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

• . This was almost twice the 35.5% yield obtained with the mercury–amalgam method, which is currently in use by Artisan Small Scale Miners. Artisan Small Scale Miners is an association of familial and small-scaled entities across a range of countries located mainly in Africa, Asia, and South America [46

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

• pattern of assembly between HIM and metal cation in 2:1 ratio. While association with sodium leads to a polymer-like network, the lithium crystal structure was limited to dimeric assemblies of HIM. In the lithium-coordinating complex, the oxygen–lithium–oxygen bond angle is approximately 98.83

• °, displaying a closer arrangement of two HIMs. In contrast, the sodium complex exhibits a more open orientation of two HIMs with an oxygen–sodium–oxygen bond angle close to 167.98°. Lastly, a comparative study of association constants and binding energies for phenylalanine-based HIM with LiBArF20 and NaBArF24

• hypervalent iodine-based macrocyclic complex. Furthermore, we have experimentally and computationally compared the association constants of lithium tetrakis(pentafluorophenyl)borate ethyl etherate LiBArF20 and sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate NaBArF24 in the phenylalanine HIM system

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

• anticipated to exhibit high association efficiency and selectivity for large guests, driven by cooperative effects of their convergent macrocyclic elements. Dicarboxylates are crucial species in biological system and chemistry [20]. Examples such as malonate, succinate, and glutarate play key roles in

• ), (c) chemical shift changes of Ha versus titration equivalents c(dicarboxylate)/c(B4aH), and (d) association constants of host and guests. (a–c) DFT-optimized structure of the B4aH-C72− complex. The blue dotted lines represent hydrogen bonds and the black dotted lines represent anion–π interactions

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

• 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

• spectroscopic characterization of C1 along with determination of its inherent aqueous solubility and self-association properties. Next, we present the X-ray crystal structure of C1 as its C1·Me6CHDA complex. Subsequently, we describe a qualitative investigation of C1·guest and M1·guest complexation by 1H NMR

• +···−O3SO contacts with distances in the 4.4–5.4 Å range which suggests they play a supporting role during crystallization. Measurement of the self-association of C1 Before proceeding to investigate the molecular recognition properties of C1 by ITC, we wanted to determine whether C1 undergoes self

The effect of neighbouring group participation and possible long range remote group participation in O-glycosylation

• Rituparna Das and
• Balaram Mukhopadhyay

Beilstein J. Org. Chem. 2025, 21, 369–406, doi:10.3762/bjoc.21.27

Quantifying the ability of the CF₂H group as a hydrogen bond donor

• Matthew E. Paolella,
• Daniel S. Honeycutt,
• Bradley M. Lipka,
• Jacob M. Goldberg and
• Fang Wang

Beilstein J. Org. Chem. 2025, 21, 189–199, doi:10.3762/bjoc.21.11

• weak inverse association was observed between ΔGexp and ΔδDMSO–CDCl3 values for neutral hydrogen bond donors (Figure 6D). This result suggests that the CF2H···O interactions are likely to be a predominant contributor to the binding between HB donating and accepting molecules but other weak

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

Multicomponent reactions driving the discovery and optimization of agents targeting central nervous system pathologies

• Lucía Campos-Prieto,
• Aitor García-Rey,
• Eddy Sotelo and
• Ana Mallo-Abreu

Beilstein J. Org. Chem. 2024, 20, 3151–3173, doi:10.3762/bjoc.20.261

• DHPs result from the juxtaposition of nimodipine, a well-known calcium channel blocker and melatonin, a reputed antioxidant agent. This approach lies in the known association between increased cytosolic calcium levels and the formation of Aβ peptides, which are implicated in AD pathology. Calcium also

Advances in the use of metal-free tetrapyrrolic macrocycles as catalysts

• Mandeep K. Chahal

Beilstein J. Org. Chem. 2024, 20, 3085–3112, doi:10.3762/bjoc.20.257

• zero due to too strong association of trifluoroacetate with protonated porphyrin. DFT calculations suggested that the O–O bond in O2 becomes polarized upon binding in {(H4TPP2+)·(TB−)·O2}, which facilitates

Tailored charge-neutral self-assembled L₂Zn₂ container for taming oxalate

• David Ocklenburg and
• David Van Craen

Beilstein J. Org. Chem. 2024, 20, 3007–3015, doi:10.3762/bjoc.20.250

• development of effective receptors for their detection. In particular, the smallest dicarboxylate, oxalate, presents a significant importance due to its widespread presence in nature and its association with various diseases. Yet, very little attention was devoted to the recognition of oxalate with metal

Phenylseleno trifluoromethoxylation of alkenes

• Clément Delobel,
• Armen Panossian,
• Gilles Hanquet,
• Frédéric R. Leroux,
• Fabien Toulgoat and
• Thierry Billard

