Thiazolidinones: novel insights from microwave synthesis, computational studies, and potentially bioactive hybrids

• Luan A. Martinho,
• Victor H. J. G. Praciano,
• Guilherme D. R. Matos,
• Claudia C. Gatto and
• Carlos Kleber Z. Andrade

Beilstein J. Org. Chem. 2025, 21, 2618–2636, doi:10.3762/bjoc.21.203

• behavior is not expected from hydrogen-bonded carbon atoms in aromatic rings. Since peak intensities depend on spin-lattice relaxation times, the absence of peaks implies some degree of molecular rigidity, which could be related to two factors: the viscosity of DMSO and the conjugation between the six

• ]. At first glance, it may seem that the carbon atoms in the ortho positions are equivalent to each other, as are the carbon atoms in the meta positions, which would result in two peaks in a 13C NMR spectrum. However, the torsional barrier and solvent viscosity stabilize the molecule in its most stable

Synthesis and characterization of a isothiouronium-calix[4]arene derivative: self-assembly and anticancer activity

• Giuseppe Granata,
• Loredana Ferreri,
• Claudia Giovanna Leotta,
• Giovanni Mario Pitari and
• Grazia Maria Letizia Consoli

Beilstein J. Org. Chem. 2025, 21, 2535–2541, doi:10.3762/bjoc.21.195

• temperature, η is the solvent viscosity, and R is the solute radius. The zeta potential (Z) was calculated by using Henry’s equation where UE is the electrophoretic mobility, ζ is the dielectric constant, f(Ka) is the Henry’s function, and η is the viscosity. Biological assays: Cell viability was measured by

The high potential of methyl laurate as a recyclable competitor to conventional toxic solvents in [3 + 2] cycloaddition reactions

• Ayhan Yıldırım and
• Mustafa Göker

Beilstein J. Org. Chem. 2025, 21, 2389–2415, doi:10.3762/bjoc.21.184

• conventional processes [101][102]. It is imperative to ascertain not only the cost-effective production processes of green solvents but also their static permeability, polarizability, solubility, viscosity, diffusivity, thermal behaviour and volumetric, surface or critical physicochemical properties that

Continuous-flow-enabled intensification in nitration processes: a review of technological developments and practical applications over the past decade

• Feng Zhou,
• Chuansong Duanmu,
• Yanxing Li,
• Jin Li,
• Haiqing Xu,
• Pan Wang and
• Kai Zhu

Beilstein J. Org. Chem. 2025, 21, 1678–1699, doi:10.3762/bjoc.21.132

• syringe pumps. The selection criteria must account for operational pressure thresholds, reagent rheological properties (e.g., viscosity), and required flow regimes. A representative challenge arises when handling high-viscosity nitration agents like the HNO3/H2SO4 binary acid system for which HPLC pumps

Thermodynamic equilibrium between locally excited and charge transfer states in perylene–phenothiazine dyads

• Issei Fukunaga,
• Shunsuke Kobashi,
• Yuki Nagai,
• Hiroki Horita,
• Hiromitsu Maeda and
• Yoichi Kobayashi

Beilstein J. Org. Chem. 2025, 21, 1577–1586, doi:10.3762/bjoc.21.121

• surrounding environment. Considering that Pe–PTZ(TPA)2 is significantly larger than that in the aforementioned study, and that benzene has a slightly higher viscosity than toluene (0.60 and 0.56 cP at 297 K, respectively), the time constant of 2.43 ps of the first EAS (EAS1) can be attributed to

Azide–alkyne cycloaddition (click) reaction in biomass-derived solvent Cyrene^TM under one-pot conditions

• Zoltán Medgyesi and
• László T. Mika

Beilstein J. Org. Chem. 2025, 21, 1544–1551, doi:10.3762/bjoc.21.117

• viscosity. Accordingly, the CuAAC reactions are usually performed in fossil-based common organic reaction media having high vapor pressure, toxicity, flammability, etc., which could result in several serious environmental concerns. According to the FDA guideline [14], common polar aprotic organic solvents

