Biochemistry of fluoroprolines: the prospect of making fluorine a bioelement

• Vladimir Kubyshkin,
• Rebecca Davis and
• Nediljko Budisa

Beilstein J. Org. Chem. 2021, 17, 439–460, doi:10.3762/bjoc.17.40

• extensive documentation of the electrostatic interactions within the molecules and the observed conformational biases [145

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

• not rely on specific binding motifs. Here, electrostatic self-assembly was shown to yield a variety of supramolecular nanostructures [4][26][27][28][29][30][31][32][33]. We have built the nanoscale assemblies from polyelectrolytes and multiply oppositely charged molecules based on electrostatic

• interactions and secondary interactions such as π–π stacking [34][35][36][37][38][39][40]. The size and shape could be tuned through the free energy and the enthalpy/entropy interplay in the assembly process, which again are encoded in the molecular building block structure [31][37]. Supramolecular structures

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

• selectively obtained over the conventional 9,10:9',10'-cyclodimers by the supramolecular photocyclodimerization of 2-anthracenecarboxylate (AC) with the aid of β-CD-functionalized cationic derivatives as chiral catalysts (Figure 7) [25]. Due to the electrostatic interactions between cationic CD and anionic AC

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

• an electrostatic interaction between two molecules at 10 Å is around 1 kJ/mol, which is much higher than any other force at such a distance [47]. Long-range electrostatic interactions are affected by the net charges of the protein, i.e., proteins with a different net charge are electrostatically

• , it has been shown that the CCMV capsid formation is driven by electrostatic interactions governed by the pH value and the ionic strength [93]. Here, the positive N terminus of the assembly unit interacts with the negatively charged scaffold and drives the self-assembly process [94]. The advent of

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

• anions is becoming more and more significant [12][13][14]. There are many strategies aiming at anion recognition in the literature. Most of the receptors, however, rely on electrostatic interactions. These systems are represented by positively charged molecules, such as quaternary N-, S-, and P

Using multiple self-sorting for switching functions in discrete multicomponent systems

• Amit Ghosh and
• Michael Schmittel

Beilstein J. Org. Chem. 2020, 16, 2831–2853, doi:10.3762/bjoc.16.233

• undemanding building blocks. The plethora of self-sorting systems depends on either the geometric fit of their global shapes and/or matching of their local interactions. Various noncovalent interactions, such as H‐bonding [8][9], metal–ligand coordination [10][11][12][13], electrostatic interactions [14], π

Selective recognition of ATP by multivalent nano-assemblies of bisimidazolium amphiphiles through “turn-on” fluorescence response

• Rakesh Biswas,
• Surya Ghosh,
• Shubhra Kanti Bhaumik and
• Supratim Banerjee

Beilstein J. Org. Chem. 2020, 16, 2728–2738, doi:10.3762/bjoc.16.223

• . One of the challenges in the bio-anion detection is that the sensory probes have to be effective under physiological conditions. The highly polar nature of the aqueous media considerably weakens supramolecular interactions such as H-bonding and electrostatic interactions and as a result, it is in

• the nucleotides occurring through multivalent electrostatic interactions in the cavity/cleft created by the spatial orientation of the imidazolium groups. We herein consider a self-assembly based approach in which amphiphilic monomers with bisimidazolium moieties are utilized to create multivalent

• ) and ADP (50 µM), these values were 4.8 and 1.87, respectively (Figure 4b). Practically no increments were observed for AMP (50 µM) and Pi (50 µM) (Supporting Information File 1, Figure S11a and Figure 4b). As the multivalent binding is predominantly through electrostatic interactions, it was not

Thermodynamic and electrochemical study of tailor-made crown ethers for redox-switchable (pseudo)rotaxanes

• Henrik Hupatz,
• Marius Gaedke,
• Hendrik V. Schröder,
• Julia Beerhues,
• Arto Valkonen,
• Fabian Klautzsch,
• Sebastian Müller,
• Felix Witte,
• Kari Rissanen,
• Biprajit Sarkar and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2020, 16, 2576–2588, doi:10.3762/bjoc.16.209

• strong electrostatic interactions to ammonium ions and act as strong, competitive hydrogen-bond acceptors [57]. The high anodic shifts indicate strong attractive interactions between the wheels and axles, which compete with the coordination of the crown ether moiety. Thus, the secondary ammonium axles

NMR Spectroscopy of supramolecular chemistry on protein surfaces

• Peter Bayer,
• Anja Matena and
• Christine Beuck

Beilstein J. Org. Chem. 2020, 16, 2505–2522, doi:10.3762/bjoc.16.203

• ligands as well, thus altering their electrostatic interactions. Around the isoelectric point, where a molecule is neutral, hydrophobic interactions become more pronounced, which can lead to formation of soluble aggregates or even precipitation. Co-solvents such as DMSO-d6 are popular as solvents for more

