Silica gel with covalently attached bambusuril macrocycle for dicyanoaurate sorption from water

• Michaela Šusterová and
• Vladimír Šindelář

Beilstein J. Org. Chem. 2025, 21, 2604–2611, doi:10.3762/bjoc.21.201

• ]. In the field of anion extraction, there is growing interest in solid-phase substrates functionalized with synthetic macrocyclic receptors. These materials employ a supramolecular approach based on specific host–guest interactions between the immobilized macrocycle and the guest in solution, often

The intramolecular stabilizing effects of O-benzoyl substituents as a driving force of the acid-promoted pyranoside-into-furanoside rearrangement

• Alexey G. Gerbst,
• Sofya P. Nikogosova,
• Darya A. Rastrepaeva,
• Dmitry A. Argunov,
• Vadim B. Krylov and
• Nikolay E. Nifantiev

Beilstein J. Org. Chem. 2025, 21, 2456–2464, doi:10.3762/bjoc.21.187

• .21.187 Abstract Furanoside derivatives are broadly present in the antigenic structures of pathogenic microorganisms and play a key role in their recognition by the host immune system. Despite the high demand for vaccine and diagnostic development, their chemical synthesis remains challenging. During the

Conformational effects on iodide binding: a comparative study of flexible and rigid carbazole macrocyclic analogs

• Guang-Wei Zhang,
• Yong Zhang,
• Le Shi,
• Chuang Gao,
• Hong-Yu Li and
• Lei Xue

Beilstein J. Org. Chem. 2025, 21, 2369–2375, doi:10.3762/bjoc.21.181

• when interacting with iodine ions, and that flexible PBGs enhance the host–guest complementarity through conformational adjustments, resulting in local conformational fitting changes [25]. To determine the binding ratios and binding constants of the two structural analogs to iodine ions, we designed a

• Job plot obtained by varying the ratio of host and guest, but the total concentration of host and guest is fixed: [host] + [guest] = 5.0 mM, plotting the Job plot obtained by the chemical shift change of the host NH proton in the 1H NMR spectrum, see Figures S4 and S5 in Supporting Information File 1

• . This experiment supports a 1:1 stoichiometric binding between the guest TBAI and the host PBG in CDCl3. Then, the binding affinity of the two receptors to iodine ions was further studied, and the changes of UV–visible absorption and fluorescence spectra of the two receptors to anions in CHCl3 were

Rotaxanes with integrated photoswitches: design principles, functional behavior, and emerging applications

• Jullyane Emi Matsushima,
• Khushbu,
• Zuliah Abdulsalam,
• Udyogi Navodya Kulathilaka Conthagamage and
• Víctor García-López

Beilstein J. Org. Chem. 2025, 21, 2345–2366, doi:10.3762/bjoc.21.179

• biomembrane-compatible rotaxanes are promising for designing artificial ion transporters to address channelopathies. Song and co-workers developed a system in which the azobenzene in the axle is encapsulated within a chiral β-cyclodextrin, affording a self-locked [1]rotaxane [15]. The intramolecular host

Insoluble methylene-bridged glycoluril dimers as sequestrants for dyes

• Suvenika Perera,
• Peter Y. Zavalij and
• Lyle Isaacs

Beilstein J. Org. Chem. 2025, 21, 2302–2314, doi:10.3762/bjoc.21.176

• ][37]. Previously, we showed that the water-soluble methylene-bridged glycoluril dimer (G2M2, Figure 1)-based host displayed highest affinity and selectivity for planar aromatic cations (e.g., dyes) [38]. Most recently, we synthesized a series of water-insoluble catechol-walled acyclic cucurbit[n]uril

• of dyes (Figure 2). We also studied the previously reported host H2 [39], which is an isomer of G2W4, to potentially uncover any substituent effects (OH or OMe). For this study, we used the five dyes shown in Figure 2 (three cationic and two neutral) and employed a batch-mode experimental design

• . Before use, samples of H2, G2W1–G2W4 were repeatedly washed with water to remove TFA (monitored by 19F NMR) and activated by grinding and heating overnight at 90 °C under high vacuum. Experimentally, we incubated equimolar amounts (7.2 μmol) of each host with aqueous solutions of each dye (240 μM, 1 mL

