Self-reporting materials: Dual use for porphyrin-embedded sorbents

A previous effort demonstrated the utility of porphyrin functionalized organosilicate sorbents in the removal of phosgene. The current study sought to characterize the spectrophotometric response of the sorbents during their application to determine the potential for dual use in both removal of phosgene and reporting on phosgene exposure. The effort is intended as a first step toward using the materials for self-reporting or residual life indication. An ethane bridged silica was functionalized using deuteroporphyrin IX 2,4 bis-ethylene glycol. Several metalloporphyrin variants were generated based on this porphyrin functionalized sorbent, and fluorescence characteristics were evaluated in the prior to and following exposure to phosgene. Reflectance characteristics and changes upon target exposure were also evaluated. Cu, Mg, and Zn sorbents showed the most significant changes upon exposure to phosgene. The reflectance characteristics of these sorbents were evaluated across a range of loading levels for sorbent columns to the point of complete target breakthrough. The results indicate the possibility for reflectance or visual inspection based end-of-life indication for these sorbents.