Water Soluble Cationic Porphyrin Sensor for Detection of Hg2+, Pb2+, Cd2+, and Cu2+

Here we report the sensing properties of the aqueous solution of mesotetra(N-methyl-4-pyridyl)porphine tetrachloride (1) for simultaneous detection of toxic metal ions by using UV-vis spectroscopy. Cationic porphyrin 1 displayed different electronic absorptions in UV-vis region upon interacting with Hg2+, Pb2+, Cd2+, and Cu2+ ions in neutral water solution at room temperature. Quite interestingly, the porphyrin 1 showed that it can function as a single optical chemical sensor and/ or metal ion receptor capable of detecting two or more toxic metal ions, particularly, Hg2+, Pb2+, and Cd2+ ions coexisting in a water sample. Porphyrin 1 in an aqueous solution provides a unique UV-vis sensing system for the determination of Cd2+ in the presence of larger metal ions such as Hg2+, or Pb2+. Finally, the examination of the sensing properties of 1 demonstrated that it can operate as a Cu2+ ion selective sensor via metal displacement from the 1-Hg2+, 1-Pb2+, and 1-Cd2+. INTRODUCTION Determination of metal ions, particularly, Hg2+, Pb2+, Cd2+, and Cu2+ simultaneously by using an inexpensive, water soluble porphyrin based optical sensor has always been a great challenge. In addition, the preparation of porphyrin-based optical sensors often requires complex organic syntheses, which are very costly, and time consuming. PURPOSE RESULTS FUTURE PLAN