We have intercalated Cr(en)(3)(3+) and Co(en)(3)(3+) molecules (en = ethylenediamine), in known solid-solution fractional quantities, into the highly purified layered alumino-silicate fluorohectorite. Both molecules have like chemistry, but different physical sizes as they function to prop open the interlamellar gallery. As the fractional component x in [Co(en)(3)(3+)](x)[Cr(en)(3)(3+)] (1-x)- fluorohectorite is systematically varied, we observe the effect of intercalation on the host crystal basal spacing and the effects of intercalation on the guest molecules. Typical of the intercalation of rigid-layer compounds with agents differing in size, the basal spacing shows a sigmoidal dependence on fractional concentration. This is due to the large, but not infinite rigidity of the host and guest constituents. The lifetime of the fluorescence emission from the Cr(en)(3)(3+) molecule exhibits the same sigmoidal dependence, indicating that the uniaxial stress exerted on the molecule, as it props open the gallery, is the primary factor dictating the guest fluorescence properties.