Naphthalene diimide–amino acid conjugates as novel fluorimetric and CD probes for differentiation between ds-DNA and ds-RNA

• Annike Weißenstein,
• Myroslav O. Vysotsky,
• Ivo Piantanida and
• Frank Würthner

Beilstein J. Org. Chem. 2020, 16, 2032–2045, doi:10.3762/bjoc.16.170

• the type of polynucleotide, thus the studied NDI dyes act as dual fluorimetric/ICD probes for sensing the difference between here used GC-DNA, AT-DNA and AU-RNA. Keywords: amino acid–fluorophore conjugate; circular dichroism; DNA/RNA recognition; fluorescence; intercalation; naphthalene diimide

• dyes by its ability to intercalate into ds-DNA/RNA by “threading” through the polynucleotide double helix [21][22]. Such “threading intercalation” indicates that a large aromatic moiety with bulky groups at opposite ends is inserted between two DNA or RNA base pairs, whereby bulky substituents end in

• therefore adaptable for the design of FRET pairs with other dyes along the peptide backbone. Such amino acid construct would bring a novel functional property into peptide–multichromophore systems targeting DNA/RNA. For the design of our new constructs we noticed that the majority of DNA/RNA targeting NDIs

Et₃N/DMSO-supported one-pot synthesis of highly fluorescent β-carboline-linked benzothiophenones via sulfur insertion and estimation of the photophysical properties

• Dharmender Singh,
• Vipin Kumar and
• Virender Singh

Beilstein J. Org. Chem. 2020, 16, 1740–1753, doi:10.3762/bjoc.16.146

• a variety of biological activities such as anticancer [24], inhibition of tyrosine phosphatase 1B, antioxidant properties, etc. [25][26][27]. Due to their numerous applications, they have found diverse uses such as thioindigo-like dyes, photoresponsive devices, and photoswitchable biomolecules [28

Mechanochemical green synthesis of hyper-crosslinked cyclodextrin polymers

• Alberto Rubin Pedrazzo,
• Fabrizio Caldera,
• Marco Zanetti,
• Silvia Lucia Appleton,
• Nilesh Kumar Dhakar and
• Francesco Trotta

Beilstein J. Org. Chem. 2020, 16, 1554–1563, doi:10.3762/bjoc.16.127

• crosslinker. The polymer obtained exhibited the same characteristics as a CD-based carbonate NS synthesized in a solvent. Moreover, after the synthesis, the polymer was easily functionalized through the reaction of the nucleophilic carboxylic group with three different organic dyes (fluorescein, methyl red

• nanosponges with selected organic dyes that are used as probe molecules with different structures (methyl red, rhodamine B, and fluorescein). The simple functionalization of the cyclodextrin NS, in this case via reactive imidazole moieties, is particularly interesting for a variety of applications. For

• different organic dyes. First, βNS-CDI 1:8 was purified by PSE (and so, with only reactive IM left) and accurately milled. The functionalization, as described in the experimental section, was performed in DMSO, an organic solvent in which the material was insoluble but which was suitable for reactions in an

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

• organic synthesis is dominated by homogeneous organic dyes and phosphorescent transition metal complexes [40][41][42]. This is largely due to the higher efficiency of molecular photocatalysts, which disperse in solution and can be irradiated uniformly, especially in narrow flow channels [43]. The

• components in the coating, leaving the TiO2 powder exposed [75]. In 1938, Goodeve and Kitchener used this knowledge to perform the first study on the photodegradation of organic dyes with TiO2 powder [76]. A series of subsequent reports that were historically relevant to developing TiO2- and semiconductor

• photocatalytic degradation of basic organic dyes containing sulfonate groups, remazol black 5 (3, Figure 7) and procion red MX-5B (4, Figure 7), and showed a significant enhancement of 4 adsorption when the pH value was reduced to 3 (Figure 7) [98]. The authors stated that this reflected a higher positive charge

Synthesis of new fluorescent molecules having an aggregation-induced emission property derived from 4-fluoroisoxazoles

• Kazuyuki Sato,
• Akira Kawasaki,
• Yukiko Karuo,
• Atsushi Tarui,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2020, 16, 1411–1417, doi:10.3762/bjoc.16.117

• ; Introduction Fluorescence bioprobes based on conventional organic dyes are used for enzyme activity measurements and in bioimaging systems with promising applications in the field of clinical diagnostics [1][2][3][4][5][6][7]. Most of the fluorescence bioprobes are mainly excited with near-ultraviolet or blue

Distinctive reactivity of N-benzylidene-[1,1'-biphenyl]-2-amines under photoredox conditions

