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

Anion–π catalysis on carbon allotropes

• M. Ángeles Gutiérrez López,
• Mei-Ling Tan,
• Giacomo Renno,
• Augustina Jozeliūnaitė,
• J. Jonathan Nué-Martinez,
• Javier Lopez-Andarias,
• Naomi Sakai and
• Stefan Matile

Beilstein J. Org. Chem. 2023, 19, 1881–1894, doi:10.3762/bjoc.19.140

• macrodipoles. (C–E) Anion–π catalysis on (C) C60 fullerenes 1, (D) SWCNTs 2 and (E) MWCNTs 3. Part E of Figure 1 was adapted from [44] (© 2023 M. A. Gutiérrez López et al., published by the American Association for the Advancement of Science, distributed under the terms of the Creative Commons Attribution 4.0

• cyclization of 68 at positive (XVIII), zero (XVII) and negative voltage (XIX). Parts B and C of Figure 9 were adapted from [44] (© 2023 M. A. Gutiérrez López et al., published by the American Association for the Advancement of Science, distributed under the terms of the Creative Commons Attribution 4.0

• graphite 76. Figure 10 was adapted from [44] (© 2023 M. A. Gutiérrez López et al., published by the American Association for the Advancement of Science, distributed under the terms of the Creative Commons Attribution 4.0 International License, https://creativecommons.org/licenses/by/4.0). Acknowledgements

Tying a knot between crown ethers and porphyrins

• Maksym Matviyishyn and
• Bartosz Szyszko

Beilstein J. Org. Chem. 2023, 19, 1630–1650, doi:10.3762/bjoc.19.120

• sodium(I), zinc(II), magnesium(II), and barium(II) [106][107][108][109]. Association constants of the reported host–guest complexes showed similar values to those of diazacrown ethers [110][111]. Johnston and Gunter presented a crown ether-capped porphyrin receptor 10, which showed unexpected binding

Complexes of resorcin[4]arene with secondary amines: synthesis, solvent influence on “in-out” structure, and theoretical calculations of non-covalent interactions

• Waldemar Iwanek

Beilstein J. Org. Chem. 2023, 19, 1525–1536, doi:10.3762/bjoc.19.109

• role in their self-association and the formation of larger supramolecular structures such as dimers [3], hexamers [4][5], octamers [6], and nano-aggregates [7]. The stability of these structures is highly reliant on the type of solvent used. Most of the works are studies of non-polar environments such

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

CO₂ complexation with cyclodextrins

• Cecilie Høgfeldt Jessen,
• Jesper Bendix,
• Theis Brock Nannestad,
• Heloisa Bordallo,
• Martin Jæger Pedersen,
• Christian Marcus Pedersen and
• Mikael Bols

Beilstein J. Org. Chem. 2023, 19, 1021–1027, doi:10.3762/bjoc.19.78

• association constants between CD’s and CO2. Samples were prepared that consisted of citrate-phosphate buffer (pH 3, 50 mM), 7 (40 μM) and a fixed concentration of cyclodextrin ([CD]o; 1–4 mM) and put into the pressure cell. The spectrum was recorded at 0, 2, 4 , 6 and/or 8 bar CO2 pressure over the liquid

A fluorescent probe for detection of Hg²⁺ ions constructed by tetramethyl cucurbit[6]uril and 1,2-bis(4-pyridyl)ethene

• Xiaoqian Chen,
• Naqin Yang,
• Yue Ma,
• Xinan Yang and
• Peihua Ma

Beilstein J. Org. Chem. 2023, 19, 864–872, doi:10.3762/bjoc.19.63

• that TMeQ[6] and G form an inclusion complex with a host–guest ratio of 1:1 and the equilibrium association constant (Ka) was 2.494 × 104 M−1. The G@TMeQ[6] fluorescent probe can sensitively recognize Hg2+ ions by fluorescence enhancement. The linear range is 0.33 × 10−5–1.65 × 10−5 mol·L−1, R2

• that a G and TMeQ[6] inclusion complex is formed with a 1:1 stoichiometry. Isothermal titration calorimetry (ITC) analysis The association constant and thermodynamic parameters of the host–guest interaction between G and TMeQ[6] can be obtained using ITC. At 25 °C, a neutral aqueous solution of TMeQ[6

