新型磺酸功能化吡啶盐酸盐离子液体催化剂用于六氢喹啉合成(英文)

Sulfonic acid functionalized pyridinium chloride [pyridine-SO3 H]Cl has been synthesized as a novel Brnsted acidic ionic liquid and characterized on the basis of its FT-IR,1H and 13C NMR,MS,ther-mogravimetry,and derivative thermogravimetry data.The material has also been used as a highly efficient,homogeneous,and reusable catalyst for the preparation of hexahydroquinolines according to the one-pot multi-component condensation of arylaldehydes,dimedone(5,5-dimethylcyclohexane-1,3-dione),β-ketoesters,and ammonium acetate under solvent-free conditions.     

Silver nanoparticle loaded on activated carbon and activated carbon modified with 2-(4-isopropylbenzylideneamino)thiophenol (IPBATP) as new sorbents for trace metal ions enrichment

The efficiencies and performances of silver nanoparticle loaded activated carbon modified with 2-(4-isopropylbenzylideneamino)thiophenol (IPBATP-Ag-NP-AC) and activated carbon modified with IPBATP (IPBATP-AC), as new sorbents, were evaluated for separation and preconcentration of Cu²⁺, Zn²⁺, Co²⁺, Cd²⁺ and Pb²⁺ ions from real environmental samples. The retained metals content was reversibly eluted using 5?mL of CH₃COOH (6.0?mol?L^?1) and/or 10?mL of 4.0?mol?L^?1 HNO₃ for IPBATP-Ag-NP-AC and IPBATP-AC, respectively. The experimental parameters influence the recoveries of metal ions including pH, amounts of ligand and supports, condition of eluents, sample and eluent flow rates of has been investigated. The preconcentration factors were found to be 100 for Zn²⁺, Cd²⁺, Co²⁺, Cu²⁺ and 50 for Pb²⁺ ions using IPBATP-Ag-NP-AC, and 50 for Zn²⁺, Cd²⁺, Co²⁺, Cu²⁺ and 25 for Pb²⁺ ions using IPBATP-AC. The detection limit of both SPE-based sorbents was between 1.6–2.5?ng?mL^?1 for IPBATP-AC and 1.3–2.5?ng?mL^?1 for IPBATP-Ag-NP-AC. The proposed methods have been successfully applied for the extraction and determination of the understudy metal ions content in some real samples with extraction efficiencies higher than 90% and relative standard deviations (RSD) lower than 2.4%.     

Ab initio study of NH3 and H2O adsorption on pristine and Na-doped MgO nanotubes

We have investigated, on the basis of density functional theory calculations, the structural and electronic properties of chemical modification of pristine and Na-doped MgONTs with NH₃ and H₂O molecules. We found that the NH₃ and H₂O molecules can be barrierlessly adsorbed on the Mg atom of the tube sidewall along with a charge transfer from the adsorbate to MgONT. The adsorption is chemical in nature with adsorption energies about ?22.3 and ?21.5 kcal/mol for H₂O and NH₃, respectively. The calculated density of state (DOS) shows that the chemical modification of MgONTs with these molecules can be generally classified as certain type of “harmless modification.” In other words, the electronic properties of the MgONT are little changed by the adsorption processes. The substitution of an Mg atom in the tube surface with an Na atom results in a semi-insulator to p-type semiconductor transition based on DOS analysis. It was also found that the doping process reduces the adsorption energies and the electronic properties of Na-doped MgONT is slightly more sensitive toward NH₃ and H₂O molecules, compared with the pristine one.     

Synthesis,characterization, thermal,electrochemical, and DFT studies of mononuclear cyclopalladated complexes containing bidentate phosphine ligands and their biological evaluation as antioxidant and antibacterial agents

