Thermal Studies of Aqueous Free-base Porphyrin andMetalloporphyrins of Trivalent and Tetravalent Metal Ions

The free-base porphyrin and metalloporphyrins of Fe (monomer), Fe (dimer) and Sn (tin) were synthesized and purified by dry column chromatography. Aqueous free-base porphyrin and metalloporphyrins were characterized by UV-visible spectroscopy, IR spectroscopy and high-resolution mass spectrometry. Further, these synthesized porphyrins were subjected to TG-DSC anlysis from room temperature to 800 ºC. It was observed that each porphyrin has a characteristic first decomposition temperature and their thermal stabilities varied from 360-432 ºC. Since, these aqueous porphyrins are highly hygroscopic in nature, their number of waters of crystallization were determined.