Synthesis and characterization of porphyrin-based porous coordination polymers obtained by supercritical CO2 extraction

Abstract

H2TCP and ZnTCP (TCP = 5,10,15,20-tetra(4-(phenoxy-4-yl)butanoic acid)porphyrin) were synthesized as gelator, reacted with Al(NO3)3·9H2O and Cr(NO3)3·9H2O by solvothermal and sol–gel method to give four organic–inorganic hybrid gels. The intermediate gels were extracted by supercritical CO2 to remove the redundant solvent molecules (DMF, EtOH) and the unreacted M3+ (M = Al, Cr), the final H2TCP-Al (PCP1), H2TCP-Cr (PCP2), ZnTCP-Al (PCP3), ZnTCP-Cr (PCP4) porous coordination polymers (PCPs) were obtained based on aerogels. The PCPs were characterized by FT-TR, UV–Vis, SEM, TEM and PXRD. Thermal stability and BET tests were carried by TGA and nitrogen sorption measurements. Results show that these PCPs exhibit superior thermal stability, tunable porosity and relative high BET surface ranging from 409 to 454 m2 g−1. Dyes adsorption experiments were performed to evaluate the adsorption capacity to dyes and the PCP3 has the best capacity which is 589 mg g−1 for rhodamine B (RhB) and 595 mg g−1 for methylene blue (MB). This work provides a promising method for the preparation of porous materials by supercritical CO2 extraction and exhibits some considerable applications in dyes adsorption.