New metal compounds and their reactivity towards bovine milk casein

The l,2-bis(sulphapyridyl)oxamide ligand [L] and its complexes with Fe^III, Co^II, Cu^II and Zn^II chloride were synthesized and characterized by elemental analyses, i.r., n.m.r., e.p.r. and u.v.–vis. spectroscopy and molar conductance measurements. Spectroscopic studies show that all the complexes are octahedral and covalent. The electrochemical behaviour of the Co^II complex was monitored by cyclic voltammetry in a buffer/DMF solution (95:5). The E ⁰ values –0.622 and –0.502 V reveal a reversible one electron redox wave attributed to a Co^II/Co^I redox couple at a scan rate of 0.1 V s^–1. The interaction of the Co^II complex with bovine milk casein (BMC) was studied at the same scan rate, which reveals a strong binding as the E ⁰ values shift to more negative potential (E ⁰ = –0.908 and –0.703 V). The cyclic voltammograms of the Co^II complex bound by BMC were recorded at different pH's. The plot of E ⁰ versus pH showed that E ⁰ values are maximal at pH 7.4 indicating good interaction between the BMC and the Co^II complex which is further confirmed by kinetic data. The kinetic studies of the Co^II complex bound to BMC was monitored in phosphate buffer solution at different pH's by spectrophotometry. The absorbance changes were monitored at 278 nm ( _max for BMC) with respect to time and pseudo-first-order rate constants, K _obs, were obtained from the slope and intercept of the straight line using the least squares regression method. The plot of absorbance versus time at different pH's was linear up to 80% completion of the reaction. The pH-rate profile data reveals that the reactions are pH dependent.     

Synthesis and characterization of new synthetic oxygen carriers. A kinetic study of the reaction of the binuclear iron(III)–copper(II) complex with H<Subscript>2</Subscript>O<Subscript>2</Subscript>

New oxygen carriers have been synthesized by the interaction of the Cu^II/Ni^II derivative of the bis(5-nitroindazolyl)methane complex with 14-membered 1,8-dihydro-1,3,6,8,10,13-hexaazacyclotetradecane (M-mac), where M=Fe^III, Ni^II, Co^II, to yield binuclear complexes. These complexes have been characterized by physico-chemical methods: elemental analysis, i.r., ¹H-n.m.r., ¹³C-n.m.r., 2D cosy n.m.r., e.p.r., u.v.–vis. spectroscopy and cyclic voltammetry. A representative binuclear Fe^III–Cu^II complex was chosen to interact with H₂O₂ to elucidate the mechanistic pathway of oxygen binding in solution spectrophotometrically, and also by cyclic voltammetry. Hydrogen peroxide exhibits two mechanisms for binding, either (i) homolysis or (ii) heterolytic cleavage. The mode of H₂O₂ binding can be hazardous in (i) due to the threat of oxidative damage to the cellular structure, proteins and metabolites, or eco-friendly as in (ii) which produces innocuous products such as water and dioxygen. This study aims to combat the problems associated with H₂O₂ binding in nature by producing a parallel study on model compounds.     

Chemical composition and medicinal significance of Fagonia cretica: a review

Members of the family Zygophyllaceae are distributed in arid areas of the world and are traditionally used against various health insults ranging from skin lesions to lethal cancer. Fagonia cretica Linn. is a plant having novel compounds responsive in diseases that are still considered as incurable or are curable with serious side effects. Researchers, particularly of the Asian region elaborately studied the chemical composition and pharmacological activities of this plant. But further studies are still required to evaluate this plant in clinical trials in order to save humanity from synthetic chemical drugs yet disputed as ‘friends or foe’.     

Synthesis and structures of copper complexes bearing unsymmetric derivatives of (R,R)‐1,2‐diaminocyclohexane: An efficient catalyst for asymmetric Henry reaction

A series of Cu (II) complexes bearing asymmetric derivatives of (R,R)‐1,2‐diaminocyclohexane were synthesised and characterised. The X‐ray structures of the complexes showed distorted square planar geometry. The catalytic activities of in situ‐generated copper acetate complexes in the presence of 10 mol% of N,N‐diisopropylethylamine were evaluated in the asymmetric Henry reaction. The current catalysts showed high enantioselectivity (up to 99%) for (S)‐1‐nitro‐4‐phenylbutan‐2‐ol from the reaction of 3‐phenylpropanal and nitromethane.     

