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[Display omitted] • Metal phthalocyanine complexes are the catalysts for oxidation and other reactions. • μ-Nitrido diiron complexes feature a particular structure and catalytic properties. • Mild oxidation of methane. • Oxidative defluorination of heavily fluorinated aromatic compounds. • Flexibility of binuclear macrocyclic platform. For a long time biomimetic oxidation catalysis was mainly associated with metal porphyrin complexes. Phthalocyanine complexes, also belonging to large family of macrocyclic complexes have been under-investigated as catalysts until recently. In this review, we present the development of phthalocyanine catalytic chemistry at IRCELYON with a topical focus on contributions from our group during last 20 years and discuss recent research directions from personal perspective. Catalytic chemistry of phthalocyanine complexes is a rapidly growing field including not only oxidations but also many other reactions. Recent discovery of remarkable catalytic properties of μ-nitrido diiron phthalocyanines will give a new impetus and should even accelerate this development. These binuclear N-bridged complexes emerge as promising bio-inspired catalysts, in particular, for challenging reactions such as a low temperature oxidation of methane and oxidative defluorination of heavily fluorinated aromatic compounds. The scope of their catalytic applications is constantly increasing. The bimetallic construction is flexible and has a significant potential for further development including implementation of different ligands, metals and bridging groups. Consequently, the properties of this scaffold can be fine-tuned by platform architecture thus providing novel tools for catalysis. [ABSTRACT FROM AUTHOR]

The current coronavirus disease 2019 (COVID‐19) pandemic presents a global challenge for managing acutely ill patients and complications from viral infection. Systemic inflammation accompanied by a "cytokine storm," hemostasis alterations and severe vasculitis have all been reported to occur with COVID‐19, and emerging evidence suggests that dysregulation of lipid transport may contribute to some of these complications. Here, we aim to summarize the current understanding of the potential mechanisms related to COVID‐19 dyslipidemia and propose possible adjunctive type therapeutic approaches that modulate lipids and lipoproteins. Specifically, we hypothesize that changes in the quantity and composition of high‐density lipoprotein (HDL) that occurs with COVID‐19 can significantly decrease the anti‐inflammatory and anti‐oxidative functions of HDL and could contribute to pulmonary inflammation. Furthermore, we propose that lipoproteins with oxidized phospholipids and fatty acids could lead to virus‐associated organ damage via overactivation of innate immune scavenger receptors. Restoring lipoprotein function with ApoA‐I raising agents or blocking relevant scavenger receptors with neutralizing antibodies could, therefore, be of value in the treatment of COVID‐19. Finally, we discuss the role of omega‐3 fatty acids transported by lipoproteins in generating specialized proresolving mediators and how together with anti‐inflammatory drugs, they could decrease inflammation and thrombotic complications associated with COVID‐19. [ABSTRACT FROM AUTHOR]

Low temperature selective transformation of alkanes to useful products continues to be an important challenge in chemistry and industry. μ-Nitrido diiron phthalocyanines in combination with H 2 O 2 have been recently identified as powerful oxidation catalysts for these challenging reactions due to the formation of ultra-high valent diiron oxo species PcFe(IV)μNFe(IV) O(Pc + ). This very strong two-electron oxidizing species is generated from peroxo complex PcFe(IV)μNFe(III) O O R(Pc) (R H in the case of H 2 O 2 ) via heterolytic O O bond cleavage. Therein we show that the evolution of the peroxo diiron complex depends on the peroxide structure. Using t BuOOH we have demonstrated the formation of an one-electron oxidizing PcFe(IV)μNFe(IV) O(Pc) and t BuO radical via homolytic O O cleavage of the peroxocomplex. The reactivity of the μ-nitrido diiron tetra- t -butylphthalocyanine − t BuOOH catalytic system was investigated in the oxidation of different C H bonds in alkanes, olefins, aromatic and alkylaromatic compounds. The main products of cyclohexane oxidation were cyclohexanone and cyclohexanol whereas bicyclohexyl was formed in minor amounts even in the presence of O 2 and t BuOOH. Under optimal conditions, the turnover numbers of almost 5300 have been achieved. [ABSTRACT FROM AUTHOR]

