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

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

• optimized geometries are presented in Figure 2. The investigation of the DEHF∙ATP 1:1 complex revealed a sandwich structure, which is held together by a π–π stacking- and an H-bond interaction. The triphosphate group is positioned near ring C of the DEHF and the π-stacking occurs between the adenine group

Recent advances on organic blue thermally activated delayed fluorescence (TADF) emitters for organic light-emitting diodes (OLEDs)

• Thanh-Tuân Bui,
• Fabrice Goubard,
• Malika Ibrahim-Ouali,
• Didier Gigmes and
• Frédéric Dumur

Beilstein J. Org. Chem. 2018, 14, 282–308, doi:10.3762/bjoc.14.18

• luminance of 100 cd/m2, slightly red-shifted compared to the emission observed for doped OLEDs. Clearly, the specific design of D6 and its highly twisted structure efficiently weakened the π–π-stacking interactions, providing a general design rule for the elaboration of TADF emitters insensitive to the

Complexation of molecular clips containing fragments of diphenylglycoluril and benzocrown ethers with paraquat and its derivatives

• Leonid S. Kikot',
• Catherine Yu. Kulygina,
• Alexander Yu. Lyapunov,
• Svetlana V. Shishkina,
• Roman I. Zubatyuk,
• Tatiana Yu. Bogaschenko and
• Tatiana I. Kirichenko

Beilstein J. Org. Chem. 2017, 13, 2056–2067, doi:10.3762/bjoc.13.203

• π–π stacking and C–H∙∙∙X (X = N, O, F ...) interactions. The stability of inclusion complexes based on molecular clips and paraquat derivatives depends on two factors: 1) the value of the positive charge on the dipyridinium fragment of paraquat derivatives, the distribution of which is well

• paraquat, the following moieties may be involved: the glycoluril fragment (hydrogen bonds involving the oxygen atoms of the carbonyl groups), the catechol part of the crown ether fragments (π–π stacking interactions) and the polyether chains of benzocrown ethers (C–H···О interactions). The first two

• complexation constant of the clip 6 with paraquat (7), which was: lgK = 1.46 ± 0.01 (−ΔG = 1.96 ± 0.02 kcal/mol). The complex of clip 6 with paraquat (7) may be stabilized through π–π stacking interactions of the electron-deficient aromatic rings of paraquat and the electron donating veratrol fragments of the

Mechanochemical synthesis of small organic molecules

• Tapas Kumar Achar,
• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2017, 13, 1907–1931, doi:10.3762/bjoc.13.186

• solvent-free mechanomilling [50]. By varying the electron density on the aromatic aldehydes, it was observed that electron deficient aldehydes provided a better yield with excellent stereo selectivity over electron rich systems. The observed result suggests that a π–π stacking interaction between electron

Sugar-based micro/mesoporous hypercross-linked polymers with in situ embedded silver nanoparticles for catalytic reduction

• Qing Yin,
• Qi Chen,
• Li-Can Lu and
• Bao-Hang Han

Beilstein J. Org. Chem. 2017, 13, 1212–1221, doi:10.3762/bjoc.13.120

• described as the Langmuir–Freundlich isotherm [47]. The polymer matrix has higher adsorption capacity for 4-NP due to π–π stacking interactions, which can encourage 4-NP molecules to enter the polymer channel to form the adsorbed species [54]. At the same time, the hydrogen atom is introduced onto the

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

• change is significant and represents the expected red shift. Although contributions from changes in π–π stacking on spectroscopic properties cannot be excluded, the observed red shift in compressed flipper monolayers is consistent with the earlier experiments on the planarization of monomeric flipper

Fluorescent carbon dots from mono- and polysaccharides: synthesis, properties and applications

• Stephen Hill and
• M. Carmen Galan

Beilstein J. Org. Chem. 2017, 13, 675–693, doi:10.3762/bjoc.13.67

• interaction between the positively charged amino group in DOX and the negatively charged groups on the CD surface can take place. Also van der Waals and π–π stacking interactions were attributed as contributing factors to the DOX loading and DOX incorporation into the hollow CD cavity. Drug release at acidic

A new class of organogelators based on triphenylmethyl derivatives of primary alcohols: hydrophobic interactions alone can mediate gelation

• Wangkhem P. Singh and
• Rajkumar S. Singh

Beilstein J. Org. Chem. 2017, 13, 138–149, doi:10.3762/bjoc.13.17

• geometry (unlike the planar geometry of say anthracene, pyrene, etc.), π–π stacking will be favoured only between benzene units of different trityl groups. A small library of triphenylmethyl derivatives was synthesized from the corresponding primary alcohols employing a single step reaction and detailed

