The development of new effective chemical substances, such as new drugs, herbicides or insecticides, is essential for the survival of an agro-chemical and pharmaceutical industry. The process of finding biologically active compounds is very research-intensive and time consuming, illustrated by the fact that typically only about 1 of 10’000 synthesized chemical substances can finally be used as a commercial product The starting point for the development of a new substance is typically a putative “lead substance”, i.e. a substance believed to be chemically modifiable into a biologically very active compound. Once this lead substance is found, numerous modified substances are synthesized and their biological activity is measured. By relating the structural properties of these substances to their biological activity, the physico-chemical properties necessary for high biological activity are identified. This information is then used to synthesize new substances with hopefully higher biological activity. Then a new cycle in the process of developing new active substances is started.