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Search for "photochemistry" in Full Text gives 158 result(s) in Beilstein Journal of Organic Chemistry.

Heterogeneous photocatalysis in flow chemical reactors

  • Christopher G. Thomson,
  • Ai-Lan Lee and
  • Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

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  • has shifted the paradigms of photochemistry, opening new avenues of research with safer and scalable processes that can be readily implemented in academia and industry. Current state-of-the-art photocatalysts are homogeneous transition metal complexes that have favourable photophysical properties
  • photon and mass transport. Photocatalysis provides a unique route to carry out complex chemical transformations under mild conditions that are often impossible with “standard” organic synthetic procedures. The earliest report of synthetic photochemistry can be traced back to Trommsdorf in 1834, who
  • observed that crystals of santonine would shatter when exposed to sunlight [28]. Credit for the pioneering of photochemistry is usually given to Ciamician, the “grandfather of photochemistry”, who reported many interesting transformations of chemical solutions when irradiated by sunlight [29][30]. His
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Published 26 Jun 2020

An overview on disulfide-catalyzed and -cocatalyzed photoreactions

  • Yeersen Patehebieke

Beilstein J. Org. Chem. 2020, 16, 1418–1435, doi:10.3762/bjoc.16.118

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  • variety of reactions, renders them a class of green, economic, mild, and chemoselective radical catalyst. Apart from this, they are also excellent HAT catalysts in photoredox catalysis systems [2][3]. In various types of organic photochemistry reactions, such as cyclizations, anti-Markovnikov additions
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Published 23 Jun 2020

Recent synthesis of thietanes

  • Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

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  • derivatives 287–291 [78] (Scheme 52). In 1988, Kanaoka et al. studied the photochemistry of semicyclic and acyclic thioimides 292–294 and 295 with 2,3-dimethylbut-2-ene (215a) afforded the corresponding thietanes 296–299. However, the products were obtained together with pyrrolidinone, thiopyrrolidinone, or
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Published 22 Jun 2020

Photocatalytic trifluoromethoxylation of arenes and heteroarenes in continuous-flow

  • Alexander V. Nyuchev,
  • Ting Wan,
  • Borja Cendón,
  • Carlo Sambiagio,
  • Job J. C. Struijs,
  • Michelle Ho,
  • Moisés Gulías,
  • Ying Wang and
  • Timothy Noël

Beilstein J. Org. Chem. 2020, 16, 1305–1312, doi:10.3762/bjoc.16.111

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  • and heteroarenes. The use of flow photochemistry allows the reaction to occur 16 times faster than in batch, while at the same time achieving similar yields. Thanks to the intrinsic properties of microflow systems, especially for the scale-up of photochemical processes, we anticipate this procedure
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Published 15 Jun 2020

[3 + 2] Cycloaddition with photogenerated azomethine ylides in β-cyclodextrin

  • Margareta Sohora,
  • Leo Mandić and
  • Nikola Basarić

Beilstein J. Org. Chem. 2020, 16, 1296–1304, doi:10.3762/bjoc.16.110

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  • systems for the control of photoreactivity. Keywords: [3 + 2] cycloadditions; β-cyclodextrin; inclusion complexes; photochemistry; phthalimides; Introduction Cycloadditions are highly useful reactions in organic synthesis providing complex cyclic structures from easily available precursors [1][2]. Among
  • 6420 device. Photochemistry of 2 and 3 under different conditions A solution of 2 (30 mg, 0.11 mmol) in CH3CN (27.5 mL) was prepared and transferred to 7 quartz cuvettes (3.9 mL into each). Then, CH3CN (3.9 mL) or H2O (3.9 mL) was added to each of the cuvettes, followed by the addition of β-CD (200 mg
  • values by the WINEQNMR program [51] according to the model for the formation of 1:1 stoichiometry of the inclusion complex 2@β-CD. Irradiation of 1 in the presence of acrylonitrile (AN). Complexation of 2 with β-CD, and formation of a ternary complex AN@2@β-CD. Photochemistry of 2 in the presence of AN
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Published 12 Jun 2020

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

  • Stephanie G. E. Amos,
  • Marion Garreau,
  • Luca Buzzetti and
  • Jerome Waser

