Two new macrocyclic Schiff bases (II) and (III) containing nitrogen ‐ oxygen donor atoms were synthesized by reaction between diethylene triamine or 2,2′‐(ethylenedioxy)bis(ethylamine) and the intermediate compound: 1,4‐bis(6‐methoxy‐2‐formylphenyl)‐1,4‐dioxabutane (I). Identification of these macrocyclic Schiff bases: 1,12, 15,18, 29,32 ‐ hexaaza ‐ [3,4;8,9;20,21;26,27‐tetra‐(6′‐methoxyphenyl)]‐5,8,22,25‐tetraoxa cyclo tetratriacosine‐1,11,18,28‐tetraene. (II) 1,12,21,32‐tetraaza‐[3,4;9,10;23,24;29, 30‐tetra‐(6′‐methoxyphenyl)]‐5,8,15,18,25,28,35,38‐octaoxa cyclo ‐ tetracontane‐1,11,21,31‐tetraene. (III) were determined by elemental analysis (LC‐MS), (IR) and (1H and 13C‐NMR) spectroscopy. The liquid‐liquid extraction of metal picrates such as Ag+ and Cu2+ from aqueous phase to organic phase was carried out using these ligands. The effect of chloroform and dichloromethane as organic solvents over the metal picrate extractions were investigated at 25 ± 0.1 °C by using atomic absorption spectrometer. 相似文献
3-Nitro-N-(phenylsulphonyloxy)phthalimide (IIIa) and N-(phenylsulphonyloxy)phthalimide (IIIb) were synthesised as key intermediates in good yield. Their structures were confirmed by 1H NMR and FTIR spectral data. The reaction of the key intermediates with allylamine produced 3-allyl-5-nitroquinazoline-2,4-(1H,3H)-dione (IVa) and 3-allylquinazoline-2,4-(1H,3H)-dione (IVb), respectively. Luminescence emission and excitation spectra of IVa and IVb are also presented. 相似文献
This paper introduces the concept of quadratic-mean pseudo almost periodicity and gives some fundamental properties. In particular, it establishes a composition theorem of this kind of functions. As an application, and by virtue of the theory of the semi-groups of the operators, the Banach fixed point theorem and the stochastic analysis techniques, this paper investigates the existence of the quadratic-mean pseudo almost periodic solutions for a general class of delayed stochastic evolution equations in a Hilbert space. 相似文献
Shunting Inhibitory Artificial Neural Networks are biologically inspired networks in which the synaptic interactions are mediated via a nonlinear mechanism called shunting inhibition, which allows neurons to operate as adaptive nonlinear filters. This paper considers the problem of existence and exponential stability of the pseudo almost periodic solution for shunting inhibitory cellular neural networks with mixed delays. The Banach fixed point theorem and the variant of a certain integral inequality with explicit estimate are used to establish the results. The results of this paper are new and they complement previously known results. 相似文献
A fluorogenic derivatization method for the determination of chlorpropamide in human serum was developed by means of high-performance liquid chromatography (HPLC) with fluorescence detection. The Suzuki coupling reaction with a non-fluorescent reagent, phenylboronic acid (PBA), was employed to convert chlorpropamide into highly fluorescent biphenyl derivative. Chlorpropamide was extracted from human serum by liquid–liquid extraction with toluene after addition of hydrochloric acid, and subsequently reacted with PBA. Because the fluorogenic derivatization was highly selective for aryl halide, the proposed method allowed sensitive and selective detection of chlorpropamide with a detection limit (at a signal to noise ratio of 3) of 0.5 ng mL−1. The sensitivity of our method was from 4 to 100 times better than HPLC–UV, gas chromatography, and LC-mass spectrometry.
A fluorogenic derivatization method for the determination of chlorpropamide in human serum was developed by means of high-performance liquid chromatography (HPLC) with fluorescence detection. The Suzuki coupling reaction with a non-fluorescent reagent, phenylboronic acid (PBA), was employed to convert chlorpropamide into highly fluorescent biphenyl derivative. Chlorpropamide was extracted from human serum by liquid–liquid extraction with toluene after addition of hydrochloric acid, and subsequently reacted with PBA. Because the fluorogenic derivatization was highly selective for aryl halide, the proposed method allowed sensitive and selective detection of chlorpropamide with a detection limit (at a signal to noise ratio of 3) of 0.5 ng mL?1. The sensitivity of our method was from 4 to 100 times better than HPLC–UV, gas chromatography, and LC-mass spectrometry. 相似文献
The present study reports a simple method to control the mechanical and surface properties of cellulose fiber networks and to protect them from humidity, without altering their initial morphology. This is achieved by dip coating the fiber networks in solutions containing different amounts of ethyl cyanoacrylate monomer (ECA). Under ambient humidity and due to the presence of the -OH groups of the cellulose, the ECA polymerizes around each individual cellulosic fiber forming a thin poly(ethyl cyanoacrylate) (PECA) shell. PECA was found to interact with the cellulose surface via hydrogen bonding as evidenced by Fourier transform infrared spectroscopy and thermogravimetric analysis measurements. The detailed surface characterization reveals that only 3.5 wt% of ECA in solution is sufficient to form compact PECA cladding around every cellulose fiber. After the proposed treatment the cellulose sheets become hydrophobic, well protected from the environmental humidity and with increased Young’s modulus. 相似文献
Preparation of radioidinated L-α-methyl tyrosine by the oxidative radioiodination using chloramine-T (CAT) and iodogen (1,3,4,6-tetrachloro,-3α,
6α-diphenyl glycoluril) to generate electrophilic radioiodine has been carried out. The factors affecting the labeling yield
such as pH of the medium, reaction time, substrate and oxidizing agent concentrations have been investigated to optimize the
conditions for the preparation of radioiodinated L-α-methyl tyrosine in high radiochemical yields. Side product impurities
were observed at long reaction times and high oxidizing agent concentrations. Maximum radiochemical yields of 89.7±1.5% and
87.8±1.6% were obtained in case of CAT and iodogen, respectively. Separation and purification by high pressure liquid chromatography
(HPLC) resulted in radiochemically pure products. Using high specific activity123I, the SPECT brain imaging agent can be prepared. 相似文献
Two new atropisomeric electron-poor chiral diphosphine ligand analogues of SYNPHOS were prepared, and their electronic properties are described. These two ligands afforded high performance for the Rh-catalyzed asymmetric 1,4-addition of arylboronic acids to α,β-unsaturated carbonyl compounds at room temperature. 相似文献