Metallation-Demetallation Reaction of Tin Tetra(4-Pyridyl) Porphyrin in Na-Hectorite

Abstract

Abstract The adsorption of Sn(IV)TPyP (mesotetrapyridylporphyrin) in sodium hectorite was studied using ultraviolet-visible and luminescence spectroscopy. The adsorbed complex was found to demetallate forming the TPyP dication as the clay is dehydrated. This process was found to be reversible indicating that the Sn 4+ ion remains in the vicinity of the porphyrin upon demetallation. The luminescence spectrum of the adsorbed complex was found to be a composite of the Sn(IV)TPyP and the dication spectra. The presence of a band at 750 nm in the luminescence spectrum of the adsorbed species suggested an enhanced interaction between the π -systems of the pyridyl substituents and the porphin nucleus. This is believed to result from a decrease in the dihedral angle between the nucleus and the substituents when they are squeezed between the clay sheets.