scholarly journals Intramolecular, Visible Light-Mediated Aza Paternò-Büchi Reactions of Unactivated Alkenes

2021 ◽  
Author(s):  
Corinna Schindler ◽  
Dominique Blackmun ◽  
Stephen Chamness
Keyword(s):  
Visible Light ◽  
Oxidative Metabolism ◽  
Medicinal Chemistry ◽  
Complex Structures ◽  
Complex Architectures ◽  
Further Development

Azetidines are of particular interest in medicinal chemistry for their favorable properties, including increased resistance to oxidative metabolism and lower lipophilicity. The recent development of [2+2] reactions has significantly benefitted the previously limited methods for azetidine synthesis, but access to more complex architectures still requires further development. Herein we report a visible-light enabled intramolecular [2+2] cycloaddition to access tricyclic azetidines with 3D complex structures and high levels of saturation.

scholarly journals Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

2018 ◽  
Vol 14 ◽  
pp. 2035-2064 ◽  
Author(s):  
Michael K Bogdos ◽  
Emmanuel Pinard ◽  
John A Murphy
Keyword(s):  
Pharmaceutical Industry ◽  
Transition Metals ◽  
Visible Light ◽  
Reaction Mechanisms ◽  
General Class ◽  
Medicinal Chemistry ◽  
Organic Dyes ◽  
General Reaction ◽  
High Degree ◽  
Synthetic Medicinal

The focus of this review is to provide an overview of the field of organocatalysed photoredox chemistry relevant to synthetic medicinal chemistry. Photoredox transformations have been shown to enable key transformations that are important to the pharmaceutical industry. This type of chemistry has also demonstrated a high degree of sustainability, especially when organic dyes can be employed in place of often toxic and environmentally damaging transition metals. The sections are arranged according to the general class of the presented reactions and the value of these methods to medicinal chemistry is considered. An overview of the general characteristics of the photocatalysts as well as some electrochemical data is presented. In addition, the general reaction mechanisms for organocatalysed photoredox transformations are discussed and some individual mechanistic considerations are highlighted in the text when appropriate.

scholarly journals Numerical implementation of multiple peeling theory and its application to spider web anchorages

2015 ◽  
Vol 5 (1) ◽  
pp. 20140051 ◽  
Author(s):  
Lucas Brely ◽  
Federico Bosia ◽  
Nicola M. Pugno
Keyword(s):  
Numerical Model ◽  
Numerical Approach ◽  
Complex Structures ◽  
Numerical Implementation ◽  
Spider Web ◽  
Complex Architectures ◽  
Fibrillar Adhesives

Adhesion of spider web anchorages has been studied in recent years, including the specific functionalities achieved through different architectures. To better understand the delamination mechanisms of these and other biological or artificial fibrillar adhesives, and how their adhesion can be optimized, we develop a novel numerical model to simulate the multiple peeling of structures with arbitrary branching and adhesion angles, including complex architectures. The numerical model is based on a recently developed multiple peeling theory, which extends the energy-based single peeling theory of Kendall, and can be applied to arbitrarily complex structures. In particular, we numerically show that a multiple peeling problem can be treated as the superposition of single peeling configurations even for complex structures. Finally, we apply the developed numerical approach to study spider web anchorages, showing how their function is achieved through optimal geometrical configurations.

scholarly journals Control of Membrane Fouling in Organics Filtration Using Ce-Doped Zirconia and Visible Light

Nanomaterials ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 534 ◽  
Author(s):  
Fabrício Bortot Coelho ◽  
Chiara Gionco ◽  
Maria Paganini ◽  
Paola Calza ◽  
Giuliana Magnacca
Keyword(s):  
Visible Light ◽  
Surface Waters ◽  
Membrane Fouling ◽  
Sol Gel ◽  
Fouling Resistance ◽  
Environmental Implications ◽  
Light Emitting ◽  
Treatment Processes ◽  
Further Development ◽  
Zirconia Nanoparticles

