A combinatorial approach to improving the performance of azoarene photoswitches

• Joaquin Calbo,
• Aditya R. Thawani,
• Rosina S. L. Gibson,
• Andrew J. P. White and
• Matthew J. Fuchter

Beilstein J. Org. Chem. 2019, 15, 2753–2764, doi:10.3762/bjoc.15.266

• accurate enough for TS analysis. We refer to our prior publication [18] for details of the theoretical protocol used to compute half-lives. The Boltzmann distribution was applied to the energy barriers [18] and to the relative energy differences between all possible Z-conformers. Note that half-lives are

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

• incubated with BTD-4APTEG (1 μM) in live (A) and (B) and fixed cells (C) and (D). (A) and (C) show the staining distribution of the new dye BTD-4APTEG in the plasma membrane of the cells. (B) and (D) show the normal morphological aspects of the samples by phase contrast microscopy. The dye was found

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

• 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

• particular, the spatial distribution of the dielectric constant measured for thin PMMA films was described using NR as a reported dye [15]. Because NR is (i) a photostable dye, (ii) possesses convenient optical properties, such as excitation with visible light, and fluorescence, which does not overlay with

• absorption of many biomolecules, and (iii) exhibits fluorescence, which is strongly influenced by the polarity of the environment, it has been employed as a polarity probe in biological applications [16][17][18][19] and materials/nanoscience [15][20][21][22][23]. For instance, the spatial distribution of the

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

• distribution of the excited-state decays reveals the presence of a short component in the blue region of the spectrum (440–460 nm) which is not present in the remaining emission region (500–600 nm). A weak emission in this region is also observed in the steady-state fluorescence spectra obtained upon

• positive signal at <380 nm, where absorption of the E-isomer is expected, signals the occurrence of isomerization. This event is also associated to the aforementioned evolution in the visible region, clearly indicating a variation of the excited state electronic distribution. No further band-shape changes

Current understanding and biotechnological application of the bacterial diterpene synthase CotB2

• Ronja Driller,
• Daniel Garbe,
• Norbert Mehlmer,
• Monika Fuchs,
• Keren Raz,
• Dan Thomas Major,
• Thomas Brück and
• Bernhard Loll

Beilstein J. Org. Chem. 2019, 15, 2355–2368, doi:10.3762/bjoc.15.228

• three Mg2+ ions [1][22]. Notably, the PtmT1 diterpene synthase from S. platensis lacks both catalytic motifs [20][23]. The NSE/DTE motif illustrates the distribution of DTE motifs, which are predominantly found in plant TPSs, and NSE motifs, which are more common in bacterial and fungal TPSs. For the

Isolation of fungi using the diffusion chamber device FIND technology

• Benjamin Libor,
• Henrik Harms,
• Stefan Kehraus,
• Ekaterina Egereva,
• Max Crüsemann and
• Gabriele M. König

Beilstein J. Org. Chem. 2019, 15, 2191–2203, doi:10.3762/bjoc.15.216

• inserted into a tank containing 40 L of soil for experiment 1, 2 L of sea water and sediment for experiment 2, 20 L of sea water and sediment for experiment 3 and sea water for experiment 4. An aquarium powerhead pump provided water current for simulation, oxygenation and distribution purposes for

Click chemistry towards thermally reversible photochromic 4,5-bisthiazolyl-1,2,3-triazoles

• Chenxia Zhang,
• Kaori Morinaka,
• Mahmut Kose,
• Takashi Ubukata and
• Yasushi Yokoyama

Beilstein J. Org. Chem. 2019, 15, 2161–2169, doi:10.3762/bjoc.15.213

• are compared, the thermal back reaction rate of 3 is extremely faster than the others, although the central aromatic ring is common to these compounds. As shown in Table 4, neither electronic charge distribution on the carbon atoms (natural charge [42]) comprising the thermally breaking C–C bond, its

Genome mining in Trichoderma viride J1-030: discovery and identification of novel sesquiterpene synthase and its products

