Nickel(II) complexes with mono(imino)pyrrole ligands: preparation,structure and ethylene polymerization behavior

A series of unsymmetrical mono(imine)pyrroles (L1–L3) were synthesized by microwave irradiation from 2-acetylpyrrole and a series of dimethylanilines with two methyl groups at different positions on the aniline ring. A simplified synthetic method was initiated to prepare the corresponding nickel complexes NiL₂ (1–3) with direct condensation of mono(imine)pyrrole and nickel chloride. The compounds were determined using a suite of techniques (i.e. ¹H NMR, ¹³C NMR, IR, EA, MS). L1–L3 and 3 were further characterized by X-ray crystal diffraction. The structure of 3 showed that the ligand chelated to nickel with 2?:?1 M ratio, in spite of a 1?:?1 rate of charge. Application of 1–3 in ethylene polymerization indicated that mono(imino)pyrrole nickel complexes showed low activities. The polymerization reaction time and temperature, as well as the ligand structure, influenced the catalytic performance to some extent. Experimental data showed higher activity as –CH₃ on the aniline ring is closer to the imine group.     

Structure-based linker optimization of 6-(2-cyclohexyl-1-alkyl)-2-(2-oxo-2-phenylethylsulfanyl)pyrimidin-4(3H)-ones as potent non-nucleoside HIV-1 reverse transcriptase inhibitors

In continuation of our efforts toward the discovery of potent HIV-1 NNRTIs with diverse structures,a series of novel S-DACO analogues of 6-(2-cyclohexyl-1-allkyl)-2-(2-oxo-2-phenyl-ethylsulfanyl)pyrimidin-4(3 H)-ones were designed,synthesized and evaluated for their antiviral activities in MT-4 cells.Most of these new compounds showed moderate to good activities against wild type HIV-1 with IC_(50) values ranging from 7.55 μmol/L to 0.018 μmol/L.Among them,compound 5 c was identified as the most promising inhibitor against HIV-1 replication with an IC_(50)=0.018 μmol/L,CC_(50)=194 μmol/L,and SI=12791,which was much more potent than the reference drugs NVP and DLV and comparable to AZT and EFV.In addition,5 c also exhibited improved activity against double mutant HIV-1 strain RES056 compared to that of the reference drugs NVP/DLV and DB02.The preliminary structure-activity relationship(SAR) and molecular modeling studies were also discussed,which provides some useful indications for guiding the further rational design of new S-DACO analogues.     

Effect of lipophilicity of wingtip groups on the anticancer potential of mono N‐heterocyclic carbene silver(I) complexes: Synthesis,crystal structures and in vitro anticancer study

A series of symmetrically n ‐alkyl‐substituted mono benzimidazolium salts with steady increase in n ‐alkyl chain length have been prepared by stepwise N ‐alkylation resulting in salts ( 1 – 8 ). The mono N‐heterocyclic carbene (NHC)–Ag(I) complexes ( 9 – 16 ) derived from the respective salts were readily accessible by in situ deprotonation using Ag₂O. All the salts and the complexes were characterized using Fourier transform infrared, ¹H NMR, ¹³C NMR and elemental analyses. Furthermore, the structures of salts 3 and 7 and complex 16 were elucidated using X‐ray crystallography, which established that this mono NHC–Ag(I) complex has a linear bis‐carbene arrangement (C₂–Ag). The proligands and the respective Ag(I) complexes were studied for their in vitro anticancer potential against human colon cancer cell line (HCT‐116) using 5‐fluorouracil as a standard. From the IC₅₀ values of all the tested compounds, it can be postulated that there is an influential relationship between the increase in chain length of the wingtip n ‐alkyl groups and the anticancer potential. The proligands 4 – 8 and their respective complexes 12 – 16 with long n ‐alkyl chain lengths (n  = 6–10) showed better IC₅₀ values (0.3–3.9 μM) than the standard drug with the complexes displaying markedly better antiproliferation activity against HCT‐116 cell line than the respective proligands and the standard drug (IC₅₀ = 10.2 μM).     

