Interaction of Fe(III) Tetrakis(4-N-methylpyridinium)porphyrin with Sodium Dodecyl Sulfate at Submicellar Concentrations
Interaction of water soluble Fe(III) tetrakis(4-N-methylpyridinium)porphyrin (Fe(III)TMPyP) with sodium dodecyl sulfate (SDS) in submicellar concentrations has been studied by surface tension, optical absorption, resonance light scattering (RLS), ζ-potential, and energy dispersive X-ray spectroscopy (EDS) measurements. Measurements were conducted for a fixed concentration of Fe(III)TMPyP (6 × 10−5 M) and SDS in various concentrations ranging between 6 × 10−6 and 6 × 10−2 M. Two macroscopic phase transitions, precipitation and redissolution, were observed as function of SDS concentration. The presence of a new surface active porphyrin−surfactant complex was detected. Furthermore, the presence of two oppositely charged Fe(III)TMPyP−SDS bulk moieties has been demonstrated. Possible structures for the different moieties are suggested, and the phase transitions are discussed.