Curcuminoid–BF₂ complexes: Synthesis, fluorescence and optimization of BF₂ group cleavage

• Henning Weiss,
• Jeannine Reichel,
• Helmar Görls,
• Kilian Rolf Anton Schneider,
• Mathias Micheel,
• Michael Pröhl,
• Michael Gottschaldt,
• Benjamin Dietzek and
• Wolfgang Weigand

Beilstein J. Org. Chem. 2017, 13, 2264–2272, doi:10.3762/bjoc.13.223

• (sharp singlet) could be assigned to BF4− as the most common hydrolysis byproduct by comparison with HBF4 in DMSO-d6. X-ray crystallography Compounds 2f, 2g and 2h were also characterized by X-ray diffraction methods. Crystals suitable for analysis were grown by slow diffusion of n-hexane into CH2Cl2

Main group mechanochemistry

• Agota A. Gečiauskaitė and
• Felipe García

Beilstein J. Org. Chem. 2017, 13, 2068–2077, doi:10.3762/bjoc.13.204

• obtained in small-scale via salt metathesis reactions due to poor starting material (SrI2 and K[Cp′]) solubility in ether solution. LAG provides a high yielding synthetic methodology circumventing the scalability issues associated with the inefficient diffusion of reactants in large-scale solution-based

Solid-state mechanochemical ω-functionalization of poly(ethylene glycol)

• Michael Y. Malca,
• Pierre-Olivier Ferko,
• Tomislav Friščić and
• Audrey Moores

Beilstein J. Org. Chem. 2017, 13, 1963–1968, doi:10.3762/bjoc.13.191

• leading to unwanted chain lengthening during the derivatization process. Under mechanochemical conditions, diffusion limitation may favor the reactivity of small molecule reagents over the intermolecular reaction between two polymers to afford the kinetically-favorable end-products, in contrast to solvent

β-Cyclodextrin- and adamantyl-substituted poly(acrylate) self-assembling aqueous networks designed for controlled complexation and release of small molecules

• Liang Yan,
• Duc-Truc Pham,
• Philip Clements,
• Stephen F. Lincoln,
• Jie Wang,
• Xuhong Guo and
• Christopher J. Easton

Beilstein J. Org. Chem. 2017, 13, 1879–1892, doi:10.3762/bjoc.13.183

• diffusion within the particular EO sample and its interaction with the dialysis membrane as it passes through its pores. Similar profiles characterize the release of MO and MR from PAA and adamantyl substituted PAA (Figure 12(ii) and 12(iii), respectively,) and a similar interpretation applies. However, the

• membrane diffusion apparatus (Figure S37, Supporting Information File 1) in which a 3.5 kDa molecular weight cut-off dialysis membrane (Spectr/Por 3) of surface area 7.0 cm2 separated 5.0 cm3 of the dye containing solution (made up in Na2HPO4/KH2PO4 buffer at pH 7.0 and I = 0.10 mol dm−3 with MR, MO or EO

A recursive microfluidic platform to explore the emergence of chemical evolution

• David Doran,
• Marc Rodriguez-Garcia,
• Rebecca Turk-MacLeod,
• Geoffrey J. T. Cooper and
• Leroy Cronin

Beilstein J. Org. Chem. 2017, 13, 1702–1709, doi:10.3762/bjoc.13.164

• observed, both in our own work and in the literature that limited exchange of material can occur between neighbouring water-in-oil microdroplets (see Figure 3). The rate of diffusion of molecules between microdroplets is inversely proportional to their molecular weight, with the result that microdroplets

Block copolymers from ionic liquids for the preparation of thin carbonaceous shells

• Sadaf Hanif,
• Bernd Oschmann,
• Dmitri Spetter,
• Muhammad Nawaz Tahir,
• Wolfgang Tremel and
• Rudolf Zentel

Beilstein J. Org. Chem. 2017, 13, 1693–1701, doi:10.3762/bjoc.13.163

• incorporation of conductive carbon was shown to be a successful strategy [27]. While nanostructuring of inorganic particles increases the electrode/electrolyte contact area and allows an easier diffusion of the cations, the incorporation of electronic transport pathways allows an improved charging of the

• the nanoparticle synthesis avoiding the aggregation of nanoparticles, which would lower the surface area and increases the diffusion distances in the final particles for Na or Li ions. For the in situ nanoparticle synthesis TiCl4 was dissolved in benzyl alcohol and the block copolymer was added and

The chemistry and biology of mycolactones

• Matthias Gehringer and
• Karl-Heinz Altmann

Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159

• against competing microorganisms was not the evolutionary driver for the emergence of the toxin. It is generally assumed in the literature that mycolactones reach their cellular targets by passive diffusion [91]. Based on competition experiments with the fluorescent, boron-dipyrromethene (BODIPY)-labeled