C2 to C6 biobased carbonyl platforms for fine chemistry

• Jingjing Jiang,
• Muhammad Noman Haider Tariq,
• Florence Popowycz,
• Yanlong Gu and
• Yves Queneau

Beilstein J. Org. Chem. 2025, 21, 2103–2172, doi:10.3762/bjoc.21.165

• avoid side reactions and promoted exclusive transformation of formaldehyde into glycolic acid. The use of E. coli K-12 strains as host cells and paraformaldehyde as the starting material, led to production of GA with high conversion even at rather high concentrations (Scheme 8) [36]. Using a CuII-based

The application of desymmetric enantioselective reduction of cyclic 1,3-dicarbonyl compounds in the total synthesis of terpenoid and alkaloid natural products

• Dong-Xing Tan and
• Fu-She Han

Beilstein J. Org. Chem. 2025, 21, 2085–2102, doi:10.3762/bjoc.21.164

• Hamigera tarangaensis, and show cytotoxicity against various tumor cells. Notably, compound 11 exhibits 100% inhibition against herpes and polio viruses without significant host cell cytotoxicity [38]. Since their isolation, the synthesis of 11 and 12 have been reported by many groups [39][40][41][42][43

Chiral phosphoric acid-catalyzed asymmetric synthesis of helically chiral, planarly chiral and inherently chiral molecules

• Wei Liu and
• Xiaoyu Yang

Beilstein J. Org. Chem. 2025, 21, 1864–1889, doi:10.3762/bjoc.21.145

• potential applications in catalytic asymmetric reactions have also been showcased. Planar chirality Planarly chiral cyclophanes, a unique class of macrocyclic compounds featuring planar chirality, can be found in various natural products and are widely utilized in asymmetric catalysis, host–guest chemistry

Research progress on calixarene/pillararene-based controlled drug release systems

• Liu-Huan Yi,
• Jian Qin,
• Si-Ran Lu,
• Liu-Pan Yang,
• Li-Li Wang and
• Huan Yao

Beilstein J. Org. Chem. 2025, 21, 1757–1785, doi:10.3762/bjoc.21.139

• release systems based on host–guest selective recognition, self-assembly, and nano-valves by the use of of calixarenes and pillararenes from five perspectives: pH, light, enzyme, hypoxia, and multi-stimuli combination responses. Furthermore, the article projects the future clinical application prospects

• categorizes supramolecular chemistry-based drug-controlled release systems into the following three mechanisms: (1) Drugs are identified and combined with supramolecular hosts through host–guest interactions [23][24][25][26][27][28]. By adjusting the conditions surrounding the guest molecules, such as changes

• in pH, light, and enzyme activity, the binding affinity between the guest and host molecules can be altered, thereby achieving controlled drug release and targeted delivery. (2) Drugs are loaded into self-assembled host–guest systems [29][30][31][32]. The chemical structure or properties of the host

3,3'-Linked BINOL macrocycles: optimized synthesis of crown ethers featuring one or two BINOL units

• Somayyeh Kheirjou,
• Jan Riebe,
• Maike Thiele,
• Christoph Wölper and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2025, 21, 1719–1729, doi:10.3762/bjoc.21.134

• been studied. The pioneering works in this area by Cram, Lehn and Pedersen marked the beginning of modern supramolecular chemistry and were honoured with the Nobel Prize in Chemistry in 1987 [2][3][4]. Soon, it was realized that chiral crown ethers are highly promising host molecules for

Approaches to stereoselective 1,1'-glycosylation

• Daniele Zucchetta and
• Alla Zamyatina

Beilstein J. Org. Chem. 2025, 21, 1700–1718, doi:10.3762/bjoc.21.133

• host–pathogen interactions, cellular signaling, and pathogenesis. Accessing complex biomolecules containing nonreducing disaccharides is often hindered by difficulties in isolating them from natural sources, which can result in impure or degraded products, particularly when sensitive functional groups

