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Search for "aggregation" in Full Text gives 331 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Synthesis of dihydroquinazolines from 2-aminobenzylamine: N3-aryl derivatives with electron-withdrawing groups

  • Nadia Gruber,
  • Jimena E. Díaz and
  • Liliana R. Orelli

Beilstein J. Org. Chem. 2018, 14, 2510–2519, doi:10.3762/bjoc.14.227

Graphical Abstract
  • ][10][11], as tumor suppressors [12] and as neuroprotective agents has also been reported [13]. Some related 2-amino-DHQs were studied as blood platelet aggregation inhibitors [14], antihypertensive agents [15] or inhibitors of β-secretase, an important target for Alzheimer’s disease [16]. Additionally
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Published 26 Sep 2018

Dynamic light scattering studies of the effects of salts on the diffusivity of cationic and anionic cavitands

  • Anthony Wishard and
  • Bruce C. Gibb

Beilstein J. Org. Chem. 2018, 14, 2212–2219, doi:10.3762/bjoc.14.195

Graphical Abstract
  • account specific ion–ion interactions. To identify specific ion–ion interactions possibly contributing to the aggregation of proteins, we have used dynamic light scattering (DLS) to probe the aggregation of charged cavitands. DLS measurements of negatively charged 1 in the presence of a range of alkali
  • metal halides reveal no significant aggregation of host 1 as a function of the nature of the cation of the added salt. Only at high concentrations could trace amounts of aggregation be detected by 1H NMR spectroscopy. Contrarily, 1 was readily aggregated and precipitated by ZnCl2. In contrast, although
  • fluoride and chloride did not induce aggregation of positively charged host 2, this cavitand exhibited marked aggregation as a function of bromide and iodide concentration. Specifically, bromide induced small but significant amounts of dimerization, whilst iodide induced extreme aggregation. Moreover, in
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Published 23 Aug 2018

A self-assembled photoresponsive gel consisting of chiral nanofibers

  • Lei Zou,
  • Dan Han,
  • Zhiyi Yuan,
  • Dongdong Chang and
  • Xiang Ma

Beilstein J. Org. Chem. 2018, 14, 1994–2001, doi:10.3762/bjoc.14.174

Graphical Abstract
  • -isomers of azobenzene can stack with each other via π–π interactions. Further, the acylamino group of the glutamic acid moiety at the center of the molecule also promotes this aggregation through hydrogen bonding interactions. Finally, the chirality of glutamic acid may be magnified along with the
  • compound 3. These two azobenzene moieties within the molecule are close and the dimerization of the UPy moiety results in a more crowded structure. The circular dichroism (CD) spectrum was then measured to trace the different states of aggregation in solution of compound 3 in different solvents. Benzene
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Published 01 Aug 2018

Synthesis of new p-tert-butylcalix[4]arene-based polyammonium triazolyl amphiphiles and their binding with nucleoside phosphates

  • Vladimir A. Burilov,
  • Guzaliya A. Fatikhova,
  • Mariya N. Dokuchaeva,
  • Ramil I. Nugmanov,
  • Diana A. Mironova,
  • Pavel V. Dorovatovskii,
  • Victor N. Khrustalev,
  • Svetlana E. Solovieva and
  • Igor S. Antipin

Beilstein J. Org. Chem. 2018, 14, 1980–1993, doi:10.3762/bjoc.14.173

Graphical Abstract
  • performed for the first time. It was found that the synthesized macrocycles form stable aggregates with hydrodynamic diameters between 150–200 nm and electrokinetic potentials about +40 to +60 mV in water solutions. Critical aggregation concentration (CAC) values were measured using a micelle method with
  • proposed structure of 10b. It should be noted that there are unexpected interactions of tert-butyl protons 2 with methylene protons 6 as well as between aromatic protons 1 with hydroxy protons 4 that can be attributed to a strong aggregation of the amphiphilic molecules in the solution. Aggregation
  • properties of 10a,b and 12a,b in aqueous solutions and binding with nucleotides All synthesized derivatives 10a,b and 12a,b are well soluble in water/MES buffered solutions. We used the determination of the critical aggregation concentration (CAC) to elucidate the compounds’ aggregation behavior. This was
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Published 31 Jul 2018

Rational design of boron-dipyrromethene (BODIPY) reporter dyes for cucurbit[7]uril

