Theoretical study of substituent effects on electronic and structural properties of 2,4-diamino-5-para-substituted-phenyl-6-ethyl-pyrimidines

Density functional theory (DFT) method at the level of B3LYP with 6-311G(d) basis set was used to investigate the effects of a variety of substituents (H, NH2, NMe2, OCH3, CH3, Cl, Br, CN, NO2) on the electronic and structural properties of 2,4-diamino-5-p-substituted-phenyl-6-ethyl-pyrimidines. The investigation showed that the atomization energy was affected by substitution. Likewise, the molecular orbitals HOMO and LUMO and energy gap DE were affected by the substituent. Dipole moment was also affected by the introduction of the substituent. On the other hand, the Mulliken charges at only C1′, C2 and N7, were correlated with both MSP and DSP models