• Xiang Sun,
• You-Sheng Cai,
• Yujie Yuan,
• Guangkai Bian,
• Ziling Ye,
• Zixin Deng and
• Tiangang Liu

Beilstein J. Org. Chem. 2019, 15, 2052–2058, doi:10.3762/bjoc.15.202

• . viride to date. Keywords: genome mining; metabolic engineering; natural products; sesquiterpene synthase; terpenes; Trichoderma viride J1-030; Introduction Terpenoids represent the most diverse group of natural products, with a wide distribution in microorganisms, plants, insects and various marine

Attempted synthesis of a meta-metalated calix[4]arene

• Christopher D. Jurisch and
• Gareth E. Arnott

Beilstein J. Org. Chem. 2019, 15, 1996–2002, doi:10.3762/bjoc.15.195

• dichloro(p-cymene)ruthenium(II) dimer or the triazolium chloride salt already observed. As a last attempt to find evidence for the ruthenacycle, a high-resolution mass spectrum was acquired directly after the reaction was completed. The most important isotopic distribution detected was at 984.4283 Da

• , which corresponded to the expected [M − Cl]+ ion with Δmi = 2.30 ppm (Figure 4). However, this peak was very small and overlapped slightly with another isotopic distribution pattern that corresponded to [M + H − C3H6], i.e., loss of propene (see Supporting Information File 1 for a closer view of this

• ). The major peak observed had a monoisotopic mass of 1020.4040 Da which fitted the predicted value for [M + H]+ of 1020.4020 Da (Δmi = 1.95 ppm) including the isotopic distribution pattern (Figure 4). Unfortunately, whilst this could represent the ruthenacycle, the more likely assignment would be for

Reactions of 2-carbonyl- and 2-hydroxy(or methoxy)alkyl-substituted benzimidazoles with arenes in the superacid CF₃SO₃H. NMR and DFT studies of dicationic electrophilic species

• Dmitry S. Ryabukhin,
• Alexey N. Turdakov,
• Natalia S. Soldatova,
• Mikhail O. Kompanets,
• Alexander Yu. Ivanov,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2019, 15, 1962–1973, doi:10.3762/bjoc.15.191

• the formation of heteroaromatic benzyl-type dications IV, VI, and IX, respectively. Electronic characteristics, energies of HOMO/LUMO, electrophilicity indices ω [25][26], charge distribution, and contribution of atomic orbital into the LUMO of species I–IX were calculated by DFT method to estimate

Identification of optimal fluorescent probes for G-quadruplex nucleic acids through systematic exploration of mono- and distyryl dye libraries

• Xiao Xie,
• Michela Zuffo,
• Marie-Paule Teulade-Fichou and
• Anton Granzhan

Beilstein J. Org. Chem. 2019, 15, 1872–1889, doi:10.3762/bjoc.15.183

• dot distribution in the plot, the mono-styryl motif and the pyrrole substituent within the distyryl motif (1x, 7x) clearly promote the selectivity for the parallel G4 structures. On the other side, the effect of the indole motif is less clear, with most of the dyes not displaying any well-defined

• light-up data matrix for all dyes (ct DNA and cl RNA were excluded, as well as TBA and c-myb due to their low light-up factors). Color coding highlights the distribution of the dyes sharing similar structural motifs. Dual-dye conformational analysis of an extended panel of 33 DNA oligonucleotides. This

Halide metathesis in overdrive: mechanochemical synthesis of a heterometallic group 1 allyl complex

• Ross F. Koby,
• Nicholas R. Rightmire,
• Nathan D. Schley,
• Timothy P. Hanusa and
• William W. Brennessel

Beilstein J. Org. Chem. 2019, 15, 1856–1863, doi:10.3762/bjoc.15.181

• sites, the value of ∆S = +17 J mol−1 K−1 is obtained. At 298 K, the −T∆S value is −5.1 kJ mol−1. As imperfect as this approximation is (e.g., the distribution of metal ions is not completely random, and the coordination environments are not exactly the same), it does suggest one source of driving force

Transient and intermediate carbocations in ruthenium tetroxide oxidation of saturated rings

