A. Varada Reddy

The use of an agricultural waste material, Jujuba seeds for the removal of anionic dye (Congo red) from aqueous medium

The feasibility of using Indian Jujuba Seeds (IJS) (Zizyphus maruritiana), abundantly available in and around the Nallamalla forest in Andhra Pradesh, for the anionic dye (Congo red, CR) adsorption from aqueous solution, has been investigated as low cost and eco-friendly adsorbent. Adsorption studies were conducted on a batch process, to study the effects of contact time, initial concentration of CR, pH and temperature. Maximum colour removal was observed at pH 2. The equilibrium data was analyzed by the Langmuir, the Freundlich and the General isotherms. The data fitted well with the Langmuir model, with a maximum adsorption capacity of 55.56 mg g(-1). The pseudo-second-order kinetics was the best for the adsorption of CR, by IJS (Z. maruritiana) with good correlation. Thermodynamic parameters, such as standard free energy change (ΔG°), standard enthalpy change (ΔH°) and standard entropy change (ΔS°), were analyzed. The results suggest that IJS (Z. maruritiana) is a potential low-cost adsorbent for the CR dye removal from synthetic dye wastewater.

Simple and rapid biosynthesis of stable silver nanoparticles using dried leaves of Catharanthus roseus. Linn. G. Donn and its anti microbial activity.

Nanoparticles have been used to alter and improve the pharmacokinetic and pharmacodynamic properties of various types of drug molecules. The plant extracts are eco-friendly, economical and cost effective for synthesis of large scale of nanoparticles. In this paper we represent the synthesis of silver nanoparticles (AgNPs) from room dried leaves of Vinca rosea. The AgNPs were characterized by UV-vis spectroscopy. The AgNPs are crystalline in nature, were determined from scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX), X-ray diffraction patterns (XRD), and also the size of the NPs was calculated by using Hariba Nanoparticle analyzer and the stability was calculated by using the Zetapotential. The nanoparticles obtained from leaf extracts were of size 27±2 and 30±2 respectively and Zetapotential of AgNPs was found to be -63.1 mV, so it indicates the dispersion and stability. The synthesized AgNPs have very good antimicrobial activity.

Copper(II) and nickel(II) complexes of benzyloxybenzaldehyde-4-phenyl-3-thiosemicarbazone: Synthesis, characterization and biological activity

Benzyloxybenzaldehyde-4-phenyl-3-thiosemicarbazone ligand (L) has been synthesized from benzyloxybenzaldehyde and 4-phenyl-3-thiosemicarbazide. Complexes of this ligand with chlorides of Cu(II) and Ni(II) have been prepared. The structure of the ligand (L) is proposed based on elemental analysis, IR and (1)H NMR spectra. Its complexes with Cu(II) and Ni(II) ions are characterized from the studies of electronic as well as EPR spectra. On the basis of electronic and EPR studies, rhombically distorted octahedral structure has been proposed for Cu(II) complex while the Ni(II) complex has been found to acquire an octahedral structure. The ligand and their metal complexes have been tested in vitro for their biological effects. Their antibacterial activities against Gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae) and Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) have been investigated. The prepared metal complexes exhibit higher antibacterial activities than the parent ligand. The in vitro antioxidant activity of free ligand and its metal(II) complexes have also been investigated and the results however reveal that the ligand exhibits greater antioxidant activity than its complexes.

Development of an extractive spectrophotometric method for the determination of copper(II) in leafy vegetable and pharmaceutical samples using pyridoxal-4-phenyl-3-thiosemicarbazone (PPT).

A highly sensitive extractive spectrophotometric method has been developed for the determination of copper(II) using pyridoxal-4-phenyl-3-thiosemicarbazone(PPT) as an analytical reagent. The PPT forms reddish brown species of copper(II) at a pH range of 3.0-5.5, and the complex was extracted into n-butanol. The Cu(II)-PPT complex shows maximum absorbance at 440 nm, with molar absorptivity and Sandells sensitivity being 2.16 x 10(4) L mol(-1) cm(-1) and 2.94 x 10(-3) microg cm(-2), respectively. The system obeys Beers law in the range of 0.2-5.0 mg/L. The regression coefficient of the Beers law straight line is 0.338, and the correlation coefficient is 0.96. The detection limit of the method is 0.0065 microg mL(-1). Most of the common metal ions generally found associated with copper do not interfere. The repeatability of the method was checked by finding the relative standard deviation. The developed method has been successfully employed for the determination of copper(II) in leafy vegetable and pharmaceutical samples. The method is evaluated by analyzing samples from the Bureau of Analyzed Samples (BCS 233, 266, 216/1, 207, and 179) and by intercomparison of experimental values using AAS.

