Tuning of the sensing abilities of certain chromogenic molecules is achieved by anchoring them to modified MCM-41-type solids. This approach allows chromogenic detection of primary aliphatic amines of a certain length in water. The Figure shows color changes of the functionalized solid (magenta-yellow) in the presence of n-heptylamine, n-octylamine, and n-nonylamine. Longer or shorter aliphatic chains induced no significant color variation.