• it is negative in the Ames test [25]. Recently, we determined key physicochemical properties of CyreneTM and showed that it has a negligible vapor pressure (<9.6 kPa) and low viscosity (<6.8 mPa·s) at typical transition-metal-catalyzed reaction temperatures (30–140 °C) [26]. CyreneTM has been

Hydrogen-bonded macrocycle-mediated dimerization for orthogonal supramolecular polymerization

• Wentao Yu,
• Zhiyao Yang,
• Chengkan Yu,
• Xiaowei Li and
• Lihua Yuan

Beilstein J. Org. Chem. 2025, 21, 179–188, doi:10.3762/bjoc.21.10

• cooperative intermolecular forces. Zinc ion-induced coordination with the macrocycle and a terpyridinium derivative enabled orthogonal polymerization, as revealed by 1H NMR, DLS, and TEM techniques. In addition, viscosity measurements showed a transition from oligomers to polymers at the critical

• addition of the macrocycle to a G2/Zn2+ complex were consistent with the formation of supramolecular polymers. The supramolecular polymers formed were further characterized by viscosity and variable-concentration NMR experiments. One important feature of supramolecular polymers is the dependency of their

• molecular weight on the solution concentration. Further, a change in solution viscosity would reflect a change in molecular weight during the polymerization process. Thus, the specific viscosity of the linear supramolecular polymer (Scheme 1c) in CHCl3/CH3CN (1:1, v/v) was determined at 298 K (Figure 7

Emerging trends in the optimization of organic synthesis through high-throughput tools and machine learning

• Pablo Quijano Velasco,
• Kedar Hippalgaonkar and
• Balamurugan Ramalingam

Beilstein J. Org. Chem. 2025, 21, 10–38, doi:10.3762/bjoc.21.3

• discover more than ten copolymer compositions of promising 19F MRI agents that outperformed state-of-the-art materials. A rapid generation of copolymer libraries was achieved by forming a droplet flow in an automated HTE flow setup [52]. This approach not only assists in overcoming viscosity challenges in

Applications of microscopy and small angle scattering techniques for the characterisation of supramolecular gels

• Connor R. M. MacDonald and
• Emily R. Draper

Beilstein J. Org. Chem. 2024, 20, 2608–2634, doi:10.3762/bjoc.20.220

• may be assumed to provide an in situ environment. While D2O is chemically identical to H2O, it does exhibit differences in properties including density, viscosity, hydrogen-bond strength, a more pronounced hydrophobic effect. As hydrogen bonding and hydrophobicity are critical to hydrogel

• rheology alone cannot provide. By using rheo-SANS, the structural order of the micelle solutions could be determined under flow. Worm-like micelles can align under shear, however, it was shown that under sufficiently high strain a plateau in viscosity is reached before again undergoing shear-thinning under

Homogeneous continuous flow nitration of O-methylisouronium sulfate and its optimization by kinetic modeling

• Jiapeng Guo,
• Weike Su and
• An Su

Beilstein J. Org. Chem. 2024, 20, 2408–2420, doi:10.3762/bjoc.20.205

• systems, and has a promising application. In this work, we constructed a continuous flow microreactor system to determine the kinetic parameters of IO nitration, which allows precise control of temperature and residence time (Figure 1). Due to the high viscosity of the reaction system, a simple and

• impact of the high viscosity of sulfuric acid [26]. Figure 2a illustrates the scenario employing solely a T-mixer and Figure 2c shows the effect of flow rate on the conversion under this setup. Even when the flow rate was escalated to 14 mL/min, the conversion failed to stabilize at a plateau, suggesting

Cell-free protein synthesis with technical additives – expanding the parameter space of in vitro gene expression

