Biomimetic Homogeneous Oxidation Catalyzed by Metalloporphyrins with Green Oxidants

Cytochrome P-450 mono-oxygenase enzymes play a key role in the oxidative transformation in living systems. As one kind of cytochrome P-450 models, metalloporphyrins have been widely used in selective oxygenation of hydrocarbons under mild conditions. The chapter focuses on reviewing the biomimetic homogeneous oxidation of organic compounds catalyzed by metalloporphyrins with green oxidants such as dioxygen or hydrogen peroxide, in which the oxidized substrates include alkanes, olefins, alcohols, aldehydes, sulfides etc. The mechanisms for the oxidation of different substrates were also described. We can assume that the coming decade is going to be dedicated to the development of metalloporphyrins biomimetic catalyst in petrochemical and fine chemical industries. Keywords: Biomimetic, Cytochrome, Metalloporphyrins, Oxidation, Homogegeou

Solvent-free selective oxidation of primary and secondary alcohols catalyzed by ruthenium-bis(benzimidazole)pyridinedicarboxylate complex using hydrogen peroxide as an oxidant

AbstractA convenient and selective oxidation of alcohols with aqueous hydrogen peroxide to give the corresponding carbonyl compounds under solvent-free conditions has been developed. By applying ruthenium-bis(benzimidazole)pyridinedicarboxylate complex [Ru(bbp)(pydic)] as catalyst, primary, and secondary alcohols were oxidized to aldehydes and ketones in good yield and excellent selectivity under mild conditions

Diverse Applications of Nanomedicine

The design and use of materials in the nanoscale size range for addressing medical and health-related issues continues to receive increasing interest. Research in nanomedicine spans a multitude of areas, including drug delivery, vaccine development, antibacterial, diagnosis and imaging tools, wearable devices, implants, high-throughput screening platforms, etc. using biological, nonbiological, biomimetic, or hybrid materials. Many of these developments are starting to be translated into viable clinical products. Here, we provide an overview of recent developments in nanomedicine and highlight the current challenges and upcoming opportunities for the field and translation to the clinic. \ua9 2017 American Chemical Society

Hyperoxemia and excess oxygen use in early acute respiratory distress syndrome : Insights from the LUNG SAFE study

Publisher Copyright: © 2020 The Author(s). Copyright: Copyright 2020 Elsevier B.V., All rights reserved.Background: Concerns exist regarding the prevalence and impact of unnecessary oxygen use in patients with acute respiratory distress syndrome (ARDS). We examined this issue in patients with ARDS enrolled in the Large observational study to UNderstand the Global impact of Severe Acute respiratory FailurE (LUNG SAFE) study. Methods: In this secondary analysis of the LUNG SAFE study, we wished to determine the prevalence and the outcomes associated with hyperoxemia on day 1, sustained hyperoxemia, and excessive oxygen use in patients with early ARDS. Patients who fulfilled criteria of ARDS on day 1 and day 2 of acute hypoxemic respiratory failure were categorized based on the presence of hyperoxemia (PaO2 > 100 mmHg) on day 1, sustained (i.e., present on day 1 and day 2) hyperoxemia, or excessive oxygen use (FIO2 ≥ 0.60 during hyperoxemia). Results: Of 2005 patients that met the inclusion criteria, 131 (6.5%) were hypoxemic (PaO2 < 55 mmHg), 607 (30%) had hyperoxemia on day 1, and 250 (12%) had sustained hyperoxemia. Excess FIO2 use occurred in 400 (66%) out of 607 patients with hyperoxemia. Excess FIO2 use decreased from day 1 to day 2 of ARDS, with most hyperoxemic patients on day 2 receiving relatively low FIO2. Multivariate analyses found no independent relationship between day 1 hyperoxemia, sustained hyperoxemia, or excess FIO2 use and adverse clinical outcomes. Mortality was 42% in patients with excess FIO2 use, compared to 39% in a propensity-matched sample of normoxemic (PaO2 55-100 mmHg) patients (P = 0.47). Conclusions: Hyperoxemia and excess oxygen use are both prevalent in early ARDS but are most often non-sustained. No relationship was found between hyperoxemia or excessive oxygen use and patient outcome in this cohort. Trial registration: LUNG-SAFE is registered with ClinicalTrials.gov, NCT02010073publishersversionPeer reviewe

Substrate specificity in the biomimetic catalytic aerobic oxidation of styrene and cyclohexanone by metalloporphyrins: kinetics and mechanistic study

Substrate specificity is a hallmark of enzymatic catalysis. In this work, the biomimetic catalytic oxidation of styrene and cyclohexanone by iron (III) porphyrins and molecular oxygen was carried out, and remarkable differences in efficiency were observed. The specificity of the substrates for biomimetic catalytic oxidation was investigated by kinetics and mechanistic studies. Kinetics studies revealed that the oxidation of styrene followed Michaelis–Menten kinetics with KM ​= ​8.99 ​mol L-1, but the oxidation of cyclohexanone followed first-order kinetics with kobs ​= ​1.46 ​× ​10−4 ​s−1, indicating that the styrene epoxidation by metalloporphyrins exhibited characteristics of enzyme-like catalysis, while the oxidation of cyclohexanone was in agreement with the general rules of chemical catalysis. Different catalytic mechanisms for the two substrates were discussed by operando electron paramagnetic resonance spectroscopy, operando UV–vis spectroscopy, and KI/starch experiments. Substrate specificity was concluded to be attributed to the stability of high-valence species and oxygen transfer rate

Photocatalytic Degradation of Methyl Orange over Metalloporphyrins Supported on TiO2 Degussa P25

The photocatalytic activity of meso-tetraphenylporphyrins with different metal centers (Fe, Co, Mn and Cu) adsorbed on TiO2 (Degussa P25) surface has been investigated by carrying out the photodegradation of methyl orange (MO) under visible and ultraviolet light irradiation. The photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance UV (DRS-UV-vis) and infrared spectra. Copper porphyrin-sensitized TiO2 photocatalyst (CuP-TiO2) showed excellent activity for the photodegradation of MO whether under visible or ultraviolet light irradiation. Natural Bond Orbital (NBO) charges analysis showed that methyl orange ion is adsorbed easier by CuP-TiO2 catalyst due to the increase of induced interactions