Tetrakis(4-N,N-dimethylaminobenzene)porphyrinato]manganese(III) acetate as a novel carrier for a selective iodide PVC membrane electrode.

[5,10,15,20-Tetrakis(4-N,N-dimethylaminobenzene)porphyrinato]Mn(III) acetate (MnTDPAc) was applied as an ionophore for an iodide-selective PVC membrane electrode. The influences of the membrane composition, pH of the test solution and foreign ions on the electrode performance were investigated. The sensor exhibited not only excellent selectivity to iodide ion compared to Cl- and lipophilic anions such as ClO4- and salicylate, but also a Nernstian response with a slope of -59.4 +/- 1.2 mV per decade for iodide ions over a wide concentration range from 1.0 x 10(-2) to 7.5 x 10(-6) M at 25 degrees C. The potentiometric response was independent of the pH of the solution in the pH range of 2 - 8. The electrode could be used for at least 2 months without any considerable divergence in the potential. Good selectivity for iodide ion, a very short response time, simple preparation and relatively long-term stability were the silent characteristics of this electrode. It was successfully used as an indicator electrode in the potentiometric titration of iodide ions, and also in the determination of iodide from seawater samples and drug formulations.     

The factorization approximation for the Master Equation

We examine the validity of the application of the Factorization Approximation to derive the Master Equation for a microscopic system coupled to a reservoir. We developed a formal perturbation expansion for the time evolution of the system reduced density matrix. We employed a diagrammatic schemes to produce each term of the perturbation series. The diagrams in the time domain provide a distinct criteria to distinguish the diagrams which survive the Factorization Approximation. The Feynmann-like diagrams in the energy domain, originated from the Resolvent method, are used for execution of diagram summations to estimate their overall contributions. We demonstrated that for a two level atomic system, interacting with a thermal reservoir, the summation over the diagrams which survived the Factorization Approximation, yields the proper time evolution of the system, in agreement with the solution of the Master Equation. The summation of the diagrams which are excluded by applying the Factorization Approximation are characterized by a dimensionless parameter: Γ/ω₀, where ω₀ is the frequency of the transition line, and Γ is the line width. The Factorization Approximation is thus rigorously justified when this expansion parameter is very small.     

Spectrophotometric studies on the complexation equilibria of Ni and Pb with 2-carboxy-2-hydroxy-5'-sulfo-formazylbenzene. Simultaneous determination of trace amounts of Ni and Pb

Spectrophotometric studies have been made to investigate the reaction of Nickel and Lead with 2-carboxy-2'-hydroxy-5'-sulfoformazyl-benzene (zincon) in 50%(v/v) ethanol-water at 25 degrees C and an ionic strength of 0.1 M NaClO4. A complete picture of the complexation equilibria in the pH range (4.2-12.0) for nickel and (1.9-11.5) for lead are presented. Simple, rapid, selective and sensitive methods for the spectro-photometric determination of nickel and lead has been developed based on the color reaction of their complexes with zincon. The methods allow the determination of 4.69 microg mL(-1) of nickel at pH = 6.3 (lambdamax = 665 nm) and 10.3 microg ml(-1) of lead at pH = 5.6 (lambdamax = 610 nm). The apparent molar absorptivities were epsilon = 1.3 x 10(4) L mol(-1) cm(-1) for nickel and epsilon = 0.6 x 10(4) L mol(-1) cm(-1) for lead. The interference of a large number of foreign ions and complexing agents has been studied. Thiosulphate, as masking agent allows the simultaneous determination of nickel and lead in the presence of high concentrations of copper. Ascorbic acid, sodium cyanide and or sodium fluoride provide the elimination of many other interferences. The methods have been applied successfully to the simultaneous determination of nickel and lead in an aluminium and non-ferrous alloy.     

Novel application of quantum chemical investigation in terms of substituent parameters: Statistical comparison of dual and single substituent parameter treatments

The correlation analysis of Mulliken charge (Q_M) calculated by using density functional theory (B3LYP/STO-3G) calculations of 1-(4-azido-5-hydroxymethyl-tetrahydro-selenophen-2-ylmethyl)-5-substituted-1H-pyrimidine-2,4-dione, were done by using mono substituent parameter (Hammett’s model), and dual substituent parameter (Taft’s, Reynolds’, and Swain’s models). The dual substituent parameter correlations of the Q_M data gave no significant improvement over single parameter correlations, the best correlation observed with the Taft’s Model as compared with the Swain’s and Reynolds’ Models, respectively. The correlation analysis of Mulliken charge can be used successfully to demonstrate the existence or absence of the interaction between the oxygen of the carbonyl group and selenium atom.     