• Manuel Pedrón,
• Laura Legnani,
• Maria-Assunta Chiacchio,
• Pierluigi Caramella,
• Tomás Tejero and
• Pedro Merino

Beilstein J. Org. Chem. 2019, 15, 1552–1562, doi:10.3762/bjoc.15.158

• corresponding to TS1, TS2 and TS3 have allowed identifying changes in the electron distribution of atoms and bonds during the reaction coordinate and the precise moment in which bonds are broken and formed. The ELF analysis of the oxidation of cyclopentane (Figure 2) showed an asynchronous concerted process

A heteroditopic macrocycle as organocatalytic nanoreactor for pyrroloacridinone synthesis in water

• Piyali Sarkar,
• Sayan Sarkar and
• Pradyut Ghosh

Beilstein J. Org. Chem. 2019, 15, 1505–1514, doi:10.3762/bjoc.15.152

• issue for the stabilization of the activated complex by a hydrophobic catalyst [31]. Again, the efficiency of an organocatalyst could be enhanced by downsizing the catalyst at nanorange distribution (i.e., nanoreactor) [13][14]. This is because a nanoreactor allows for precise interactions with the

• subjected to various studies like SEM, TEM and DLS experiments. The DLS data revealed that the dispersed particles size in the aqueous phase varied from ≈60 nm to ≈105 nm (Figure 2a). Interestingly, when the same dispersion was used for the analysis of the particle size distribution on a solid surface, i.e

• using 60–120 mesh silica gel and petroleum ether/ethyl acetate mixture as eluent. We got pure products at 3–4% ethyl acetate in petroleum ether and the pure catalyst using 5% methanol in dichloromethane. Bis-amido-tris-amine macrocycle BATA-MC. (a) Number distribution plot with particle size in DLS, (b

Reaction of oxiranes with cyclodextrins under high-energy ball-milling conditions

• László Jicsinszky,
• Federica Calsolaro,
• Katia Martina,
• Fabio Bucciol,
• Maela Manzoli and
• Giancarlo Cravotto

Beilstein J. Org. Chem. 2019, 15, 1448–1459, doi:10.3762/bjoc.15.145

• and slightly waxy, which demonstrates their PG content. A comparison of DS, by 1H NMR, and the product distribution of the ESIMS data showed a Gaussian-like distribution of masses in the range of 1–11, which was independent of the target DS. The ESIMS of the neutral HPCDs resulted in a complex

• the formed polymers are in progress. Under an electron microscope, the bead polymer showed a smooth surface and a non-Gaussian particle-size distribution that was centred around 65–70 µm, while the ball-milled CDPs were completely bumpy and considerably smaller than the bead polymer, as seen in Figure

•  2 and Figure 3. Higher aggregation of particles of β-CDP was found when it had been prepared on a 2 mmol scale as compared to either the γ-CDP or β-CDP on a 20 mmol scale. The particle-size distribution, which was determined using the quasi elastic light scattering (QELS) method, was relatively

Anomeric sugar boronic acid analogues as potential agents for boron neutron capture therapy

• Daniela Imperio,
• Erika Del Grosso,
• Silvia Fallarini,
• Grazia Lombardi and
• Luigi Panza

Beilstein J. Org. Chem. 2019, 15, 1355–1359, doi:10.3762/bjoc.15.135

• lithium ion) that dissipate all their energy in a path of the order of a cell diameter (5–9 μm) in biological tissues, which gives them the potential for precise cell damage. Highly selective delivery, accumulation of boron in tumor tissues and proper subcellular distribution are required to achieve a

Bambusuril analogs based on alternating glycoluril and xylylene units

• Tomáš Lízal and
• Vladimír Šindelář

Beilstein J. Org. Chem. 2019, 15, 1268–1274, doi:10.3762/bjoc.15.124

• significant effect on the distribution of macrocycle homologues probably due to the non-reversible nature of the reaction. However, the salt was used as it facilitated precipitation of the crude product after aqueous work-up. The MALDI analysis (Supporting Information File 1, Figure S1) indicated that the