• planar two-dimensional structures will be similar to the width of TPM-G12 (8.50 Å). The observed d-spacing value of 8.12 Å from powder XRD experiment correlates closely with this value. The weak intensity peak at 22.02° (4.10 Å) may result from π–π stacking between benzene rings of adjacent

• linear molecular arrays and also between two-dimensional planar arrays. The weak intensity peak at 22.39° (3.96 Å) can be attributed to the presence of π–π stacking between benzene rings of adjacent triphenylmethyl groups. Dye absorption studies Dyes are commercially important and are widely used in many

Supramolecular frameworks based on [60]fullerene hexakisadducts

• Andreas Kraft,
• Johannes Stangl,
• Ana-Maria Krause,
• Klaus Müller-Buschbaum and
• Florian Beuerle

Beilstein J. Org. Chem. 2017, 13, 1–9, doi:10.3762/bjoc.13.1

• ][34][35][36][37][38][39][40][41][42][43][44][45] or π–π-stacking [46] that retain porosity in the solid state under activation conditions have been reported so far. One possible way to enhance stability and shape-persistency might be the implementation of polyfunctional building blocks in order to

Synthesis of spiro[isoindole-1,5’-isoxazolidin]-3(2H)-ones as potential inhibitors of the MDM2-p53 interaction

• Salvatore V. Giofrè,
• Santa Cirmi,
• Raffaella Mancuso,
• Francesco Nicolò,
• Giuseppe Lanza,
• Laura Legnani,
• Agata Campisi,
• Maria A. Chiacchio,
• Michele Navarra,
• Bartolo Gabriele and
• Roberto Romeo

Beilstein J. Org. Chem. 2016, 12, 2793–2807, doi:10.3762/bjoc.12.278

• 180° rotation of the isoindolinone core such that the benzyl group and dialkylamide occupy the Leu26 and Phe19 pockets, respectively. The reoriented binding mode, similar to the MI63 analogue, takes advantage of the π–π stacking interaction with His96 of MDM2 and the benzyl moiety of compound 6e, and

Effects of solvent additive on “s-shaped” curves in solution-processed small molecule solar cells

• John A. Love,
• Shu-Hua Chou,
• Ye Huang,
• Guilllermo C. Bazan and
• Thuc-Quyen Nguyen

Beilstein J. Org. Chem. 2016, 12, 2543–2555, doi:10.3762/bjoc.12.249

• reflection, suggesting a quite well-ordered film. Additionally, there is a small peak at 1.79 Å−1, corresponding to a spacing of 3.5 Å, which we attribute to π–π stacking. There is a broad feature centered at Q = 1.5 Å−1 which is seen in both films and at all orientations, which is the convolution of two

A self-assembled cyclodextrin nanocarrier for photoreactive squaraine

• Ulrike Kauscher and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2016, 12, 2535–2542, doi:10.3762/bjoc.12.248

• inclusion between the adamantane groups and the cyclodextrin cavities at the surface of cyclodextrin vesicles (CDVs) results in efficient immobilization of the squaraine on a nanocarrier. In addition, π–π stacking (and hence inactivation) of the squaraine is supressed due to the steric separation of the

• . In a first set of experiments, we investigated the photochemical properties of AdSq in acetonitrile (Figure 2). The absorption spectrum shows a peak at 665 nm indicative of the presence of squaraine monomers in the solution. A shoulder around 610 nm indicates aggregation of the squaraine due to π–π

• stacking. A comparison of absorption spectra in different solvents revealed that the amount of aggregation is rather low in acetonitrile or ethanol but increases dramatically if water is used as a solvent (see Figure S1 in Supporting Information File 1). This is in agreement with literature and highlights

High performance p-type molecular electron donors for OPV applications via alkylthiophene catenation chromophore extension

• Paul B. Geraghty,
• Calvin Lee,
• Jegadesan Subbiah,
• Wallace W. H. Wong,
• James L. Banal,
• Mohammed A. Jameel,
• Trevor A. Smith and
• David J. Jones

Beilstein J. Org. Chem. 2016, 12, 2298–2314, doi:10.3762/bjoc.12.223

• evident (Figure 5a). However, λmax is dependent on the degree of formation of π–π stacking and development of the lowest energy transition with two clear sharp peaks at 552 nm and 590 nm (λmax) for BMR, while for BPR λmax is at 594 nm with a shoulder at around 630 nm indicating poor formation of the

• cm−2. BPR shows promise with a high FF (74%), however a lower Voc (0.82 V) and a reduced Jsc (14.3 mA cm−2) reduce the PCE to 8.7%. UV–vis data indicate that under these SVA conditions the π–π stacking is not fully developed indicating that optimizing SVA conditions may lead to improved light

