Plant bioelectrochemistry: effects of CCCP on electrical signaling in soybean

Carbonyl cyanide 3-chlorophenylhydrazone (CCCP) induces fast action potentials and decreases the variation potential in soybean plants. The propagation speed of the action potentials in a soybean plant produced by CCCP reaches up to 25 m/s. The duration of single action potentials after treatment by CCCP is 0.6 ms. The addition of CCCP to soil reduces variation or streaming potential to zero. The mechanism by which CCCP decreases plant maturation most likely includes depolarization of the plasma membrane, retardation of photosynthetic water oxidation, and respiratory electron transfer.     

Electrochemical oxidation behavior of 2,4-dinitrophenol at hydroxylapatite film-modified glassy carbon electrode and its determination in water samples

Hydroxylapatite (HAP)-modified glassy carbon electrode (GCE) was fabricated and used to investigate the electrochemical oxidation behavior of 2,4-dinitrophenol (2,4-DNP) by cyclic voltammetry, differential pulse voltammetry, and chronocoulometry. The oxidation peak current of 2,4-DNP at the modified electrode was obviously increased compared with the bare GCE, indicating that HAP exhibits a remarkable enhancement effect on the electrochemical oxidation of 2,4-DNP. Based on this, a sensitive and simple electrochemical method was proposed for the determination of 2,4-DNP. The effects of HAP concentration, accumulation time, accumulation potential, pH, and scan rate were examined. Under optimal conditions, the oxidation peak current of 2,4-DNP was proportional to its concentration in the range from 2.0 × 10⁻⁶ to 6.0 × 10⁻⁴ M with a correlation coefficient of 0.9987. The detection limit was 7.5 × 10⁻⁷ M (S/N = 3). The proposed method was further applied to determine 2,4-DNP in water samples with recoveries from 96.75% to 106.50%.     

Voltammetric and amperometric determination of 2,4-dinitrophenol metabolites

Methods for determination of 2-amino-4-nitrophenol and 4-amino-2-nitrophenol, metabolites of 2,4-dinitrophenol, were developed using differential pulse (DP) voltammetry and HPLC with amperometric and spectrophotometric detection. The applicability of these methods was tested by the determination of the analytes in model samples of urine after preliminary separation by solid-phase extraction. Voltammetry enabled parallel determination of both analytes, but its application in real matrix was severely limited due to the interference of other compounds present in urine. HPLC allowed the determination in real urine matrix down to micromolar concentrations; amperometric detection proved to be more sensitive and selective than the spectrophotometric one.     

Bioelectrochemical signaling in green plants induced by photosensory systems

Plants generate various types of intracellular and intercellular electrical events in response to environmental stress. The generation of electrophysiological responses induced by blue and red photosensory systems was observed in soybean plants. A phototropic response is a sequence of the following four processes: reception of a directional light signal, signal transduction, transformation of the signal into a physiological response, and the production of a directional growth response. It was found that the irradiation of soybean plants at 450+/-50, 670, and 730 nm induces action potentials with duration times and amplitudes of approximately 0.3 ms and 60 mV respectively.     

Thermodynamics of ionization of 2,4-dinitrophenol in water-dimethylsulfoxide solvents

The ionization constants of 2,4-dinitrophenol were measured in water-dimethylsulphoxide solvent mixtures at five temperatures ranging from 20 to 40°C. The enthalpy and entropy contributions to the ionization process are discussed. The results indicate that in water-rich solvent mixtures the ionization process is controlled by the entropy factor while in the dimethylsulphoxide-rich solvent mixtures it is controlled by the enthalpy factor.     

Voltammetric determination of 2,4-dinitrophenol and 2,5-dinitrophenol using a poly-aspartic acid modified electrode1

In pH 5.0, 0.1 mol l⁻¹ NaAc-HAc buffer solution, 2,4-dinitrophenol and 2,5-dinitrophenol exhibited sensitive and distinguishable voltammetric responses at the glassy carbon electrode modified with poly-aspartic acid. By measuring the reduction peak currents of nitro groups in different positions, dinitrophenol isomers have been determined simultaneously and quantitatively. The linear calibration ranges were 1.1 × 10⁻⁶–6.0 × 10⁻⁴ mol l⁻¹ for 2,4-dinitrophenol and 7.0 × 10⁻⁷–6.0 × 10⁻⁴ mol l⁻¹ for 2,5-dinitrophenol, with detection limits of 2.7 × 10⁻⁷ and 1.1 × 10⁻⁷ mol l-1 respectively. This method has been applied to the detection of dinitrophenols in simulation water sample, and the recovery was from 96.7 to 102.5%.     

