A porphyrin-based metallacage for enhanced photodynamic therapy

In this study, we designed an effective nanoplatform to improve the photodynamic therapy (PDT) of porphyrins. Combining a porphyrin-based metallacage (PM), hyaluronidase (HAase) and DSPE-mPEG2000 together, the nanoparticle (PM@HAase-mPEG) showed enhanced PDT efficacy. The PM improved the stability of the porphyrin, avoided its aggregation and provided cavities to concentrate oxygen molecules, which was beneficial for enhancing PDT. HAase degraded HA to increase the intracellular accumulation of nanoparticles, normalized blood vessels and relieved hypoxia in tumors. PM@HAase-mPEG inhibited the growth of tumors in a 4T1 mouse model by the generated singlet oxygen with excellent PDT efficacy. This study resolved the problems of the instability of PSs, less cellular accumulation of drugs, and tumor hypoxia that limited the anti-tumor application of PDT.

One-pot, facile synthesis and fast separation of a UiO-66 composite by a metalloporphyrin using nanomagnetic materials for oxidation of olefins and allylic alcohols

One-pot facile synthesis of a new composite based on the incorporation of a metalloporphyrin within the UiO-66 metal–organic framework is reported.

Heterogenisation of polyoxometalates and other metal-based complexes in metal–organic frameworks: from synthesis to characterisation and applications in catalysis

This review provides a thorough overview of composites with molecular catalysts (polyoxometalates, or organometallic or coordination complexes) immobilised into MOFs via non-covalent interactions.

Effect of porphyrin metal center on synthesis, structure, morphology and oxygen reduction properties of porphyrin encapsulated metal organic frameworks

A series of different metal centered 5,15-Bis(4-aminophenyl)-10,20-bis(4-bromophenyl)porphyrins (PorM) where M = H2, MnOAc, FeCl, Co or Zn were synthesized, and then encapsulated in zeolite imidazole framework-8 (ZIF-8) by typical template directed strategy to generate PorM@ZIF-8 metal organic frameworks (MOFs). These composites were characterized by UV-vis, FTIR, XRD, FESEM and HRTEM methods. Each prepared PorM@ZIF-8 MOF retained the molecular structure of porphyrin and crystal structure of ZIF-8. It is clearly shown that porphyrin centered metal ions will affect MOFs morphology. Both PorH2@ZIF-8 and PorZn@ZIF-8 gave a rhombic dodecahedron, PorMnOAc@ZIF-8 gave a truncated hexagonal prism-like structure, while no specific structures were obtained for PorFeCl@ZIF-8 and PorCo@ZIF-8 due to aggregation as characterized by FESEM spectrum. Oxygen reduction catalytic ability of ZIF-8, PorM and PorM@ZIF-8 were measured in alkaline condition (0.1 M KOH) with the number of electrons transferred being [Formula: see text] = 2.20–2.60 and generating HO[Formula: see text] as the oxygen reduction product. The catalytic property slightly increased after the porphyrin was encapsulated, due possibly to the capacity limit, inappropriate molecular distance or the direction of encapsulated porphyrin molecular.

Metal-Organic Framework Nanoparticles Induce Pyroptosis in Cells Controlled by the Extracellular pH

Ion homeostasis is essential for cellular survival, and elevated concentrations of specific ions are used to start distinct forms of programmed cell death. However, investigating the influence of certain ions on cells in a controlled way has been hampered due to the tight regulation of ion import by cells. Here, it is shown that lipid-coated iron-based metal-organic framework nanoparticles are able to deliver and release high amounts of iron ions into cells. While high concentrations of iron often trigger ferroptosis, here, the released iron induces pyroptosis, a form of cell death involving the immune system. The iron release occurs only in slightly acidic extracellular environments restricting cell death to cells in acidic microenvironments and allowing for external control. The release mechanism is based on endocytosis facilitated by the lipid-coating followed by degradation of the nanoparticle in the lysosome via cysteine-mediated reduction, which is enhanced in slightly acidic extracellular environment. Thus, a new functionality of hybrid nanoparticles is demonstrated, which uses their nanoarchitecture to facilitate controlled ion delivery into cells. Based on the selectivity for acidic microenvironments, the described nanoparticles may also be used for immunotherapy: the nanoparticles may directly affect the primary tumor and the induced pyroptosis activates the immune system.

