Optical pH Meter by Means of a Porphyrin Monolayer Covalently Assembled on a Molecularly Engineered Silica Surface

Abstract

The evolution of the UV−vis absorbance spectra of a new porphyrin covalently assembled monolayer, upon immersion in increasing [H3O+] solutions, showed the disappearing of the Soret band and the progressive increase of a new band. A few seconds of H2O washing and drying under a N2 gas stream totally recovers the starting Soret. Therefore, the system represents a well-suited fast and reversible solid optical pH meter.