BINOL as a chiral element in mechanically interlocked molecules

• Matthias Krajnc and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2022, 18, 508–523, doi:10.3762/bjoc.18.53

• amino acids N-Boc-leucine, N-Boc-proline, and N-Boc-tryptophane were used. Overall, rotaxane 64a shows lower association constants (K = 138–2589 M−1) with preference for the (R)-isomers of the guest molecules (K(S)/K(R) = 0.29–0.66). In contrast, rotaxane 64b preferentially binds the (S)-isomers (K(S)/K

• (R) = 1.62–2.93) and shows higher association constants (K = 1465–4990 M−1), probably due to additional interactions with the functionalized thread. Comparison with the macrocycle (S)-61-Me22+ (K = 423–4961 M−1, K(S)/K(R) = 0.66–0.70) shows that the interlocked nature of the rotaxane hosts gives rise

• the enantioselective Michael addition with different rotaxane catalysts (S)-56a/56b/57a/57b and their non-interlocked counterparts. Synthesis of Beer´s [2]rotaxanes 64a/b for anion recognition. Association constants of different anions (used as the Bu4N+ salts) to the [2]rotaxanes (S)-64a/b and the

Synthesis of 3,4,5-trisubstituted isoxazoles in water via a [3 + 2]-cycloaddition of nitrile oxides and 1,3-diketones, β-ketoesters, or β-ketoamides

• Md Imran Hossain,
• Md Imdadul H. Khan,
• Seong Jong Kim and
• Hoang V. Le

Beilstein J. Org. Chem. 2022, 18, 446–458, doi:10.3762/bjoc.18.47

• copies of 1H, 13C, and 19F NMR spectra. Funding This work was supported by the American Association of Colleges of Pharmacy (2018 New Investigator Award to H. V. L.), the National Institute of General Medical Sciences (P30GM122733 pilot project award to H. V. L.), and funds from the Department of

Tetraphenylethylene-embedded pillar[5]arene-based orthogonal self-assembly for efficient photocatalysis in water

• Zhihang Bai,
• Krishnasamy Velmurugan,
• Xueqi Tian,
• Minzan Zuo,
• Kaiya Wang and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2022, 18, 429–437, doi:10.3762/bjoc.18.45

• corresponds to a 1:1 binding stoichiometric ratio between G and m-TPEWP5 in the aqueous solution. Furthermore, the association constant (Ka) [36] was calculated to be 8.62 × 104 M−1 based on the UV–vis titration experiment (Figure S4, Supporting Information File 1). This result further confirmed that the

Green synthesis of C5–C6-unsubstituted 1,4-DHP scaffolds using an efficient Ni–chitosan nanocatalyst under ultrasonic conditions

• Soumyadip Basu,
• Sauvik Chatterjee,
• Suman Ray,
• Suvendu Maity,
• Prasanta Ghosh,
• Asim Bhaumik and
• Chhanda Mukhopadhyay

Beilstein J. Org. Chem. 2022, 18, 133–142, doi:10.3762/bjoc.18.14

• Soumyadip Basu Sauvik Chatterjee Suman Ray Suvendu Maity Prasanta Ghosh Asim Bhaumik Chhanda Mukhopadhyay Department of Chemistry, University of Calcutta, 92 APC Road, Kolkata-700009, India Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700032

Effect of a twin-emitter design strategy on a previously reported thermally activated delayed fluorescence organic light-emitting diode

• Ettore Crovini,
• Zhen Zhang,
• Yu Kusakabe,
• Yongxia Ren,
• Yoshimasa Wada,
• Bilal A. Naqvi,
• Prakhar Sahay,
• Tomas Matulaitis,
• Stefan Diesing,
• Ifor D. W. Samuel,
• Wolfgang Brütting,
• Katsuaki Suzuki,
• Hironori Kaji,
• Stefan Bräse and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2021, 17, 2894–2905, doi:10.3762/bjoc.17.197

• (TADFlife) for funding this project. Further support was obtained by the Helmholtz Association Program at the Karlsruhe Institute of Technology (KIT). The German Research Foundation (formally Deutsche Forschungsgemeinschaft DFG) in the framework of SFB1176 Cooperative Research Centre "Molecular Structuring

Synthesis of a novel aminobenzene-containing hemicucurbituril and its fluorescence spectral properties with ions

• Qingkai Zeng,
• Qiumeng Long,
• Jihong Lu,
• Li Wang,
• Yuting You,
• Xiaoting Yuan,
• Qianjun Zhang,
• Qingmei Ge,
• Hang Cong and
• Mao Liu

