Novel Copper(II) Complexes with Dipinodiazafluorene Ligands: Synthesis,Structure, Magnetic and Catalytic Properties

The reactions of CuX₂ (X = Cl, Br) with dipinodiazafluorenes yielded four new complexes [CuX₂L₁]₂ (X = Cl (1), Br (2), L₁ = (1R,3R,8R,10R)-2,2,9,9-Tetramethyl-3,4,7,8,9,10-hexahydro-1H-1,3:8,10-dimethanocyclopenta [1,2-b:5,4-b’]diquinolin-12(2H)-one) and [(CuX₂)₂L₂]n (X = Cl (3), Br (4), L₂ = (1R,3R,8R,10R,1’R,3’R,8’R,10’R)-2,2,2’,2’,9,9,9’,9’-Octamethyl-1,1’,2,2’,3,3’,4,4’,7,7’,8,8’,9,9’,10,10’-hexadecahydro-1,3:1’,3’:8,10:8’,10’-tetramethano-12,12’-bi(cyclopenta [1,2-b:5,4-b’]diquinolinylidene). The complexes were characterized by IR and EPR spectroscopy, HR-ESI-MS and elemental analysis. The crystal structures of compounds 1, 2 and 4 were determined by X-ray diffraction (XRD) analysis. Complexes 1–2 have a monomeric structure, while complex 4 has a polymeric structure due to additional coordinating N,N sites in L₂. All complexes contain a binuclear fragment {Cu₂(μ-X)_2×2} (X = Cl, Br) in their structures. Each copper atom has a distorted square-pyramidal coordination environment formed by two nitrogen atoms and three halogen atoms. The Cu-N_ax distance is elongated compared to Cu-N_eq. The EPR spectra of compounds 1–4 in CH₃CN confirm their paramagnetic nature due to the d⁹ electronic configuration of the copper(II) ion. The magnetic properties of all compounds were studied by the method of static magnetic susceptibility. For complexes 1 and 2, the effective magnetic moments are µ_eff ≈ 1.87 and 1.83 µ_B (per each Cu²⁺ ion), respectively, in the temperature range 50–300 K, which are close to the theoretical spin value (1.73 µ_B). Ferromagnetic exchange interactions between Cu(II) ions inside {Cu₂(μ-X)₂X₂} (X = Cl, Br) dimers (J/k_B ≈ 25 and 31 K for 1 and 2, respectively) or between dimers (θ′ ≈ 0.30 and 0.47 K for 1 and 2, respectively) were found at low temperatures. For compounds 3 and 4, the magnetic susceptibility is well described by the Curie–Weiss law in the temperature range 1.77–300 K with µ_eff ≈ 1.72 and 1.70 µ_B for 3 and 4, respectively, and weak antiferromagnetic interactions (θ ≈ −0.4 K for 3 and −0.65 K for 4). Complexes 1–4 exhibit high catalytic activity in the oxidation of alkanes and alcohols with peroxides. The maximum yield of cyclohexane oxidation products reached 50% (complex 3). Based on the data on the study of regio- and bond-selectivity, it was concluded that hydroxyl radicals play a decisive role in the oxidation reaction. The initial products in reactions with alkanes are alkyl hydroperoxides.     

Heteroligand α-Diimine-Zn(II) Complexes with O,N,O′- and O,N,S-Donor Redox-Active Schiff Bases: Synthesis,Structure and Electrochemical Properties