Structural studies of mono(pentamethylcyclopentadienyl)lanthanide complexes

The mono(pentamethylcyclopentadienyl) lanthanide complexes [(C₅Me₅)Yb(μ-I)(μ-η ⁵?: η ⁵-C₅Me₅)Yb(C₅Me₅)]_n (1), {[(C₅Me₅)Sm]₃(μ-Cl)₄(μ ₃-Cl)(μ ₃-OH)(THF)}₂ (2), {[(C₅Me₅)Sm]₂ (μ-OH)(μ-Cl)₄(μ ₃-Cl)Mg(THF)₂}₂ (3), [(C₅Me₅)₂Sm](μ-Cl)₆(μ ₃-Cl)₂(μ ₄-Cl)[(C₅Me₅)Sm]₄ (4), {[(C₅Me₅)Nd]₃(μ ₃-Cl)₄(μ ₄-Cl)₂(μ ₃-O₂CPh)₂K₂(η ⁶-C₇H₈)}₂ (5), [(C₅Me₅)Nd(C₈H₈)]₂(μ-dioxane) (6), [(C₅Me₅)Yb(MeO^tBu)]₂(μ-η ⁸?:?η ⁸-C₈H₈) (7), [(C₅Me₅)Dy(μ-I)₂]₃ (8), and [(C₅Me₅) Tm(MeCN)₆]I₂ (9), have been identified by X-ray crystallography. 1 is unusual in that it has a μ-η ⁵?:?η ⁵-C₅Me₅ ring that generates a local bent metallocene environment around ytterbium. Complexes 2–5 demonstrate the versatility of bridging chlorides in generating a variety of structures for mono(pentamethylcyclopentadienyl) lanthanide halides. Complex 6 shows how dioxane can generate a crystallographically-analyzable complex by bridging two mixed-ligand metallocene units that do not readily crystallize with THF. The structure of 7 shows how methyl tert-butyl ether (MTBE) ligates a lanthanide. Complex 8 is a trimeric cyclopentadienyl lanthanide halide unusual in that it has six bridging halides that roughly define a trigonal prism. Complex 9 constitutes an organometallic example of a lanthanide in which acetonitrile completely displaces iodide counterions.     

Synthesis and anti-HBV evaluation of mono L-amino acid ester,mono non-steroid anti-inflammation drug carboxylic ester derivatives of acyclonucleoside phosphonates简

A series of mono L-amino acid ester, mono non-steroid anti-inflammation drug(NSAID), carboxylic ester derivatives of acyclonucleoside phosphonates were prepared by using a ‘‘one pot synthesis' ' method and their in vitro anti-HBV activity were evaluated in HepG 2.2.15 cells. Compound 9a exhibited more potent anti-HBV activity and lower cytotoxicity than those of adefovir dipivoxil with IC50 and selective index(SI) values of 0.48 mmol/L and 763.72, respectively.     

Electrocatalytic Oxidation of Calcium Folinate on Carboxyl Graphene Modified CuxO/Cu Electrode

Carboxyl graphene modified Cu_xO/Cu electrode was fabricated. The bare copper electrode was firstly anodic polarized in 1.0 mol/L NaOH solution in order to get Cu_xO nanoparticles, then the carboxyl graphene (CG) was electrodeposited on the Cu_xO/Cu electrode by cyclic potential sweeping. The electrocatalytic oxidation behaviors of calcium folinate (CF) at the graphene modified Cu_xO/Cu electrode were investigated by cyclic voltammetry. A positive scan polarization reverse catalytic voltammetry was used to obtain the pure catalytic oxidation current. The graphene modified Cu_xO/Cu electrode was served as the electrochemical sensor of CF, a highly sensitivity of 22.0 μA·(μmol/μL)^-1cm^-2 was achieved, and the current response was linear with increasing CF concentration in the range of 2.0×10^-7 mol/L to 2.0×10^-5 mol/L, which crossed three orders of magnitude, and the detection limit was found 7.6×10^-8 mol/L (S/N=3). In addition, the proposed sensor was successfully applied in determination of CF in drug sample.     

