P NMR study of the stoichiometry, stability and thermodynamics of complex formation between palladium(II) acetate and bis(diphenylphosphino)ferrocene

The complexation reaction between palladium (II) acetate, and 1,1′-bis(diphenylphosphino)ferrocene, DPPF, was investigated in two different deuterated solvents CDCl₃ and DMSO at various temperatures using ³¹P NMR spectroscopy. The exchange between free and complexed DPPF is slow on the NMR time scale and consequently, two ³¹P NMR signals were observed. At metal ion-to-ligand mole ratio larger than 1, only one ³¹P NMR signal was observed, indicating the formation of a 1:1 Pd²⁺–DPPF complex in solution. The formation constant of the resulting 1:1 complexes was determined from the integration of two ³¹P signals. The values of the thermodynamic parameters (ΔH, ΔS and ΔG₂₉₈) for complexation were determined from the temperature dependence of stability constants. It was found that, in both solvents, the resulting complex is mainly entirely enthalpy stabilized and the ΔH compensates the TΔS contribution.     

Multiple Spectroscopic,Docking and Cytotoxic Study of a Synthesized 2,2′ Bipyridin Phenyl Isopentylglycin Pt(II) Nitrate Complex: Human Serum Albumin and Breast Cancer Cell Line of MDA-MB231 as Targets

In the present study, the biological activities of a new synthesized Pt(II)-complex, 2,2′ bipyridinphenyl isopentylglycin Pt(II) nitrate was investigated via its interaction with the most important blood carrier protein of human serum albumin (HSA), using fluorescence and Far-UV circular dichroism (CD) spectroscopic techniques and also molecular docking. Moreover, cytotoxicity activity of the complex was studied against breast cancer cell line of MDA MB231 using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The Pt(II)-complex has a strong ability to quench the intrinsic fluorescence of HSA through a static quenching mechanism. According fluorescence quenching data, the binding parameters of the interaction were calculated and showed that hydrophobic interaction has an important role. The molecular docking results in coherent with fluorescence measurements illustrated that Pt(II) complex can bind to HSA at one position that located in the hydrophobic cavity of groove between drug site I and II. Also, experimental data on driving force in binding site was confirmed whereas theoretical results demonstrated Pt(II) complexinteract to HSA by hydrophobic interaction. Far-UV-CD results showed that Pt(II)-complex induced an increasing in the content of α-helical structure of the protein and stabilized it. Also, MTT assay represented growth inhibitory effect of the complex toward the breast cancer cell line.     

Kinetics of complex formation between palladium(II) acetate and bis(diphenylphosphino)ferrocene

The kinetics of complex formation between palladium(II) acetate, and 1,1’-bis(diphenylphosphino)ferrocene, dppf, in two different deuterated solvents CDCl₃ and DMSO-d₆ were investigated using ³¹P NMR spectroscopy. The mole ratio and the ³¹P-chemical shifts in DMSO-d₆ solution revealed the formation of an intermediate, which is gradually converted into the more stable [Pd(dppf)OAc)₂] species with a dppf acting as a chelate ligand. In the chloroform solution however, the interaction of metal ion and the ligand resulted directly in the formation of [Pd(dppf)OAc)₂] species with a chelating dppf. The rate constant for the complexation reaction was evaluated from computer fitting of the corresponding integration-time data.     

Using KKM technique in set-valued optimization problems and variational-like inequalities

KKM technique has proved a very useful tool in many areas of analysis. This paper aims to use this technique to give some necessary and sufficient conditions for set-valued optimization problems. We also use the KKM technique to introduce sufficient conditions for solution existence of some kinds of variational-like inequalities and thereby setvalued optimization problems.     

Catalyst‐Free and Green Synthesis of Some Novel Benzamide Derivatives

In the present work, a simple, green, rapid, and catalyst‐free procedure for the synthesis of benzamide derivatives by ring opening of azlactones with diamines such as ethylene diamine and 1,3‐propylenediamine is described. The present method offers several advantages such as short reaction times, easy work‐up, and mild reaction conditions in the absence of catalyst and any toxic solvent and material. In addition, the structure obtained by X‐ray crystallography was compared with the theoretical results obtained by density functional theory using the B3LYP functional and cc‐pVDZ basis sets.     

Amine-catalyzed preparation of oxygenated derivatives of symmetric trisulfides

Bipyridinium tribromide reacts with thiols in the presence of thionyl chloride to yield symmetric trisulfide derivatives (RSS(O)SR) as the major products. Two possible mechanisms are advanced to explain the chemistry.     

Preparation and Electrochemical Characterization of an Enzyme Electrode Based on Catalase Immobilized onto a Multiwall Carbon Nanotube‐Thionine Film

The present study was aimed at investigating the use of a mixture multiwall carbon nanotube (MWCNT) and thionine (Th) dye in designing of a thionine‐based electrochemical biosensor containing catalase (Ct) enzyme (MWCNT‐Nafion‐Th/Ct) onto a glassy carbon electrode (GCE). The effects of pH, MWCNT concentration and thionine concentration on electrochemical response were explored for optimum analytical performance. The modified electrode exhibited a pair of well‐defined, quasi‐reversible peaks at formal potential (E^o′) = ‐0.218 ± 0.017 V vs. Ag/AgCl corresponding to the Th_ox/Th_red redox couples in the presence of MWCNT, Nafion, and Ct. The electrochemical parameters, including charge‐transfer coefficient (0.36), and apparent heterogeneous electron transfer rate constant (4.28 ± 0.26 s^?1) were determined. Using differential pulse voltammetry, the prepared enzyme electrode exhibited a linear response to hydrogen peroxide (H₂O₂) in the range of 10.0‐100.0 μM with a detection limit 8.7 μM and a sensitivity of 6051.0 μA mM^?1 cm^?2.