Development of a Novel Automatic Potentiometric System for Determination of Selenium and Its Application in Pharmaceutical Formulations and Anodic Slime

Poly(vinyl chloride) polymeric membrane sensors containing Sn(IV) phthalocyanine dichloride (SnPC) and Co(II) phthalocyanine (CoPC) as novel electroactive materials dispersed in o‐nitrophenyl octylether (o‐NPOE) as a plasticizer are examined potentiometrically with respect to their response toward selenite (SeO₃^2?) ions. Fast Nernstian response for SeO₃^2? ions over the concentration ranges 7.0×10^?6–1.0×10^?3 and 8.0×10^?6–1.0×10^?3 mol L^?l at pH 3.5–8.5 with lower detection limit of 5.0×10^?6 and 8.0×10^?6 mol L^?1 and calibration slopes of ?25.4 and ?29.7 mV decade^?1 are obtained with SnPC and CoPC based membrane sensors, respectively. The proposed sensors reveals by the modified separate solution method (MSSM) a good selectivity over different anions which differ significantly from the classical Hofmeister series. A segmented sandwich membrane method is used to determine complex formation constants of the ionophores in situe in the solvent polymeric sensing membranes. Membrane incorporating CoPC in a tubular flow detector is used in a two channels flow injection set up for continuous monitoring of selenite at a frequency of ca. 50 samples h^?1. Direct determination of selenium in pharmaceutical formulations and anodic slime gives results in good agreement with data obtained using standard ICP method.     

Mechanism of [M+H]+ formation in atmospheric pressure photoionization mass spectrometry: Identification of propionitrile in acetonitrile with high mass accuracy measurement and tandem mass spectrometry and evidence for its involvement in the protonation phenomenon

The role of propionitrile in the production of [M+H]+ under atmospheric pressure photoionization (APPI) was investigated. In dopant-assisted APPI using acetone and anisole, protonated acetone and anisole radical cations were the most prominent ions observed. In dopant-free or direct APPI in acetonitrile, however, a major ion in acetonitrile was detected and identified as propionitrile, using high accuracy mass measurement and collision induced dissociation studies. Vaporizing ca. 10(-5) M althiazide and bendroflumethazide under direct APPI in acetonitrile produced their corresponding protonated species [M+H]+. In addition to protonated acetonitrile, its dimers, and acetonitrile/water clusters, protonated propionitrile, propionitrile dimer, and propionitrile/water clusters were also observed. The role of propionitrile, an impurity in acetonitrile and/or a possible product of ion-molecule reaction, in the production of [M+H]+ of althiazide and bendroflumethazide was further investigated in the absence of dopant using propionitrile-d5. The formation of [M+D]+ species was observed, suggesting a possible role of propionitrile in the protonation process. Additionally, an increase in the [M+H]+ signal of althiazide and bendroflumethazide was observed as a function of propionitrile concentration in acetonitrile. Theoretical data from the literature supported the assumption that one possible mechanism, among others, for the formation of [M+H]+ could be attributed to photo-initiated isomerization of propionitrile. The most stable isomers of propionitrile, based on their calculated ionization energy (IE) and relative energy (DeltaE), were assumed to undergo proton transfer to the analytes, and mechanisms were proposed.     

Variability of two essential oils of Kundmannia sicula (L.) DC., a traditional Algerian medicinal plant

The essential oils of the aerial parts of Kundmannia sicula (L.) DC collected from two Algerian localities, El Kala (near the coast) and Béjaia (from a meadow about 10 km from the coast), were analysed by GC and GC-MS. Although both samples showed similar overall chemical compositions, the major components of the Béjaia sample were identified as being spathulenol (14.8%), caryophyllene oxide (12.2%), salvial-4(14)en-1-one (10.1%), 1,5-epoxysalvial-4(14)ene (5.2%) and germacrene D (3.2%), while in the ElKala sample the main compounds were found to be salvial-4(14)en-1-one (16.4%), 1,5-epoxysalvial-4(14)ene (6.5%), chrysanthenyl acetate (5.2%) and alpha-amorphene (2.9%).     

Application of Multilinear Gradient Elution for Optimization of Separation of Chlorophenols Using Derringer’s Desirability Function

Multilinear gradient elution was applied for the simultaneous optimization of resolution and analysis times of nine chlorophenols separated by HPLC. The first relationship of ln k versus φ was determined using the isocratic retention time for each analyte. For prediction of gradient retention times of analytes, the fundamental equation of gradient elution was numerically solved. Then a grid search program was used to simulate chromatograms under each new condition. Two different chromatographic goals, analysis time and minimum distance between adjacent peaks, were evaluated simultaneously using Derringer’s desirability function for each chromatogram. The sigmoid function was used to transform the optimization criteria to desirability values. Under optimal conditions, a good agreement was observed between predicted and experimental values of the chromatographic response function when analysis time was less than 40 min.     