Highly Active Catalysis of Cobalt Tetrakis(pentafluorophenyl)porphyrin Promoted by Chitosan for Cyclohexane Oxidation in Response-Surface-Methodology-Optimized Reaction Conditions

We aimed at elevating catalytic performances of cobalt tetrakis(pentafluorophenyl)porphyrin (Co TPFPP) through axial coordination, nanocavities, and covalently grafting action. The Co TPFPP was immobilized onto nanoporous and nonporous chitosan, forming Co TPFPP/np‐ and nonp‐CTS catalysts, respectively. The catalysts were characterized by various spectroscopic techniques. The catalytic performances of these catalysts for cyclohexane oxidation under response‐surface‐methodology‐optimized oxidation reaction conditions were estimated and compared. Co TPFPP/np‐CTS was an excellent catalyst at aspect of catalytic activity, exhibiting the considerable potential reusability, 24.2 mol % yields (KA oil : cyclohexanone and cyclohexanol) in average, and total turnover frequencies (TOFs) of 3.25×10⁶ h⁻¹. This is attributed to the structural characteristics of the Co TPFPP/np‐CTS catalyst: the cobalt porphyrin molecules could be highly scattered on CTS, forming the independent active sites, and were not leached. The axial coordination exerted the most important effect on the catalytic activity, and the covalent grafting action had a decisive effect on the increase of the total TOFs and on the reusability of the catalyst.

A Cu-Doped ZIF-8 metal organic framework as a heterogeneous solid catalyst for aerobic oxidation of benzylic hydrocarbons

Cu(ii) ions doped into ZIF-8 MOFs are shown to activate C–H bonds in benzylic hydrocarbons to their corresponding alcohol/ketone products.

Heterogenization of manganese porphyrin via hydrogen bond in zeolite imidazolate framework-8 matrix, a host–guest interaction, as catalytic system for olefin epoxidation

A heterogenized meso-tetrakis(2,3-dihydroxyphenyl)porphyrinatomanganese(III) acetate at zeolite imidazolate framework-8 (T(2,3-OHP)PorMn@ZIF-8) is investigated for the catalytic olefin epoxidation reactions at room temperature. Heterogenization is accomplished through a non-classical hydrogen bond proposed between T(2,3-OHP)PorMn bearing O–H groups and C–H of the 2-methylimidazolate linkers in the ZIF-8 structure. The aforementioned compound is characterized by X-ray powder diffraction (XRD), atomic absorption spectroscopy (AAS), nitrogen adsorption−desorption, FT-IR spectroscopy, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The catalytic system with rather high potential of reusability is proposed as a fairly efficient epoxidation catalyst compared to reports in homogeneous media.

Rational Design of Catalytic Centers in Crystalline Frameworks

Crystalline frameworks including primarily metal organic frameworks (MOF) and covalent organic frameworks (COF) have received much attention in the field of heterogeneous catalysts recently. Beyond providing large surface area and spatial confinement, these crystalline frameworks can be designed to either directly act as or influence the catalytic sites at molecular level. This approach offers a unique advantage to gain deeper insights of structure-activity correlations in solid materials, leading to new guiding principles for rational design of advanced solid catalysts for potential important applications related to energy and fine chemical synthesis. In this review, recent key progress achieved in designing MOF- and COF-based molecular solid catalysts and the mechanistic understanding of the catalytic centers and associated reaction pathways are summarized. The state-of-the-art rational design of MOF- and COF-based solid catalysts in this review is grouped into seven different areas: (i) metalated linkers, (ii) metalated moieties anchored on linkers, (iii) organic moieties anchored on linkers, (iv) encapsulated single sites in pores, and (v) metal-mode-based active sites in MOFs. Along with this, some attention is paid to theoretical studies about the reaction mechanisms. Finally, technical challenges and possible solutions in applying these catalysts for practical applications are also presented.

A recyclable hybrid manganese(III) porphyrin magnetic catalyst for selective olefin epoxidation using molecular oxygen

The synthesis and characterization of a hybrid Mn(III)-porphyrin magnetic nanocomposite is described. Moreover, a sustainable methodology for epoxidation of olefins is reported, using O[Formula: see text] as a green oxidant and the magnetic nanoparticle as a recyclable catalyst. High activity in alkene oxidation was observed, with full selectivity for epoxide formation. The magnetic catalyst presented high stability, being recovered and reused in five consecutive runs without loss of catalytic activity or selectivity in cyclooctene oxidation. Moreover, the catalytic system showed very good reactivity toward epoxidation of a range of terminal, substituted, cyclic or acyclic, aliphatic and aromatic olefins, including terpene and steroid derivatives, affording a range of biologically relevant epoxides in excellent yields. The isobutyric acid, formed as side-product, was recovered with high yield and purity, which provides the potential reutilization of this important industrial product.

Stable metal–organic frameworks as a host platform for catalysis and biomimetics

Recent years have witnessed the exploration and synthesis of an increasing number of metal–organic frameworks (MOFs). The utilization of stable MOFs as a platform for catalysis and biomimetics is discussed.

A metalloporphyrin-based porous organic polymer as an efficient catalyst for the catalytic oxidation of olefins and arylalkanes

A metalloporphyrin-based porous organic polymer contains both micropores and mesopores, which are favourable for mass transfer in heterogeneous catalysis.