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Bu çalışmada, antioksidan özellikleri deneysel olarak belirlenmiş bazı 4-benzilidenamino-4,5-dihidro-1H-1,2,4-triazol-5-on türevleri bileşiklerinin Yoğunluk Fonksiyonel Teorisi yöntemiyle antioksidan etkinliklerinin karşılaştırılması yapılmıştır. Yoğunluk fonksiyonel teorisine (DFT) dayanan kuantum kimyasal hesaplamalar, deneysel sonuçlarında en fazla ve en az antioksidan aktiviteye sahip 4-benzilidenamino-4,5-dihidro-1H-1,2,4-triazol-5-on türevlerinin (2a ve 2g için) arasındaki ilişkiyi incelemek için kullanılmıştır. Antioksidan aktivitesi üzerindeki solvasyon etkileri, farklı dielektrik sabitleri (ϵ = 2.25, C6H6 ϵ = 78.39, H2O) ile iletken benzeri polarize süreklilik modeli kullanılarak dikkate alınmıştır. Üç antioksidan reaksiyon mekanizması, hidrojen atom transferi (HAT), tek elektron transfer-proton transferi (SET-PT) ve ardışık proton kaybı elektron transferi (SPLET) açıklanmıştır. Bu mekanizmalardaki adımlarla ilgili reaksiyon entalpileri gaz fazında ve çözücülerde hesaplanmış, hesaplanan sonuçların deneysel değerlerle uyumluluğu tartışılmıştır. Sonuçlar, SPLET'in sulu fazda 2a ve 2g’nin antioksidan aktivitesini tanımlamak için en uygun mekanizma olduğunu göstermiştir, SPLET en termodinamik olarak makul reaksiyon yolunu temsil etmiştir. Hesaplamalar, DFT yöntemiyle nötral moleküller ve anyonlar için rB3LYP/ 6-311++G (2d,2p), radikaller ve katyonlar için uB3LYP/ 6-311++G (2d,2p) temel setleri kullanılarak yapılmıştır.
In this study, the antioxidant properties were experimentally determined and some 4-benzylidenamino-4,5-dihydro-1H-1,2,4-triazol-5-on derivative compounds compared the antioxidant effects with the intensity functional theory method. Quantum chemical calculations based on intensity functional theory (DFT) have been used to study the relationship between the derivatives of 4-benzylidenamino-4,5-dihydro-1H-1,2,4-triazol-5-on (2a and 2g) with the maximum and minimum antioxidant activity in the experimental results. The solvation effects on the antioxidant activity were considered by using a polarized continuity model similar to the conductor with different dielektric fixations (ε = 2.25, C6H6; ε = 78.39, H2O). Three antioxidant reaction mechanisms, hydrogen atom transfer (HAT), single electron transfer-proton transfer (SET-PT) and consecutive proton loss electron transfer (SPLET) have been explained. The reaction entalpils related to the steps in these mechanisms are calculated in the gas phase and solvents, and the calculated results are discussed in compliance with the experimental values. The results showed that SPLET was the most suitable mechanism to determine the antioxidant activity of 2a and 2g in the water phase, SPLET represented the most thermodynamically reasonable path of reaction. The calculations were made using the DFT method using the basic sets of rB3LYP/ 6-311++G (2d,2p) for neutral molecules and anions, uB3LYP/ 6-311++G (2d,2p) for radicals and cations.
In this study, the antioxidant properties of some experimentally determined 4-benzylideneamino-4,5-dihydro-1H-1,2,4-triazol-5-one derivatives of antioxidant properties were compared by density functional theory method. Quantum chemical calculations based on density functional theory (DFT) were employed to study the relationship between 4-benzylideneamino-4,5-dihydro-1H-1,2,4-triazol-5-one derivatives (for 2a and 2g) having the highest and least antioxidant activity in experimental results. The solvation effects on the antioxidant activity were taken into account by using the conductor-like polarisable continuum model with different dielectric constants (ϵ= 2.25, C6H6; ϵ = 78.39, H2O). The three antioxidant action mechanisms, hydrogen atom transfer (HAT), single electron transfer-proton transfer (SET-PT) and sequential protonloss electron transfer (SPLET) were elucidated. The reaction enthalpies related to the steps in these mechanisms were computed in gas phase and solvents, the compatibility of the calculated results with experimental values is discussed. The results showed that SPLET was the most favourable mechanism for describing the antioxidant activity of 2a and 2g in the aqueous phase, SPLET represented the most thermodynamically plausible reaction pathway. Calculations performed by using DFT method at the rB3LYP/6-311++G (2d,2p) level of theory for neutral molecules and anions in the gas and solvation phase, for radicals and cations, uB3LYP/ 6-311++G (2d,2p) basis set has been used.
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