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

• structure of the complex is similar to the DEHF∙ATP complex. However, an additional π-stacking interaction is formed between the adenine and the uracil groups creating a so-called “double-sandwich” structure. In the other case, the π–π interactions vanish and the complex is stabilized through the base-pair

Fluorescent nucleobase analogues for base–base FRET in nucleic acids: synthesis, photophysics and applications

• Mattias Bood,
• Sangamesh Sarangamath,
• Moa S. Wranne,
• Morten Grøtli and
• L. Marcus Wilhelmsson

Beilstein J. Org. Chem. 2018, 14, 114–129, doi:10.3762/bjoc.14.7

• wanted to use the aromatic ring system previously developed by Roth et al. [39] as a nucleobase analogue to furnish greater π–π interactions with the natural bases and possibly also to increased hydrophobic effects. A new strategy for the preparation of tC analogues was used, starting from 5-iodo or 5

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

• interactions, π–π interactions, desolvation effects and entropy-unfavorable conformational dynamic restraints. Polarimetry is confirmed as a very useful and versatile tool for the investigation of supramolecular interactions with chiral hosts, even in complex systems involving multiple equilibria. Keywords

• outlines an important role assumed by π–π interactions. In fact, the small aromatic imidazolium cation 5 is appreciably included into CAP−2, although with a relatively small binding constant (K = 250 ± 20 M−1; ΔΘ = −14.6 ± 0.4 deg dm−1 M−1). It is interesting to notice that significant affinity towards CAP

• −2 is also shown by neutral nitroaniline derivatives 8 and 10, providing further confirmation that π–π interactions play an important role. Nevertheless, it is also worth noting here that the importance of electrostatic effects has been already outlined by Schneider and Schneider [32], who examined

One-pot syntheses of blue-luminescent 4-aryl-1H-benzo[f]isoindole-1,3(2H)-diones by T3P^® activation of 3-arylpropiolic acids

• Melanie Denißen,
• Alexander Kraus,
• Guido J. Reiss and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2017, 13, 2340–2351, doi:10.3762/bjoc.13.231

• distance is 3.437(4) Å. Consequently, π–π interactions must be considered for this structure [51][52]. Bond lengths and angles of the reported crystal structures 4b, 5, and 6 are in the expected range. The tricyclic 1H-benzo[f]isoindole-1,3(2H)-dionyl moiety in 4b, 5 and the corresponding 3-imino-1-oxo-2,3

• 5 (left) and a centrosymmetric dimer formation by π–π interactions (right) (ellipsoids are drawn at the 40% probability level). The ORTEP-type plot of the asymmetric unit of the crystal structure 6 (top) and π-stacking interactions (bottom) (ellipsoids are drawn at the 40% probability level

Mechanochemical Knoevenagel condensation investigated in situ

• Sebastian Haferkamp,
• Franziska Fischer,
• Werner Kraus and
• Franziska Emmerling

Beilstein J. Org. Chem. 2017, 13, 2010–2014, doi:10.3762/bjoc.13.197

• interactions such as hydrogen bonds, halogen bonds, and π∙∙∙π interactions [16][17][18][19]. For example, Toda et al. reported yields of 97% for Aldol condensations in the absence of any solvents [20]. Kaupp et al. described the first Knoevenagel condensation in a ball mill [21]. Compared to conventional

Molecular recognition of N-acetyltryptophan enantiomers by β-cyclodextrin

• Spyros D. Chatziefthimiou,
• Mario Inclán,
• Petros Giastas,
• Athanasios Papakyriakou,
• Konstantina Yannakopoulou and
• Irene M. Mavridis

Beilstein J. Org. Chem. 2017, 13, 1572–1582, doi:10.3762/bjoc.13.157

• to the secondary hydroxy level, apparently in order to optimize the π···π interactions between the indole planes (Figure 2 and Figure 3, Table 1). The above suggest a tight fit of the guest inside the cavity. On the other hand, the aliphatic part of NAcTrp, positioned in the space between dimers

• stability of the complex (a) no strong π···π interactions at 3.5 Å can be established in the middle of the β-CD dimer as in L-NAcTrp (Figure 5); (b) the aliphatic moieties of β-CD–L-NAcPhe protruding from the primary sides between dimers do not interact directly or even indirectly via β-CD hydroxy groups

Correlation of surface pressure and hue of planarizable push–pull chromophores at the air/water interface

• Frederik Neuhaus,
• Fabio Zobi,
• Gerald Brezesinski,
• Marta Dal Molin,
• Stefan Matile and
• Andreas Zumbuehl

Beilstein J. Org. Chem. 2017, 13, 1099–1105, doi:10.3762/bjoc.13.109

• this same condensed phase for the remainder of the experiments. During the first compression, the film organized obviously into a condensed phase. Upon decompression, the monolayer remains in this condensed state due to strong π–π interactions. The following compression cycles reach the exact same

