To determine optimum conditions for large photoresponses, the alkyl chain length and the concentration of trimethyl-alkylammonium (TMAA) were varied to prepare 16 o-TSM hosts for organophilic fluor-tetrasilicic mica (o-TSM) I azobenzene (AzBz) complexes. Photoresponses for AzBz/o-TSM complexes prepared by vapor-phase intercalation of AzBz into o-TSM were monitored by changes in d(001) under UV irradiation (lambda = 365 nm). A large photoresponse, a 0.2-0.5 nm decrease in d(001), was observed for the complexes with o-TSM hosts having a pseudo-trimolecular structure with 2.2-2.5 nm basal spacing. The complexes with less or no photoresponse were derived from o-TSM with bimolecular and paraffin-type structures. These results indicate that photoresponsiveness is closely related to the structure of the o-TSM hosts, and that pseudo-trimolecular-structure o-TSM can provide complexes with good photoresponsive properties.