• ] (1.0 × 10−4 mol·L−1, 1.00 mL) was gradually added to the aqueous solution of G, and the exothermic isotherms (Figure S1 in Supporting Information File 1) and thermodynamic data (Table 1) were obtained. The equilibrium association constant (Ka) of G and TMeQ[6] is 2.494 × 104 M−1, ΔH = −88.43 kJ/mol

Direct C2–H alkylation of indoles driven by the photochemical activity of halogen-bonded complexes

• Martina Mamone,
• Giuseppe Gentile,
• Jacopo Dosso,
• Maurizio Prato and
• Giacomo Filippini

Beilstein J. Org. Chem. 2023, 19, 575–581, doi:10.3762/bjoc.19.42

• absorption spectra recorded in acetonitrile in 1 cm path quartz cuvettes. [DABCO]: 0.5 M; [2a]: 0.5 M. 1H NMR titration of DABCO in a solution of 2a in ACN-d3 to detect their halogen-bonding association through the shift of the signal of Hα. Proposed reaction mechanism for the photochemical alkylation of 1a

Phenanthridine–pyrene conjugates as fluorescent probes for DNA/RNA and an inactive mutant of dipeptidyl peptidase enzyme

• Josipa Matić,
• Tana Tandarić,
• Marijana Radić Stojković,
• Filip Šupljika,
• Zrinka Karačić,
• Ana Tomašić Paić,
• Lucija Horvat,
• Robert Vianello and
• Lidija-Marija Tumir

Beilstein J. Org. Chem. 2023, 19, 550–565, doi:10.3762/bjoc.19.40

• ), spectral changes could be attributed to a single dominant binding mode. Titration data were processed by the Scatchard equation [38][39] and Global Fit procedure [40] to calculate the association constants and ratio n [bound compound]/[polynucleotide] (Table 2, Figure 4 and Figures S15–S18, Supporting

• increased upon addition of the enzyme (Figure 6), suggesting the important role of the hydrophobic pyrene subunit for protein binding [18]. Association constant and thermodynamical binding parameters were additionally determined by ITC titrations [17]. The resulting titration data were fitted to a single

• is entropically driven, which is generally related to the release of water molecules from the protein to the bulk water [43][44]. The association constants obtained by different methods slightly differ because the measurements were made in a different concentration range. It also can be assumed that

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

• substituents on the nitrogens and sterically more hindered tricyclic adducts. Mechanistically, the authors proposed the reaction begins with a transmetalation of 2-cyanophenylboronic acid with the Rh(I) species resulting in 143. Upon association of 143 with the diazabicyclic alkene 132a a syn exo-addition

• salicylaldehydes with EWGs failed to react. The authors hypothesized the reaction mechanism begins with the association of the Rh(III) catalyst with the hydroxy group of salicylaldehyde (151a) resulting in a selective cleavage of the aldehyde C–H bond producing the rhodocycle 153 which side-on coordinates with the

Discrimination of β-cyclodextrin/hazelnut (Corylus avellana L.) oil/flavonoid glycoside and flavonolignan ternary complexes by Fourier-transform infrared spectroscopy coupled with principal component analysis

• Nicoleta G. Hădărugă,
• Gabriela Popescu,
• Dina Gligor (Pane),
• Cristina L. Mitroi,
• Sorin M. Stanciu and
• Daniel Ioan Hădărugă

Beilstein J. Org. Chem. 2023, 19, 380–398, doi:10.3762/bjoc.19.30

• for preparation. On the other hand, similar methods such as spray-drying do not provide intimate contact between the three types of components for a sufficient period of time to reach the association–dissociation equilibrium [1][27][67]. In this study, the recovery yields were in the range of 51.5

Recommendations for performing measurements of apparent equilibrium constants of enzyme-catalyzed reactions and for reporting the results of these measurements

• Robert N. Goldberg,
• Robert T. Giessmann,
• Peter J. Halling,
• Carsten Kettner and
• Hans V. Westerhoff