A number of novel heteroligand Zn(II) complexes (1–8) of the general type (Lⁿ)Zn(NN) containing O,N,O′-, O,N,S-donor redox-active Schiff bases and neutral N,N′-chelating ligands (NN) were synthesized. The target Schiff bases LⁿH₂ were obtained as a result of the condensation of 3,5-di-tert-butyl-2-hydroxybenzaldehyde with substituted o-aminophenols or o-aminothiophenol. These ligands with combination with 2,2′-bipyridine, 1,10-phenanthroline, and neocuproine are able to form stable complexes upon coordination with zinc(II) ion. The molecular structures of complexes 4∙H₂O, 6, and 8 in crystal state were determined by means of single-crystal X-ray analysis. In the prepared complexes, the redox-active Schiff bases are in the form of doubly deprotonated dianions and act as chelating tridentate ligands. Complexes 6 and 8 possess a strongly distorted pentacoordinate geometry while 4∙H₂O is hexacoordinate and contains water molecule coordinated to the central zinc atom. The electrochemical properties of zinc(II) complexes were studied by the cyclic voltammetry. For the studied complexes, O,N,O′- or O,N,S-donor Schiff base ligands are predominantly involved in electrochemical transformations in the anodic region, while the N,N′-coordinated neutral nitrogen donor ligands demonstrate the electrochemical activity in the cathode potential range. A feature of complexes 5 and 8 with sterically hindered tert-butyl groups is the possibility of the formation of relatively stable monocation and monoanion forms under electrochemical conditions. The values of the energy gap between the boundary redox orbitals were determined by electrochemical and spectral methods. The parameters obtained in the first case vary from 1.97 to 2.42 eV, while the optical bang gap reaches 2.87 eV.     

QSAR Modeling,Molecular Docking and Cytotoxic Evaluation for Novel Oxidovanadium(IV) Complexes as Colon Anticancer Agents

Four new drug-based oxidovanadium (IV) complexes were synthesized and characterized by various spectral techniques, including molar conductance, magnetic measurements, and thermogravimetric analysis. Moreover, optimal structures geometry for all syntheses was obtained by the Gaussian09 program via the DFT/B3LYP method and showed that all of the metal complexes adopted a square-pyramidal structure. The essential parameters, electrophilicity (ω) value and expression for the maximum charge that an electrophile molecule may accept (ΔN_max) showed the practical biological potency of [VO(CTZ)₂] 2H₂O. The complexes were also evaluated for their propensity to bind to DNA through UV–vis absorption titration. The result revealed a high binding ability of the [VO(CTZ)₂] 2H₂O complex with K_b = 1.40 × 10⁶ M⁻¹. Furthermore, molecular docking was carried out to study the behavior of the VO (II) complexes towards colon cancer cell (3IG7) protein. A quantitative structure–activity relationship (QSAR) study was also implemented for the newly synthesized compounds. The results of validation indicate that the generated QSAR model possessed a high predictive power (R² = 0.97). Within the investigated series, the [VO(CTZ)₂] 2H₂O complex showed the greatest potential the most selective compound comparing to the stander chemotherapy drug.     

含磺基苯甲酸及联吡啶钌配合物的合成、结构和催化苯甲硫醚氧化研究

利用水热方法合成了一个三联吡啶钌磺基苯甲酸配合物,[Ru(2,2′-bipy)3](3-Hsb)(3-sb).5H2O(1)(2,2′-bipy为2,2′-联吡啶;3-sb2-为3-磺基苯甲酸根离子),对配合物进行了元素分析、红外、紫外、荧光和差热热重表征,解析了配合物的晶体结构。晶体结构解析表明:配合物1是阴离子-阳离子型化合物,阴离子与水分子形成三维有孔洞的氢键网络,阳离子占据这些孔洞。电化学性质测试表明:氧化还原是一个单电子可逆的过程,对应的可逆对为Ru(Ⅳ)/Ru(Ⅲ),E1/2=1.350 V。室温苯甲硫醚氧化催化实验表明:钌配合物与酸结合具有较高的催化活性与亚砜选择性。     

Novel redox active rhodium(iii) complex with bis(arylimino)acenaphthene ligand: synthesis,structure and electrochemical studies

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两个2,4-二羟基苯甲醛缩甘氨酸配合物的合成、结构及其对醇的选择性氧化催化

