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Search for "polarity" in Full Text gives 385 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Synthesis of novel multifunctional carbazole-based molecules and their thermal, electrochemical and optical properties

  • Nuray Altinolcek,
  • Ahmet Battal,
  • Mustafa Tavasli,
  • William J. Peveler,
  • Holly A. Yu and
  • Peter J. Skabara

Beilstein J. Org. Chem. 2020, 16, 1066–1074, doi:10.3762/bjoc.16.93

Graphical Abstract
  • microscopic solvent polarity [43][44], ET(30), increased from toluene to dimethyl sulfoxide (see also Table 3). A 141 nm red-shift was observed for 7a (from 465 nm to 606 nm) and an 86 nm red-shift was observed for 7b (from 423 nm to 509 nm). In comparison for 7b, this red-shift was more pronounced for 7a
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Published 19 May 2020

Suzuki–Miyaura cross coupling is not an informative reaction to demonstrate the performance of new solvents

  • James Sherwood

Beilstein J. Org. Chem. 2020, 16, 1001–1005, doi:10.3762/bjoc.16.89

Graphical Abstract
  • , equilibria, solubility, and ultimately product yield. If there is an observable change in reaction performance correlating to one or more solvent properties (often polarity), then it is possible to identify and implement an optimum solvent. Suzuki–Miyaura cross coupling is the premier method of palladium
  • catalysed carbon–carbon bond formation, making it an obvious case study to validate the performance of novel solvents [1][2][3][4][5][6][7]. The polarity of the solvent is known to determine the structure and activity of catalytic intermediates, the rate determining step, and stereochemistry (where
  • Supporting Information Supporting Information File 292: Synthetic procedures and calculation of reaction conversions and solvent polarity data. Funding This research was funded by the Bio-Based Industries Joint Undertaking (JU) under the European Union's Horizon 2020 research and innovation programme
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Published 13 May 2020

Aryl-substituted acridanes as hosts for TADF-based OLEDs

  • Naveen Masimukku,
  • Dalius Gudeika,
  • Oleksandr Bezvikonnyi,
  • Ihor Syvorotka,
  • Rasa Keruckiene,
  • Dmytro Volyniuk and
  • Juozas V. Grazulevicius

Beilstein J. Org. Chem. 2020, 16, 989–1000, doi:10.3762/bjoc.16.88

Graphical Abstract
  • were decreased by ca. 0.23 eV with respect to that of the other studied compounds due to the π-electronic coupling between the acridan and vinylphenyl moieties. The absorption spectra were not affected by the polarity of the solvent. Relatively structured PL spectra were obtained for solutions and
  • to polarity and aggregation effects. Despite these observations, emission of compounds 3–6 can mainly be assigned to π–π* transitions of local excited states. However, a slight contribution of charge transfer (CT) can be also recognized in the emission of the studied compounds 3–6 (Figure 3a). The
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Published 13 May 2020

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

Graphical Abstract
  • position of the absorption maximum and the quantum yields or the rate constants of the forward and reverse reaction also depend largely on the solvent polarity as well as on the position and the nature of the substituents either at the indoline or the chromene unit. Surprisingly, there are only a few
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Published 05 May 2020

Bipyrrole boomerangs via Pd-mediated tandem cyclization–oxygenation. Controlling reaction selectivity and electronic properties

  • Liliia Moshniaha,
  • Marika Żyła-Karwowska,
  • Joanna Cybińska,
  • Piotr J. Chmielewski,
  • Ludovic Favereau and
  • Marcin Stępień

Beilstein J. Org. Chem. 2020, 16, 895–903, doi:10.3762/bjoc.16.81

Graphical Abstract
  • fluorescence was only moderately quenched with increasing solvent polarity, and the quantum yields of 64 and 66% were recorded in acetonitrile for cNMI2H and cNMI3H, respectively. To explore the chiral properties of the helically distorted boomerangs, the separation of enantiomers was attempted for all of them
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Published 04 May 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