Density functional theory study on electrochemical reduction of 2,4-dinitrophenol

Electrochemical reduction of 2,4-dinitrophenol was investigated by cyclic voltammetry (CV), square-wave voltammetry (SWV) and in situ UV-vis spectroelectrochemistry. The reduction peaks for 2,4-dinitrophenol predicted using density functional theory (DFT) method (B3LYP) with 6–31++g(d) and 6–31++g(d,p) basis sets are consistent with the experimental values. The reduction mechanism of 2,4-dinitrophenol is discussed.     

Spectroscopic studies on proton transfer equilibria: 2,4-dinitrophenol with several electron donors

The proton transfer equilibria of 2,4-dintrophenol with triethylamine, 1,4-diazabicyclo(2,2,2)octane, piperazine, N,N-dimethyl piperazine, N-methylacetamide, N,N-dimethylacetamide, N,N-dimethyl formamide and dimethyl sulfoxide have been studied in cyclohexane/carbon tetrachloride and benzene solvents by electronic absorption spectroscopy. Thermodynamic parameters for the proton transfer equilibria have been determined. It is shown that the extent of interaction between 2,4-dinitrophenol and the aprotic solvent determines the position of equilibrium.     

2,4-二硝基酚与二氟溴甲基膦酸二乙酯反应的研究

酚在碱性条件下与卤代烃反应生成相应的芳香醚,是典型的亲核取代反应,对于2,4-二硝基酚和二氟溴甲基膦酸二乙酯在碱性条件下的反应,其实验过程包括室温中和,甲苯回流脱水和亲核取代等三步反应。对产物进行了提纯和一系列的表征,结果发现主要生成了一种酚醚化合物。     

Spectroscopic studies on intra- and inter-molecular hydrogen bonding in 2,4-dinitrophenol and 3,5-dinitrosalicylic acid

Effect of solvent on the electronic spectral behaviour of 2,4-dinitrophenol (I) and 3,5-dinitrosalicylic acid (II) is examined and discussed. It is deduced that in case of (I) the intramolecular hydrogen bond to nitro breaks to form an intermolecular hydrogen bond depending upon the nature of solvent used whereas (II) remains intramolecularly hydrogen bonded to carbonyl group in solvents as strongly basic as DMF.     

Spectroscopic studies of electron donor-acceptor interactions: 2,4-dinitrophenol as an electron acceptor

The electron donor-acceptor interactions between 2,4-dinitrophenol and a series of π electron donors have been investigated in hexane by electronic absorption spectroscopy. The interaction is moderately strong. Linear correlations exist between spectroscopic and thermodynamic properties of complexes and the ionization potentials of donors. The charge transfer forces seem to explain the stability of complexes.     

Analysis and kinetics of 2,4-dinitrophenol in tissues by capillary gas chromatography--mass spectrometry

Five groups of six ICR mice were orally dosed with 22.5 mg/kg 2,4-dinitrophenol. Groups were sacrificed at 1, 3, 6, 12, and 24 h post treatment, and serum, liver, and kidney tissues were collected for analysis of dinitrophenol content. Quantitation was performed via a capillary gas chromatography--mass spectrometry technique after liquid--liquid extraction of biological specimens spiked with a trideuterated dinitrophenol internal standard. Concentration versus time data for each tissue were subjected to pharmacokinetic analysis. Similar two-compartment open models were found to characterize most phases of the disposition of this compound. The kidney appears to maintain a more persistent low concentration of 2,4-dinitrophenol.     