Hydrogen Peroxide Sensor Based on Hemoglobin Immobilized on Glassy Carbon Electrode with SiO2 Nanoparticles/Chitosan Film as Immobilization Matrix

Abstract

A novel amperometric sensor of hydrogen peroxide was constructed. Hemoglobin (Hb) was successfully immobilized on nanometer‐sized SiO₂, which was supported by chitosan. Chitosan was acted as dispersant. The determination of hydrogen peroxide was performed in the presence of an electron mediator hydroquinone. Hb immobilized on the SiO₂/chitosan composite film displayed excellent electrocatalytical activity to the reduction of H₂O₂. The linear range of detection towards H₂O₂ was from 6.25×10^?7 to 1.63×10^?4mol/L with a detection limit of 1.8×10^?7mol/L (S/N=3). The apparent Michaelis‐Menten constant (K ^app _M) was found to be 0.75mmol/L.     

Synthesis,characterization, antibacterial,and cytotoxic activities of organotin(IV) complexes derived from N(4)-cyclohexylthiosemicarbazone: X-ray crystal structure of [Ph2SnCl(L)]

Reaction of organotin(IV) chloride(s) with 2-benzoylpyridine-N(4)-cyclohexylthiosemicarbazone, [HL] (1) yielded [MeSnCl₂(L)] (2), [BuSnCl₂(L)] (3), [Me₂SnCl(L)] (4), and [Ph₂SnCl(L)] (5). The ligand (1) and its organotin(IV) complexes have been characterized by CHN analyses, molar conductivity, UV-Vis, FT-IR, ¹H, ¹³C, and ¹¹⁹Sn NMR spectral studies. The molecular structure of 5 was also determined by X-ray diffraction. There are two independent molecules in the asymmetric unit and the central tin(IV) atom is six-coordinate in distorted octahedral geometry. The ligand (1) and complexes were screened for their in vitro antibacterial activities. The cytotoxic activities of 1–5 were tested against A2780 and A2780/Cp8 cancer cell lines. The compounds have better antibacterial activities than the free ligand; 2–5 are more potent cytotoxic agents than 1, while the diphenyltin(IV) 5 is more active with IC₅₀ values of 0.05 and 0.54?µmol?L^?1 against A2780 and A2780/Cp8 cell lines, respectively.     

Effect of LiClO4 on the radical polymerization of Di-2-[2-(2-methoxyethoxy)ethoxy]ethyl itaconate

The effect of LiClO₄ on the polymerization of di-2-[2-(2-methoxyethoxy)ethoxy]ethyl itaconate (DMEI) with dimethyl 2,2′-azobisisobutyrate (MAIB) was investigated in methyl ethyl ketone (MEK) kinetically and by ESR. The polymerization rate (R_p) at 50°C, where the concentrations of DMEI and MAIB were 1.00 and 5.00 × 10⁻² mol/L, increased with increasing [LiClO₄]. Marked acceleration was observed at higher [LiClO₄]s than 1.0 mol/L. The molecular weight of resulting polymer (ca. 10,000) was relatively insensitive to [LiClO₄], indicating occurrence of chain transfer. IR analysis of mixtures of LiClO₄/DMEI and LiClO₄/poly(DMEI) indicated complexation of LiClO₄ with DMEI and its polymer. The rate constants of propagation (k_p) and termination (k_t) were determined by ESR. k_p (1.7–10.5 L/mol s at 50°C) increased with [LiClO₄]. k_t (5.2–1.0 × 10⁴ L/mol s at 50°C) showed remarkable decrease at higher [LiClO₄]s than 1.0 mol/L. R_p of polymerization of equimolar complex of LiClO₄/DMEI with MAIB at 50°C in MEK was expressed by R_p = k[MAIB]^0.5[DMEI]^2.4. k_p increased and k_t decreased with [DMEI]. The activation energies of overall polymerization, propagation and termination were estimated to be 34.5, 8.0, and 59.4 kJ/mol. Copolymerization of DMEI with styrene was also profoundly affected by the presence of LiClO₄. Such large effects of LiClO₄ on the homo- and copolymerization of DMEI are explicable in term of association of LiClO₄-complexed DMEI monomers. © 1997 John Wiley & Sons, Inc.     

