Perchlorate anion on manganese(III) porphyrin as an ATR-IR probe for nanoscopic water environments

The effects of aqueous environments on the perchlorate infrared lineshape were investigated in various ionic solutions, including a polymeric polyvinyl chloride membrane and perchlorate coordinated to manganese(III) porphyrin, using the model frequency–frequency correlation function (FFCF). The perchlorate ligand moiety is considered a useful infrared probe in aqueous nanoscopic environments. We observed an asymmetric mode of the ligated perchlorate, in which the lineshape had a smaller bandwidth and faster dynamics than that of a 1 M perchlorate aqueous solution. In the 6 M solutions, we observed at least two conformations with faster dynamics than that of the 1 M solution, regardless of whether it was in the heterogeneous polymer matrix.