Sharif Digital Repository

Electrocatalytic oxidation of L-ascorbic acid (L-AA) on silver electrode in alkaline solutions was studied employing cyclic voltammetry, chronoamperometry and impedance spectroscopy techniques. In comparison to Pt, the onset potential for L-AA electro-oxidation process on Ag, in a solution containg 0.02 M L-AA and 0.5 M NaOH, was 0.1 V more negative. Also, L-AA oxidation current increased more than 900% at -0.26 V/SCE. According to voltammety and impedance spectropy findings, although hydroxide anion presence was vital for L-AA oxidation to occur, at potentials more positive than -0.2 V/SCE, hydroxide ion tends to inhibit the oxidation process. Studies on the L-AA oxidation process on Ag in... 

In order to obtain more insight into the enzymatic oxygen-atom-transfer (OAT) process and elucidate the relation between the structure and function of the synthetic model complexes, new molybdenum and tungsten complexes containing different chelating ligands were systematically prepared and investigated. Herein, the cis-dioxo-molybdenum(VI) complexes with new aromatic dithiolene ligands, formulated as [MoO2(2,3ppdt)2]NR4 and [MoO2(3,4ppdt)2]NR4, (2,3ppdt= pyrido-2,3-pyrazine-2,3-dithiolato, 3,4ppdt= pyrido-3,4-pyrazine-2,3-dithiol and R= Et or Bu) were prepared and investigated by elemental analysis, IR, 1H NMR and UV-Vis spectroscopic methods. An OAT reaction of [MoO2(2,3ppdt)2]2– with PPh3... 

Self-Assembled Monolayer (SAM) is the first step in all surface engineering and assembly processes. It is used in sensor fabrication, memories and molecular recognition and optoelectronic devises as an active surface for patterning and chemical architecting of solid substrates. Tetraphenyl porphyrins because of their high stability and uniqe electronic and optic properties, that comes from their conjugate π electrons, easily can be used in these monolayers. Moreover they have a wide application because of their ability for coordination with metals and accepting substituents with electron donating and withdrawing properties. Electron transport through these layars which attach to the surface... 

Part 1: A novel modified pyrolytic graphite electrode with nanodiamond/graphite was fabricated. The electrochemical response characteristics of the modified electrode toward the epinephrine (EN) and uric acid (UA) are studied by means of cyclic and linear sweep voltammetry. The structural morphology and thickness of the film was characterized by SEM technique.The prepared electrode shows an excellent catalytic activity in the electrochemical oxidation of EN and UA, leading to remarkable enhancements in the corresponding peak currents and lowering the peak potentials. The prepared modified electrode acts as a highly sensitive sensor for simultaneous determination of EN and UA in the presence... 

One of the great challenges of food industry is the lack of packing materials which can disperse active compositions properly for variety of applications; therefore an antioxidant/antibacterial release system of poly lactic acid in a specific time is a necessity for being used in food packing industry. Most of the researches have been done in the field of drug release system, yet numbers of researches done in the field of food industry are rare. Rate of antibacterial/antioxidant release from polymeric film is relatively fast also calculated based on Fick’s second law of diffusion; therefore primary poly lactic acid is modified by adding ameliorative agents such as poly ethylene glycol and... 

Ternary copper (II) complexes having heterocyclic bases and α-amino acid salicylaldiminates
as models for the type-2 sites in copper oxidases are of great biological importance. Considerable attention has given to mixed ligand complexes due to their antitumore, antimicrobial , inflammatpry , ascorbate oxidase (AO) and dopamine β-hydroxylase(DβH) and radio- imaging properties. With this in mind, new copper (II) complexes including amino acid Schiff base and heterocyclic bases (1,10 phenanthroline and 2, 2 biprydine ) have been synthesized, investigated and characterized by IR, UV-Vis and CHN. In the case of amino acid Schiff-base complexes, the tridentate ONO Schiff base ligand...