMO and HOMO orbitals reached 1.20 eV. Furthermore, such heteroleptic Cu(I) complex showed high sensitivity and selectivity towards Zn2+ in acetonitrile solution in “turn-on” mode, which can be attributed to the coordination interaction between Zn2+ and defective binding site of probe C1·2BF4−. The LOD for Zn2+ was calculated to be 0.298 µM, and the reversible “on-off” fluorescence sensing behavior can be recovered by alternative treatment with EDTA tetrasodium and Zn2+ salts in solution. The Cu(I) complex probe C1·2BF4ˉ had reversible redox property with weak electrochemical responses towards Zn2+ ions.

Antimicrobial activities of two 1‐D, 2‐D, and 3‐D mononuclear Mn (II) and dinuclear Bi (III) complexes: X‐ray structures, spectroscopic, electrostatic potential, Hirshfeld surface analysis, and time‐dependent/density functional theory studies

AbstractTwo mononuclear and dinuclear octahedral complexes, [Mn(L1)2Cl2] (1) and [Bi2(L2)2Cl8] (2) (L1 = 2‐(2‐pyridyl)‐4‐methyl‐1,2‐dihydroquinazoline‐N3‐oxide, L2 = 2‐(3‐pyridyl)‐4‐methyl‐1,2‐dihydroquinazoline‐N3‐oxide) were prepared by natural volatilization method. The ligands and both complexes were compared with spectroscopic methods, as well as characterized by elemental analysis. The photoluminescence behaviors of both complexes in different solvents were also investigated. The coordination possibility of ligands toward Mn (II)/Bi (III) was verified using X‐ray crystallography, and it revealed that the ratio of ligand to metal was 2:1 in 1, whereas 1:1 in 2. The adjacent molecules of six‐coordinated complex 1 constituted an infinite 1‐D chain, 2‐D network, and ladder‐like 3‐D supramolecular frameworks. Most strikingly, hexa‐coordinated complex 2 with dinuclear structure formed an infinite 1‐D chain, 2‐D layered and meter‐shaped 3‐D supramolecular skeleton. Density functional theory (DFT) calculation was used to optimize the geometry of complexes, compute the electrostatic potential diagrams, and evaluate the HOMO‐LUMO energy gap. The electronic transition simulated through time‐dependent (TD)‐DFT level of calculation rationalized the experimental data. The antibacterial properties of all compounds were evaluated against Gram‐positive and Gram‐negative bacterial strains. In addition, the Hirshfeld surface was utilized to quantify some hydrogen bonding interactions and their contributions.

Construction of two Ln(III)2 (Ln = Dy and Er) compounds by a polydentate Schiff-based ligand: Structure and remarkable single-molecule magnet behavior

Two novel dinuclear lanthanide-based compounds, [Ln2(dbm)2(L)2(C2H5OH)2] (Ln = Dy (1) and Er (2)) were successfully self-assembled by using a polydentate Schiff-based ligand. The structures and magnetic behaviors of the obtained products 1 and 2 were investigated in detail. Compound 1 is a dinuclear cluster with space group P21/c, while compound 2 has a space group P-1. Compounds 1 and 2 both have a centrosymmetric dinuclear structure, each central LnIII ion is eight-coordinated and the two central ions are bridged together by two μ2O carbonyl oxygen atoms. Magnetic analysis suggests that compound 1 has ferromagnetic coupling between two adjacent DyIII ions. Remarkable slow-relaxation behaviors of magnetization were observed in 1 under 0 dc filed, giving a value of ΔE/kB = 91.88 K with τ0 = 3.65 × 10−8 s.

Bis[μ3-2-(pyridin-3-yl)acetato-κ3 O:O:O']bis-[μ2-2-(pyridin-3-yl)acetato-κ2 O:O']bis-[chlorido-(1,10-phenanthroline-κ2 N,N')dysprosium(III)

The title DyIII complex, [Dy2(C7H6NO2)4Cl2(C12H8N2)2] or [Dy2(μ 3-PAA)4(Cl)2(phen)2] (PAA = 3-pyridyl-acetate, phen = 1,10-phenanthroline), obtained by reaction of Dy(ClO4)3, 3-pyridyl-acetic acid ligands and 1,10-phenanthroline, exhibits a dinuclear structure. Adjacent binuclear dimers are further connected via face-to-face π-π stacking inter-actions resulting in supra-molecular chains along the c-axis direction.

