List of Articles توتومری

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  1 - Theoretical investigation of tautomerisation of 3-Amino-1H-1,2,4-Triazol-5(4H)-One by using quantum calculations by DFT method.
  بهزاد چهکندی
  در این تحقیق بررسی توتومریزاسیون و حالت‌های گذار مولکول 3-آمینو-1H-4،2،1- تری‌آزول-5)4H (- اٌن که حاصل از انتقالات 1و3 پروتون بین اتم های اکسیژن و نیتروژن است با استفاده از محاسبات کوانتومی در سطح محاسباتیDFT-B3LYP/6-311++G(d,p)، در فاز گازی و در محیطی با حضور یک و دو م More

  در این تحقیق بررسی توتومریزاسیون و حالت‌های گذار مولکول 3-آمینو-1H-4،2،1- تری‌آزول-5)4H (- اٌن که حاصل از انتقالات 1و3 پروتون بین اتم های اکسیژن و نیتروژن است با استفاده از محاسبات کوانتومی در سطح محاسباتیDFT-B3LYP/6-311++G(d,p)، در فاز گازی و در محیطی با حضور یک و دو مولکول آب انجام شده است. بدین منظور ساختار بهینه توتومرهای مختلف مولکول مورد نظر بدست آمده‌اند. همچنین با استفاده از محاسبات فرکانس در سطح محاسباتی مشابه، خواص ترمودینامیکی تعادل‌های مختلف توتومری از قبیل E∆، H∆، G∆ وKeq بدست آمده‌اند. سپس با استفاده از روش‌های QST2 و QST3 حالت های گذار تعادل‌های توتومری مختلف مولکول3-آمینو-1H-4،2،1- تری‌آزول-5)4H (- اٌن و مقادیر سینتیکی و ترمودینامیکی آنها محاسبه شده‌اند. اثرات تونل‌زنی نیز بر روی سرعت واکنش‌های مربوطه بررسی شده‌اند. نتایج نشان میدهند ثابت سرعت واکنش‌های توتومری مورد بررسی نسبت به اثرات تونل‌زنی حساسیت بالایی دارند و سرعت واکنش های توتومری در حدود چهار تا پنج برابر افزایش می‌یابند. همچنین محاسبات حالت گذارنشان می دهند در غیاب مولکول‌های آب سد انرژی مقدار بالایی دارد و سرعت واکنش های توتومری عمدتاً بدون حضور کاتالیزور خیلی آهسته بوده به عبارتی انجام‌پذیر نیستند. Manuscript profile
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  2 - Investigation of C-O tautomerism in a derivative of Flucytosine: A DFT study
  بهزاد چهکندی
  In this research investigation of tautomerism and transition states of 6-Hydroxy 5-Flourocytosine from 1,3 proton transfer between oxygen and carbon atoms in the gas phase and in solution and in a micro hydrated environment with 1-3 water molecules was performed by quan More

  In this research investigation of tautomerism and transition states of 6-Hydroxy 5-Flourocytosine from 1,3 proton transfer between oxygen and carbon atoms in the gas phase and in solution and in a micro hydrated environment with 1-3 water molecules was performed by quantum calculations at the DFT/B3LYP/6-31++G(d,p) level of theory. For this purpose, the optimized geometries of various tautomers of the desired molecule were obtained. Also by using frequency calculations at the same level thermodynamic properties of different tautomeric equilibriums such as ΔE, ΔH, ΔG and Keq were obtained. Then transition states of various tautomeric interconversion of 6-Hydroxy 5-Flourocytosine and it’s kinetic and thermodynamic amounts were calculated by QST2 and QST3 methods. And also the tunneling effects on rates of reaction were investigated. The results show in both gas phase and solution, rate constants of tautomeric reactions have high sensitivity on tunneling effects and rate of tautomeric interconversion increase by about five or more. Also transition state calculations show in absence of water assisted molecules the tautomeric interconversion reacctions have high barrier energy and so are very slow, in other word they can not be done Manuscript profile
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  3 - A tautomerism in 2-amino-7H-purine-6-thiol: Theoretical study using implicit/explicit salvation models
  Aeyed Javad Hosseini بیتا محمداصغری
  A theoretical study at the B3LYP/6-31++G(d,p) level was performed on the tatumerization of 2-amino-7H-purine-6-thiol into 2-amino-9H-purine-6-thiol. Such a tautomerism can take place via three different pathways namely A, B, and C. The energetic results associated with More

  A theoretical study at the B3LYP/6-31++G(d,p) level was performed on the tatumerization of 2-amino-7H-purine-6-thiol into 2-amino-9H-purine-6-thiol. Such a tautomerism can take place via three different pathways namely A, B, and C. The energetic results associated with the gas phase reveal that pathways A, B, and C display a very high activation Gibbs free energy of 47.6, 69.4, and 52.1 kcal/mol, respectively, indicating this process cannot take place in the gas phase. When solvent effects of water are taken into account through a continuum of a uniform dielectric constant, the gas phase activation Gibbs free energies increase to 51.1, 71.9, and 55.4 kcal/mol along pathway A, B, and C, respectively, emphasizing long range solute-solvent interactions do not play a key role in the considered tautomerization. The studied process can easily take place by inclusion of three molecules of water in which a significantly reduced activation Gibbs free energy of 24.8 kcal/mol indicates the predominance of short range solute-solvent interactions over the long range ones. Combination of short range and long range solute-solvent interactions lead to an activation Gibbs free energy of 23.6 kcal/mol for tatumerization of 2-amino-7H-purine-6-thiol into 2-amino-9H-purine-6-thiol. This value clearly points out that employing a polar and protic solvent is able to noticeably reduce the barrier of tatomerization. Manuscript profile
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  4 - Study and comparison of Equilibrium vs. resonance in keto-enol tautomerization in some piroxicam derivatives
  abolghasem shameli Ebrahim balali sara hallajian behrooz yousefzadeh
  The Piroxicam derivatives are nonsteroidal anti-inflammatory drug (NSAID) used to treat pain and help relieve symptoms of arthritis. Which has two or more forms are tautomers, That both form tautomers due to the flexible structure and the possibility of turning around b More

  The Piroxicam derivatives are nonsteroidal anti-inflammatory drug (NSAID) used to treat pain and help relieve symptoms of arthritis. Which has two or more forms are tautomers, That both form tautomers due to the flexible structure and the possibility of turning around bonding C-C, C-O, C-N and C-S. The hydrogen-bond also play a very important roles in structure compound because Intramolecular and intermolecular hydrogen bond in which the different. In this study, theoretical and computational accuracy using BPV860 / 6-311G ** in the gas phase with software Gaussian 03. Infrared Spectroscopic and Theoretical Studies on the derivetives piroxicam. Relationship between the structure and the stability of these enols was discussed. That enol- keto or imine- enamine forms easily converted into stable forms Manuscript profile