Assessment of a chromogenic calix[4]arene for the rapid colorimetric detection of trimethylamine

A calix[4]arene bearing nitrophenylazophenol chromogenic moieties when complexed with lithium has been synthesized and examined as a visual indicator for the presence of gaseous amines such as trimethylamine (TMA). The complexed calixarene has been immobilised onto filter paper and found to undergo a dramatic colour change from yellow to red in the presence of gaseous TMA at concentrations above 20 ppb in under 2 min. The intensity of the colour produced is TMA-concentration dependent.