Sharif Digital Repository

Using field assisted dissociation model and with a classic view the dissociation probability is calculated when it a molecule is exposed with a Ti:sapphire laser with wavenumber of 800nm and the energy of . using gradient optimization method we find a tailored two rectangular laser pulse for controlling the dissociation of C-H bond of . Using classical method reduced the complicacy of solving schrodinger equation. In our optimization method in contrast with the usual controlling method experimental data is not needed and this reduced the controlling costs.

 

In this project rotational barrier around the C-N bond in 4-ethyle-morpholine- carboxylate has been studied using DNMR spectroscopy. Spectra were taken at variable temperature, and then with simulation of bandshape broadening pattern at coalescence region, rate constants of exchange were obtained for all temperatures. For simulation of line-shape broadening Spinworks software was used, that with two interfaces made possible simulation with two bandshape simulator programs, DNMR and MEXICO. The rate constants obtained from simulations, were used for calculation of thermodynamic activation parameters (∆G#, ∆H#, ∆S# and Ea). ∆G# 298 value of 13.66 Kcal/mol for 4-ethyle-morpholine- carboxylate... 

We have reported a new and efficient synthesis of a broad spectrum of heterotetracyclic benzoxazocines via unique tandem 1,3-dinucleophilic addition of different bifunctional nucleophiles to quinolinium and isoquinolinium salts. The reaction generally involves the initial addition of nucleophiles to quinolinium salts to form enamine intermediate which can be trapped by intramolecular O/S-alkylation of nucleophiles. This protocol is a very mild and simple method for construction of eight-membered ring in fused heterocycles in a one-step process. We have also developed an efficient asymmetric synthesis of α,β-disubstituted γ-bisalkoxycarbonyl and α, β- disubstituted γ- phosphono sulfonates via... 

The Barrier of the internal rotation around C-N bond in O-ethyle morpholine-4-carbotioate were calculated using dynamic NMR spectroscopy (DNMR) in DMSO solvent. 1H and 13C NMR spectra were recorded at different temperatures (295-350K). Band shape broadening patterns at coalescence regions were simulated to extract rate constants of NMR spectera. Transition state thermodynamic properties of internal rotation around C-N bond in O- ethyle morpholine -4- carbotioate are estimated: , , , . To assay reliability of the estimated values, transition state thermodynamic properties were calculated using PCM model at method and basis set B3LYP/6-311++G(d,p). Theoretical values of thermodynamic... 

Computational chemistry is used to study solvent and substituent effects on kinetics and mechanism of some organic reactions. It also is used to study enzyme reactions and enzyme structures. Organic reactions were studied by ab initio quantum mechanics and Monte Carlo simulations. The enzyme studies were done by QM/MM and MD methods in Lund University. The studied organic reactions are 1) Reactions of hydroxylamine and aminoxide anion with methyl iodide. 2) Rearrangement of allyl p-tolyl ether. 3) Reactions of 1,4-Benzoquinone with Cyclopentadiene and Cyclohexadiene derivatives and reaction of cyclopentadiene and vinyl acetate. In the enzyme studies the catalytic reaction of Glyoxalase... 

In this study, electrochemical oxygen reduction reaction (ORR) was studied on Cu, Pd, Rh, Pd-Cu and Rh-Cu alloys in alkaline solution. Pd-Cu and Rh-Cu alloys were prepared by electrochemical methods. On copper electrode it is found that direct oxygen reduction is accompanied by the electrochemical reductions of copper oxides. Also, mechanism and kinetics of reaction change as the amount of copper oxides increase on the surface. For electrodeposited alloys, it is indicated that the reactivity of Pd-Cu and Rh-Cu alloys toward oxygen reduction is higher than pure Pd and pure Rh. The maximum reactivity among Pd-Cu alloys is related to the sample with 24.5% copper content while the maximum... 