Beilstein J. Org. Chem. 2020, 16, 1163–1187, doi:10.3762/bjoc.16.103

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  • renaissance of photocatalysis. Since the early seminal reports [1][2][3][4], inspired by pioneering works in photochemistry [5][6][7], this field has attracted increasing attention, and organic chemists have developed a wide variety of photocatalytic reactions [8][9][10][11]. One of the reasons for this rapid
  • benign photocatalysts is of high importance, and organic dyes represent a powerful platform for pursuing this goal. The ability of organic dyes to absorb light and promote transformations is known since the early stage of photochemistry, and they represent attractive alternatives to the established
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Published 29 May 2020

Accelerating fragment-based library generation by coupling high-performance photoreactors with benchtop analysis

  • Quentin Lefebvre,
  • Christophe Salomé and
  • Thomas C. Fessard

Beilstein J. Org. Chem. 2020, 16, 982–988, doi:10.3762/bjoc.16.87

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  • -catalyzed cross-coupling reactions [9]. Recently, milder cross-coupling methods using more abundant and affordable metals such as nickel, in combination with photochemistry or electrochemistry, significantly improved accessibility to N-arylated complex amines [10][11][12]. Results and Discussion As we
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Published 12 May 2020

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

  • Rodrigo Costa e Silva,
  • Luely Oliveira da Silva,
  • Aloisio de Andrade Bartolomeu,
  • Timothy John Brocksom and
  • Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

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  • the last decade, photochemistry has re-emerged as a powerful tool for the scientific community. Although photochemical processes have been discovered over almost two centuries [1], only recently the scientific commuity has improved reactor technologies for the application of these processes on a large
  • continuous-flow photochemistry a sustainable alternative approach being applied already by the chemical and pharmaceutical industries. Porphyrinoid is the term given for a class of organic compounds containing four pyrrole rings connected by four methylene bridges, and include porphyrin, chlorin
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Published 06 May 2020

A method to determine the correct photocatalyst concentration for photooxidation reactions conducted in continuous flow reactors

  • Clemens R. Horn and
  • Sylvain Gremetz

Beilstein J. Org. Chem. 2020, 16, 871–879, doi:10.3762/bjoc.16.78

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  • maxima close to the absorption maximum of each catalyst. Keywords: catalyst concentration; channel height; flow chemistry; photooxidation; Introduction The renaissance of photochemistry that occurred over the last decade has been described as “old light through new windows”, and much of this work
  • sources over mercury arcs and other light sources commonly used in industry and classical synthetic organic photochemistry. LEDs typically have much narrower emission spectra when compared to these light sources, all of which have broad emission spectra except for low-pressure sodium vapor lamps [15][16
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Published 27 Apr 2020

Aldehydes as powerful initiators for photochemical transformations

  • Maria A. Theodoropoulou,
  • Nikolaos F. Nikitas and
  • Christoforos G. Kokotos

Beilstein J. Org. Chem. 2020, 16, 833–857, doi:10.3762/bjoc.16.76

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  • Maria A. Theodoropoulou Nikolaos F. Nikitas Christoforos G. Kokotos Laboratory of Organic Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Athens 15784, Greece 10.3762/bjoc.16.76 Abstract Photochemistry, the use of light to promote organic transformations, has
  • presented. Keywords: aldehyde; green chemistry; photochemistry; photoinitiation; sustainable chemistry; Introduction Photochemistry, and especially photoredox catalysis have altered the way that modern researchers treat radical species [1][2][3][4]. In most cases, a metal-based photocatalyst is employed
  • , benzaldehyde (8) has also been studied for the ability to carry out HAT processes. In 1975, Obi and co-worker studied the photochemistry of excited benzaldehyde (9) with the use of electron paramagnetic resonance (EPR) [20]. They detected that the generated radicals from this process were the α-hydroxybenzyl
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Published 23 Apr 2020

Recent advances in photocatalyzed reactions using well-defined copper(I) complexes

  • Mingbing Zhong,
  • Xavier Pannecoucke,
  • Philippe Jubault and
  • Thomas Poisson

Beilstein J. Org. Chem. 2020, 16, 451–481, doi:10.3762/bjoc.16.42

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  • organic molecules absorb light in the UV region (UV-A, UV-B, or UV-C), selectivity was a key point to address in photochemistry and photocatalysis using visible light tackled this issue. Moreover, the use of inexpensive and energy-efficient visible light-emitting diodes (LEDs) was an impressive
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Published 23 Mar 2020