Electrochemistry and Electrocatalysis of a Nafion/Nano‐CaCO3/Hb Film Modified Carbon Ionic Liquid Electrode Using BMIMPF6 as Binder

In this paper a room temperature ionic liquid 1‐butyl‐3‐methylimidazolium hexafluorophosphate (BMIMPF₆) was used as binder for the construction of carbon ionic liquid electrode (CILE) and a new electrochemical biosensor was developed for determination of H₂O₂ by immobilization of hemoglobin (Hb) in the composite film of Nafion/nano‐CaCO₃ on the surface of CILE. The Hb modified electrode showed a pair of well‐defined, quasi‐reversible redox peaks with E_pa and E_pc as ?0.265 V and ?0.470 V (vs. SCE). The formal potential (E°′) was got by the midpoint of E_pa and E_pc as ?0.368 V, which was the characteristic of Hb Fe(III)/Fe(II) redox couples. The peak to peak separation was 205 mV in pH 7.0 Britton–Robinson (B–R) buffer solution at the scan rate of 100 mV/s. The direct electrochemistry of Hb in the film was carefully investigated and the electrochemical parameters of Hb on the modified electrode were calculated as α=0.487 and k_s=0.128 s^?1. The Nafion/nano‐CaCO₃/Hb film electrode showed good electrocatalysis to the reduction of H₂O₂ in the linear range from 8.0 to 240.0 μmol/L and the detection limit as 5.0 μmol/L (3σ). The apparent Michaelis–Menten constant (K_M^app) was estimated to be 65.7 μmol/L. UV‐vis absorption spectroscopy and FT‐IR spectroscopy showed that Hb in the Nafion/nano‐CaCO₃ composite film could retain its native structure.     

邻-(N-芳酰基-N-甲氨基苯)-二硫化合物的合成：通过N-甲基-2-单芳基苯并噻唑啉在溶剂中的自发偶联反应和它们的血管内皮生长因子抑制活性

N-甲基-2-单芳基苯并噻唑啉 (1) 在固体状态时可以稳定地储藏在空气中。但是,它们在不同溶剂中却表现出了不同的行为。在醇溶液或二甲亚砜-水的体系中,1相对稳定;而在其它有机溶剂如：丙酮,氯仿,二氯甲烷和乙酸乙酯等溶剂中,会发生自发偶联反应生成相应的邻-(N-芳酰基-N-甲氨基苯)-二硫化合物 (2)。对这些新的化合物 (1) 和 (2) 进行了体外人乳腺癌细胞 (MDA-MB-231) 血管内皮生长因子靶点筛选,大部分化合物都表现出了抑制活性。实验结果表明这两类化合物 (1) 和 (2) 作为血管内皮生长因子抑制剂值得进行深入研究。     

Two Rhodamine-based Turn on Chemosensors with High Sensitivity,Selectivity, and Naked-Eye Detection for Hg2+

Two novel rhodamine-based fluorescence enhanced molecular probes (RA₁ and RA₂) were synthesized, which were both designed as comparative fluoroionophore and chromophore for the optical detection of Hg²⁺. The recognizing behaviors were investigated both experimentally and computationally. They exhibited high selectivity and sensitivity for Hg²⁺ over other commonly coexistent metal ions in CH₃CN/H₂O (1:1, V/V) solution. Test shows that hydroxy benzene of rich electron was beneficial to the chelate of Hg²⁺ with sensors. The detection limit was measured to be at least 0.14 μmol/L. After addition of Hg²⁺, the color changed from colourless to pink, which was easily detected by the naked eye in both solution and hydrogel sensor.     

