N-doped carbon dots covalently functionalized with pillar[5]arenes for Fe³⁺ sensing

• Jia Gao,
• Ming-Xue Wu,
• Dihua Dai,
• Zhi Cai,
• Yue Wang,
• Wenhui Fang,
• Yan Wang and
• Ying-Wei Yang

Beilstein J. Org. Chem. 2019, 15, 1262–1267, doi:10.3762/bjoc.15.123

• ) as a rising star in fluorescent nanomaterials have attracted wide attention in terms of preparation and application [1][2][3][4]. Fluorescent C-dots possess advantages over organic dyes and traditional semiconductor quantum dots due to their high solubility, facile modification, desirable chemical

Selective benzylic C–H monooxygenation mediated by iodine oxides

• Kelsey B. LaMartina,
• Haley K. Kuck,
• Linda S. Oglesbee,
• Asma Al-Odaini and
• Nicholas C. Boaz

Beilstein J. Org. Chem. 2019, 15, 602–609, doi:10.3762/bjoc.15.55

• hypervalent iodine oxidants to mediate benzylic C–H oxidation is one area experiencing a surge of interest [22][23][24][25][26][27][28][29][30][31][32][33]. Nonmetal-based benzylic oxidations have also been mediated by species including, but not limited to, electron deficient quinones, photoexcited organic

• dyes and transition metal complexes, hypohalous acids, and persulfate anions [12][34][35][36][37][38][39][40]. An important class of catalyzed benzylic C–H to C–O transformations are those catalyzed by N-oxyl radicals. Specifically, N-oxyl radical catalysts based upon the N-hydroxyphthalimide (NHPI

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

• ]. The photochemical reactivity can be tuned by the absorption and excited state characteristics of the photocatalyst. In this context, organic dyes represent a perfectly suited class of photocatalysts as they can easily be modified by the introduction of functional groups that allow fine-tuning the

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

• Michael K. Bogdos,
• Emmanuel Pinard and
• John A. Murphy

Beilstein J. Org. Chem. 2018, 14, 2035–2064, doi:10.3762/bjoc.14.179

• 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

• mechanistic considerations are highlighted in the text when appropriate. Keywords: C–H functionalisation; heterocycles; late-stage functionalisation; medicinal chemistry; organic dyes; organic photocatalysts; peptide chemistry; photoredox catalysis; Review 1 Introduction 1.1 Main advantages of

Photocatalytic formation of carbon–sulfur bonds

• Alexander Wimmer and
• Burkhard König

Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4

• . Photoredox-active metal complexes or organic dyes are used to initiate photo-induced single-electron transfer (SET) processes upon excitation with visible-light. Such photooxidations or photoreductions yield reactive organic radicals, which can undergo unique bond forming reactions, under very mild

Synthesis and application of trifluoroethoxy-substituted phthalocyanines and subphthalocyanines

• Satoru Mori and
• Norio Shibata

Beilstein J. Org. Chem. 2017, 13, 2273–2296, doi:10.3762/bjoc.13.224

• –vis spectrum, do not aggregate in solution. These dyes are expected to be developed into medical imaging probes. Phthalocyanine is expected to be used not only as a biological imaging agent but also in cancer treatment. Photodynamic therapy (PDT) is a laser cancer therapy that introduces organic dyes

Oxidative dehydrogenation of C–C and C–N bonds: A convenient approach to access diverse (dihydro)heteroaromatic compounds

• Santanu Hati,
• Ulrike Holzgrabe and
• Subhabrata Sen

Beilstein J. Org. Chem. 2017, 13, 1670–1692, doi:10.3762/bjoc.13.162

• an important class of compounds [1]. A large variety of such compounds are discovered so far and their therapeutic potential in diverse disease models has been thoroughly investigated [2]. For example thiazoles and oxazoles are found in various bioactive natural products, organic dyes and

Interactions between photoacidic 3-hydroxynaphtho[1,2-b]quinolizinium and cucurbit[7]uril: Influence on acidity in the ground and excited state

• Jonas Becher,
• Daria V. Berdnikova,
• Darinka Dzubiel,
• Heiko Ihmels and
• Phil M. Pithan

Beilstein J. Org. Chem. 2017, 13, 203–212, doi:10.3762/bjoc.13.23

• ] hosts with high affinity [6]. In most cases, this complexation strongly affects the chemical or physical properties of the ligand. For example, it was demonstrated that the optical properties of organic dyes may be modified drastically upon complexation in the CB cavity [7]. At the same time, this

New synthetic strategies for xanthene-dye-appended cyclodextrins

• Milo Malanga,
• Andras Darcsi,
• Mihaly Balint,
• Gabor Benkovics,
• Tamas Sohajda and
• Szabolcs Beni