• architecture described above. The collected device data are summarized in Table 5, and the J–V curves are shown in Figure 13. Examination of the BTxR UV–vis data for as-cast films (Figure 5d) indicates that BT8R does not have a well-developed π–π stacking peak in as-cast films, unlike BTR. Also, both BT4R and

Synthesis and characterization of fluorinated azadipyrromethene complexes as acceptors for organic photovoltaics

• Forrest S. Etheridge,
• Roshan J. Fernando,
• Sandra Pejić,
• Matthias Zeller and
• Geneviève Sauvé

Beilstein J. Org. Chem. 2016, 12, 1925–1938, doi:10.3762/bjoc.12.182

• structure is distorted tetrahedral with favorable π–π stacking distances between the proximal phenyl and pyrrole rings of the two separate ligands (Figure 10a and 10b). The distance between centroids is 3.56 Å for Zn(L2)2, compared to 3.63 Å for Zn(ADP)2 [38]. The shorter distance found for Zn(L2)2 suggests

• a stronger interaction between the proximal phenyl and pyrrole rings than in Zn(ADP)2. Unfortunately, it cannot be determined whether the addition of fluorine or phenylacetylene contributed to the shorter π–π stacking distances without a crystal structure for Zn(WS3)2. Intermolecular favorable π–π

• stacking distances are observed between the pyrrolic phenylacetylene arms of two chelates seen on the outside of the unit cell, as well as between the distal phenyl rings of two chelates. Due to the crowded packing and difficulty in obtaining a clear image to convey these observations, the authors invite

From supramolecular chemistry to the nucleosome: studies in biomolecular recognition

• Marcey L. Waters

Beilstein J. Org. Chem. 2016, 12, 1863–1869, doi:10.3762/bjoc.12.175

• -helices; aromatic interactions; β-hairpin peptides; cation–π interactions; dynamic combinatorial chemistry; histone; molecular recognition in water; nucleosome; π–π-stacking; post-translational modification; supramolecular chemistry; Review Childhood influences When thinking about how to start writing

• postdoc. Seminal work probing the electrostatic component of π–π stacking and edge-face aromatic interactions as well as cation–π interactions was being published at the time, as well as tantalizing suggestions about their relevance in biological structure and function. In particular, I was inspired by

• -Sanders Model for π–π stacking from 1990 [4]. (d) Kool’s nonpolar isostere of thymidine from 1995 [5].(e) Gellman’s model for π–π stacking in aqueous solution [6]. (a) Model β-hairpin for investigation of aromatic interactions. (b) Examples of noncovalent interactions studied, from weakest to strongest

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

• supramolecular interactions are observed in the crystal packing, via the azulene moieties and the terpyridine groups. In the crystal of 4a, the molecules are organized in columns running along the crystallographic a axis by π–π stacking interactions (3.39–3.64 Å). In the neighboring columns the molecular units

• structures, different twisting was observed that might be responsible for the observed fluorescent profile. The solid-state crystal packing showed π–π stacking interactions between the pyridine rings in face-to-face or T-shape orientation, completed by slipped-off π–π stacked azulenyl moieties according to

• ; found: C, 83.4; H, 5.2; N, 10.8; MS (ESI+, m/z): 402 (100, MH+), 403 (30%). Molecular structure and numbering scheme of 4′-(1-azulenyl)-2,2′:6′,2″-terpyridine (4a, left) and 4′-(1-(4,6,8-trimethyl-azulenyl)-2,2′:6′,2″-terpyridine (4b, right). Packing diagram for 4a showing the π–π stacking and CH–π

Effect of the π-conjugation length on the properties and photovoltaic performance of A–π–D–π–A type oligothiophenes with a 4,8-bis(thienyl)benzo[1,2-b:4,5-b′]dithiophene core

• Ni Yin,
• Lilei Wang,
• Yi Lin,
• Jinduo Yi,
• Lingpeng Yan,
• Junyan Dou,
• Hai-Bo Yang,
• Xin Zhao and
• Chang-Qi Ma

Beilstein J. Org. Chem. 2016, 12, 1788–1797, doi:10.3762/bjoc.12.169

• oligothiophene chains. In the solid state, absorption spectra of these compounds (see Figure 1b) are remarkably broadened and red-shifted relative to those in solutions, which is attributable to strong π–π stacking interaction between the molecular backbones in the solid films [31][32]. It is noticeable that

Synthesis and characterization of benzodithiophene and benzotriazole-based polymers for photovoltaic applications

• Desta Gedefaw,
• Marta Tessarolo,
• Margherita Bolognesi,
• Mario Prosa,
• Renee Kroon,
• Wenliu Zhuang,
• Patrik Henriksson,
• Kim Bini,
• Ergang Wang,
• Michele Muccini,
• Mirko Seri and
• Mats R. Andersson

