Molecular Modeling Studies of Some Uracil and New Deoxyuridine Derivatives

Table 4

(a) Solvation energy, frontier orbital energies, dipole moment, and zero-point energy of the six possible tautomers of 5-FU (see Figure 8). (b) Total energies in the gas phase () and aqueous solution () in Hartree (atomic unit) and thermodynamic parameters of the six possible tautomers of 5-FU.

(a)

Tautomer	Solvation (kJ/mol)	HOMO; (eV)	LUMO (eV)	Dipole; (debye)	ZPE; (kJ/mol)
T6	−38.92	−6.79	−1.38	3.90	207.48
T1	−80.48	−6.16	−1.26	5.03	200.36
T5	−105.10	−5.80	−1.02	3.41	192.36
T2	−105.35	−6.05	−2.04	6.84	198.77
T4	−110.20	−6.29	−1.82	5.30	199.15
T3	−142.32	−6.34	−0.96	8.92	199.35

(b)

Tautomer	(au)	(au)	(au)	(J/mol)	(au)
T6	−514.035880	−514.050703	−513.949227	342.8	−513.988156
T1	−513.948808	−514.003016	−513.882627	352.01	−513.922601
T5	−513.956560	−513.998531	−513.825376	361.45	−513.866422
T2	−513.967035	−513.997688	−513.867448	352.56	−513.907485
T4	−513.951220	−513.991344	−513.872636	352.57	−513.912674
T3	−513.907176	−513.947206	−513.864678	353.32	−513.90480