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

Synthesis of new p-tert-butylcalix[4]arene-based polyammonium triazolyl amphiphiles and their binding with nucleoside phosphates

• Vladimir A. Burilov,
• Guzaliya A. Fatikhova,
• Mariya N. Dokuchaeva,
• Ramil I. Nugmanov,
• Diana A. Mironova,
• Pavel V. Dorovatovskii,
• Victor N. Khrustalev,
• Svetlana E. Solovieva and
• Igor S. Antipin

Beilstein J. Org. Chem. 2018, 14, 1980–1993, doi:10.3762/bjoc.14.173

• nucleotides must possess selectivity towards these anions. From this point of view, nucleotide receptors based on polyammonium cations are of great demand because the electrostatic interactions of such polyammonium systems and negatively charged phosphates are strong. Hydrogen bonding [8] and π-stacking

• + represent the dye and calixarene ions, respectively. By increasing the concentration to values above the CAC complexes with 3:2 stoichiometry are observed. This indicates that the interaction of forming aggregates with EY relies on both electrostatic interactions with positively charged headgroups and

Design, synthesis and structure of novel G-2 melamine-based dendrimers incorporating 4-(n-octyloxy)aniline as a peripheral unit

• Cristina Morar,
• Pedro Lameiras,
• Attila Bende,
• Gabriel Katona,
• Emese Gál and
• Mircea Darabantu

Beilstein J. Org. Chem. 2018, 14, 1704–1722, doi:10.3762/bjoc.14.145

• , due to their electrostatic interactions (attractions vs repulsions) G-2 ionic dendrimers 7b, 8 and 9 (Figure 10) produced the most developed spherical nano-aggregates. The ionic relationships masked those deduced in covalent series, namely the π–π and π–H stacking and angular-propeller connectivity of

Natural and redesigned wasp venom peptides with selective antitumoral activity

• Marcelo D. T. Torres,
• Gislaine P. Andrade,
• Roseli H. Sato,
• Cibele N. Pedron,
• Tania M. Manieri,
• Giselle Cerchiaro,
• Anderson O. Ribeiro,
• Cesar de la Fuente-Nunez and
• Vani X. Oliveira Jr.

Beilstein J. Org. Chem. 2018, 14, 1693–1703, doi:10.3762/bjoc.14.144

• electrostatic interactions, after which they tend to adopt helical conformations, which causes cell membrane permeabilization or even membrane disruption that may lead to necrosis [33]. These peptides may also be internalized into the cell, leading to the disruption of the mitochondrial membrane and causing

Steric “attraction”: not by dispersion alone

• Ganna Gryn’ova and
• Clémence Corminboeuf

Beilstein J. Org. Chem. 2018, 14, 1482–1490, doi:10.3762/bjoc.14.125

• steric bulk. In the present work, we quantify this contribution for a diverse set of molecular cores, ranging from unsubstituted benzene and cyclohexane to their derivatives carrying tert-butyl, phenyl, cyclohexyl and adamantyl substituents. While the importance of electrostatic interactions in the

Oligonucleotide analogues with cationic backbone linkages

• Melissa Meng and
• Christian Ducho

Beilstein J. Org. Chem. 2018, 14, 1293–1308, doi:10.3762/bjoc.14.111

• range and its ability to form both intermolecular electrostatic interactions and hydrogen bonds [50]. Letsinger's aminoalkyl phosphoramidate modification was stereogenic at the phosphorus atom, thus leading to complex mixtures of diastereomeric oligomers (with the exception of the aforementioned related

An overview of recent advances in duplex DNA recognition by small molecules

• Sayantan Bhaduri,
• Nihar Ranjan and
• Dev P. Arya

Beilstein J. Org. Chem. 2018, 14, 1051–1086, doi:10.3762/bjoc.14.93

• –indole amide minor groove binders connected through alkyl or ethoxyethyl linkers were developed by Tecilla et al. [111]. The authors confirmed that these conjugates with tach units, either free or Zn(II)-complexed forms, bind strongly to the minor groove through electrostatic interactions with the

• , thereby reducing strength of electrostatic interactions between the ligands with DNA phosphate backbone [120]. Wilson et al. rationally designed benzimidazole derivatives by keeping pre-organized N-methylbenzimidazole (N-MeBI)-thiophene as central fragment (conjugates 55 and 56, Figure 10) in order to

Local energy decomposition analysis of hydrogen-bonded dimers within a domain-based pair natural orbital coupled cluster study

• Ahmet Altun,
• Frank Neese and
• Giovanni Bistoni

Beilstein J. Org. Chem. 2018, 14, 919–929, doi:10.3762/bjoc.14.79

• between the DFT-SAPT and DLPNO-CCSD(T) total interaction energies decreases with increasing intermolecular distance. A comparison of electrostatic interactions estimated by LED and DFT-SAPT is shown in the central panel of Figure 5. At the equilibrium geometry, the sum of Eelstat and (the only provides a

• previous sections, the geometric preparation, weak pairs, and perturbative triples do not contribute significantly to the relative stabilities of the different conformers. In all cases, the largest LED terms are electronic preparation and electrostatic interactions at the HF level. This is not surprising

• , considering the strong dipole moments of water and HF and in light of the fact that the electrostatic interaction is well described at the HF level, as shown in the previous section. Interestingly, Eelstat and ΔEe show similar trends, thus highlighting the importance of classical electrostatic interactions in