Synthesis of optically active bromophenol blue encapsulated mesoporous silica–titania nanomatrix: structural and sensing characteristics

Journal of Sol-Gel Science and Technology - Mesostructured silica-titania (ST) and bromophenol blue encapsulated silica–titania (BPB-ST) nanomatrices are synthesized by sol–gel method...     

Adsorption and Kinetics Studies of Cr (VI) by Graphene Oxide and Reduced Graphene Oxide-Zinc Oxide Nanocomposite

In this work, graphene oxide (GO) and its reduced graphene oxide-zinc oxide nanocomposite (rGO-ZnO) was used for the removal of Cr (VI) from aqueous medium. By employing a variety of characterization techniques, morphological and structural properties of the adsorbents were determined. The adsorption study was done by varying concentration, temperature, pH, time, and amount of adsorbent. The results obtained confirmed that rGO-ZnO is a more economical and promising adsorbent for removing Cr (VI) as compared to GO. Kinetic study was also performed, which suggested that sorption of Cr (VI) follows the pseudo-first-order model. For equilibrium study, non-linear Langmuir was found a better fitted model than its linearized form. The maximum adsorption capacity calculated for GO and rGO-ZnO nanocomposite were 19.49 mg/g and 25.45 mg/g, respectively. Endothermic and spontaneous nature of adsorption was detected with positive values of ΔS (change in entropy), which reflects the structural changes happening at the liquid/solid interface.     

Insights into the Protective Effects of Thymoquinone against Toxicities Induced by Chemotherapeutic Agents

The drugs used to treat cancer not only kill fast-growing cancer cells, but also kill or slow the growth of healthy cells, causing systemic toxicities that lead to altered functioning of normal cells. Most chemotherapeutic agents have serious toxicities associated with their use, necessitating extreme caution and attention. There is a growing interest in herbal remedies because of their pharmacological activities, minimal side effects, and low cost. Thymoquinone, a major component of the volatile oil of Nigella sativa Linn, also known as black cumin or black seeds, is commonly used in Middle Eastern countries as a condiment. It is also utilized for medicinal purposes and possesses antidiabetic, anti-cancer, anti-inflammatory, hepatoprotective, anti-microbial, immunomodulatory, and antioxidant properties. This review attempts to compile the published literature demonstrating thymoquinone’s protective effect against chemotherapeutic drug-induced toxicities.     

Synthesis,characterization, electrochemistry and kinetics of CTDNA binding of a bis ciprofloxacin borate copper(II) complex

A new boroderivative of ciprofloxacin and its Cu^II complex has been synthesized and characterized by elemental analysis, i.r., e.p.r., u.v.–vis., n.m.r. spectroscopy. Molar conductance measurements show that the complex is ionic. E.p.r. values and electronic spectral data suggest that it possesses square planar geometry. The reaction kinetics of the ligand K[C₃₄H₃₆N₆O₆F₂B] and its Cu^II complex with calf thymus DNA (CTDNA) has been monitored spectrophotometrically in aqueous media. The K _obs value has been calculated under pseudo-first order conditions and it has been observed that the Cu^II complex is a more efficient DNA inhibitor than the free borate of ciprofloxacin. The redox behavior of the Cu^II complex in the presence and in the absence of CTDNA in aqueous solution has been investigated by cyclic voltammetry. The cyclic voltammogram of the Cu^II complex exhibits one quasireversible redox wave for a one-electron transfer corresponding to Cu^II/Cu^I redox couple with E _1/2 values –0.613 and –0.649 V respectively. On interaction with CTDNA, the Cu^II complex exhibits a shift in E _1/2 values corresponding to 0.013 and 0.035 V respectively.     

Oxidative Cleavage of Oximes with Silica‐Gel‐Supported Chromic Acid in Nonaqueous Media

A simple procedure for a clean and high‐yielding oxidative deoximation of benzaldoximes and ketoximes using a silica‐gel‐supported chromic acid reagent has been developed. This solid‐supported reagent allows us to carry out this reaction in nonaqueous dichloromethane reaction media.