ROLE OF TRANSITION-METAL FERROCYANIDES(II) IN CHEMICAL EVOLUTION

Due to ease of formation of cyanide under prebiotic conditions, cyanide ion might have formed stable complexes with transition metal ions on the primitive earth. In the course of chemical evolution insoluble metal cyano complexes, which settled at the bottom of primeval sea could have formed peptide and metal amino acid complexes through adsorption processes of amino acids onto these metal cyano complexes. Adsorption of amino acids such as glycine, aspartic acid, and histidine on copper ferrocyanide and zinc ferrocyanide have been studied over a wide pH range of 3.6 - 8.5. Amino acids were adsorbed on the metal ferrocyanide complexes for different time periods. The progress of the adsorption was followed spectro-photometrically using ninhydrin reagent. Histidine was found to show maximum adsorption on both the adsorbents at neutral pH. Zinc ferrocyanide exhibits good sorption behaviour for all the three amino acids used in these investigations. © 1990 Kluwer Academic Publishers.