Low temperature selective transformation of light alkanes of natural gas to useful products continues to be an important challenge in chemistry and industry. μ-Nitrido diiron phthalocyanines were recently identified as powerful oxidation catalysts capable of oxidizing methane, benzene and transforming poly- and perfluorinated aromatic compounds under oxidative conditions. Herein, we have supported two μ-nitrido diiron complexes onto silica, graphite or nafion and their catalytic performance has been evaluated in the heterogeneous oxidation of ethane in water. Acetic acid was obtained with selectivity up to 71%. Turnover number up to 58 and 50–65 % product yields can be achieved. The cleavage of C–C bond also occurred and formic acid was formed as side product. In contrast to methane oxidation, no strong influence of 75 mM acid was observed in ethane oxidation. The reactivities of C–H bonds in methane, ethane and propane were very similar when the reaction was performed in water. In contrast, in diluted acidic solution, the μ-nitrido diiron phthalocyanine – H 2 O 2 system exhibits 5 times higher activity in the oxidation of the methane C–H bond compared to the ethane C–H bond. [ABSTRACT FROM AUTHOR]

N-bridged dimers of tetrapyrroles complexed by transition metals have been known for nearly four decades, and gained renewed attention when their powerful oxidation properties were recently evidenced. This article is a state of the art review of the reported complexes and of their synthetic methods. Beyond classical chemistry characterization tools, speci?c methods appropriate to their structure are used and are presented in detail. Finally, their uses and importance of oxidation catalysts are reviewed. [ABSTRACT FROM AUTHOR]

Diiron macrocyclic complexes have been often considered as catalytically inert. However, numerous published examples of the catalytic oxidation reactions mediated by these complexes indicate their potential in catalysis. Mechanistic background for their applications as oxidation catalysts and their relationship with enzymatic and biomimetic oxidation involving cytochrome P-450 and soluble methane monooxygenase are discussed. A special emphasis was put on the N-bridged diiron phthalocyanine complexes as an emerging class of oxidation catalysts. Their unusual Fe(μN)Fe structure has interesting catalytic properties and reactivity. In addition to oxidation of strong C-H bonds in alkanes including methane, aromatic, and alkylaromatic compounds, μ-nitrido diiron phthalocyanines catalyze the oxidative dehalogenation and the formation of C-C bonds. A clean and practical character of the catalytic systems coupled with real availability of the phthalocyanines suggests a possibility of the application of this approach in industry. Great potential for further developments by modification of the catalysts structure can be envisioned. [ABSTRACT FROM AUTHOR]

The clean catalytic oxidation of 8-hydroxyquinoline (8-HQ) with tert-butyl hydroperoxide to quinoline-5,8-dione (QD), a molecular framework fragment of antitumor compounds, over silica-supported iron tetrasulfophthalocyanine catalysts (FePcS) is reported. The pronounced influence of the FePcS state (monomer vs.dimer) and the support (amorphous SiO2vs.mesoporous MCM-41) on the catalytic activity and selectivity is revealed. Depending on the catalyst structure, turnover frequency values determined from the initial rates of 8-HQ consumption varied from 215 to 3570 h−1.The effects of solvent, temperature, reagent concentrations and catalyst amounts on the substrate conversion and QD selectivity were studied to optimize the reaction conditions. With an optimal catalyst, the yield of the target product reached 66%. The truly heterogeneous nature of the catalysis was also demonstrated. [ABSTRACT FROM AUTHOR]

Abstract: The Baeyer-Villiger oxidation of cyclohexanone to caprolactone has been investigated at room temperature over AlFe-pillared clays, using oxygen as oxidant in the presence of benzaldehyde. A nearly complete conversion is observed with a selectivity into caprolactone above 80%. The observation of an induction period in the kinetics, of high activity of the non-pillared clay, and the detection of Fe traces in the reaction medium, suggest a process involving homogenous catalysis. The reaction is indeed catalysed in homogeneous phase by a few ppm of Fe. By contrast, iron phthalocyanine covalently supported on silica appears as a true heterogeneous catalyst, giving a selectivity above 95% to caprolactone at 61% conversion. [Copyright &y& Elsevier]

