Bulletin of the Korean Chemical Society

Korean Chemical Society (대한화학회)
권호 표지
DOI QR코드

DOI QR Code

Interaction of the Post-transition Metal Ions and New Macrocycles in Solution

  • Jung, Oh-Jin (Department of Environmental Science, College of Natural Science, Chosun University)
  • Published : 1993.12.20
Download PDF
⟨ Previous Next ⟩

Abstract

Complexation of $Cd^{2+},\;Pb^{2+}\;and\;Hg^{2+}$ ions with four cryptands were studied by potentiometry and solution calorimetry in various weight percent methanol-aqueous solvent at 25${\circ}$C under $CO_2$free nitrogen atmosphere. The stabilities of the complexes were dependent on the cavity size of macrocycles. The $Hg^{2+}$ ion stability constants are higher than those of $Cd^{2+}\;and\;Pb^{2+}$ ion. All the cryptands formed complexes having 1 : 1 (metal to ligand) mole-ratio except for $Hg^{2+}-L_1$ (cryptand 1,2b: 3,5-benzo-9,14,17-trioxa-1,7-diazabicyclo-(8,5,5) heptadecane) and $Cd^{2+}-L_2$ (cryptand 2,2b: 3,5-benzo-10,13,18,21-tetraoxa-1,7-diazabicyclo (8,5,5) eicosane) complexes. $Hg^{2+}-L_1$ complex was a sandwitch type, and the $Cd^{2+}-L_2$ complex showed two stepwise reactions. Thermodynamic parameters of the $Cd^{2+}-L_2$ complex were $6.08(log\;K_1)$, -7.28 Kcal/mol $({\Delta}H_1)$, and $4.78\;(log\;K_2)$, -4.62 Kcal/mol $({\Delta}H_2)$, respectively, for 1 : 1 and 2: 1 mole-ratio. The sequences of the selectivity were increased in the order of $Hg^{2+}\;>Pb^{2+}\;>Cd^{2+}$ ion for $L_3\;and\;L_4$ macrocycles, and the $L_2$-macrocycle has a selectivity for $Cd^{2+}$ ion relative to $Zn^{2+},\;Ni^{2+},\;Pb^{2+}\;and\;Hg^{2+}$ ions. Thus, it is expected that the $L_2$ can be used as carrier for seperation of the post transition metals by macrocycles-mediated liquid membrane because $L_2$ is not soluble in water, and the difference of stability constants of the metal complexes with $L_2$ are large as compared with the other transition metal complexes. The $^1H\;and\;^{13}C-NMR studies indicated that the nitrogen atoms of cryptands have greater affinity to the post transition metal ions than the oxygen atoms, and that the planarities of the macrocycles were lost by complexation with the metal ions because of the perturbation of ring current of benzene molecule attached to macrocycles and counter-anions.

Keywords

References

  1. Cation Binding by Macrocycles Y. Inoue;G. W. Gokel
  2. Inorg. Chem. v.26 A. Bencini;A. Bianchi;E. Garcia-Espana;M. Giusti;S. Mangani;M. Micheloni;P. Orioli;P. Paoletti
  3. J. Chem. Soc. Perkin Trans. v.2 M. Micheloni;P. Paoletti;Avacca
  4. J. Chem. Soc., Perkin Trans. v.2 M. Bartolini;A. Bianchi;M. Micheloni;P. Paoletti
  5. Chem. Rev. v.92 H. Y. An;J. S. Bradshaw;R. M. Izatt
  6. Tetrahedron v.46 J. S. Bradshaw;H-Y An;K. E. Krakowiak;G. Wu;R. M. Izatt
  7. Chem. Rev. v.85 R. M. Izatt;J. S. Bradshaw;S. A. Nielsen;J. D. Lamb;J. J. Christensen
  8. J. Chem. Soc. Dalton Trans. Peter Grans
  9. J. Am. Chem. Soc. v.101 R. M. Izatt;J. D. Lamb;N. E. Izatt;B. E. Jr. Rossiter;J. J. Christensen;B. H. Haymore
  10. Chem. Rev. v.89 R. D. Hancock;A. E. Martell
  11. J. Org. Chem. v.57 E. Krakowiak;J. S. Bradshaw;N. K. Dalley;C. Y. Zhu;Guoliang Yi;J. C. Curtis;Du Li;R. M. Izatt
  12. J. Chem. Soc., Perkin Trans. II B. Metz;D. Moras;R. Weiss
  13. J. Chem. Soc, Dalton Trans. M. Kodama;E. Kimura
  14. J. Chem. Soc, Dalton Trans. M. Kodama;E. Kimura
  15. J. Am. Chem. Soc. v.105 G. W. Gokel;D. M. Goli;C. Miganiti;L. Echegoyen
  16. J. Am. Chem. Soc. v.93 H. K. Frendorf
  17. J. Chem. Soc., Dalton Trans. P. Gans;A. Sebatini;A. Vacca
  18. J. Incl. Phenom. v.7 M. Pietraskiewicz;R. Gassiorouwski;J. Kozbial