Assessment of photosensitization performance and stability of host-guest MCM-41 composites from the direct observation of singlet oxygen formation and properties

International audienceNew heterogeneous porous materials based on 5,10,15,20-(tetraphenyl)porphyrin (H 2 TPP), 5,10,15,20-(tetra-N-methyl-4-pyridyl)porphyrin tetrachloride (H 2 TNMPyP), zinc(II) 5,10,15,20-(tetra-N-methyl-4-pyridyl)porphyrin tetrachloride (ZnTNMP y P), 5,10,15,20-(tetra-4-carboxyphenyl)porphyrin (H 2 TCPP) and zinc(II)5,10,15,20-(tetra-4-carboxyphenyl)porphyrin (ZnTCPP) have been incorporated into mesoporous silica MCM-41 from slow diffusion of solutions containing different concentrations of porphyrin chromophores. Successful incorporation of all porphyrins has been confirmed by UV-Vis spectroscopy and TGA. XRD patterns of these silica-based host-guest samples prove that the mesoporous structure of MCM-41 remains unchanged after encapsulation. The potential abilities of these photosensitizers to form singlet oxygen ( 1 O[Formula: see text] at the solid state/air interface after light excitation were investigated. Despite the variable amount of encapsulated porphyrin derivatives (based on UV-vis assessment and chemical analysis), the phosphorescence intensity of 1 O 2 peak at 1270 nm remains relatively the same from one composite to the other meaning that the photosensitizers are mainly placed at the surface of the MCM-41 particles