  • Mohammad A. Alnajjar,
  • Jürgen Bartelmeß,
  • Robert Hein,
  • Pichandi Ashokkumar,
  • Mohamed Nilam,
  • Werner M. Nau,
  • Knut Rurack and
  • Andreas Hennig

Beilstein J. Org. Chem. 2018, 14, 1961–1971, doi:10.3762/bjoc.14.171

Graphical Abstract
  • aggregation was indicated by a downward curvature in the fluorescence intensity plots at dye concentrations above 60 to 120 nM. Further experiments were therefore conducted in 30% ACN. The absorption maximum was centred at ca. 500 nm for all aniline dyes (Figure 2a and Table 1) and the emission maximum was
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Published 30 Jul 2018

Artificial bioconjugates with naturally occurring linkages: the use of phosphodiester

  • Takao Shoji,
  • Hiroki Fukutomi,
  • Yohei Okada and
  • Kazuhiro Chiba

Beilstein J. Org. Chem. 2018, 14, 1946–1955, doi:10.3762/bjoc.14.169

Graphical Abstract
  • specific sequences can cause aggregation and thus severely inhibit further reactions; however, our support could possibly address such technical problems. Gratifyingly, although further optimization of the reaction conditions is needed for the deprotection reactions (see Schemes S5 and S6 in Supporting
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Published 27 Jul 2018

An amphiphilic pseudo[1]catenane: neutral guest-induced clouding point change

  • Tomoki Ogoshi,
  • Tomohiro Akutsu and
  • Tada-aki Yamagishi

Beilstein J. Org. Chem. 2018, 14, 1937–1943, doi:10.3762/bjoc.14.167

Graphical Abstract
  • aggregation of the hydrophobic alkyl chain rings, which induced insolubilization of the bicyclic compound in aqueous media at 20 °C and a decrease in its clouding point. Keywords: amphiphilic molecules; host–guest complexes; lower critical solution temperature; pillar[n]arenes; pseudo[1]catenane
  • temperature, but de-solvation occurs upon heating, which triggers aggregation of the hydrophobic pillar[n]arene cores. The amphiphilic pillar[n]arenes can capture guest molecules with encapsulation of an ionic guest molecule resulting in a change of the hydrophobic/hydrophilic ratio, and consequently a change
  • 1,4-dicyanobutane, the clouding points gradually decreased from 24 °C to 12 °C (Figure 3a). Formation of the de-threaded form by complexation between 3 and 1,4-dicyanobutane induced aggregation of the alkyl chain ring on the outside of the cavity. However, only a very minor change in the clouding
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Published 26 Jul 2018

Synthesis of 9-arylalkynyl- and 9-aryl-substituted benzo[b]quinolizinium derivatives by Palladium-mediated cross-coupling reactions

  • Siva Sankar Murthy Bandaru,
  • Darinka Dzubiel,
  • Heiko Ihmels,
  • Mohebodin Karbasiyoun,
  • Mohamed M. A. Mahmoud and
  • Carola Schulzke

Beilstein J. Org. Chem. 2018, 14, 1871–1884, doi:10.3762/bjoc.14.161

Graphical Abstract
  • = 418 nm) that is similar to that of the parent compound 2a (Figure 3C). It should be noted that the benzo[b]quinolizinium derivatives 2a–d have lower absorbance and significantly broadened spectra in less polar solvents, presumably due to their low solubility and the resulting aggregation in these
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Published 23 Jul 2018

Design, synthesis and structure of novel G-2 melamine-based dendrimers incorporating 4-(n-octyloxy)aniline as a peripheral unit

  • Cristina Morar,
  • Pedro Lameiras,
  • Attila Bende,
  • Gabriel Katona,
  • Emese Gál and
  • Mircea Darabantu

Beilstein J. Org. Chem. 2018, 14, 1704–1722, doi:10.3762/bjoc.14.145

Graphical Abstract
  • ) adjacent >Nsp2–H···π-enriched (hetero)cycles. Surprisingly, single trimer 4 ([D-N

    N]3C3N3, Figure 1), containing s-triazine as linearly linked core, gave no distinct spherical aggregation (Supporting Information File 1, p. S41, Figure S56). In contrast, by replacing the P-1 piperazine linker in 4 with a

  • 4-oxyphenylamino unit, the resulting dendrimer 6 ([D3]B, Figure 1), still encompassing s-triazine as core but propeller angularly coupled, evidenced a total opposite behaviour, i.e., aggregation under the form of nanospheres with the highest (732 nm) D value. Trimers of D-N

