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Search for "visible" in Full Text gives 616 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Multiswitchable photoacid–hydroxyflavylium–polyelectrolyte nano-assemblies

  • Alexander Zika and
  • Franziska Gröhn

Beilstein J. Org. Chem. 2021, 17, 166–185, doi:10.3762/bjoc.17.17

Graphical Abstract
  • visible, that is, one predominant assembly size. The size differs depending on the cycle and cycle step, lying between a hydrodynamic radius of RH = 142 nm and RH = 332 nm; that is, significant size changes occur upon triggering. A second smaller peak that in some samples occurs at higher relaxation times
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Published 19 Jan 2021

Insight into functionalized-macrocycles-guided supramolecular photocatalysis

  • Minzan Zuo,
  • Krishnasamy Velmurugan,
  • Kaiya Wang,
  • Xueqi Tian and
  • Xiao-Yu Hu

Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15

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  • of the reactant of 300 mM, ≥93% selectivity), with H2 liberation being achieved by visible-light irradiation in an aqueous solution. In comparison, CdS–CD was a highly efficient photocatalyst for benzyl alcohol dehydrogenation (77 µmol H2 in 180 h) compared to the CD-free CdS (5.4 µmol H2 in 30 h
  • , Yagi, et al. reported that the visible-light-driven hydrogen evolution of the supramolecular system could be achieved by the host–guest complexation between the cobaloxime CoPyS and γ-CD (Figure 10) [30]. Upon visible-light irradiation, the CoPyS:γ-CD 1:1 complex exhibited an enhanced photocatalytic H2
  • ) photopolymerization under visible-light irradiation in an aqueous solution [48]. Briefly, the supramolecular PDI–CB[7] complex in Figure 15 acts as a photocatalyst at a low concentration (1 ppm relative to the monomer), which could be utilized for the preparation of a series of homo- or block copolymers with an
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Published 18 Jan 2021

Synthesis, crystal structures and properties of carbazole-based [6]helicenes fused with an azine ring

  • Daria I. Tonkoglazova,
  • Anna V. Gulevskaya,
  • Konstantin A. Chistyakov and
  • Olga I. Askalepova

Beilstein J. Org. Chem. 2021, 17, 11–21, doi:10.3762/bjoc.17.2

Graphical Abstract
  • electroactive materials [52][53][54]. Carbazole-based [6]helicenes [42] and [7]helicenes [50] showed deep blue electroluminescence and have been investigated in OLED devices. Some carbazole-based [5]- and [6]helicenes have been used as visible light photoinitiators for cationic and radical polymerization [41
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Published 04 Jan 2021

Synthesis of tetrafluorinated piperidines from nitrones via a visible-light-promoted annelation reaction

  • Vyacheslav I. Supranovich,
  • Igor A. Dmitriev and
  • Alexander D. Dilman

Beilstein J. Org. Chem. 2020, 16, 3104–3108, doi:10.3762/bjoc.16.260

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  • from nitrones and a fluorinated building block is described. The annelation is based on a sequence of visible-light-promoted redox processes and a substitution reaction, and involves the cleavage of the N–O bond. The construction of tetrafluorinated piperidines from nitrones. The scope of the
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Published 29 Dec 2020

UV resonance Raman spectroscopy of the supramolecular ligand guanidiniocarbonyl indole (GCI) with 244 nm laser excitation

  • Tim Holtum,
  • Vikas Kumar,
  • Daniel Sebena,
  • Jens Voskuhl and
  • Sebastian Schlücker

Beilstein J. Org. Chem. 2020, 16, 2911–2919, doi:10.3762/bjoc.16.240

Graphical Abstract
  • pyrrole ring, which leads to different optical absorption properties in the UV–visible range (see Figure 1). Based on the UV–vis absorption spectrum, we expect a stronger resonance enhancement for GCI than GCP at 244 nm excitation due to its higher absorbance. Again, a 244 nm excitation is necessary for
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Published 27 Nov 2020

Selective recognition of ATP by multivalent nano-assemblies of bisimidazolium amphiphiles through “turn-on” fluorescence response

  • Rakesh Biswas,
  • Surya Ghosh,
  • Shubhra Kanti Bhaumik and
  • Supratim Banerjee