• Shrikant D. Tambe,
• Kwan Hong Min,
• Naeem Iqbal and
• Eun Jin Cho

Beilstein J. Org. Chem. 2020, 16, 1335–1342, doi:10.3762/bjoc.16.114

• the yield of the 1,2-diamine product (Table 1). Among the series of photocatalysts tested, ranging from the Ru/Ir polypyridyl complexes to organic dyes, [Ir(dtbbpy)(ppy)2]PF6 was found to be the best and afforded 2a in 60% yield, along with 11% of the homocoupled product 3a (Table 1, entries 1–9). The

Anthelmintic drug discovery: target identification, screening methods and the role of open science

• Frederick A. Partridge,
• Ruth Forman,
• Carole J. R. Bataille,
• Graham M. Wynne,
• Marina Nick,
• Angela J. Russell,
• Kathryn J. Else and
• David B. Sattelle

Beilstein J. Org. Chem. 2020, 16, 1203–1224, doi:10.3762/bjoc.16.105

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

• Stephanie G. E. Amos Marion Garreau Luca Buzzetti Jerome Waser Laboratory of Catalysis and Organic Synthesis, Ecole Polytechnique Fédérale de Lausanne, EPFL, SB ISIC LCSO, BCH 4306 1015 Lausanne, Switzerland 10.3762/bjoc.16.103 Abstract Organic dyes have emerged as a reliable class of photoredox

• -, nitrogen-, oxygen-, and sulfur-centered radicals, open-shell charged species, and sensitized organic compounds. Keywords: organic dyes; photocatalysis; photoredox catalysis; radicals; reactive intermediates; Review Introduction In the last decade, synthetic organic chemistry has experienced the

• 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

Cation-induced ring-opening and oxidation reaction of photoreluctant spirooxazine–quinolizinium conjugates

• Phil M. Pithan,
• Sören Steup and
• Heiko Ihmels

Beilstein J. Org. Chem. 2020, 16, 904–916, doi:10.3762/bjoc.16.82

• +. Keywords: oxazole; oxidation; quinolizinium; spirooxazines; styryl dyes; Introduction Spiropyrans and spirooxazines are exemplary photochromic compounds that have gained great attention in the last decades because they allow to reversibly alter and control the physical and chemical properties of

• been shown that derivatives thereof have a great potential to serve as functional units in DNA-binding ligands [54], fluorescent dyes and chemosensors [55][56][57][58][59]. Furthermore, we have already demonstrated that styryl-substituted quinolizinium derivatives exhibit ideal photophysical and DNA

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

• since any pharmaceutically relevant compounds must not contain any metal contamination [5], the use of organic dyes is quite popular and can substitute the use of metal-based photocatalysts [6]. An alternative solution is the use of organic molecules as photocatalysts. There are already many reviews

Towards triptycene functionalization and triptycene-linked porphyrin arrays

• Gemma M. Locke,
• Keith J. Flanagan and
• Mathias O. Senge

Beilstein J. Org. Chem. 2020, 16, 763–777, doi:10.3762/bjoc.16.70

• essentially half a porphyrin molecule. These highly fluorescent organic compounds are a part of the difluoroboraindacene family. Owing to their versatility, they have become increasingly popular for their use as fluorophores [17][18][19]. BODIPY-based dyes have found application in many areas including

Regioselectively α- and β-alkynylated BODIPY dyes via gold(I)-catalyzed direct C–H functionalization and their photophysical properties

• Takahide Shimada,
• Shigeki Mori,
• Masatoshi Ishida and
• Hiroyuki Furuta

Beilstein J. Org. Chem. 2020, 16, 587–595, doi:10.3762/bjoc.16.53

• , while the emission quantum yields of the β-ethynylated derivatives are significantly lower than those of α-ethynylated ones. The current method should be useful for fine-tuning of the photophysical properties of BODIPY dyes as well as for constructing BODIPY-based building cores for functional π

• optical features such as intense and narrow S0–S1 absorption and emission bands in the visible-to-near-infrared region, a high fluorescence quantum yield, and good photostability. For the applications mentioned above, various BODIPY dyes functionalized at the meso-, α-, and β-pyrrolic positions have been

• -EBX reagents. This atom-economical method for the late-stage alkynylation of BODIPY dyes could be an alternate approach for functionalized fluorescent dyes without the need of preparing unstable halogenated pyrrole precursors. The resulting α- and β-ethynyl-substituted BODIPYs displayed distinct

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

• about the future availability of these metals at a reasonable cost. With regards to organic dyes, impressive developments have been achieved, but these catalysts might suffer from a low photochemical stability, and thus hampering their use and recyclability [7]. Therefore, alternative solutions have to

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

• meso-position comprising either electron-donating or electron-withdrawing substituents complement the design of tailor made absorption [52][53][54]. The fact that many investigations were pursued in the visible range assigned these materials in general as dyes, which should not be correct. The term dye

