A nove, heterogeneous approach to "naked-eye" colorimetric and spectrophotometric anion sensing is demonstrated, employing the molecular receptor alizarin complexone adsorbed onto a nanocrystalline, mesoporous TiO2 film. pH buffer action intrinsic to the TiO2 film allows dip sensing in aqueous solutions. This heterogeneous sensing system exhibits a high selectivity to F- and CN- anions, high sensitivity, a rapid response time, and excellent reusability.