Beilstein J. Org. Chem. 2020, 16, 2728–2738, doi:10.3762/bjoc.16.223

Graphical Abstract
  • -aggregates. Furthermore, a visible change in morphology for the co-aggregates was observed from FESEM images (Figure 3b). All these results, taken together, indicated that the nanoaggregates were able to recognize ATP in a multivalent fashion leading to the formation of larger co-aggregates. On the contrary
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Published 10 Nov 2020

Optical detection of di- and triphosphate anions with mixed monolayer-protected gold nanoparticles containing zinc(II)–dipicolylamine complexes

  • Lena Reinke,
  • Julia Bartl,
  • Marcus Koch and
  • Stefan Kubik

Beilstein J. Org. Chem. 2020, 16, 2687–2700, doi:10.3762/bjoc.16.219

Graphical Abstract
  • response was observed to hydrogenphosphate (and hydrogenarsenate). Other oxoanions and halides induced no visible effects and also did not interfere in diphosphate and triphosphate sensing when simultaneously present. It should be noted that other strategies of detecting diphosphate anions by using
  • , this signal became smaller and two doublets appeared at lower ppm values. Once the concentration of the zinc salt exceeded a certain value, only these doublets were still visible. In addition, zinc complexation also affected the aromatic signals of the DPA ligands. The spectral changes observed in the
  • , turned out to be slightly more sensitive than NP10-Zn. In this case, the presence of phosphates mainly caused color changes of the solution, but fine precipitates were also visible. These precipitates appeared when the concentrations of diphosphate and triphosphate amounted to 10 μmol/L, and disappeared
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Published 02 Nov 2020

Synthesis of 4-substituted azopyridine-functionalized Ni(II)-porphyrins as molecular spin switches

  • Jannis Ludwig,
  • Tobias Moje,
  • Fynn Röhricht and
  • Rainer Herges

Beilstein J. Org. Chem. 2020, 16, 2589–2597, doi:10.3762/bjoc.16.210

Graphical Abstract
  • )-porphyrins; photoswitch; record player molecules; spin state; spin switch; Introduction Molecular spin switches operated with visible light in homogeneous solution [1] or on surfaces [2], hold promise for a number of hitherto unprecedented applications such as switchable contrast agents [3][4][5][6][7
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Published 21 Oct 2020

Thermodynamic and electrochemical study of tailor-made crown ethers for redox-switchable (pseudo)rotaxanes

  • Henrik Hupatz,
  • Marius Gaedke,
  • Hendrik V. Schröder,
  • Julia Beerhues,
  • Arto Valkonen,
  • Fabian Klautzsch,
  • Sebastian Müller,
  • Felix Witte,
  • Kari Rissanen,
  • Biprajit Sarkar and
  • Christoph A. Schalley

Beilstein J. Org. Chem. 2020, 16, 2576–2588, doi:10.3762/bjoc.16.209

Graphical Abstract
  • hand, additional π–π-interactions of the phenyl ring in A1·PF6 to the crown ether aromatic rings favor the complex formation. On the other hand, the flexibility of the alkyl substituent in A2·PF6 is diminished upon complexation, inducing a larger entropic penalty visible in the overall more negative
  • contrast, no charge-transfer band is present, neither for NDIRot nor for NDIC8, ruling out the formation of similar charge-transfer complexes in NDIC8 or in the corresponding rotaxane. After one-electron reduction (NDI → NDI•−), a complex absorption band pattern emerges in the visible region of all three
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Published 20 Oct 2020

Water-soluble host–guest complexes between fullerenes and a sugar-functionalized tribenzotriquinacene assembling to microspheres

  • Si-Yuan Liu,
  • Xin-Rui Wang,
  • Man-Ping Li,
  • Wen-Rong Xu and
  • Dietmar Kuck

Beilstein J. Org. Chem. 2020, 16, 2551–2561, doi:10.3762/bjoc.16.207

Graphical Abstract
  • -fullerene in co-organic solvents and aqueous solution was investigated by fluorescence spectroscopy and ultraviolet-visible spectroscopy. The association stoichiometry of the complexes TBTQ-(OG)6 with C60 and TBTQ-(OG)6 with C70 was found to be 1:1 with binding constants of Ka = (1.50 ± 0.10) × 105 M−1 and
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Published 14 Oct 2020

