Cobalt(II) Coordination Compounds of Ethyl 4-Methyl-5-Imidazolecarboxylate: Chemical and Biochemical Characterization on Photosynthesis and Seed Germination

Abstract

In this work we present the synthesis, structural and spectroscopic characterization of Co2+coordination compounds with ethyl 4-methyl-5-imidazolecarboxylate (emizco). The effects of emizco, the metal saltsCoCl2.6H2O,CoBr2,Co(NO3)2.6H2Oand their metal coordination compounds[Co(emizco)2Cl2],[Co(emizco)2Br2].H2O,[Co(emizco)2(H2O)2](NO3)2.2H2Owere evaluated on photosynthesis in spinach chloroplasts. Seed germination and seedling growth of the monocotyledonous speciesLolium multiflorumandTriticum aestivumand the dicotyledonous speciesTrifolium alexandrinumandPhysalis ixocarpawere also assayed under the effect of the compounds and salts. The results showed that cobalt(II) salts and their emizco coordination compounds inhibit photosynthetic electron flow and ATP-synthesis, behaving as Hill reaction inhibitors. Coordination compounds are more potent inhibitors than the salts. It was found that the salts target is at the b6f level while the complexes targets are at QB(D1)-protein and b6f level. The QBinhibition site was confirmed by variable chlorophyllafluorescence yield. On the other hand, emizco inhibits seed germination, root and shoot development, in both weed and crop species. Cobalt(II) coordination compounds are the most effective photosynthesis inhibitors, but they are less potent than emizco in germination and seedling growth, while the metal salts are the least active of all.