Supramolecular polymerization of sulfated dendritic peptide amphiphiles into multivalent L-selectin binders

• David Straßburger,
• Svenja Herziger,
• Katharina Huth,
• Moritz Urschbach,
• Rainer Haag and
• Pol Besenius

Beilstein J. Org. Chem. 2021, 17, 97–104, doi:10.3762/bjoc.17.10

• Research Center of Electron Microscopy, Freie Universität Berlin, Fabeckstr. 34a, 14195 Berlin 10.3762/bjoc.17.10 Abstract The synthesis of a sulfate-modified dendritic peptide amphiphile and its self-assembly into one-dimensional rod-like architectures in aqueous medium is reported. The influence of the

• ionic strength on the supramolecular polymerization was probed via circular dichroism spectroscopy and cryogenic transmission electron microscopy. Physiological salt concentrations efficiently screen the charges of the dendritic building block equipped with eight sulfate groups and trigger the formation

• we have assigned this characteristic CD band to a β-sheet-dominated short-range ordering of oligopeptide monomers, which is stable over a wide concentration range [30][39][40]. The application of transmission electron microscopy (TEM) gave further insight into the morphology of the assemblies induced

Control over size, shape, and photonics of self-assembled organic nanocrystals

• Chen Shahar,
• Yaron Tidhar,
• Yunmin Jung,
• Haim Weissman,
• Sidney R. Cohen,
• Ronit Bitton,
• Iddo Pinkas,
• Gilad Haran and
• Boris Rybtchinski

Beilstein J. Org. Chem. 2021, 17, 42–51, doi:10.3762/bjoc.17.5

• medium. The ONCs have a thin rectangular shape, with an aspect ratio that is controlled by the content of the organic cosolvent (THF). The nanocrystals were characterized in solution by cryogenic transmission electron microscopy (cryo-TEM) and small-angle X-ray scattering. The ONCs retain their structure

• inversion, red shift, and significant broadening in comparison to the molecularly dissolved system (Figure 1B). This is a typical spectral signature of ordered PDI systems and crystals [38][43][44][45][46][47] having a face-to-face orientation of the π-systems. Cryogenic transmission electron microscopy

• ) and Origin 7.5 (OriginLab) softwares. Chemical structure of compound 1 and UV–vis spectra in an aggregating aqueous medium and in the disaggregating solvent THF. Transmission electron microscopy (TEM) images (left, zoomed-out and zoomed-in; 1 × 10−4 M solutions of 1 deposited on TEM grids) and crystal

Molecular basis for protein–protein interactions

• Brandon Charles Seychell and
• Tobias Beck

Beilstein J. Org. Chem. 2021, 17, 1–10, doi:10.3762/bjoc.17.1

• [15]. In the past few years, advances in the cryo-EM technology attracted the interest of more and more structural biologists. In fact, the number of cryo-EM structures has steadily been increasing over the recent years, with over 12,500 electron density maps being deposited in the Electron Microscopy

• methods. These methods are summarised in Figure 1. Atomic resolution methods focus on the structure determination of protein complexes and elucidating the PPIs at a near-atomic resolution. Such methods include X-ray crystallography [12], nuclear magnetic resonance (NMR) [13], and cryogenic electron

• microscopy (cryo-EM) [14]. Traditionally, X-ray crystallography was the preferred method to solve the protein structure and determine protein–protein interfaces. However, protein crystallography has the limitation that some protein assemblies have a low diffraction quality and are difficult to crystallise

Ultrasound-assisted Strecker synthesis of novel 2-(hetero)aryl-2-(arylamino)acetonitrile derivatives

• Emese Gal,
• Luiza Gaina,
• Hermina Petkes,
• Alexandra Pop,
• Castelia Cristea,
• Gabriel Barta,
• Dan Cristian Vodnar and
• Luminiţa Silaghi-Dumitrescu

