Comparative study between two fabricated potentiometric sensors to enhance selectivity towards ferrous ions

Electroanalytical methods are highly selective for measuring electrical quantities including the charge, potential and current with their relation to chemical parameters. They are widely applied in various fields such as biochemical analysis, industrial quality control and environmental monitoring. They have many advantages over other techniques in that they are not time consuming and are specific for certain oxidation states of certain elements which give these techniques high selectivity and sensitivity features. This paper is based on two parts: the first part describes the fabrication of screen‐printed electrodes (SPEs) modified with methyl red as electroactive material, while second part describes the preparation and characterization of Fe(II)–methyl red complex using various spectroscopic tools, the complex being used for the construction of carbon paste electrodes (CPEs). The two proposed electrodes were successfully applied for the determination of Fe(II) in water and pharmaceutical (pharovit) samples. The electrodes under investigation show potentiometric response for Fe(II) in the concentration range 8.0 × 10^?7–1.0 × 10^?2 and 5.0 × 10^?7–1.0 × 10^?2 M at 25°C for SPE and CPE, respectively, and the electrode response is independent of pH in the range 1.5–7.0. These sensors show Nernstian slopes of 29.1 ± 0.2 and 29.7 ± 0.16 mV decade^?1 with detection limit values of 8.0 × 10^?7 and 5.0 × 10^?7 M for SPE and CPE, respectively. These electrodes show fast response time of 6 and 4 s and exhibit a lifetime of 100 and 30 days for SPE and CPE, respectively. The mechanism of chemical reaction between modifier and Fe(II) on the SPE surface was studied using infrared spectra, scanning electron microscopy and energy‐dispersive X‐ray analysis. The proposed potentiometric method was validated according to the IUPAC recommendations. The results obtained using the proposed sensors were comparable with those obtained with inductively coupled plasma analysis.     

Decomposition of group rings and the converse of Schur’s lemma

In this work, we give necessary and su?cient conditions for a group ring (of finite group) to satisfy the converse of Schur’s lemma for group rings of finite groups. Rings considered here are commutative or noncommutative perfect. Some cases of twisted group rings are studied. Also we introduce the notion of semi-CSL ring.     

Isoxazolopyrimidinethione and Isoxazolopyridopyrimidinethione Derivatives: Key Intermediates for Synthesis of Novel Fused Triazoles as Potent 5α‐Reductase Inhibitors and Anti‐Prostate Cancer

The arylideneisoxazolone derivative 1 is used for preparation of two different pyrimidinethiones 3 and 5 through interaction with thiourea and thiouracil, respectively. Compounds 3 and 5 were subjected to reaction with different hydrazonyl halides in basic medium to afford different triazolopyrimidines 9a , 9b , 9c , 9d , 9e , 9f , 9g , 9h and 13a , 13b , 13c , 13d , 13e , 13f , the structures were confirmed by their spectral and elemental analysis. All the newly synthesized products were screened against 5α‐reductase. Some of the newly synthesized compounds showed potent 5α‐reductase inhibition activities with good ED₅₀.     

Conductimetric Studies of Charge Transfer Complexes of p‐Chloranil with Some Alicyclic Amines in Polar Media

The stoichiometry of charge‐transfer complexes which ionise in polar media has been studied by conductimetric titration technique in the systems morpholine‐p‐chloranil (CA), piperidine‐CA and pyrrolidine‐CA in three different polar solvents namely N,N‐dimethylformamide, acetonitrile and dimethylsulfoxide at different temperatures of 10, 15, 18, 20, 25 and 30 °C. The stoichiometric ratios of these complexes were found to vary from 1:1 to 1:4 (acceptor: donor) depending on the system, temperature and solvent used. The ασ_M‐values of these complexes have been reported. The effect of solvents, temperatures and types of electron donors on the σ_P‐values has been examined.     

Mod-retractable strongly π-regular rings and group algebras

Abstract

In this work, we show that a two-sided mod-retractable and strongly π-regular ring is two-sided semiartinian. On the other hand, a strongly π-regular von Neumann regular ring is left mod-retractable if and only if it is a left semiartinian V-ring. We apply these results to group algebras and thereby we give the complete structure of groups whose group algebras are mod-retractable.

