2. Materials and Methods
The starting structures of all the modifications were generated by considering the crystal structures of respective standard modifications. Other modifications were built using molecular building and visualization software Gaussview43. The 2D structures of all the modifications are given in Figure 1 and the modification details are given in Table 1. The proposed novel modifications have been labelled as A1 to A5 in Figure 1. The complete methodology can be divided into three sections, conformational search and identifying most stable conformation, running quantum mechanical calculations in various levels and quantum chemical descriptor derivation.