Hybrid quantum chemical studies for the methanol formation reaction assisted by the proton transfer mechanism in supercritical water: CH3Cl+nH2O→CH3OH+HCl+(n−1)H2O

Hori, Takumi; Takahashi, Hideaki; Nitta, Tomoshige

doi:10.1063/1.1611175

Cited by 22 publications

(6 citation statements)

References 52 publications

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“…A QM/MM simulation has been performed for chloromethane hydrolysis is supercritical water . The temperature (600 K) and density (0.33 g cm −3 ) used in this study are completely from those in this work, and KIEs were not reported.…”

Section: Resultsmentioning

confidence: 99%

QM/MM kinetic isotope effects for chloromethane hydrolysis in water

Ruiz‐Pernía

Ruggiero

Williams

2013

J of Physical Organic Chem

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Computational simulations for chloromethane hydrolysis have been performed using hybrid quantum-mechanical/ molecular-mechanical methods with explicit solvation by large numbers of water molecules. In the first part of the paper, we present results for 2 2 H 3 , 1 14 C, and 1 37 Cl kinetic isotope effects (KIEs) at 298 K with both the AM1/TIP3P and B3LYP/6-31G* QM methods for the nucleophile H 2 O and electrophile CH 3 Cl surrounded by 496 solvating TIP3P water molecules. An initial Hessian computed for a subset of this system including up to 104 MM water molecules was reduced in size by successive deletion of rows and columns, and KIEs were evaluated for each. We suggest that accurate calculations of KIEs in solvated systems should involve a subset Hessian including the substrate together with any solvent atoms making specific interactions with any isotopically substituted atom. In the second part of the paper, the ensemble-averaged 2 a-2 H 3 KIE calculated with the B3LYP/6-31+G(d,p)/TIP3P method is shown to be in good agreement with experiment. This comparison is meaningful because it includes consideration of uncertainties owing to sampling of a range of representative thermally accessible solvent configurations. We also present ensemble-averaged 14 C and 37 Cl KIEs which have not as yet been determined experimentally.

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Section: Resultsmentioning

confidence: 99%

QM/MM kinetic isotope effects for chloromethane hydrolysis in water

Ruiz‐Pernía

Ruggiero

Williams

2013

J of Physical Organic Chem

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“…Elde edilen bu veriler MOPAC2012 programına aktarılarak hesaplama işlemi tamamlanmıştır. MOPAC2012 paket programı içerisinde yer alan PM7 hesaplama yöntemi ile hesaplamalar sulu (ɛ=78,4) [21] fazda ve kan (ɛ=58) [22] fazında T=298K ve T=310K'de yapılmıştır [23]. Hesaplama sonuçlarından üçlü ilaç moleküllerin entalpi (H), oluşum ısıları (Hf) ve entropi (S) değerleri okunmuştur.…”

Section: 1hesaplamada Kullanılan İlaç Molekülleriunclassified

Di̇yabet, Kolesterol Ve Tansi̇yon Sinifina Ai̇t Bazi İlaçlarin Üçlü İlaç Etki̇leşi̇mleri̇ni̇n Semi̇-Empi̇ri̇k Yöntemler İle Teori̇k Olarak İncelenmesi̇

Harzadın

2016

BTDB

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ÖZETDiyabet (D), kolesterol (K) ve tansiyon (T) sınıfına ait seçilmiş ilaçların üçlü etkileşimleri semi-empirik yöntemler ile teorik olarak incelendi. İlaç moleküllerinin en kararlı geometrileri CS Chem3D programı ile MM2 yönteminde belirlendi. Kararlı geometrilerden input dosyaları elde edildi. PM7 hesaplama yöntemi kullanılarak MOPAC2012 paket programında termodinamik hesaplamaları su (ɛ=78) ve kan (ɛ=58) fazında iki farklı sıcaklıkta (T=298K ve T=310K) yapıldı. Hesaplama sonuçlarından üçlü ilaç moleküllerinin entalpi (H), oluşum ısıları (Hf) ve entropi (S) değerleri okundu. Bu değerlerden yararlanılarak tekli ve üçlü moleküllerin Gibss Serbert Enerjisi (ΔG ve ΔGf) değerleri hesaplandı.MOPAC2012 programına göre vücut sıcaklığında (T=310K) kan fazında belirlenen K3-D3-T2 ve K1-D2-T3 üçlü etkileşim yapan moleküller kullanıldığında birbirlerinin etkisini azaltacağı ya da artıracağı için mutlaka hekim tarafından doz ayarlaması yapılarak kullanılması gerektiği bulunmuştur.Anahtar Kelimeler: Diyabet, İlaç etkileşimi, Kontrollü ilaç salımı, Kolesterol, Mopac2012, Tansiyon SEMI-EMPIRICAL DETERMINATION OF DIABETES, CHOLESTEROL AND BLOOD PRESSURE DRUG ACTIVE COMPOUNDS AND THEIR TERNARY INTERACTIONS ABSTRACTThe ternary interactions of the selected medications belonging to diabetes, cholesterol and blood pressure class have been studied theoretically by semi-empirical methods. The most stable geometries of drug molecules have been determined in MM2 method with CS Chem 3D program. The input files have been obtained from stable geometries. In the MOPAC2012 package program, thermodynamic calculations have been held at aqueous (ɛ=78) and blood (ɛ=58) phase in T=298K and T=310K by using the calculation method. The enthalpy (H), formation heats (Hf) and entropy values (S) of ternary drug molecules have been read from the calculation results. By benefiting from these values, the values of Gibbs Free Energy (ΔG and ΔGf ) product and interaction stabilities have been determined.According to the MOPAC2012 program, when K3-D3-T2 and K1-D2-T3 molecules that result in triple interference are determined in body heat (T=310K) blood phase they will increase or decrease effects of each other's when they are used together and should definitely be used by a doctor's dose adjustment.