Beilstein J. Org. Chem. 2021, 17, 2840–2847, doi:10.3762/bjoc.17.195

• association constant up to (2.1 ± 0.3) × 104 M−1. Meanwhile, this macrocycle showed no obvious or only slight enhancement of the fluorescence intensity with selected anions. Keywords: amidobenzene-containing macrocycle; hemicucurbituril; host–guest interaction; macrocycle; modification; Introduction

• initially studied. Among the metal cations examined, the fluorescence intensity of macrocycle 4 quenched significantly when adding the corresponding equivalents of Fe3+ and Cu2+. Notably, this macrocyclic host molecule formed 1:1 complexes with Fe3+ in DMF with an association constant up to (2.1 ± 0.3

• intensity. Evidenced by the fluorescence titration and Job’s plot experiments (Figure 4, bottom inset), aminobenzene-containing hemicucurbituril 4 interacts with Fe3+ and Cu2+ by forming a 1:1 complex in DMF solution. After depicting non-linear fitting curve and based on the titration data, the association

GlycoBioinformatics

• Kiyoko F. Aoki-Kinoshita,
• Frédérique Lisacek,
• Niclas Karlsson,
• Daniel Kolarich and
• Nicolle H. Packer

Beilstein J. Org. Chem. 2021, 17, 2726–2728, doi:10.3762/bjoc.17.184

• , type and linkage of glycoconjugate (e.g., N-linked, O-linked glycoprotein, glycolipid, proteoglycan), association with, and regulation of, expression in particular tissues or cell types, and interaction with biological surroundings. With this definition, it is obvious that glycobioinformatics is

Halides as versatile anions in asymmetric anion-binding organocatalysis

• Lukas Schifferer,
• Martin Stinglhamer,
• Kirandeep Kaur and
• Olga García Macheño

Beilstein J. Org. Chem. 2021, 17, 2270–2286, doi:10.3762/bjoc.17.145

• only a spectator linking the substrate and catalyst in the presence of an external nucleophile, halides can also be tuned to participate as the nucleophile in certain reactions. In theory, the close association of the catalyst and the anionic nucleophile might allow for better stereocontrol. An early

Constrained thermoresponsive polymers – new insights into fundamentals and applications

• Patricia Flemming,
• Alexander S. Münch,
• Andreas Fery and
• Petra Uhlmann

Beilstein J. Org. Chem. 2021, 17, 2123–2163, doi:10.3762/bjoc.17.138

Electron-rich triarylphosphines as nucleophilic catalysts for oxa-Michael reactions

• Susanne M. Fischer,
• Simon Renner,
• A. Daniel Boese and
• Christian Slugovc

Beilstein J. Org. Chem. 2021, 17, 1689–1697, doi:10.3762/bjoc.17.117

• acquiring the 31P NMR spectra, Petra Hofstadler for pre-studies and Karin Ratzenböck for discussion. Funding Funding by the Christian Doppler Research Association (Austrian Federal Ministry for Digital and Economic Affairs and the National Foundation for Research, Technology and Development) is gratefully

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

• ., magnesium ions), and achieve remarkably complex folded structures. Nevertheless, the electrostatic repulsion is the main force that disfavors folding and association of nucleic acids. With this consideration in mind, neutral PNA was expected to have superior binding to negatively charged nucleic acids due

Icilio Guareschi and his amazing “1897 reaction”

• Gian Cesare Tron,
• Alberto Minassi,
• Giovanni Sorba,
• Mara Fausone and
• Giovanni Appendino

Beilstein J. Org. Chem. 2021, 17, 1335–1351, doi:10.3762/bjoc.17.93

A new glance at the chemosphere of macroalgal–bacterial interactions: In situ profiling of metabolites in symbiosis by mass spectrometry

• Marine Vallet,
• Filip Kaftan,
• Veit Grabe,
• Fatemeh Ghaderiardakani,
• Simona Fenizia,
• Aleš Svatoš,
• Georg Pohnert and
• Thomas Wichard

Beilstein J. Org. Chem. 2021, 17, 1313–1322, doi:10.3762/bjoc.17.91

• similarity with standards. Using combined imaging mass spectrometry and confocal laser scanning microscopy, we then linked the chemical and microscopic observations that characterise the symbiotic association (cLSM). Results and Discussion Comparative metabolomics using AP-SMALDI-HRMS identifies metabolites