Communicated by Toma Albu     

Synthesis of 1,3,4‐Oxadiazole Acyclo C‐Nucleosides Bearing 5‐Methylthio{7‐substituted‐1,2,4‐triazolo[1,5‐d]tetrazol‐6‐yl}moieties

Oxidative cyclization of the sugar hydrazones ( 3_a‐f ) derived from {7H‐1,2,4‐triazolo[1,5‐d]tetrazol‐6‐ylsulfanyl}acetic acid hydrazide ( 1 ) and aldopentoses 2_a‐c or aldohexoses 2_d‐f with bromine in acetic acid in the presence of anhydrous sodium acetate, followed by acetylation with acetic anhydride gave the corresponding 2‐(per‐O‐acetyl‐alditol‐l‐yl)‐5‐methylthio{7H‐1,2,4‐triazolo[1,5‐d]tetrazol‐6‐yl}‐1,3,4‐oxadiazoles ( 5_a‐f ). Condensative cyclization of the sugar hydrazones ( 3_a‐f ) by heating with acetic anhydride gave the corresponding 3‐acetyl‐2‐(per‐O‐acetyl‐alditol‐1‐yl)‐2,3‐dihydro‐5‐methylthio{7‐acetyl‐1,2,4‐triazolo[1,5‐d]tetrazol‐6‐yl}‐1,3,4‐oxadiazoles ( 11_a‐f ). De‐O‐acetylation of the acyclo C‐nucleoside peracetates ( 5 and 11 ) with methanolic ammonia afforded the hydrazono lactones ( 7 ) and the acyclo C‐nucleosides ( 12 ), respectively. The structures of new oxadiazole derivatives were confirmed by analytical and spectral data.     

Tandem Hydroformylation/Reductive Amination of 3‐Allyl‐2‐methylquinazolin‐4(3H)‐one

The 3‐allyl‐2‐methylquinazolin‐4(3H)‐one ( 1 ), a model functionalized terminal olefin, was submitted to hydroformylation and reductive amination under optimized reaction conditions. The catalytic carbonylation of 1 in the presence of Rh catalysts complexed with phosphorus ligands under different reaction conditions afforded a mixture of 2‐methyl‐4‐oxoquinazoline‐3(4H)‐butanal ( 2 ) and α,2‐dimethyl‐4‐oxoquinazoline‐3(4H)‐propanal ( 3 ) as products of ‘linear’ and ‘branched’ hydroformylation, respectively (Scheme 2). The hydroaminomethylation of quinazolinone 1 with arylhydrazine derivatives gave the expected mixture of [(arylhydrazinyl)alkyl]quinazolinones 5 and 6 , besides a small amount of 2 and 3 (Scheme 3). The tandem hydroformylation/reductive amination reaction of 1 with different amines gave the quinazolinone derivatives 7 – 10 . Compound 10 was used to prepare the chalcones 11a and 11b and pyrazoloquinazolinones 12a and 12b (Scheme 4).     

Development and characterization of nonpeptidic small molecule inhibitors of the XIAP/caspase-3 interaction

Elevated expression of inhibitor of apoptosis protein (IAP) family members in various types of cancers is thought to provide a survival advantage to these cells. Thus, antiapoptotic functions of IAPs, and their potential as novel anticancer targets have attracted considerable interest. Among the IAPs, the X chromosome-linked inhibitor of apoptosis protein (XIAP) is regarded as the most potent suppressor of mammalian apoptosis through direct binding and inhibition of caspases. A high-throughput biochemical screen of a combinatorial chemical library led to the discovery of a novel nonpeptidic small molecule that has the ability to disrupt the XIAP/caspase-3 interaction. The activity of this nonpeptidic small molecule inhibitor of the XIAP/caspase-3 interaction has been characterized both in vitro and in cells. Molecules of this type can be used to conditionally inhibit the cellular function of XIAP and may provide insights into the development of therapeutic agents that act by modulating apoptotic pathways.     

6-exo versus 7-endo iodolactonizations of 2-(alkynyl)phenylacetic acids

Exposure of 2-alkynylphenylacetic acids to excess iodine in acetonitrile containing anhydrous potassium carbonate delivers good yields, either of the corresponding isochroman-3-ones or benzo[d]oxepin-2(1H)-ones, depending upon the alkyne substituent: when this is alkyl, the former 6-exo products dominate, otherwise the 7-endo products are formed largely or, more often, exclusively.