Electric Spectra Study of Tetra-Hydrophenyl Porphyrin with Two Hexadecyl Chains in CTAB Micelle Aqueous Solutions

Abstract

UV-visible and fluorescence spectral studies shows that tetra-hydrophenyl porphyrin with two hexadecyl chains (P₂) could be solubilized in CTAB micelle, and that the hydrophilic ability of P2 increases with increasing bulk pH. The change in bulk pH lead to the changing of the solubilizing location of P₂ in the CTAB micelle. In neutral (pH 6.88) conditions, the hydrophilic head group of P₂ readily locates in the stern layer of CTAB micelle. However, the solubilizing location of P₂ takes a location change to the outer surface of the CTAB micelle with the bulk pH increasing up to 11.41. Furthermore, the CTAB micelle could provide a strong basic microenvironment (like 1.5 mol dm⁻³ NaOH aqueous solution) to P₂ in mild basic conditions; resulting in the deprotonation of the pyrrole nitrogen of the porphyrin moiety in a mile basic CTAB micelle solution.

Key Words:

• electric spectra
• porphyrin
• CTAB
• micelle.