• shown to realize photoinitiated controlled/living radical polymerization of various monomers in metal free conditions. In the visible region, several dyes (fluorescein, eosin Y, erythrosin B) worked well to mediate ATRP in the presence of amines [72]. The reversibility of the electron transfer steps

Visible-light-induced addition of carboxymethanide to styrene from monochloroacetic acid

• Kaj M. van Vliet,
• Nicole S. van Leeuwen,
• Albert M. Brouwer and
• Bas de Bruin

Beilstein J. Org. Chem. 2020, 16, 398–408, doi:10.3762/bjoc.16.38

• compound, with applications ranging from thickening agents (carboxymethyl cellulose, E466) [1][2], herbicides (2,4-dichlorophenoxyacetic acid), cosmetics (cocamidopropyl betaine), dyes (indigo vat dye) [3], to pharmaceuticals (ibuprofen, glycine, malonates) [4] (see Figure 1). Many reactions with

Recent developments in photoredox-catalyzed remote ortho and para C–H bond functionalizations

• Rafia Siddiqui and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 248–280, doi:10.3762/bjoc.16.26

• complexes and organic dyes involved [30]. Inspiring work by Pac, Kellog, Deronzier, and Sauvage on novel organic syntheses were focused on radical generation via photoredox catalysis, which has advanced C–H functionalizations to a higher level [31][32][33][34]. However, a major contribution to the

• = C, B, N, O, S) bonds for architecturally simple, yet challenging molecules, which are otherwise highly difficult or impossible to be formed by other methods. These practices count on the competence of metal complexes and organic dyes to convert visible light into chemical energy via SET events

• disappearance of phosphorescence, following the Frank–Condon principle [44][45]. As far as the singlet and triplet excited states of organic dyes and organometallic compounds are concerned, there is a difference in lifetimes. Usually, the lifetime of excited states of organic dyes is nanoseconds, whereas for

Reversible photoswitching of the DNA-binding properties of styrylquinolizinium derivatives through photochromic [2 + 2] cycloaddition and cycloreversion

• Sarah Kölsch,
• Heiko Ihmels,
• Jochen Mattay,
• Norbert Sewald and
• Brian O. Patrick

Beilstein J. Org. Chem. 2020, 16, 111–124, doi:10.3762/bjoc.16.13

• switching of binding properties [36]. Apparently, styryl-substituted aromatic derivatives could fill this gap because the [2 + 2] photocyclization reaction of stilbenes and derivatives thereof is a well-established reversible photoreaction [37][38][39][40][41][42][43][44][45][46], and styryl dyes, in

• particular cationic ones, were shown to be efficient DNA binders [47][48][49][50][51][52][53][54][55][56][57][58]. Nevertheless, the photochromic nature of DNA-binding styryl dyes has not been applied to use them as photoswitchable DNA binders. Although, there is one reported example that demonstrates the

• concentration, i.e., at larger LDR, the ligands tended to form aggregates, as commonly observed for donor–acceptor dyes, that stacked along the grooves of DNA. Photocycloaddition reactions The photochemical properties of the derivatives 3a–d were investigated. Firstly, the substrates were irradiated in

Synthesis and optoelectronic properties of benzoquinone-based donor–acceptor compounds

• Daniel R. Sutherland,
• Nidhi Sharma,
• Georgina M. Rosair,
• Ifor D. W. Samuel,
• Ai-Lan Lee and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2019, 15, 2914–2921, doi:10.3762/bjoc.15.285

• benzoquinones have found utility in a variety of different fields, such as medicinal chemistry [3], natural products [4], dyes [5], ligands [6][7][8][9], oxidation chemistry [10], functional materials [11], and molecular electronics [12][13]. Due to their myriad applications, one of our groups recently

One-pot synthesis of substituted pyrrolo[3,4-b]pyridine-4,5-diones based on the reaction of N-(1-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-2-oxo-2-arylethyl)acetamide with amines

• Valeriya G. Melekhina,
• Andrey N. Komogortsev,
• Boris V. Lichitsky,
• Vitaly S. Mityanov,
• Artem N. Fakhrutdinov,
• Arkady A. Dudinov,
• Vasily A. Migulin,
• Yulia V. Nelyubina,
• Elizaveta K. Melnikova and
• Michail M. Krayushkin

Beilstein J. Org. Chem. 2019, 15, 2840–2846, doi:10.3762/bjoc.15.277

• , Moscow 119991, Russian Federation Department of Fine Organic Synthesis and Chemistry of Dyes, D. Mendeleyev University of Chemical Technology of Russia, Miusskaya Sq., 9, Moscow 125047, Russian Federation A. N. Nesmeyanov Institute of Organoelement Compounds, Vavilova St., 28, Moscow 119991, Russian

Design, synthesis and investigation of water-soluble hemi-indigo photoswitches for bioapplications