• Tabea Bartsch,
• Stephan Lütz and
• Katrin Rosenthal

Beilstein J. Org. Chem. 2024, 20, 2242–2253, doi:10.3762/bjoc.20.192

• are not well described yet. To date, standard conditions have mainly been used for CFPS, with little systematic testing of whether conditions closer to intracellular conditions in terms of viscosity, macromolecules, inorganic ions, osmolarity, or water content are advantageous. Also, very few non

• of the intracellular environment on the function and cellular behavior of proteins are composition, viscosity, and macromolecular crowding [16], these parameters could have a strong impact on the protein synthesis performance using CFPS. For example, the addition of chemical chaperones, such as

• /ethylene glycol (EG), and choline chloride/glycerol) were chosen as additives to vary the viscosity, ion concentration, amount of macromolecules, and osmolarity in CFPS. The calculated values for the properties of the CFPS system with polymers and DES added at different concentrations are shown in Table 1

Electrochemical allylations in a deep eutectic solvent

• Sophia Taylor and
• Scott T. Handy

Beilstein J. Org. Chem. 2024, 20, 2217–2224, doi:10.3762/bjoc.20.189

• , however, RTILs are expensive compared to conventional solvents. Most of them are also quite viscous, which severely limits their use in synthetic electrochemistry [16]. These same expense and viscosity issues plague the application of RTILs in any area. Driven by this limitation, deep eutectic solvents

• decreased the viscosity. While complete conversion was still not achieved (67% conversion), it was a considerable improvement. Using glassy carbon electrodes with two equivalents of tin(II) chloride under a constant potential of 2 V, but still in CC/EG with 10 volume percent water, resulted in further

Understanding X-ray-induced isomerisation in photoswitchable surfactant assemblies

• Beatrice E. Jones,
• Camille Blayo,
• Jake L. Greenfield,
• Matthew J. Fuchter,
• Nathan Cowieson and
• Rachel C. Evans

Beilstein J. Org. Chem. 2024, 20, 2005–2015, doi:10.3762/bjoc.20.176

• viscosity, from 0.89 in H2O to 1.10 mPa⋅s in D2O [42], which is attributed to slow diffusion of micelles within the medium. Furthermore, the rate of H+/D+ exchange between the solvent and the photoswitch will decrease due to the heavier deuterium atoms in D2O, resulting in an effective weakening of the

• isomers. It is thought that this is due to X-ray-induced radiolysis of water, which produces many primary species, including H+ ions, that are known to catalyse the Z–E isomerisation reaction. By switching the H2O solvent to D2O, we observed that the increased viscosity and reduced acidification acted to

Regio- and stereochemical stability induced by anomeric and gauche effects in difluorinated pyrrolidines

• Ana Flávia Candida Silva,
• Francisco A. Martins and
• Matheus P. Freitas

Beilstein J. Org. Chem. 2024, 20, 1572–1579, doi:10.3762/bjoc.20.140

• stereochemical behavior. Consequently, various molecular properties, such as polarity, viscosity, and intra- and intermolecular interactions, are impacted by the C‒F bond. These features underlie the important role of selective fluorination in pharmaceuticals and agrochemicals development [1]. For instance

Synthesis and physical properties of tunable aryl alkyl ionic liquids based on 1-aryl-4,5-dimethylimidazolium cations

• Stefan Fritsch and
• Thomas Strassner

Beilstein J. Org. Chem. 2024, 20, 1278–1285, doi:10.3762/bjoc.20.110

• -donating substituents in different positions of the phenyl ring and the bis(trifluoromethylsulfonyl)imide (NTf2) anion. We investigated the effect of additional methyl groups in the backbone of the imidazolium core on the physical properties regarding viscosity, conductivity and electrochemical window

• aryl alkyl ionic liquid; viscosity; Introduction Ionic liquids (ILs) are a special class of solvents generally defined as salts with melting points below 100 °C [1]. Due to their unique properties, e.g., their high thermal stability and their negligible vapor pressure [2][3], ILs have found widespread