Synthesis and spectroscopic characterization of 3,4-difluoroacetophenone-thiosemicarbazone and its palladium(II) complex: evaluation of antimicrobial and antitumour activity.

A new cis-palladium(II)diaqua(3,4-difluoroacetophenonethiosemicarbazone complex (Pd(II) complex) is synthesized using 3,4-difluoroacetophenonethiosemicarbazone(L). The L and its Pd(II) complex are characterized and confirmed by elemental analyses, electrochemical analyses, FT-IR, FT-Raman, UV-Vis, HRMS and LC-MS techniques. Ligand L is further characterized by (1)H, (13)C and (19)F NMR spectroscopy. The crystal structure of L is unambiguously characterized by single X-ray crystallography. The ligand (L) belongs to monoclinic system with P2(1)/C space group and the unit cell parameters are a(Å)=9.1144(7), b(Å)=13.7928(7), c(Å)=8.4174(5), α(°)=90, β(°)=100.715, γ(°)=90 and volume V(A(3))=1039.73(11). The Raman bands observed for the L and its Pd(II) complex are in good agreement with the FT-IR spectral data. The Pd(II) complex is found to be highly efficient in inhibiting the growth of human pathogens like Salmonella typhimurium and Klebsiella pneumonia with MIC value 10.0μg/mL whose inhibition zones are almost comparable with the standard antibiotic. The synthesized compounds have shown antiproliferative activity against the human breast cancer cell lines MDA-MB231 by intermitting the regular pathway of ribonucleotidereductase.

Synthesis, spectral characterization and biological activities of Mn(II) and Co(II) complexes with benzyloxybenzaldehyde-4-phenyl-3-thiosemicarbazone

Mn(II) and Co(II) complexes of benzyloxybenzaldehyde-4-phenyl-3-thiosemicarbazone have been synthesized and characterized by the investigations of electronic and EPR spectra and X-ray diffraction. Based on the spectral studies, an octahedral geometry is assigned for the Mn(II) and Co(II) complexes. X-ray powder diffraction studies reveal that Mn(II) and Co(II) complexes have triclinic crystal lattices. The unit cell parameters of the Mn(II) complex are a=11.0469 Å, b=6.2096 Å, c=7.4145 Å, α=90.646°, β=95.127°, γ=104.776°, V=489.7 Å(3) and those of Co(II) complex are a=9.3236 Å, b=10.2410 Å, c=7.8326 Å, α=90.694°, β=99.694°, γ=100.476°, V=724.2 Å(3). When the free ligand and its metal complexes are subjected to antibacterial activity, the metal complexes are proved to be more active than the ligand. However with regard to in vitro antioxidant activity, the ligand exhibits greater antioxidant activity than its metal(II) complexes.

Liquid‐Liquid Extraction of Tetravalent Hafnium from Acidic Chloride Solutions using Bis(2,4,4‐trimethylpentyl) Dithiophosphinic Acid (Cyanex 301)

Abstract Liquid‐liquid extraction studies of tetravalent hafnium from acidic chloride solutions have been carried out with bis(2,4,4‐trimethylpentyl) dithiophosphinic acid (Cyanex 301) as an extractant diluted in kerosene. Increase of acid concentration decreases the percentage extraction of metal. Plot of log D vs. log [HCl] gave a straight line with a negative slope of 2±0.1 indicating the exchange of two moles of hydrogen ions for every mole of Hf(IV) extractacted into the organic phase. Extraction of Hf(IV) increases with increase of extractant concentration. The plot of log D vs. log [HA] is linear with slope 2±0.1, indicating the association of two moles of extractant with the extracted metal species. The addition of sodium salts enhanced the percentage extraction of metal, and followed the order NaSCN>Na2SO4> NaNO3>NaCl. Stripping of metal from the loaded organic (LO) with HCl and H2SO4 indicated sulphuric acid as the best stripping agent. Increase of temperature increases the percentage extraction of metal indicating the process is endothermic. Regeneration and recycling capacity of Cyanex 301, extraction behavior of associated elements such as Zr(IV), Ti(IV), Al(III), Fe(III), and IR spectra of the Hf(IV)‐Cyanex 301 complex was studied.