Beilstein J. Org. Chem. 2020, 16, 2929–2936, doi:10.3762/bjoc.16.242

• precipitated from the reaction mixture in crystalline form as depicted by scanning electron microscopy (SEM) analysis. The single crystal X-ray diffraction analysis disclosed the arrangement of the α-(arylamino)acetonitrile molecules in the aggregated crystalline state as a racemic mixture. The mutagenic

• angle of 64.5°. The intermolecular distances are situated in the range 2.3–2.6 Å disclosing the lack of intermolecular interactions in the crystal structure. Scanning electron microscopy (SEM) analysis Besides process intensification leading to a shorter reaction time, another advantage of the

A novel and robust heterogeneous Cu catalyst using modified lignosulfonate as support for the synthesis of nitrogen-containing heterocycles

• Bingbing Lai,
• Meng Ye,
• Ping Liu,
• Minghao Li,
• Rongxian Bai and
• Yanlong Gu

Beilstein J. Org. Chem. 2020, 16, 2888–2902, doi:10.3762/bjoc.16.238

• results indicated that all prepared materials could remain stable in the system when used to catalyze organic reactions. FSEM (field emission scanning electron microscopy) and FTEM (field emission transmission electron microscopy) were used to observe the surface morphologies of different catalysts, and

• ) conditions. ICP-MS data were recorded on ELAN DRC-e device. The morphologies of samples were observed by scanning electron microscopy (SEM, Sirion 200, Holland) equipped with an energy dispersive X-ray (EDX) spectroscopy and transmission electron microscopy (TEM, Talos F200X), respectively. 1H and 13C NMR

Dirhamnolipid ester – formation of reverse wormlike micelles in a binary (primerless) system

• David Liese,
• Hans Henning Wenk,
• Xin Lu,
• Jochen Kleinen and
• Gebhard Haberhauer

Beilstein J. Org. Chem. 2020, 16, 2820–2830, doi:10.3762/bjoc.16.232

• supported by rheological measurements [42] and finally validated by transmission electron microscopy at cryogenic temperature (cryo-TEM) [43]. Temperature-dependent rheology Next, the temperature dependence of the rheology for the RWLM will be described. Oscillatory-shear experiments were performed for the

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

• derivatives in aqueous buffer (5 mM tris-HCl, 10 mM NaCl, water/DMSO 99.5:0.5, pH 7.4) were investigated using a combination of absorption and emission spectral studies, dynamic light scattering (DLS) and field emission scanning electron microscopy (FESEM). In a “good solvent” such as DMSO, in which all

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

• )–dipicolylamine complexes beyond 25% had a negative impact on the limit of detection and the optical response. Transmission electron microscopy provided evidence that the changes of the nanoparticle properties observed in the presence of the phosphates were due to a nanoparticle crosslinking, consistent with the

• signals of the immobilized ligand molecules but no sharp signals, showing that the nanoparticles were not contaminated with unbound ligands or residual citrate. According to transmission electron microscopy (TEM), NPrac-1 had an average diameter of 9.1 ± 2.4 nm and a maximum of the SPR band in the UV–vis

Particle size effect in the mechanically assisted synthesis of β-cyclodextrin mesitylene sulfonate

• Stéphane Menuel,
• Sébastien Saitzek,
• Eric Monflier and
• Frédéric Hapiot

Beilstein J. Org. Chem. 2020, 16, 2598–2606, doi:10.3762/bjoc.16.211

• highlighting the advantages of the mechanically assisted synthesis. Results and Discussion Analysis of ground CDs Scanning electron microscopy (SEM) SEM enables particle size evolution upon grinding to be monitored. The SEM images in Figure 1 show the surface topography changes of polycrystalline β-CD for six

• speed of 0.4°/min) using the Bragg–Brentano configuration. Scanning electron microscopy Scanning electron microscopy (SEM) images were recorded on a SEM JEOL JSM-7800F LV instrument at 3.0 kV. The powder was deposited on a carbon-coated copper grid. The particle size distributions were determined from