• ][12][13][14] and the nucleoside antibiotic tunicamycin [15][16][17], etc. These molecules play essential roles in cell signaling, host–pathogen interactions, and pathogenesis and, being the constituent of pathogen-associated molecular patterns (PAMPs), can function as critical virulence factor [7][18

• = 365 nm. Using this novel approach, α,α-1,1'-linked Gal-Fuc thiodisaccharides, designed as bispecific ligands for the Pseudomonas aeruginosa lectins LecA and LecB, which play key roles in host cell adhesion and exhibit cytotoxic effects, were successfully synthesized [120]. Tetraacetylated α-galactose

Synthesis of an aza[5]helicene-incorporated macrocyclic heteroarene via oxidation of an o-phenylene-pyrrole-thiophene icosamer

• Yusuke Matsuo,
• Aoi Nakagawa,
• Shu Seki and
• Takayuki Tanaka

Beilstein J. Org. Chem. 2025, 21, 1561–1567, doi:10.3762/bjoc.21.119

• in detail. Keywords: cyclophane; fluorescence; heterohelicene; intramolecular oxidative coupling; Introduction Conjugated macrocyclic polyarenes have attracted significant attention due to their stimuli-responsive optoelectronic properties, dynamic structural changes, and host–guest interactions [1

Gold extraction at the molecular level using α- and β-cyclodextrins

• Susana Santos Braga

Beilstein J. Org. Chem. 2025, 21, 1116–1125, doi:10.3762/bjoc.21.89

• protons, which makes it sufficiently hydrophobic to host apolar guest molecules, forming particular adducts called inclusion compounds. One obvious consequence of inclusion is increased solubility, with another important action being the protection of the included guests against degradation from light

• the importance of a host–guest tight fit to obtain a precipitate with KAuBr4, which occurs only with α-CD. Lastly, tests with alternative alkali metals showed that two of the salts were able to afford co-precipitates with α-CD, as shown in Figure 2. In the adducts with the large-diameter alkali metal

• diffraction of single crystals (Figure 3), showing, for both 1:1 and 2:1 stoichiometries, cyanoaurate anions inside the host cavity and potassium cations interacting with hydroxy groups of adjacent cyclodextrins. The strong host–guest affinity and complex stability in the solution phase has been studied by

Supramolecular assembly of hypervalent iodine macrocycles and alkali metals

• Krishna Pandey,
• Lucas X. Orton,
• Grayson Venus,
• Waseem A. Hussain,
• Toby Woods,
• Lichang Wang and
• Kyle N. Plunkett

Beilstein J. Org. Chem. 2025, 21, 1095–1103, doi:10.3762/bjoc.21.87

• solution contained the metal BArF20 or BArF24 at a concentration of 10 times that of the HIM concentration. Gradually adding the metal BArF20 or BArF24 stock solution to the HIM stock solution in an NMR tube allowed the host-to-guest ratio to be varied while keeping the host concentration constant. With

• crystallographic confirmation of a 2:1 host–guest complex, titration data was fitted using a 2:1 model of HIM to metal BArF20 or BArF24 (Figure 7) [22][23]. The calculated cooperative association constants for 1 with LiBArF20 are 0.09 M−1 and 21522 M−1. The cooperative association constants for HIM with NaBArF24

• fluctuation of the concentration of the host and the guest, which contribute to the x-axis in the fitting process. The isothermal fitting to 2:1 models is often prone to overfitting with NMR data and is noticeable with the fit for 1. However, the general trend does correlate with the strength of the

On the photoluminescence in triarylmethyl-centered mono-, di-, and multiradicals

• Daniel Straub,
• Markus Gross,
• Mona E. Arnold,
• Julia Zolg and
• Alexander J. C. Kuehne

Beilstein J. Org. Chem. 2025, 21, 964–998, doi:10.3762/bjoc.21.80

Dicarboxylate recognition based on ultracycle hosts through cooperative hydrogen bonding and anion–π interactions

• Wen-Hui Mi,
• Teng-Yu Huang,
• Xu-Dong Wang,
• Yu-Fei Ao,
• Qi-Qiang Wang and
• De-Xian Wang

