A family of solid-state, inorganic compounds known as zirconium phosphonates, Zr(O₃PR)₂, possess a layered structure in which the attractive interactions of the R groups that project into the interlayer region (above and below any given zirconium layer) are responsible for the plane-stacking motif. Mixed phosphonates in which two different pendant groups are incorporated [Zr(O₃PR)_x(O₃PR)_2-x] possess interesting structural and optical properties. A number of materials, in which the pendant groups include both alkyl and arene moieties, have been synthesized and characterized (using thermal gravimetric analysis, IR, and solid-state ³¹P NMR). The interlayer spacings as a function of stoichiometric ratio R:R' were measured using X-ray powder diffraction. Corroboration of the experimental results, and insight into the structural features underlying them, were obtained via molecular mechanics calculations. Results reveal that there are three structural-behavior classes when considering interlayer spacing as a function of large-group content: uniform, single-stepped, and double-stepped. Also, the photophysical properties of a number of compounds were investigated using absorbance and fluorescence spectroscopies. Results will be presented that demonstrate the presence of both excimer formation and energy transfer among the chromophore pendant groups.