Beilstein J. Org. Chem. 2023, 19, 303–316, doi:10.3762/bjoc.19.26

• sight. Corresponding to a single biochemical reaction, there could be a large number of chemical reaction equations, one for each combination of the chemical species involved in the system of reactions and in any possible association state with H+, Mg2+ and Ca2+. An example of the distinction between a

• The choice of the chemical reference reaction out of the set of chemical reactions connected by H+, Mg2+ or Ca2+ association or dissociation reactions, is arbitrary. If possible, it is recommended that this calculation of K and ΔrH° be performed from K′ and ΔrH′°, respectively, even if the focus lies

Synthesis, α-mannosidase inhibition studies and molecular modeling of 1,4-imino-ᴅ-lyxitols and their C-5-altered N-arylalkyl derivatives

• Martin Kalník,
• Sergej Šesták,
• Juraj Kóňa,
• Maroš Bella and
• Monika Poláková

Beilstein J. Org. Chem. 2023, 19, 282–293, doi:10.3762/bjoc.19.24

• Martin Kalnik Sergej Sestak Juraj Kona Maros Bella Monika Polakova Institute of Chemistry, Center for Glycomics, Slovak Academy of Sciences, Dúbravská cesta 9, 845 38 Bratislava, Slovakia Medical Vision, Civic Research Association, Záhradnícka 4837/55, 82108 Bratislava, Slovakia 10.3762/bjoc

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

• dressings. This saponin possesses two large hydrophilic parts, surrounding the aglycone [30]. The association chitosan–saponin can show other functions for medicinal purposes, and anticancer nanoparticles made of chitosan loaded with saponins have been prepared by Nair and Jayakumar [31], and even

• matrices, or, in this case, associated to the new hydrophobic regions provided by saponin. When this concentration is higher, the association of 1-N appears to create aggregates, saturating the cyclodextrin sites but allowing the polysaccharide networks affect the sorption. When saponin is introduced, this

Inclusion complexes of the steroid hormones 17β-estradiol and progesterone with β- and γ-cyclodextrin hosts: syntheses, X-ray structures, thermal analyses and API solubility enhancements

• Alexios I. Vicatos,
• Zakiena Hoossen and
• Mino R. Caira

Beilstein J. Org. Chem. 2022, 18, 1749–1762, doi:10.3762/bjoc.18.184

• formation, complex structure, stoichiometry and association constants via the detection and measurement of small deviations in the 1H NMR chemical shifts for both host and guest molecules upon complexation. PXRD studies were generally used to detect the formation of new crystalline phases following attempts

• . Furthermore, no previous structure determinations via SCXRD analysis of CD complexes of BES and PRO have been reported. Many studies involved phase solubility analyses to determine CD complex formation and association constants. Our previous study of the complexation of the steroidal anticancer agent 2

Navigating and expanding the roadmap of natural product genome mining tools

• Friederike Biermann,
• Sebastian L. Wenski and
• Eric J. N. Helfrich

Beilstein J. Org. Chem. 2022, 18, 1656–1671, doi:10.3762/bjoc.18.178

• Biodiversity Genomics (LOEWE TBG) and the German Chemical Industry Association. FB acknowledges funding from a Kekulé Fellowship of the German Chemical Industry Association.

New azodyrecins identified by a genome mining-directed reactivity-based screening

• Atina Rizkiya Choirunnisa,
• Kuga Arima,
• Yo Abe,
• Noritaka Kagaya,
• Kei Kudo,
• Hikaru Suenaga,
• Junko Hashimoto,
• Manabu Fujie,
• Noriyuki Satoh,
• Kazuo Shin-ya,
• Kenichi Matsuda and
• Toshiyuki Wakimoto

Beilstein J. Org. Chem. 2022, 18, 1017–1025, doi:10.3762/bjoc.18.102

• Atina Rizkiya Choirunnisa Kuga Arima Yo Abe Noritaka Kagaya Kei Kudo Hikaru Suenaga Junko Hashimoto Manabu Fujie Noriyuki Satoh Kazuo Shin-ya Kenichi Matsuda Toshiyuki Wakimoto Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan Technology Research Association for Next