    NH angularly-propeller

  • . The structural variety of the covalent dendritic elaboration around the m-trivalent cores (1,4-phenylene over piperazin-1,4-diyl adjacent linkers, propeller over asymmetric rotamerism of the angular over linear connectivity) modulated the degree of nano-aggregation. Experimental General All reagents
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Published 09 Jul 2018

The phenyl vinyl ether–methanol complex: a model system for quantum chemistry benchmarking

  • Dominic Bernhard,
  • Fabian Dietrich,
  • Mariyam Fatima,
  • Cristóbal Pérez,
  • Hannes C. Gottschalk,
  • Axel Wuttke,
  • Ricardo A. Mata,
  • Martin A. Suhm,
  • Melanie Schnell and
  • Markus Gerhards

Beilstein J. Org. Chem. 2018, 14, 1642–1654, doi:10.3762/bjoc.14.140

Graphical Abstract
  • hydrogen bonds; Introduction The balance of different noncovalent interactions is crucial for chemical and biochemical processes as it controls molecular recognition and aggregation [1][2][3][4][5][6]. In order to gain a deeper understanding of these processes, knowledge on exact structural arrangements
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Published 02 Jul 2018

Recent advances in phosphorescent platinum complexes for organic light-emitting diodes

  • Cristina Cebrián and
  • Matteo Mauro

Beilstein J. Org. Chem. 2018, 14, 1459–1481, doi:10.3762/bjoc.14.124

Graphical Abstract
  • aggregation was observed at dopant concentrations above 12 wt %. Although (hetero-)metallic clusters are beyond the scope of this review, it is worth to mention some recent reports from Chen and co-workers on trimetallic systems based on PtAu2 [21][22] and PtAg2 [23][24] core. Motivated by very high PLQYs in
  • illustrated in a following work by the group of Chi [14]. Exploiting the strong tendency to form ordered structures, a new series of platinum(II) bearing fluorinated 2-pyrazinylpyrazoles was developed, namely complexes 16–18 in Figure 8. Upon aggregation, very efficient NIR emission arising from a 3MMLCT
  • and high thermal stability. Unfortunately, going from dilute solution to neat solid-state samples, PLQY values dramatically dropped to values as low as 0.10–0.02 that might point to strong intermolecular interaction and TTA phenomena. The tendency toward aggregation for complex 44 and 46 in condensed
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Published 18 Jun 2018

Design and biological characterization of novel cell-penetrating peptides preferentially targeting cell nuclei and subnuclear regions

  • Anja Gronewold,
  • Mareike Horn and
  • Ines Neundorf

Beilstein J. Org. Chem. 2018, 14, 1378–1388, doi:10.3762/bjoc.14.116

Graphical Abstract
  • structures as a result of peptide/lipid aggregation [34]. However, since only the fluorescence of the fluorophore can be detected, it can of course not be ruled out that degradation of the peptides has been already started. Quantifying the amount of the novel peptides after 120 min demonstrated further that
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Published 07 Jun 2018

An overview of recent advances in duplex DNA recognition by small molecules

  • Sayantan Bhaduri,
  • Nihar Ranjan and
  • Dev P. Arya

Beilstein J. Org. Chem. 2018, 14, 1051–1086, doi:10.3762/bjoc.14.93

Graphical Abstract
  • addition, replaced the monocationic Dp group [3-(dimethylamino)propylamine] in conjugate 20 with a dicationic Ta group (3,3'-diamino-N-methyldipropylamine) in conjugate 21 to minimize the frequently observed polyamide aggregation. This subtle modification retains the polyamide-DNA binding mode and affinity
  • by reducing aggregation and also helps to conduct a detailed thermodynamic study for the 8-ring HP polyamides for the very first time. Recently, Hartley et al. designed and synthesized a hybrid fluorescent HP polyamide conjugate 22 (Figure 6) by attaching the A·T recognizing fluorophore, p
  • Hoechst 33258. These conjugates are fluorescent dimeric bisbenzimidazoles [(DB)n and (DBP)n] tethered by oligomethylene linkers of varied lengths with or without a central 1,4-piperazine residue [117]. The low solubility of (DB)n in aqueous solution due to aggregation has forced the authors to introduce a
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Published 16 May 2018

