Fabrication and properties of Sn(iv) porphyrin-linked porous organic polymer for environmental applications

Abstract

A robust porous organic polymer cross-linked by Sn(IV) porphyrin (SnPOP) was fabricated by reacting trans-dihydroxo-[5,15,10,20-tetrakis(phenyl)porphyrinato]tin(IV) (SnP) with fluorinated polyimide (FPI) via sol–gel formation, followed by supercritical CO₂ drying. The structural and porous properties of SnPOP were characterized using FT-IR, UV-vis, and fluorescence spectroscopies, along with field-emission scanning electron microscopy and gas sorption experiments. The reaction between the SnP's oxophilic Sn(IV) center and FPI's carboxylic acid moiety resulted in a controllable cross-linked porous texture. This material features the desirable physical properties of porphyrin and exhibits mesoporous structures with a relatively high surface area. SnPOP is thermally stable at temperatures up to 600 °C and highly resistant to boiling water, strong acids, and bases, owing to its assembly via formation of covalent bonds instead of typically weaker hydrogen bonds. The modified chemical and morphological structures of SnPOP showed an impressive CO₂ uptake capacity of 58.48 mg g⁻¹ at 273 K, with a preference for CO₂ over N₂. SnPOP showed significant efficiency in removing pollutant dyes, such as methylene blue and methyl orange, from dye-contaminated water. Additionally, SnPOP was a photocatalyst for fabricating silver nanoparticles of regular shape and size. All these properties make SnPOP a potential candidate for environmental applications like pollutant removal, gas storage, and separation.