合成和表征了两个2,4-二羟基苯甲醛缩甘氨酸(H₃L)席夫碱配合物[Cu(Py)₂(HL)] (1)和[Zn(Py)₃(HL)]·2Py(Py=吡啶) (2),并通过X射线单晶衍射分析确定了其结构。配合物1通过分子间的O-H…O氢键形成了一维链状结构,配合物2通过分子间的O-H…O和C-H…O氢键形成了二维网状结构。重要的是,配合物1在醇的选择性氧化反应中显示出了良好的催化效率(转化率高达94.8%,选择性高达98.3%)。     

两个2,4-二羟基苯甲醛缩甘氨酸配合物的合成、结构及其对醇的选择性氧化催化

合成和表征了2个2,4-二羟基苯甲醛缩甘氨酸(H₃L)席夫碱配合物[Cu(Py)₂(HL)] (1)和[Zn(Py)₃(HL)]·2Py(Py=吡啶) (2),并通过X射线单晶衍射分析确定了其结构.配合物1通过分子间的O-H…O氢键形成了一维链状结构,配合物2通过分子间的O-H…O和C-H…O氢键形成了二维网状结构.重要的是,配合物1在醇的选择性氧化反应中显示出了良好的催化效率(转化率高达94.8%,选择性高达98.3%).     

Metal-Bonded Redox-Active Triarylamines and Their Interactions: Synthesis,Structure, and Redox Properties of Paddle-Wheel Copper Complexes

Four new triphenylamine ligands with different substituents in the para position and their corresponding copper(II) complexes are reported. This study includes their structural, spectroscopic, magnetic, and electrochemical properties. The complexes possess a dinuclear copper(II) paddle-wheel core, a building unit that is also common in metal-organic frameworks. Electrochemical measurements demonstrate that the triphenylamine ligands and the corresponding complexes are susceptible to oxidation, resulting in the formation of stable radical cations. The square-wave voltammograms observed for the complexes are similar to those of the ligands, except for a slight shift in potential. Square-wave voltammetry data show that, in the complexes, these oxidations can be described as individual one-electron processes centered on the coordinated ligands. Spectroelectrochemistry reveals that, during the oxidation of the complexes, no difference can be detected for the spectra of successively oxidized species. For the absorption bands of the oxidized species of the ligands and complexes, only a slight shift is observed. ESR spectra for the chemically oxidized complexes indicate ligand-centered radicals. The copper ions of the paddle-wheel core are strongly antiferromagnetic coupled. DFT calculations for the fully oxidized complexes indicate a very weak ferromagnetic coupling between the copper ions and the ligand radicals, whereas a very weak antiferromagnetic coupling is found among the ligand radicals.     

新型苯并咪唑类配体配合物的合成及其性能

以苯并咪唑（HL¹）和3,6 二氯哒嗪在钠催化下反应制得配体3-氯-6-(苯并咪唑-1-基)哒嗪(L²）;采用溶液法和水热法,L¹分别与含有银、铜过渡金属盐反应合成了3种新的有机金属苯并咪唑配合物［AgL¹］_n(1),［Cu₄(HL¹)₄(O)(Cl)₆］(2)和{［Cu(HL¹)₂］·SiF₆}(3);采用溶液法,L²与Zn(NO₃)₂·6H₂O经配位反应合成了配合物{［Zn(L²)₃(NO₃)］NO₃}(4),其结构经IR,元素分析和X-射线单晶衍射表征。结果表明：1通过苯并咪唑桥连形成一维链状结构,2由苯并咪唑和氯离子桥接形成四核结构,3和4均显示一个单核结构,3的金属中心原子采用二配位构型,4的金属中心原子采用四配位构型。此外,研究了配体HL¹与1,及配体L²与4的荧光性能。结果表明：与HL¹相比,1的最大发射波长发生了红移;而4相对于配体L²其最大发射峰发生明显蓝移。     

A Novel Family of Cage-like (CuLi,CuNa, CuK)-phenylsilsesquioxane Complexes with 8-Hydroxyquinoline Ligands: Synthesis,Structure, and Catalytic Activity

