A Facile Strategy for Construction of Sensor for Detection of Ondansetron and Investigation of its Redox Behavior and Thermodynamic Parameters

A sodium dodecylsulfate‐doped polypyrrole (SDS‐PPy) film was elaborated on glassy carbon electrode (GCE) by an electrodeposition method in phosphate buffer solution (pH 2.0) containing pyrrole (Py) and sodium dodecyl sulfate (SDS). SDS‐PPy/GCE was used for the construction of sensor, which showed excellent electrochemical response for the detection of ondansetron (OND) compared to conventional PPy. The application of the square wave (SW), with the adsorptive accumulation, indicates a maximum response at 1.33 V in H₂SO₄ (0.5 M). The influence of experimental parameters on determination of OND is discussed. The adsorptive stripping technique showed to be more sensitive, giving responses twice as big as those of non‐accumulated OND. The substantial improvement of response permits the development of an electroanalytical technique with a linear concentration in the range (1.0–80 μM), low detection (0.09 μM), and quantification limits (0.3 μM), and acceptable relative standard deviations of repeatability (0.59 %), and reproducibility (1.51 %). Consequently, this electrode is promising candidate for an accurate electroanalytical determination of OND in pharmaceutical samples with high sensitivity and selectivity, good accuracy and precision. The electrooxidation of OND at SDS‐PPy/GCE at various temperatures were studied by cyclic voltammetry to evaluate both the kinetic (k_s and E_a) and thermodynamic (ΔG*, ΔH* and ΔS*) parameters.     

Sub-ppt level voltammetric sensor for Hg2+ detection based on nafion stabilized l-cysteine-capped Au@Ag core-shell nanoparticles

Journal of Solid State Electrochemistry - Bimetallic nanoparticles (BMNPs) have received considerable attention due to their distinctive properties when compared to the corresponding monometallic...     

Design and Synthesis of Imidazole and Triazole Pyrazoles as Mycobacterium Tuberculosis CYP121A1 Inhibitors

The emergence of untreatable drug-resistant strains of Mycobacterium tuberculosis is a major public health problem worldwide, and the identification of new efficient treatments is urgently needed. Mycobacterium tuberculosis cytochrome P450 CYP121A1 is a promising drug target for the treatment of tuberculosis owing to its essential role in mycobacterial growth. Using a rational approach, which includes molecular modelling studies, three series of azole pyrazole derivatives were designed through two synthetic pathways. The synthesized compounds were biologically evaluated for their inhibitory activity towards M. tuberculosis and their protein binding affinity (K_D). Series 3 biarylpyrazole imidazole derivatives were the most effective with the isobutyl ( 10 f ) and tert-butyl ( 10 g ) compounds displaying optimal activity (MIC 1.562 μg/mL, K_D 0.22 μM ( 10 f ) and 4.81 μM ( 10 g )). The spectroscopic data showed that all the synthesised compounds produced a type II red shift of the heme Soret band indicating either direct binding to heme iron or (where less extensive Soret shifts are observed) putative indirect binding via an interstitial water molecule. Evaluation of biological and physicochemical properties identified the following as requirements for activity: LogP >4, H-bond acceptors/H-bond donors 4/0, number of rotatable bonds 5–6, molecular volume >340 ų, topological polar surface area <40 Ų.     

Comparative Study of Alkali-Cation-Based (Li+, Na+, K+) Electrolytes in Acetonitrile and Alkylcarbonates

The development of a suitable functional electrolyte is urgently required for fast-charging and high-voltage alkali-ion (Li, Na, K) batteries as well as next-generation hybrids supercapacitors. Many recent works focused on an optimal selection of electrolytes for alkali-ion based systems and their electrochemical performance but the understanding of the fundamental aspect that explains their different behaviour is rare. Herein, we report a comparative study of transport properties for LiPF₆, NaPF₆, KPF₆ in acetonitrile (AN) and a binary mixture of ethylene carbonate (EC), dimethyl carbonate (DMC): (EC/DMC : 1/1, weigh) through conductivities, densities and viscosities measurements in wide temperature domain. By application of the Stokes-Einstein, Nernst-Einstein, and Jones Dole equations, the effective ionic solvated radius of cation (r_eff), the ionic dissociation coefficient (α_D) and structuring Jones Dole's parameters (A, B) for salt are calculated and discussed according to solvent or cation nature as a function of temperature. From the results, we demonstrate that better mobility of potassium can be explained by the nature of the ion-ion and ion-solvent interactions due to its polarizability. In the same time, the predominance of triple ions in the case of K⁺, is a disadvantage at high concentration.     