Structure-based design and synthesis of acyclic and substituted heterocyclic phosphonates linearly linked to thiazolobenzimidazoles as potent hydrophilic antineoplastic agents

As a contribution to our investigations to develop multidisciplinary entities of substituted heterocycle phosphor esters, in this paper, we prepared a series of thiazolobenzimidazoles incorporating phosphor esters of potential anticancer properties. Phosphoryl reagents were applied on E-3-(N,N-dimethylamino)-1-(3-methythiazolo[3,2-a]benzoimidazol-2-yl)prop-2-en-1-one and 1-(3-methylthiazolo[3,2-a]benzimidazol-2-yl)ethanone. The reactions proceeded under mild conditions to give an ensemble of 14 new phosphonates in good yields (68–74%). The stereoselective chemistry was studied by a series of heteronuclear ¹³C[¹H]-nOe experiments. Based on the prediction studies in the early stage using PASS algorithm 14, the synthesized phosphonates were evaluated as antitumor candidates at a dose of 10 µmol/mL against human breast and human colon tumor (4 cultured cell lines each). Three products showed significant antineoplastic potency in relative to the standard drug, adriamycin. Permeability of the lead molecules was determined and the structure–activity relationship (SAR) was discussed to suggest a pro-drug chromophore. Furthermore, there was good coincidence of experimental data of antitumor properties and prediction results.     

The anodic reactivity of 4,4′-dimethoxychalcone: a synthetic and mechanistic investigation

The anodic oxidation of the 4,4′-dimethoxychalcone (DMC) was investigated by different electrochemical methods at a platinum working electrode and in acetonitrile as a solvent. The DMC exhibited a single irreversible anodic peak around 1.6 V versus Ag/AgCl. On the time scale of cyclic voltammetry experiments, the highly reactive radical cation issued from the first electron transfer underwent a second order rate-limiting reaction. The potential imposed electrolyses of DMC led to the formation of a semi-conducting oligomer with 40 % yield. Using different physico-chemicals methods, the structural study confirmed the formation of an o-phenylenevinylene oligomer. The values of the corresponding optical and electrochemical band gaps were calculated to be 3.15 and 2.86 eV, respectively. Finally, a mechanism for the DMC electro-oligomerization was proposed on the basis of the obtained results.     

Prediction of Mass Spectral Response Factors from Predicted Chemometric Data for Druglike Molecules

A method is developed for the prediction of mass spectral ion counts of drug-like molecules using in silico calculated chemometric data. Various chemometric data, including polar and molecular surface areas, aqueous solvation free energies, and gas-phase and aqueous proton affinities were computed, and a statistically significant relationship between measured mass spectral ion counts and the combination of aqueous proton affinity and total molecular surface area was identified. In particular, through multilinear regression of ion counts on predicted chemometric data, we find that log₁₀(MS ion counts) = –4.824 + c ₁?PA + c ₂?SA, where PA is the aqueous proton affinity of the molecule computed at the SMD(aq)/M06-L/MIDI!//M06-L/MIDI! level of electronic structure theory, SA is the total surface area of the molecule in its conjugate base form, and c ₁ and c ₂ have values of –3.912 × 10^–2 mol kcal^–1 and 3.682 × 10^–3 Å^–2. On a 66-molecule training set, this regression exhibits a multiple R value of 0.791 with p values for the intercept, c ₁, and c ₂ of 1.4 × 10^–3, 4.3 × 10^–10, and 2.5 × 10^–6, respectively. Application of this regression to an 11-molecule test set provides a good correlation of prediction with experiment (R = 0.905) albeit with a systematic underestimation of about 0.2 log units. This method may prove useful for semiquantitative analysis of drug metabolites for which MS response factors or authentic standards are not readily available.

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Simple two-dimensional model for the elastic origin of cooperativity among spin states of spin-crossover complexes

We study the origin of the cooperative nature of spin crossover (SC) between low-spin and high-spin (HS) states from the viewpoint of elastic interactions among molecules. As the size of each molecule changes depending on its spin state, the elastic interaction among the lattice distortions provides the cooperative interaction of the spin states. We develop a simple model of SC with intra and intermolecular potentials which accounts for the elastic interaction including the effect of the inhomogeneity of the spin states and apply constant temperature molecular dynamics based on the Nosé-Hoover formalism. We demonstrate that, with increase of the strength of the intermolecular interactions, the temperature dependence of the HS component changes from a gradual crossover to a first-order transition.     

One-pot green synthesis,study of fluorescence properties,and biological activity of pyrano[3,2-c]chromenes derivatives via mesoporous materials MgO/SBA-15

This current work describes the preparation of MgO-SBA-15 catalysts by ultrasonic method, and it is characterized by the different analysis techniques of XRD, BET, SEM, and IRTF. In order to find out an application for this mesoporous material, MgO/SBA-15 was used as a heterogeneous catalyst in the one-pot synthesis of pyrano[3,2-c]chromenes derivatives isolated at room temperature reaction according to green chemistry criteria. To enhance these derivatives, a spectroscopic study of molecular fluorescence properties was carried out as well as an identification analysis by nuclear magnetic resonance and FTIR was used. Furthermore, biological activity experiment is also carried out, from where the obtained test results were satisfactory for AC09 , AC05 , and AC10 compounds and they are checked after computation by molecular modeling.