Beilstein J. Org. Chem. 2024, 20, 2434–2441, doi:10.3762/bjoc.20.207

• moieties is an active research field [12]. Among these emerging fluorinated groups, the association of the CF3 moiety with chalcogens is an interesting approach. In particular, the trifluoromethoxy group (CF3O) possesses valuable properties such as electronegativity [13][14], lipophilicity [15][16

Asymmetric organocatalytic synthesis of chiral homoallylic amines

• Nikolay S. Kondratyev and
• Andrei V. Malkov

Beilstein J. Org. Chem. 2024, 20, 2349–2377, doi:10.3762/bjoc.20.201

• the H-bond-donor association of catalysts 111 to the Cl− ion of the N-acylquinolinium intermediate 108, though a detailed investigation into the mechanism of the enantiodifferentiation has not been carried out (Scheme 22). In total 15 different quinolines were tested. The yields varied in the range of

Hydrogen-bond activation enables aziridination of unactivated olefins with simple iminoiodinanes

• Phong Thai,
• Lauv Patel,
• Diyasha Manna and
• David C. Powers

Beilstein J. Org. Chem. 2024, 20, 2305–2312, doi:10.3762/bjoc.20.197

• association and electrochemical data collected in the presence of increasing HFIP concentrations are consistent with H-bonding affording an increasingly strong oxidant. These results demonstrate a simple method for activating iminoiodinane reagents and indicate the potential for chemical non-innocence of

A comparison of structure, bonding and non-covalent interactions of aryl halide and diarylhalonium halogen-bond donors

• Nicole Javaly,
• Theresa M. McCormick and
• David R. Stuart

Beilstein J. Org. Chem. 2024, 20, 1428–1435, doi:10.3762/bjoc.20.125

• compounds (Scheme 1b) [21]. The amount of s-character in the orbital used by the central atom (both chalcogen and halogen) to bond with the aryl groups decreases moving down the respective group (16 and 17) [21]. We also found with a limited set of six compounds that the association constant (Ka) for the

• work (Scheme 2). Given the similarities drawn between hypervalent and halogen bonding [20], we considered the association of the diarylhalonium cations 1–8 with chloride anion as well as the association of the monovalent subunits 25–36 with chloride anion (Scheme 3). We also considered the association

• of cationic monovalent halogen-bond donors 37–40 with chloride as the imidazolium iodide is a well-established core of halogen-bonding catalysts [34][35] (Scheme 3). In general, we observed that more exergonic association of the halogen-bond donors with chloride were associated with closer X---Cl

Diameter-selective extraction of single-walled carbon nanotubes by interlocking with Cu-tethered square nanobrackets

• Guoqing Cheng and
• Naoki Komatsu

Beilstein J. Org. Chem. 2024, 20, 1298–1307, doi:10.3762/bjoc.20.113

• host–guest chemistry has advantages in terms of the rational design of the host molecules to target specific structures and the thorough removal of the dispersants, host molecules in our case, to recover pristine carbon nanotubes (CNTs) after separation. Moreover, the association constants of the

Activity assays of NnlA homologs suggest the natural product N-nitroglycine is degraded by diverse bacteria

• Kara A. Strickland,
• Brenda Martinez Rodriguez,
• Ashley A. Holland,
• Shelby Wagner,
• Michelle Luna-Alva,
• David E. Graham and
• Jonathan D. Caranto

Beilstein J. Org. Chem. 2024, 20, 830–840, doi:10.3762/bjoc.20.75

• . Other conserved positions could be required for subunit association in the active homodimer. Discussion The combined activity and characterization data indicate that each of the five homologs were similar to Vs NnlA in terms of oligomerization (Figure 2B), heme occupancy (Table 1 and Figure 3), NNG

Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

• -trinitrofluorenone (TNF) with a good association constant of 2100 M−1. Upon protonation of the pyrimidine nitrogen atom the hydrogen bond is disturbed, which should result in a conformational change to an open W-shaped form. Even though an acid-mediated hydrogen bond disruption was expected, no clear experimental

• terpyridine-bearing platinum–salphen known for their luminescence properties [41]. The closing process of the tweezers 12 was studied by NMR or UV–vis titrations with Zn2+ and other cations such as Pb2+, Fe2+, Cu2+, Eu3+, and Yb3+ indicating in all cases a 1:1 association model. The system can then be

Ligand effects, solvent cooperation, and large kinetic solvent deuterium isotope effects in gold(I)-catalyzed intramolecular alkene hydroamination

• Ruichen Lan,
• Brock Yager,
• Yoonsun Jee,
• Cynthia S. Day and
• Amanda C. Jones

Beilstein J. Org. Chem. 2024, 20, 479–496, doi:10.3762/bjoc.20.43

• thioureas and the reaction is favored at lower concentrations, an impact proposed to be due to hydrogen bonding driven self-association of the substrate [55]. In other Bronsted acid-catalyzed processes, thioureas and ureas are both effective substrates, with higher reactivity associated with thioureas