• Å2 is obtained, that mirrors the area per molecule at low surface pressure found in the Langmuir–Pockels experiments. The transition into the densely packed film due to strong π–π interactions around 15 mN/m leads to the smaller area per molecule. Grazing incidence X-ray diffraction (GIXD) The

• ordering phenomenon during the first compression can be explained by π–π interactions between the flipper mechanophores. We therefore characterized the degree of membrane ordering using synchrotron grazing incidence X-ray diffraction. The GIXD data in Supporting Information File 1 shows the absence of any

Interactions between shape-persistent macromolecules as probed by AFM

• Johanna Blass,
• Jessica Brunke,
• Franziska Emmerich,
• Cédric Przybylski,
• Vasil M. Garamus,
• Artem Feoktystov,
• Roland Bennewitz,
• Gerhard Wenz and
• Marcel Albrecht

Beilstein J. Org. Chem. 2017, 13, 938–951, doi:10.3762/bjoc.13.95

• polyconjugated polymers ranged from 6 to 16 nm, depending on the side groups and the method of determination [9][10][11]. Among many supramolecular interactions, such as hydrogen bonding, π–π-interactions or hydrophobic host–guest interactions [12][13][14][15][16], the interactions of cyclodextrins (CDs) with

Synthesis and properties of fluorescent 4′-azulenyl-functionalized 2,2′:6′,2″-terpyridines

• Adrian E. Ion,
• Liliana Cristian,
• Mariana Voicescu,
• Masroor Bangesh,
• Augustin M. Madalan,
• Daniela Bala,
• Constantin Mihailciuc and
• Simona Nica

Beilstein J. Org. Chem. 2016, 12, 1812–1825, doi:10.3762/bjoc.12.171

• terpyridine fragments are involved in π–π interactions (3.56–3.66 Å). The separation between the neighboring azulenyl moieties is higher than 3.85 Å. Photophysical properties The photophysical properties of the azulene-containing terpyridines, 4a and 4b have been investigated by absorption and emission

Experimental and theoretical insights in the alkene–arene intramolecular π-stacking interaction

• Valeria Corne,
• Ariel M. Sarotti,
• Carmen Ramirez de Arellano,
• Rolando A. Spanevello and
• Alejandra G. Suárez

Beilstein J. Org. Chem. 2016, 12, 1616–1623, doi:10.3762/bjoc.12.158

• additional effort to understand the extent to which the π–π interactions affect the conformational equilibriums of a system, we next explored the M06-2X/6-31+G(d) PES of acrylate 6d bearing a methoxymethyl group at the benzylic position of the molecule (Figure 5). With the lack of stabilizing π-stacking

Indenopyrans – synthesis and photoluminescence properties

• Andreea Petronela Diac,
• Ana-Maria Ţepeş,
• Albert Soran,
• Ion Grosu,
• Anamaria Terec,
• Jean Roncali and
• Elena Bogdan

Beilstein J. Org. Chem. 2016, 12, 825–834, doi:10.3762/bjoc.12.81

• interactions. Further edge-to-face H···π [44] and π–π interactions [45][46] (Table 4) between molecules from neighboring layers contribute to the three-dimensional crystal packing (Figure S6 in Supporting Information File 1). Conclusion Several indenopyrone derivatives were synthesized and characterized by NMR

• derivatives 2a–d and 3''b measured in acetonitrile and methylene chloride at rt. Absorption and emission data for dihydroindenopyrone derivatives 2'a–d, 2''b–d and 3''b. Intermolecular H···π and π–π interactions in the crystal of 6a. Supporting Information Supporting Information File 62: Experimental

Supramolecular structures based on regioisomers of cinnamyl-α-cyclodextrins – new media for capillary separation techniques

• Gabor Benkovics,
• Ondrej Hodek,
• Martina Havlikova,
• Zuzana Bosakova,
• Pavel Coufal,
• Milo Malanga,
• Eva Fenyvesi,
• Andras Darcsi,
• Szabolcs Beni and
• Jindrich Jindrich

Beilstein J. Org. Chem. 2016, 12, 97–109, doi:10.3762/bjoc.12.11

• complicated process and besides the host–guest interaction other additional intermolecular interactions may also take place. Due to the numerous hydroxy groups present in the studied molecules these secondary interactions most probably are the hydrogen-bond interactions between the CD units, or the π–π

• interactions of the cinnamyl moieties. The sum of all these possible interactions results in the large supramolecular aggregates observed by DLS. Effect of competitive additives on the aggregation behavior: DLS and ROESY experiments In order to demonstrate that in the case of the Cin-α-CD the main force which

