Adsorption of Co2+, Ni2+, Cu2+, and Zn2+ onto amorphous hydrous manganese dioxide from simple (1-1) electrolyte solutions

The adsorption of Co2+, Ni2+, Cu2+, and Zn2+ onto amorphous hydrous manganese dioxide (delta-MnO2) has been studied using two methods, viz., isotherms at constant pH in the presence of buffer solution and pH variation in the absence of buffer solution from a fixed metal ion concentration. While the adsorption isotherm experiments were carried out in 0.5 M NaCl only, pH variation or batch titration experiments were carried out in 0.5 M NaCl, 0.01 M NaCl, and 0.01 M KNO3 solutions. The complex nature of adsorption isotherms at constant pH values indicates that adsorption of all the cations is non-Langmuirian (Freundlich) and takes place on the highly heterogeneous oxide surface with different binding energies. The proton stoichiometry derived from isotherms at two close pH values varies between 0.3 and 0.8. The variation of fractional adsorption with pH indicates that the background electrolyte solution influences the adsorption of cations through either metal-like or ligand-like complexes with Cl-, the former showing a low adsorption tendency. The proton stoichiometry values derived from the Kurbatov-type plot varies not only with the electrolyte solution but also with the adsorbate/adsorbent ratio. The variation of fractional adsorption with pH can be modeled either with the formation of the SOM+ type or with a combination of SOM+ and SOMOH type complexes, depending upon the cation and electrolyte medium. The equilibrium constants obtained from Kurbatov-type plots are found to be most suitable in these model calculations. Adsorption calculated on the basis of ternary surface metal-chlorocomplex formation exhibits very low values.     

Thienoisoindigo‐based small molecules and narrow bandgap polymers synthesized via C–H direct arylation coupling

Thienoisoindigo (TIIG) has emerged as an attractive building block for high‐performance organic optoelectronic devices. Here we report the first synthesis of a series of π‐conjugated TIIG‐based small molecules and alternating copolymers via direct C–H arylation, which enables the efficient synthesis without use of flammable and toxic orgametallic reagents in fewer steps compared Suzuki and Stille coupling. The direct arylation coupling between TIIG and two respective mono‐bromo aryl reactants clearly shows that the α‐H is more reactive than the β‐H in the thiophene unit of TIIG. The high regioselectivity of TIIG monomer warrants the successful synthesis of high‐quality alternating copolymers with minimal structural defects. PTIIG‐BT polymer synthesized via direct arylation polymerization (DAP) showed comparable molecular weight and hole mobility than the same polymer previously synthesized via Suzuki coupling. Moreover, the two new polymers (PTIIG‐TF and PTIIG‐2FBT) synthesized via DAP showed hole mobility up to 10^?3 cm² V^?1 s^?1 in FET devices fabricated and tested under ambient conditions. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2015–2031     

Application of Pigeon Pea (Cajanus cajan) Stalks as Raw Material for Xylooligosaccharides Production

Pigeon pea (Cajanus cajan) is a perennial plant widely cultivated in tropical and subtropical regions of many countries. The present studies aimed to produce xylooligosaccharides (XOS) from pigeon pea stalks in order to do value addition. The chemical analysis of stalks revealed 18.33?±?1.40 % hemicelluloses in addition to cellulose, protein, and lignin. Sodium hydroxide coupled with steam application enabled almost 96 % recovery of original xylan, present in the pigeon pea stalks. Enzymatic hydrolysis of xylan led to production of XOS namely, xylobiose and xylotriose. Response surface model indicated a maximum yield of xylobiose (0.502 mg/ml) under the hydrolysis conditions of pH 4.91, temperature at 48.11 °C, enzyme dose at 11.01 U, and incubation time at 15.65 h. The ideal conditions for higher xylotriose yield (0.204 mg/ml) were pH 5.44, temperature at 39.29 °C, enzyme dose at 3.23 U, and incubation time at 15.26 h. The present investigation was successful in assessing the prospect of using pigeon pea stalks as a raw material for xylan extraction vis-à-vis XOS production.     

Adsorption of Co2+, Ni2+, Cu2+ and Zn2+ from 0.5 M NaCl and major ion sea water on a mixture of delta-MnO2 and amorphous FeOOH

The pH(pzc) values of several mechanical mixtures of amorphous hydrous oxides of iron (amorphous FeOOH) and manganese (delta-MnO2) have been determined using the solid addition method. While the pH(pzc) of delta-MnO2 remains almost unchanged, the corresponding value for amorphous FeOOH tends to increase with increased proportion of delta-MnO2 in the mixtures. The adsorption behavior of Co2+, Ni2+, Cu2+, and Zn2+ with respect to pH on a mechanical mixture of 70% delta-MnO2 and 30% amorphous FeOOH from 0.5 M NaCl and major ion sea water has been studied. Since delta-MnO2 is much more active adsorbent than amorphous FeOOH at pH below 6.5, the adsorption data on mixture have not only been normalized with respect to the mass of delta-MnO2 in the mixture, but also compared with adsorption data on delta-MnO2 alone. It is interesting to note that though each trace metal behaves in a different way from the other especially with respect to the nature of electrolyte medium, it is generally observed that the adsorption on the mixed oxide system is higher than that on delta-MnO2 alone under similar condition. It is also observed that adsorption in major ion sea water at a particular pH value is lower than in 0.5 M NaCl solution.     

