Colorimetric responses of transparent polymers doped with metal phthalocyanine for detecting vaporous amines

This paper reports colorimetric responses of several metal phthalocyanines (MPcs), and MPc-doped polymers to primary amines. Among all MPcs tested, only FePc shows promise as a good candidate for detecting primary amines. In toluene, FePc shows a distinct color change from colorless to deep green upon addition of hexylamine. This colorimetric response is also highly specific. FePc does not respond to secondary amines, tertiary amines or other interferents tested in the study. We also doped several transparent polymers, poly(vinylalcohol) (PVA), Norland Optical Adhesive 65 (NOA65), and poly(dimethylsiloxane) with FePc and studied their colorimetric responses to hexylamine. Although they all exhibit color changes from transparent to green upon exposure to hexylamine, we find that only PDMS doped with FePc shows a selective and reversible response to hexylamine. Thus, FePc-doped PDMS may be coated onto protective suits or safety goggles to offer real-time information about amine exposure.