• in favor of 1a-1 which remained constant at even lower temperature. By application of the Boltzmann distribution to the conformer population, we have calculated that 1a-1 is more stable by 0.13 kcal mol−1 than 1a-2. Conformer 1a-1 is preferred probably due to its higher symmetry. Diastereomer 1b was

Understanding the unexpected effect of frequency on the kinetics of a covalent reaction under ball-milling conditions

• Ana M. Belenguer,
• Adam A. L. Michalchuk,
• Giulio I. Lampronti and
• Jeremy K. M. Sanders

Beilstein J. Org. Chem. 2019, 15, 1226–1235, doi:10.3762/bjoc.15.120

• modification from that originally proposed by Butyagin [29], in which the rate is proportional to the frequency of collision (A), and the initial activation energy (E0) for the chemical reaction. For systems in which the reaction is limited by the distribution of mechanical energy, it has been suggested that

Phylogenomic analyses and distribution of terpene synthases among Streptomyces

• Lara Martín-Sánchez,
• Kumar Saurabh Singh,
• Mariana Avalos,
• Gilles P. van Wezel,
• Jeroen S. Dickschat and
• Paolina Garbeva

Beilstein J. Org. Chem. 2019, 15, 1181–1193, doi:10.3762/bjoc.15.115

• /bjoc.15.115 Abstract Terpene synthases are widely distributed among microorganisms and have been mainly studied in members of the genus Streptomyces. However, little is known about the distribution and evolution of the genes for terpene synthases. Here, we performed whole-genome based phylogenetic

• analysis of Streptomyces species, and compared the distribution of terpene synthase genes among them. Overall, our study revealed that ten major types of terpene synthases are present within the genus Streptomyces, namely those for geosmin, 2-methylisoborneol, epi-isozizaene, 7-epi-α-eudesmol, epi-cubenol

• , caryolan-1-ol, cyclooctat-9-en-7-ol, isoafricanol, pentalenene and α-amorphene. The Streptomyces species divide in three phylogenetic groups based on their whole genomes for which the distribution of the ten terpene synthases was analysed. Geosmin synthases were the most widely distributed and were found

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

• nature of the latter. The surface area of the polymer was increased up to 1720 m2g−1 when utilizing diethyl ether (Table 1, entry 7), therefore almost doubled, while the pore volume is also growing. In the pore size distribution one can observe a shift from 0.75 nm micropores for NG-HCP to a mixture of

• higher total pore volume of 1.55 cm3g−1 due to the higher ratio of mesopores and hence, a lower share of micropore volume (0.24 cm3g−1). Also, the pore size distribution proved to be rather broad (as reported before) compared to the mechanochemically synthesised material. For both materials the overall

•  5B). A very similar behaviour is observed for both HCP samples LAG-HCP and Sol-HCP. However, the Sol-HCP shows a steeper slope of the adsorption isotherm due to the broader pore size distribution. In contrast, the LAG-HCP with the narrow PSD shows a more pronounced uptake at low relative pressures

Novel (2-amino-4-arylimidazolyl)propanoic acids and pyrrolo[1,2-c]imidazoles via the domino reactions of 2-amino-4-arylimidazoles with carbonyl and methylene active compounds

• Victoria V. Lipson,
• Tetiana L. Pavlovska,
• Nataliya V. Svetlichnaya,
• Anna A. Poryvai,
• Nikolay Yu. Gorobets,
• Erik V. Van der Eycken,
• Irina S. Konovalova,
• Svetlana V. Shiskina,
• Alexander V. Borisov,
• Vladimir I. Musatov and
• Alexander V. Mazepa

Beilstein J. Org. Chem. 2019, 15, 1032–1045, doi:10.3762/bjoc.15.101

• analysis of the bond lengths has shown that the formally single exocyclic C1–N3 bond is shorter than the double endocyclic C6–C1 bond (1.336(6) Å and 1.354(9) Å, respectively).The C1 and C6 atoms are planar indicating their sp2 hybridization. Such a distribution of electron density allows to discuss the