Graphical Abstract
  • state quencher, as well as by the lowered rate of the reaction in the presence of the triplet energy quencher 2,5-dimethylhexa-2,4-diene or pyridazines, additives with lower triplet state energies than 4-anisaldehyde (52). The fact that the solvent polarity did not affect the sensitivity of the process
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Published 23 Apr 2020

Efficient synthesis of piperazinyl amides of 18β-glycyrrhetinic acid

  • Dong Cai,
  • ZhiHua Zhang,
  • Yufan Meng,
  • KaiLi Zhu,
  • LiYi Chen,
  • ChangXiang Yu,
  • ChangWei Yu,
  • ZiYi Fu,
  • DianShen Yang and
  • YiXia Gong

Beilstein J. Org. Chem. 2020, 16, 798–808, doi:10.3762/bjoc.16.73

Graphical Abstract
  • modifications at the C3-OH group of 18β-glycyrrhetinic acid are identified to be relatively common and effective. The modification of the C3-OH group, altering the molecular polarity of 18β-glycyrrhetinic acid, may be an advantage in achieving better cytotoxicity or antiproliferative activity [8][9][10]. For
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Published 21 Apr 2020

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

Graphical Abstract
  • isolated as a purple solid in 60% yield. Subsequently, an in situ deprotection of the TIPS group was carried out with a solution of the triptycene-linked porphyrin 14. The polarity of the in situ deprotected product and TIPS protected starting material were very similar so TLC analysis was unable to
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Published 17 Apr 2020

Recent advances in Cu-catalyzed C(sp3)–Si and C(sp3)–B bond formation

  • Balaram S. Takale,
  • Ruchita R. Thakore,
  • Elham Etemadi-Davan and
  • Bruce H. Lipshutz

Beilstein J. Org. Chem. 2020, 16, 691–737, doi:10.3762/bjoc.16.67

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  • , Ohmiya and co-workers envisioned inverting the polarity of an aldehyde 81 via conversion into the corresponding α-alkoxyalkyl Cu(I) anion 78. Utilizing 78, which undergoes transmetallation to an initially formed Pd(II) intermediate (from oxidative addition) led to cross couplings affording benzhydryl
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Published 15 Apr 2020

Synthesis of organic liquid crystals containing selectively fluorinated cyclopropanes

  • Zeguo Fang,
  • Nawaf Al-Maharik,
  • Peer Kirsch,
  • Matthias Bremer,
  • Alexandra M. Z. Slawin and
  • David O’Hagan

Beilstein J. Org. Chem. 2020, 16, 674–680, doi:10.3762/bjoc.16.65

Graphical Abstract
  • vertical alignment (VA) LCD technology, liquid crystals with negative dielectric anisotropy are required [3]. Fluorine, as the most electronegative atom, forms stable bonds to carbon and can thus induce polarity. It is also attractive as a design feature due to the low polarizability of the C–F bond
  • dielectric anisotropic liquid crystals and the more rigid 1,1,6,7-tetrafluoroindane 4 led to an enhanced polarity and improved negative dielectric anisotropy character [8]. Other liquid crystals of this class are the recently reported fluorinated cyclohexane 5 and 1,1,2,2-tetrafluorocyclohexane 6 [9][10
  • should induce a large value for dielectric anisotropy. Compounds 8 and 9 were found to exhibit the expected negative Δε values, however, the overall polarity is low (8 = −0.5, 9 = −0.2). This is presumably due to the ability of the C–C bond attached to cyclopropane to rotate, and thus the compound will
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Published 14 Apr 2020

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

Graphical Abstract
  • formed and no desired acid. Therefore, we investigated the effect of polarity on the selectivity of the reaction by mixing acetonitrile with benzene (Table 3). Based on the result with pure acetonitrile as a solvent (Scheme 2 and Scheme 3), we expected a lower yield with higher concentrations of
  • unlikely to compete with ring closure to F for entropic reasons. All attempts to trap intermediate C using methanol or acetic acid as co-solvent (see Table 2) were unsuccessful and resulted in lower yields, especially in the case of methanol, likely due to the increased polarity of the reaction mixture
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Published 16 Mar 2020

Synthesis, liquid crystalline behaviour and structure–property relationships of 1,3-bis(5-substituted-1,3,4-oxadiazol-2-yl)benzenes