• docking that the Cyt c/porphyrin complexes exist as a dynamic ensemble where multiple surface patches can transiently interact with the ligand through a combination of hydrophobic interactions with the porphyrin core and electrostatic interactions with the carboxylate substituents. Cucurbit[7]uril and

Design and synthesis of a bis-macrocyclic host and guests as building blocks for small molecular knots

• Elizabeth A. Margolis,
• Rebecca J. Keyes,
• Stephen D. Lockey IV and
• Edward E. Fenlon

Beilstein J. Org. Chem. 2020, 16, 2314–2321, doi:10.3762/bjoc.16.192

• molecular knots. The modular second-generation approach to small trefoil knots described herein involves electrostatic interactions between an electron-rich bis-macrocyclic host compound and electron-deficient guests in the threading step. The bis-macrocyclic host was synthesized in eight steps and 6.6

Naphthalene diimide bis-guanidinio-carbonyl-pyrrole as a pH-switchable threading DNA intercalator

• Poulami Jana,
• Filip Šupljika,
• Carsten Schmuck and
• Ivo Piantanida

Beilstein J. Org. Chem. 2020, 16, 2201–2211, doi:10.3762/bjoc.16.185

• pronounced aggregation, which could be attributed to the electrostatic interactions of the highly positively charged molecules along the negatively charged DNA/RNA backbone aided by the strong hydrophobic effect of the central NDI core. This effect yielded a marked ds-DNA condensation ability of compound 4

pH- and concentration-dependent supramolecular self-assembly of a naturally occurring octapeptide

• Goutam Ghosh and
• Gustavo Fernández

Beilstein J. Org. Chem. 2020, 16, 2017–2025, doi:10.3762/bjoc.16.168

• secondary structures, which lead to nanostructured materials [16][17]. Noncovalent interactions, such as hydrogen bonding, van der Waals interactions, hydrophobic interactions, electrostatic interactions, and π–π interactions [18][19][20][21][22] are common driving forces in peptide self-assembly. These

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

• heterogeneous photocatalysis is immobilising a molecular photocatalyst to a solid support. Most materials have inherent surface functionalities or can be modified to act as supports through covalent or electrostatic interactions, presenting a plethora of strategies to immobilise any photocatalyst with a

Bacterial terpene biosynthesis: challenges and opportunities for pathway engineering

• Eric J. N. Helfrich,
• Geng-Min Lin,
• Christopher A. Voigt and
• Jon Clardy

Beilstein J. Org. Chem. 2019, 15, 2889–2906, doi:10.3762/bjoc.15.283

• electrostatic interactions [54]. Moreover, TCs also assist intramolecular atom transfer and rearrangements including hydride or proton transfer and carbon shifts [10]. Eventually, the carbocation is quenched by deprotonation (E1-like) or nucleophilic attack (SN1-like) of water [45]. In contrast to

A combinatorial approach to improving the performance of azoarene photoswitches

• Joaquin Calbo,
• Aditya R. Thawani,
• Rosina S. L. Gibson,
• Andrew J. P. White and
• Matthew J. Fuchter

Beilstein J. Org. Chem. 2019, 15, 2753–2764, doi:10.3762/bjoc.15.266

• noncovalent forces are also predicted in the twisted Z-isomers of the 4pzMe-X family, for which θ remains approximately constant. Furthermore, the atomic charge of fluorine is calculated to be ca. −0.30e, which allows for electrostatic interactions with positively charged C atoms (ca. +0.40e) of the pyrazole

• ring in both 4pzH-X and 4pzMe-X families (Figure S7, Supporting Information File 1). These favorable dispersion and electrostatic interactions stabilize the Z-isomer ground state compared to the corresponding transition state, which in part explains the increase in energy barriers and in turn half

Anion-driven encapsulation of cationic guests inside pyridine[4]arene dimers

• Anniina Kiesilä,
• Jani O. Moilanen,
• Anneli Kruve,
• Christoph A. Schalley,
• Perdita Barran and
• Elina Kalenius

Beilstein J. Org. Chem. 2019, 15, 2486–2492, doi:10.3762/bjoc.15.241

• "through-wall" electrostatic interactions. Results and Discussion We have previously shown that tetraisobutylpyridine[4]arene forms hydrogen-bonded dimers with eight intermolecular N–H···O(amide) hydrogen bonds in the solid state, in solution and in the gas phase [11]. Resorcinarene capsules of similar