A Reaction Wheel (RW) is a torque actuator which is used for attitude control of a satellite. Reaction Wheels usually consist of a brushless DC motor which rotates a flywheel. When the flywheel is accelerated by the motor, the reaction torque of the motor applies to the base of the RW and therefore the satellite can rotate along the RW spin axis. Due to frictionless surrounding of a satellite in space, a very small disturbance in a reaction wheel structure during its function may lead to instability of satellite and decrease the satellite precision and performance. There are some important sources of disturbance in an RW. Some of them are: 1- Unbalances in wheel (offset of center of gravity... 

In this project rotational barrier around the C-N bond in Ethyl N-(pipyridin carbotioate) has been studied by using DNMR spectroscopy. Spectra were taken at various temperatures , and then with simulation of bandshape broadening pattern at coalescence region, the exchange rate constant of were obtained for all temperatures. For simulation of line-shpe broadening Spinworks software was used, that with two interfaces made possible simulation with two bandshape simulator programs, DNMR and MEXICO. The rate constants obtained from the simulation were used for calculation of thermodynamic activation parameters (... 

In this project rotational barrier of C-N bond in Ethyl N-(pyrrolidine carbotioate) has been studied using DNMR spectroscopy. Spectra were taken at various temperatures, and then with simulation of bandshape broadening pattern, rate constants of exchanges were obtained for all temperatures. For simulation of line-shape broadening SpinWorks software was used,which with two interfaces made possible simulation with two bandshape simulator programs, DNMR and MEXICO. The rate constants obtained from simulations, were used for calculation of thermodynamic activation parameters (?G#, ?H#, ?S# and Ea#).Experimental ?G# 298value(Experimental) of 18.3 Kcal/mol for Ethyl N-(pyrrolidine... 

In the first chapter, three efficient synthesis of novel polyheterocyclic indole and thiochromone-annulated thiopyranocoumarin derivatives are achieved via domino Knoevenagel hetero Diels–Alder reaction of O-acrylated and O-propargylated salicylaldehyde derivatives with indolin-2-thiones and 4-hydroxy dithiocoumarin. The domino Knoevenagel-hetero-Diels–Alder reactions are very efficient process that allows the formation of two or more rings at once, avoiding sequential chemical transformations. The products are formed in good-to-excellent yields with high regio- and stereoselectivity. The major advantage of this reaction is the ease of the work-up during which the products can be isolated... 

In this study, a catalyst-free Mannich reaction is applied for synthesis of 1,3-oxazines as an important class of biologically active compounds. In order to consider environmental application a mixture of water and ethanol is selected as a solvent for the reaction of 2,7-dihydroxynaphthalene with formaldehyde and an amine. Primary consideration of substitution effect on the reaction revealed that aniline and its derivatives with electron-donating substituent and halogens, cause higher yield. Aliphatic amines are not good substrate for this reaction with the exception of benzyl amine  

Alloy coating of nickel - molybdenum with 20-25 wt% Mo, exhibits excellent protective properties against corrosion in different corrosive environments, therefore it has received much attention. In comparison with Ni coatings, Ni-Mo coatings reduce hydrogen evolution reaction overpotential(HER) significantly, therefore it has suitable catalytic properties for HER.
A few researches on pulse reverse palting of Ni-Mo coatings have been published. in this work, we have evaluated effects of PRC on some properties of Ni-Mo coating such as chemical composition, morphology, catalytic properties for HER, crystaline structure and hardness property. The results of atomic absorption spectroscopy(AAS)... 

In this project, rotational barrier of C-N bond in thiobencarb (S-alkyl thiocarbamate) has been studied by HNMR spectroscopy. All the spectra were taken at different temperatures, and then by simulation of bandshape broadening pattern, rate constants for all temperatures were calculated. SpinWorks software was used for the simulation of line shape broadening which has two bandshape simulator programs, DNMR and MEXICO. The obtained rate constants were used to calculate the thermodynamic parameters of activation (ΔG‡, ΔH‡, ΔS‡ and Ea). Experimental ΔG‡298 value for thiobencarb was calculated 15.11kcalmol-1 and 15.86 kCalmol-1 in chloroform and acetone solvents respectively. The computational... 

