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Search for "complexation" in Full Text gives 391 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
MoO3 on zeolites MCM-22, MCM-56 and 2D-MFI as catalysts for 1-octene metathesis
Beilstein J. Org. Chem. 2018, 14, 2931–2939, doi:10.3762/bjoc.14.272
- OES (iCAP 7000, Thermo Scientific) was used. About 50 mg of the catalyst was digested in a mixture of HF, HCl, and HNO3 (1:2:2). The samples were placed in a Berghof microwave in a closed vessel at T = 140 °C for 35 min. Saturated solution of H3BO3 was then added for complexation of the excess of HF
Calixazulenes: azulene-based calixarene analogues – an overview and recent supramolecular complexation studies
Beilstein J. Org. Chem. 2018, 14, 2488–2494, doi:10.3762/bjoc.14.225
- -hydrocarbon calix[4]azulenes which have been synthesized in good yields by their method. This allowed studying their supramolecular properties. This report is of our latest work on the solution-state supramolecular complexation of one of these calix[4]azulenes, namely tetrakis(5,7-diphenyl)calix[4]azulene or
- solvents prevented a fuller examination of its potential supramolecular properties with fullerenes, a topic of particular interest to us [18]. Therefore, the solid state supramolecular complexation properties of 5 were experimentally studied using solid state NMR and XRD experiments, and also theoretically
- a chloroform solution-state complexation binding study with Lash and Colby’s calix[4]azulene 3 using a series of tetraalkylammonium halides and tetrafluoroborate salts [20]. This study was also supplemented by DFT studies to support the trends observed in the experimentally-derived binding constants
Synthesis of a water-soluble 2,2′-biphen[4]arene and its efficient complexation and sensitive fluorescence enhancement towards palmatine and berberine
Beilstein J. Org. Chem. 2018, 14, 2236–2241, doi:10.3762/bjoc.14.198
- , Shanghai 200444, P. R. China 10.3762/bjoc.14.198 Abstract A water-soluble 2,2′-biphen[4]arene (2,2’-CBP4) containing eight carboxylato moieties was synthesized and characterized. Its complexation behavior towards two alkaloids, palmatine (P) and berberine (B), was investigated by means of fluorescence and
- exhibited dramatic fluorescence enhancement of more than 600 times upon complexation with 2,2’-CBP4. Particularly, the fluorescence intensity is strong enough to be readily distinguished by the naked eye. Although the two guests have similar structures, the association constant of B with 2,2’-CBP4 (Ka
- as bioimaging and self-assembled drug delivery systems [33][34][35][36][37][38][39][40]. For example, our group demonstrated a direct host–guest complexation-based drug delivery system for oxaliplatin by carboxylatopillar[6]arene [36]. The encapsulation could not only improve the drug‘s stability in
Dynamic light scattering studies of the effects of salts on the diffusivity of cationic and anionic cavitands
Beilstein J. Org. Chem. 2018, 14, 2212–2219, doi:10.3762/bjoc.14.195
- regards to the former, we have shown how poorly solvated anions such as SCN− have an affinity for non-polar surfaces. Because of this, they can compete with the interactions between two non-polar surfaces in a host–guest complexation event and can induce an apparent weakening of the hydrophobic effect
- see no evidence of specific complexation here. More generally, despite the high charge density of 1, monovalent alkali metal ions cannot associate with it sufficiently to induce significant aggregation and a reverse Hofmeister effect. This was not, however, the case with divalent metal ions, which are
Tetrathiafulvalene – a redox-switchable building block to control motion in mechanically interlocked molecules
Beilstein J. Org. Chem. 2018, 14, 2163–2185, doi:10.3762/bjoc.14.190
- , extended π-surfaces [64] of TTF derivatives can have a stabilizing effect upon complexation. TTF (1) also forms inclusion complexes with neutral host molecules such as cyclodextrins (Figure 6). This complexation is mainly driven by the hydrophobic effect. α-Cyclodextrin (6) molecules encapsulate the