Synthesis of 10-O-aryl-substituted berberine derivatives by Chan–Evans–Lam coupling and investigation of their DNA-binding properties

• Peter Jonas Wickhorst,
• Mathilda Blachnik,
• Denisa Lagumdzija and
• Heiko Ihmels

Beilstein J. Org. Chem. 2021, 17, 991–1000, doi:10.3762/bjoc.17.81

• , specifically 13- and 9-substituted berberine derivatives have gained much interest as selective DNA ligands that specifically target quadruplex DNA (G4-DNA) [23][24][25][26][27][28][29], i.e., non-canonical, biologically relevant DNA structures that are formed by the association of four guanine-rich DNA

• Information File 1). Only the absorption of compound 5a increased upon association with ct DNA. In general, a significant red shift of the absorption bands was observed during all titrations, which was more pronounced in the presence of 22AG (∆λ = 18–24 nm) than in the presence of ct DNA (∆λ = 8–12 nm

• ). Therefore, it is proposed that the association with the DNA causes a similar effect. Hence, the slightly increased emission intensity of the ligands 5a–d upon addition of DNA supposedly originates from the restricted conformational freedom of the ligand within the DNA binding pocket, which suppresses the

Synthetic reactions driven by electron-donor–acceptor (EDA) complexes

• Zhonglie Yang,
• Yutong Liu,
• Kun Cao,
• Xiaobin Zhang,
• Hezhong Jiang and
• Jiahong Li

Beilstein J. Org. Chem. 2021, 17, 771–799, doi:10.3762/bjoc.17.67

• depends on the association of eosin Y and oxidant 4 to a donor–acceptor EY–4 ground-system complex (high reactivity). Due to the ability of aryl groups to stabilize the formed alkenyl radical, this protocol could control regioselectivity efficiently with unsymmetrical alkynes. In addition, EPR

DNA with zwitterionic and negatively charged phosphate modifications: Formation of DNA triplexes, duplexes and cell uptake studies

• Yongdong Su,
• Maitsetseg Bayarjargal,
• Tracy K. Hale and
• Vyacheslav V. Filichev

Beilstein J. Org. Chem. 2021, 17, 749–761, doi:10.3762/bjoc.17.65

• ammonium group, providing a zwitterionic phosphate mimic. The resistance to enzymatic degradation, a higher thermal stability, and a faster association that was independent of ionic strength was observed for this N+-modified G-quadruplex (TG4T)4. These properties encouraged us to evaluate the N

Synthesis and physicochemical evaluation of fluorinated lipopeptide precursors of ligands for microbubble targeting

• Masayori Hagimori,
• Estefanía E. Mendoza-Ortega and
• Marie Pierre Krafft

Beilstein J. Org. Chem. 2021, 17, 511–518, doi:10.3762/bjoc.17.45

• peptide ligands dramatically increased cellular association in HER2-positive cells. Other lipids grafted to the RGD peptide and SG spacer were integrated in PEGylated liposomes and were efficiently associated with integrin αvβ3-expressing Colon-26 cells [25]. One of our general objectives is to synthesize

¹⁹F NMR as a tool in chemical biology

• Diana Gimenez,
• Aoife Phelan,
• Cormac D. Murphy and
• Steven L. Cobb

Beilstein J. Org. Chem. 2021, 17, 293–318, doi:10.3762/bjoc.17.28

• thermodynamic equilibrium binding constants (K) and kinetic rates of association (kon) and dissociation (koff) in protein–ligand binding events [37]. In order to achieve this, they analysed the binding of four different proline-rich peptides to a 5-FTrp-labelled Src homology 3 (SH3) recognition protein domain

Multiswitchable photoacid–hydroxyflavylium–polyelectrolyte nano-assemblies

• Alexander Zika and
• Franziska Gröhn

Beilstein J. Org. Chem. 2021, 17, 166–185, doi:10.3762/bjoc.17.17

• pH-responsive nano-assemblies with switchable size and structure are formed by the association of a photoacid, anthocyanidin, and a linear polyelectrolyte in aqueous solution. Specifically, anionic disulfonated naphthol derivatives, neutral hydroxyflavylium, and cationic poly(allylamine) are used as

• addition of a fifth hydroxy group, more binding sites become available for the association with the poly(allylamine), leading to an increase in assembly size: More multivalent small molecules bind to the polyelectrolyte, interconnecting more polyelectrolyte molecules into larger aggregates. At the same