The non-symmetric phosphorus ylides and their Pd(II) complexes have been synthesized as potential antioxidant and antibacterial compounds and their structures were elucidated using a variety of physicochemical techniques. The reaction of 1 equiv non-symmetric phosphorus ylides, Ph₂PCH₂PPh₂C(H)C(O)PhX (X = Br (Y¹), Cl (Y²), NO₂ (Y³), OCH₃ (Y⁴)) with [Pd(dppe)Cl₂] (M¹), followed by treatment with 2 equiv AgOTf led to monomeric chelate complexes, [(dppe)Pd(Ph₂PCH₂PPh₂C(H)C(O)PhX)] (OSO₂CF₃)₂ (X = Br (C¹), Cl (C²), NO₂ (C³), OCH₃ (C⁴)), which contain a five-membered P,P chelate ring in one side and a five-membered P,C chelate ring in the other side. Palladium ion complexes were synthesized and investigated by cyclic voltammetry, FT-IR, UV–visible, multinuclear (¹H, ³¹P and ¹⁹F) NMR, thermal analysis and ESI-mass spectroscopic studies. Some complexes and ligands have been studied by powder XRD and single crystal X-ray diffraction techniques. FT-IR and ³¹P NMR studies revealed that the ylides Y are coordinated to the metal ions via the terminal phosphorus (P_c) of the ylides and methene group (CH). The proposed coordination geometry around the Pd atom in these complexes is defined as slightly distorted square planar by UV-Visible and DFT studies. Thermal stability of all complexes was also shown by TG/DTG methods. Furthermore, the electrochemical behavior of the complexes was investigated by cyclic voltammetry. The results indicate that all complexes are successfully synthesized from the initial ligands. All complexes were analyzed for their antioxidant properties by DPPH free radical scavenging assay. In addition, the antibacterial effects of the hexane-solved complexes were investigated by disc diffusion method against four Gram positive and negative bacteria. All complexes represented antibacterial activity against bacteria tested especially on Gram positive ones. A theoretical study on the structure, ¹H and ³¹P NMR chemical shifts and the interaction energy between the Pd²⁺ ion and ligands dppe and ylide Y is also reported.     

Synthesis of 4-(1,3-dioxo-2,3-dihydro-1H-2-indenyl) substituted 1-benzylpyrrole-3-carboxylates via a tandem four-component reaction

An efficient approach for the preparation of functionalized 4-(1,3-dioxo-2,3-dihydro-1H-2-indenyl) substituted 1-benzylpyrrole-3-carboxylates is described. This four-component reaction between ninhydrin, 1-phenyl-2-(1,1,1-triphenyl-λ⁵-phosphanylidene)-1-ethanone, primary amines and alkyl acetoacetate proceeds in MeOH under reflux condition in good to excellent yields.     

A one-pot synthesis of 5,5-disubstituted hydantoin derivatives using magnetic Fe3O4 nanoparticles as a reusable heterogeneous catalyst

A facile and rapid method for the one-pot synthesis of 5,5-disubstituted hydantoins in the presence of magnetic Fe₃O₄ nanoparticles has been developed. The multicomponent reactions of carbonyl compounds (aldehydes and ketones), potassium cyanide and ammonium carbonate were carried out under solvent-free conditions to obtain various hydantoin derivatives. The magnetic catalyst could be readily separated by an external magnet from the reaction mixture. This procedure has many advantages, such as the use of a reusable magnetic catalyst, high yields, short reaction times, simplicity and very easiness with implementing the methodology.     

Complexation studies of Mn2+, Zn2+ and Cd2+ ions with a series of tetradentate (N4) Schiff base ligands containing pyridine moiety in acetonitrile and nitromethane solutions by a competitive NMR technique using 7Li nucleus as a probe

Lithium-7 NMR spectroscopy was used to investigate the stoichiometry and stability of a Li⁺ complex with N¹,N²-bis(pyridin-2-ylmethylene)ethane-1,2-diamine (L¹), N¹,N³-bis(pyridin-2-ylmethylene)propane-1,3-diamine (L²) and N¹,N⁴-bis(pyridin-2-ylmethylene) butane-1,4-diamine (L³) in acetonitrile (AN) and nitromethane (NM) solutions. A competitive ⁷Li NMR method was also employed to probe the complexation of Mn²⁺, Cd²⁺ and Zn²⁺ ions with L¹, L² and L³ in the same solvents. The formation constants of the resulting complexes were evaluated from computer fitting of the mole ratio data to an equation that relates the observed chemical shifts to the formation constant. In both solvents, the stability of the resulting 1:1 complexes were found to vary in the order Zn²⁺>Cd²⁺>Mn²⁺>Li⁺. In addition, the stability of M–L complexes of M²⁺ with the Schiff base ligands found to vary in the order M²⁺–L¹ > M²⁺–L² > M²⁺–L³.     

Reactions of 6‐Aminouracils: The First Simple,Fast, and Highly Efficient Synthesis of bis(6‐Aminopyrimidonyl)methanes (BAPMs) Using Thermal or Microwave‐Assisted Solvent‐Free Methods

A detailed study on the condensation reaction of 6‐aminouracils and aldehydes has been investigated, and accordingly we established for the first time two green, fast, and highly efficient methods for the preparation of bis(6‐aminopyrimidonyl)methanes (BAPMs).     

The trigonometric tables of al-Kāshī in his Zīj-i Khāqānī

The trigonometric tables of al-Kāshī in his Zīj-i Khāqānī are described and the degree of their accuracy is investigated. Also, his account of the particular interpolation schemes based on the numerical material of the tables is translated into English and given with a commentary.