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Astrobiology Aug 2019EXPOSE facilities were ESA multiuser facilities mounted outside the International Space Station for astrobiology experiments. Between 2008 and 2016, three series of...
EXPOSE facilities were ESA multiuser facilities mounted outside the International Space Station for astrobiology experiments. Between 2008 and 2016, three series of experiments were conducted involving chemical and biological samples to test their resistance and evolution in the space environment in low Earth orbit. In this special collection, results from two experiments of the EXPOSE-R2 campaign (2014-2016) are presented: Biofilm Organisms Surfing Space (BOSS) relating to biology and Photochemistry on the Space Station (PSS) dealing with astrochemistry.
Topics: Biofilms; Exobiology; Extraterrestrial Environment; Photochemistry; Spacecraft
PubMed: 31373529
DOI: 10.1089/ast.2019.0625 -
Chemical Reviews Jan 2022Photoinduced chemical transformations have received in recent years a tremendous amount of attention, providing a plethora of opportunities to synthetic organic... (Review)
Review
Photoinduced chemical transformations have received in recent years a tremendous amount of attention, providing a plethora of opportunities to synthetic organic chemists. However, performing a photochemical transformation can be quite a challenge because of various issues related to the delivery of photons. These challenges have barred the widespread adoption of photochemical steps in the chemical industry. However, in the past decade, several technological innovations have led to more reproducible, selective, and scalable photoinduced reactions. Herein, we provide a comprehensive overview of these exciting technological advances, including flow chemistry, high-throughput experimentation, reactor design and scale-up, and the combination of photo- and electro-chemistry.
Topics: Inventions; Photochemistry
PubMed: 34375082
DOI: 10.1021/acs.chemrev.1c00332 -
Angewandte Chemie (International Ed. in... Aug 2015A rapid and catalyst-free cycloaddition system for visible-light-induced click chemistry is reported. A readily accessible photoreactive 2H-azirine moiety was designed...
A rapid and catalyst-free cycloaddition system for visible-light-induced click chemistry is reported. A readily accessible photoreactive 2H-azirine moiety was designed to absorb light at wavelengths above 400 nm. Irradiation with low-energy light sources thus enables efficient small-molecule synthesis with a diverse range of multiple-bond-containing compounds. Moreover, in order to demonstrate the efficiency of the current approach, quantitative ligation of the photoactivatable chromophore with functional polymeric substrates was performed and full conversion with irradiation times of only 1 min at ambient conditions was achieved. The current report thus presents a highly efficient method for applications involving selective cycloaddition to electron-deficient multiple-bond-containing materials.
Topics: Catalysis; Click Chemistry; Light; Photochemistry; Polymers
PubMed: 26179164
DOI: 10.1002/anie.201504716 -
Nature Communications Jun 2022Photoremovable protecting groups (PPGs) represent one of the main contemporary implementations of photochemistry in diverse fields of research and practical...
Photoremovable protecting groups (PPGs) represent one of the main contemporary implementations of photochemistry in diverse fields of research and practical applications. For the past half century, organic and metal-complex PPGs were considered mutually exclusive classes, each of which provided unique sets of physical and chemical properties thanks to their distinctive structures. Here, we introduce the meso-methylporphyrin group as a prototype hybrid-class PPG that unites traditionally exclusive elements of organic and metal-complex PPGs within a single structure. We show that the porphyrin scaffold allows extensive modularity by functional separation of the metal-binding chromophore and up to four sites of leaving group release. The insertion of metal ions can be used to tune their spectroscopic, photochemical, and biological properties. We provide a detailed description of the photoreaction mechanism studied by steady-state and transient absorption spectroscopies and quantum-chemical calculations. Our approach applied herein could facilitate access to a hitherto untapped chemical space of potential PPG scaffolds.
Topics: Ions; Light; Metals; Photochemistry; Porphyrins
PubMed: 35750661
DOI: 10.1038/s41467-022-31288-2 -
Journal of Inorganic Biochemistry Aug 2020
Topics: Coordination Complexes; Humans; Luminescence; Macromolecular Substances; Nanoparticles; Photochemistry; Physics; Spectroscopy, Near-Infrared
PubMed: 32512347
DOI: 10.1016/j.jinorgbio.2020.111128 -
[Optically dissecting brain nicotinic receptor function with photo-controllable designer receptors].Biologie Aujourd'hui 2017Nicotinic acetylcholine receptors (nAChRs) are pentameric ligand-gated ion channels widely expressed in the central nervous system and the periphery. They play an... (Review)
Review
Nicotinic acetylcholine receptors (nAChRs) are pentameric ligand-gated ion channels widely expressed in the central nervous system and the periphery. They play an important modulatory role in learning, memory and attention, and have been implicated in various diseases such as Alzheimer's disease, Parkinson's disease, epilepsy, schizophrenia and addiction. These receptors are activated by the endogenous neurotransmitter acetylcholine, or by nicotine, the alkaloid found in tobacco leaves. Both molecules open the ion channel and cause the movement of cations across the membrane, which directly affects neuronal excitability and synaptic plasticity. nAChRs are very heterogeneous in their subunit composition (α2-10 et β2-4), in their brain distribution (cortex, midbrain, striatum…) and in their sub-cellular localization (pre- vs post-synaptic, axonal, dendritic…). This heterogeneity highly contributes to the very diverse roles these receptors have in health and disease. The ability to activate or block a specific nAChR subtype, at a defined time and space within the brain, would greatly help obtaining a clearer picture of these various functions. To this aim, we are developing novel optogenetic pharmacology strategies for optically controlling endogenous nAChR isoforms within the mouse brain. The idea is to tether a chemical photoswitch on the surface of a cysteine-modified nAChR, and use light for rapidly and reversibly turning that receptor mutant on and off. Here we will discuss the history of optogenetic pharmacology, and the recent advances for the optical control of brain nicotinic receptors in vivo.
