Sharif Digital Repository

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... 

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... 

Prediction and calculation of shielding tensors of H, C, F and P nuclei of different molecules has been the subject of much research, because these nuclei have the greatest importance in NMR experiments. The optimum wave functions and calculation method were obtained using empirical models and factorial design. Based on preliminary experiences, the following four factors at two levels were selected: electron correlation, triple-ξ valence shell, diffuse function and polarization function. The wave functions for calculating gas phase 1H and 13C chemical shifts of various types of alcohols, amines and simple hydrocarbons were optimized using empirical model. The B3LYP/6-311+G wave function is... 

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 this work we have studied conformation of ranitidine by dynamic nuclear magnetic resonance spectroscopy (DNMR) in four different solvents: chloroform, acetone, dimethylsulfoxide, and deuteriumoxide. Ranitidine has three tatumeric forms of enamine, nitoic acid, and imine, but its stable structure is enamine. Temperature dependent 1HNMR spectra of ranitidine which reportet at 500MHz were consistent with the following free activation of energies ΔG# (kcal mol-1): chloroform = 16.2; acetone = 15.4; dimethylsulfoxide = 15.1. The experimental results were confirmed by DFT theoretical calculations at the B3LYP/6-311++G (d, p) level of theory. It was also proved that ranitidine has the form of... 

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... 

In this research, the barrier around C-N bond in the molecule of 2-cyano ethyl morpholine-4-carbo dithioate was calculated by dynamic NMR. The 1H-NMR spectra of sample were recorded between temperatures of 240-332 K and 240-328 K in chloroform and acetone solvents, respectively. By analyzing the spectra by SpinWorks software, thermodynamic parameters (ΔG# , ΔH# , ΔS# ) extracded and compared with the data of quantum calculations . In quantum calculations, we compared data in two level (HF and B3LYP ).Consequently, the data of B3LYP method was better .Experimental ΔG# for internal rotation around C-N bond in 2-cyano ethyl morpholine-4-carbo dithioate was 14.04 kcal mol -1 and compared to... 

In this project the energy of rotational barrier of C-N bond in 2-cyanoethyl piperidine-1-carbodithioate has been studied by using Dynamic Nuclear Magnetic Resonance spectroscopy. Spectra were taken at various temperatures in two different solvent; acetone and chloroform. For simulation of line-shape broadening SpinWorks software was used. This with two interfaces made possible simulation with two band-shape simulator programs; DNMR and MEXICO. The rate constants obtained from simulations were used for calculation of thermodynamic activation parameters (ΔG#. ΔH#. ΔS# and Ea#). The computational calculations were done by using Gaussian03 in several level and basis sets that are in good... 

In this project, the behavior of single strand DNA (ssDNA) that is end-tethred to surface (surface is covered with an layer of mercaptohexane ) through the Monte Carlo simulation has been investigated. To understand this behavior, a ssDNA has been studied through freely jointed chain (FJC) model with electrostatic, base paring, and base-pair stacking interaction. The concentration of sodium chloride salt in solution is 1 mM and the applied surface potential is -1.5 - +0.25 V. Computational results show that the ssDNA chain can have the following configurations: 1) “very closed”, 2) “closed”, and 3) “open” that considering the amount of energy, the mentioned configurations can be compared... 

These days, self-assembly is one of the most significant phenomena in chemistry and biology. Although There are some Experiments and Simulations which help us to understand self-assembly much more than before, their mechanism is poorly understood. As a result, Calculating Free-energy landscape could be a great development in this area.We use the Flat-histogram monte Carlo algorithm to calculate the density of states of a complex system. In this way, there is a comparison between the exact density of states of Ising Model and the same quantities that are obtained from Flat histogram Method. After that, there would be a combination of statistical thermodynamics and Graph theory toward drawing... 

In this project, 13 C nuclear magnetic shielding constants and also hindered internal rotation about C-N bond in compound 4 -(phenylacetyle) morpholine are investigated The Factorial Design method was used to obtain the best solution for chemical shift computations and comparison made out in two levels (HF and B 3 LYP). Consequently the (B 3 LYP) method own better data. 13 C NMR 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... 