Enhanced host–guest interaction between [10]cycloparaphenylene ([10]CPP) and [5]CPP by cationic charges

• Eiichi Kayahara,
• Yoshiyuki Mizuhata and
• Shigeru Yamago

Beilstein J. Org. Chem. 2024, 20, 436–444, doi:10.3762/bjoc.20.38

• , [10]CPP⊃[5]CPP2+. While the same host–guest complex consisted of neutral CPPs, [10]CPP⊃[5]CPP, was already reported, the cationic complex showed an about 20 times higher association constant in (CDCl2)2 at 25 °C (103 mol L−1). Electrochemical and photophysical analyses and theoretical calculations

• suggested the partial electron transfer from [10]CPP to [5]CPP2+ in the complex, and this charge-transfer (CT) interaction is most likely the origin of the higher association constant of the dicationic complex than the neutral one. Keywords: charge-transfer; cycloparaphenylene; dication; host–guest

• state of the corresponding host–guest complex. Here, we report on the size complementary formation of the host–guest complex between [10]CPP and the dication of [5]CPP, [10]CPP⊃[5]CPP2+ (Figure 1c). The association constant, Ka, determined by 1H NMR titration, was about 20 times higher than that of the

Spatial arrangements of cyclodextrin host–guest complexes in solution studied by ¹³C NMR and molecular modelling

• Konstantin Lebedinskiy,
• Ivan Barvík,
• Zdeněk Tošner,
• Ivana Císařová,
• Jindřich Jindřich and
• Radim Hrdina

Beilstein J. Org. Chem. 2024, 20, 331–335, doi:10.3762/bjoc.20.33

• delivery [2][3][4], in analytical and preparative chemistry for compound separation [5] and in materials science for small molecule detection [6][7]. Association (binding) constants between the host and guest molecules [8][9][10] are typically measured by 1H NMR titration [11][12] or isothermal titration

Elucidating the glycan-binding specificity and structure of Cucumis melo agglutinin, a new R-type lectin

• Jon Lundstrøm,
• Emilie Gillon,
• Valérie Chazalet,
• Nicole Kerekes,
• Antonio Di Maio,
• Ten Feizi,
• Yan Liu,
• Annabelle Varrot and
• Daniel Bojar

Beilstein J. Org. Chem. 2024, 20, 306–320, doi:10.3762/bjoc.20.31

• experiments, nine concentrations of LacNAc (Elicityl, #GLY008) from 10 to 0 mM with a dilution coefficient of two supplemented with a fixed concentration of 0.8 µM was injected into the cell surface in multiple cycle kinetic with an association time of 500 s and a dissociation time of 12 s at a flow rate of

Substitution reactions in the acenaphthene analog of quino[7,8-h]quinoline and an unusual synthesis of the corresponding acenaphthylenes by tele-elimination

• Ekaterina V. Kolupaeva,
• Narek A. Dzhangiryan,
• Alexander F. Pozharskii,
• Oleg P. Demidov and
• Valery A. Ozeryanskii

Beilstein J. Org. Chem. 2024, 20, 243–253, doi:10.3762/bjoc.20.24

• the present work, we succeeded in filling this gap by growing crystals of base 5 from pure acetonitrile. It turned out that molecule 5 is capable of self-association through multiple C–H…N–H-bond-like contacts involving pyridyl C(3)H and C(4)H protons (Figure 5). These intermolecular contacts, whose

• overlap (с). Again, π-stacking and H-bonding (blue dotted lines) strongly dominate in this structure. Fragment of the crystal packing of neutral dipyridoacenaphthene 5 showing self-association via multiple C–H…N contacts (blue dotted lines) between three independent molecules. Structure of

Photoinduced in situ generation of DNA-targeting ligands: DNA-binding and DNA-photodamaging properties of benzo[c]quinolizinium ions

• Julika Schlosser,
• Olga Fedorova,
• Yuri Fedorov and
• Heiko Ihmels

Beilstein J. Org. Chem. 2024, 20, 101–117, doi:10.3762/bjoc.20.11

• -degenerative coupling of the dipole moments of the ligand with the DNA bases [72]. The association of the ligands 3e–g with DNA was further confirmed by the formation of negative LD bands with increasing LDR developing in the absorption range of the ligands (λ > 300 nm) (Figure 6B and Supporting Information

Using the phospha-Michael reaction for making phosphonium phenolate zwitterions

• Matthias R. Steiner,
• Max Schmallegger,
• Larissa Donner,
• Johann A. Hlina,
• Christoph Marschner,
• Judith Baumgartner and
• Christian Slugovc

Beilstein J. Org. Chem. 2024, 20, 41–51, doi:10.3762/bjoc.20.6

• 30: Experimental procedures, plot of the solid-state structure of 2f, crystallographic data, NMR spectra, UV–vis spectra and experimental and simulated time conversion plots for the zwitterion formation. Funding Funding by the Christian Doppler Research Association (Austrian Federal Ministry for