Beilstein J. Org. Chem. 2016, 12, 1629–1637, doi:10.3762/bjoc.12.160

• interchain π–π stacking, BDT is a widely used electron-rich monomer. Moreover, alkyl or aryl groups can easily be introduced to BDT basic units as side groups to finely tune the properties of the resulting polymers, not only in terms of solubility but also contributing, for example, to extend the π

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

• driving forces for self-assembly of TTF derivatives were mainly hydrogen bond interactions and π–π stacking interactions. The electronic conductivity of the T1 and T2 films was tested by a four-probe method. Keywords: hydrogen bond; nanoribbon; self-assembly; tetrathiafulvalene; urethane; Introduction

• nanomaterials is generally accepted to be the self-assembly of supermolecules, which is constructed through weak noncovalent interactions such as π–π stacking, van der Waals interactions, charge transfer and H-bonding interactions [3][4][5][6]. Generally speaking, H-bonding interactions are the key

• units and urethane groups (Figure 1). The combination of the urethane group (forming hydrogen bonds) and the TTF unit (forming π–π stacking) may promote the formation of nanostructures. To the best of our knowledge, urethane groups have been rarely introduced into the molecular structure of TTF

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

• dimensionality of charge carrier transport [1] by involving π–π stacking interactions. Varying the substituents of the conjugated backbone allows control over the polymer’s effective conjugation length and electronic properties, whilst also influencing the extent of inter-chain interactions. Two of the most

• the preparation of TTF mixed valance state materials, which showed superconducting properties [25]. Fusing the TTF unit with dithiin rings in bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) led to the extension of 1D π–π stacking intermolecular interactions in a donor sheet of a mixed valance state

• -acceptor into the conjugated backbone led to a polymer with a narrow optical band gap (Egopt = 1.32 eV in CH2Cl2 solution), with the expected lower value of Egopt = 1.26 eV in the film due to π–π stacking interactions. The value of the HOMO/LUMO levels (−5.13/−3.49 eV) in the film were noticeably different

Star-shaped tetrathiafulvalene oligomers towards the construction of conducting supramolecular assembly

• Masahiko Iyoda and
• Masashi Hasegawa

Beilstein J. Org. Chem. 2015, 11, 1596–1613, doi:10.3762/bjoc.11.175

• interactions between molecules having one or more unpaired electrons [3][4], neutral TTF and its derivatives also easily form stacked columnar structures with face-to-face π···π stacking and side-by-side S···S interactions in the crystalline state. Furthermore, weak intermolecular interactions (hydrogen

• bonding, metal coordination, CT interaction, π···π stacking, van der Waals interaction, etc.) play an important role in the formation of the three-dimensional (3D) crystal structures [5]. For the construction of nanostructured objects, π···π, S···S, and other weak intermolecular interactions first

• formed by casting a solution of 48 on a glass surface (Figure 17c). XRD studies on the fiber and the film of 48 revealed that the fiber has a hexagonal alignment, whereas the film has a lamellar structure with lateral order and π···π stacking. It is worth noting that the film of 48 prepared by casting a

Thiazole-induced rigidification in substituted dithieno-tetrathiafulvalene: the effect of planarisation on charge transport properties

• Rupert G. D. Taylor,
• Joseph Cameron,
• Iain A. Wright,
• Neil Thomson,
• Olena Avramchenko,
• Alexander L. Kanibolotsky,
• Anto R. Inigo,
• Tell Tuttle and
• Peter J. Skabara

Beilstein J. Org. Chem. 2015, 11, 1148–1154, doi:10.3762/bjoc.11.129

• resolved but there is a non-resolved peak caused by overlap of the cathodic peaks on the reverse scan. Compound 2 appears to show a first oxidation wave at 0.09 V, however, this is an artefact due to a minor degree of aggregation induced by π–π stacking between some of the molecules. This is followed by

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

• ]. Obviously, FimH binds α-D-mannosides such as simple methyl α-D-mannoside (MeMan, 1) but not β-mannosides. Mannosides with an aromatic aglycone, such as p-nitrophenyl α-D-mannoside (pNPMan) and 4-methylumbelliferyl α-D-mannoside (3) show an improved affinity to FimH due to π–π-stacking interactions of the

Synthesis of photoresponsive cholesterol-based azobenzene organogels: dependence on different spacer lengths

• Yuchun Ren,
• Bin Wang and
• Xiuqing Zhang

Beilstein J. Org. Chem. 2015, 11, 1089–1095, doi:10.3762/bjoc.11.122

• ], etc. The driving force for the spontaneous formation of gel could be relatively non-covalent interactions such as π–π stacking [4][5][6][7], hydrogen bonding [7][8][9], dipole–dipole [10], and van der Waals interactions [11][12]. A series of cholesterol-based gelators were reported [13][14][15]. These