Photophysics and photochemistry of NIR absorbers derived from cyanines: key to new technologies based on chemistry 4.0

  • Bernd Strehmel,
  • Christian Schmitz,
  • Ceren Kütahya,
  • Yulian Pang,
  • Anke Drewitz and
  • Heinz Mustroph

Beilstein J. Org. Chem. 2020, 16, 415–444, doi:10.3762/bjoc.16.40

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  • differ. It facilitates their use with modern light sources such LEDs and lasers with emission in the NIR between 800–1100 nm. A purposeful use requires a more detailed understanding of the photochemistry occurring in such compounds. Photophysics and photochemistry General aspects Figure 1 depicts
  • photochemistry and photophysics of NIR absorbers from the simplest point of view. Excitation based on one-photon excitation (OP) results in population of higher vibrational levels of the first excited singlet state (S1), which fast relax by vibrational relaxation into the lowest vibrational level of the S1. The
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Published 18 Mar 2020

p-Pyridinyl oxime carbamates: synthesis, DNA binding, DNA photocleaving activity and theoretical photodegradation studies

  • Panagiotis S. Gritzapis,
  • Panayiotis C. Varras,
  • Nikolaos-Panagiotis Andreou,
  • Katerina R. Katsani,
  • Konstantinos Dafnopoulos,
  • George Psomas,
  • Zisis V. Peitsinis,
  • Alexandros E. Koumbis and
  • Konstantina C. Fylaktakidou

Beilstein J. Org. Chem. 2020, 16, 337–350, doi:10.3762/bjoc.16.33

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  • radicals are also produced from 2-(1-naphthylmethyl)imidazoline [35], whereas acylaminyl radicals [R(COR)N∙] are formed from the photocleavage of the N–O bond of N,O-diacyl-N-phenylhydroxylamines, along with a carbonyloxyl radical [38]. The photochemistry of O-carbamoyl oximes (or oxime carbamates) is well
  • factor of 1.43 [11]. Theoretical calculations Calculations for the photodegradation of carbamates The structures, properties and the basic photochemistry of compounds 11 and 12 was studied using the density functional theory (DFT) method [86][87][88][89] and the functional B3PW91 along with the 6-31 G(d
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Published 09 Mar 2020

Synthesis and characterization of bis(4-amino-2-bromo-6-methoxy)azobenzene derivatives

  • David Martínez-López,
  • Amirhossein Babalhavaeji,
  • Diego Sampedro and
  • G. Andrew Woolley

Beilstein J. Org. Chem. 2019, 15, 3000–3008, doi:10.3762/bjoc.15.296

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  • . While many classes of photoswitches are known [1][2], few of these are easily adaptable to controlling targets, such as proteins [3], while simultaneously exhibiting robust photochemistry in the red or near-infrared (NIR) regions of the spectrum [4][5][6][7]. Azonium ions – protonated forms of
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Published 30 Dec 2019

Chemical tuning of photoswitchable azobenzenes: a photopharmacological case study using nicotinic transmission

  • Lorenzo Sansalone,
  • Jun Zhao,
  • Matthew T. Richers and
  • Graham C. R. Ellis-Davies

Beilstein J. Org. Chem. 2019, 15, 2812–2821, doi:10.3762/bjoc.15.274

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  • utilized further in collaboration with Lester [4][5][6], but the power of AB photochemistry for biochemistry and cell physiology was then largely forgotten until 2000, when it was revived by Woolley and co-workers in a seminal paper [7]. Since that time, AB photochromes have been exploited by many research
  • a monofluoro-AB (1FAB) [18]. Spectra in HEPES, pH 7.4 at rt. Photochemistry of 4FABTA (2), and thermodynamic stability in physiological buffer. a) Trans–cis photochemical reaction of 2. b) Absorption spectra of all trans-2 (black), cis-2 PSS (from 532 nm laser), and trans-2 PSS (from 405 nm laser
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Published 21 Nov 2019

A photochemical determination of luminescence efficiency of upconverting nanoparticles

  • Baptiste Amouroux,
  • Clément Roux,
  • Jean-Claude Micheau,
  • Fabienne Gauffre and
  • Christophe Coudret

