Supercritical CO₂ Synthesis of Porous Metalloporphyrin Frameworks: Application in Photodynamic Therapy

Abstract

A series of porous metalloporphyrin frameworks prepared from the 5,10,15,20-tetra(4-pyridyl)porphyrin (H 2 TPyP) linker and four metal complexes, M(hfac) 2 M = Cu(II), Zn(II), Co(II), and Ni(II) (hfac: 1,1,1,5,5,5-hexafluoroacetylacetonate), were obtained using supercritical CO 2 (scCO 2 ) as a solvent. All the materials, named generically as [M-TPyP] n , formed porous metal− organic frameworks (MOFs), with surface areas of ∼450 m 2 g −1 . All MOFs were formed through the coordination of the metal to the exocyclic pyridine moieties in the porphyrin linker. For Cu(II), Zn(II), and Co(II), incomplete metal coordination of the inner pyrrole ring throughout the structure was observed, giving place to MOFs with substitutional defects and leading to a certain level of disorder and limited crystallinity. These samples, prepared using scCO 2 , were precipitated as nano-to micrometric powders. Separately, a layering technique from a mixture of organic solvents was used to crystallize high-quality crystals of the Co(II) based MOF, obtained with the formula [{Co(hfac) 2 } 2 H 2 TPyP] n . The crystal structure of this MOF was elucidated by single-crystal synchrotron X-ray diffraction. The Zn(II)-based MOF was selected as a potential photodynamic therapy drug in the SKBR-3 tumoral cell line showing outstanding performance. This MOF resulted to be nontoxic, but after 15 min of irradiation at 630 nm, using either 1 or 5 μM concentration of the product, almost 70% of tumor cells died after 72 h.

Porphyrin-Based Metal-Organic Framework Materials: Design, Construction, and Application in the Field of Photocatalysis

“…The porphyrin linkers in porphyrin-based MOFs mainly include carboxylic acids, pyridines, and polyazole groups [ 72 , 73 , 74 ]. The following are most of the porphyrin ligands that are commonly used in porphyrin-based MOFs, shown in Figure 2 [ 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 ].…”

Coupling atomic layer deposition with supercritical fluid processing to provide a highly C3H6‐selective ZIF‐8 membrane

“…Supercritical fluids (SCFs), which represent substances above their critical temperatures and pressures where definite liquid and gas phases disappear, exhibit enormous promise for sustainable production of highquality MOF membranes due to their unusual physicochemical properties such as mild critical condition, chemical inertness, controllable diffusivity, and variable solubility. [39][40][41][42][43][44][45][46][47] Very recently, ZIF-8 membranes showing decent C 3 H 6 /C 3 H 8 permselectivity were prepared by our group through SCF processing of sol-gel-derived (SGD) ZnO buffer layers in supercritical CO 2 (scCO 2 ) environments. 45 Compared with other methods, in this method, residual 2-methylimidazole (2-mIm) ligands together with vented gaseous CO 2 could be efficiently recovered, which aided in the achievement of zero pollutant discharge.…”