An uracil-linked hydroxyflavone probe for the recognition of ATP

• Márton Bojtár,
• Péter Zoltán Janzsó-Berend,
• Dávid Mester,
• Dóra Hessz,
• Mihály Kállay,
• Miklós Kubinyi and
• István Bitter

Beilstein J. Org. Chem. 2018, 14, 747–755, doi:10.3762/bjoc.14.63

• a uracil nucleobase to the known 4’-dimethylamino-hydroxyflavone fluorophore. Results: The complexation of this scaffold with ATP is already known. The complex is held together by stacking and electrostatic interactions. To achieve multi-point recognition, we designed the uracil-appended version of

• , 4’-dimethylaminohydroxyflavone) was utilized by Pivovarenko and co-workers in ATP sensing in aqueous solution and in mitochondria [34][44]. DMHF was found to form 1:1 and 1:2 complexes with ATP. The two components were held together by π-stacking and by electrostatic interactions of the positively

Fluorogenic PNA probes

• Tirayut Vilaivan

Beilstein J. Org. Chem. 2018, 14, 253–281, doi:10.3762/bjoc.14.17

• make a close contact. However, based on their detailed comparative studies between stemless PNA and DNA beacons, the Boston Probes group argued that the quenching was more likely due to hydrophobic and electrostatic interactions between the fluorophore and the quencher. Nevertheless, different

Polarization spectroscopy methods in the determination of interactions of small molecules with nucleic acids – tutorial

• Tamara Šmidlehner,
• Ivo Piantanida and
• Gennaro Pescitelli

Beilstein J. Org. Chem. 2018, 14, 84–105, doi:10.3762/bjoc.14.5

• surface through electrostatic interactions with the phosphate backbone. However, that is plausible only for highly positive-charged ligands (at least four net positive charges present). 3.3.4. Strong ICD (intensity of ICD band similar or stronger than the CD bands of DNA/RNA): Usually of positive sign

Position-dependent impact of hexafluoroleucine and trifluoroisoleucine on protease digestion

• Susanne Huhmann,
• Anne-Katrin Stegemann,
• Kristin Folmert,
• Damian Klemczak,
• Johann Moschner,
• Michelle Kube and
• Beate Koksch

Beilstein J. Org. Chem. 2017, 13, 2869–2882, doi:10.3762/bjoc.13.279

• strong, short C–F bonds and perturb the acidity and basicity of adjacent functional groups. Moreover, these changes may strongly influence hydrogen bonding and electrostatic interactions that are crucial for binding to receptors or, in context of protease stability, enzymes. Thus, when introduced in the

Binding abilities of polyaminocyclodextrins: polarimetric investigations and biological assays

• Marco Russo,
• Daniele La Corte,
• Annalisa Pisciotta,
• Serena Riela,
• Rosa Alduina and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2017, 13, 2751–2763, doi:10.3762/bjoc.13.271

• binding efficiencies towards pDNA can be easily explained considering that, due to its peculiar conformation, the closer disposition of the negatively charged phosphate groups enables an optimization of the electrostatic interactions with the cationic AmCD. It is also reasonable to assume that the

Binding abilities of a chiral calix[4]resorcinarene: a polarimetric investigation on a complex case of study

• Marco Russo and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2017, 13, 2698–2709, doi:10.3762/bjoc.13.268

• observed of purely aliphatic cations; ii) non-specific electrostatic interactions, as accounted for by the lack of inclusion of anions. Furthermore, at least in the case of the p-nitroaniline derivatives, the aliphatic moiety of the guest interacts with the prolinylmethyl groups at the host rim, affecting

What contributes to an effective mannose recognition domain?

• Christoph P. Sager,
• Deniz Eriş,
• Martin Smieško,
• Rachel Hevey and
• Beat Ernst

Beilstein J. Org. Chem. 2017, 13, 2584–2595, doi:10.3762/bjoc.13.255

• ). With the entropically driven sLex interaction, surface waters are displaced to the bulk and penalized by a positive enthalpy term resulting from a desolvation penalty that is not compensated by the newly formed electrostatic interactions (Figure 6) [67]. According to Dunitz [68], the entropy that can

• desolvation are often neglected. Because of the large number of hydroxy groups present in carbohydrate ligands, and the polar amino acid side chains of the lectin binding sites, desolvation generates an essential enthalpic penalty which can hardly be compensated for by the newly formed electrostatic

• interactions [60]. Cabani et al. calculated that the desolvation of an isolated hydroxy group causes an enthalpic penalty of ΔH = 35 kJ/mol, which is slightly reduced by a beneficial entropic term of ΔS = 10 kJ/mol due to the release of solvating water molecules into bulk [61]. As a result, the desolvation

p-tert-Butylthiacalix[4]arenes functionalized by N-(4’-nitrophenyl)acetamide and N,N-diethylacetamide fragments: synthesis and binding of anionic guests

• Alena A. Vavilova and
• Ivan I. Stoikov

Beilstein J. Org. Chem. 2017, 13, 1940–1949, doi:10.3762/bjoc.13.188

• anions are larger in size than cations and therefore have a smaller charge in relation to their radius. It means that the electrostatic interactions for anions binding are weaker than for cations. Anions have various shape and geometry, and the design of receptors that are complementary to a specific