The first examples of metallasilsesquioxane complexes, including ligands of the 8-hydroxyquinoline family 1–9, were synthesized, and their structures were established by single crystal X-ray diffraction using synchrotron radiation. Compounds 1–9 tend to form a type of sandwich-like cage of Cu₄M₂ nuclearity (M = Li, Na, K). Each complex includes two cisoid pentameric silsesquioxane ligands and two 8-hydroxyquinoline ligands. The latter coordinates the copper ions and corresponding alkaline metal ions (via the deprotonated oxygen site). A characteristic (size) of the alkaline metal ion and a variation of characteristics of nitrogen ligands (8-hydroxyquinoline vs. 5-chloro-8-hydroxyquinoline vs. 5,7-dibromo-8-hydroxyquinoline vs. 5,7-diiodo-8-hydroxyquinoline) are highly influential for the formation of the supramolecular structure of the complexes 3a, 5, and 7–9. The Cu₆Na₂-based compound 2 exhibits high catalytic activity towards the oxidation of (i) hydrocarbons by H₂O₂ activated with HNO₃, and (ii) alcohols by tert-butyl hydroperoxide. Studies of kinetics and their selectivity has led us to conclude that it is the hydroxyl radicals that play a crucial role in this process.     

Trapping of Ag+ into a Perfect Six-Coordinated Environment: Structural Analysis,Quantum Chemical Calculations and Electrochemistry

Self-assembly of (Bu₄N)₄[β-Mo₈O₂₆], AgNO₃, and 2-bis[(2,6-diisopropylphenyl)-imino]acenaphthene (dpp-bian) in DMF solution resulted in the (Bu₄N)₂[β-{Ag(dpp-bian)}₂Mo₈O₂₆] (1) complex. The complex was characterized by single crystal X-ray diffraction (SCXRD), X-ray powder diffraction (XRPD), diffuse reflectance (DR), infrared spectroscopy (IR), and elemental analysis. Comprehensive SCXRD studies of the crystal structure show the presence of Ag⁺ in an uncommon coordination environment without a clear preference for Ag-N over Ag-O bonding. Quantum chemical calculations were performed to qualify the nature of the Ag-N/Ag-O interactions and to assign the electronic transitions observed in the UV–Vis absorption spectra. The electrochemical behavior of the complex combines POM and redox ligand signatures. Complex 1 demonstrates catalytic activity in the electrochemical reduction of CO₂.     

对-氢醌金属配合物：合成，结构及电化学性质

A new Chromium(Ⅲ) complex, [Cr(Hcah)(H₂O)₂]·2H₂O, where H₄cah=2-[N,N-bis(carboxymethyl)aminome-thyl] hydroquinone (H₄cah), has been synthesized and characterized using X-ray diffraction single crystal structure determination, IR and elemental analysis. The complex belongs monoclinic, space group P2₁/c, with a=0.792 05(4) nm, b=1.008 63(6) nm, c=1.920 40(10) nm, β=93.069(4)°, V=1.531 98(14) nm³, and Z=4. The cyclic voltametric analysis shows that the electron transfer in the electrode reaction is irreversible for Cr(Ⅲ)/Cr₂O₇^2- and Cr(Ⅲ)/Cr(Ⅱ) redox couples while reversible for process of interchange from p-Hydroquinone to p-semiquinones. CCDC: 666208.     

Synthesis, Crystal Structure and Electrochemical Studies of Two Novel Zn(II) Complexes of Phthalic Acid and Imidazole Derivatives

Two novel coordination polymers [Zn(pa)(vim)2]n (1) and [Zn(pa)(eim)2]n (2) (pa＝phthalic acid dianion, vim＝1-vinyl-1H-imidazole, eim＝1-ethyl-1H-imidazole) have been synthesized and their structures characterized by X-ray single crystal diffractometry and elemental analysis. Both of the complexes consist of [Zn(L)2] (L＝vim for 1; eim for 2) entities linked into polymeric zigzag chains along the crystallographic c-axis by bridging phthalate anions in the μ2-1,2 coordination mode. The coordination around each Zn(II) atom is tetrahedral. There are only van der Waals interactions between the chains in 1, while the three-dimensional network in 2 is assembled by C—H…O contacts. The electrochemical studies reveal that redoxes of Zn2+/Zn in complexes 1 and 2 are irreversible processes.     

