Molecular structure design, geometrical concept

For the conception of new molecular structures it is first necessary to be able to evaluate the geometrical properties of reference molecules. Theoretical calculations of conformations are now accurate enough so that this point can be taken as read even for molecules not yet studied experimentally. With the aid of these now classical techniques the drug-designer can go further and address himself to the three following fundamental items ... 

One learns from these molecular complexes that equivalent synthons can lead to virtually identical crystal structures. Synthons in, V and VI are chemically and geometrically equivalent though they originate from different molecules, a nitrile, an N-oxide and a nitro compound. These three synthons are used in crystal design in almost the same way. So, different molecules may yield similar crystal structures if they are capable of forming equivalent synthons. This is a powerful concept because it establishes a many-to-one correspondence between molecular and crystal structures. 

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