The semiempirical and DFT methods in studies on geometry and energetics of AMSA isomers: comparison of m-AMSA and o-AMSA properties

摘要

Calculations on the structure of m-AMSA using the semiempirical MNDO, AM1 and PM3 and density functional-B3LYP/6-31G(d) methods are reported. To assess the accuracy of these methods in predicting the structure of m-AMSA-base and m-AMSA-cation, the resulting geometrical parameters are compared with available crystallographic data. Structural and electronic properties of m-AMSA and its inactive isomer—o-AMSA calculated using the above mentioned methods are also described and differences between these two compounds are tried to be found. A marked difference in the biological activity observed between the two molecules can be attributed to geometric factors and also differences in their electronic properties.