Topics: Animals; Brain; Designer Drugs; Humans; Nicotinic Agonists; Nicotinic Antagonists; Optogenetics; Photochemical Processes; Photochemistry; Receptors, Nicotinic
PubMed: 29236669
DOI: 10.1051/jbio/2017022 -
Macromolecular Rapid Communications Jul 2017Brush block copolymers are a class of comb polymers that feature polymeric side chains densely grafted to a linear backbone. These polymers display interesting... (Review)
Review
Brush block copolymers are a class of comb polymers that feature polymeric side chains densely grafted to a linear backbone. These polymers display interesting properties due to their dense functionality, low entanglement, and ability to rapidly self-assemble to highly ordered nanostructures. The ability to prepare brush polymers with precise structures has been enabled by advancements in controlled polymerization techniques. This Feature Article highlights the development of brush block copolymers as photonic crystals that can reflect visible to near-infrared wavelengths of light. Fabrication of these materials relies on polymer self-assembly processes to achieve nanoscale ordering, which allows for the rapid preparation of photonic crystals from common organic chemical feedstocks. The characteristic physical properties of brush block copolymers are discussed, along with methods for their preparation. Strategies to induce self-assembly at ambient temperatures and the use of blending techniques to tune photonic properties are emphasized.
Topics: Light; Nanostructures; Photochemistry; Photons; Polymerization; Polymers
PubMed: 28544118
DOI: 10.1002/marc.201700058 -
Photochemical & Photobiological... May 2022Chemical actinometers are a useful tool in photochemistry, which allows to measure the photon flux of a light source to carry out quantitative analysis on...
Chemical actinometers are a useful tool in photochemistry, which allows to measure the photon flux of a light source to carry out quantitative analysis on photoreactions. The most commonly employed actinometers so far show minor drawbacks, such as difficult data treatment, parasite reactions, low stability or impossible reset. We propose herewith the use of 4,4'-dimethylazobenzene as a chemical actinometer. This compound undergoes a clean and efficient E/Z isomerization, approaching total conversion upon irradiation at 365 nm. Thanks to its properties, it can be used to determine the photon flux in the UV-visible region, with simple experimental methods and data treatment, and with the possibility to be reused after photochemical or thermal reset.
Topics: Photochemistry; Photons
PubMed: 35034332
DOI: 10.1007/s43630-021-00162-3 -
Organic Letters Jan 2024Photooxygenation of flavonoids leads to the release of carbon monoxide (CO). Our structure-photoreactivity study, employing several structurally different flavonoids,...
Photooxygenation of flavonoids leads to the release of carbon monoxide (CO). Our structure-photoreactivity study, employing several structurally different flavonoids, including their C-labeled analogs, revealed that CO can be produced via two completely orthogonal pathways, depending on their hydroxy group substitution pattern and the reaction conditions. While photooxygenation of the enol 3-OH group has previously been established as the CO liberation channel, we show that the catechol-type hydroxy groups of ring B can predominantly participate in photodecarbonylation.
Topics: Carbon Monoxide; Flavonoids; Photochemistry
PubMed: 38227978
DOI: 10.1021/acs.orglett.3c04141 -
The Journal of Organic Chemistry Dec 2022We develop the first method for catalytic, exhaustive alkoxylation of azobenzene photoswitches. Alkoxylation is known to improve the photoswitch properties that control...
We develop the first method for catalytic, exhaustive alkoxylation of azobenzene photoswitches. Alkoxylation is known to improve the photoswitch properties that control azobenzenes' success in chemical biology or materials sciences, e.g., better completeness of both → and → photoisomerizations and >100 nm red shift of photoresponse. Our method enables straightforward late-stage diversification of photoswitches with interesting functional handles. We showcase four applications: using it to rationally tune lipophilicity, prepare isotopic tracers for metabolism studies, install full water solubility without ionic charges, and efficiently access previously difficult mixed-substituent photoswitches. We also identified a previously unexplored mixed-substituent tetra- family, difluoro-dialkoxy-azobenzenes, whose photoresponse can outperform previous 'gold standard' tetrafluoro-, dichloro-difluoro-, and tetrachloro-azobenzenes in significant ways. We thus expect that both the scaffolds we showcase and the method we develop will impact broadly on photochemistry and photopharmacology.
Topics: Azo Compounds; Catalysis; Photochemistry
PubMed: 36475716
DOI: 10.1021/acs.joc.2c02214