Clays, porphyrin intercalation into

Clays are colloidal layered hydrous aluminosilicates. There are relatively few examples of porphyrin intercalation into clays reported, mostly with either smectite clays or layered double hydroxides (LDH). Smectite clays consist of negatively charged layered aluminosilicate sheets. These sheets are separated by cations and water molecules. The... 

Another approach was to intercalate metalloporphyrins into layered minerals such as clays 19. For instance, the tetracationic Mn(TMPyP = meso-tetra-N-methyl-pyridiniumyl porphyrin) catalyst was intercalated into the interlayer space of montmorillonite by simple ion exchange with already present cations 23. The corresponding supported catalyst was found to be much more efficient for hydroxylation of heptane by PhIO than the same Mn-porphyrin either simply... 

Porphyrins were first introduced into clays in 1977 by the physical absorption of porphyrin molecules into montmor-illonite in aqueous solutions." The most common examples are the binding of tetracationic M(TMPyP) porphyrins, M = Co(II), Mn(III), Fe(III), into montmor-illonite clays. Co(TMPyP) was the first porphyrin to be intercalated into montmorillonite by ion exchange in acid solution. The interlayer distance expanded from 27 to 37 A upon intercalation. UV-visible studies revealed the retention of cobalt ions in the porphyrin molecules. Mansuy and coworkers have extended this approach and prepared the Mn-porphyrin intercalated materials. These solids are efficient alkene epoxidation and alkane hydroxylation catalysts." Additionally, the catalyst exhibited a marked shape selectivity in favor of small linear alkanes when compared to more bulky substrates. It was also shown that... 

Another method for the intercalation of metalloporphy-rins into clays has been explored using porphyrins and metalloporphyrins as organic templates in the hydrothermal synthesis of layered silicates. X-ray powder-diffraction data indicate that the porphyrins are intercalated parallel to the silicate layers. Microanalysis and UV-visible diffuse-reflectance spectra indicate that the porphyrins are incorporated intact. 

---