Objective: The aim of this study was to study some properties of the pharmaceutical compound (6-mercaptopurine) a number
of theoretical methods were carried out to calculate their molecular energy, the length of the bonds and angles, in addition
to their chemical forms and the binding sites with the enzyme as important anti-cancer inhibitors.
Methods: The intramolecular hydrogen bond, molecular structure, and vibrational frequencies of 6- Mercaptopurine have
been investigated by means of density functional (DFT and AM1) methods with 6-311++G basis.
Results: The nature of these interactions, known as resonance assisted hydrogen bonds, has been discussed. As a geometrical
indicator of a local aromaticity, the geometry-based HOMA index has been applied. Additionally, the linear correlation
coefficients between substituent constants and selected parameters in R position have been calculated.
Conclusion: The results show that the hydrogen bond strength is mainly governed by the resonance variations inside the
chelate ring induced by the substituent groups. The topological properties of the electron density distributions for 6- MP
H…N intra molecular bridges have been analyzed .Finally, the natural population analysis methods has been used to evaluate
the hydrogen bonding interactions.