The oxidation of ethylenediaminetetraacetic acid (EDTA) and Na, Ca, Zn, Fe, and Mn EDTA complexes with hydrogen peroxide was studied in aqueous solution with the use of several metallophthalocyanines (MePcS) as catalysts. The impact of pH, temperature, and catalyst/substrate ratio were investigated. The most effective catalytic system under neutral conditions was FePcS-H2O2. In these laboratory-scale experiments, a catalyst/substrate/H2O2 molar ratio of 4:100:2000 was found to be optimal, while the effective reaction temperature was 40-60 °C. When the impact of metal speciation was studied, metal-specific degradation rates in the removal of these compounds were observed: all EDTA-metal complexes except Zn-EDTA were efficiently oxidized within three hours. The most degradable species was Fe(III)-EDTA. Among the catalysts, FePcS was found to be the most active in EDTA degradation. Over 90% of EDTA was removed in the presence of FePcS as catalyst within three hours of reaction time. [ABSTRACT FROM AUTHOR]

Abstract: The immobilisation of water-soluble metallophthalocyanine complexes on chitosan aerogel microspheres affords new bifunctional catalysts which have been used for the aerobic oxidation of β-isophorone. Chitosan is both the support of the metal complex and the organic base necessary for the reaction. These new materials have been characterized by nitrogen adsorption/desorption, scanning electron microscopy, diffuse reflectance UV–vis and 15N NMR spectroscopies. The influence of the reaction parameters on the efficiency of heterogeneous oxidation of β-isophorone, an important substrate for the preparation of flavour and fragrance fine chemicals has been studied. Combination of basic and oxidation sites in one solid material provided a more efficient heterogeneous clean oxidation of β-isophorone by O2 without any waste. [Copyright &y& Elsevier]

Two new catalytic processes have been developed to modify the hydrophilic/hydrophobic properties of insoluble, native starch. Soluble metal catalysts under proper reaction conditions were used to prepare tailor-made products suitable for various technological applications. Selective, clean oxidation of native starch by hydrogen peroxide in the presence of 0.003–0.016 mol% of iron tetrasulfonatophthalocyanine catalyst (FePcS) provided hydrophilic starch having 0.5–7 carboxyl and 1–11 carbonyl functions per 100 AGU (anhydroglucose units). The oxidation reaction was performed either with starch suspended in catalyst solution or by impregnation of starch powder with catalyst solution (dry process). Only small amounts of water, hydrogen peroxide and cheap FePcS catalysts were needed in the dry process to achieve a successful modification of starch in one step with almost quantitative yields. Hydrophobic starches with degree of substitution ranging from 0.08 to 0.43 per AGU have been prepared by butadiene telomerization in the presence of soluble palladium complexes. The best results in terms of degree of substitution at 50 °C have been obtained with Pd/TPPTS catalyst. The telomerization of starch with isoprene was also demonstrated. The etherified starch can be further transformed by hydrogenation using Wilkinson-type catalyst in EtOH/H2O. [ABSTRACT FROM AUTHOR]

High yields of epoxides were obtained in the oxidation of a large range of olefins using 1.2–2 equiv. of H2O2 in the presence of iron helmet phthalocyanines. The involvement of high-valent iron oxo species was evidenced using cryospray mass spectrometry. [ABSTRACT FROM AUTHOR]

Efficient alkane C–H bond oxidation was achieved using a newly designed Cu(ii)–hemicryptophane complex. Protection of the copper site in the inner cavity of the host leads to enhanced yields and allows discriminating cyclohexane from cyclooctane or adamantane in competitive experiments. [ABSTRACT FROM AUTHOR]

Metal phthalocyanine complexes encapsulated in MIL-101, and used as “ship-in-a-bottle” catalysts, show outstanding TONs in the aerobic oxidation of tetralin. [ABSTRACT FROM AUTHOR]