  • Afef Mabrouki,
  • Malek Fouzai,
  • Armand Soldera,
  • Abdelkader Kriaa and
  • Ahmed Hedhli

Beilstein J. Org. Chem. 2020, 16, 149–158, doi:10.3762/bjoc.16.17

Graphical Abstract
  • in organic chemistry [3]. The C–F bond is highly polarized and this polarity inhibits the lone pair donation from fluorine, making this element a weak coordinator. These properties are the basis for the unique properties of perfluoroalkylated compounds such as high viscosity, high density, high
  • chemical stability, low surface tension, low dielectric constants and low refractive index [4]. The usefulness of these properties makes fluorine an element of choice for the enhancement of promising properties, remained inaccessible otherwise. However, the combination of small size and high polarity of
  • relative to the other heteroatoms, suggesting that Oxd 1 is more polar than Oxd 2. Such a difference in polarity was corroborated by the direction of the dipole moment of RC (Table 5). Therefore, it is not surprising to find the molecular electron-deficient center so far from the axis of the molecule in
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Published 31 Jan 2020

Potent hemithioindigo-based antimitotics photocontrol the microtubule cytoskeleton in cellulo

  • Alexander Sailer,
  • Franziska Ermer,
  • Yvonne Kraus,
  • Rebekkah Bingham,
  • Ferdinand H. Lutter,
  • Julia Ahlfeld and
  • Oliver Thorn-Seshold

Beilstein J. Org. Chem. 2020, 16, 125–134, doi:10.3762/bjoc.16.14

Graphical Abstract
  • unit of indanocine (which is attached in ortho-position to the key south ring methoxy group) by a hydroxy function, giving HITub-1 (Figure 2). When HITub-1 later proved less bioactive than we had wished, we explored steric and polarity changes to this south ring hydroxy group by methylation (HITub-2
  • (in ortho-position to the key south ring methoxy group) has been replaced by a synthetically more accessible hydroxy group (delivered via demethylation of a trimethoxy precursor through BBr3). The hydroxy and amino groups have similar size and polarity, and can both act as H-bond donors or acceptors
  • absolute sense and the overall photoswitchability of potency comparing E- and Z-isomers. We began by methylating the south ring hydroxy group (HITub-2) to see how changes in size and polarity affect the bioactivity; surprisingly, the potency loss was not dramatic (indicating that this position is not a key
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Published 27 Jan 2020

Light-controllable dithienylethene-modified cyclic peptides: photoswitching the in vivo toxicity in zebrafish embryos

  • Sergii Afonin,
  • Oleg Babii,
  • Aline Reuter,
  • Volker Middel,
  • Masanari Takamiya,
  • Uwe Strähle,
  • Igor V. Komarov and
  • Anne S. Ulrich

Beilstein J. Org. Chem. 2020, 16, 39–49, doi:10.3762/bjoc.16.6

Graphical Abstract
  • derivatives of 2 [30]. The library contained 29 compounds grouped into several series: with natural amino acid mutations affecting the amphipathicity (series i), with point mutations that modulate polarity and conformational stability of the β-structural elements (series ii), with backbone N-alkylation and
  • between the empirical low-pH hydrophobicity of the peptides (as assessed from the retention times in reversed-phase HPLC) and toxicity against zebrafish embryos. Independent on the photoisomeric state and the type of toxicity assay, decreasing polarity of the peptides is accompanied by an increase in
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Published 07 Jan 2020

Facile regiodivergent synthesis of spiro pyrrole-substituted pseudothiohydantoins and thiohydantoins via reaction of [e]-fused 1H-pyrrole-2,3-diones with thiourea

  • Aleksandr I. Kobelev,
  • Nikita A. Tretyakov,
  • Ekaterina E. Stepanova,
  • Maksim V. Dmitriev,
  • Michael Rubin and
  • Andrey N. Maslivets