Beilstein J. Org. Chem. 2025, 21, 884–889, doi:10.3762/bjoc.21.72

• were synthesized via a one-pot strategy starting from macrocyclic precursors. Host–dicarboxylate binding was investigated using 1H NMR titrations, revealing that B4aH exhibits strong binding affinities toward a series of dicarboxylates, with association constants reaching up to 6896 M−1. The

• carboxylate heads and the submacrocycles. Additionally, the protons Hd and He on the glycol chain showed initial downfield shifts followed by upfield shifts. These discontinuous chemical shift movements suggest the host–dicarboxylate interactions and the simultaneous conformational changes in the host upon

• dicarboxylates interact with each subcavity of B4aH through their terminal anionic groups, utilizing cooperative hydrogen bonding and anion–π interactions. The optimal size matching between dicarboxylate and the host cavity, as seen with C72−, enhances the synergistic effect between the two subcavities

Unraveling cooperative interactions between complexed ions in dual-host strategy for cesium salt separation

• Zhihua Liu,
• Ya-Zhi Chen,
• Ji Wang,
• Qingling Nie,
• Wei Zhao and
• Biao Wu

Beilstein J. Org. Chem. 2025, 21, 845–853, doi:10.3762/bjoc.21.68

• /bjoc.21.68 Abstract The dual-host strategy offers a straightforward approach to ion separation, yet the nature of cooperative interactions between receptor-complexed cations and anions remains poorly understood. In this study, we utilize 18-crown-6 as a cation receptor and a tripodal hexaurea receptor

• dual-host systems for selective ion separation. Keywords: anion binding; cesium extraction; dual-host strategy; ion-pair interaction; solid–liquid extraction; Introduction Ion-pair interaction, defined as the electrostatic attraction between a positively charged cation and a negatively charged anion

• individual anion or cation receptors [21]. An alternative approach for ion separation involves the combination of an anion receptor and a cation receptor, known as the dual-host strategy [22][23][24]. Unlike ion-pair receptors, this strategy avoids the intricate, multi-step synthesis required for designing

Acyclic cucurbit[n]uril bearing alkyl sulfate ionic groups

• Christian Akakpo,
• Peter Y. Zavalij and
• Lyle Isaacs

Beilstein J. Org. Chem. 2025, 21, 717–726, doi:10.3762/bjoc.21.55

• Christian Akakpo Peter Y. Zavalij Lyle Isaacs Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States 10.3762/bjoc.21.55 Abstract We report the synthesis and characterization of a new acyclic cucurbit[n]uril (CB[n]) host C1 that features four

• alkyl sulfate ionic groups. The X-ray crystal structure of the C1·Me6CHDA complex is reported. Host C1 is significantly less soluble in water (4 mM) compared to the analogous acyclic CB[n] host M1 which features sulfonate ionic groups (346 mM). Host C1 does not undergo significant self-association

• specific guest. C1 binds more tightly to quaternary ammonium guests compared to the corresponding primary ammonium ions. Keywords: cucurbituril; host–guest chemistry; isothermal titration calorimetry; molecular container; X-ray crystallography; Introduction Molecular recognition interactions are key

Origami with small molecules: exploiting the C–F bond as a conformational tool

• Patrick Ryan,
• Ramsha Iftikhar and
• Luke Hunter

Beilstein J. Org. Chem. 2025, 21, 680–716, doi:10.3762/bjoc.21.54

Binding of tryptophan and tryptophan-containing peptides in water by a glucose naphtho crown ether

• Gianpaolo Gallo and
• Bartosz Lewandowski

Beilstein J. Org. Chem. 2025, 21, 541–546, doi:10.3762/bjoc.21.42

• tryptophan and Trp-containing peptides by 1 we performed NMR measurements on the 1:1 host–guest complexes in D2O. Upon binding of tryptophan by 1 a significant upfield shift of the aromatic protons and a slightly smaller shift, also upfield, of the α and β-Trp protons was observed (Figure 3). The aromatic

• the host as well as Coulombic interactions between the crown ether and the ammonium could be involved. Furthermore, the ITC measurements revealed that the binding of 1 with both enantiomers of H-Trp-OH is predominantly entropy-driven suggesting that the hydrophobic effect plays an important role in