• investigate the impact on the properties of ILs. The negative impact on viscosity and conductivity due to the higher mass should be comparatively low. We investigated different substituents with electron-donating as well as electron-withdrawing properties at the aryl ring and the difference between the ortho

Preparing a liquid crystalline dispersion of carbon nanotubes with high aspect ratio

• Keiko Kojima,
• Nodoka Kosugi,
• Hirokuni Jintoku,
• Kazufumi Kobashi and
• Toshiya Okazaki

Beilstein J. Org. Chem. 2024, 20, 52–58, doi:10.3762/bjoc.20.7

• concentration of the dispersion, the materials of the substrate [34], and the viscosity of the dispersions should be adjusted. For instance, Headrick et al. fabricated highly aligned films by immersing the substrate in a solidifying solution immediately after the SWCNTs were aligned by applying shear stress to

• consistent with the Onsager theory. On the other hand we found that the order parameter of the DWCNT film, obtained from the LC dispersion, was nearly identical to that of the film composed of lower L/D SWCNTs [23]. Further optimization of experimental conditions, including viscosity of the dispersion and

• with previous studies [22][23]. Initially, 100 mg of DWCNT powder was pre-dispersed in 100 mL of Wako glycerol with a stirrer (ASONE, HPS-100PD) rotating at 500 rpm for 18 hours. During the stirring, the DWCNTs were defibrated by the shear stress of the high-viscosity glycerol [36]. After suspension in

Studying specificity in protein–glycosaminoglycan recognition with umbrella sampling

• Mateusz Marcisz,
• Sebastian Anila,
• Margrethe Gaardløs,
• Martin Zacharias and
• Sergey A. Samsonov

Beilstein J. Org. Chem. 2023, 19, 1933–1946, doi:10.3762/bjoc.19.144

• functions results principally from their unique physicochemical and structural features, including high negative charge, high viscosity and lubrication propensities, unbranched polysaccharide structures, low compressibility as well as the ability to attract and imbibe large amounts of water [17]. Unlike

Radical chemistry in polymer science: an overview and recent advances

• Zixiao Wang,
• Feichen Cui,
• Yang Sui and
• Jiajun Yan

Beilstein J. Org. Chem. 2023, 19, 1580–1603, doi:10.3762/bjoc.19.116

• optionally, a chain-transfer agent [21]. Products obtained from bulk polymerization have high optical clarity and are usually very pure [2]. The mechanism and equipment are relatively simple for a large-scale production in a short time. However, heat and mass transfer become difficult as the viscosity of the

• polymerization. The use of a solvent can lower the viscosity of the polymerization system, leading to better mass and heat transfer. Good heat transfer can reduce the Trommsdorff–Norrish effect [22]. Meanwhile, the inhibited termination reactions cause a significant increase in the overall yield

• dissolved initiators in the liquid phase during the process. A suspending agent, e.g., polyvinyl alcohol (PVA), is added to the system to prevent coalescence. The viscosity in suspension polymerization is low throughout the process which brings good heat transfer and temperature control, and therefore well

Synthesis of 5-arylidenerhodanines in L-proline-based deep eutectic solvent

• Stéphanie Hesse

Beilstein J. Org. Chem. 2023, 19, 1537–1544, doi:10.3762/bjoc.19.110

• potential environmental impacts [14]. For a synthetic purpose, the melting point of the DES and its viscosity are key parameters for the convenience of their use. Indeed, DES viscosities are generally higher than those of water and other common organic solvents and a too high viscosity can act as an

• characterized; a pH value of 10.07 was measured at 30 °C by Shah et al. [16] and a viscosity of 750 cP at 25 °C was reported by Mjalli et al. [17] (Table 1). It remains today one of the most used DES and studies on it are still conducted [14]. ChCl/glycerol (ChCl/Gly; 1:2) is another classical DES with a

• melting point of 17 °C which is more acidic and less viscous than ChCl/urea [18][19] (Table 1). In addition, proline-based natural deep eutectic solvents (NaDES) were also studied and it was shown that they presented higher viscosity values than the ChCl-based NaDES, suggesting that the HBA used for the

