Nanosized Porphyrinic Metal–Organic Frameworks for the Construction of Transparent Membranes as a Multiresponsive Optical Gas Sensor

The well-known and excellent colorimetric sensing capacity of porphyrins, along with the exceptional structural properties of metal-organic frameworks (MOFs), make porphyrin-based MOFs, such as PCN-222, ideal candidates for the construction of a chemical sensor based on absorbance. However, to the best of authors' knowledge, no high-quality porphyrin-based MOF gas sensors have been developed to date, most likely due to the difficulties in: 1) preparing nanosized porphyrin-MOFs to minimize scattering in absorbance measurements; and 2) incorporating MOFs into transparent membranes for practical use. Herein, a simple and fast microwave-assisted method for preparing high-quality nanosized PCN-222 crystals and their metalated derivatives PCN-222(M) is reported to finely tune the sensing response. Next, the successful dispersion of these PCN-222(M) nanoparticles into poly(dimethylsiloxane) to create flexible and transparent membranes is demonstrated. This integration yields a multiresponsive optical gas sensor exhibiting excellent sensitivity and the ability to discriminate between various volatile organic compounds via pattern recognition identification.