• anion driven at least to some extent. The reduced electron density in the pyridine rings is compensated by favorable "through-wall" electrostatic interactions between the exo-anion(s) and the endo-cation. In solution, by 1H NMR, complexation of Me4N+ cation was observed with 2, but not with 1 (Figures

Small anion-assisted electrochemical potential splitting in a new series of bistriarylamine derivatives: organic mixed valency across a urea bridge and zwitterionization

• Keishiro Tahara,
• Tetsufumi Nakakita,
• Alyona A. Starikova,
• Takashi Ikeda,
• Masaaki Abe and
• Jun-ichi Kikuchi

Beilstein J. Org. Chem. 2019, 15, 2277–2286, doi:10.3762/bjoc.15.220

• effects were previously reported for bis(NAr3) derivatives having π-conjugated bridges [8][9]. Judging from the long N···N distances (e.g., 13.16 Å for 1b+) in the DFT-optimized structure (Figure S5 in Supporting Information File 1), the through-space electrostatic interactions between the NAr3 units

• of larger counteranions increase because they do not form strong ion-pairs with charged species, enhancing electrostatic interactions between redox components [46][47][48][49][50][51][52]. Thus, a different mechanism is proposed to explain the present effects of the supporting electrolytes in terms

• maps of 1b+ (Figure 3, bottom). From these regions, 1b+ can form electrostatic interactions with negatively charged species. Indeed, an optimized structure of a complex of 1b+ and PF6− was obtained and featured an intermolecular H-bonding between the N–H proton and the F atom of hexafluorophosphate

1,2,3-Triazolium macrocycles in supramolecular chemistry

• Mastaneh Safarnejad Shad,
• Pulikkal Veettil Santhini and
• Wim Dehaen

Beilstein J. Org. Chem. 2019, 15, 2142–2155, doi:10.3762/bjoc.15.211

• interactions such as hydrogen bonding, π–π stacking, electrostatic interactions, van der Waals forces, hydrophobic/solvatophobic effects and coordination bonds [2][3]. Advances in supramolecules from molecular to macroscopic size with pre-structured or functionalized receptors and multivalent binding positions

• analysis which gives information about solution anion binding trends, the authors found that the cavity size of macrocycle, solvent effects and strength of electrostatic interactions notably affect the observed anion recognition processes [52]. 2.6.1. 1,2,3-Triazolium macrocycles with additional H-bond

• fundamental hydrogen bonding and electrostatic interactions related to the individual recognition motifs [53]. Another cyclophane macrocycle containing two 1,2,3-triazolium moieties was synthesized by Alcalde and co-workers in a moderate yield [54]. The anion-binding behavior of receptor 11 (Figure 10) was

Complexation of chiral amines by resorcin[4]arene sulfonic acids in polar media – circular dichroism and diffusion studies of chirality transfer and solvent dependence

• Bartosz Setner and
• Agnieszka Szumna

Beilstein J. Org. Chem. 2019, 15, 1913–1924, doi:10.3762/bjoc.15.187

• chemistry. In the present study we demonstrate that resorcin[4]arene sulfonic acid (RSA) interacts with chiral amines (amino acid derivatives and aminocavitands) to form inclusion complexes and capsules based on electrostatic interactions. The complexes were characterized by circular dichroism and DOSY NMR

• chiral multidentate amino compounds (Figure 1) in polar media (DMSO, methanol, aqueous media). RSA 1 features a hydrophobic cavity and a polar rim of sulfonic acid groups capable of forming electrostatic interactions. We will put a particular emphasis on ordering during complex formation that is

• capable of forming electrostatic interactions. However, in CSAs polar groups are positioned directly on a macrocyclic scaffold, while for RSAs at conformationally labile methylene linkers. Therefore, we think that RSAs are more adaptable than CSAs and are able to enclose guest molecules more tightly (by

2,3-Dibutoxynaphthalene-based tetralactam macrocycles for recognizing precious metal chloride complexes

• Li-Li Wang,
• Yi-Kuan Tu,
• Huan Yao and
• Wei Jiang

Beilstein J. Org. Chem. 2019, 15, 1460–1467, doi:10.3762/bjoc.15.146

• the shrunken cavity caused by intramolecular hydrogen bonds in the latter tetralactam macrocycle. The binding of the isophthalamide-based macrocycle is mainly driven by hydrogen bonds and electrostatic interactions. This naphthalene-based macrocycle has similar binding affinities to all the three

