Changes in physiological activity of algae Desmodesmus quadricauda after active bioaccumulation of newly prepared and characterized Fe(III) complexes with pyridine-3-carboxamide (pca) by living algal cells

The study characterized five iron(III) complexes with heterocyclic N-donor ligand pyridine-3-carboxamide (pca) [FeCl3(pca)3], [Fe(H2O)2(pca)3](ClO4)3, [Fe2O(ac)2(pca)6]Cl2·3H2O, [Fe(NO3)3(pca)3]·3H2O, [Fe(Cl2ac)3(pca)3] (ac = acetate, Cl2ac = dichloroacetate) and their effects on biomass, chlorophylls (a, b), photosynthetic oxygen production and iron biosorption in algae Desmodesmus quadricauda. The effects of Fe(III) complexes were compared with control and those of FeCl3·6H2O. While pca coordination to iron atom through the nitrogen atom of its heterocyclic ring mostly increased iron inhibitory effect on algal biomass and chlorophylls production, oxygen production was enhanced. The exceptions were observed only for [Fe2O(ac)2(pca)6]Cl2·3H2O complex effect on biomass and oxygen production and [Fe(H2O)2(pca)3](ClO4)3 complex effect on chlorophylls production. Complexation increased iron biosorption in algal biomass and iron accumulated amount in algae was 2.8–20 times higher than that from FeCl3·6H2O with maximal accumulation from dimeric complex [Fe2O(ac)2(pca)6]Cl2·3H2O.