Principles of the molecular morphing approach. Molecular morphing generates a path in chemical space consisting of structures (referred to as morphs) lying between a start molecule M
and a target molecule M
. In each iteration i + 1 a set of morphs is generated by randomly applying morphing operators (see Figure 2) at molecules from the iteration i. The morphs from the iteration i are accepted as candidates for the iteration i + 1 with the probability derived from their distance to the target molecule. A more detailed description of the algorithm is given in Additional file 1.