Mesoporous SBA-15 silica impregnated with Reichardt’s dye: a material optically responding to NH3

SBA-15 mesoporous silica system impregnated with Reichardt’s dye is white if still covered with hydroxyls; a pink colouration is observed by exposing the sample to NH3 and primary amines. The process is fully reversible. The mechanism of colour change is discussed, and such systems are proposed as possible ammonia sensors.