Synthesis and spectroscopy of clay intercalated Cu(II) bio-monomer complexes: coordination of Cu(II) with purines and nucleotides

Abstract

The spectroscopic properties of Cu(bio-monomer)_n^m+ complexes [BM=bio-monomer (purine, adenine, guanine, hypoxanthine, 5′-ADP and 5′-GMP)] in saponite clays have been investigated by diffuse reflectance spectroscopy (DRS) in the UV-Vis-NIR region and electron paramagnetic resonance (EPR) at X-band. Mono- and/or bis complexes of Cu(purine), Cu(adenine), Cu(5′-ADP) and Cu(5′-GMP) have been intercalated between the layers of saponite by a simple cation exchange procedure from aqueous solutions of pre-formed Cu(BM)_n^m+ complexes. Successful immobilisation was obtained with a BM:Cu²⁺ ratio of 5, but the exact coordination geometry of the intercalated complexes was determined by the overall Cu-loading, the pH of the initial exchange solution and the type of BM. Mono Cu(adenine) and Cu(purine) complexes with a NNOO coordination dominate at low Cu-loadings, or at an exchange solution pH between 3 and 4, whereas bis Cu(adenine)₂²⁺ and Cu(purine)₂²⁺ complexes with a NNNN coordination are exclusively present at higher Cu-loadingswithanexchangesolutionpHbetween5and8.Ontheotherhand, clay-intercalated Cu(5′-ADP)⁺ and Cu(5′-GMP)⁺ are always present as mono-complexes, most probably in a NOOO coordination.

References

1. P. Liebmann, G. Loew, S. Burt, J. Lawless and R. D. MacElroy, Inorg. Chem., 1982, 21, 1586.
2. E.g. R. Lohrmann, P. K. Bridson and L. E. Orgel, Science, 1980, 208, 1464; B. J. Weimann, R. Lohrmann, L. E. Orgel, H. Schneider-Bernloehr and J. E. Sulston, Science, 1968, 161, 387.
3. (a) J. D. Bernal, The physical basis of life, Routledge and Kegan Paul, London, 1951; (b) P. Laszlo, Science, 1987, 235, 1473.
4. N. Lahav and S. Chang, J. Mol. Evol., 1976, 8, 357.
5. B. K. G. Theng, The chemistry of clay-organic reactions, Wiley, New York, 1974.
6. M. Paecht-Horowitz, J. Berger and A. Katchalsky, Nature (London), 1970, 228, 636.
7. M. Paecht-Horowitz, Isr. J. Chem., 1973, 11, 369.
8. V. A. Ostroschenko and N. V. Vasilyeva, Origins Life, 1977, 8, 25.
9. G. E. Lailach, T. D. Thompson and G. W. Brindley, Clays Clay Miner., 1968, 16, 285.
10. G. E. Lailach, T. D. Thompson and G. W. Brindley, Clays Clay Miner., 1968, 16, 295.
11. G. E. Lailach and G. W. Brindley, Clays Clay Miner., 1969, 17, 95.
12. T. D. Thompson and G. W. Brindley, Am. Mineral., 1969, 54, 858.
13. J. P. Ferris and G. Ertem, J. Am. Chem. Soc., 1993, 115, 12270.
14. J. G. Lawless and E. H. Edelson, in COSPAR Life Sciences and Space Research, ed. R. Holmquist, Pergamon Press, New York, 1983, p. 83.
15. M. M. Mortland and J. G. Lawless, Clays Clay Miner., 1983, 31, 435.
16. M. M. Mortland, J. G. Lawless, H. Hartman and R. Frankel, Clays Clay Miner., 1984, 32, 279.
17. N. J. Clayden and J. S. Waugh, J. Chem. Soc., Chem. Commun., 1983, 292.
18. B. M. Weckhuysen, A. A. Verberckmoes, I. P. Vannijvel, J. A. Pelgrims, P. L. Buskens, P. A. Jacobs and R. A. Schoonheydt, Angew. Chem. Int. Ed. Engl., 1995, 34, 2652.
19. L. Fu, B. M. Weckhuysen, A. A. Verberckmoes and R. A. Schoonheydt, Clay Miner., 1996, 31, 491.
20. B. M. Weckhuysen, A. A. Verberckmoes, L. Fu and R. A. Schoonheydt, J. Phys. Chem., 1996, 100, 9456.
21. D. Goldfarb, Y. Gao, P. Manikandan, T. Shane, J. J. Shane, B. M. Weckhuysen, H. Leeman and R. A. Schoonheydt, J. Am. Chem. Soc., submitted for publication.
22. T. R. Harkins and H. Freiser, J. Am. Chem. Soc., 1958, 80, 1132.
23. G. E. Cheney, H. Freiser and Q. Fernando, J. Am. Chem. Soc., 1959, 81, 2611.
24. R. Weiss and H. Venner, Z. Physiol. Chem., 1965, 340, 138.