Electrocatalysis of Puerarin on a Nano-CeO2/MWCNTs Composite Modified Electrode and Its Determination in Pharmaceutical Preparations

A good route for the fabrication of CeO₂ nanoparticles (nano‐CeO₂)/multi‐walled carbon nanotubes (MWCNTs) modified glassy carbon electrodes (GCE) was proposed. MWCNTs are used to immobilize nano‐CeO₂. What′s more, with the addition of the MWCNTs, the agglomeration level of CeO₂ nanoparticles can be reduced, the extremely large surface area can be obtained and the electron transfer rate can be increased. The morphological characterization of nano‐CeO₂/MWCNTs was examined by scanning electron microscopy (SEM). The performances of the nano‐CeO₂/MWCNTs/GCE were characterized with cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and typical amperometric response (i‐t). The potential utility of the constructed electrodes was demonstrated by applying them to the analytical determination of puerarin concentration. The catalytic oxidation of puerarin has a better result on nano‐CeO₂/MWCNTs/GCE because of the synergistic effect of nano‐CeO₂ and MWCNTs. An optimized limit of detection of 8.0×10^?9 mol/L was obtained at a signal‐to‐noise ratio of 3 and with a fast response time (within 3 s). Additionally, the nano‐CeO₂/MWCNTs/GCE exhibited a wide linear range from 0.04 to 6.0 μmol/L and high sensitivity.     

手性化合物[Co(L/D-thr)3]·4.5H2O的合成、结构以及圆二色性

合成了2个基于手性配体L-和D-苏氨酸（L/D-thr）的Co（III）配合物的对应异构体[Co（L-thr）₃]·4.5H₂O（L-1）和[Co（L-thr）₃]·4.5H₂O（D-1）,并对2个化合物进行了单晶X射线衍射、红外、热重、紫外可见光谱以及CD谱性质研究。晶体结构分析表明,2个化合物分别结晶在四方晶系P4₃2₁2和P4₁2₁2手性空间群。固体CD谱测试进一步证实2个化合物具有手性。     

Ternary copper(II) complexes of aroylhydrazones and mono/bidentate heterocycles with different structures: synthesis,crystal structure and properties

Two mixed-ligand Cu(II) complexes, [CuL¹(Himdz] · CH₃OH (1) and [CuL²(phen)] · 0.5DMF (2), with different structures have been synthesized by using substituted aroylhydrazones, 5-bromo-salicylaldehyde-benzoylhydrazone (H₂L¹) and 5-bromo-salicylaldehyde-3,5-dimethoxy-benzoylhydrazone (H₂L²), and mono/bidentate heterocycles, imidazole (Himdz) and 1,10-phenanthroline (phen). Their crystal structures and spectroscopic properties have been studied. X-ray analysis show a distorted square-planar geometry for 1 and a distorted square-pyramidal geometry for 2, in which the chelating phen ligand displays axial-equatorial bonding. In both structures the ONO tridentate ligand occupies the basal plane. Self-assembly via O–H ··· N, N–H ··· O and C–H ··· O interactions lead to one-dimensional chain arrangement in 1 and 2.     

Transition metal chemistry of oxime-containing ligands,VI: magnetic and structural properties of mono (pyridine-2-aldoxime) dithiocyanato iron (II) and mono (6-methylpyridine-2-aldoxime) dithiocyanato iron (II) complexes

The complexes of pyridine-2-aldoxime (HPOX) and 6-methylpyridine-2-aldoxime (HMPX) with iron (II) thiocyanate of the type [Fe(L)(NCS)₂] (L=HPOX and HMPX) have been prepared and characterized. A study of X-ray, magnetic, vibrational spectra (conventional and far-infrared), electronic spectra andMössbauer spectra has indicated that these complexes have polymeric, pseudo octahedral, coordination geometry with linear bridging thiocyanate ligands. The electronic spectra of mono complexes show a larger, low symmetry, ligand field than that present in [Fe(L)₂(NCS)₂] complexes. UnperturbedMössbauer spectra show a large quadrupole splitting, E _Q, and smaller isomer shift values in these iron (II) thiocyanate complexes. The magnetically perturbedMössbauer spectra of these iron(II) thiocyanate complexes at room temperature show that the principal component of the electric field gradient tensor is positive and corresponds to ad _xy (⁵B₂) ground state.With 2 Figures     