Beilstein J. Org. Chem. 2016, 12, 537–548, doi:10.3762/bjoc.12.53

• model for the supramolecular assembly is also in agreement with previous data about the inclusion complexation of organic dyes with β-CD dimers [26]. In more detail, the analysis of the 2D ROESY spectrum reveals that the methyl units of the rhodamine side chains that resonate at 0.81 ppm (the side

Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis

• David W. Manley and
• John C. Walton

Beilstein J. Org. Chem. 2015, 11, 1570–1582, doi:10.3762/bjoc.11.173

• , uncommon reaction sequences. Homogeneous PRCs form one class that encompasses soluble organic dyes [1] as well as transition metal complexes; particularly those of Ru and Ir. Study of the latter markedly escalated from 2008 thanks to papers from the groups of MacMillan [2], Yoon [3] and Stephenson [4]. The

New palladium–oxazoline complexes: Synthesis and evaluation of the optical properties and the catalytic power during the oxidation of textile dyes

• Rym Hassani,
• Mahjoub Jabli,
• Yakdhane Kacem,
• Jérôme Marrot,
• Damien Prim and
• Béchir Ben Hassine

Beilstein J. Org. Chem. 2015, 11, 1175–1186, doi:10.3762/bjoc.11.132

• complexes was evaluated for the first time during the degradation of organic dyes such as Eriochrome Blue Black B referred to as Erio which was chosen as an example of azo dyes (Figure 1). Results and Discussion The use of oxazolines as ligands during the preparation of optically active cyclopalladated

A hybrid electron donor comprising cyclopentadithiophene and dithiafulvenyl for dye-sensitized solar cells

• Gleb Sorohhov,
• Chenyi Yi,
• Michael Grätzel,
• Silvio Decurtins and
• Shi-Xia Liu

Beilstein J. Org. Chem. 2015, 11, 1052–1059, doi:10.3762/bjoc.11.118

• ]. Although devices with the most commonly used dyes based on polypyridyl transition-metal complexes show excellent photovoltaic performances with high power conversion efficiencies of over 11% [4], metal-free organic dyes have significant advantages in several aspects. These comprise for example large molar

• extinction coefficients, ease of synthesis, fine-tuning of structural and electronic properties, and low-cost production [1][2][3][4]. Particularly, the hitherto best DSSC based on organic sensitizers shows an efficiency of 10.3% [5]. Among the most efficient organic dyes are those featured with an electron

• other hand, the presence of side chains on both DTF and CPDT moieties could prevent dye aggregation and thus retard charge recombination. Herein, we describe the preparation, characterization and the electronic properties of two new organic dyes as well as their application in DSSCs. Results and

Design, synthesis and photochemical properties of the first examples of iminosugar clusters based on fluorescent cores

• Mathieu L. Lepage,
• Antoine Mirloup,
• Manon Ripoll,
• Fabien Stauffert,
• Anne Bodlenner,
• Raymond Ziessel and
• Philippe Compain

Beilstein J. Org. Chem. 2015, 11, 659–667, doi:10.3762/bjoc.11.74

• life time (τ = 3.38 ns) are also in favor of a singlet emitting state. The excitation spectra did display a slight shift compared to the absorption spectra. This may be due to the presence of some aggregates, a problem frequently encountered with aromatic organic dyes in aqueous solutions [69][70

Eosin Y-catalyzed visible-light-mediated aerobic oxidative cyclization of N,N-dimethylanilines with maleimides

• Zhongwei Liang,
• Song Xu,
• Wenyan Tian and
• Ronghua Zhang

Beilstein J. Org. Chem. 2015, 11, 425–430, doi:10.3762/bjoc.11.48

• and not sustainable. Similar to the redox properties of these organometallic complexes, some metal-free organic dyes such as Eosin Y, Rose Bengal, Fluorescein, and Methylene Blue, have shown superiority of their applications as photocatalysts, which are easy to handle, environmentally friendly

• light (two 9 W blue LEDs) at room temperature. Gratifyingly, the desired product tetrahydroquinoline 3a was obtained in 82% yield after 18 h (Table 1, entry 1). We screened a number of metal-free organic dyes for photocatalysts. Of the dyes screened, Eosin Y showed the highest efficiency (Table 1, entry

Visible-light photoredox catalyzed synthesis of pyrroloisoquinolines via organocatalytic oxidation/[3 + 2] cycloaddition/oxidative aromatization reaction cascade with Rose Bengal

• Carlos Vila,
• Jonathan Lau and
• Magnus Rueping

Beilstein J. Org. Chem. 2014, 10, 1233–1238, doi:10.3762/bjoc.10.122

• [32]. Despite these elegant and important syntheses of pyrrolo[2,1-a]isoquinolines through dipolar [3 + 2] cycloaddition, the development of metal-free syntheses using visible light photoredox catalysis with simple organic dyes remained unexplored. Visible-light photoredox catalysis has emerged as an