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“…The electronic structures of the QM subsystem have been determined by utilizing our original code based on the KS‐DFT 38–44. One of the notable features of our code is that the one‐electron wave functions in the QM subsystem are represented by the real‐space grids 45–47.…”

Section: Computational Detailsmentioning

confidence: 99%

The QM/MM‐ER studies for the origin of the antioxidative properties of MCI‐186 in aqueous solutions

Takahashi

Iwata

Kishi

et al. 2011

Int J of Quantum Chemistry

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ABSTRACT:The anionic derivative of the pharmaceutical compound 3-methyl-1-phenyl-2-pyrazolin-5-one (MCI-186) is known to deactivate the free radicals in biological systems by donating its excess electron. For the purpose to investigate the mechanism that the MCI-186 anion exhibits the antioxidative activity in aqueous solutions, we have performed a series of quantum mechanical/molecular mechanical (QM/MM) simulations based on the density functional theory in combination with the theory of energy representation (QM/MM-ER). For the computational convenience, MCI-186 has been modeled by 1,3-dimethyl-2-pyrazolin-5-one (DMP) by substituting the phenyl group in MCI-186 by a methyl one. We have applied the QM/MM-ER approach to compute free energy change dG aq associated with the electron detachment from DMP anion in water. To make comparisons, we have also performed the simulations for a natural radical scavenger, ascorbic acid modeled by 3,4-dihydroxyfuran-2-one (DHF). In the QM/MM-ER approach, the distribution functions of the solute-solvent interaction energy, which serve as fundamental variables to describe the free energy, are to be constructed with the QM/MM force field. The free energy changes dG aq were computed as 99.1, 108.3 kcal/mol for DMP and DHF anions, respectively, whereas that for hydroxyl anion OH À taken as a reference system was evaluated as 138.9 kcal/mol. Thus, it was revealed that the free energies dG aq for DMP and DHF anions are much smaller than that for hydroxyl anion, which directly indicates the high activities of the molecules as electron donors. We found that the small dG aq values can be mainly attributed to the small values in the absolutes of the solvation free energies. The fractional charge analyses provided the evidence that the delocalization of the excess charge on the solute gives rise to the destabilization of

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Hybrid quantum chemical studies for the methanol formation reaction assisted by the proton transfer mechanism in supercritical water: CH3Cl+nH2O→CH3OH+HCl+(n−1)H2O

Abstract: A multilayered-representation quantum mechanical/molecular mechanics study of the SN2 reaction of CH3Br + OH− in aqueous solution A general methodology for quantum modeling of free-energy profile of reactions in solution: An application to the Menshutkin NH 3 +CH 3 Cl reaction in water

Cited by 22 publications

References 52 publications

QM/MM kinetic isotope effects for chloromethane hydrolysis in water

QM/MM kinetic isotope effects for chloromethane hydrolysis in water

Di̇yabet, Kolesterol Ve Tansi̇yon Sinifina Ai̇t Bazi İlaçlarin Üçlü İlaç Etki̇leşi̇mleri̇ni̇n Semi̇-Empi̇ri̇k Yöntemler İle Teori̇k Olarak İncelenmesi̇

The QM/MM‐ER studies for the origin of the antioxidative properties of MCI‐186 in aqueous solutions

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