Investigating the potential of tetrahydropyridinyl chalcones as useful agents against breast carcinoma: An in vitro and in vivo study

N-Benzyltetrahydropyridinyl-4,6-dimethoxy phenyl-substituted 2′-hydroxychalcones SJC1–15 were synthesized using Claisen–Schmidt condensation, their structures confirmed by spectral analysis, and their anticancer activity evaluated. To support their biological activity, physicochemical parameters such as lipophilicity and oxidation potential were determined. To assess their relative cytotoxicity, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed using MCF-7, T-47D, MDA MB-231, HepG₂, and Vero cell lines. The cytotoxicity of the chalcones was found to vary with the nature of the ring B substituents. The lipophilicity of the cytotoxic compounds expressed in terms of distribution coefficient was found to lie in the range of 2.4–4.2. Further evaluation of their antioxidant potential revealed antioxidant activity by 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging assay and irreversible electrochemical reaction with oxidation potential in the range of 0.879–1.048 V. Of the 15 chalcones, SJC4, 5, 9 were selected for further in vitro studies using MCF-7. The compounds exhibited significant apoptotic effect and caused cell cycle arrest at G0/G1 and G2/M phase. Among them, two of the O-alkylated chalcones (SJC5, 9) showing promising activity against hormone-responsive breast cancer cells were evaluated for their in vivo anticancer activity using 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary tumor model. Three-week treatment with the test compounds at oral dosage of 100 mg kg^?1 per day significantly improved elevated tumor parameters compared with tumor control. Treatment with chalcone SJC5 (a 2,4,5-trimethoxy derivative) exhibited anticancer effects similar to those of doxorubicin (2 mg kg^?1 per week, i.p.) and was free from toxic effects observed with doxorubicin treatment.     

The Electrical Double Layer at Hydrous Manganese Dioxide/Electrolyte Interface

We present here a study of a tetrathiafulvalene derivative, tetrakis(octadecylthio)tetrathiafulvalene (TTFH), arranged in LB films together with a detailed characterization process by means of UV-vis, IR, SEM, and X-ray diffraction that has allowed us to propose a packing model. These films were exposed to iodine vapor and this doping process was carefully followed using UV-vis and IR spectroscopy. The redox properties of the TTFH were studied in both organic solution and LB films. The results have been interpreted in terms of the molecular structure and the LB film architecture. Copyright 2001 Academic Press.     

Adsorption of Co, Ni, Cu, and Zn on hydrous manganese dioxide from complex electrolyte solutions resembling sea water in major ion content

Adsorption of Co, Ni, Cu, and Zn onto a poorly crystalline hydrous manganese dioxide (delta-MnO2) has been studied in complex electrolyte solutions such as (a) 0.5 M NaCl+0.054 M MgCl2, (b) 0.5 M NaCl+0.028 M Na2SO4, and (c) artificial sea water prepared according to the standard literature method. These three solutions allow us to identify the specific effect of major cations, major anions, and the mixture of major cations and anions (including carbonate and bicarbonate) that is present in real sea water. The adsorption isotherm in major ion sea water at pH 7.25 indicates that while Co and Zn exhibit increases in adsorption with increase in concentration, Ni shows relatively poor adsorption, reaching a plateau at 0.075 mM concentration. The three trace metals (Co, Ni, and Zn) show Langmuirian behavior for adsorption at low concentration. It is generally observed that the fractional adsorption vs pH curve shifts to higher pH either in the presence of 0.054 M MgCl2 or in sea water. In the presence of 0.028 M Na2SO4 the fractional adsorption vs pH curve remains almost unchanged with respect to a 0.5 M NaCl solution. The competitive adsorption of one trace metal in the presence of other three in major ion sea water indicates that this phenomenon is more predominant with Ni and Zn than with Co and Cu.     

Computational identification of novel piperidine derivatives as potential HDM2 inhibitors designed by fragment-based QSAR,molecular docking and molecular dynamics simulations

Tumor suppressor protein p53 maintains integrity of genome and regulates the genes responsible for DNA repair mechanism, apoptosis as well as cell cycle and growth arrest. As with murine double minute 2 (MDM2), the human homolog HDM2 is a principal cellular antagonist of p53. In unstressed cells, cellular levels of p53 and HDM2 are maintained in an autoregulatory manner in which both mutually control cellular levels of each other. About half of the human cancers express wild-type p53 protein that is antagonized by over-expressed HDM2. Restoring p53 function via HDM2 antagonists is a leading therapeutic approach for treating a variety of tumors. In this study, we have developed a novel statistically sound group-based QSAR (GQSAR) model using piperidine-derived compounds that have been validated experimentally to inhibit p53–HDM2 interaction. On the basis of developed GQSAR model, a combinatorial library of molecules was prepared and its activity was predicted. These molecules were then docked to HDM2, and two top-scoring molecules possessing a binding energy of ?6.639 and ?6.305 kcal/mol were selected for further study. These molecules and their binding poses were analyzed further via molecular dynamic simulations. In this study, we report two lead compounds as potent HDM2 inhibitors and also provide an insight into mechanism of interaction of the lead compounds to HDM2 target.

     

Inter-relationship between optical dielectric constant and interatomic separation of mixed crystals in ionic and covalent binary compound families

An ion dependent dielectric model is developed for mixed binary crystals. The interatomic separation (R) and optical dielectric constant (ε_∞) of the mixed crystals are computed from the measured values of R and ε_∞ of pure crystals. An empirical relation between ε_∞ and R is therefore found for mixed crystals by using the computed values. It is found that the dielectric behaviour of ionic mixed crystals is cation dependent while that of covalent mixed crystals is anion dependent. The prescribed theory can therefore be used to form different mixed crystals with particular values of ε_∞ required in any specific opto-electronic devices.