Abstract: Iron tetrasulfophthalocyanine (FePcS) supported catalyst was prepared by covalent grafting onto amino-modified silica by a novel practical one-pot method using activation of sulfonate groups of FePcS by triphenylphosphine triflate. FePcS–SiO2 in combination with tBuOOH behaved as an efficient catalyst for the oxidation of 2-methyl-1-naphthol to 2-methyl-1,4-naphthoquinone, vitamin K3. To optimise the catalytic system, the influence of different reaction parameters on the efficiency of this oxidation has been studied. Vitamin K3 was obtained with 59% selectivity at 96% conversion of 2-methyl-1-naphthol using only 0.5mol% of catalyst. 18O labelling experiments indicate a non-radical mechanism for this oxidation. [Copyright &y& Elsevier]

Abstract: Benzoic esters of 2-cyclohexen-1-ol and propargylic alcohols were prepared by direct selective copper-catalyzed allylic and propargylic oxidation of alkenes and alkynes, respectively, using t-butyl peroxybenzoate as the oxidant. The high olefin and acetylene conversions as well as the high product yields were obtained although enantioselectivity of this oxidation was moderate (e.e.<68%). The reported optimized catalytic procedure is clean since the oxidation is carried out under mild conditions using stoichiometric amounts of oxidant and catalytic amounts of (CuOTf)2C6H6 in combination with bisoxazoline ligands. [Copyright &y& Elsevier]

Abstract: New clean and efficient methods for the production of 2-methyl-1,4-naphthoquinone (MNQ, menadione, Vitamin K3) based on the oxidation of 2-methyl-1-naphthol (MNL) with cheap and environmentally benign oxidants, aqueous hydrogen peroxide, tert-butyl hydroperoxide and molecular oxygen, using three types of true heterogeneous catalysts, such as hydrothermally stable mesoporous titanium-silicate Ti-MMM-2, silica supported iron phthalocyanine and supported gold nanoparticles, are reported. Advantages and drawbacks of the catalytic systems are discussed. Surprisingly, non-catalytic oxidation of MNL with molecular oxygen shows superior selectivity and volume yield of MNQ compared to the known catalytic methods. [Copyright &y& Elsevier]

An advanced kinetic and diffusion model was developed and verified for the oxidation of starch by hydrogen peroxide in the presence of a homogeneous iron tetrasulphonatophtalocyanine (FePcS) catalyst. The model takes into account several experimentally confirmed observations, such as the oxidative formation of carbonyl and carboxyl groups in starch, as well as the decomposition of starch, catalyst and H 2 O 2 . The model is based on molecular mechanisms for the oxidation and decomposition reactions as well as on the dual structure of starch particles comprising an outer reaction layer and an internal porous layer, in which diffusion resistance retards the reaction rate. Adsorption of the catalyst on the starch surface is included in the model. The mathematical model explained very well the experimentally observed complex behavior of starch oxidation kinetics and hydrogen peroxide decomposition. [ABSTRACT FROM AUTHOR]

Review: 86 refs. [ABSTRACT FROM AUTHOR]

Efficient disposal of pollutants is a key problem in the environmental context. In particular, chlorinated aromatic compounds are recalcitrant to biodegradation and conventional treatment methods. Iron phthalocyanines were previously shown to be efficient catalysts for the oxidative degradation of chlorinated phenols considered as priority pollutants. We have recently discovered µ-nitrido diiron phthalocyanines as powerful oxidation catalysts. Herein, we evaluate these emerging catalysts in the oxidation of chlorinated phenols in comparison with conventional mononuclear complex. Catalytic performance of iron tetrasulfophthalocyanine (FePcS) and corresponding µ-nitrido dimer [(FePcS)2N] have been compared in the oxidation of chlorinated phenols by hydrogen peroxide in water. The oxidative degradation of 2,6-dichlorophenol (DCP) and 2,4,6-trichlorophenol (TCP) has been studied. The (FePcS)2N exhibited better catalytic properties than mononuclear FePcS in terms of conversion and mineralization (transformation of organic chlorine to Cl- and decrease of total organic carbon due to the formation of CO2). Kinetics of the DCP oxidation indicated that different reaction mechanisms are involved in the presence of FePcS and (FePcS)2N. The high catalytic activity of (FePcS)2N in the degradation and mineralization of chlorinated phenols make µ-nitrido diiron phthalocyanines promising catalyst to apply also in environmental remediation. [ABSTRACT FROM AUTHOR]