3-Pyridylacetic-Based Lanthanide Complexes Exhibiting Magnetic Entropy Changes, Single-Molecule Magnet, and Fluorescence.

Four complexes from lanthanides, 3-pyridylacetate, and 1,10-phenanthroline, formulated as [Ln2(3-PAA)2(μ-Cl)2(phen)4](ClO4)2 [Ln = Gd(1), Dy(2), Eu(3), Tb(4), 3-PAA = 3-pyridylacetic acid, phen = 1,10-phenanthroline], were obtained. The four compounds were characterized by IR spectra, thermogravimetric analyses, powder X-ray diffraction, and single-crystal X-ray diffraction. Compounds 1–4 are isomorphous, and they have a dinuclear structure. Magnetic studies reveal that 1 shows the magnetocaloric effect with −ΔSmmax = 19.03 J kg–1 K–1 at 2 K for ΔH = 5 T, and 2 displays a field-induced single-molecule magnet with Ueff = 19.02 K. The photoluminescent spectra of 3 and 4 exhibit strong characteristic emission, which demonstrate that the ligand-to-EuIII/TbIII energy transfer is efficient.

P-Block metal complexes with bis(pyrazol-1-yl)acetato ligands.

The hetereoscorpionate ligands bis(pyrazol-1-yl)acetic acid (Hbpza) and bis(3,5-dimethylpyrazol-1-yl)acetic acid (Hbdmpza) are reacted with [Sn(OAc)2] or [Sn(acac)2] to yield the corresponding Sn(II) complexes. A single crystal X-ray determination for the in solution monomeric complex [Sn(bpza)2] (1a) revealed a dinuclear molecular structure [Sn2(bpza)4] (1b), with κ3-N,N,O-coordinated bpza ligands at each of the Sn(II) and two bpza ligands μ-bridging between the Sn(II) centres. The molecular structure of [Sn(bdmpza)2] (2) exhibits a homoleptic bisligand complex with both ligands displaced by the free electron pair, which is proven by DFT calculations. Oxidation of complex 2 in an attempt to synthesize a homoleptic Sn(IV) complex leads to the formation of [Sn(bdmpza)F3] (3). In addition, homoleptic bisligand gallium complexes [Ga(bdmpza)2][ClO4] (4) and [Ga(bpza)2][GaCl4] (5) were prepared and characterized by 71Ga NMR and IR spectroscopy as well as by X-ray crystallography.

Synthesis, crystal structures and characterization of Nickel(II) complexes with dithiobenzoate derivatives

New nickel(II) complexes with dithiobenzoate ligands, [NiII(Me-dtb)2] and [NiII(Oct-dtb)2]2 (Me-dtb = 4-methyl-dithiobenzoate and Oct-dtb = 4-octyl-dithiobenzoate), were synthesized and structurally characterized using X–ray diffraction analysis. [NiII(Me-dtb)2] has a mononuclear structure, including a nickel(II) ion with a square planar coordination geometry, and [NiII(Oct-dtb)2]2 has a dinuclear structure connected by weak Ni•••S interactions in the apical position of the nickel ion. The solutions of these complexes show strong light absorption at approximately 600 nm with a dark blue color. To reveal the electronic states and mechanism of the light absorption of Ni(II)- dithiobenzoate complexes, optimization of the ground-state molecular structures and excited-state calculations for [NiII(dtb)2] (dtb = dithiobenzoate) and [NiII(Me2dtc)2] (Me2dtc = dimethyl-dithiocarbamate) were performed by DFT/B3LYP method and TD-DFT/CAM-B3LYP method, respectively.