Interaction of nickel with 4-(2'-benzothiazolylazo) salicylic acid (BTAS) and simultaneous first-derivative spectrophotometric determination of nickel(II) and iron(III)

The solution properties of nickel complex with 4-(2'-benzo-thiazolylazo) salicylic acid (BTAS) have been studied by zero-order absorption spectrophotometry in 40% (v/v) ethanol at 20 degrees C and an ionic strength of 0.1 mol dm(-3) (KNO(3)). The equilibria that exist in solution were established and the basic characteristics of complexes formed were determined. A new direct spectrophotometric method for the determination of trace amounts of the nickel is proposed based on the formation of the Ni (BTAS) complex at pH 7.0. The absorption maximum, molar absorbtivity, and Sandell's sensitivity of 1:1 (M:L) complex are 525 nm, 0.6 x 10(4) l mol(-1) cm(-1) and 2.824 x 10(-9) microg cm(-2), respectively. The use of first-derivative spectrophotometry eliminates the interference of iron and enables the simultaneous determination of nickel and iron using BTAS. Quantitative determination of Ni(II) and Fe(III) is possible in the range (0.59-7.08) and (2.1-8.4) microg ml(-1), respectively with a relative standard deviation of 0.5%. The proposed method has been successfully applied to the simultaneous spectrophotometric determination of nickel and iron in steel alloys and aluminum alloys.     

Phosphorus Pentachloride (PCl5) Mediated Synthesis of Tetraarylporphyrins

A new synthesis of porphyrins from pyrrole and substituted benzaldehydes is described, with PCl₅ as catalyst. Aromatic aldehydes condense irreversibly with pyrrole in the presence of this catalyst, and aerobic oxidation of porphyrinogen provides functionalized porphyrins in yields of 20–65%.     

Solvent Free Synthesis of Coumarins

An efficient synthesis of 3-substituted coumarins under solventless system is described.     

Synthesis and biological screening of some chromonyl-substituted heterocycles derived from 2(3H)-furanone derivative

A 2(3H)-furanone bearing chromonyl moiety at position-3 was synthesized and utilized for the construction of N-heterocycles such as pyrrolone, N-aminoquinolone, and pyridazinone derivatives. The reactivity of the chromonylfuranone toward some nitrogen nucleophiles such as ammonia, benzylamine, hydrazine, and phenylhydrazine was studied. On the other hand, thiation of the starting chromonylfuranone interestingly provides mono- and di-thiated products. The chemoselectivity of these reactions is discussed. The structures of all products obtained were elucidated from their analytical and spectral data. The antimicrobial activities of selected examples of the synthesized compounds were examined against two strains of bacteria and two fungus strains. Some of them showed promising antimicrobial activities.     

Synthesis and reactions of 4H-3,1-benzoxazin-4-one derivative bearing pyrazolyl moiety as antimicrobial and antioxidant agents

Ring opening of 4-aryl-2-phenyloxazol-5-one 1 with 2-aminobenzoic acid in acetic acid and n-butanol gave compounds 2 and 3, respectively. The 4H-3,1-benzoxazin-4-one derivative 4 was synthesized by refluxing of compound 2 in acetic anhydride. Then it reacted with different nitrogen nucleophiles such as hydrazine hydrate, phenylhydrazine, cyclohexylamine, piperidine, ethylenediamine, ethanolamine, semicarbazide hydrochloride, cyanoacetohydrazide and methyl glycinate hydrochloride to give compounds 5–14 in order to study the behavior of these nucleophilic reagents on the performed ring system. All the structures of the newly prepared compounds were characterized by their IR, ¹H-, 13C-NMR and MS spectral data. Some of the synthesized compounds were screened for their antimicrobial and antioxidant activities. Compound 5 showed remarkable activity upon this screening.