Light-responsive rotaxane-based materials: inducing motion in the solid state

• Adrian Saura-Sanmartin

Beilstein J. Org. Chem. 2023, 19, 873–880, doi:10.3762/bjoc.19.64

• (Figure 2b). Interestingly, the viscosity of the gels was progressively reduced due to the decrease of the physical entanglement of the polymeric chains via photodegradation. Thus, the viscoelasticity of the rotaxane-based gels could be fine-tuned by modifying the irradiation time. This visible-light

pH-Responsive fluorescent supramolecular nanoparticles based on tetraphenylethylene-labelled chitosan and a six-fold carboxylated tribenzotriquinacene

• Nan Yang,
• Yi-Yan Zhu,
• Wei-Xiu Lin,
• Yi-Long Lu and
• Wen-Rong Xu

Beilstein J. Org. Chem. 2023, 19, 635–645, doi:10.3762/bjoc.19.45

• of deacetylation greater than 95% (viscosity 100, 200 mPa·s) was purchased from Aladdin. All other reagents and solvents were purchased from Xilong Science as analytical grade and were used without further purification. TBTQ-C6 and TPE-CHO were synthesized and purified according to the previously

Preparation of β-cyclodextrin/polysaccharide foams using saponin

• Max Petitjean and
• José Ramón Isasi

Beilstein J. Org. Chem. 2023, 19, 78–88, doi:10.3762/bjoc.19.7

• technologies [23] or phytoremediation [24]. When chitosan and saponins are mixed, their foamability properties change, leading to a longer foam stability due to the higher viscosity achieved [25]. The use of chitosan to absorb saponins have been studied for different purposes. A high specific area activated

• of both lines gives us an approximate optimal foamability for a saponin concentration value of ca. 0.3%. These measurements correspond to solutions prepared using deionized water. Other factors such as the viscosity due to the polysaccharides or the ionic strength contributed by the catalyst can

• of LBG impacts the stability of the foam in a remarkable way. Finally, the solutions of xanthan are not shown in Figure 1, because their foams are very stable due to the much higher viscosity of those solutions. In fact, the liquid fraction was not even falling down, and liquid agglomeration began to

Inline purification in continuous flow synthesis – opportunities and challenges

• Jorge García-Lacuna and
• Marcus Baumann

Beilstein J. Org. Chem. 2022, 18, 1720–1740, doi:10.3762/bjoc.18.182

• the examples involve the separation of an organic phase from an aqueous one. However, two immiscible organic phases might be separated, like in the case of methanol and dodecane [49]. Solvent properties such as viscosity, interfacial tension, or salt concentrations in case of aqueous mixtures are some

On Reuben G. Jones synthesis of 2-hydroxypyrazines

• Pierre Legrand and
• Yves L. Janin

Beilstein J. Org. Chem. 2022, 18, 935–943, doi:10.3762/bjoc.18.93

• syringe injector, these slow additions were undertaken by using a syringe fitted with its 0.8 mm needle but devoid of its piston so that the rate of the addition was governed solely by gravity and the viscosity of the solution added. Thus, the addition of 5.5 mL of a 6 N solution of sodium hydroxide took

Adjusting the length of supramolecular polymer bottlebrushes by top-down approaches

• Tobias Klein,
• Franka V. Gruschwitz,
• Maren T. Kuchenbrod,
• Ivo Nischang,
• Stephanie Hoeppener and
• Johannes C. Brendel

Beilstein J. Org. Chem. 2021, 17, 2621–2628, doi:10.3762/bjoc.17.175

• , and η is the viscosity of the solvent [36]. By assuming typical values for the wall velocity, bubble radius, and viscosity of the solvent, the equation simplifies [37][38] to We exposed the BTU and BTP fibers to extended US (>1 h). No further scission could be observed after 2–3 h of US. AF4–MALLS