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| Titel: |
Cu(II), Zn(II), AND Pb(II) STABILITY CONSTANTS OF CYCLAM AMPHIPHILES |
| Auteur: |
Puranik, Dhananjay B. Singh, Alok Chang, Eddie L. |
| Verschenen in: |
Journal of coordination chemistry |
| Paginering: | Jaargang 39 (1996) nr. 3-4 pagina's 321-331 |
| Jaar: |
1996-11-01 |
| Inhoud: |
1-Hexadecyl-1,4,8,11-tetraazacyclotetradecane (hexadecyl cyclam) and 1-(3,7,11,15-tetramethyl) hexadecyl-1,4,8,11-tetraazacyclotetradecane (tetramethylhexadecyl cyclam) have been synthesized and their deprotonation and ligand-metal formation constants, K, determined for Cu(II), Zn(II) and Pb(II). The coupling of a long hydrocarbon chain to a ring nitrogen decreased the general ability of the cyclam ring to complex with metal ions. The greatest effect appeared to be for Cu(II) decreasing from a pK of 27 for cyclam to about 17. The titrations were fitted by HYPERQUAD and the concentrations of the intermediate complexes obtained as a function of pH. Metal-ligand complexes LMH24+, LMH2+ and LM2+ can coexist through a wide pH range. We have also calculated a composite metal-binding constant, K', to reflect more accurately the overall ability of these ligands to bind a metal at any particular pH. K', which is 14.6 for (hexadecyl cyclam)-Cu(II), is constructed from the concentrations of all the metal-chelated species at pH = 7. Generally, K' is much lower than K. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 24 van 116 gevonden artikelen
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