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The presence of organophosphorus compounds (OPs) in the environmental counterparts has become an important problem because of their toxicity. In this study, the photocatalytic degradation reactions of the three OPs with hydroxyl radical were investigated by both experimental and quantum chemical methods. Photocatalytic degradation kinetics of the examined organophosphorus compounds were investigated under UV-A irradiation using TiO2 as the photocatalyst. The effects of the initial concentrations on the degradation rate have been examined. There was an observable loss of OPs in the presence of TiO2 photocatalyst under UV-A at 0.2 g TiO2 per 100 mL. The quantum chemical calculations have been carried out by the density functional theory (DFT) at B3LYP/6-31g(d) level. The reaction pathways were modelled to find the most probable mechanism for OPs with the OH radical and to determine the primary intermediates. The rate constants of the eight reaction paths were calculated by the transition state theory. Conductor-like polarizable continuum model (CPCM) was used as the solvation model with the intention of understanding the water effect. The theoretical results were in agreement with experimental ones. © 2021 Serbian Chemical Society. All rights reserved.18,164Acknowledgement. The authors of this research has greatfully acknowledgemented to financially support of Tekirdag Namık Kemal University Research Project with the project number of NKUBAP.01.GA.18.164

Rn-18, Hiv-1 Vif-Apobec3g İnhibitörünün Karakterizasyonu Ve Dft Yöntemiyle Moleküler Modellenmesi

RN-18, HIV-1 Vif-APOBEC3G eksen inhibitör çalışmalarında yapı-aktivite ilişkisini ve optimizasyonunu tarif etmekte kullanılır. RN-18 halkasının C, B halkası, A halkasının, köprü A-B ve köprü B-C hedefli modifikasyonlarının benzeri (4g ve 4i) ve geliştirilmiş 5, 8b ve 11 ile yeni inhibitörleri oluşturan çok önemli yapısal özelliklerini belirlemek için faaliyetleri gerçekleştirilmiştir. RN-18 analogları, iki etkili suda çözünür, aynı zamanda 17 ve 19’ların sonucunda ortaya çıkmıştir ve bu bileşik 19 ile farmakolojik çalışmaların sonuçlarını açıklamıştır. Bu çalışmada ise bulgular sonucunda hedef RN-18 protein ve analoglarının tanımlanması için daha etkili inhibitörler geliştirilmiştir. Sentez sırasında etkili olan yeni inhibitorleri geliştirmek için yapısal temel anlama üzerinde durulmuştur. Böylece A3G katalitik alanı yapısı önermek için RN-18 proteinden yola çıkılıp bir homoloji modelleme yaklaşımı yapılarak, HIV-1 viral enfeksiyon faktörlerine karşı küçük molekül inhibitörlerinin keşifleri geliştirilmiştir. Kuantum mekaniksel hesaplar gaz fazında yoğunluk fonksiyoneli teorisi DFT/B3LYP/631G* yöntemiyle yapılmıştır ve her molekülün optimum geometrik parametreleri termodinamik ve elektronik özellikleri hesaplanmıştır. Kemoterapilerde özellikle, HIV-1 ters transkriptaz proteaz ve HIV-1 proteini hedef inhibisyonunda, kazanılmış bağışıklık eksikliği sendromu (AIDS) hastaların hayatlarını uzatmak için yardımcı olmuştur. HIV-1 replikasyonunun yüksek oranda ortaya çıkması, Anti-HIV’in kemoterapi alanında ilaca direnç gösteren türleri ortaya çıkartmıştır. HIV-1 (MDR) ilacı HIV-1 MDR mutantlarına önemli ölçüde karşı direnç sağlamıştır. Sonuç olarak, sonuçlar VIF-APOBEC3G etkileşimi hedefleyen molekülleri optimize etmek ve yeni anti HIV ilaçların gelişiminde yol göstermek için kullanılabilir. Bu çalışma bilim açısından önemli bir yer edinecektir

Possible reaction pathways of the acetamiprid molecule according to the DFT calculation method