Calorimetric evaluation of activated carbons modified for phenol and 2,4-dinitrophenol adsorption

Two commercial activated carbons with differences in their superficial chemistry, one granular and the other pelletised, were modified for use in phenol and 2,4-dinitrophenol adsorption. In this paper, changes to the activated carbon surface will be evaluated from their immersion calorimetry in water and benzene, and they will then be compared with Area BET, chemical parameters, micropore size distributions and hydrophobicity factors of the modified activated carbons. The activated carbons were modified using 60 % solutions of phosphoric acid (H₃PO₄), nitric acid (HNO₃), zinc chloride (ZnCl₂) and potassium hydroxide (KOH); the activated carbon/solution ratio was 1:3 and impregnation was conducted 291 K for a period of 72 h before samples were washed until a constant pH was obtained. Water immersion calorimetry showed that the best results were obtained from activated carbons modified with nitric acid, which increased from ?10.6 to ?29.8 J g^?1 for modified granular activated carbon, and ?30.9 to ?129.3 J g^?1 for pelletised activated carbon. Additionally, they showed the best results in phenol and 2.4-dititrophenol adsorption. Those results indicate that impregnation with nitric acid under the employed conditions could generate a greater presence of oxygenated groups on their surface, which favours hydrogen bond formation and the increased adsorption of polar compounds. It should also be noted that immersion enthalpy in benzene for modified activated carbon with nitric acid is the method with the lowest value, which is consistent with the increased presence of polar groups on its surface. Regarding hydrophobicity factors, it was observed that granular carbons modified with nitric acid and potassium hydroxide have the lowest ratios, indicating greater interaction with water.     

Selective adsorption of 2,4-dinitrophenol on molecularly imprinted nanocomposites of mesoporous silica SBA-15/polyaniline

Surface imprinting and adoption of a nano-sized physical form are two effective approaches to overcome the template transfer difficulty within molecularly imprinted polymers (MIPs). This work is an attempt to conquer the problem of template transfer difficulty within MIPs by using a nano-reactor as a substrate for the reaction between the monomer and the template. Negatively charged hexagonal nano-channels of SBA-15 can act as a support for attachment of positively charged aniline monomers and the 2,4-dinitrophenol (2,4-DNP) template. The imprinted and non-imprinted SBA-15/polyaniline nanocomposites were characterized by Fourier transform infrared (FT-IR), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and nitrogen adsorption-desorption isotherms. The results showed that the synthesized polymer possessed a highly ordered mesoporous structure. The distribution coefficient values of 2,4-DNP, K(d (2,4-DNP)), were estimated as 301.4 ± 2.3 and 101.2 ± 1.0 mL g(-1) for imprinted and non-imprinted polymers (NIP), respectively. The MIP-solid-phase extraction (SPE) process was optimized by evaluating the type of washing solvent and the composition and volume of the eluting solvent. The prepared MIP was used as a selective sorbent for SPE of 2,4-DNP in the presence of phenolic compounds in tap and sea water. The experimental results indicated that the MIP-SPE and NIP-SPE column yielded recoveries higher than 96% and 38%, respectively. The R.S.D. values were also lower than 3.2% and 4.6% for MIP-SPE and NIP-SPE, respectively.     

2,4-二氯苯酚的电化学氧化降解反应研究

采用循环伏安法和原位红外光谱技术研究了2,4-二氯苯酚在Pt电极上的电化学氧化降解反应,结合Fukui函数值预测了2,4-二氯苯酚在电化学氧化过程中的反应位点. 结果表明,Pt电极对2,4-二氯苯酚有良好的电催化活性,2,4-二氯苯酚在电极表面反应主要有3个途径：直接通过电化学反应脱去氯离子,生成苯酚;在·OH的进攻下,C—Cl键断裂,4位Cl较2位Cl先脱去,生成苯二酚,并可进一步氧化生成苯醌以及不饱和羧酸;在·OH的进攻下发生苯环开环反应,生成含氯不饱和羧酸. 在1700 mV左右,2,4-二氯苯酚可经电化学氧化生成CO₂.     

