Aggregation, Complexation with Guest Molecules, and Mesomorphism of Amphiphilic Phthalocyanines Having Four- or Eight Tri(ethylene oxide) Chains

Abstract

Abstract Zinc and metal-free amphiphilic phthalocyanines (pcs) substituted by four or eight tri(ethylene oxide) chains (3,6,9-trioxadecyloxy groups) {(H2(4EGpc), [Zn(4EGpc)], H2(8EGpc), and [Zn(8EGpc)] in Fig. 1)} have been prepared in order to study their aggregation in water, dioxane, and dioxane/water mixtures, their complexation phenomena with guest molecules in benzene, and mesomorphism in the neat state. In particular, tetra-substituted pcs have C4h symmetry and do not contain other positional isomers. [Zn(8EGpc)] forms aggregates in water and water–organic solvent mixtures; the extent of this was examined by electronic absorption and fluorescence spectroscopy. 1H NMR and fluorescence spectroscopy indicated that H2- and [Zn(8EGpc)] form inclusion complexes with quinones in benzene via hydrogen bonding. Benzoquinones with more hydroxy groups form complexes more effectively, plausibly laterally outside of the pc plane. From the higher field shift of the 1H singals of 2,2′-dihydroxy-1,1′-binaphthyl (BINAP) in the presence of [Zn(8EGpc)], BINAP molecules were suggested to lie above or below the pc plane. The mesomorphism of H2(8EGpc), [Zn(4EGpc)], and H2(4EGpc) was studied. In the case of H2(8EGpc), the discotic hexagonal ordered columnar (Dho) phase was seen in the range of from room temperature to 265 °C. However, liquid-crystalline phases were not observed for H2(4EGpc) and [Zn(4EGpc)].