A series of spacer-free ionic azobenzene-containing stoichiometric complexes was prepared from monosulfonated azo dyes and cationic polyelectrolytes [methylated poly(4-vinylpyridine) (PVP) and poly(dimethylaminoethyl methacrylate) (PDM)]. Their thermal and structural characteristics and optical responses, particularly photoinduced birefringence (PIB) and surface relief grating (SRG) inscription, were investigated as a function of selected molecular parameters. All of the complexes have high apparent Tg values, 180−210 °C, and show liquid crystal (LC) order of the single-layer SmA type from ambient to very high temperature, usually to degradation. The range of LC order is greater in the complexes of chromophores with longer alkyl tails and shorter in the complex of the chromophore with an OH end group and the complex of methyl orange (MO) with PDM. PIB, SRG quality, and diffraction efficiency were all shown to depend in a similar way on molecular structural features: the more rigid the molecular structure,...