• conformers are possible. As shown in Figure 5a, AuCl4− can be well accommodated in the cavity of 1. AuCl4− is sandwiched by the two 2,3-dibutoxynaphthalene moieties, and the electron-poor gold centre of AuCl4− may interact with the electron-rich naphthalenes through electrostatic interactions. In addition

• with 2,6-pyridine dicarboxamide bridging units cannot. This may be due to the shrunken cavity caused by intramolecular hydrogen bonds in the latter tetralactam macrocycle. The binding driving forces of the isophthalamide-based macrocycle are mainly from hydrogen bonds and electrostatic interactions

Polyaminoazide mixtures for the synthesis of pH-responsive calixarene nanosponges

• Antonella Di Vincenzo,
• Antonio Palumbo Piccionello,
• Alberto Spinella,
• Delia Chillura Martino,
• Marco Russo and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2019, 15, 633–641, doi:10.3762/bjoc.15.59

• importance of electrostatic interactions in the sequestration process. In fact, anions 11–14 are sequestered nearly quantitatively from solution. By contrast, cationic 15 is absorbed much less effectively and, as expected, binding is favored under the most alkaline pH conditions. Conclusion In the present

Adhesion, forces and the stability of interfaces

• Robin Guttmann,
• Johannes Hoja,
• Christoph Lechner,
• Reinhard J. Maurer and
• Alexander F. Sax

Beilstein J. Org. Chem. 2019, 15, 106–129, doi:10.3762/bjoc.15.12

• interactions were nearly exclusively attributed to electrostatic interactions. We discuss the importance of dispersion interactions for the stabilization in systems that are traditionally explained in terms of the “special interactions” mentioned above. System stabilization can be explained by using

• more than a dispersion-dominated WMI. On the other hand, electrostatic interactions are often ignored, unless the interacting molecules have obvious dipolar structures. For example, the fact that there is electrostatic interaction between the quadrupoles of benzene molecules is mostly ignored or not

• quantities, and one cannot infer from tabulated dipole–dipole polarizabilities whether or not the higher short-range interactions are important or not. As for electrostatic interactions, the induction energy at short distances between the multipoles is in error for point-multipoles, but can be corrected when

Synthesis, biophysical properties, and RNase H activity of 6’-difluoro[4.3.0]bicyclo-DNA

• Sibylle Frei,
• Adam K. Katolik and
• Christian J. Leumann

Beilstein J. Org. Chem. 2019, 15, 79–88, doi:10.3762/bjoc.15.9

• fluorine atom pointing into the minor groove. Conversely, in the Ara-FHNA, repulsive electrostatic interactions between the fluorine atom and the 4’-oxygen of the 3’-adjected nucleotide resulted in a partial unstacking of the nucleobases and a destabilizing effect upon duplex formation [26]. Also other

• . The reason for the destabilizing nature of the 6’-diF-bc4,3-T versus both complements might be found in repulsive electrostatic interactions between the fluorine atoms and the 5’-oxygen. In the case of multiple insertions it might be possible that these interactions might be reduced or maybe

• destabilization might be accounted to repulsive electrostatic interactions between the equatorial fluorine atom and the 5’-oxygen. CD spectroscopy of the duplexes disclosed that the helical structure of the modified oligonucleotides paired to complementary DNA was still of a B-type, whereas an intermediate A/B

6’-Fluoro[4.3.0]bicyclo nucleic acid: synthesis, biophysical properties and molecular dynamics simulations

• Sibylle Frei,
• Andrei Istrate and
• Christian J. Leumann

Beilstein J. Org. Chem. 2018, 14, 3088–3097, doi:10.3762/bjoc.14.288

• entropical stabilization of the duplex structure. The cyclohexene ring of the modified unit adopted either a twist-boat or a boat alignment in the fully modified strand of both duplex types. Consequently, the fluorine atom was arranged in a way that the repulsive electrostatic interactions with the C(5

• simulations revealed a very rigid bicyclic sugar system with a diminished conformational adaptability of the cyclohexene unit. Mainly this rigidity in combination with the repulsive electrostatic interactions of the fluorine atom and the C(5’) oxygen seem to be responsible for the duplex destabilization

Pathoblockers or antivirulence drugs as a new option for the treatment of bacterial infections

• Matthew B. Calvert,
• Varsha R. Jumde and
• Alexander Titz

Beilstein J. Org. Chem. 2018, 14, 2607–2617, doi:10.3762/bjoc.14.239

• interact with the tyrosine gate formed by Tyr48 and Tyr137 [15][16], as well as form hydrogen bonds and electrostatic interactions with the Arg98/Glu50 salt bridge of the protein. Taking this coordination geometry into consideration for further ligand optimization, it was found important to focus on the