基于吡啶二羧酸配体的稀土配合物的合成、结构及性质

以2,6-二甲基吡啶-3,5-二羧酸（H₂L₁）为主配体,1,10-菲咯啉（L₂）为辅配体,分别与五水合硝酸镝、六水合硝酸铽及六水合硝酸铕通过水热法合成[Dy₂（L₁）₃（L₂）₂]_n（1）、{[Tb₂（L₁）₃（L₂）₂]·5H₂O}_n（2）和{[Eu₂（L₁）₃（L₂）₂]·5H₂O}_n（3）三种配合物。通过单晶X射线衍射、红外光谱、荧光光谱和热重分析对其结构进行了表征与性质研究。结果表明,配合物1~3均以稀土离子为金属节点连接配体L₁^2-和L₂,形成无限延伸的一维链状结构。     

新型钒卤代过氧化物酶模型化合物的合成结构及仿生催化活性

模拟卤代过氧化物酶活性中心钒的配位环境设计合成了新的蝎型聚吡唑硼酸盐钒氧化合物VO(HB(3,5-Me<,2> pz)<,3>)(3,5-Me<,2>pz)(HOOCCH<,2>CH<,2>COO)(1)和VO(HB(3,5-Me<,2>pz)<,3>)(3,5-Me<,2> pz)(C<,5>H<,4>NCOO)(2...     

α-Diimine Cisplatin Derivatives: Synthesis,Structure, Cyclic Voltammetry and Cytotoxicity

Three new Pt(II) complexes [(dpp-DAD)PtCl₂] (I), [(Mes-DAD(Me)₂)PtCl₂] (II) and [(dpp-DAD(Me)₂)PtCl₂] (III) were synthesized by the direct reaction of [(CH₃CN)₂PtCl₂] and corresponding redox-active 1,4-diaza-1,3-butadienes (DAD). The compounds were isolated in a single crystal form and their molecular structures were determined by X-ray diffraction. The purity of the complexes and their stability in solution was confirmed by NMR analysis. The Pt(II) ions in all compounds are in a square planar environment. The electrochemical reduction of complexes I–III proceeds in two successive cathodic stages. The first quasi-reversible reduction leads to the relatively stable monoanionic complexes; the second cathodic stage is irreversible. The coordination of 1,4-diaza-1,3-butadienes ligands with PtCl₂ increases the reduction potential and the electron acceptor ability of the DAD ligands. The synthesized compounds were tested in relation to an adenocarcinoma of the ovary (SKOV3).     

Heteroleptic and Homoleptic Iron(III) Complexes with a Tris(N-Heterocyclic Carbene) Borate Ligand: Synthesis,Characterization, and Catalytic Application

Heteroleptic and homoleptic iron(III) complexes supported by a tris(N-heterocyclic carbene) borate ligand have been prepared and crystallographically characterized. The strong electron-donating character of the tris(carbene) donor was revealed by UV-vis absorption spectroscopy and electrochemical measurements combined with quantum chemical calculations. The catalytic activity of each complex was evaluated in cyclohexane oxidation reaction using meta-chloroperoxybenzoic acid (=mCPBA) as an oxidant, and both complexes show high catalytic activity and selectivity with TON=∼350 and A/(K+L)=8–10. Mechanistic studies suggested that radical-chain processes are involved in the reaction due to mCPBA acting as a one-electron oxidant, concomitant with the pathway of metal-based reactive species. Moreover, it was found that the homoleptic and heteroleptic complexes differed significantly in the involvement of metal-based active species, with the homoleptic complex exhibiting more metal-based reactions.     