Beilstein J. Org. Chem. 2019, 15, 2671–2677, doi:10.3762/bjoc.15.260

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  • efficiency of these green-emitting “nanolamps”. The agreement of the collected data with the previous published results validates this approach. Keywords: actinometry; diarylethene; lanthanide; photochemistry; upconverting nanoparticle; Introduction The photophysical property of converting low-energy light
  • ) imposed by the combination of medium composition (organic compound absorbing mostly in the UV–vis range) and the Beer–Lambert law. Moreover, the NIR excitation wavelengths used are much less damaging when biological applications are in sight [7]. “NIR photochemistry”, based on the upconversion phenomenon
  • sources. Since the recent renewal of photochemistry caused by the use of LEDs and microfluidic devices, actinometry has become a convenient tool to parameterize the performances of photoreactors [23][24][25]. Actinometer choice is guided by the operating conditions and by the spectral overlap between the
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Published 11 Nov 2019

A toolbox of molecular photoswitches to modulate the CXCR3 chemokine receptor with light

  • Xavier Gómez-Santacana,
  • Sabrina M. de Munnik,
  • Tamara A. M. Mocking,
  • Niels J. Hauwert,
  • Shanliang Sun,
  • Prashanna Vijayachandran,
  • Iwan J. P. de Esch,
  • Henry F. Vischer,
  • Maikel Wijtmans and
  • Rob Leurs

Beilstein J. Org. Chem. 2019, 15, 2509–2523, doi:10.3762/bjoc.15.244

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  • of medicinal chemistry and photochemistry. Classical medicinal chemistry approaches make use of small-molecule ligands binding a target protein, thereby modifying its activity. Photopharmacological approaches use light-sensitive photochromic ligands that provide an advantageous and more precise
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Published 23 Oct 2019

Experimental and computational electrochemistry of quinazolinespirohexadienone molecular switches – differential electrochromic vs photochromic behavior

  • Eric W. Webb,
  • Jonathan P. Moerdyk,
  • Kyndra B. Sluiter,
  • Benjamin J. Pollock,
  • Amy L. Speelman,
  • Eugene J. Lynch,
  • William F. Polik and
  • Jason G. Gillmore

Beilstein J. Org. Chem. 2019, 15, 2473–2485, doi:10.3762/bjoc.15.240

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  • photochemistry of two closely related and more reducible quinazolinespirohexadienones (QSHDs), wherein the naphthalene of the PSHD is replaced with a quinoline. In the present work, we report our investigation of the electrochemistry of these asymmetric QSHDs. In addition to the short wavelength and photochromic
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Published 18 Oct 2019

Azologization and repurposing of a hetero-stilbene-based kinase inhibitor: towards the design of photoswitchable sirtuin inhibitors

  • Christoph W. Grathwol,
  • Nathalie Wössner,
  • Sören Swyter,
  • Adam C. Smith,
  • Enrico Tapavicza,
  • Robert K. Hofstetter,
  • Anja Bodtke,
  • Manfred Jung and
  • Andreas Link

Beilstein J. Org. Chem. 2019, 15, 2170–2183, doi:10.3762/bjoc.15.214

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  • physicochemical properties upon irradiation with light, represent one major approach to this. One of the most common light-driven transformations exploited in molecular photoswitches is the E–Z isomerization of double bonds [18]. In this context, the photochemistry of stilbenes and the closely related azobenzenes
  • unclear. Photochemistry of azastilbenes The photochemical behaviour of stilbenes has been subject to intense investigation in the past. It is reported that unsubstituted stilbene undergoes E→Z photoisomerization [47], as well as photocyclization to dihydrophenanthrene upon UV irradiation, which is
  • are oxidized to 2- and 4-azaphenantrene (not shown), respectively [50]. Photochemistry of compounds 2b and 2f was investigated via UV–vis spectroscopy, LC–HRMS and NMR spectroscopy. Compound 2b represents the core structure of the azastilbenes investigated, whereas in 2f the influence of ortho
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Published 16 Sep 2019

1,2,3,4-Tetrahydro-1,4,5,8-tetraazaanthracene revisited: properties and structural evidence of aromaticity loss

  • Arnault Heynderickx,
  • Sébastien Nénon,
  • Olivier Siri,
  • Vladimir Lokshin and
  • Vladimir Khodorkovsky

