Crystallization of Palladium(II)-Pyridylazophenol Complex at the Liquid-Liquid Interface

The crystallization of the palladium(II) complex with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (HL) at the liquid-liquid interface was investigated in the heptane-toluene mixture/water system. Interfacial crystallization of PdLCl did not occur in the heptane/water system, whereas it occurred in the heptane-toluene mixture/water system. The crystal size distribution of PdLCl formed at the liquid-liquid interface strongly depended on the PdLCl solubility in the organic phase and the formation rate. Larger PdLCl crystals formed at the liquid-liquid interface under the higher toluene ratio, higher Pd(II) concentration and lower pH conditions.