Effect of the lanthanoid-size on the structure of a series of lanthanoid-anilato 2-D lattices*

Abstract

We report the synthesis and characterization of a series of Ln-based bromoanilato 2-D lattices with dimethyl sulfoxide (DMSO): [Ln₂(C₆O₄Br₂)₃(DMSO)_n]·2DMSO·mH₂O with n = 6 and m = 0 for Ln = La (1), Ce (2), Pr (3), Nd (4), Sm (5), Eu (6) and Gd (7); n = 4 and m = 2 for Ln = Tb (8), Dy (9), Ho (10), Er (11), Tm (12) and Yb (13) (C₆O₄Br₂^2? = 3,6-dibromo-2,5-dihydroxy-1,4-benzoquinone = bromoanilato). The X-ray analysis shows that the largest Ln(III) ions (La-Gd, 1-7) crystallize in the monoclinic P21/n space group (phase I), whereas the smaller Ln(III) ions (Tb–Yb, 8–13) crystallize in the triclinic P-1 space group (phase II). Both phases present a (6,3)-2-D topology but show important differences derived from the different coordination number of the Ln(III) in both phases. In phase I, the Ln(III) ions are nine-coordinate with a tri-capped trigonal prism geometry and rectangular cavities with no solvent molecules. In phase II, the Ln(III) ions are eight-coordinate with a triangular dodecahedral geometry and distorted hexagonal cavities having two water molecules. These differences are due to the lanthanoid contraction. The magnetic properties show that the Ln(III) ions are isolated and do not present any noticeable magnetic interactions as expected for bromoanilato bridges and Ln(III) ions.     

Effect of the functionalization of the axial phthalocyanine ligands on the energy transfer in QD-based donor-acceptor pairs.

This study examines the electronic coupling between quantum dots (QDs) and molecules on their surfaces as a function of the modality of their interaction. As a probe, the energy transfer (ET) between CdSe QDs and phthalocyanines (Pcs) was monitored and evaluated with regard to the functionalization of the axial phthalocyanine ligand, bulkiness of the functional group bridging the QD donor and Pc acceptor, and the number of the functionalized axial ligands. New silicon PCs and their conjugates with CdSe QDs were synthesized. The ET efficiency and kinetics were studied by steady state and femtosecond time-resolved absorption spectroscopy. We observed a decrease in ET efficiency with the increase in functional group bulkiness, which could be explained by increasing steric hindrance between the ET pair. In addition, a higher ET efficiency was observed for amino and thiol functionalized Pcs compared to Pcs without functional group on the axial alkyl chain.     

Catalytic Alkyne Semihydrogenation with Polyhydride Ni/Ga Clusters

The bimetallic, decanuclear Ni₃Ga₇-cluster of the formula [Ni₃(GaTMP)₃(μ²-GaTMP)₃(μ³-GaTMP)] ( 1 , TMP=2,2,6,6-tetramethylpiperidinyl) reacts reversibly with dihydrogen under the formation of a series of (poly-)hydride clusters 2 . Low-temperature 2D NMR experiments at −80 °C show that 2 consist of a mixture of a di- ( 2_Di ), tetra- ( 2_Tetra ) and hexahydride species ( 2_Hexa ). The structures of 2_Di and 2_Tetra are assessed by a combination of 2D NMR spectroscopy and DFT calculations. The cooperation of both metals is essential for the high hydrogen uptake of the cluster. Polyhydrides 2 are catalytically active in the semihydrogenation of 4-octyne to 4-octene with good selectivity. The example is the first of its kind and conceptually relates properties of molecular, atom-precise transition metal/main group metal clusters to the respective solid-state phase in catalysis.     

Mutagenic, antimutagenic and antioxidant activities of a new class of beta-glucoside hydroxyhydroquinone from Anagallis monelli growing in Tunisia

A new skeleton of an O-heteroside natural substance named zinolol, the first representative of a new class of aminated hydroxyhydroquinone, has been isolated from the whole plant Anagallis monelli. Its structure has been established by one and two dimensional NMR spectroscopic procedures. Antioxidant, mutagenic, antimutagenic activities were realised and positive results were recorded.     

Lambda-type regioregular oligothiophenes: synthesis and second-order NLO properties

The synthesis of a new series of Lambda-type, D-Pi-A regioregular oligothiophenes is described. The simultaneous presence of the chiral centers and the Lambda-type structure disfavored the formation of centro-symmetrical dimeric assemblies. Hence, enhanced first hyperpolarizabilities betaHRS were measured in comparison with those of the corresponding monomers.