- TTF2+. This relatively straightforward concept of electrochemically triggered complexation and expulsion of the TTF molecule from different hosts forms the fundament for motion control in a variety of different MIMs. To illustrate how this redox-triggered complexation/decomplexation of pseudorotaxanes
Synthesis of new p-tert-butylcalix[4]arene-based polyammonium triazolyl amphiphiles and their binding with nucleoside phosphates
Beilstein J. Org. Chem. 2018, 14, 1980–1993, doi:10.3762/bjoc.14.173
- binding sites offering multipoint interactions with a substrate for the effective complexation [13]. Calix[4]arenes and their thia analogues have many advantages over other macrocycles that are frequently used as synthetic receptors, such as cyclodextrins [14], cucurbiturils [15], and pillararenes [16
- displacement from aggregates, decorated by positive charged thiacalixarene macrocycles. This approach was used for macrocycles 10a,b and 12a,b as well. Primarily, the fundamental regularities of dye complexation with 10a,b and 12a,b were studied in detail. The stoichiometry of the EY–calixarene complexes was
- vesicles upon binding to ADP can be a result of a complexation-induced distortion of the calixarene cavity provoking thus perturbation of the PDA backbone. Conclusion For the first time new calix[4]arenes adopting a cone stereoisomeric form bearing two or four azide groups directly located at the
Rational design of boron-dipyrromethene (BODIPY) reporter dyes for cucurbit[7]uril
Beilstein J. Org. Chem. 2018, 14, 1961–1971, doi:10.3762/bjoc.14.171
- investigate their complexation behaviour with CB7. The goal was to explore the suitability of this approach, the possibility to fine-tune binding constants with different anchor groups and to provide BODIPYs with different absorption and emission wavelengths as well as pKa values of the aniline substituent
- have been previously reported for some BODIPYs substituted with diamines in the aniline meso-position, and the decreased quantum yields were ascribed to the loose-bolt effect [41][54][55]. Complexation with CB7 Addition of excess CB7 to the BODIPY dyes at low pH values, in which the dyes are fully
- of the dyes increased upon addition of CB7 (Figure 3). This result is in accordance with the anticipated anchor group mechanism leading to a complexation-induced protonation of the dye (Figure 1). It also suggests that the BODIPY core is not encapsulated in the macrocyclic cavity and that
Synthesis and characterization of π–extended “earring” subporphyrins
Beilstein J. Org. Chem. 2018, 14, 1956–1960, doi:10.3762/bjoc.14.170
- detected in the very low field region. This indicates that the Pd is inserted in the cavity of 3 with the deprotonation of both N-H and meso-H. Meanwhile all signals belong to aromatic hydrogens shifted to a slightly higher field region after the complexation with Pd, which reveals that the insertion of
- ,β′-diiodosubporphyrin and diboryltripyrrane via a Suzuki–Miyaura coupling and following oxidation. This “earring” subporphyrin’s cavity allows for complexation of Pd atom to form the corresponding Pd complex. The 1H NMR spectra of the compounds reveal that the aromatic ring current does not extend
An amphiphilic pseudo[1]catenane: neutral guest-induced clouding point change
Beilstein J. Org. Chem. 2018, 14, 1937–1943, doi:10.3762/bjoc.14.167
- 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
- point was observed upon addition of 1,4-dicyanobutane to an aqueous solution of 1 (Figure 3b, indicating that the hydrophobic/hydrophilic ratio did not change much by the host–guest complexation between 1 and 1,4-dicyanobutane because 1,4-dicyanobutane was hidden inside the hydrophilic pillar[5]arene
- Information File, Figure S7, orange peak β) of 1,4-dicyanobutane. Chemical structures of (a) tri(ethylene oxide)-substituted pillar[n]arenes (1, n = 5; 2, n = 6), (b) pseudo[1]catenane 3, (c) de-threaded form of 3 by complexation with 1,4-dicyanobutane, and (d) model compound 4. 1H NMR spectra of (a) model
Diazirine-functionalized mannosides for photoaffinity labeling: trouble with FimH
Beilstein J. Org. Chem. 2018, 14, 1890–1900, doi:10.3762/bjoc.14.163