Synergistic Extraction of Zirconium(IV) and Hafnium(IV) with 4‐Acylbis(1‐phenyl‐3‐methyl‐5‐pyrazolones) in the Presence of Neutral Organophosphorus Extractants

Abstract Various 4‐acylbis(1‐phenyl‐3‐methyl‐5‐pyrazolones), namely, 4‐adipoylbis(1‐phenyl‐3‐methyl‐5‐pyrazolone) (H2AdBP), 4‐sebacoylbis(1‐phenyl‐3‐methyl‐5‐pyrazolone) (H2SbBP) and 4‐dodecandioylbis(1‐phenyl‐3‐methyl‐5‐pyrazolone) (H2DdBP) were synthesized and examined with regard to the solvent extraction behavior of zirconium(IV) and hafnium(IV) from hydrochloric acid solutions. The results demonstrate that Zr(IV) and Hf(IV) extracted into chloroform with 4‐acylbis(1‐phenyl‐3‐methyl‐5‐pyrazolones) (H2X), as ZrO(HX)2 and HfO(HX)2, respectively. The equilibrium constants (K ex) of the extracted complexes follow an order H2SbBP>H2AdBP>H2DdBP. The synergistic extraction of Zr(IV) and Hf(IV) was also investigated with mixtures of H2SbBP and tri‐n‐butylphosphate (TBP), tri‐n‐octylphosphine oxide (TOPO), and trialkylphosphine oxide (TRPO), where the complexation strength follows the order TOPO>TRPO>TBP. The equilibrium constants of the synergistically extracted complexes have been correlated with the donor ability of the phosphoryl oxygen of the neutral organophosphorus extractants in terms of their 31P NMR chemical shifts and their basicity values (KH =nitric acid uptake constant).

Enhanced extraction and separation of zirconium(IV) and hafnium(IV) with 3-phenyl-4-benzoyl-5-isoxazolone in presence of various neutral organophosphorus extractants

Various 3-phenyl-4-aroyl-5-isoxazolones, namely, 3-phenyl-4-benzoyl-5-isoxazolone (HPBI), 3-phenyl-4-(4-fluorobenzoyl)-5-isoxazolone (HFBPI) and 3-phenyl-4-(4-toluoyl)-5-isoxazolone (HTPI) were synthesized and examined with regard to the solvent extraction behavior of Zr(IV) and Hf(IV) from hydrochloric acid solutions. The results demonstrated that Zr(IV) and Hf(IV) extracted into chloroform with 3-phenyl-4-aroyl-5-isoxazolones (HA), as ZrOA2 and HfOA2, respectively. The equilibrium constants of the extracted complexes follow an order HFBPI > HPBI > HTPI, which is in accordance with their pKa values. The synergistic extraction of Zr(IV) and Hf(IV) was also investigated with mixtures of HPBI and tri-n-octylphosphine oxide (TOPO), trialkylphosphine oxide (TRPO), and tri-n-butylphosphate (TBP), where the complexation strength follows the order TOPO > TRPO > TBP. The equilibrium constants of the synergistically extracted complexes have been correlated with the donor ability of phosphoryl oxygen of the neutral organophosphorus extractants in terms of their 31P NMR chemical shifts and their basicity values. The addition of neutral organophosphorus extractant to the metal chelate system not only enhances the extraction efficiency but also improves the selectivity between these metal ions.

Studies of zinc(II) in pharmaceutical and biological samples by extractive spectrophotometry: using pyridoxal-4-phenyl-3-thiosemicarbazone as chelating reagent

Piridoxal-4-fenil-3-tiossemicarbazona (PPT) e proposto como um novo reagente sensivel para a determinacao espectrofotometrica de zinco(II). PPT reage com zinco(II) no intervalo de pH entre 5,0 e 6,0, para formar um complexo colorido amarelo, o qual foi adequadamente extraido em n-butanol. A absorbância do complexo Zn(II)-PPT foi medida em diferentes intervalos de tempo, a 430 nm, para averiguar a estabilidade do complexo. Foi observado que o desenvolvimento da cor foi instantâneo e estavel por mais de 48 h. O sistema obedece a lei de Beer ate 6,0 µg mL-1 de zinco(II), com uma excelente linearidade em termos do valor do coeficiente de correlacao, de 0,999. A absortividade molar e sensitividade de Sandell da especie extraida e 1,6 X 104 L mol-1 cm-1 e 4,085 X 10-3 µg cm-2, respectivamente, a 430 nm. O limite de deteccao do metodo e 0,04 µg mL-1. Para avaliar a precisao do metodo, determinacoes foram efetuadas em diferentes concentracoes; o desvio padrao relativo nao excedeu 3,1%. A composicao do complexo de zinco(II) com PPT foi estudada pelos metodos de variacao continua de Job, da razao molar, metodo de Asmus e da razao da inclinacao. PPT tem sido empregado satisfatoriamente para a determinacao de zinco(II) isoladamente, ou na presenca de outros ions, normalmente associados ao zinco(II) em amostras farmaceuticas e biologicas. Varios materiais de referencia (NIST 1573, NBS 1572 e NIST SRM 8435) tem sido testados para a determinacao de zinco, com o proposito de avaliar a exatidao do presente metodo. Os resultados do metodo proposto sao concordantes com os obtidos por espectrometria de absorcao atomica com chama.