Acetamiprid, the major active ingredient of some pesticides, is a subclass of the neonicotinoid group and is used especially against whitefly, aphididae, leaf bugs, potato bugs which affect products such as cotton, tobacco, potato, tomato, nut, citrus, planted in greenhouses and fields. Quantum chemical calculations of density functional theory (DFT) were used to investigate the structural and physical characteristics of acetamiprid. The analysis was made on the probable reaction path of acetamiprid molecule with OH radicals. The calculation of the optimized geometry and the geometric optimization for determination of the lowest energy status were made by the Gauss View 5 and the Gaussian 09 program. Activation energy for the probable reaction paths was calculated and its most stable states from the thermodynamic perspective were determined for the different phases. The aim of this study is to estimate the degradation mechanism of acetamiprid molecule in gaseous phase, in ethanol and water as polar solvents, and in chloroform as a partially polar solvent, all of which were analysed through the conductor-like screening solvation model (COSMO) as the solvation model. The probable reaction path of the activation energy was calculated, and its most stable state in the thermodynamic frame was determined for these phases. © 2018 Bulgarian Academy of Sciences, Union of Chemists in Bulgaria.Acknowledgements: The authors greatly appreciate Namik Kemal University Research Foundation for financial support. Project number: NKUBAP.01.GA.18.164 The authors declare that there is no conflict of interests regarding the publication of this paper

Analysis of the reaction kinetics of aminotoluene molecule through DFT method

In this study, the most probable reaction paths of aminotoluene (o-toluidine) molecule with OH radical were analyzed. The optimized geometry was calculated via Gauss View 5. Subsequently, the lowest energy status was found out through geometric optimization via Gaussian 09 programme. The geometric structure analysis and bond lengths were also calculated. This study aims to determine the most probable path for the product distribution of aminotoluene and OH radical interaction in gas phase and aqueous media. Quantum mechanical methods were used to indicate the impact of reaction rate over primary intermediate, hydroxylated intermediate, and finally the impact of water solvent. With the aim to determine the intermediates occurring at the reaction of aminotoluene degradation, geometric optimization of the reactant and transition status complexes were realized through Density Functional Theory (DFT) method. Based on the Quantum mechanical calculation, all probable rate constants of reaction paths were calculated by using Transition Status Theory (TST). For the determination of the transition status of the reaction, C-O bonds were taken as reference. Activation energy for probable reaction paths of all transition status complexes, and their most stable state were calculated from the thermodynamic perspective for the gas phase and aqueous media. The impact of water solvent was investigated by using COSMO as the solvation model.Namik Kemal University Research FoundationNamik Kemal University [NKUBAP.00.10.AR.12.05]The authors greatly appreciate Namik Kemal University Research Foundation for financial support. Project number: NKUBAP.00.10.AR.12.0

Determination of Total Antioxidant Capacity of Rosehip (R. arvensis Huds) Growing in Turkey and Rosehip Species by Using CUPRAC Spectrophotometric Method

L-Ascorbic acid (vitamin C) is the most important vitamin for human nutrition supplied by fruits and vegetables, and is the main water-soluble antioxidant in human plasma. L-Ascorbic acid is reversibly oxidized to form dehydroascorbic acid, which also exhibits biological activity. As a potent antioxidant, L-ascorbic acid scavenges reactive oxygen species including superoxide, protects isolated low density lipoprotein against oxidative modification and plays an important role in the regulation of intracellular redox status. The aim of this study was to measure antioxidant capacity of R. arvensis Huds and rosehip species, by using CUPRAC (the cupric ion reducing antioxidant capacity) spectrophotometric method

Possible reaction pathways of selected organophosphorus and carbamate pesticides according to the DFT calculation method

This research was carried out in order to analyse the reactions of three organophosphorus (OP) and three carbamate (CB) pesticides with the hydroxyl radical (.OH), and their degradation paths. The studied organophosphorus pesticides are Azamethiphos, Coumaphos, Temephos, and the carbamate pesticides are Methiocarb, Carbofuran, Pirimicarb. Initially, in the reactions, the initial geometries of the reactants were determined. Geometric optimisations were performed using the DFT/B3LYP/6-31G (d) basic set of Quantum Mechanical Density Functional Theory (DFT). For each molecule, degradation reaction mechanisms were tried to be clarified using the calculated energy values. Since the reactions of pesticides with .OH are essential in terms of both water treatment and atmospheric chemistry, energy values were calculated both at gaseous phase and aqueous phase by modelling the solvent effect. For each molecule, fragments were found out by analysing the bond lengths, bond angles, and energy values, and as a result, degradation paths were determined. © 2022 Bulgarian Academy of Sciences, Union of Chemists in Bulgaria.NKUBAP.01Acknowledgements: The authors greatly appreciate Namık Kemal University Research Foundation for financial support. Project number: NKUBAP.01.GA.20.260 The authors declare that there is no conflict of interests regarding the publication of this paper