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

• hydrophobic effect and to host–guest π–π interactions. Hydrophobic surface simulations showed that TBTQ-(OG)6 and C60 forms an amphiphilic supramolecular host–guest complex, which further assembles to microspheres with diameters of 0.3–3.5 μm, as determined by scanning electron microscopy. Keywords

• of this host with C60 and C70-fullerene was investigated in co-organic solvents and in aqueous solution. The hydrophobic surface simulation of this host indicated the formation of a supra-amphiphilic system, which, as shown by scanning electron microscopy, further self-assembles into microspheres in

• -(OG)6, and TBTQ-(OG)6 C60 were investigated by scanning electron microscopy (SEM). As shown in Figure 7a and 7b, respectively, the SEM image of C60-fullerene displays cylindrical nanotubes and that of TBTQ-(OG)6 does not indicate any definite shape. However, well-dispersed microspheres with diameters

Leveraging glycomics data in glycoprotein 3D structure validation with Privateer

• Haroldas Bagdonas,
• Daniel Ungar and
• Jon Agirre

Beilstein J. Org. Chem. 2020, 16, 2523–2533, doi:10.3762/bjoc.16.204

• complexity of glycans in glycoproteins have been, and currently remain, significant challenges in structural biology. These aspects present unique problems to the two most prolific techniques: X-ray crystallography and cryo-electron microscopy. At the same time, advances in mass spectrometry have made it

Palladium nanoparticles supported on chitin-based nanomaterials as heterogeneous catalysts for the Heck coupling reaction

• Tony Jin,
• Malickah Hicks,
• Davis Kurdyla,
• Sabahudin Hrapovic,
• Edmond Lam and
• Audrey Moores

Beilstein J. Org. Chem. 2020, 16, 2477–2483, doi:10.3762/bjoc.16.201

• Information File 1) [16]. ChNCs were treated with ammonium persulfate (APS) for 16 h to form disperse ChNCs after washing. ChsNCs were made by deacetylating ChNCs in the presence of concentrated NaOH as well as a small amount of NaBH4 (Scheme 1). As seen through transmission electron microscopy (TEM) in

• Information File 498: Experimental part. Acknowledgements We thank the Facility for Electron Microscopy Research of McGill University for help in data collection. We thank the MC2 facility at McGill University for help in acquiring the FTIR spectra. Specifically, we thank Dr. Hatem Titi from the MC2 facility

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

• by means of UV–vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), and transmission electron microscopy (TEM) analysis (see Supporting Information File 1). Concerning the chemical structure of the conjugate, the data reported in the literature were

• ° scattering angle with temperature controlled at 25 °C in 1 mL polystyrene cuvettes. Dex-1b was characterized in terms of size. Short time measurements were carried out for a total of 15 min, with three consecutive measurements for each sample. Transmission electron microscopy images were aquired by a JEOL

Natural dolomitic limestone-catalyzed synthesis of benzimidazoles, dihydropyrimidinones, and highly substituted pyridines under ultrasound irradiation

• Kumar Godugu,
• Venkata Divya Sri Yadala,
• Mohammad Khaja Mohinuddin Pinjari,
• Trivikram Reddy Gundala,
• Lakshmi Reddy Sanapareddy and
• Chinna Gangi Reddy Nallagondu

Beilstein J. Org. Chem. 2020, 16, 1881–1900, doi:10.3762/bjoc.16.156

• positions might be due to the presence of trace metal contents and impurities. The morphology of the NDL catalyst was analyzed by scanning electron microscopy (Figure 5). The SEM images revealed that the morphology of the NDL catalyst consists of irregular shapes and sizes with a random dispersion. Further

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

Activated carbon as catalyst support: precursors, preparation, modification and characterization