• indicating their sp2 hybridization. Such a distribution of electron density allows discussing the zwitter-ionic form and considering the structure of 19a as superposition of two resonance structures similar to 16a (Scheme 6). Conclusion In the described three-component reactions with aldehydes or isatins and

Fabrication, characterization and adsorption properties of cucurbit[7]uril-functionalized polycaprolactone electrospun nanofibrous membranes

• Changzhong Chen,
• Fengbo Liu,
• Xiongzhi Zhang,
• Zhiyong Zhao and
• Simin Liu

Beilstein J. Org. Chem. 2019, 15, 992–999, doi:10.3762/bjoc.15.97

• observations have been also reported for CD-functionalized nanofibers [12] and calixarene-functionalized nanofibers with high loading [20]. The diameter distribution and AFD of the PCL/CB[7] nanofibers also varied with the increase of CB[7] loading. When the mass ratio of PCL/CB[7] was 100:50, the diameter of

• electrospinning from PCL/CB[7] mixed solutions. SEM results show that bead-free nanofibers with uniform diameter distribution were obtained and the maximum CB[7] mass percentage in the composite nanofibers can reach to 66.67% (the mass ratio of PCL/CB[7] is 100:200). XRD patterns and DSC curves confirmed that PCL

• through the electrospinning technique is on the way, in order to find a real application on the removal of organic wastes in water. Representative SEM images and the corresponding diameter distribution of the nanofibers: (a) neat PCL; (b) PCL/CB[7] (100:50); (c) PCL/CB[7] (100:100); (d) PCL/CB[7] (100:150

Mechanochemical synthesis of poly(trimethylene carbonate)s: an example of rate acceleration

• Sora Park and
• Jeung Gon Kim

Beilstein J. Org. Chem. 2019, 15, 963–970, doi:10.3762/bjoc.15.93

• -milling polymerization did not allow for controlling the molecular weight distribution, resulting in a broad polydispersity (Mw/Mn) of 2.01 (Table 4, entry 5). As mentioned, fast initiation over chain propagation is one of the requirements in a controlled polymerization. While TBD could chemically enhance

Hoveyda–Grubbs catalysts with an N→Ru coordinate bond in a six-membered ring. Synthesis of stable, industrially scalable, highly efficient ruthenium metathesis catalysts and 2-vinylbenzylamine ligands as their precursors

• Kirill B. Polyanskii,
• Kseniia A. Alekseeva,
• Pavel V. Raspertov,
• Pavel A. Kumandin,
• Eugeniya V. Nikitina,
• Atash V. Gurbanov and
• Fedor I. Zubkov

Beilstein J. Org. Chem. 2019, 15, 769–779, doi:10.3762/bjoc.15.73

• across olefins [56][57]. It is worth to note in the end of this part, that we did not detect formation of chlorine-containing products (molecular peaks with the isotopic distribution characteristic for chlorine were absent in GC–MS spectra). Conclusion The present work reports an efficient method for the

Synthesis of polydicyclopentadiene using the Cp₂TiCl₂/Et₂AlCl catalytic system and thin-layer oxidation of the polymer in air

• Zhargolma B. Bazarova,
• Ludmila S. Soroka,
• Alex A. Lyapkov,
• Мekhman S. Yusubov and
• Francis Verpoort

Beilstein J. Org. Chem. 2019, 15, 733–745, doi:10.3762/bjoc.15.69

• (see Scheme 2 and Scheme 3). According to GPC, the molecular weight of the polymers was in the range of (10–50)·103 with a molecular weight distribution of about 2–3. Figure 8 displays the GPC traces for two samples of DCPD polymers obtained at a concentration of Cp2TiCl2/AlEt2Cl complex 2 mmol/L

• (thin layer on silicon) with respect to intensities of adsorption bands at 1410 and 700 cm−1. The distribution of oxygen concentration in the polymer layer: 1 – a layer of oxidized cross-linked polymer; 2 – a layer of non-oxidized polymer. Dependence of the ratio of adsorption bands at 1700 and 700 cm−1