Beilstein J. Org. Chem. 2019, 15, 2864–2871, doi:10.3762/bjoc.15.280

Graphical Abstract
  • temperature of the reaction, but also on the polarity of the solvent. We found that optimal conditions for dominant formation of pseudothiohydantoin 3a were applied by stirring the reaction mixture at room temperature in ethyl or butyl acetate (Table 1, entries 2 and 6). For the development of a convenient
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Published 27 Nov 2019

An improved, scalable synthesis of Notum inhibitor LP-922056 using 1-chloro-1,2-benziodoxol-3-one as a superior electrophilic chlorinating agent

  • Nicky J. Willis,
  • Elliott D. Bayle,
  • George Papageorgiou,
  • David Steadman,
  • Benjamin N. Atkinson,
  • William Mahy and
  • Paul V. Fish

Beilstein J. Org. Chem. 2019, 15, 2790–2797, doi:10.3762/bjoc.15.271

Graphical Abstract
  • signalling pathway has been shown to regulate crucial aspects of cell fate determination, organogenesis, cell migration and polarity [1]. Importantly, compromised Wnt signalling has been implicated in the perturbation of synaptic integrity and function in Alzheimer’s disease (AD) [2]. Palmitoleoylation of
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Published 19 Nov 2019

A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions

  • Munmun Ghosh,
  • Valmik S. Shinde and
  • Magnus Rueping

Beilstein J. Org. Chem. 2019, 15, 2710–2746, doi:10.3762/bjoc.15.264

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  • chirally modified electrodes Electrochemical oxidation reactions have long served as substantial synthetic tool because of their ability to increase the functionality of organic molecules via reversing the polarity of electron-rich functional groups and thereby generating highly reactive intermediates
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Published 13 Nov 2019

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

Graphical Abstract
  • %. Furthermore, the N,N-dimethylaminophenyl-derivative 6c shows a pronounced emission solvatochromism (Figure 11, Table 9). While the polarity effect on the absorption maximum is only minor within a range of the longest wavelength maximum between 469 and 490 nm, the emission maximum is shifted bathochromically
  • with increasing solvent polarity in a range from green fluorescence (529 nm) in toluene to red fluorescence in DMSO (638 nm) (Figure 12). The observed positive emission solvatochromism is a consequence of a significant change in the dipole moment from the electronic ground to the vibrationally relaxed
  • quantum yield of 99% in solution and 11% in the solid state was achieved. Interestingly, the isomeric p-N,N-dimethylaminophenyl substitution in 6-position represents a system with aggregation-induced emission enhancement. These design principles of luminescent 1H-pyridines and α-pyrones as polarity
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Published 12 Nov 2019

Plasma membrane imaging with a fluorescent benzothiadiazole derivative

  • Pedro H. P. R. Carvalho,
  • Jose R. Correa,
  • Karen L. R. Paiva,
  • Daniel F. S. Machado,
  • Jackson D. Scholten and
  • Brenno A. D. Neto

Beilstein J. Org. Chem. 2019, 15, 2644–2654, doi:10.3762/bjoc.15.257

Graphical Abstract
  • 2,1,3-benzothiadiazole (BTD) core and its derivatives that are successfully applied in bioimaging experiments. (Left) UV–vis, (center) fluorescence emission and (right) solvatochromic effect (Stokes shift in wavenumbers versus solvent polarity in ETN) of the synthesized BTD-4APTEG (10 μM for all
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Published 06 Nov 2019

Arylisoquinoline-derived organoboron dyes with a triaryl skeleton show dual fluorescence

  • Vânia F. Pais,
  • Tristan Neumann,
  • Ignacio Vayá,
  • M. Consuelo Jiménez,
  • Abel Ros and
  • Uwe Pischel

Beilstein J. Org. Chem. 2019, 15, 2612–2622, doi:10.3762/bjoc.15.254

Graphical Abstract
  • emission maximum on changing to the polar solvent (Δλ = +7 nm). However, dye 19 features a solvatofluorochromic effect of Δλ = +41 nm under the same conditions. The dyes 16 and 18 show somewhat smaller bathochromic shifts on increasing the solvent polarity (Δλ = +20–22 nm). Regarding the fluorescence
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Published 04 Nov 2019