• Melanie Iwanow,
• Tobias Gärtner,
• Volker Sieber and
• Burkhard König

Beilstein J. Org. Chem. 2020, 16, 1188–1202, doi:10.3762/bjoc.16.104

• properties with the preparation and modification methods. In the following, typical characterization techniques are introduced and the information obtained from the analytical methods is discussed on selected examples. Surface characterization Scanning electron microscopy (SEM): Surface morphology of

• constant. The activation process leads to an increase of oxygen, while all other elements decrease. Thus, the activation reagent (KOH) oxidizes the initial material during this step. As expected, the ammoxidation results in an enrichment of nitrogen [10]. Scanning electron microscopy with energy-dispersive

The charge-assisted hydrogen-bonded organic framework (CAHOF) self-assembled from the conjugated acid of tetrakis(4-aminophenyl)methane and 2,6-naphthalenedisulfonate as a new class of recyclable Brønsted acid catalysts

• Svetlana A. Kuznetsova,
• Alexander S. Gak,
• Yulia V. Nelyubina,
• Vladimir A. Larionov,
• Han Li,
• Michael North,
• Vladimir P. Zhereb,
• Alexander F. Smol'yakov,
• Artem O. Dmitrienko,
• Michael G. Medvedev,
• Igor S. Gerasimov,
• Ashot S. Saghyan and
• Yuri N. Belokon

Beilstein J. Org. Chem. 2020, 16, 1124–1134, doi:10.3762/bjoc.16.99

• vessel saturated with the vapors of these compounds. The absorbed material changed its PRXD reversibly, returning to its original structure after the absorbed solvent was allowed to evaporate from the sample. The morphology of uncrystallized F-1 was studied by scanning electron microscopy (SEM) analysis

Targeted photoswitchable imaging of intracellular glutathione by a photochromic glycosheet sensor

• Xianzhi Chai,
• Hai-Hao Han,
• Yi Zang,
• Jia Li,
• Xiao-Peng He,
• Junji Zhang and
• He Tian

Beilstein J. Org. Chem. 2019, 15, 2380–2389, doi:10.3762/bjoc.15.230

• broad and strong absorption makes the 2D MnO2 nanosheets a potential energy acceptor for the fluorophores which are stacked on the nanosheets plane, leading to the fluorescence quenching through FRET mechanism [32][34]. The transmission electron microscopy (TEM) image of the prepared product revealed

Morphology-tunable and pH-responsive supramolecular self-assemblies based on AB₂-type host–guest-conjugated amphiphilic molecules for controlled drug delivery

• Yang Bai,
• Cai-ping Liu,
• Di Chen,
• Long-hai Zhuo,
• Huai-tian Bu and
• Wei Tian

Beilstein J. Org. Chem. 2019, 15, 1925–1932, doi:10.3762/bjoc.15.188

• -assembly and the size of β-CD-BM2-based supramolecular self-assemblies under neutral and acidic pH were first investigated by employing transmission electron microscopy (TEM) and dynamic light scattering (DLS). The prepared β-CD-BM2 were dissolved under neutral pH solution to form FSSAs. TEM revealed that

Reversible end-to-end assembly of selectively functionalized gold nanorods by light-responsive arylazopyrazole–cyclodextrin interaction

• Maximilian Niehues,
• Patricia Tegeder and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2019, 15, 1407–1415, doi:10.3762/bjoc.15.140

• semi-micro PMMA cuvettes (BRAND). Transmission electron microscopy was performed using a Titan Themis G3 300 TEM (FEI) operating at 300 kV or a Libra 200 FE electron microscope (Zeiss) operating at 200 kV. The ζ-potential measurements were carried out on a Nano ZS Zetasizer (Malvern Instruments) at 25

N-doped carbon dots covalently functionalized with pillar[5]arenes for Fe³⁺ sensing

• Jia Gao,
• Ming-Xue Wu,
• Dihua Dai,
• Zhi Cai,
• Yue Wang,
• Wenhui Fang,
• Yan Wang and
• Ying-Wei Yang