Electrochemical behaviour of cellulosic cation membranes: Bi-ionic potentials in alkali systems

The behaviour of cationic ion-exchange membranes in bi-ionic systems formed by pairs of alkali ions was studied. The membrane was prepared by grafting vinyl monomers on parchment paper, which gives it a marked hydrophilic character. The selectivity coefficients and bi-ionic potentials of the membrane in the presence of the ten possible pairs of alkali ions was measured in a wide range of electrolyte concentrations (10⁻³−1 molal). The magnitude of these parameters is governed by the ions forming the bi-ionic system and their values are the higher the greater the difference in size of the ions. For those ion-pair systems formed from identical ions, both selectivity coefficients and bi-ionic potentials remain constant as the electrolyte concentration increases, whereas for those systems made up of dissimilar ions, the values are dependent on the concentration of electrolyte. The results are justified on the basis of the hydrophilic character of the membrane matrix.     

Synthesis,SAR and in vitro therapeutic potentials of thiazolidine-2,4-diones

Background

Thiazolidinedione is a pentacyclic moiety having five membered unsaturated ring system composed with carbon, oxygen, nitrogen and sulfur molecules at 1 and 3 position of the thiazole ring and widely found throughout nature in various form. They favourably alter concentration of the hormones secreted by adipocytes, particularly adiponectin. They also increase total body fat and have mixed effects on circulating lipids. Thiazolidinedione nucleus is present in numerous biological moieties and has different pharmacological activities likes, e.g. antimalarial, antimicrobial, antimycobacterial, anticonvulsant, antiviral, anticancer, anti-inflammatory, antioxidant, anti-HIV (human immunodeficiency virus) and antituberculosis.

Results and discussion

The synthesized compounds were screened for their in vitro antimicrobial potential against Gram (positive and negative) bacterial and fungal strains by tube dilution technique. In this series, compound 10 exhibited significant antimicrobial activity against B. subtilis and S. aureus with MIC?=?4.2?×?10^?2 µM/ml, compound 15 showed significant activity against K. pneumonia with MIC?=?2.60?×?10^?2 µM/ml and compound 4 displayed potent antibacterial activity against E. coli with MIC?=?4.5?×?10^?2 µM/ml. Compound 10 had most potent antifungal activity against C. albicans and A. niger with MIC?=?4.2?×?10^?2 µM/ml. Compounds 12 and 15 were found as most active antidiabetic agents having IC₅₀?=?27.63 μg/ml and 22.35 μg/ml, respectively, using DPPH assay. Antioxidant activity results indicated that compounds 3 and 9 displayed good antioxidant agent with IC₅₀?=?29.04 μg/ml and 27.66 μg/ml respectively, using α amylase assay.

Conclusion

All the synthesized derivatives exhibited good antimicrobial, antidiabetic and antioxidant activities using specific methods then compared with mentioned standard drugs. Especially, compounds 3, 4, 9, 10, 12 and 15 displayed highest activity. Structure activity relationship demonstrated that presence of electron withdrawing group (o-NO₂, p-Cl, p-Br) enhanced the antibacterial activity against E. coli as well as increased the antioxidant activity while the presence of electron releasing group (o/p-OCH₃, 3,4,5-trimethoxy) enhanced the antibacterial activity against S. aureus, B. subtilis, S. typhi, K. pneumonia, C. albicans and A. niger as well as the antidiabetic activity.

     

Spectroscopic and Electrochemical Characterization of Iron(II) and 2,4-Dinitrotoluene

The objective of this work was the development of reliable methods to determine 2,4-dinitrotoluene, a precursor to explosives. A complex between Fe(II) ion and 2,4-dinitrotoluene was formed in solution and characterized by ultraviolet-visible absorption spectroscopy using Job’s plots and attenuated total reflection-Fourier transform infrared spectroscopy. Surface modification of glassy carbon electrodes were performed with iron nanoparticles via electrochemical reduction of iron(II). The modified electrode was employed for the determination of 2,4-dinitrotoluene. Scanning electron micrographs showed that the iron nanoparticles were incorporated on the surface of glassy carbon electrode. The electrochemical determination of 2,4-dinitrotoluene was performed by cyclic voltammetry using the modified electrode. The iron modified electrode produced larger reduction currents than the unmodified electrode for the same concentration of 2,4-dinitrotoluene. Concentrations of 2,4-dinitrotoluene as low as 10 parts per billion were determined using the modified electrode.