Membrane fouling has been a major issue in the development of more efficient water treatment processes. Specifically in surface waters filtration, organic matter, such as humic-like substances, can cause irreversible fouling. Therefore, this study evaluates the activity of a photocatalytic layer composed of Ce-doped zirconia nanoparticles in improving the fouling resistance during filtration of an aqueous solution of humic acid (HA). These nanoparticles were prepared by hydrothermal and sol–gel processes and then characterized. Before the filtration experiments, the photodegradation of HA catalyzed by Ce-doped zirconia nanoparticles in dispersion was studied. It was observed that the sol–gel prepared Ce-ZrO2 exhibited higher HA removal in practically neutral pH, achieving 93% efficiency in 180 min of adsorption in the dark followed by 180 min under visible-light irradiation using light-emitting diodes (LEDs). Changes in spectral properties and in total organic carbon confirmed HA degradation and contributed to the proposal of a mechanism for HA photodegradation. Finally, in HA filtration tests, Ce-ZrO2 photocatalytic membranes were able to recover the flux in a fouled membrane using visible-light by degrading HA. The present findings point to the further development of anti-fouling membranes, in which solar light can be used to degrade fouling compounds and possibly contaminants of emerging concern, which will have important environmental implications.

A review on advanced imaging technologies for the quantification of wicking in textiles

2016 ◽  
Vol 87 (1) ◽  
pp. 110-132 ◽  
Author(s):  
M Parada ◽  
D Derome ◽  
RM Rossi ◽  
J Carmeliet
Keyword(s):  
Visible Light ◽  
Historical Perspective ◽  
Imaging Techniques ◽  
Spot Test ◽  
Advanced Imaging ◽  
X Ray ◽  
Imaging Technologies ◽  
Strip Test ◽  
Further Development

This review covers imaging techniques of wicking in textiles ranging from visible light to synchrotron x-ray. First, the wicking phenomenon and its relevance are exposed. Then, the main wicking experimental setups, namely the strip test and the spot test, are described. Next, the imaging techniques are described together with the relevant studies applied to wicking. Finally, the analysis of wicking measurements is presented. The conclusion presents imaging techniques applied to wicking in a historical perspective and highlights areas where further development is desirable.

scholarly journals Tyrosine and Drug-like Late-stage Benzylic Functionalization via Photoredox Catalysis

2020 ◽  
Author(s):  
Tobias Brandhofer ◽  
Volker Derdau ◽  
María Mendez ◽  
Christoph Pöverlein ◽  
Olga Garcia Mancheno
Keyword(s):  
Natural Products ◽  
Visible Light ◽  
Late Stage ◽  
Medicinal Chemistry ◽  
Functional Group ◽  
Reaction Conditions ◽  
Site Selectivity ◽  
Wide Range ◽  
High Yields ◽  
Therapeutic Compounds

Abstract Visible light mediated late-stage functionalization is a rising field in synthetic and medicinal chemistry, allowing the fast and diversified modification of valuable, potentially therapeutic compounds such as peptides. However, there are relatively few mild methodologies for the C(sp3)-H functionalization of complex peptides. Herein, we report a visible light mediated photocatalytic protocol for the benzylic C-H modification of tyrosine and related C-H bonds. The embraced radical-cation/deprotonation strategy enables an incorporation of a wide range of valuable functional groups in high yields and chemoselectivity. The mild reaction conditions, site-selectivity and high functional group tolerance was highlighted by the functionalization of complex peptides, drugs and natural products, providing a promising synthetic platform in medicinal chemistry.

scholarly journals Solar-Driven Photoelectrochemical Performance of Novel ZnO/Ag2WO4/AgBr Nanorods-Based Photoelectrodes

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Elfatih Mustafa ◽  
Rania E. Adam ◽  
Polla Rouf ◽  
Magnus Willander ◽  
Omer Nur
Keyword(s):  
Visible Light ◽  
Water Oxidation ◽  
Photoelectrochemical Performance ◽  
Silar Method ◽  
Light Water ◽  
Layer Adsorption ◽  
Basic Understanding ◽  
Growth Method ◽  
Further Development ◽  
Ionic Layer