- comprising a lectin domain FimHL hosting the α-D-mannose-specific carbohydrate binding site and a pilin domain FimHP connecting the protein to the fimbrial shaft (Figure 2). Complexation of α-D-mannopyranoside ligands involves the entire mannoside glycon moiety whereas the aglycon portion sticks out of the
- sensitivity.) The bivalent ligand 5, on the other hand, seems to be sterically too demanding to allow good complexation with the carbohydrate binding site of FimH; mainly unspecific interactions with the surface of FimH were predicted in this case. Thus, synthesis of 5 was not undertaken. In contrast, the
- expected that it would be easier to photolabel peptides than FimH, after the failure with photolabeling of the model peptides we were hoping that labeling of FimH would be more successful, as our ligand was designed to bind to FimH. We reasoned that complexation of the photolabile mannoside 3 and FimH
Strong binding and fluorescence sensing of bisphosphonates by guanidinium-modified calix[5]arene
Beilstein J. Org. Chem. 2018, 14, 1840–1845, doi:10.3762/bjoc.14.157
- applications of them [25][26][27][28]. In this work, we report a fluorescent IDA approach for detecting BPs quantitatively in not only buffer solution but also artificial urine (Scheme 2). The rationale behind the IDA approach is the strong and selective complexation of BPs by guanidinium-modified calix[5
- , we employed fluorescein (Fl) as the reporter dye according to our previously published result [26]. Fl of high brightness is strongly encapsulated into the GC5A cavity (Ka = 5.0 × 106 M−1), accompanied with a drastic complexation-induced fluorescence quenching (Ifree/Ibound = 37). Taken together
- recovery, offers the opportunity for fluorescence “switch-on” sensing of BPs. In general, fluorescent IDA could be operated at low μM or even nM concentrations, which is desirable with respect to sensing sensitivity. We tested the host–guest complexation of GC5A with a total number of 9 BP drugs clinically
Host–guest complexes of conformationally flexible C-hexyl-2-bromoresorcinarene and aromatic N-oxides: solid-state, solution and computational studies
Beilstein J. Org. Chem. 2018, 14, 1723–1733, doi:10.3762/bjoc.14.146
- , aiding in the binding of polar guests such as N-oxides. Keywords: aromatic N-oxides; C–H···π Interactions; ditopic receptors; endo/exo complexation; host–guest chemistry; resorcinarenes; Introduction Resorcinarenes are macrocyclic compounds with a bowl-shaped cavity stabilised by circular
- encapsulation in the bowl-shaped upper rim (endo complexation) due to size complementarity between host cavity and guest shape, and are generally stabilised through multiple C–H···π interactions [26][27][28]. The cavity capacity to undergo induced conformational changes in response to the incorporation of
- , 1+BrC6 indicates either from combination of guest 1 and BrC6 or exo complex while 1@BrC6 denotes the endo complexation process. However, considering the host flexibility, ‘Δ’ (Table 1), which is the measure of difference between centroid-to-centroid distances of opposite host aromatic rings, guests
β-Hydroxy sulfides and their syntheses
Beilstein J. Org. Chem. 2018, 14, 1668–1692, doi:10.3762/bjoc.14.143
- sulfides. The reaction is proposed to proceed via formation of a copper complex by coordination of the copper to the sulfur and nitrogen atoms of the disulfide. The complexation is accompanied by an increase in the sulfur–sulfur bond length and assists the cleavage of this bond by the attacking nucleophile
- (II) iodide catalyst enables the use of both diaryl and dialkyl disulfides to provide the corresponding masked β-hydroxy sulfides. The proposed mechanism is depicted in Scheme 34 [69]. The reaction commences with the complexation/activation of the disulfide by the CuI catalyst. The nucleophilic alkene
A conformationally adaptive macrocycle: conformational complexity and host–guest chemistry of zorb[4]arene
Beilstein J. Org. Chem. 2018, 14, 1570–1577, doi:10.3762/bjoc.14.134
- types of organic cations hosted by TA4 (6+–10+) were tested with ZB4. Most of these guests can indeed be complexed. But there are some exceptions. Changing the core quaternary ammonium structure of 3+ completely shuts down the binding, because no obvious complexation-induced shifts were detected in the
