Chlorosomal Self-aggregation of Zinc Chlorophyll Derivatives in the Presence of Cationic Surfactant Cetyltrimethylammonium Bromide and Organosilanes in Aqueous Phase

Abstract

Self-aggregation of zinc methyl 3-devinyl-3-hydroxymethyl-pyropheophorbide a (zinc chlorin 1) was examined in the presence of a cationic surfactant cetyltrimethylammonium bromide (CTAB) and three kinds of organosilanes (tetraethoxysilane (TEOS), ethyltrichlorosilane (ETCS), and butyltrichlorosilane (BTCS) in water to construct stable supramolecules mimicking chlorosomes by sol-gel processes. Zinc chlorin 1 with CTAB and TEOS exhibited red-shifted Soret and Qy bands compared with monomeric 1, and large CD signals were observed in the Soret and Qy region. These indicate that zinc chlorin 1 can form chlorosomal self-aggregates in the presence of CTAB and TEOS. In contrast, addition of a methanol solution of ETCS and BTCS to the aqueous solution of self-aggregates of 1 in CTAB micelles caused their disaggregation.