Thermodynamic Parameters of Cis-Platin and Trans-Platin Complexes with Guanine in Water, A DFT Study

The binding energy and Thermodynamic Parameters of cis- Platinum Di Ammino Chlorine (cis-[Pt(NH3)2Cl]+) and trans- Platinum Di Ammino Chlorine (trans- [Pt(NH3)2Cl]+) complexes withGuanine has been studied by density functional theory (DFT) calculations in water. The bindingenergies (Ebin) of cis- and trans-[Pt(NH3)2ClG]+ are calculated to be 79.38 kcal/mol and 74.98kcal/mol, respectively. The binding energy (Ebin) of cis-[Pt(NH3)2ClG]+ turns out to be energeticallymore favorable by about 1.88 kcal/mol than the trans-[Pt(NH3)2Cl]+. At the point of thermodynamic,the formation of cis-[Pt(NH3)2ClG]+(aq)with
G (Solv) equal to -10.36 kcal/mol is more favorablethan trans-[Pt(NH3)2ClG]+(aq) with 16.21 kcal/mol.