Phosphodiester models for cleavage of nucleic acids

  • Satu Mikkola,
  • Tuomas Lönnberg and
  • Harri Lönnberg

Beilstein J. Org. Chem. 2018, 14, 803–837, doi:10.3762/bjoc.14.68

Graphical Abstract
  • at [5] = 1 mmol L−1 and 37 °C. Aggregation of 5 with RNA prevented detailed mechanistic studies. The catalyst was, however, active even in the non-aggregated state, though possibly somewhat less efficient. The pKa value of the 2-aminobenzimidazolium ion is about 7, being exceptionally low for a
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Published 10 Apr 2018

Synthesis and in vitro biochemical evaluation of oxime bond-linked daunorubicin–GnRH-III conjugates developed for targeted drug delivery

  • Sabine Schuster,
  • Beáta Biri-Kovács,
  • Bálint Szeder,
  • Viktor Farkas,
  • László Buday,
  • Zsuzsanna Szabó,
  • Gábor Halmos and
  • Gábor Mező

Beilstein J. Org. Chem. 2018, 14, 756–771, doi:10.3762/bjoc.14.64

Graphical Abstract
  • aggregation could be observed in HPLC or MS measurements, we assume that the presence of the β-hairpin structure is a feasible conception in these cases. Stability/degradation of the GnRH-III bioconjugates Drug delivery systems (DDS) are promising therapeutics for tumor therapy providing a selective
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Published 04 Apr 2018

Nanoreactors for green catalysis

  • M. Teresa De Martino,
  • Loai K. E. A. Abdelmohsen,
  • Floris P. J. T. Rutjes and
  • Jan C. M. van Hest

Beilstein J. Org. Chem. 2018, 14, 716–733, doi:10.3762/bjoc.14.61

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  • imparted by the PS layer endowed Au@PEG-b-PS with good reusability in catalysis without the loss of catalytic activity, and prevented from electrolyte-induced aggregation, making the system very attractive as nanoreactor. Following on the previous work, He et al. synthesized cross-linked nanogels that were
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Published 29 Mar 2018

D–A–D-type orange-light emitting thermally activated delayed fluorescence (TADF) materials based on a fluorenone unit: simulation, photoluminescence and electroluminescence studies

  • Lin Gan,
  • Xianglong Li,
  • Xinyi Cai,
  • Kunkun Liu,
  • Wei Li and
  • Shi-Jian Su

Beilstein J. Org. Chem. 2018, 14, 672–681, doi:10.3762/bjoc.14.55

Graphical Abstract
  • %, respectively). As shown in Supporting Information File 1, both PL spectra of the doped films of 1:CBP and 2:CBP show red-shift from their PL spectra in n-hexane, which could be considered as the influence from aggregation. As mentioned above, 1 and 2 show nearly the same PL spectra in their dilute toluene
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Published 22 Mar 2018

Enhanced quantum yields by sterically demanding aryl-substituted β-diketonate ancillary ligands

  • Rebecca Pittkowski and
  • Thomas Strassner

Beilstein J. Org. Chem. 2018, 14, 664–671, doi:10.3762/bjoc.14.54

Graphical Abstract
  • of duryl complex 3 mostly remains structurally unresolved. For both complexes, very high quantum yields of 82% (2) and 73% (3) at ambient temperatures as well as short decay times around 3 μs (Table 1) were measured. The complexes show no aggregation behavior at higher concentrations (10 wt % in PMMA
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Published 21 Mar 2018

Heterogeneous Pd catalysts as emulsifiers in Pickering emulsions for integrated multistep synthesis in flow chemistry

  • Katharina Hiebler,
  • Georg J. Lichtenegger,
  • Manuel C. Maier,
  • Eun Sung Park,
  • Renie Gonzales-Groom,
  • Bernard P. Binks and
  • Heidrun Gruber-Woelfler

Beilstein J. Org. Chem. 2018, 14, 648–658, doi:10.3762/bjoc.14.52

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  • particle concentrations may be due to particle aggregation in water prior to emulsification. Such large particle aggregates of high density would be weakly retained at the oil–water interfaces offering little protection to the coalescence between drops. However, a more detailed look at the particle size in
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Published 19 Mar 2018

Carbohydrate inhibitors of cholera toxin

  • Vajinder Kumar and
  • W. Bruce Turnbull

Beilstein J. Org. Chem. 2018, 14, 484–498, doi:10.3762/bjoc.14.34

Graphical Abstract
  • favoured an aggregation mechanism for inhibition [55] whereas matching the valency has previously been assumed to lead to the formation of 1:1 complexes [59][60][61][62][63][64]. They found that the potency exhibited by compound 33 in the usual enzyme-linked lectin assay (IC50 = 260 ± 20 pM) was slightly
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Published 21 Feb 2018

