Two non-linear azide containing heteronuclear complexes: crystal structure and thermal decomposition

Bis-N,N′(salicylidene)-2,2′-dimethyl-1,3-propanediamine (LDMH₂) has a high tendency to form polynuclear complexes. Two trinuclear complexes were obtained using this ligand and azide ions; (CuLDM)₂ · Mn(N₃)₂ · (DMF)₂, [(C₁₉H₂₀N₂O₂Cu)₂ · Mn(N₃)₂ · (C₃H₇NO)₂] and (CuLDM)₂ · Cd(N₃)₂ · (DMF)₂, [(C₁₉H₂₀N₂O₂Cu)₂ · Cd(N₃)₂ · (C₃H₇NO)₂]. The structures were identified with X-ray methods. TG and DSC methods were also employed to these complexes. Studies showed the (CuLDM)₂ · Mn(N₃)₂ · (DMF)₂ and (CuLDM)₂ · Cd(N₃)₂ · (DMF)₂ to be non-linear. Also μ-bridges were not encountered for the azide ions but were seen to form between the Cu and other metal via phenolic oxygens. Thermal analysis showed exothermic degradation of the azide ions destroying the trinuclear structure. Although azide containing structures show explosive characteristics, this was not observed for the present compounds.     

A facile synthesis of novel 1,4-benzoxazepin-2-one derivatives

An efficient and simple synthesis of 1,4-benzoxazepin-2-one derivatives has been achieved via the reaction of isoquinoline, activated acetylenes, and 1-(6-hydroxy-2-isopropenyl-1-benzofuran-yl)-1-ethanone in water without using any catalyst. This one-pot reaction occurs in high yields under mild conditions.     

New Nitrogen Derivatives of Podophyllotoxin and a Novel Access to Dehydroanhydropicropodophyllin

The new compounds podophyllotoxone oxime (3) and epipodophyllotoxin azide (5) were prepared. The known dehydroanhydropicropodophyllin (6) was unexpectedly obtained from podophyllotoxin (1) by treatment with TMSCl/NaI/MeCN.     

Aldehyde Intermediates in the Synthesis of Tacamine-Type Indole Alkaloids: Preparation of (±)-apotacamine

The synthesis of aldehyde intermediates suitable for the preparation of indole alkaloids of the tacamine ( 1 ) type is described. The four possible aldehydes 4–7 were prepared from methyl 5-ethylnicotinate ( 8 ) in a few simple steps using a base-catalyzed epimerization as the final step (Schemes 1 and 2). The key aldehyde 4 , which is an analogue of the important vincamine intermediate 3 (‘Oppolzer's aldehyde’), was finally converted into the indole alkaloid (±)-apotacamine ( 21 ).     

The Color Reaction of Mercury(II) with the New Reagent 2-Methylthiophenyldiazoaminoazobenzene and Its Application

A new and very sensitive and selective chromogenic reagent, 2-methylthiophenyldiazoaminoa-zobenzene (MTDAA), was synthesized and studied in detail for the determination of trace mercury(II) in water samples. The method is based on the color reaction between MTDAA and mercury(II). It was found that mercury(II) reacts with MTDAA in Na₂B₄O₇-NaOH buffer solution (pH = 10.0) to form 1 : 2 red complexes; these show maximum absorption at 520 nm. Beer’s law is obeyed in 0–15 µg of mercury(II) in 25 mL of solution. The apparent molar absorptivity of the complex is 1.33 × 10⁵ L/(mol cm); its limit of quantification, limit of detection, and relative standard deviation are 0.75 ng/mL, 0.27 ng/mL, and 1.0%, respectively, giving better sensitivity. The influence of the reaction variables and the effect of interfering ions are reported; most of the metal ions in water samples can be tolerated in considerable amounts. Only a few ions can interfere with the determination of trace mercury(II), but these can be eliminated by prior extraction. The proposed method is sensitive, simple, and rapid. It has been applied to the determination of trace mercury(II) in water samples with satisfactory results.__________From Zhurnal Analiticheskoi Khimii, Vol. 60, No. 7, 2005, pp. 703–706.Original English Text Copyright © 2005 by Guo, Din, Tian, Liu, Chang, Meng.The text was submitted by the authors in English.     

Direct determination of sulfite in food samples by a biosensor based on plant tissue homogenate

In the work described here, a biosensor was developed for the determination of sulfite in food. Malva vulgaris tissue homogenate containing sulfite oxidase enzyme was used as the biological material. M. vulgaris tissue homogenate was crosslinked with gelatin using glutaraldehyde and fixed on a pretreated Teflon membrane. Sulfite was enzymatically converted to sulfate in the presence of the dissolved oxygen, which was monitored amperometrically. Sulfite determination was carried out by standard curves, which were obtained by the measurement of consumed oxygen level related to sulfite concentration. Several operational parameters had been investigated: the amounts of plant tissue homogenate and gelatin, percentage of glutaraldehyde, optimum pH and temperature. Also, some characterization studies were done. There was linearity in the range between 0.2 and 1.8 mM at 35 °C and pH 7.5. The results of real sample analysis obtained with the biosensor agreed well with the enzymatic reference method using spectrophotometric detection.     

Synthesis,Characterization, and Magnetic Behavior of Cobalt-Ferrite Nanoparticles under Variant Temperature Conditions

Physics of the Solid State - Wet chemical method was applied for the synthesis of cobalt-ferrite nanoparticles. The physicochemical properties were investigated by number of analytical techniques....