Crystal Structures of H-Aggregate of Azobenzene-Containing Amphiphiles, C6AzoC8N+ Br− and C8AzoC10N+ Br−

Abstract

The molecular and packing structures of H-aggregates of azobenzene-containing amphiphiles, C₆AzoC₈N⁺Br⁻ and C₈AzoC₁₀N ⁺ Br⁻, have been determined by X-ray single crystal analyses. Both crystals belong to the monoclinic system with the space group P2₁ and Z = 2. The unit cell dimensions of the former crystal are a = 34.04(7), b = 7.468(2), c = 5.967(1) Å, β = 94.67(3)˚. Those of the latter are a = 38.81(2), b = 7.451(1), c = 5.936(1) Å, β = 97.56(3)˚. Molecular and crystal structures of these two compounds are quite similar. Molecules are packed laterally to form a monolayer structure. Therefore, two hydrophobic chains are arranged in the antiparallel fashion and interdigitated mutually. Contrary to the expectation for the H-aggregates, a fairly large inclination angle (ca. 65˚) was observed between the planes of the neighboring azobenzene chromophores.