Construction of novel hexanuclear Co(II) and dinuclear Ni(II) bis(salamo)‐type complexes

Two novel homomultinuclear complexes [Co6(L)2(μ‐OAc)4]·2CHCl3·CH3COCH3 (1) and [Ni2(L)(H2O)2(Py)2]·2CHCl3 (2) with a newly designed rigid bis(salamo)‐type tetraoxime ligand (H4L) were synthesized and characterized by elemental analyses, Fourier transform infrared (FT‐IR) spectra, UV–Vis absorption spectra, and X‐ray single‐crystal diffractions. Complex 1 is a novel triple‐decker symmetrical six‐core cluster structure with twofold axis and inversion center. The Co(II) atoms were sandwiched between the bis(salamo)‐type ligands and possess two different geometries of distorted tetragonal pyramid and octahedron, respectively. Complex 2 possesses a dinuclear structure and the Ni(II) atoms are located in the N2O2 cavities of the ligand, and axial coordination atoms come from the coordinated water and pyridine molecules. Both Ni(II) atoms adopt distorted octahedral geometries. The interactions were quantitatively determined by Hirshfeld surfaces analyses of complexes 1 and 2. The coordination ratios were determined by studying the fluorescence properties of complexes 1 and 2. The results of fluorescence titration experiment show that the metals to ligand binding ratios are 6:2 and 2:1 for complexes 1 and 2, respectively.

Synthesis, Structure, and Photophysical Properties of Yellow-Green and Blue Photoluminescent Dinuclear and Octanuclear Copper(I) Iodide Complexes with a Disilanylene-Bridged Bispyridine Ligand.

The synthesis, structural, and photophysical investigations of CuI complexes with a disilanylene-bridged bispyridine ligand 1 are herein presented. Dinuclear (2) and ladder-like (3) octanuclear copper(I) complexes were straightforwardly prepared by exactly controlling the ratio of CuI/ligand 1. Single-crystal X-ray analysis confirmed that dinuclear complex 2 had no apparent π…π stacking whereas octanuclear complex 3 had π…π stacking in the crystal packing. In the solid state, the complexes display yellow-green (λem = 519 nm, Φ = 0.60, τ = 11 µs, 2) and blue (λem = 478 nm, Φ = 0.04, τ = 2.6 µs, 3) phosphorescence, respectively. The density functional theory calculations validate the differences in their optical properties. The difference in the luminescence efficiency between 2 and 3 is attributed to the presence of π…π stacking and the different luminescence processes.

Electrochemical sensing of hydrogen peroxide on a carbon paste electrode modified by a silver complex based on the 1,3-bis(1H-benzimidazole-2-yl)propane ligand

Abstract A new carbon paste electrode (Ag-CPE) modified with a nitrogen heterocyclic silver(I) complex, [Ag2(BBP)2](pic)2·CH3OH (BBP = 1,3-bis(1H-benzimidazol-2-yl)propane, pic = picrate), was developed as a highly sensitive and simple electrochemical sensor for the determination of hydrogen peroxide. The Ag(I) complex was prepared by an interface reaction and characterized by elemental analysis, IR and UV/Vis spectra and single crystal X-ray diffraction. The Ag(I) complex shows a dinuclear cluster structure, which is formed by two BBP ligands bridging two Ag (I) centers and an Ag–Ag interaction (d Ag–Ag = 3.0875 Å). Cyclic voltammetry and chronoamperometry studies showed that the electrochemical sensing performance of Ag-CPE for H2O2 was improved in 0.2 m phosphate buffer solution (PBS, pH = 6). The electrochemical H2O2 sensor Ag-CPE exhibits a wide linear detection range from 0.5 to 4.0 mm and a lower detection limit of 0.39 μm with a relatively high sensitivity of 6.77 μA mm −1. Moreover, the sensor also shows good anti-interference properties and stability. The results prove that the Ag(I) complex based on the bis(benzimidazole) ligand may be an efficient component of electrode materials.