Synthesis and photophysical characteristics of polyfluorene polyrotaxanes

• Aurica Farcas,
• Giulia Tregnago,
• Ana-Maria Resmerita,
• Pierre-Henri Aubert and
• Franco Cacialli

Beilstein J. Org. Chem. 2015, 11, 2677–2688, doi:10.3762/bjoc.11.288

• synthesis of 1·TM-βCD or 1·TM-γCD in polar protic solvents is driven by hydrophobic interactions in combination with electrostatic, van der Waals or π–π interactions. In comparison, in polar aprotic solvents such as DMF, THF relies mostly on host–guest specific interactions, such as dispersion or dipole

Friedel–Crafts-type reaction of pyrene with diethyl 1-(isothiocyanato)alkylphosphonates. Efficient synthesis of highly fluorescent diethyl 1-(pyrene-1-carboxamido)alkylphosphonates and 1-(pyrene-1-carboxamido)methylphosphonic acid

• Anna Wrona-Piotrowicz,
• Janusz Zakrzewski,
• Anna Gajda,
• Tadeusz Gajda,
• Anna Makal,
• Arnaud Brosseau and
• Rémi Métivier

Beilstein J. Org. Chem. 2015, 11, 2451–2458, doi:10.3762/bjoc.11.266

• from the adjacent strings along [100] take part in π···π interactions, also forming molecular dimers (Figure 7). The shortest C···C distances are C7–C15 and C5–C9 (3.367(2) Å, and 3.410(2) Å, respectively). The presence of π–π-bonded aggregates in the crystal structure of 3a is in line with the

Urethane tetrathiafulvalene derivatives: synthesis, self-assembly and electrochemical properties

• Xiang Sun,
• Guoqiao Lai,
• Zhifang Li,
• Yuwen Ma,
• Xiao Yuan,
• Yongjia Shen and
• Chengyun Wang

Beilstein J. Org. Chem. 2015, 11, 2343–2349, doi:10.3762/bjoc.11.255

• 294 nm and 315 nm (aggregated solid state). This was also observed for T2, which illustrated that π–π interactions and H-aggregation occurred with the increase in concentration [22][23][24]. To further study the driving forces for the self-assembly of T1 and T2, FTIR spectra were also measured (Figure

• C=O stretching vibration (around 1720 cm−1) suggested that strong hydrogen bonds between urethane groups were formed [25][26]. These results indicated that π–π interactions and hydrogen bonding were the main driving forces behind the self-assembly. In addition, UV−vis and FTIR spectra were measured

The simple production of nonsymmetric quaterpyridines through Kröhnke pyridine synthesis

• Isabelle Sasaki,
• Jean-Claude Daran and
• Gérard Commenges

Beilstein J. Org. Chem. 2015, 11, 1781–1785, doi:10.3762/bjoc.11.193

• -chair conformation. The packing is stabilised by van der Waals contacts and weak π–π interactions between symmetry related N2-C21-C22-C23-C24-C25 and N4-C41-C42-C43-C44-C45 pyridine rings (1+x, y, z) with a centroid-to-centroid distance of 3.761(2) Å, and an average interatomic distance between planes

Polythiophene and oligothiophene systems modified by TTF electroactive units for organic electronics

• Alexander L. Kanibolotsky,
• Neil J. Findlay and
• Peter J. Skabara

Beilstein J. Org. Chem. 2015, 11, 1749–1766, doi:10.3762/bjoc.11.191

• , with the optical band gap being in the range of 1.7–1.9 eV. When comparing the spectra in CH2Cl2 solutions to those of the solid film, the red shift in absorption is due to the emergence of π–π interactions in the solid state. Compared to the aforementioned polymers, poly(thienylenevinylene) (PTV) 39

Are D-manno-configured Amadori products ligands of the bacterial lectin FimH?

• Tobias-Elias Gloe,
• Insa Stamer,
• Cornelia Hojnik,
• Tanja M. Wrodnigg and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2015, 11, 1096–1104, doi:10.3762/bjoc.11.123

• (1). A somewhat weaker complexation is predicted for 9 and 10 than for 1. We had expected 10 to score clearly better than 9, owing to the possibility of π–π interactions between the phenyl substituent in 10 and the tyrosine gate at the entrance of the FimH CRD. However, this seems not to be the case

• Amadori products are tilted in comparison to MeMan and somewhat lifted from the binding site (Figure 3B and C). When the respective anomeric centres are taken as a reference, 9 is lifted by 0.5 Å and 10 by 0.7 Å in comparison with complexed MeMan. The tilting effect apparently also prevents effective π–π

• interactions between the FimH tyrosine gate and Amadori product 10. The effect of tilting of Amadori products 9 and 10 upon FimH complexation can also be analyzed by comparison of hydrogen bonding in the complex. Close inspection of the H-bond network reveals that the average length of H-bonds established with