NMR Spectroscopy of supramolecular chemistry on protein surfaces

  • Peter Bayer,
  • Anja Matena and
  • Christine Beuck

Beilstein J. Org. Chem. 2020, 16, 2505–2522, doi:10.3762/bjoc.16.203

Graphical Abstract
  • using shaped pulses that are specific for the respective side chain nitrogen atom (≈33 ppm for Lys Nζ and ≈85 ppm for Arg Nε). N-terminal glycine residues are also visible in the Lys-specific spectrum because the chemical shifts of the CαH2-NH3+ moiety also match the selected chemical shift range. Not
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Published 09 Oct 2020

Dawn of a new era in industrial photochemistry: the scale-up of micro- and mesostructured photoreactors

  • Emine Kayahan,
  • Mathias Jacobs,
  • Leen Braeken,
  • Leen C.J. Thomassen,
  • Simon Kuhn,
  • Tom van Gerven and
  • M. Enis Leblebici

Beilstein J. Org. Chem. 2020, 16, 2484–2504, doi:10.3762/bjoc.16.202

Graphical Abstract
  • microcapillaries range from 10 µm to 1 mm. The microcapillary films are transparent to UV and visible light. Furthermore, they have a refractive index close to water (≈1.33), which makes them good candidates for photochemical reactors. In one study, those microcapillary films were used for the photodegradation of
  • LEDs and as a result decrease the efficiency of the LEDs [66]. LEDs are usually preferred to illuminate microstructured photoreactors due to their small size, monochromaticity, and adjustable power. LEDs are also the most efficient light sources in the visible range [67]. Roibu et al. designed LED
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Published 08 Oct 2020

Recent developments in enantioselective photocatalysis

  • Callum Prentice,
  • James Morrisson,
  • Andrew D. Smith and
  • Eli Zysman-Colman

Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197

Graphical Abstract
  • electron transfer (SET) steps photoinitiated using visible light as the energy source, often leading to the generation of radicals and subsequent reaction of these radicals with the ground-state substrates [3]. Energy transfer catalysis is another significant branch of photocatalysis, in which
  • ][33]. When an alkylating agent containing an aryl ring 40 (e.g., phenacyl/benzyl bromides) is used, the enamine intermediate 41 forms a coloured electron-donor acceptor (EDA) complex that can absorb visible light via an intermolecular charge-transfer state (EDA route) [14][34]. Mechanistic
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Published 29 Sep 2020

Host–guest interaction of cucurbit[8]uril with oroxin A and its effect on the properties of oroxin A

  • Zhishu Zeng,
  • Jun Xie,
  • Guangyan Luo,
  • Zhu Tao and
  • Qianjun Zhang

Beilstein J. Org. Chem. 2020, 16, 2332–2337, doi:10.3762/bjoc.16.194

Graphical Abstract
  • in the case of an excess of OA, the port interactions and inclusion interactions of OA andQ[8] can exist simultaneously. To further determine the host–guest ratio of the inclusion complex formed by Q[8] and OA, their interaction was investigated using UV–visible absorption spectroscopy via a molar
  • ratio method and Job's method. Figure 3A shows the UV–visible absorption spectra of the interaction between Q[8] and OA. It can be seen that the UV absorption of OA at 275 nm and 316 nm decreased significantly as the concentration of Q[8] was increased. When n(Q[8])/n(OA) = 1, there was a clear
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Published 22 Sep 2020

Styryl-based new organic chromophores bearing free amino and azomethine groups: synthesis, photophysical, NLO, and thermal properties

  • Anka Utama Putra,
  • Deniz Çakmaz,
  • Nurgül Seferoğlu,
  • Alberto Barsella and
  • Zeynel Seferoğlu

Beilstein J. Org. Chem. 2020, 16, 2282–2296, doi:10.3762/bjoc.16.189

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  • with different polarities and showed absorption in the visible region and green-red emission with low quantum yields. The absorption and the emission maxima were shifted bathocromically by increasing the solvent’s polarity. However, there was no correlation with the polarity parameters of the solvents
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Published 14 Sep 2020

The B & B approach: Ball-milling conjugation of dextran with phenylboronic acid (PBA)-functionalized BODIPY

  • Patrizia Andreozzi,
  • Lorenza Tamberi,
  • Elisamaria Tasca,
  • Gina Elena Giacomazzo,
  • Marta Martinez,
  • Mirko Severi,
  • Marco Marradi,
  • Stefano Cicchi,
  • Sergio Moya,
  • Giacomo Biagiotti and
  • Barbara Richichi