Synthesis,Structure, and Catalytic Activity of Cyclometalated Iridium Complexes with a Bidentate POC Ligand

Synthesis, characterization and catalytic activity of cyclometalated iridium complexes with a bidentate POC ligand is presented. Metalation of POC-H (di-tert-butyl(phenoxy)phosphane) with [Ir(COD)Cl]₂ proceeded rapidly at room temperature and afforded mixture of (POC)(POC-H)IrHCl ( 1 a ) and (POC)(COD)IrHCl ( 1 b ), from which complexes (POC)(L)IrHCl where L=PPh₃ ( 1 c ), bipyridine ( 1 d ) and [2,2′-bipyridine]-6,6′-diol ( 1 e ) were prepared through ligand exchange. The compounds were tested in acceptorless dehydrogenation of 1-phenylethanol and transfer dehydrogenation of ethanol in a context of comparison with pincer counterparts (POCOP)IrHCl and (PCN)IrHCl. An attempt to prepare a dihydride complex from 1 e led to dimeric complex [(POC)(bipy-diol−)IrH]₂ ( 3 ) that could explain the low activity of 1 e . DFT studies provided insight into POC-H vs POCOP-H metalation mechanism.     

Flavin Derivatives with Tailored Redox Properties: Synthesis,Characterization, and Electrochemical Behavior

This study establishes structure–property relationships for four synthetic flavin molecules as bioinspired redox mediators in electro‐ and photocatalysis applications. The studied flavin compounds were disubstituted with polar substituents at the N1 and N3 positions (alloxazine) or at the N3 and N10 positions (isoalloxazines). The electrochemical behavior of one such synthetic flavin analogue was examined in detail in aqueous solutions of varying pH in the range from 1 to 10. Cyclic voltammetry, used in conjunction with hydrodynamic (rotating disk electrode) voltammetry, showed quasi‐reversible behavior consistent with freely diffusing molecules and an overall global 2e^?, 2H⁺ proton‐coupled electron transfer scheme. UV/Vis spectroelectrochemical data was also employed to study the pH‐dependent electrochemical behavior of this derivative. Substituent effects on the redox behavior were compared and contrasted for all the four compounds, and visualized within a scatter plot framework to afford comparison with prior knowledge on mostly natural flavins in aqueous media. Finally, a preliminary assessment of one of the synthetic flavins was performed of its electrocatalytic activity toward dioxygen reduction as a prelude to further (quantitative) studies of both freely diffusing and tethered molecules on various electrode surfaces.     

A Series of Novel Pentagonal-Bipyramidal Erbium(III) Complexes with Acyclic Chelating N3O2 Schiff-Base Ligands: Synthesis,Structure, and Magnetism

A series of six seven-coordinate pentagonal-bipyramidal (PBP) erbium complexes, with acyclic pentadentate [N₃O₂] Schiff-base ligands, 2,6-diacetylpyridine bis-(4-methoxybenzoylhydrazone) [H₂DAPMBH], or 2,6-diacethylpyridine bis(salicylhydrazone) [H₄DAPS], and various apical ligands in different charge states were synthesized: [Er(DAPMBH)(C₂H₅OH)Cl] (1); [Er(DAPMBH)(H₂O)Cl]·2C₂H₅OH (2); [Er(DAPMBH)(CH₃OH)Cl] (3); [Er(DAPMBH)(CH₃OH)(N₃)] (4); [(Et₃H)N]⁺[Er(H₂DAPS)Cl₂]⁻ (5); and [(Et₃H)N]⁺[Y₀.₉₅Er₀.₀₅(H₂DAPS)Cl₂]⁻ (6). The physicochemical properties, crystal structures, and the DC and AC magnetic properties of 1–6 were studied. The AC magnetic measurements revealed that most of Compounds 1–6 are field-induced single-molecule magnets, with estimated magnetization energy barriers, U_eff ≈ 16–28 K. The experimental study of the magnetic properties was complemented by theoretical analysis based on ab initio and crystal field calculations. An experimental and theoretical study of the magnetism of 1–6 shows the subtle impact of the type and charge state of the axial ligands on the SMM properties of these complexes.