The most stable transition state complexes of the aminotoluene molecule

In this study the most probable reaction paths of ATnm, OATnm, MATnm, PATnm, NMATo and NMATm transition states with OH radicals have been analyzed. The optimized geometry was calculated via Gauss View 5. Subsequently, the lowest energy level was found by geometric optimization via the Gaussian 09 programme. The geometrical structure analysis and bond lengths were also calculated. This study aims to determine the most probable path for the product distribution of transition state complexes and OH radical interaction in the gas phase and aqueous media. Quantum mechanical methods were used to indicate the impact of the reaction rate over the primary intermediate, hydroxylated intermediate and finally the impact of water solvent. With the aim to determine the intermediates occurring at the reaction of transition state complexes degradation, the geometric optimization of the reactant and transition state complexes were realized through semiempirical AM1 and PM3, ab initio Hartree-Fock HF/3-21G, HF/6-31G* and Density Functional Theory (DFT) methods. Determining the most appropriate method and the reliability of the method are compared and evaluated theoretically. Based on the Quantum mechanical calculation, all the probable rate constants of reaction paths were calculated by using Transition State Theory (TST). In order to determine the transition state of the reaction, C-O bonds were taken as a reference. Activation energy for probable reaction paths of all transition state complexes, and their most stable state were calculated from the thermodynamic perspective for the gas phase and aqueous media. The impact of water solvent was investigated by using COSMO as the solvation model.Namik Kemal University Research FoundationNamik Kemal University [NKUBAP.00.10.AR.12.05]The authors greatly appreciate the financial support of the Namik Kemal University Research Foundation. Project number: NKUBAP.00.10.AR.12.05

Effect of molecular properties on the photocatalytic degredation rates of pyridazine

In this study, with the intention of determining the primary intermediates, the photocatalytic degradation reaction of pyridazine which has been accepted as the pollutant was modelled. Geometry optimizations of the reactants, the product radicals, the pre-reactive and the transition state complexes were performed for all the possible reaction paths. The Hartree-Fock calculations were carried out on HF/6-31G? basis set. Based on the results of the quantum mechanical calculations, the rate constants for all the possible reaction paths were calculated by means of the Transition State Theory. The difference in the rates of reaction paths were explained in terms of the presence of hydrogen bonds in the transition state complexes

Theoretical and experimental photodegradation of Phosmet via oxidation techniques in the presence of aqueous TiO2suspension

This study is conducted with the aim to analyze the reaction kinetics of Phosmet with the OH radical, and to determine its mechanism. Due to the lack of experimental evidence of radical intermediate products occurring during the reactions, the theoretical stage has been quite informative. In this study, in order to theoretically determine all probable reaction paths, geometric optimization of the reactants and transition state complexes was conducted using DFT/B3LYP/6-31G(d) basic set of Quantum Mechanical Density Functional Theory (DFT). As a result of the calculations, the energy values at ground state, and rate constant and activation energies (Ea) at transition state (TS) of the probable reaction paths were determined. And finally, the primary intermediate products were found out by the determination of the atom where the OH radicals attach, and the hydrogen atoms they had removed. The reaction mechanism was clarified through the determination of the intermediate products. Since the reactions of pesticides with OH radical are important both in terms of water purification and atmospheric chemistry, the calculations were carried out in gaseous phase and also at aqueous phase by modelling the solvent impact. In the experimental stage, the degradation reactions under UV-light impact of the pesticide, chosen as pollutant, in aqueous TiO2 suspensions, were analyzed. At the end of this research, the optimum photocatalyst amount and TiO2 concentration were determined. The degradation rates were determined, the impact of the initial concentration was analyzed, and the reaction products were identified. © 2021 Bulgarian Academy of Sciences, Union of Chemists in Bulgaria

Forced Degradation Studies of Nateglinide by the First-Order Derivative Spectrophotometric Method and the Density Functional Theory of the Nateglinide Molecule

Nateglinide (NAT) is an oral antihyperglycemic agent used for the treatment of noninsulin-dependent diabetes mellitus. We evaluated the NAT stability under various forced degradation tests (acidic, basic) and predicted the degradation mechanism of the NAT molecule in the gaseous phase and aqueous media. A first-order derivative spectrophotometric method was used for the identification of NAT and the products of its degradation. NAT appeared to be stable in acidic but not in basic media. A probable reaction path of the NAT molecule with OH radicals was analyzed. The optimized geometry was calculated with Gauss View 5. Subsequently, the lowest energy status was determined through geometric optimization using Gaussian 09 software. Aiming to determine the intermediates in the photocatalytic degradation mechanism, the geometric optimization of the molecule was realized using the density functional theory method. The activation energy for the probable reaction path was calculated, and their most stable state from the thermodynamic perspective was determined for the gaseous phase and aqueous media. The predicted mechanism was confirmed by comparison with the experimental results on simple structures reported in the literature.Research Fund of the University of Namik Kemal [NKUBAP.00]This work was supported by the Research Fund of the University of Namik Kemal (Project No. NKUBAP.00.GA.19.217)