ADSORPTION OF THYMINE AND URACIL ON MERCURY AND TUNGSTEN FERROCYANIDES AND ITS IMPLICATION IN CHEMICAL EVOLUTION
Brij Bhushan Tewari*and Rayanna A. Whyte
Department of Chemistry, University of Guyana, P. O. Box: 101110, Georgetown, Guyana
*Presenter e - mail: brij.tewari@uog.edu.gy
It is thought that the metal-cyano complexes were produced on primitive earth due to interaction of cyanides with metal ions present in primeval seas. These metal cyano complexes acted as adsorbents, ion exchangers and photosensitizers .Adsorption of thymine and uracil on mercury and tungsten ferrocyanides has been studied at pH range 1.0 – 10.0 and a temperature of 30 ± 10 C. The progress of adsorption was followed spectrophotometrically by measuring the absorbance of nucleic acid bases at their corresponding λmax. The Langmuir type of adsorption is followed in the concentration range 10- 4 to 10- 5 Mol L-1 of thymine and uracil solutions. At neutral pH thymine was found to be more adsorbed than uracil on both adsorbents, this may be due to presence of methyl group and tautomeric (keto and enol) form of the thymine. Mercury ferrocyanide was found to have more uptake capacity of nucleic acid bases in comparison to tungsten ferrocyanides. Studies on effect of metal salts on adsorption of nucleic acid bases on metal ferrocyanides confirm the assumption that at normal condition adsorption is due to interaction of nucleic acid base with metal ions present out of coordination sphere of metal ferrocyanides. Present study suggest the importance of possible prebiotic mineral (metal ferrocyanides) in concentrating bio-monomers from dilute prebiotic soup, during the course of chemical evolution on primitive earth.
Keywords: Adsorption, thymine, uracil, prebiotic mineral, metal ferrocyanides, chemical evolution.
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