Phosphorus–nitrogen compounds: Part 19. Syntheses,structural and electrochemical investigations,biological activities,and DNA interactions of new spirocyclic monoferrocenylcyclotriphosphazenes

The reactions of hexachlorocyclotriphosphazatriene, N₃P₃Cl₆, with N-alkyl-N-ferrocenylmethylethylene diamines, FcCH₂NH(CH₂)₂NHR₁ [R₁ = Me (1) and Et (2)], and sodium [3-(N-ferrocenylmethylamino)-1-propanoxide] (3) produce spirocyclic monoferrocenyl tetrachlorophosphazenes (1a–3a). The tetrapyrrolidinophosphazenes (1b–3b) are prepared from the reactions of corresponding phosphazenes (1a–3a) with excess pyrrolidine. The reaction of 1a with excess morpholine affords geminal-morpholino phosphazene (1c), whilst the reactions of 2a and 3a give diethylaminotrimorpholino (2c) and fully substituted morpholino products (3c), respectively. The structural investigations of the compounds are examined by Fourier transform IR, MS, ¹H, ¹³C, ³¹P NMR, DEPT, HETCOR, and HMBC techniques. The crystal structures of 3b and 3c are determined using X-ray crystallography. Cyclic voltammetric and chronoamperometric data show that compounds 1a–3a, 1b–3b, and 1c–3c exhibit electrochemically reversible one-electron oxidation of Fc redox centers which are hardly affected by the substituents on the phosphazene ring. The compounds 1b, 2b, 3b, and 3c are screened for antibacterial activities against Gram-positive and Gram-negative bacteria and for antifungal activities against yeast strains. In addition, the antituberculosis activities (in vitro) of these compounds are evaluated against INH-susceptible reference strain M. tuberculosis H37Rv, and six multi-drug resistant clinical M. tuberculosis isolates. Compound 2b is found to be the most active against the susceptible the reference strain. In addition, 1b, 2b, and 3c are active against all the multidrug-resistant clinical isolates at the highest concentrations. Gel electrophoresis data indicate that the compounds promote the formation of strand breaks in plasmid DNA. Almost all the concentrations lost of supercoiled DNA suggests that the compound 3b is very efficient plasmid-modifier. The compounds inhibit BamHI cleavage of pUC18 DNA while restricting HindIII.     

Carbon nanotubes/alizarin red S–poly(vinylferrocene) modified glassy carbon electrode for selective determination of dopamine in the presence of ascorbic acid

A modified electrode was fabricated by electrochemical formation of poly(vinylferrocene) on the multi-wall carbon nanotube-alizarin red S matrix covered glassy carbon electrode. A higher electrochemical activity was obtained to the electrocatalytic oxidation of dopamine. The electrode surface was characterized electrochemically and spectroscopically. Poly(vinylferrocene) (PVF) in electrode was used as an electron transfer mediator in the electrochemical oxidation of compounds due to its perfect reversible redox properties. Multi-wall carbon nanotubes (MWCNTs) / alizarin red S (ARS)–PVF electrode was used to the determination of dopamine in the presence of ascorbic acid in 0.1 M sulphate buffer solution at pH 7. The performance of the MWCNTs/ARS–PVF electrode was evaluated by DPV and amperometry.     

Extremely Increasing the Operating Frequency Range of Mode-Locked Hybrid Soliton Pulse Source

Numerical simulations show that proper fundamental mode-locking repetition range of hybrid soliton pulse source where transform-limited pulses are obtained is extremely increased with the use of linearly chirped tanh apodized fibre Bragg grating. Near transform-limited pulses around a system operating frequency of 2.5 GHz. are generated over a frequency range of 1.6 GHz （1.9-3.4 GHz）     

Sulfate decomposition by bacterial leaching

Sulfate disposal is the main problem of many industrial effluents, such as excess sulfuric acid, gypsum, coal desulfurization byproducts, acid-mine waters, and general metallurgical effluents. It has been established that sulfate present in wastes can be converted to elemental sulfur by bacterial mutualism. This study presents the results of an investigation of the industrial feasibility of utilizing a biological system capable of converting hydrous calcium sulfate (gypsum) to elemental sulfur. Gypsum, which was used in this study, is a byproduct of the fertilizer industry. The biological system is referred to as a bacterial mutualism, and involvesDesulfovibrio desulfuricans for sulfate conversion andChlorobium thiosulfatophilum for hydrogen sulfide conversion. Bacterial mutualism and utilization of sulfate were investigated by means of a two-stage anaerobic system. In the first stage, a gas purge system was used for sulfate conversion to sulfide, and it was found that maximum conversion is 34%. In the second stage, a static culture system was used for sulfide conversion to sulfur with a conversion of 92%.     

Simultaneous Determination of Thiocolchicoside and Diclofenac Diethyl Ammonium in Topical Gel Formulation by Square Wave Voltammetric Method

Russian Journal of Electrochemistry - A rapid, simple, sensitive, precise and specific square wave voltammetric method was developed for the simultaneous determination of Thiocolchicoside (TC) and...     