Beilstein J. Org. Chem. 2019, 15, 2059–2068, doi:10.3762/bjoc.15.203

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  • of moisture. The photochemistry of both compounds is currently under investigation in our labs. Crystal structures Numerous short intermolecular contacts are revealed upon inspection the crystal lattice of 3, 6a and 7a. There are two independent molecules of 3 in the unit cell with slightly different
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Published 28 Aug 2019

Naphthalene diimides with improved solubility for visible light photoredox catalysis

  • Barbara Reiß and
  • Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2019, 15, 2043–2051, doi:10.3762/bjoc.15.201

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  • light range between 520 nm and 640 nm. The irradiation by visible light together with the use of an organic dye instead of a transition metal complex as photoredox catalyst improve the sustainability and make photoredox catalysis “greener”. Keywords: chromophore; dyes; electrochemistry; photochemistry
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Published 27 Aug 2019

Fluorinated azobenzenes as supramolecular halogen-bonding building blocks

  • Esther Nieland,
  • Oliver Weingart and
  • Bernd M. Schmidt

Beilstein J. Org. Chem. 2019, 15, 2013–2019, doi:10.3762/bjoc.15.197

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  • building blocks both in solution and in the solid state in combination with neutral halogen bonding acceptors, such as lutidines. Therefore, we investigate the photochemistry of a series of azobenzene photoswitches. Upon introduction of iodoethynyl groups, the halogen bonding donor properties are
  • azobenzenes with different halogen bonding donor properties are discussed in relation to their changing photophysical properties, rationalized by DFT calculations. Keywords: azobenzene; DFT calculations; fluorine chemistry; halogen bonding; photochemistry; Introduction The halogen bond is an attractive
  • boxes [35]. Therefore, we herein present a comprehensive investigation of the photochemistry of highly fluorinated azobenzenes. Our efforts are supported by theoretical calculations, showing that these azobenzenes are suitable for the use as building blocks in supramolecular architectures. Results and
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Published 23 Aug 2019

Tandem copper and photoredox catalysis in photocatalytic alkene difunctionalization reactions

  • Nicholas L. Reed,
  • Madeline I. Herman,
  • Vladimir P. Miltchev and
  • Tehshik P. Yoon

Beilstein J. Org. Chem. 2019, 15, 351–356, doi:10.3762/bjoc.15.30

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  • renewed interest in synthetic photochemistry has resulted in the discovery of a broad range of powerful new bond-forming transformations [1][2][3][4]. Much of this work has been premised on the ability of visible light-activated photocatalysts to generate highly reactive odd-electron intermediates via
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Published 05 Feb 2019

N-Arylphenothiazines as strong donors for photoredox catalysis – pushing the frontiers of nucleophilic addition of alcohols to alkenes

  • Fabienne Speck,
  • David Rombach and
  • Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2019, 15, 52–59, doi:10.3762/bjoc.15.5

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  • after 20 h of irradiation. Keywords: addition; phenothiazine; photochemistry; photoredox catalysis; redox potential; Introduction Visible-light photoredox catalysis has become a precious tool in modern synthetic organic chemistry and experiences a continuously growing interest in industrial
  • chemical redox dynamics between −2.1 V up to +2.1 V. One of the key problems in photochemistry, which was recently addressed by the development of the consecutive photoelectron transfer process (conPET) [5], is the need to push the frontiers by accessing high reduction potentials. While the classical
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Published 04 Jan 2019

Organometallic vs organic photoredox catalysts for photocuring reactions in the visible region

  • Aude-Héloise Bonardi,
  • Frédéric Dumur,
  • Guillaume Noirbent,
  • Jacques Lalevée and
  • Didier Gigmes

Beilstein J. Org. Chem. 2018, 14, 3025–3046, doi:10.3762/bjoc.14.282

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  • absorbing compound and suitable additives under light to induce a catalytical cycle. As light is an inexhaustible and renewable energy, photochemistry has dealt a great interest into organic chemistry and green chemistry since the early 20th century [15]. By absorbing light, the compound reaches an
  • photoredox catalysts The first photoredox catalysts to emerge were the metal-based complexes. Indeed, metal complexes, also named coordination compounds, have been recognized in the photochemistry field since the second half of the last century [33][34][35]. However, these compounds are still the subject of
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Published 12 Dec 2018
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