The influence of halogens on the electronic system of biologically important ligands: spectroscopic study of halogenobenzoic acids, halogenobenzoates and 5-halogenouracils

Halogenobenzoates and 5-halogenouracils are commonly applied in industrial and medical fields. From this point of view, it is very important to study the effect of halogens and metal on the above mentioned biologically important ligands. This paper reviews the results of many years’ studies on the influence of halogens (in the series: F → Cl → Br → I) on the electronic system of benzoic acid and uracil. Moreover, the effect of metals (in the series: Mg → Ca → Sr → Ba ; Li → Na → K; in the long series of lanthanide elements: La(III) → Lu(III) except Pm) on the electronic charge distribution in halogenobenzoates is discussed. Systematic changes in the spectra of studied compounds were found. It allowed us to say that ionic potential and electronegativity of elements are the main parameters deciding on the electronic charge distribution in the molecule. Different complementary spectroscopic and quantum-chemical methods were applied in the study.