Cobalt ortho- and para-substituted tetraphenylporphyrins inserted in SiO2 gels

Fluorescent tetraruthenated porphyrins embedded in monolithic SiO2 gels by the sol–gel process

“…For Co(3-TRPyP) it can be emphasized that the similarity between the ethanolic solution spectrum and the spectrum of the porphyrin in the gel indicates that the four electrochemically active sites have not suffered redox reactions during the material preparation, which, however, should be confirmed by spectroelectrochemistry studies. The observation of an absorption spectrum similar to the solution spectrum also evidences the absence of demetallation, in contrast to the observation reported by Campero and co-workers [13]. They reported that cobalt tetraphenyl porphyrins can undergo demetallation under acidic medium used for incorporation into SiO 2 gels and the effect induces changes in the UV/vis spectra.…”

“…For instance, this is particularly undesirable when the hybrid material is designed for photodynamic therapy. This promising application takes advantage of the fact that optimal tissue penetration by light lies in the range 650-800 nm-exactly the emission range of many porphyrins [13].…”

“…This problem has been overcome by the attachment of chemical substituents such as -OH and -NH 2 in the peripheral groups of the macrocycles [12]. In other cases, porphyrin aggregation, fluorescence suppression upon aging, and demetallation of metallated porphyrins under acidic conditions of the sol-gel procedure were described, making necessary the choice of a suitable solvent mixture to solve these problems [13]. Thus, the preparation of porphyrin containing sol-gel monoliths is not always free from complications, but in this work we present a porphyrin family that is particularly suitable for incorporation into sol-gel matrices.…”

Facile synthesis of silica monolith doped with meso-tetra(p-carboxyphenyl)porphyrin as a novel metal ion sensor

“…The TEOS precursor was hydrolyzed completely in the presence of ethanolic medium using HCl as the catalyst. DMF is used as the solvent for porphyrin and also as a protonation-inhibiting agent [15,16]. The DMF also served as drying control chemical additive which could reduce cracking to obtain stronger and larger monolithic material.…”

Homogeneous and Heterogeneous Free-Based Porphyrins Incorporated to Silica Gel as Fluorescent Materials and Visible Light Catalysts Mimic Monooxygenases

“…In the absence of DMF the main form of porphyrine is the cation. Sanchez et al (2004;2006;2009) reported about the free bases of the substituted tetraphenylporphyrins H 2 T(o-NH 2 )PP, H 2 T(p-COOH)PP and H 2 T(p-OH)PP, which were bound to the silica matrix by the use of the functionalized alkoxides 3-isocyanatopropyltriethoxysilane or 3-amminopropyltriethoxysilane, by the sol-gel method. It was shown, based on the UV-Vis spectra of all xerogels, that porphyrins are in stable forms inside the xerogel pores.…”