Photomechanochemistry: harnessing mechanical forces to enhance photochemical reactions

• Francesco Mele,
• Ana M. Constantin,
• Andrea Porcheddu,
• Raimondo Maggi,
• Giovanni Maestri,
• Nicola Della Ca’ and
• Luca Capaldo

Beilstein J. Org. Chem. 2025, 21, 458–472, doi:10.3762/bjoc.21.33

• host to direct the photodimerization of 4.1 in a stereoselective fashion. The authors noted that, in stark contrast, the irradiation of 4.1 alone in a crystalline state yielded a mixture of isomers of 4.3 in low yield. Intriguingly, when a 4:1 ratio of 4.1 and 4.2 was used, 4.3 was obtained in 87

Beyond symmetric self-assembly and effective molarity: unlocking functional enzyme mimics with robust organic cages

• Keith G. Andrews

Beilstein J. Org. Chem. 2025, 21, 421–443, doi:10.3762/bjoc.21.30

• the past few years [20][70][235][315], and true organocatalysis is exceedingly rare [316]. Instead, catalytic systems tend to be composed of cavities that increase substrate solubility [317], or host nanoparticles [318][319][320][321][322][323][324][325][326], metals [44][327][328], photoactive groups

• host catalysis – (i) using the host as a “protecting group” to direct reactivity external to the host [187][346], and (ii) confinement of a transition-metal catalyst to take advantage of the restricted environment of the host [51][52] – neither of which resembles the enzyme-like possibility of a true

• ]. Meanwhile, cages 1 and 4 have been studied in the solution state as hosts for diamines (Figure 8B) [38][39], guests which would ostensibly degrade host imine cages or metal-organic cages [345]. Indeed, imine cages are rarely viable as solution-phase hosts [263][342][343][345]. We were also able to study the

Antibiofilm and cytotoxic metabolites from the entomopathogenic fungus Samsoniella aurantia

• Rita Toshe,
• Syeda J. Khalid,
• Blondelle Matio Kemkuignou,
• Esteban Charria-Girón,
• Paul Eckhardt,
• Birthe Sandargo,
• Kunlapat Nuchthien,
• J. Jennifer Luangsa-ard,
• Till Opatz,
• Hedda Schrey,
• Sherif S. Ebada and
• Marc Stadler

Beilstein J. Org. Chem. 2025, 21, 327–339, doi:10.3762/bjoc.21.23

• conditions on either biotic or abiotic surfaces. Structurally, biofilms are polymicrobial consortia embedded in an extracellular polymeric substance (EPS) that plays a pivotal role in surface adhesion, enhancement of gene exchange, antimicrobial resistance, and protection against host immune and inflammatory

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

• effectively applied to form orthogonal supramolecular polymers. The macrocycle-mediated connectivity was confirmed by single-crystal X-ray diffraction, which revealed a unique 2:2 binding motif between host and guest, bridged by two cationic pyridinium end groups through π-stacking interactions and other

• materials. Keywords: hydrogen-bonded macrocycle; orthogonal self-assembly; shape-persistent; supramolecular polymer; Introduction Host–guest interactions, particularly those involving macrocycles as hosts [1], have found a myriad of applications in supramolecular chemistry [2][3][4] owing to their ability

• ., metal coordination interactions and hydrogen bonding), providing access to various multiresponsive orthogonal self-assemblies or smart supramolecular polymers [24][25]. For example, the discovery of cucurbit[8]uril complexation in a 1:2 and 2:2 host–guest stoichiometry leads to a wide spectrum of

Chemical structure metagenomics of microbial natural products: surveying nonribosomal peptides and beyond

• Thomas Ma and
• John Chu

Beilstein J. Org. Chem. 2024, 20, 3050–3060, doi:10.3762/bjoc.20.253

• morphology of the host, etc. [25]. Sequence and function metagenomic approaches have been reviewed elsewhere and will not be covered herein [26][27][28]. This Perspective focuses on chemical structure metagenomics (Figure 2c), an emerging field that integrates bioinformatics, chemical synthesis, molecular