Abstract Highly efficient photoelectrochemical (PEC) water oxidation under solar visible light is crucial for water splitting to produce hydrogen as a source of sustainable energy. Particularly, silver-based nanomaterials are important for PEC performance due to their surface plasmon resonance which can enhance the photoelectrochemical efficiency. However, the PEC of ZnO/Ag2WO4/AgBr with enhanced visible-light water oxidation has not been studied so far. Herein, we present a novel photoelectrodes based on ZnO/Ag2WO4/AgBr nanorods (NRs) for PEC application, which is prepared by the low-temperature chemical growth method and then by successive ionic layer adsorption and reaction (SILAR) method. The synthesized photoelectrodes were investigated by several characterization techniques, emphasizing a successful synthesis of the ZnO/Ag2WO4/AgBr heterostructure NRs with excellent photocatalysis performance compared to pure ZnO NRs photoelectrode. The significantly enhanced PEC was due to improved photogeneration and transportation of electrons in the heterojunction due to the synergistic effect of the heterostructure. This study is significant for basic understanding of the photocatalytic mechanism of the heterojunction which can prompt further development of novel efficient photoelectrochemical-catalytic materials. Graphic Abstract

Functionalized Azetidines Via Visible Light-Enabled Aza Paternò-Büchi Reactions

2019 ◽  
Author(s):  
Marc R. Becker ◽  
Alistair D. Richardson ◽  
Corinna S. Schindler
Keyword(s):  
General Solution ◽  
Visible Light ◽  
Medicinal Chemistry ◽  
Cycloaddition Reaction ◽  
Direct Approach ◽  
Synthetic Methods ◽  
Great Promise ◽  
Reaction Paths ◽  
Synthetic Utility ◽  
Direct Formation

<p>Azetidines are four-membered nitrogen-containing heterocycles that hold great promise in current medicinal chemistry due to their desirable pharmacokinetic effects. However, a lack of efficient synthetic methods to access functionalized azetidines has hampered their incorporation into pharmaceutical lead structures. As [2+2] cycloaddition reaction between imines and alkenes, the aza Paternò-Büchi reaction arguably represents the most direct approach to functionalized azetidines. Currently, competing reaction paths accessible upon photochemical excitation of the substrates greatly restrict the synthetic utility of these transformations. We herein report the development of a visible light-enabled aza Paternò-Büchi reaction that surmounts existing limitations and represents a general solution for the direct formation of functionalized azetidines from imine and alkene containing precursors.<br></p><br><p></p>

Phototherapy and extracorporeal membrane oxygenation facilitate removal of carbon monoxide in rats

2019 ◽  
Vol 11 (513) ◽  
pp. eaau4217
Author(s):  
Luca Zazzeron ◽  
Anna Fischbach ◽  
Walfre Franco ◽  
William A. Farinelli ◽  
Fumito Ichinose ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Acute Lung Injury ◽  
Lung Injury ◽  
Visible Light ◽  
Smoke Inhalation ◽  
Co Poisoning ◽  
Membrane Oxygenator ◽  
Injury Treatment ◽  
Further Development

Inhaled carbon monoxide (CO) displaces oxygen from hemoglobin, reducing the capacity of blood to carry oxygen. Current treatments for CO-poisoned patients involve administration of 100% oxygen; however, when CO poisoning is associated with acute lung injury secondary to smoke inhalation, burns, or trauma, breathing 100% oxygen may be ineffective. Visible light dissociates CO from hemoglobin. We hypothesized that the exposure of blood to visible light while passing through a membrane oxygenator would increase the rate of CO elimination in vivo. We developed a membrane oxygenator with optimal characteristics to facilitate exposure of blood to visible light and tested the device in a rat model of CO poisoning, with or without concomitant lung injury. Compared to ventilation with 100% oxygen, the addition of extracorporeal removal of CO with phototherapy (ECCOR-P) doubled the rate of CO elimination in CO-poisoned rats with normal lungs. In CO-poisoned rats with acute lung injury, treatment with ECCOR-P increased the rate of CO removal by threefold compared to ventilation with 100% oxygen alone and was associated with improved survival. Further development and adaptation of this extracorporeal CO photo-removal device for clinical use may provide additional benefits for CO-poisoned patients, especially for those with concurrent acute lung injury.

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