Chemical systems, chemical contiguity and the emergence of life

• Terrence P. Kee and
• Pierre-Alain Monnard

Beilstein J. Org. Chem. 2017, 13, 1551–1563, doi:10.3762/bjoc.13.155

• derivatives and even stabilize them [63]. The same observation was made for ribose over other sugars. Moreover, when the permeability of fatty acid vesicle bilayers towards sugars was examined, ribose was determined to have the highest diffusion rates among aldopentoses or hexoses [64], a fact that could also

• composed of several types of “prebiotic” fatty acids and co-surfactants. That is, the vesicles could have retained the primer/template system while activated monomers crossed the vesicle bilayers by passive diffusion. Similarly, amino acids could be dimerized within vesicles [86]. In related experiments

2-Methyl-2,4-pentanediol (MPD) boosts as detergent-substitute the performance of ß-barrel hybrid catalyst for phenylacetylene polymerization

• Julia Kinzel,
• Daniel F. Sauer,
• Marco Bocola,
• Marcus Arlt,
• Tayebeh Mirzaei Garakani,
• Andreas Thiel,
• Klaus Beckerle,
• Tino Polen,
• Jun Okuda and
• Ulrich Schwaneberg

Beilstein J. Org. Chem. 2017, 13, 1498–1506, doi:10.3762/bjoc.13.148

• attractive. When using other stabilizing agents, micelle formation decreases the activity by building up an additional diffusion barrier. Furthermore, the formed micelles are influenced by the substrate leading to protein precipitation. The usage of the amphiphilic stabilizer MPD avoided protein

Framing major prebiotic transitions as stages of protocell development: three challenges for origins-of-life research

• Ben Shirt-Ediss,
• Sara Murillo-Sánchez and
• Kepa Ruiz-Mirazo

Beilstein J. Org. Chem. 2017, 13, 1388–1395, doi:10.3762/bjoc.13.135

• for the sustainability of any type of cell [7][8]. Furthermore, this more encompassing approach to life is fully congruent with other insights coming from investigations on reaction–diffusion processes in biology, which have revealed, since the pioneering work of Turing [9], the enormous potential of

• coupling chemistry with the constrained spatial diffusion of the molecules involved [10][11]. Therefore, given the cellular nature of all life known on our planet, and given the importance of compartmentalized chemistries for understanding many biological phenomena, it may be productive to try origin-of

• negative and positive feedback loops (autocatalytic cycles) that can take place within the internal water pool, the presence of closed lipid bilayers strongly restricts the free diffusion of the various soluble species involved, allows the selective passage of precursors and excludes water in limited areas

Mechanochemistry-assisted synthesis of hierarchical porous carbons applied as supercapacitors

• Desirée Leistenschneider,
• Nicolas Jäckel,
• Felix Hippauf,
• Volker Presser and
• Lars Borchardt

Beilstein J. Org. Chem. 2017, 13, 1332–1341, doi:10.3762/bjoc.13.130

• influence of the pore size and the pore structure on (electro)sorption in energy storage devices [15][16][17]. Moreover, purely microporous carbons suffer from diffusion limitations resulting in low electrochemical performances at high charge/discharge rates [4][18][19]. Larger pores, like mesopores, or

• ), the porogens could be partially removed by HF (CarbHF-LA-3). We assume that the carbon matrix obtained from a solvent-free approach is possibly denser and thus the diffusion of HF to the particles is inhibited (incomplete removal). This aligns with the assumption that the energy-input and accordingly

Detection of therapeutic radiation in three-dimensions

• John A. Adamovics

Beilstein J. Org. Chem. 2017, 13, 1325–1331, doi:10.3762/bjoc.13.129

• ferrous/agarose/xylenol orange (FAX) gel shows visible-light absorption at 440 nm; after exposure to ionizing radiation, there is an increase in absorption at 585 nm. Even though diffusion has been diminished it continues to be an issue [12]. These diffusion limitations were overcome in a gel matrix by

One-pot synthesis of block-copolyrotaxanes through controlled rotaxa-polymerization

• Jessica Hilschmann,
• Gerhard Wenz and
• Gergely Kali

Beilstein J. Org. Chem. 2017, 13, 1310–1315, doi:10.3762/bjoc.13.127

• of the polyrotaxanes [41]. This peak broadening was indeed observed in the 1H NMR spectra of both polymers (Figure 1b and Supporting Information File 1) and was regarded as the first indication for a polyrotaxane structure. In addition, the agreement of the diffusion coefficients D for all proton NMR

