Highly Selective One-Pot Coupling Reaction of Indole,Aromatic Aldehydes,and 4-hydroxycoumarin Using Copper Octoate as a Homogeneous Catalyst

A facile protocol for the one-pot, multicomponent reaction of indole, 4-hydroxycoumarin, and aromatic aldehydes was developed using copper octoate as an inexpensive, commercially available, and efficient catalyst. This highly selective reaction eliminates the formation of homodimeric by-products (bisindoles and biscoumarins) and selectively results in the formation of heterodimeric adducts containing both indole and coumarin heterocycles.     

Pyrophosphate Selective Recognition in Aqueous Solution Based on Fluorescence Enhancement of a New Aluminium Complex

A novel and simple fluorescence enhancement method for selective pyrophosphate(PPi) sensing was proposed based on a 1:1 metal complex formation between bis(8-hydroxy quinoline-5-solphonat) chloride aluminum(III) (Al(QS)₂Cl), (L) and PPi in aqueous solution. The linear response range covers a concentration range of 1.6 × 10⁻⁷ to 1.0 × 10⁻⁵ mol/L of PPi and the detection limit of 2.3 × 10⁻⁸ mol/L. The association constant of L-PPi complex was calculated 2.6 × 10⁵ L/mol. L was found to show selectively and sensitively fluorescence enhancement toward PPi over than I₃^-, NO₃^-, CN⁻, CO₃²⁻, Br⁻, Cl⁻, F⁻, H₂PO4⁻ and SO₄²⁻, which was attributed to higher stability of inorganic complex between pyrophosphate and L.     

Sm3+ Potentiometric Membrane Sensor as a Probe for Determination of Some Pharmaceutics

The increase use of ion sensors in the fields of environmental, agricultural, and medical analysis is stimulating analytical chemists to develop new sensors for fast, accurate, reproducible, and selective determination of various ions. In this study a new samarium membrane sensor was constructed and for the first time, it was applied as a probe in indirect determination of hyoscine, homatropine, and tramadol drugs in their pharmaceutical formulation. The proposed membrane sensor was constructed based on a membrane containing 2% sodium tetraphenyl borate (NaTPB) as an anionic additive, 63% dibutyl phthalate (DBP) as solvent mediator, 5% ionophore, and 30% poly(vinyl chloride) (PVC). The proposed Sm(III) electrode exhibits a Nernstian response of 19.35±0.2 mV per decade of samarium concentration, and has a lower detection limit of 1.0×10^?7 M. The linear range of the sensors was 1.0×10^?7–1.0×10^?1 M. It works well in the pH range of 3.0–8.0.     

New Re(I) tricarbonyl-diimine complexes with N,N′-bis(substituted benzaldehyde)-1,2-diiminoethane Schiff base ligands: Synthesis,spectroscopic and electrochemical studies and crystal structures

The syntheses, structures and spectroscopic properties of tricarbonylrhenium(I) complexes with N,N′-bis(2-bromo, 4-bromo, 4-chloro and 3-methoxybenzaldehyde)-1,2-diiminoethane Schiff base ligands have been investigated in this paper. Characterization of these complexes was carried out with FTIR, NMR, UV–Vis spectroscopy, elemental analysis and X-ray crystallography. The electrochemical behavior of the investigated complexes has been studied by cyclic voltammetry. The crystal structures of the 4-chloro, 4-bromo and 4-methoxy substituted complexes are stabilized by intermolecular C–H?Cl and C–H?O hydrogen bonds. The remarkable features of the 2-bromo, 4-bromo and 4-chloro substituted complexes are short intermolecular halogen–oxygen contacts. In the 4-bromo complex, short intermolecular Br?O and O?O contacts link neighboring molecules along the [1 0 0] direction, which are further stabilized by short intermolecular π?π interactions. In 2-bromo complex, intermolecular Br?O interactions link neighboring molecules into 1D extended chains along the [0 1 0] and [0 0 1] directions, forming a 2D network which is parallel to the bc-plane.     

Synthesis and characterization of copper(II) complexes incorporating pyrazolyl-derived N,S-donor bidentate ligands

The novel bidentate N,S-donor anionic ligands [PhNCSIndz]^?, [PhNCSImz]^?, [PhNCSPz^Me3]^?, and [EtNCSPz]^?, where Indz?=?indazole, Imz?=?imidazole, Pz^Me3?=?3,4,5-trimethylpyrazole, and Pz?=?pyrazole, were synthesized and used to prepare Cu(II) complexes of general formula [Cu(N^S)₂]. The ligands were synthesized via direct addition of phenylisothiocyanate or ethylisothiocyanate into THF suspensions of the corresponding sodium-pyrazolate salts. All of the synthesized compounds, including the ligands and the complexes, were characterized by physico-chemical and spectroscopic methods, and crystal structures of [Cu(EtNCSPz)₂] and [Cu(PhNCSPz^Me2)₂] were determined by X-ray diffraction analysis, showing a trans-square planar geometry for [Cu(EtNCSPz)₂] and a distorted tetrahedral geometry for [Cu(PhNCSPz^Me2)₂].     

{Δ‐1,4,7,10‐Tetrakis[(S)‐2‐hydroxy­propyl‐κO]‐1,4,7,10‐tetra­aza­cyclo­do­dec­ane‐κ4N}cad­mium(II) 4‐nitrophenolate per­chlor­ate hydrate

Crystallization of [Cd(S‐thpc12)](ClO₄)₂·H₂O {S‐thpc12 is 1,4,7,10‐tetra­kis[(S)‐2‐hy­drox­y­propyl]‐1,4,7,10‐tetra­aza­cy­clo‐do­dec­ane} in the presence of sodium p‐nitrophenolate forms the title complex, [Cd(C₂₀H₄₄N₄O₄)](C₆H₄NO₃)(ClO₄)·H₂O, in which p‐nitrophenolate and water separately hydrogen bond to a different pair of cis‐related pendant hydroxyl groups which, together with the four N atoms, are themselves bound to Cd^II in an approximately square antiprismatic arrangement. The diastereoselectivity of the complex‐forming process is apparent from the fact that both different disymmetric cations in the asymmetric unit have the same Δ helicity.     

Synthesis and structural study of bis-perfluoropyridyl bridged by 1,4 and 1,2 dihydropyridine

Bis-perfluoropyridyl bridged by 1,4 and 1,2 dihydropyridine compounds was synthesized by reaction of 2 and 4 aminopridine derivatives with pentafluoropyridine. The structures were determined by X-ray crystallography. Compound 3a comprises two crystallographically independent molecules in the asymmetric unit in which one of them shows 1-D infinite chains along [0 1 0] direction due to the intermolecular C-H?N hydrogen bonds. In compound 5 intermolecular C-H?F and C-H?N hydrogen bonds link neighbouring molecules to each other. In addition, in both structures a series of C-F?π interactions stabilize the crystal packing.     

A chaotic secure communication scheme using fractional chaotic systems based on an extended fractional Kalman filter

In recent years chaotic secure communication and chaos synchronization have received ever increasing attention. In this paper, for the first time, a fractional chaotic communication method using an extended fractional Kalman filter is presented. The chaotic synchronization is implemented by the EFKF design in the presence of channel additive noise and processing noise. Encoding chaotic communication achieves a satisfactory, typical secure communication scheme. In the proposed system, security is enhanced based on spreading the signal in frequency and encrypting it in time domain. In this paper, the main advantages of using fractional order systems, increasing nonlinearity and spreading the power spectrum are highlighted. To illustrate the effectiveness of the proposed scheme, a numerical example based on the fractional Lorenz dynamical system is presented and the results are compared to the integer Lorenz system.