ABSTRACT
This chapter discusses the minor spectrophotometric activities based on the transitions of σ and n electrons are of very small importance in both qualitative and quantitative drug analysis, the chromophoric groups. The mathematical apparatus necessary for the quantitative treatment of more complex structures characteristic of the majority of pharmaceutical molecules rapidly increases with increasing complexity of the molecules and hence the results of this kind of treatment are hardly accessible for practical analysts. Beside the carbon–carbon double bond the other important chromophoric group of pharmaceutical compounds is the carbonyl group which contains the carbon–oxygen double bond. In order to be familiar with the bases of structure-spectrum relationships some factors have to be briefly discussed which are related to the structural elements in the molecule. The widespread occurrence of aromatic rings among medicinal compounds makes the study of their characteristic light absorption very important for structure-spectra correlations.