• signals of the polymeric axis, RAMEB and the stopper in the diffusion-ordered NMR spectrum (DOSY, Figure 1b) further proved the existence of the polyrotaxane [42]. The D values of 1.0 × 10−10 and 4.1 × 10−11 m2/s were found for TRIS-AAm, and HEMA stoppered polyrotaxanes, respectively. The weight average

• –2.3 and 5.0 ppm and of polyHEMA at 0.7–2.1 and 3.3–4.0 ppm. The noticeable peak broadening again is indicative of the formation of ABA triblock-copolyrotaxane. The DOSY measurements were carried out for the block-copolymer polyrotaxanes in DMSO. The same diffusion coefficients were detected for all

Strategies in megasynthase engineering – fatty acid synthases (FAS) as model proteins

• Manuel Fischer and
• Martin Grininger

Beilstein J. Org. Chem. 2017, 13, 1204–1211, doi:10.3762/bjoc.13.119

• translocation of the cargo to the downstream modules in modular PKS, which largely accounts for the assembly-line character of these proteins (Figure 2c). As part of the multienzyme compartment, the mode of ACP action is best described as enabling limited diffusion within a conformational space that is

• specificity of the system via domain–domain interactions, evolution has likely not selected for strict substrate specificity as compared to diffusion-loaded proteins, and megasynthases might be inherently substrate tolerant [53][54][55]. Preserve-and-adapt approach on the example of FAS Given the detailed

Towards open-ended evolution in self-replicating molecular systems

• Herman Duim and
• Sijbren Otto

Beilstein J. Org. Chem. 2017, 13, 1189–1203, doi:10.3762/bjoc.13.118

• , with potential impact on evolutionary behavior [40]. Another interesting dynamic emergent property of self-replicating systems was demonstrated by Philp and coworkers [41]. They showed how self-replicating molecules can create a reaction-diffusion front when seeded to a homogeneous mixture of building

Glycoscience@Synchrotron: Synchrotron radiation applied to structural glycoscience

• Serge Pérez and
• Daniele de Sanctis

Beilstein J. Org. Chem. 2017, 13, 1145–1167, doi:10.3762/bjoc.13.114

• transport proteins GLUTs are responsible for the diffusion of glucose, galactose, fructose, urate, myoinositol, and dehydroascorbic acid. SGLTs are sodium-glucose symporters that couple the transport of glucose to sodium ions. SWEETs have been characterized the most recently. Major carbohydrate transporters

• shorter than the time scale of substrate diffusion in the crystals. For example, when UDP-GalNAc was soaked for 24 minutes, experiments resulted in structures with UDP-GalNAc in several conformations that are difficult to interpret. The “freeze-trigger” route was started using a series of cage compounds

Molecular-level architectural design using benzothiadiazole-based polymers for photovoltaic applications

• Vinila N. Viswanathan,
• Arun D. Rao,
• Upendra K. Pandey,
• Arul Varman Kesavan and
• Praveen C. Ramamurthy

Beilstein J. Org. Chem. 2017, 13, 863–873, doi:10.3762/bjoc.13.87

• obtained. The active layer morphology in polymer solar cells is crucial and can drastically affect the performance of the devices. For optimum performance of an OPV device, the phase-separated donor and acceptor domain sizes should be twice the exciton diffusion length, which is typically of the order of 7

Continuous-flow processes for the catalytic partial hydrogenation reaction of alkynes

• Carmen Moreno-Marrodan,
• Francesca Liguori and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2017, 13, 734–754, doi:10.3762/bjoc.13.73

• wall and minimize diffusion limits (Figure 2). Without bubbles, the yield of 4a would have been ca. 57% at the same residence time. The catalyst was used for weeks without significant deactivation. 1-Cyclohexyl-2-methyl-3-butyn-1-ol In the course of their studies on diastereoselective chain-elongation

• from a diffusion-controlled to kinetic-limited regime [163][181]. The non-accumulation of co-products adsorbed on the catalyst surface may also significantly contribute to the minimization of active site inhibition under the conditions of continuous flow [27]. Flow reactor design. Performance

Membrane properties of hydroxycholesterols related to the brain cholesterol metabolism

• Malte Hilsch,
• Ivan Haralampiev,
• Peter Müller,
• Daniel Huster and
• Holger A. Scheidt

Beilstein J. Org. Chem. 2017, 13, 720–727, doi:10.3762/bjoc.13.71

• the membrane bilayer, which guides their ability to cross the blood–brain barrier. This process consists of three steps at the membrane level, (i) incorporation of sterols into the plasma membrane, (ii) their transbilayer diffusion and (iii) their release from the membrane. With regard to the transfer

• sterols, it is generally assumed that cholesterol traverses the bilayer very rapidly by passive diffusion, although at certain conditions, e.g., special membrane compositions, its transbilayer movement could be compounded (see [35]). For hydroxycholesterols, the transbilayer movement has not been