We have reported a new and efficient synthesis of a broad spectrum of heterotetracyclic benzoxazocines via unique tandem 1,3-dinucleophilic addition of different bifunctional nucleophiles to quinolinium and isoquinolinium salts. The reaction generally involves the initial addition of nucleophiles to quinolinium salts to form enamine intermediate which can be trapped by intramolecular O/S-alkylation of nucleophiles. In the third part, as continues, we have reported another method which consists of Anthocyanidins and Thioindoles by using water and acetic acid as the solvent. This protocol is a very mild and simple method for construction of eight-membered ring in fused heterocycles in a... 

A novel reduced mechanism is introduced which aimed to predicts NOx and CO generation in advanced industrial gas turbine combustors. The survey is initially conducted by considering 25 species in GRI-3 mechanism of Methane oxidation and continued to choose nine of the most important species based on the quasi-steady state analysis. Finally, a new skeletal reduced mechanism with 35 reactions and 20 species is derived using sensitivity analysis, reaction path analysis, and some physical reasons. The overall validity of this mechanism is clearly confirmed by comparing the present predicted results with GRI-3 full mechanism in a PSR reactor. The adiabatic flame temperature and all of the main... 

The current study deals with application of a surfactant-like Brønsted acidic ionic liquid (IL) 1-dodecyl-3-methylimidazolium hydrogensulfate (catalys 1) for Mannich reaction at room temperature. The reaction has been efficiently proceeds in water as solvent without using any harmful and expensive organic additives. Our observation has been shown that the reaction is selective for cyclohexanone and no product was observed by using cyclopentanone at room temperature. Density functional theory (DFT) calculations were performed to provide evidence about the nature of reactivity of the cyclohexanone/cyclopentanone. The activity of the catalyst 2 (1-dodecyl-2,3-dimethylimidazolium... 

In this research,Graphene Oxide nanoplatelets (GO) were synthesized by chemically modified Hummer's method.After the GO nanosheets electrochemically reduced to graphene, nanoparticles imposed to this thin film.This optimized nanostructure coating was utilized for investigating the Hydrogen Evolution Reaction (HER) over the copper substrate. In order to optimize the kinetic of electrodeposition and reduction, diverse electrochemical approaches such as cyclic voltammetry, chronoamperometic and potentiometric as well as pulse electrodeposition methods were employed. Electrochemical procedures were aligned by Design of Experiment (DOE) ... 

In modeling of biological systems and chemical reaction networks, analy-sis the existence of multiple equilibria is important. Our interest in using dynamical system in such analyses comes from biology. So, we will study the qualitative properties of a dynamical system, described by a system of ordinary differential equations. In this thesis we will discuss the question of how to decide when a general chemical reaction system is incapable of admitting multiple euilibria, regardless of parameter values such as reaction rate constants. We will relate different graphs to chemical reaction systems, and by means of its paths and circuits, we will introduce some sufficient conditions for... 

Improving the photocatalytic activity of titania nanoparticles and Cognition the mechanisms governing this property, has received more attention in the recent few years. One of the main strategies for improving the photocatalytic activity and modifying the bandgap structure of titania nanoparticles, is incorporation different metallic and nonmetallic ions in the titania lattice. In this study, 1%Fe, 1%Gd and 2%P (molar ratio) doped titania nanoparticles were successfully prepared by a modified sol-gel method in room temperature. The products were characterized with various spectroscopic and analytical techniques to determine their structural, morphological, physicochemical and... 

Cadmium sulfide (CdS) thin films were successfully fabricated in argon atmosphere on glass slides and Single Layer Graphene(SLG)/Cu foil stack by close space sublimation technique in three different deposition temperatures. Successive Ionic Layer Adsorption and Reaction (SILAR) technique is used as a complementary technique for better and denser layers. Analysis techniques such as Grazing Incident X-ray Diffraction (GIXRD) and Scanning Electron Microscope images were used for structural study of the deposited layers. Polycrystallinity and hexagonal wurtzite structure of the thin films is confirmed. For band gap calculations and for determination of optical behavior of the layers in different...