Two-dimensional porous porphyrin materials composed of robust tin(IV)-porphyrin linkages for photocatalytic wastewater remediation.

Porphyrin-based two-dimensional porous materials (SnP-H2TCPP, SnP-ZnTCPP) composed of robust Sn(IV)-porphyrin linkages have been synthesized by reacting -dihydroxo[5,10,15,20-tetraphenylporphyrinato]tin(IV) (SnP) with [5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin] (HTCPP) and [5,10,15,20-tetrakis(4-carboxyphenyl)porphyrinato]zinc(II) (ZnTCPP), respectively. The strength of the interaction between the carboxylic acid group of the monomeric porphyrins (HTCPP and ZnTCPP) and the axial hydroxyl moiety of SnP enables the construction of highly stable framework materials, which were characterized by FT-IR, UV-vis, and emmission spectroscopy, powder XRD, elemental analysis, and thermogravimetric analysis (TGA). SnP-H2TCPP and SnP-ZnTCPP absorb visible light strongly over a wide range, demonstrating weak perturbation in the electronic ground state structures of the π-conjugated aromatic moieties compared to the starting monomeric units. TGA indicated that SnP-H2TCPP and SnP-ZnTCPP exhibited greater thermal stability than SnP. The permanent porosity of SnP-H2TCPP and SnP-ZnTCPP resulted in large specific surface areas (BET) of 210.0 m g and 185.0 m g, respectively. Uniform spherical nanoplates with an average diameter in the range of 900-1000 nm were observed for SnP-H2TCPP, whereas a nanocomposite morphology was observed for SnP-ZnTCPP, whose shape and size could not be specifically defined. Finally, the photodegradation performance of SnP-H2TCPP and SnP-ZnTCPP was found to be 89% ( = 0.0179 min) and 97% ( = 0.0246 min) within 120 min, respectively, for the degradation of methylene blue (MB), and 50% ( = 0.0091 min) and 60% ( = 0.0120 min) within 75 min, respectively, for the tetracycline (TC) antibiotic. The enhanced catalytic photodegradation activity of SnP-H2TCPP or SnP-ZnTCPP is attributed to the cooperation between the carboxylate-bearing porphyrin units and SnP.