• diffusion of dithionite [18][19][27]. The assay was performed in a similar manner to the procedure described in [19]. Briefly, LUVs containing POPC and 0.5 mol % NBD-PC without or with cholesterol or the respective hydroxycholesterol (molar ratio 0.8:0.2) were prepared. The NBD fluorescence intensity of 33

Fluorescent carbon dots from mono- and polysaccharides: synthesis, properties and applications

• Stephen Hill and
• M. Carmen Galan

Beilstein J. Org. Chem. 2017, 13, 675–693, doi:10.3762/bjoc.13.67

• anion is one of the key reactive species which is implicated in various metabolic and physiological processes [35]. Thus, it is important to provide analytical methods to detect and quantify its presence, however, due to its high reactivity, low concentration levels and quick diffusion, it has been

Contribution of microreactor technology and flow chemistry to the development of green and sustainable synthesis

• Flavio Fanelli,
• Giovanna Parisi,
• Leonardo Degennaro and
• Renzo Luisi

Beilstein J. Org. Chem. 2017, 13, 520–542, doi:10.3762/bjoc.13.51

• following characteristics: a) fast mixing: in a flow microreactor, in striking contrast to batch conditions, mixing takes place by molecular diffusion so that a concentration gradient can be avoided; b) high surface-to-volume ratio: the microstructure of microreactors allows for a very rapid heat transfer

NMR reaction monitoring in flow synthesis

• M. Victoria Gomez and
• Antonio de la Hoz

Beilstein J. Org. Chem. 2017, 13, 285–300, doi:10.3762/bjoc.13.31

• product is continuously eluted from the end of the flow reactor. This approach can be used from microscale to laboratory scale and even to production scale [4][5]. Some important advantages of flow chemistry are: Diffusion is clearly improved with regard to chemistry in batch (reagents and products), thus

Highly bulky and stable geometry-constrained iminopyridines: Synthesis, structure and application in Pd-catalyzed Suzuki coupling of aryl chlorides

• Yi Lai,
• Zhijian Zong,
• Yujie Tang,
• Weimin Mo,
• Nan Sun,
• Baoxiang Hu,
• Zhenlu Shen,
• Liqun Jin,
• Wen-hua Sun and
• Xinquan Hu

Beilstein J. Org. Chem. 2017, 13, 213–221, doi:10.3762/bjoc.13.24

• by slow diffusion of diethyl ether to a saturated dichloromethane solution and the molecular structure in solid state was determined by X-ray diffraction [73]. Presented in Figure 2, the molecular structure and the predicted conformation was unambiguously confirmed. The same as before, the complexes

Dynamics and interactions of ibuprofen in cyclodextrin nanosponges by solid-state NMR spectroscopy

• Monica Ferro,
• Franca Castiglione,
• Nadia Pastori,
• Carlo Punta,
• Lucio Melone,
• Walter Panzeri,
• Barbara Rossi,
• Francesco Trotta and
• Andrea Mele

Beilstein J. Org. Chem. 2017, 13, 182–194, doi:10.3762/bjoc.13.21

• isolated S spins and an extended network of coupled I spins. The heat capacity of the rare S spins is much lower than that of I spins. According to this model, the spins I are characterized by a rapid spin diffusion so that they behave as a single spin system at a uniform spin temperature. After the

• *–S model, the reservoir of the I (1H) nuclei surrounding a given S (13C) nucleus is divided into two subsets: I* indicates the protons closest to the observed S nucleus, I the nuclei at longer distances. This model was proposed to explain the case when the proton spin diffusion rate 1/TDiff is not

• fast enough so that the I spins do not behave as a whole spin system. The I*–S spin pairs are isolated from the spin network and exchange polarization in an oscillatory mode. The oscillations are damped by the spin-diffusion contact with the whole I spin system. A schematic representation of the

Poly(ethylene glycol)s as grinding additives in the mechanochemical preparation of highly functionalized 3,5-disubstituted hydantoins

• Andrea Mascitti,
• Massimiliano Lupacchini,
• Ruben Guerra,
• Ilya Taydakov,
• Lucia Tonucci,
• Nicola d’Alessandro,
• Frederic Lamaty,
• Jean Martinez and
• Evelina Colacino

Beilstein J. Org. Chem. 2017, 13, 19–25, doi:10.3762/bjoc.13.3

• instead of PEGs as additive (Table 1, entry 14). As a result, the effect of using different end terminal groups was not markedly significant, the yield was a function of the average molecular weight of the PEG used: HO-PEG-5000-OH (Table 1, entry 11) was probably too viscous to allow the diffusion of