Novel amide-functionalized chloramphenicol base bifunctional organocatalysts for enantioselective alcoholysis of meso-cyclic anhydrides

  • Lingjun Xu,
  • Shuwen Han,
  • Linjie Yan,
  • Haifeng Wang,
  • Haihui Peng and
  • Fener Chen

Beilstein J. Org. Chem. 2018, 14, 309–317, doi:10.3762/bjoc.14.19

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  • chloramphenicol-derived bifunctional amide organocatalysts and their application for enantioselective alcoholysis of meso-cyclic anhydrides. In the precedented urea- or thiourea-based organocatalytic methanolysis of anhydrides, one big problem is the homo-aggregation of the catalysts via hydrogen bonding, which
  • decreased the reactivity and enantioselectivity and required diluted concentrations with low temperatures [47]. With the new chloramphenicol base amide organocatalysts we envisioned that the presence of a bulky oxygen group could avoid the intermolecular aggregation of the catalyst, while keeping the
  • , entries 20–23). These results implicated that there is no significant aggregation of catalysts in this system. This bifunctional Brønsted acid/base catalyst 7i proved to be highly active toward asymmetric methanolysis of various meso-cyclic anhydrides. As shown in Table 2, various cyclic anhydrides were
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Published 31 Jan 2018

Recent advances on organic blue thermally activated delayed fluorescence (TADF) emitters for organic light-emitting diodes (OLEDs)

  • Thanh-Tuân Bui,
  • Fabrice Goubard,
  • Malika Ibrahim-Ouali,
  • Didier Gigmes and
  • Frédéric Dumur

Beilstein J. Org. Chem. 2018, 14, 282–308, doi:10.3762/bjoc.14.18

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  • the strong interaction and aggregation between CN-P1 molecules at high doping concentration in the emitting layer. Authors obtained EL spectra red-shifting from sky-blue (λmax = 475 nm, CIE = (0.18, 0.26)) to greenish-blue (λmax = 510 nm, CIE = (0.24, 0.40)) emissions by varying the doping
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Published 30 Jan 2018

Fluorogenic PNA probes

  • Tirayut Vilaivan

Beilstein J. Org. Chem. 2018, 14, 253–281, doi:10.3762/bjoc.14.17

Graphical Abstract
  • ] improved the performance of the system by reducing the nonspecific aggregation of the hydrophobic CPP and by reducing its non-specific binding with ssDNA. Up to a 10-fold improvement in the detection sensitivity in the presence of sodium dodecylsulfate (SDS) was reported [121]. Detection of dsDNA targets
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Published 29 Jan 2018

5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines

  • Ranjana Aggarwal and
  • Suresh Kumar

Beilstein J. Org. Chem. 2018, 14, 203–242, doi:10.3762/bjoc.14.15

Graphical Abstract
  • Pyrazolo[3,4-b]pyrazines have received great attention because of their interesting biological activities such as inhibition of protein kinases [137], blood platelet aggregation [138], bone metabolism improvers [139] as well as antifungal [140], antibacterial [141], antiparasitic [142] and antiviral [143
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Published 25 Jan 2018

Polarization spectroscopy methods in the determination of interactions of small molecules with nucleic acids – tutorial

  • Tamara Šmidlehner,
  • Ivo Piantanida and
  • Gennaro Pescitelli

Beilstein J. Org. Chem. 2018, 14, 84–105, doi:10.3762/bjoc.14.5

Graphical Abstract
  • ligand aggregates binding to polynucleotides (Figure 2). Many naturally occurring small molecules owe different biological activities due to aggregation, for instance, the close analogs netropsin (the single molecule in the DNA minor groove) and distamycin (the dimer in DNA minor groove) [13]. In
  • foreseen for further experiments. If the light absorbance is proportional to concentration, i.e., the Beer–Lambert law is fully respected, there is no intramolecular aggregation of the ligand. However, a non-linear response, usually hypochromic (i.e., a negative deviation from the Beer–Lambert law
  • UV–vis spectrum and if applicable, ECD spectrum at various temperatures, can give useful information about intra- or intermolecular interactions of a ligand. However, an ECD spectrum depends on the temperature in several ways other than affecting aggregation, for example by changing conformational
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Published 08 Jan 2018
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