Spectrophotometric investigation of the interactions between cationic porphyrazine and different anionic surfactants

Interactions between tetrakis(N, N', N '', N"'-tetramethyl tetra-2,3-pridino) porphyrazine copper(II) (Cu(tmtppa)) with anionic surfactants: sodium dodecyl sulfate (SDS), sodium tetradecyl sulfonate (STS) and sodium hexadecyl sulfonate (SHS) were investigated in aqueous submicellar solutions using spectrophotometric method at 298.15, 303.15, 313.15, 318.15 and 323.15 K. Binding constants between the submicellar solutions of surfactants and Cu(tmtppa) system were calculated from the changes in absorbance values at different temperatures. The results showed that increasing alkyl chain length of surfactants caused a stronger interaction indicating the importance of hydrophobic forces. It was found that the values of binding constant increased with increasing temperature. Thermodynamic parameters (Delta G degrees, Delta H degrees and Delta S degrees) were determined for the binding processes of porphyrazine-surfactant system. It was concluded from Delta G degrees and Delta H degrees values that the binding process occurred spontaneously and was endothermic in nature.