Copolyformals containing metalloporphyrins as solid optical probes for amines detection

A polymer-based sensor incorporating porphyrin species as the sensing unit, which makes it able to detect different volatile organic compounds (VOCs) of environmental and industrial relevance, was developed by synthesizing copolyetherformals with metalloporphyrin units in the main chain. Particularly, the Zinc and Cobalt -porphyrins were produced by metalation of the porphyrin moiety into the copolyetherformal. The structural and chemical-physical features of the obtained systems were investigated by means of MALDI-TOF mass spectrometry, gel permeation chromatography, UV–Vis, fluorescence and nuclear magnetic resonance spectroscopies, as well as thermoanalyses techniques. The sensing properties of the copolymers were evaluated in toluene solutions and in solid-state thin film. In solution, the zinc-porphyrin-containing copolymer exhibited a linear response in the range of 60 μM to 0.7 mM for pyridine and approximately 1.1 μM–60 μM for piperidine. The cobalt-porphyrin-containing copolymer exhibited a linear response in the range of approximately 0.3 μM–30 μM for pyridine and about 0.09 μM–18 μM for piperidine. The performance of the sensors was further investigated in the solid state by exposing the thin films of the copolymer sensors to VOCs, showing sensing features towards the amine species and no sensing activity towards the ethers and aromatic nonpolar species. These findings underline the potential of metalloporphyrin-polymeric systems as versatile and highly sensitive materials for VOCs optical sensing applications.