NMR spectroscopy as a powerful technique is often used to investigate on structural and conformational studies on proteins and drug compounds. In this work, conformations and structural properties of drug compounds and some nucleoside derivations have been studied using advanced NMR techniques including H-H COSY, HMQC, HMBC and NOESY and quantum based calculations.Experimental analysis on Valsartan show that there are two simultaneous conformers (M and m) with unequal population in M-m type solvents and two stable conformers (N and n) in the N-n type solvents. As the results show, different intramolecular hydrogen bond is the reason for stability af all available conformers. In the... 

In this project rotational barrier of C-N bond in 2-Cyanoethyl-Pyrrolidine-1-Carbodithioate 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 (ΔG#, ΔH#, ΔS# and Ea#). Experimental ΔG# value of 18.4 Kcal mol-1 for 2-Cyanoethyl-Pyrrolidine-1-Carboditioate in... 

In this work, we establish the constancy of expansion ratio (density factor) and adiabatic flame temperature for predicting lower explosive limits and further establish the constancy of expansion ratio for measuring upper explosion limits. Flammability limits are important characteristics of combustion processes. The flame can only propagate in a specific range of ratios of concentration of fuel to oxidant. The maximum of this concentration ratio that make possible propagation of flame in a mixture, is called upper flammability limit. The minimum of this ratio that make flame propagation possible is called lower flammability limit. Limits of flammability change with initial conditions such... 

Although CO2 is an environmentally benign solvent, many organic solutes are only sparingly soluble in CO2. We use Monte Carlo simulations in the context of statistical perturbation theory, Widom’s particle insertion and expanded ensemble techniques in order to investigate the molecular properties involved in enhancing the solubility of materials in CO2. Our Monte Carlo simulation of diluted methane and its fluorinated forms showed that substitution of H atom with F atom, results in more favorable solvation, but with further increase of F atom (after CH2F2) due to small size of solute it is impossible for all CO2 molecules in the first solvation shell (FSS) to have a good orientation against... 

In this project, investigation of C-N internal rotation in ethyl tetrahydro-1(2H)-pyridine carbdithioate and ethyl 1-pyrrolidine carbodithioate were investigated by dynamic nuclear magnetic resonance spectroscopy. The 1HNMR and 13CNMR spectra were taken at the variable tempratures around the coalescence temprature. Thermodynamic parameters were calculated by analysing the spectra and the outcomes were compared by the theoretical results. For ethyl tetrahydro-1(2H)-pyridine carbdithioate ∆G‡ was 14.3 (kcal/mol) and for ethyl 1-pyrrolidine carbodithioate ∆G‡ was 17.0 (kcal/mol) which were in accordance with the theoretical results. The analysis were done by the Spinworks program which... 

Carbon dioxide is one of the most significant greenhouse gases in biocycle. This gas makes the equilibrium temperature by absorbing IR radiations on the earth. It is the reason that prevent the earth from freezing. Increasing CO2 emissions in atmosphere, makes problems such as global warming. According to the Kyoto Protocol, all the countries attended to this protocol, must decrease greenhouse gases emissions. Although H2 fuel is one of the best alternative fuel against fossil fuels, the most important industrial process (steam-methane reforming) produce CO2 as by-product. Thus, gas separation has a prominent role in industrial processes such as CO2 capture and H2 purification.Today, gas... 

Members of Centaurea species are common traditional medicines throughout the world. For this reason medicinal plants are the targets of intense Phytochemical studies. In this research we have investigated Centautea Golestanica which are members of this genus and endemic of Iran. In this research, One Flavonoid, two Sesquiterpenelactones and two triterpenoides were elucidated by advanced spectroscopic techniques such as IR, MS, 1H NMR, 13C NMR and 2D NMR. In continuation of this research, we have reported new and efficient methods for the synthesis of hitherto unknown indole-annulated pentacyclic indolylhydroisoquino lines and naphthooxazocines via tandem dinucleophilic addition of... 

In this thesis, We have investigated the accuracy of general equation of state ( EoS III ) and linear isotherm regularity ( EoS I ), introduced on 2009 and 1993, respectively, and the Ghatee’s equation of state ( EoS II ) introduced on 2001, for the pvT data and thermodynamic properties of [BMIM][PF6] ionic liquid. We have carried out simulations at first in a narrow range of pressure, namely within 1-3400 atm and in temperature range from 398 K to 1000 K. The results of fitting of EoS I, EoS II and EoS III into the simulations results, leads to R2 > 0.9936, 0.9800 and 0.9949 respectively, for the pressure range of 1-3400 atm and for the temperature range of 398-1000 K. The results of...