Visible Light Photocatalysts Based on Homogeneous and Heterogenized Tin Porphyrins

Abstract

Visible light photocatalysis using water-soluble tin porphyrin (s-SnP, [Sn(OH 2 ) 2 (TPy H P)](NO 3 ) 6 ) and waterinsoluble tin porphyrin Sn(OH) 2 (TPP) (ins-SnP) immobilized on SiO 2 (hetero-SnP) was investigated. The visible light photocatalytic activities of s-SnP and hetero-SnP were demonstrated successfully for the degradation of 4-chlorophenol (4-CP) and acid orange 7 (AO7) in water. The visible light activity of hetero-SnP increased with the ins-SnP loading and was saturated above 77 mg/g-SiO 2 , which corresponded to the homogeneous concentration of [ins-SnP] ) 50 µM. It is the Q band of SnP (500-650 nm) that is photocatalytically active under visible light, not the Soret band (420-430 nm) whose absorption intensity is much higher. When applied to the degradation of 4-CP and AO7, hetero-SnP was particularly stable and could be used repeatedly without losing the activity whereas the activity of s-SnP was reduced gradually with repeated uses. The photocatalytic degradation reactions of 4-CP, AO7, and other organic substrates were studied systematically to show that the operating mechanisms are very different depending on the kind of substrates. The properties and activities of s-SnP and hetero-SnP as visible light photocatalysts were investigated in various ways and discussed in detail.

Tin porphyrin immobilization significantly enhances visible-light-photosensitized degradation of Microcystins: Mechanistic implications

“…Crude hexakis adduct was isolated using a liquid chromatography, hydrolyzed and subsequently converted into its hydrochloride salt, and then purified by dialysis and dried in vacuum. trans-dihydroxo [5,10,15,20-tetraphenylporphyrinato]tin(IV), Sn(OH) 2 (TPP) and trans-dihydroxo [5,10,15,20-tetrakis-(4-pyridyl) porphyrinato]tin(IV), Sn(OH) 2 (TPyP) were prepared using the previously-reported method [31]. The former one (i.e., ins-SnP), which exhibits extremely low aqueous solubility, was immobilized on silica support to form tin porphyrin-based heterogeneous sensitizer, SnP/silica.…”

“…High-valent Sn(IV) incorporated into the porphyrin center enables electron transfer from organic substrates to 3 SnP * [31], providing an alternative reaction route for photocatalytic oxidative degradation. Our previous study [26] showed that visible light irradiation of SnP/silica led to rapid degradation of neutral phenolic compounds that are not susceptible to singlet oxygenation by aminoC 60 /silica.…”

Photochemical Transformations Involving Porphyrins and Phthalocyanines

“…Visible light photocatalysis using SiO 2 immobilized water-soluble and -insoluble tin porphyrins degraded 4-chlorophenol and Acid Orange 7 in water. Interestingly, the visible light activity of the porphyrin photocatalyst was enhanced by increasing the loading of insoluble tin porphyrin (Kim et al 2008). Photocatalysts prepared in situ by CuPc immobilization on Al and encapsulated inside zeolite-X showed a remarkable affinity towards CN − .…”

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

“…A similar carrier covalently modified with the metal-free monopyridyltriphenylporphyrin, introduced into a polymer microchannel and the microchip were applied for photodecomposition of phenol under solution-flow conditions (Kitamura et al, 2006). Very recently a visible light photocatalytical system based on waterinsoluble tin porphyrin Sn(OH) 2 (TPP) immobilized on SiO 2 has been successfully used for the degradation of 4-chlorophenol and acid orange 7 (Kim et al, 2008). Silica microspheres functionalized with 5-(4-allyloxy)phenyl-10,15,20-tri(2,6-dichlorophenyl)porphyrin have been prepared by Huang et al for the photooxidation of 1,5-dihydroxynaphthalene under visible light irradiation in the aerated aqueous solution (Cai et al, 2009).…”