Probing of local polarity in poly(methyl methacrylate) with the charge transfer transition in Nile red

  • Aydan Yadigarli,
  • Qimeng Song,
  • Sergey I. Druzhinin and
  • Holger Schönherr

Beilstein J. Org. Chem. 2019, 15, 2552–2562, doi:10.3762/bjoc.15.248

Graphical Abstract
  • permittivity of polymers and its spatial distribution play a crucial role in the behavior of thin films, such as those used, e.g., as sensor coatings. In an attempt to develop a conclusive approach to determine these quantities, the polarity of the model polymer poly(methyl methacrylate) (PMMA) in 600 nm thin
  • films on a glass support was probed by the energy of the charge transfer transition in the oxazine dye Nile red (NR) at 25 °C. The absorption and fluorescence spectra of NR were observed to shift to the red with increasing solvent polarity, because of the intramolecular charge transfer character of the
  • NR molecules in the ground state and slow sub-glass transition (Tg) relaxations in PMMA. Keywords: charge transfer; dipole moment; fluorescence; inhomogeneous broadening; oxazine dye; polarity probe; polymer permittivity; Introduction The chain and segment mobility as well as the permittivity of
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Published 25 Oct 2019

Indium-mediated C-allylation of melibiose

  • Christian Denner,
  • Manuel Gintner,
  • Hanspeter Kählig and
  • Walther Schmid

Beilstein J. Org. Chem. 2019, 15, 2458–2464, doi:10.3762/bjoc.15.238

Graphical Abstract
  • Zemplén-deprotection and ozonolysis compound 4-anti was obtained. Purification at this stage utilizing conventional column chromatography was not feasible due to the high polarity of the obtained compound mixture, which contained pyranoid as well as furanoid isomers in their α,β-forms. Thus, per-O
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Published 16 Oct 2019

Ultrafast processes triggered by one- and two-photon excitation of a photochromic and luminescent hydrazone

  • Alessandro Iagatti,
  • Baihao Shao,
  • Alberto Credi,
  • Barbara Ventura,
  • Ivan Aprahamian and
  • Mariangela Di Donato

Beilstein J. Org. Chem. 2019, 15, 2438–2446, doi:10.3762/bjoc.15.236

Graphical Abstract
  • isomerization occurs on a fast <1 ps timescale in both toluene and acetonitrile, while the excited state lifetime of the Z-form depends on solvent polarity, suggesting a partial charge transfer nature of its low lying excited state. Time-resolved luminescence measurements evidence the presence of a main
  • solvent polarity. On the contrary, the excited state lifetime of the Z-isomer depends on the solvent properties and is especially short in MeOH, suggesting that the excited state of the molecule could have a partial charge transfer nature. Finally, transient absorption spectroscopy was employed as an
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Published 15 Oct 2019

Photochromic diarylethene ligands featuring 2-(imidazol-2-yl)pyridine coordination site and their iron(II) complexes

  • Andrey G. Lvov,
  • Max Mörtel,
  • Anton V. Yadykov,
  • Frank W. Heinemann,
  • Valerii Z. Shirinian and
  • Marat M. Khusniyarov

Beilstein J. Org. Chem. 2019, 15, 2428–2437, doi:10.3762/bjoc.15.235

Graphical Abstract
  • 504 nm in toluene, while a hypsochromic shift of 14 nm was observed in acetonitrile. This influence of solvent polarity was detected for all ligands [39]. The carbonyl group in the ethene bridge of 3 causes a significant bathochromic shift (68 nm in toluene) of the closed-ring isomer maximum in
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Published 15 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

Graphical Abstract
  • reversibly between two states comprising high amounts of (E)-11 and (Z)-11, respectively. The other part of the hypothesis was, that by this photoinduced isomerization a considerable drop of activity would occur due to the conformational change and the resulting changed geometry and polarity. However, this
  • after irradiation, we would have predicted, that at least the significant difference in polarity of (E)-11 and (Z)-11 should lead to marked differences of sirtuin engagement in vitro. However, recent results from a carefully designed azologization study performed by Rustler et al. led to comparable
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Published 16 Sep 2019
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