Beilstein J. Org. Chem. 2020, 16, 2272–2281, doi:10.3762/bjoc.16.188

Graphical Abstract
  • formazan dye with absorption characteristics in the visible region. Cells were incubated with Dex-1b at different concentrations. After 24 h the cells were washed and 135 μL fresh medium with 15 μL of MTT (at 5 mg/mL in PBS) were added to each well. Culture plates were then incubated at 37 °C for 2 h
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Published 11 Sep 2020

Naphthalene diimide bis-guanidinio-carbonyl-pyrrole as a pH-switchable threading DNA intercalator

  • Poulami Jana,
  • Filip Šupljika,
  • Carsten Schmuck and
  • Ivo Piantanida

Beilstein J. Org. Chem. 2020, 16, 2201–2211, doi:10.3762/bjoc.16.185

Graphical Abstract
  • chiral properties of the DNA or RNA helical structures [12][13], could also take advantage of induced CD spectrum (ICD) in the visible spectrum range of small achiral dyes, which they show only upon binding to DNA/RNA [14]. Moreover, with recent advances in fluorescence emission-based polarisation
  • free energy change. Moreover, at these conditions (n > 0.6) also strong new ICD bands are visible, pointing out that binding of surplus molecules of 4 is not random but well organised along the chiral double helix. Furthermore, such highly positively charged systems, which efficiently wrap around DNA
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Published 08 Sep 2020

Photosensitized direct C–H fluorination and trifluoromethylation in organic synthesis

  • Shahboz Yakubov and
  • Joshua P. Barham

Beilstein J. Org. Chem. 2020, 16, 2151–2192, doi:10.3762/bjoc.16.183

Graphical Abstract
  • reactions. Keywords: C–H activation; energy transfer; fluorination; photocatalysis; photosensitization; visible light; Review 1 Introduction 1.1 Importance of direct C–H fluorination/trifluoromethylation and photosensitization in organic synthesis 1.1.1 Importance of fluorine atoms in organic molecules
  • –H bond is matched to the HAT catalyst. For example, an electrophilic radical abstracts H atoms selectively from the most electron-rich or “hydridic” C–H bond [65]. 1.1.3 Importance of visible light and visible-light photosensitization in synthesis: Unlike many other traditional energy resources
  • processes [72][73][74][75][76][77]. However, the adoption of photochemistry into the toolbox of the synthetic organic chemist has been hindered by three phenomena: i) simple organic-molecule targets typically do not absorb (or have very small extinction coefficients for) visible light, which is among the
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Published 03 Sep 2020

Access to highly substituted oxazoles by the reaction of α-azidochalcone with potassium thiocyanate

  • Mysore Bhyrappa Harisha,
  • Pandi Dhanalakshmi,
  • Rajendran Suresh,
  • Raju Ranjith Kumar and
  • Shanmugam Muthusubramanian

Beilstein J. Org. Chem. 2020, 16, 2108–2118, doi:10.3762/bjoc.16.178

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  • synthesis of 2,4,5-trisubstituted oxazole from azirine. a) I2, PPh3; b) NaH, 1H-pyrazole; c) 2-bromoacetyl bromide, NaN3; d) heating; e) t-BuOK; f) Ph-CHO, visible light; g) KSCN, K2S2O8. Scope of the α-azidochalcones. The reactions were carried out at reflux temperature, using 1 (1 mmol), 2 (3 mmol
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Published 31 Aug 2020

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

Graphical Abstract
  • interacted with ds-DNA/RNA by threading intercalation. Different from a reference NDI dye with identical visible range absorbance (520–540 nm) and Stokes shifts in emission (+60 nm, quantum yield > 0.2), only these amino acid–NDI conjugates showed selective fluorimetric response for GC-DNA in respect to AT(U
  • colourless and non-fluorescent core-unsubstituted NDI with a new charge transfer band with an absorption maximum in the visible spectral range and a high fluorescence quantum yield (up to 58%) [23][25]. Further, the 2-amino substituent offers the possibility to connect various amino acid side chains, thus
  • ). The transition dipole moment associated with the HOMO-to-LUMO transition in the visible range (red arrow) and with the higher energy transition (blue arrow) are respectively shown superimposed on the minimised structure. Interactions of 3a,b, and 5 with ds-DNA/RNA For a study of interactions with
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Published 19 Aug 2020