• . Thermodynamic analysis of the assembly process For understanding the differences of the assemblies, isothermal titration calorimetry (ITC) was performed to elucidate the thermodynamics and to gain insight into the building block interactions in the assembly process. Basically, ITC measures the association heat

Insight into functionalized-macrocycles-guided supramolecular photocatalysis

• Minzan Zuo,
• Krishnasamy Velmurugan,
• Kaiya Wang,
• Xueqi Tian and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15

• complexes (1:1, 2:1, 1:2, and 2:2). For the 1:1, 2:1, and 1:2 host–guest complexes, the thermodynamic association (Ka) and dissociation constants (Kd) for the reactive guests and photoproducts are crucial for the fundamental understanding of supramolecular noncovalent interactions [12][13]. In addition

• molecules can absorb light and transfer energy, making the assemblies an efficient light-harvesting system. The host–guest binding stoichiometry is 1:1, and the association constant (Ka) of WP5β-CAR was calculated to be (2.34 ± 2.06) × 105 M−1. This system can function as a photocatalyst for the reduction

Supramolecular polymers with reversed viscosity/temperature profile for application in motor oils

• Jan-Erik Ostwaldt,
• Christoph Hirschhäuser,
• Stefan K. Maier,
• Carsten Schmuck and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2021, 17, 105–114, doi:10.3762/bjoc.17.11

• VII system requires a BU with strong dimerization tendency and a LU with precoordinating properties. For our purpose, we initially employed the guanidiniocarbonyl pyrrole (GCP) motif as a binding unit [19]. The GCP unit is a self-complementary zwitterion, which forms dimers with high association

• seen as a neutral analogue of the GCP motif. Due to the missing ionic interactions, the self-association is weaker, but still sufficiently strong, in aprotic solvents such as chloroform (Ka > 106 M−1) [27]. As for the LU, we chose the 1,1’-binaphthyl-2,2’-diamine (BINAM) backbone. The attachment of the

Molecular basis for protein–protein interactions

• Brandon Charles Seychell and
• Tobias Beck

Beilstein J. Org. Chem. 2021, 17, 1–10, doi:10.3762/bjoc.17.1

• modelled by the McGhee–von Hippel model of nonspecific protein binding to a surface [86]. In this model, the association with nucleic acids, quantified by KNA, is dependent on the cooperativity coefficient ω, which is based on the protein–protein association constant. A ω value of 1 represents no

• that a nucleic acid scaffold aids the assembly by concentrating assembly units and providing additional association energy. Some viral capsids can self-assemble around other scaffolds that mimic the viral genome in charge and size [89] or can also assemble without any scaffold to form empty capsid

Chiral anion recognition using calix[4]arene-based ureido receptors in a 1,3-alternate conformation

• Tereza Horáčková,
• Jan Budka,
• Vaclav Eigner,
• Wen-Sheng Chung,
• Petra Cuřínová and
• Pavel Lhoták

Beilstein J. Org. Chem. 2020, 16, 2999–3007, doi:10.3762/bjoc.16.249

• dissolves all anionic species tested, (ii) prevents the receptor molecule from self-association, and (iii) reduces the complexation constants to values easily measurable by 1H NMR titrations. A solution of an anion was gradually added to a solution of 7 or 8 in DMSO-d6 to obtain various calixarene/anion

Construction of pillar[4]arene[1]quinone–1,10-dibromodecane pseudorotaxanes in solution and in the solid state

• Xinru Sheng,
• Errui Li and
• Feihe Huang

Beilstein J. Org. Chem. 2020, 16, 2954–2959, doi:10.3762/bjoc.16.245

• spectrometry results, we believed that the differences between the stoichiometric ratio of the complexation in the solid state and in solution could be owing to the competitive role of solvent molecules in the combination of H and G. The association constant (Ka) calculated by the nonlinear curve fitting

Controlled decomposition of SF₆ by electrochemical reduction

• Sébastien Bouvet,
• Bruce Pégot,
• Stéphane Sengmany,
• Erwan Le Gall,
• Eric Léonel,
• Anne-Marie Goncalves and
• Emmanuel Magnier

Beilstein J. Org. Chem. 2020, 16, 2948–2953, doi:10.3762/bjoc.16.244

• disappearance of SF6 after 6 hours as well as all the fluorinated organic compounds. The only peak detected by 19F NMR is around −153 ppm. This value corresponds to the classical chemical shift range of a fluoride anion. Due to its broad appearance, we can postulate the association with cations coming from the