Beilstein J. Org. Chem. 2019, 15, 1262–1267, doi:10.3762/bjoc.15.123

• to develop effective Fe3+ sensing materials [7][22][23][24]. Our current strategy suggests that CCDs with excellent selectivity for Fe3+ sensing represent a new type of advanced fluorescent sensing materials. The sizes and morphologies of CCDs and CN-dots were characterized by transmission electron

• microscopy (TEM) (Figure 1a). TEM images showed the spherical shape of CCDs with a diameter of 9 nm. For comparison, the shape of CN-dots was quasi-spherical with an average diameter of 7 nm (Figure 1b). As shown in Figure 1c, the UV–vis absorption peak of CN-dots is at 340 nm, and CP[5] has an obvious UV

Self-assembly behaviors of perylene- and naphthalene-crown macrocycle conjugates in aqueous medium

• Xin Shen,
• Bo Li,
• Tiezheng Pan,
• Jianfeng Wu,
• Yangxin Wang,
• Jie Shang,
• Yan Ge,
• Lin Jin and
• Zhenhui Qi

Beilstein J. Org. Chem. 2019, 15, 1203–1209, doi:10.3762/bjoc.15.117

•  1d). In the polar solvents MeCN and MeOH, fluorescence of 2 becomes much weaker, and is almost totally quenched in H2O. In order to observe the aggregates formed by 1 and 2 visually in solutions, transmission electron microscopy (TEM) was utilized. First, the aggregates of 1 formed in CHCl3 and MeCN

Mechanochemical synthesis of hyper-crosslinked polymers: influences on their pore structure and adsorption behaviour for organic vapors

• Sven Grätz,
• Sebastian Zink,
• Hanna Kraffczyk,
• Marcus Rose and
• Lars Borchardt

Beilstein J. Org. Chem. 2019, 15, 1154–1161, doi:10.3762/bjoc.15.112

• contents below the limit of detection (Supporting Information File 1, Figure S3). Scattering electron microscopy also revealed an agglomerated morphology of the samples (Supporting Information File 1, Figure S4). After successfully establishing the occurrence of the cross-linking reaction and investigating

• . Scanning electron microscopy (SEM/EDX) images were obtained using a Hitachi SU8020 SEM equipped with a secondary electron (SE) detector. Prior to the measurement the samples were prepared on an adhesive carbon pad and sputtered with gold to obtain the necessary electron conductivity. Thermogravimetric

Synthesis of the polyketide section of seragamide A and related cyclodepsipeptides via Negishi cross coupling

• Jan Hendrik Lang and
• Thomas Lindel

Beilstein J. Org. Chem. 2019, 15, 577–583, doi:10.3762/bjoc.15.53

• A (1, Scheme 1) [1][2], is an ideal situation for the validation of the chemoselectivity and efficiency of photoaffinity labelling. Recently, it has been determined by cryo-electron microscopy how jasplakinolide A (1) binds to F-actin and alters the actin skeleton in vivo, resulting in pronounced

Lectins of Mycobacterium tuberculosis – rarely studied proteins

• Katharina Kolbe,
• Sri Kumar Veleti,
• Norbert Reiling and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2019, 15, 1–15, doi:10.3762/bjoc.15.1

• regarded as a non-piliated genus; however, recently, studies using transmission electron microscopy (TEM) and atomic force microscopy (AFP) have identified long appendages on the surfaces of M. smegmatis and Mtb, which could be identified as pili [108][109][110]. Two different pili types were detected for

• (T4P) are surface-exposed fibers that mediate many functions in both Gram-positive and Gram-negative bacteria, including motility, adhesion to host cells, biofilm formation, DNA uptake, and protein secretion [120][121][122][123][124][125][126][127][128]. Mtb expresses T4P that appear by electron

• microscopy as rope-like bundles on the cell surface. Mature T4P are encoded by a seven gene operon, the expression of which is up-regulated during contact with A549 epithelial cells and within macrophages [111][129]. However, their significance in Mtb pathogenicity has hitherto not been further investigated