- 1:1 mixture of ZB4 with 4+ or 5+ (Figures S1 and S2 in Supporting Information File 1). This indicates the importance of the core quaternary ammonium ions in the host−guest complexation. All other guests can be encapsulated in the cavity of ZB4, and significant chemical shifts on both the guests and
Hyper-reticulated calixarene polymers: a new example of entirely synthetic nanosponge materials
Beilstein J. Org. Chem. 2018, 14, 1498–1507, doi:10.3762/bjoc.14.127
- is confirmed to depend on a fine balance between different factors, namely Coulomb and π···π interactions, and steric effects. The importance of a compromise between these factors for the complexation into calixresorcinarenes has been recently assessed [42]. Moreover, in analogy with the bahavior
Recent applications of chiral calixarenes in asymmetric catalysis
Beilstein J. Org. Chem. 2018, 14, 1389–1412, doi:10.3762/bjoc.14.117
- these catalysts confirmed the necessary role of the calixarene skeleton in phase-transfer catalysis by preorganizing and orienting the amide groups properly to favor the complexation of Na+ cations. The effect of the ester group in the substrate and other parameters on the reaction were also
A three-armed cryptand with triazine and pyridine units: synthesis, structure and complexation with polycyclic aromatic compounds
Beilstein J. Org. Chem. 2018, 14, 1370–1377, doi:10.3762/bjoc.14.115
- libraries [2][25][34][35]) allowed accessing of more sophisticated architectures. In a previous work [32] we reported the formation of a host–guest complex between a cryptand having pyridine units in the bridges and 1,3,5-triphenylbenzene caps (1, Figure 1). Surprisingly, no complexation ability of cryptand
- [32] revealed its selective absorption ability for N2 and CO2 in the solid state. The low complexation ability of cryptand 1 in solution for aromatic guests is due to the unfavorable conformation of the 1,3,5-triphenylbenzene central units in which the peripheral aromatic rings are twisted with
- respect to the central benzene ring. In such twisted conformations there is a remarkable steric hindrance between the ortho hydrogen atoms of the central benzene ring and the ortho' hydrogen atoms of the peripheral aromatic units. These conformations are not favorable for a complexation of aromatic guests
A selective removal of the secondary hydroxy group from ortho-dithioacetal-substituted diarylmethanols
Beilstein J. Org. Chem. 2018, 14, 1229–1237, doi:10.3762/bjoc.14.105
- patent literature [44]. Benzophenones were also reduced to diarylmethanes using supercritical iPrOH at 350 °C [1], BF3·OEt2/H2O [33] and PhSiH3/MoCl2O2(H2O)2 [45]. The reductive deoxygenation reactions of diarylmethanols proceed via carbocationic species, which are formed by protonation or complexation
- diarylmethanes. Most probably, electron-donating groups on aryls facilitate both Zn complexation and stabilization of the intermediate carbocationic species formed. Conclusion In summary, a new example of the selective functional group transformation of diarylmethanols (Ar1Ar2CH(OH)) to diarylmethanes (Ar1Ar2CH2
An uracil-linked hydroxyflavone probe for the recognition of ATP
Beilstein J. Org. Chem. 2018, 14, 747–755, doi:10.3762/bjoc.14.63
- a uracil nucleobase to the known 4’-dimethylamino-hydroxyflavone fluorophore. Results: The complexation of this scaffold with ATP is already known. The complex is held together by stacking and electrostatic interactions. To achieve multi-point recognition, we designed the uracil-appended version of
- . Conclusions: The first, uracil-containing fluorescent ATP probe based on a hydroxyflavone fluorophore was synthesized and evaluated. A selective complexation with ATP was observed and a ratiometric response in the excitation spectrum. Keywords: ATP sensing; base-pairing; fluorescent probes; 3-hydroxyflavone
- interactions, which prompted us towards the synthesis of UHF by click chemistry. Fluorescence spectroscopy revealed a selective complexation with ATP with an association constant of around 2∙104 M−1 and a ratiometric response in the excitation spectrum. Results and Discussion Structure and calculations Based