Automated high-content imaging for cellular uptake, from the Schmuck cation to the latest cyclic oligochalcogenides

  • Rémi Martinent,
  • Javier López-Andarias,
  • Dimitri Moreau,
  • Yangyang Cheng,
  • Naomi Sakai and
  • Stefan Matile

Beilstein J. Org. Chem. 2020, 16, 2007–2016, doi:10.3762/bjoc.16.167

Graphical Abstract
  • unoptimized transfected cells is again best appreciated with the naked eye: Whereas the improvement of the automated selection from Figure 8a to Figure 8b is not visible on the first view, the improvement from Figure 11a to Figure 11d is massive, and Figure 11d starts to resemble more the quasiideal Figure 8b
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Published 14 Aug 2020

Metal-free synthesis of phosphinoylchroman-4-ones via a radical phosphinoylation–cyclization cascade mediated by K2S2O8

  • Qiang Liu,
  • Weibang Lu,
  • Guanqun Xie and
  • Xiaoxia Wang

Beilstein J. Org. Chem. 2020, 16, 1974–1982, doi:10.3762/bjoc.16.164

Graphical Abstract
  • appropriate radical precursors through visible-light promoted systems [15][16], transition-metal-catalyzed systems [17][18], or transition-metal-free systems [19][20], have emerged as a powerful strategy for the synthesis of diversely functionalized chroman-4-one derivatives. Organophosphorus compounds are
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Published 12 Aug 2020

Design, synthesis and application of carbazole macrocycles in anion sensors

  • Alo Rüütel,
  • Ville Yrjänä,
  • Sandip A. Kadam,
  • Indrek Saar,
  • Mihkel Ilisson,
  • Astrid Darnell,
  • Kristjan Haav,
  • Tõiv Haljasorg,
  • Lauri Toom,
  • Johan Bobacka and
  • Ivo Leito

Beilstein J. Org. Chem. 2020, 16, 1901–1914, doi:10.3762/bjoc.16.157

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  • measurements performed in DMSO, but their corresponding ISMs were more selective for benzoate (log Poct/wat = 1.88) [34] than for pivalate (log Poct/wat = 1.48) [35]. However, the influence of the ionophores’ affinities for carboxylates were clearly visible from the suppressed selectivity towards anions
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Published 04 Aug 2020

Synthesis and highly efficient light-induced rearrangements of diphenylmethylene(2-benzo[b]thienyl)fulgides and fulgimides

  • Vladimir P. Rybalkin,
  • Sofiya Yu. Zmeeva,
  • Lidiya L. Popova,
  • Valerii V. Tkachev,
  • Andrey N. Utenyshev,
  • Olga Yu. Karlutova,
  • Alexander D. Dubonosov,
  • Vladimir A. Bren,
  • Sergey M. Aldoshin and
  • Vladimir I. Minkin

Beilstein J. Org. Chem. 2020, 16, 1820–1829, doi:10.3762/bjoc.16.149

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  • as compared with 2-thienyl and 3-benzo[b]thienyl analogues. Exposure of the colored solutions to the visible light leads to the reverse conversion into the primary colorless hexatriene form. Here, we report the synthesis of 2-benzo[b]thienylfulgides with bulky diphenylmethylene substituents and the
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Published 22 Jul 2020

When metal-catalyzed C–H functionalization meets visible-light photocatalysis

  • Lucas Guillemard and
  • Joanna Wencel-Delord

Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147

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  • last decade particular attention has been focused on two modern fields, C–H bond activation, and visible-light-induced photocatalysis. Couplings through C–H bond activation involve the use of non-prefunctionalized substrates that are directly converted into more complex molecules, without the need of a
  • previous functionalization, thus considerably reduce waste generation and a number of synthetic steps. In parallel, transformations involving photoredox catalysis promote radical reactions in the absence of radical initiators. They are conducted under particularly mild conditions while using the visible
  • catalytic system is extremely appealing. In that perspective, the scope of this review aims to present innovative reactions combining C–H activation and visible-light induced photocatalysis. Keywords: C–H activation; C–H functionalization; dual catalysis; photoredox catalysis; radical chemistry
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Published 21 Jul 2020
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