• use of organic dyes as photoredox catalysts [40][41][42] has been demonstrated by several groups [43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61] and became a useful alternative to the inorganic photoredox catalysts that are expensive and sometimes toxic. The organic dyes

• the selectivity of the reaction to the aromatized product 3aa, N-bromosuccinimide was added to the reaction mixture when the starting materials were completely consumed [29][30][31][73]. In this case the desired product 3aa was obtained in 72% yield (Table 1, entry 1). Other organic dyes such as

Direct C–H trifluoromethylation of di- and trisubstituted alkenes by photoredox catalysis

• Ren Tomita,
• Yusuke Yasu,
• Takashi Koike and
• Munetaka Akita

Beilstein J. Org. Chem. 2014, 10, 1099–1106, doi:10.3762/bjoc.10.108

• ]2+ (bpy: 2,2’-bipyridine)), the relevant Ir cyclometalated complexes (e.g., fac-Ir(ppy)3 (ppy: 2-phenylpyridine)) and organic dyes has been developed; the trifluoromethyl radical (·CF3) can be easily generated from conventional CF3 radical precursors such as CF3I, CF3SO2Cl and CF3SO2Na through

Organic synthesis using photoredox catalysis

• Axel G. Griesbeck

Beilstein J. Org. Chem. 2014, 10, 1097–1098, doi:10.3762/bjoc.10.107

• other Ru or Ir complexes) with strong MLCT transitions, organic dyes such as xanthene, porphyrine or phthalocyanine dyes (e.g., eosin Y), and colloidal semiconductor particles (e.g., TiO2) [1][2][3][4][5][6][7][8][9]. In addition, combinations of light-absorbing materials have been studied such as dye

On the mechanism of photocatalytic reactions with eosin Y

• Michal Majek,
• Fabiana Filace and
• Axel Jacobi von Wangelin

Beilstein J. Org. Chem. 2014, 10, 981–989, doi:10.3762/bjoc.10.97

• acidity of most Brønsted acids in DMSO [28]. These observations lead to the conclusion that photoredox reactions catalyzed by eosin Y (or similar organic dyes) cannot be discussed without strict specification of the employed form of the dye and the reaction conditions. Conclusive mechanistic proposals of

Tailoring of organic dyes with oxidoreductive compounds to obtain photocyclic radical generator systems exhibiting photocatalytic behavior

• Christian Ley,
• Julien Christmann,
• Ahmad Ibrahim,
• Luciano H. Di Stefano and
• Xavier Allonas

Beilstein J. Org. Chem. 2014, 10, 936–947, doi:10.3762/bjoc.10.92

Metal and metal-free photocatalysts: mechanistic approach and application as photoinitiators of photopolymerization

• Jacques Lalevée,
• Sofia Telitel,
• Pu Xiao,
• Marc Lepeltier,
• Frédéric Dumur,
• Fabrice Morlet-Savary,
• Didier Gigmes and
• Jean-Pierre Fouassier

Beilstein J. Org. Chem. 2014, 10, 863–876, doi:10.3762/bjoc.10.83

• suggest that their behavior as PICs is not straightforward. The redox processes with organic dyes are not always fully reversible: this plays a detrimental role in the catalytic cycle with a lost of the efficiency through a PIC degradation. A striking example concerns the use of a Ru complex (Ru(bpy)32

The chemistry of amine radical cations produced by visible light photoredox catalysis

• Jie Hu,
• Jiang Wang,
• Theresa H. Nguyen and
• Nan Zheng

Beilstein J. Org. Chem. 2013, 9, 1977–2001, doi:10.3762/bjoc.9.234

• ). Therefore, a photocatalyst is often required to initialize electron-transfer reactions with amines. Some of the frequently used photocatalysts include ruthenium [24][25][26] and iridium [27][28] polypyridyl complexes as well as organic dyes [29][30] that are absorbed in the visible-light region. They all

Simple and rapid hydrogenation of p-nitrophenol with aqueous formic acid in catalytic flow reactors

• Rahat Javaid,
• Shin-ichiro Kawasaki,
• Akira Suzuki and
• Toshishige M. Suzuki

Beilstein J. Org. Chem. 2013, 9, 1156–1163, doi:10.3762/bjoc.9.129

• have studied flow reactions, including the decomposition of hydrogen peroxide, oxidation of organic dyes, carbon–carbon coupling, and conversion of formic acid to hydrogen (H2) and carbon dioxide (CO2), using catalytic tubular reactors [10][11][12][13]. p-Aminophenol is an important intermediate