A Polarographic Study of Tl
+
, Pb
2
and Cd
2+
Complexes with Dicyclohexano-18-Crown-6 in Some Binary Mixed Solvents |
| |
| Authors: | Gholamhossein Rounaghi Ali Sarafraz Yazdi Zahra Monsef |
| |
| Institution: | (1) Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran |
| |
| Abstract: | The complexes of Tl+, Pb2+ and Cd2+ cations with the macrocyclic ligand, dicyclohexano-18-crown-6\linebreak(DC18C6) were studied in water/methanol (H2+O/MeOH), water/1-propanol (H2+O/1-PrOH), water/acetonitrile (H2+O/AN), water/dimethylformamide (H2+O/DMF), dimethylformamide/acetonitrile (DMF/AN), dimethylformamide/methanol (DMF/MeOH), dimethylformamide/1-propanol (DMF/1-PrOH) and dimethylformamide/nitromethane (DMF/NM) mixed solvents at 22 °C using differential pulse polarography (DPP), square wave polarography and conductometry. In general, the stability of the complexes was found to decrease with increasing concentration of water in aqueous/non-aqueous mixed solvents with an inverse relationship between the stability constants of the complexes and the concentration of DMF in non-aqueous mixed solvents. The results show that the change in stability of DC18C6.Tl+, vs the composition of solvent in DMF/AN and DMF/NM mixed solvents is apparently different from that in DMF/MeOH and DMF/1-PrOH mixed solvents. While the variation of stability constants of the DC18C6.Tl+ and DC18C6.Pb2+ complexes vs the composition of H2+O/AN mixed solvents is monotonic, an anomalous behavior was observed for variations of log Kf vs the composition of H2+O/1-PrOH and H2+O/MeOH mixed solvents. The selectivity order of the DC18C6 ligand for the cations was found to be Pb2+ > Tl+ > Cd2+. |
| |
| Keywords: | dicyclohexano-18-crown-6 Pb2+ Tl+ Cd2+ mixed solvents polarography metal complexes stability constants |
| 本文献已被 SpringerLink 等数据库收录！ |
|