Heterogeneous Pd catalysts as emulsifiers in Pickering emulsions for integrated multistep synthesis in flow chemistry
Beilstein J. Org. Chem. 2018, 14, 648–658, doi:10.3762/bjoc.14.52
- economical aspects [13]. One possibility to prepare heterogeneous transition metal catalysts is to immobilise palladium directly on a solid support such as activated carbon [14], zeolites [15], modified silica [16][17][18] or molecular sieves [19] to name but a few. Another option is the complexation of
An air-stable bisboron complex: a practical bidentate Lewis acid catalyst
Beilstein J. Org. Chem. 2018, 14, 618–625, doi:10.3762/bjoc.14.48
- -dimethyl-5,10-dihydroboranthrene (A in Scheme 1), developed in our group [13]. A complexation was confirmed by a high field shift of the aromatic protons compared with the non-coordinated catalyst A. As shown in Scheme 2, besides 1,2-diphenylhydrazine (1d), most of the Lewis bases including monodentate 1a
- optimized procedure, BBr3 was used to replace BCl3 and the dimerization reaction can be carried out in a normal Schlenk tube without any solvent. The methylation reagent, AlMe3 can be added in situ followed by the complexation with pyridazine. The one-pot procedure is also applicable to the synthesis of
- reactions were carried out and the results showed that the catalytic activity of the complex in IEDDA reactions depended on its performance in ligand exchange with the diazine substrates. Experimental Complexation of 5,10-dimethyl-5,10-dihydroboranthrene with Lewis bases: In the glovebox, 5,10-dimethyl-5,10
From dipivaloylketene to tetraoxaadamantanes
Beilstein J. Org. Chem. 2018, 14, 1–10, doi:10.3762/bjoc.14.1
- derivatives were prepared from 3 in order to examine their host–guest properties by ESI mass spectrometry and NMR spectroscopy. Some tetraoxaadamantanes were also examined in this way. For example, compound 30 (Figure 1) was found to have a particular affinity for complexation with choline [26][36], and the
The use of 4,4,4-trifluorothreonine to stabilize extended peptide structures and mimic β-strands
Beilstein J. Org. Chem. 2017, 13, 2842–2853, doi:10.3762/bjoc.13.276
- in good yield starting from the N-benzylation of L-proline in the presence of KOH, then activation of the carboxylic acid functionality of 10 using SOCl2 at low temperature, followed by condensation with 2-aminobenzophenone (Scheme 2). Complexation of 11 with nickel nitrate and glycine under basic
Binding abilities of polyaminocyclodextrins: polarimetric investigations and biological assays
Beilstein J. Org. Chem. 2017, 13, 2751–2763, doi:10.3762/bjoc.13.271
- between our materials and polyanions were investigated by studying the binding with sodium alginate. Finally, the complexation abilities of the same materials towards polynucleotides were assessed by studying their interaction with the model plasmid pUC19. Our results positively highlight the ability of
- synthesis of noble metal nanoparticles, and systems for the complexation and cell transfection of genetic material [17][18][19][20][21][22]. In particular, the complexation and transfection of polynucleotides also have been successfully accomplished by means of polycationic cyclodextrin or calixarene
- preliminary investigation of the polarimetric behaviour of free AmCDs was a prerequisite before addressing their complexation abilities by means of polarimetry. Thus, the relevant molar optical rotations Θ were measured at different pH values, in order to study the possible effect of the progressive
Binding abilities of a chiral calix[4]resorcinarene: a polarimetric investigation on a complex case of study
Beilstein J. Org. Chem. 2017, 13, 2698–2709, doi:10.3762/bjoc.13.268
- constant. As we will discuss in detail later, complexation of substrates 1–12 with CAP leads in several cases to the formation of 2:1 complexes, either alone or together with the corresponding 1:1 complexes (as accounted for by the analysis of the relevant Job plots). In these cases, Equation 1 cannot be
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