Glycoluril–tetrathiafulvalene molecular clips: on the influence of electronic and spatial properties for binding neutral accepting guests

• Yoann Cotelle,
• Marie Hardouin-Lerouge,
• Stéphanie Legoupy,
• Olivier Alévêque,
• Eric Levillain and
• Piétrick Hudhomme

Beilstein J. Org. Chem. 2015, 11, 1023–1036, doi:10.3762/bjoc.11.115

• recognition of aromatic guest molecules through π–π interactions [16][17]. We recently described various glycoluril-based molecular clips 1–4 [18][19] (Figure 1) for which the structure varies by: i) the nature of connection between the glycoluril spacer and the TTF sidewalls, ii) the nature of the peripheral

Copper ion salts of arylthiotetrathiafulvalenes: synthesis, structure diversity and magnetic properties

• Longfei Ma,
• Jibin Sun,
• Xiaofeng Lu,
• Shangxi Zhang,
• Hui Qi,
• Lei Liu,
• Yongliang Shao and
• Xiangfeng Shao

Beilstein J. Org. Chem. 2015, 11, 850–859, doi:10.3762/bjoc.11.95

• discussed in the crystal structure section. On the other hand, the antiferromagnetic interaction of radical cations in 7·CuBr2 could be due to the π–π interactions, because the neighbouring donor molecules have a S···S contact (3.30 Å) along the a-axis. Figure 6a shows the magnetic susceptibility of 1·CuBr4

Mechanical stability of bivalent transition metal complexes analyzed by single-molecule force spectroscopy

• Manuel Gensler,
• Christian Eidamshaus,
• Maurice Taszarek,
• Hans-Ulrich Reissig and
• Jürgen P. Rabe

Beilstein J. Org. Chem. 2015, 11, 817–827, doi:10.3762/bjoc.11.91

• UPy dimers (DDAA–AADD pairs) in hexadecane. The UPy dimers exhibit shorter rupture lengths of 0.20 nm compared to 0.29 nm, resulting in much higher rupture forces from 150 to 250 pN compared to 50–100 pN for UAT dimers. Another model system probing π–π-interactions associated with van-der-Waals forces

Trifluoromethyl-substituted tetrathiafulvalenes

• Olivier Jeannin,
• Frédéric Barrière and
• Marc Fourmigué

Beilstein J. Org. Chem. 2015, 11, 647–658, doi:10.3762/bjoc.11.73

• comparison, in the neutral donor molecule 1c, the folding angles amount to 20.59(5) and 19.00(5)° respectively [31]. Such π–π interactions have been shown to derive from quadrupolar interactions between the π systems of both donor and acceptor moieties [47], and their geometrical characteristics to favor the

Highly selective generation of vanillin by anodic degradation of lignin: a combined approach of electrochemistry and product isolation by adsorption

• Dominik Schmitt,
• Carolin Regenbrecht,
• Marius Hartmer,
• Florian Stecker and
• Siegfried R. Waldvogel

Beilstein J. Org. Chem. 2015, 11, 473–480, doi:10.3762/bjoc.11.53

• polymeric backbone has a very important influence on the adsorption behavior (Figure 7). The polystyrene backbones appear to be especially well suited for the adsorption of 1 from alkaline solutions. This can be explained by attractive π–π interactions between the backbone and the adsorptive phase. All

Molecular ordering at electrified interfaces: Template and potential effects

• Thanh Hai Phan and
• Klaus Wandelt

Beilstein J. Org. Chem. 2014, 10, 2243–2254, doi:10.3762/bjoc.10.233

• and the benzyl groups. In addition π–π-interactions between all π-systems of adjacent molecules will play a role with the stipulation that the benzyl groups take up a trans-conformation [6] as shown in Figure 2 and Figure 8b and in the structural models in Figure 11. In particular, the π–π

• interactions between neighboring monocation radicals are important which, by spin-pairing, are known to lead to the formation of dimers in solution [5]. The adsorbate–substrate interactions are obviously dominated by electrostatic interactions between the doubly (DBV2+) or singly (DBV+•) charged bipyridinium

Scalable synthesis of 5,11-diethynylated indeno[1,2-b]fluorene-6,12-diones and exploration of their solid state packing

• Bradley D. Rose,
• Peter J. Santa Maria,
• Aaron G. Fix,
• Chris L. Vonnegut,
• Lev N. Zakharov,
• Sean R. Parkin and
• Michael M. Haley

Beilstein J. Org. Chem. 2014, 10, 2122–2130, doi:10.3762/bjoc.10.219

• )°, giving a variant of the common herringbone motif, despite the lack of a crystallographic glide plane. In addition to the IF-dione π-stacking, inversion-related phenyl groups on the solubilizing groups are paired by π–π interactions. The stacking in compounds 8c and 8d (Si(n-Pr)3 and Si(iPr)3, vol. ~278