• Daria V. Berdnikova

Beilstein J. Org. Chem. 2019, 15, 2822–2829, doi:10.3762/bjoc.15.275

• new biocompatible photochromes with complementary properties is highly desirable to speed up the progress in this important field. In this context, an emerging class of hemi-indigo photoswitches attracted special attention [12][13][14][15][16][17]. Despite the fact that the hemi-indigo dyes are known

• responsible for the rate of thermal E–Z isomerization pointing out the importance of the Coulomb interactions between hemi-indigo and buffer components. A possible explanation of this observation can be provided by the comparison with structurally related hemi(thio)indigo dyes [22]. Thus, in the case of hemi

Dyes in modern organic chemistry

• Heiko Ihmels

Beilstein J. Org. Chem. 2019, 15, 2798–2800, doi:10.3762/bjoc.15.272

• Heiko Ihmels University of Siegen, Department of Chemistry and Biology, and Center of Micro- and Nanochemistry and Engineering, Adolf-Reichwein-Str. 2, 57068 Siegen, Germany 10.3762/bjoc.15.272 Keywords: dyes; Research on organic dyes constitutes a cornerstone in organic chemistry. It started

• between research on dyes and industrial chemistry [2][3][4]. As a result, the success and strength of several chemical companies are originally based on dye chemistry. Although the traditional dyeing of textiles, hair, food, cosmetics, photography or printer colors, etc. is still highly relevant, organic

• dyes also contribute as essential components in modern applications such as in OLEDs [5][6], solar cells [7][8], organic semiconductors [9], NLO materials [10], photopolymerization [11], or Chemistry 4.0 [12]. From its very beginning, dye chemistry is strongly connected to the scientific developments

Diversity-oriented synthesis of spirothiazolidinediones and their biological evaluation

• Sambasivarao Kotha,
• Gaddamedi Sreevani,
• Lilya U. Dzhemileva,
• Milyausha M. Yunusbaeva,
• Usein M. Dzhemilev and
• Vladimir A. D’yakonov

Beilstein J. Org. Chem. 2019, 15, 2774–2781, doi:10.3762/bjoc.15.269

• , phosphatidylserine molecules appear on the cell surface but the membrane is still impermeable for DNA-binding dyes (such as propidium iodide). The membrane integrity is lost at later stages of the cell death. Thus, while detecting the apoptosis, one can distinguish four types of cells: living cells (annexin V−/PI

Emission solvatochromic, solid-state and aggregation-induced emissive α-pyrones and emission-tuneable 1H-pyridines by Michael addition–cyclocondensation sequences

• Natascha Breuer,
• Irina Gruber,
• Christoph Janiak and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2019, 15, 2684–2703, doi:10.3762/bjoc.15.262

• increasingly used in OLEDs [6][7][8][9][10] and LCDs [11][12][13] of mobile phones [14]. Fluorescent compounds often intensively emit in solution but only weakly or not in the solid state [15]. Dyes which fluoresce both in the solid state and in solution are still relatively rare, due to the fact that often

• fluorophores [19], in particular on aggregation-induced emissive polar dyes [20]. Conceptually, many of these consecutive multicomponent syntheses rely on transition-metal-catalyzed heterocyclic syntheses [21]. By virtue of catalytic generation of alkynones [22] we have recently disclosed consecutive

Synthesis of aryl-substituted thieno[3,2-b]thiophene derivatives and their use for N,S-heterotetracene construction

• Nadezhda S. Demina,
• Nikita A. Kazin,
• Nikolay A. Rasputin,
• Roman A. Irgashev and
• Gennady L. Rusinov

Beilstein J. Org. Chem. 2019, 15, 2678–2683, doi:10.3762/bjoc.15.261

• light-harvesting dyes for dye-sensitized solar cells [1], electron-donating materials for bulk heterojunction solar cells [2][3][4], and p-type semiconductors for organic field-effect transistors [5][6][7]. Within the same context of organic semiconductor development, the bicyclic TT subunit has been

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

• diamminetetrakis(thiocyanato)chromate(III)), photochromic dyes have been proposed for such a purpose, mainly from the azobenzene, fulgide or diarylethene families [22]. The latter two are particularly attractive for visible light wavelengths above 400 nm. However, their use is conditioned by their availability and

• (Figure 1) [25][27]. Switching of such diarylethene dyes in both directions (ring closure/coloration or ring opening/discoloration) by UCNPs has been documented for years, with a seminal work reported in 2009 by the team of Branda [28]. In the following we will show how this photochromic compound can be

• particles (70 nm) [34] and recruiting the flavin-containing coenzymes as 1O2 sensitizers. In the skin, typical number of dyes per femtoliter is expected to be 750. This would correspond to an absorbance of 0.0014 in 1 cm of pure water according to a molar extinction coefficient of ca. 11300 L mol−1 cm−1. To