-

Abstract

Optimized ground state configurations of some radical adducts of α-phenyl-N-tert-buthyl nitrone (PBN) in benzene and water solutions were calculated using DFT(B3LYP) and HF methods with 6-311++G(d,p) and LanL2ZD levels. The radicals C2H5, CF3, C6H5, OOH, CO2, NH2, SO3 and CCl3 whose structures to be calculated, were assumed to be trapped in the host. The calculated isotropic hyperfine coupling constants of the trapped radicals were seen to be in good agreement with the corresponding experimental data. After the calculations it was concluded that HF method is superior rather than DFT/B3LYP method for hyperfine calculations of the radicals given above. The geometrical parameters for the ground state optimized structures of all the assumed radical adducts and the bonding energies of all the radicals are given

Keywords

• Hyperfine coupling constant, spin trapping, radical, PBN, EPR, DFT, HF

Benzen ve Su Çözeltilerinde α-Fenil-N-Tert-Bütil Nitrone'nin Bazı Radikal Ürünlerinin Teorik Optimize Yapıları ve İnce Yapı Çiftlenim Sabitleri

Abstract

Özet: Benzen ve su çözeltilerinde α-fenil-N- tert-bütilnitrone (PBN)'nin bazı radikal ürünlerinin temel hal optimize yapıları 6-311++G(d,p) ve LanL2DZ seviyelerinde DFT (B3LYP) ve HF metotları kullanılarak hesaplandı. Tuzaklanmış radikaller olarak, C2H5, CF3, C6H5, OOH, CO2, NH2, SO3 ve CCl3 kullanıldı. Tuzaklanan radikallerin hesaplanan izotropik ince yapıçiftlenim sabitleri, karşılık gelen deneysel verilerle uyum içinde olduğu görüldü. Elde edilen bütün teorik sonuçlardan bu radikaller için ince yapıçiftlenim sabitleri hesaplamalarında, HF metodunun DFT/B3LYP metoduna göre deneylerle daha iyi uyumlu sonuçlar verdiği sonucuna ulaşıldı. Ayrıca bütün radikal ürünlerinin temel hal optimize yapılarına ait geometrik parametreler tablo halinde verildi ve tuzaklanmış bütün radikallerin bağlanma enerjileri hesaplandı. Anahtar kelimeler: İnceyapı çiftlenim sabiti, spin tuzaklama, radikal, PBN, EPR, DFT, HF Calculated Optimized Structures and Hyperfine Coupling Constants of Some Radical Adducts of -Phenyl-N-Tert-Buthyl Nitrone in Benzene and Water Solutions Abstract: Optimized ground state configurations of some radical adducts of α-phenyl-N-tert-buthyl nitrone (PBN) in benzene and water solutions were calculated using DFT(B3LYP) and HF methods with 6-311++G(d,p) and LanL2ZD levels. The radicals C2H5, CF3, C6H5, OOH, CO2, NH2, SO3 and CCl3 whose structures to be calculated, were assumed to be trapped in the host. The calculated isotropic hyperfine coupling constants of the trapped radicals were seen to be in good agreement with the corresponding experimental data. After the calculations it was concluded that HF method is superior rather than DFT/B3LYP method for hyperfine calculations of the radicals given above. The geometrical parameters for the ground state optimized structures of all the assumed radical adducts and the bonding energies of all the radicals are given. Key words: Hyperfine coupling constant, spin trapping, radical, PBN, EPR, DFT, HF

Keywords

• İnceyapı çiftlenim sabiti, spin tuzaklama, radikal, PBN, EPR, DFT, HF

References

1. Buettner G.R.,1987. Spin trapping: ESR parameters of spin adducts, Free Radical Biology & Medicine, 3: 259-303.
2. Feller D., DavidsonE.R., 1984.Ab initio configuration-interaction calculations of the hyperfine-structure in small radicals, Journal of Chemical Physics, 80: 1006-1017.
3. Haire D.L., Oehler U.M., Krygsman, P.H., Janzen, E.G., 1988. Correlation of radical structure with EPR spin adduct parameters: utility of the proton, carbon-13, and nitrogen-14 hyperfine splitting constants of aminoxyl adducts of PBN-nitronyl-13C for three-parameter scatter plots, Journal of Organic Chemistry, 53: 4535–4542.
4. Chen Bo-Z., Huang Ming-B., 1999. Hyperfine structure in HCS and related radicals: a theoretical study, Chemical Physics Letters, 308: 256-262.
5. Engström M., Vahtras O., Agren H., 1999. Hartree-Fock linear response calculations of g-tensors of substituted benzene radicals, Chemical Physics, 243: 263-271.
6. Engström M., Vahtras O., Agren H., 2000. MCSCF and DFT calculations of EPR parameters of sulfur centered radicals, Chemical Physics Letters, 328: 483-491.
7. Ucun F., Aydın S.G., 2014. Calculated optimized structures and hyperfine coupling constants of some radical adducts of a-phenyl-N-tert-buthyl nitrone in water and benzene solutions, Journal of Organometallic Chemistry, 759; 27-32.
8. Frisch M. J., et al.,2003. Gaussian 03, Revision C.02, Gaussian Inc., Pittsburgh, PA.

9. Frish A., Nielsen A. B., Holder A.J., 2001. Gauss View User Manual, Gaussian Inc. Pittsburg, PA.
10. Boys S. F., Bernardi F., 1970. The calculation of small molecular interactions by the differences of separate total energies. Some procedures with reduced errors, Molecular Physics, 19: 553-566.
11. Fatih UCUN e-posta: [e-mail]