Direct Electrochemistry of Horseradish Peroxidase Embedded in Nano－Fe304 Matrix on Paraffin Impregnated Graphite Electrode and Its Electrochemical Catalysis for H2O2

Fe3O4 particles coated with acrylic copolymer (ACP) of about 5--8 nm in diameter were synthesized and used for immobilization of horseradish peroxidase (HRP). Direct electrochemistry of HRP embedded in the nanosized Fe304 solid matrix modified paraffin impregnated graphite electrode (PIGE) was achieved,which is related to the heine Fe(Ⅲ)/Fe(Ⅱ) conversion of HRP. Cyclic voltammetry gave a pair of reproducible and welldefined redox peaks at about Ea of -0.295 V vs. SCE. The standard rate constant k, was determined as 2.7 s^-1. It demonstrated that the nano-Fe3O4 solid matrix offers a friendly platform to assemble the HRP protein molecules and enhance the electron transfer rate between the HRP and the electrode. UV-Vis absorption spectra and WrIR spectra studies revealed that the embedded HRP retained its native-like structure. The HRP/Fe3O4/PIGE showed a strong catalytic activity toward H2O2. The voltammetric response was a linear function of H2O2 concentration in the range of 10-140μmol/L with detection limit of 7.3 μmol/L (s/n = 3 ). The apparent Michaelis-Menten constant is calculated to be 0.42 mmol/L.     

Synthesis,biological evaluation and molecular docking studies of novel 2-(2-cyanophenyl)-N-phenylacetamide derivatives

A series of novel 2-(2-cyanophenyl)-N-phenylacetamide derivatives 3(a-u) were designed and synthesized via selective amidation of methyl-2-(2-cyanophenyl)acetates over amidine formation by using AlMe₃ as catalyst in good yields. All the newly synthesized derivatives were well characterized by ¹H NMR, ¹³C NMR, FTIR and HRMS spectral techniques. All the synthesized title compounds were evaluated for their in vitro anticancer activity against three cancer cell lines. Among all compounds, 3i (IC₅₀?=?1.20 μM, IC₅₀?=?1.10 μM), 3j (IC₅₀?=?0.11 μM, IC₅₀?=?0.18 μM), 3o (IC₅₀?=?0.98 μM, IC₅₀?=?2.76 μM) showed excellent inhibitory activity than the standard Etoposide (IC₅₀?=?2.11 μM, IC₅₀?=?3.08 μM) against MCF-7 and A-549 cell lines, respectively. Docking analysis of all the compounds with the human topoisomerase II revealed that the compound 3j fitted well in the active site pocket, showing the best docking score of 158.072 kcal/mol.

     

A new (E,E)-dioxime and its mono and heterotrinuclear complexes containing an 18-membered dithiatetraazamacrocycle

The novel (E,E)-dioxime, 5,6:ll,12:17,18-tribenzo-2,3-bis(hydroxyimino)-7,16-dithia-9, 14-dioxo-l,4,10,13-tetraazacyclooctadecane (H₂L) has been synthesized by reacting (E,E)-dichloroglyoxime (2) with 2,3:8,9:14,15-tribenzo-4,13-di-thia-6,11-dioxa-l,7,10,16-tetraazahexzadecane (3), prepared by the reaction of N,N-bis(chloroacetyl)-1, 2-phenylene-diamine (1) with 2-aminothiophenol. Mononuclear complexes (4, 5) of this ligand have been synthesized by reacting the vic-dioxime (H₂L) with K₂PtCl₄ and NiCl₂ · 6H₂O, respectively. Heterotrinuclear complexes (6)and(7) have been prepared by the reaction of (4) and (5) mononuclear complexes with [Cu(MeCN)₄]PF₆. The structures of the vic-dioxime and its mono and trinuclear complexes were identified by elemental analysis, ¹H- and ¹³C-n.m.r, i.r. and m.s. data.