Phosphorus-nitrogen compounds. 14. Synthesis, stereogenism, and structural investigations of novel n/o spirocyclic phosphazene derivatives

The reactions of hexachlorocyclotriphosphazatriene, N3P3Cl6, with N/O donor-type N-alkyl-o-hydroxybenzyl- and o-hydroxynaphthylamines result in novel mono- (3a, 4a and 4b), di- (5a and 5b), and tri- (3b, 6a, and 6b) spirocyclic phosphazene derivatives. The tetrakis-pyrrolidinophosphazene, 3b, has been obtained from the reaction of partly substituted compound 3a with the excess pyrrolidine in tetrahydrofuran. The relationship between the endocyclic NPN (alpha) and exocyclic NPO (alpha') bond angles of the analogous spirocyclic phosphazenes with the deltaP shifts of NPO phosphorus atoms have been presented. It was observed that there is a linearity between alpha angles and deltaP shifts, while no linear relationship has been observed for alpha' angles. In addition, we have found the correlation between Delta(P-N) and deltaNPO shifts, which implies a linear relationship. Delta(P-N)=(a-b), where a and b are the average lengths of two adjacent P-N bonds. The structural investigations of all of the compounds have been made by elemental analyses; mass spectrometry; Fourier transform infrared spectroscopy; one-dimensional 1H, 13C, and 31P NMR; distortionless enhancement by polarization transfer; and two-dimensional correlation spectroscopy, heteronuclear shift correlation, and heteronuclear multiple-bond correlation homo- and heteronuclear correlation techniques. The solid-state structures of 3a, 4a, 4b, and 5a have been determined by X-ray crystallographic techniques. The asymmetric units of compounds 3a and 4a contain two independent molecules, and 3a has strong intermolecular N-H...N hydrogen bonds linking three phosphazene rings. The molecular structure of 6a looks like a propeller where the chemical environment of P1 is different from that of P2 and P3. On the other hand, compounds 5a and 5b are expected to exist as cis- or trans-geometric isomers and to be in cis (meso) or trans (racemic) configurations. The crystallographic and preliminary chiral solvating agents results show that both of them are trans (racemic). In addition, 6a and 6b are also expected to exist as cis-trans-trans- and cis-cis-cis-geometric isomers; both of them are found to be in cis-trans-trans geometries. According to the two-dimensional spectroscopic data, the possible conformations of 3a and 4a in CDCl3 are the same with the solid-state structures.     

Small signal intensity modulation of external cavity lasers with fiber Bragg gratings

The small signal intensity modulation (IM) of a hybrid soliton pulse source (HSPS) utilizing Gaussian apodized fiber Bragg grating (FBG) is described using electric field approach. The HSPS is modeled by a time-domain solution of the coupled-mode equations. It is shown that type of external cavity is important effect on resonance peak spectral splitting (RPSS) in IM response as well as effect of laser and FBG parameters. It is also shown that the RPSS can be suppressed by using linearly chirped Gaussian apodized FBG as an external cavity insted of Gaussian apodized FBG.     

Purification and Properties of the diamine oxidase of pea seedlings

Enzymes have been used extensively in many industries for the last 20 yrs. The purpose of this study was the isolation, purification, and specification of diamine oxidase (DAO) of pea seedlings. The relationship between enzyme activity and growth conditions has been investigated. DAO that was extracted from pea seedlings was purified by centrifugation, thermal denaturation, fractionation with ammonium sulfate, precipitation of inert components, column electrophoresis, and DEAE-cellulose column chromatography. It was found that the final enzyme preparation is 400-fold purer than the original extract at the end of the purification steps. The molecular weight, isoelectric point, and copper content of the purified enzyme also were determined.     

Voltammetric Determination of Cefuroxime Axetil in Pharmaceuticals Using Graphene Oxide Modified Glassy Carbon Electrode and Hanging Mercury Drop Electrode

Russian Journal of Electrochemistry - Two novel, economic, rapid, simple, sensitive and selective square wave voltammetric (SWV) methods have been developed for the determination of cefuroxime...     

Simultaneous determination of tiopronin and its primary metabolite in plasma and ocular tissues by HPLC

Tiopronin, formally 2‐mercaptopropionylglycine (MPG), is currently prescribed to treat cystinuria and rheumatoid arthritis, and its antioxidant properties have led to its investigation as a treatment for cataracts, a condition in which oxidative stress is strongly implicated. To study its accumulation in the eye, a reliable, isocratic HPLC method was developed for the determination of MPG and its primary metabolite 2‐mercaptopropionic acid (MPA) in plasma and relevant ocular tissues. This method utilizes pre‐column derivatization and fluorescence detection. The 3.5 min separation enables high‐throughput analysis, and validation experiments demonstrated that this method is suitable for evaluating ocular accumulation of MPG and MPA at concentrations as low as 66 and 33 nm , respectively. Excellent linearity was achieved over the working concentration range with R² > 0.997. Extraction recovery was reproducible within each matrix and exceeded 97%. Accuracy was within 13.3% relative error, and intra‐ and inter‐day precisions were within 6% CV and 7% CV, respectively. Sample stability was demonstrated under various storage conditions, and the use of an internal standard conferred exceptional ruggedness. This method has been successfully applied for the determination of MPG and MPA in plasma, cornea, lens and retina following intraperitoneal administration of the drug in Wistar rats.