Synthesis, crystal structure, optoelectric properties and theoretical study of three perovskite-like iodobismuthate charge-transfer salts based on butylpyridinium

Three new perovskite-like iodobismuthate hybrids with two butylpyridinium cations, namely (BPY)3(Bi2I9) (1), (BPY)5(Bi2I11) (2) and (BMPY)3(Bi2I9) (3) (BPY ​= ​1-butylpyridinium, BMPY ​= ​1-butyl-4-methylpyridinium), were synthesized by reacting of BiI3 and butylpyridinium. Single-crystal X-ray diffraction analysis revealed that these three hybrids exhibit two types of di-nuclear cluster structures, face-sharing Bi2I93− cluster for 1 and 3, and vertex-sharing Bi2I115− cluster for 2. Their optical band gaps were determined as 2.06 ​eV(1), 2.01 ​eV(2), 1.86 ​eV(3), respectively. DFT calculation reveals that their valence band tops and conduction band bottoms are composed of the states of iodine and pyridinium cations, respectively. Therefore these materials were classified as charge-transfer salts. Compared with similar iodobismuthates, their band gaps are significantly reduced. In addition, it is found that the band gaps should be affected by supramolecular interaction between cations in 2 and also by the conformational multiplicity of cations in structure 3. Photocurrent response test showed that these charge-transfer salts have rapid and consistent photocurrent response. This result indicated their potential applications as a photocatalyst or a photovoltaic absorber.

Manipulating a series of Ln-based helix chains or dinuclear complexes by designing two types of Schiff-based ligands: Structure and magnetic properties

As an important means of regulating ligands, steric hindrance effect is always the first choice to construct structures. It is rare to assemble complexes with different topological and structural types by increasing or decreasing the steric hindrance of ligands and to regulate their properties. Here, we successfully obtained two types of lanthanide structures [Ln(H2L1)(NO3)3]n (1: Dy; 2: Gd, H2L1 ​= ​6,6'-((1E,1′E)-((2,2-dimethylpropane-1,3-diyl)bis(azanylylidene))bis(methanylylidene))bis(2-methoxyphenol)) and [Ln2(H2L2)3(NO3)6]·(CH3CN)x·(CH3OH)y (3: Dy, x ​= ​3, y ​= ​0; 4: Gd, x ​= ​y ​= ​2, H2L2 ​= ​6,6'-((1E,1′E)-((2,2-dimethylpropane-1,3-diyl)bis(azanylylidene))bis(methanylylidene))bis(2-ethoxyphenol)), which are controlled by ligands with the steric hindrance effect. For the all structures, the ligands are distorted when they coordinate with lanthanide ions, which make the ligands form helical structures around Ln(III) ions. For chains 1 and 2, there is a single twisted ligand bridging to form a one-dimensional spiral chain between the Ln(III) ion and the Ln(III) ion. But for complexes 3 and 4, there is a helical dinuclear structure formed by the cross-bridging of a double twisted ligand between the Ln(III) ion and the Ln(III) ion. AC magnetic susceptibilities show that chain 1 is a single-molecule magnet (SMM), which exhibits obviously frequency dependent behavior with the energy barriers of 39.6 (3) K and 44.6 (5) K, but complex 3 shows field-induced single-molecule magnetic behavior. The magnetocaloric effects (MCEs) show that chain 2 has bigger value of S than that of complex 4.

Atomically Precise Dinuclear Site Active toward Electrocatalytic CO2 Reduction.

The development of atomically precise dinuclear heterogeneous catalysts is promising to achieve efficient catalytic performance and is also helpful to the atomic-level understanding on the synergy mechanism under reaction conditions. Here, we report a Ni2(dppm)2Cl3 dinuclear-cluster-derived strategy to a uniform atomically precise Ni2 site, consisting of two Ni1-N4 moieties shared with two nitrogen atoms, anchored on a N-doped carbon. By using operando synchrotron X-ray absorption spectroscopy, we identify the dynamically catalytic dinuclear Ni2 structure under electrochemical CO2 reduction reaction, revealing an oxygen-bridge adsorption on the Ni2-N6 site to form an O-Ni2-N6 structure with enhanced Ni-Ni interaction. Theoretical simulations demonstrate that the key O-Ni2-N6 structure can significantly lower the energy barrier for CO2 activation. As a result, the dinuclear Ni2 catalyst exhibits >94% Faradaic efficiency for efficient carbon monoxide production. This work provides bottom-up target synthesis approaches and evidences the identity of dinuclear sites active toward catalytic reactions.