A Comparative Reactivity Study of Adenine versus Guanine Base through Transition State Formation with cis-Platinum(IV) Complex using DFT

L.H. Khdium and A.A. Ali Drea*

Department of Chemistry, College of Science, University of Babylon, Hilla 51002, Iraq

*Corresponding author: E-mail: aadreab22@yahoo.com; liqaa.aljailawi@uokufa.edu.iq


B3LYP, Lanl2DZ basis sets at density functional theory (DFT) method has been used on a ground state geometry optimized for all proposed structures that have been involved in this study. Structural parameters such as bond lengths, bond angles and dihedral angles have been calculated in the same way to achieve a global reactivity description of Pt(IV) complex. We suggested a minimal energy structure of diaminobis((4-hydroxy-4-butanol)oxy)platinum(IV) chloride complex (DOP) as a new chemotherapy formula of cis-platinum complex. The reactive site of nucleophilic attachment at DOP occurs on carbon atoms due to their positive charge, while other atoms (nitrogen, oxygen, chlorine) are carried negative charges due to the delocalization of electron pair by a resonance effect. Bonds of Pt-Cl with 2.290 Å are more reactive bounds toward the replacement reactions than other chemical bonds in the DOP complex. Investigation revealed that the thermodynamic functions values are increased due to increasing vibrational intensities of cisplatin complex. The fourth transition state (TS4) is the most probable transition state than other suggested transition states for both guanine and adenine bases. The TS4 of platinum complex binding with guanine is the most probable by a factor of -18.134 a.u. of optimization energy value than other suggested states. TS4-guanine is the most probable than other suggested states by factor 7.354 kcal/mol of zero point energy (ZPE). Hence, platinum complex (DOP) is binded with guanine base of DNA through N7.


DFT studies, Adenine, Guanine base, cis-Platinum(IV) complex.

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