Effect of the chelate ring size of diamine-Co(III) complexes on their hR(F) values obtained under salting-out thin-layer chromatography conditions

The effect of the chelate ring size of diamine Co(III) complexes under salting-out thin-layer chromatography (TLC) conditions was investigated. For that purpose, 16 neutral and cationic complexes containing from five- to seven-membered diamine chelate rings were chromatographed on the thin layers of silica gel, cellulose and polyacrylonitrile sorbents. Six aqueous solutions of ammonium sulphate at various concentrations were used as solvent systems. In all of the instances studied, it was established that hR(F) values decrease with increasing ring size. It was also found that the R-M Values obtained were a linear function; on the one side, salt concentrations in the chromatographic solvent systems used, and on the other side the diamine chelate ring size. To explain these results, a mechanism based on hydrophobic interaction between the sorbend and sorbent is proposed. (C) 1999 Elsevier Science B.V. All rights reserved