Abstract: μ-Nitrido diiron phthalocyanine [PcFe+3.5NFe+3.5Pc]0 is a highly efficient catalyst, able to oxidize methane under near-ambient conditions. In this work, high resolution X-ray emission spectroscopy (XES) and resonant inelastic X-ray scattering (RIXS) were applied to study iron species in the series of μ-nitrido diiron phthalocyanines including initial [PcFe+3.5NFe+3.5Pc]0 and oxidized complexes [PcFeIVNFeIVPc]+PF6 and [PcFeIVNFeIV(Pc +)]2+Br2 as model compounds for the intermediates in the catalytic cycle. These systems contain 3d4 configuration of iron in high oxidation state Fe(IV). XES spectra of Kβ line are sensible to the local iron spin density and show unexpected difference in the spin state between the initial [PcFe+3.5NFe+3.5Pc]0 (LS), one-electron oxidized [PcFeIVNFeIVPc]+PF6 (HS) and two electron oxidized cation radical species [PcFeIVNFeIV(Pc +)]2+Br2 (LS). Fe K-edge XANES spectra were recorded at the fluorescence energy of the main Kβ1,3 line or Kβ′ line in the Kβ emission spectrum. The conclusions of RIXS study corroborated XES data. Our study suggests that the main catalytic pathway of oxidation includes two-electron transformation from the LS initial complex to the LS two–electron oxidized [PcFeIVNFeIV(Pc +)(O)]0 to generate powerful oxidant able to oxidize methane via two-electron process. [Copyright &y& Elsevier]

Oxidation of 2-methyl-1-naphthol (MNL) with molecular oxygen proceeds efficiently under mild reaction conditions (3 atm O2, 60–80 °C) in the absence of any catalyst or sensitizer and produces 2-methyl-1,4-naphthoquinone (MNQ, menadione, or vitamin K3) with selectivity up to 80% in nonpolar solvents. 1H NMR and 1H,1H-COSY studies revealed the formation of 2-methyl-4-hydroperoxynaphthalene-1(4H)-one (HP) during the reaction course. Several mechanistic hypotheses, including conventional radical autoxidation, electron transfer mechanisms, photooxygenation, and thermal intersystem crossing (ISC), have been evaluated using spectroscopic, mass-spectrometric, spin-trapping, 18O2labeling, kinetic, and computational techniques. Several facts collectively implicate that ISC contributes significantly into MNL oxidation with O2at elevated pressure: (i) the reaction rate is unaffected by light; (ii) C–C-coupling dimers are practically absent; (iii) the reaction is first order in both MNL and O2; (iv) the observed activation parameters (ΔH‡= 8.1 kcal mol–1and ΔS‡= −50 eu) are similar to those found for the spin-forbidden oxidation of helianthrene with 3O2(Seip, M.; Brauer, H.-D. J. Am. Chem. Soc.1992, 114, 4486); and (v) the external heavy atom effect (2-fold increase of the reaction rate in iodobenzene) points to spin inversion in the rate-limiting step. [ABSTRACT FROM AUTHOR]

Abstract: The catalytic oxidation of 2-methyl-1-naphthol (MNL) to 2-methyl-1,4-naphthoquinone (MNQ; menadione; vitamin K3) using aqueous H2O2 as an oxidant and hydrothermally stable mesoporous mesophase titanium silicates Ti-MMM-2 as catalysts has been studied. The effects of mesopore diameter, temperature, solvent nature, reagent concentrations, and catalyst amount on the yield of MNQ were evaluated. Crucial factors affecting the MNQ yield include MNL concentration, H2O2/MNL molar ratio, reaction temperature, and the mode of MNL addition to the reaction mixture. Selectivity dramatically decreases with increasing MNL concentration and decreasing temperature. Stepwise addition of the substrate to the reaction mixture improves selectivity. Oxidation in the presence of 18O2 provided of unlabeled MNQ, indicating H2O2 as an oxygen source. The Ti-MMM-2 catalyst allows one to obtain MNQ with selectivity as high as 78% at complete substrate conversion. The catalyst can be used repeatedly without loss of either activity or selectivity. The proposed method is convenient and environmentally benign. [Copyright &y& Elsevier]