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

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

• partially due to the fact that the π–π-stacking of pyridines [50] was a competing interaction. The most probable rupture force, used in the KBE model, was due to the coordination complexes. Methods using the whole data set are strongly influenced by the stacking interaction and would have needed heavily

First principle investigation of the linker length effects on the thermodynamics of divalent pseudorotaxanes

• Andreas J. Achazi,
• Doreen Mollenhauer and
• Beate Paulus

Beilstein J. Org. Chem. 2015, 11, 687–692, doi:10.3762/bjoc.11.78

• first principle calculations show clearly that this enhanced binding is due to electronic effects, namely the dispersion interaction of the two linkers. For the shortest linker this interaction results in a nearly ideal π–π stacking. For the two longer linkers ideal packing is not possible due to steric

• dispersive interaction of the linking unit (two phenyl rings and the linker), which in case of the n0 guest fits perfectly on top of the anthracene linker of the DiC8 host. The distance between the linker of the host and the linker of the n0 guest is around 3.7 Å, quite close to an ideal distance for the π–π

• stacking of two benzene rings. The n1 and n2 guest do not perfectly fit with the host (Figure 2). In the n1-case the linker is folded away from the anthracene bridge, and for the n2-case one phenyl ring is twisted away due to steric constraints. The Gibbs energy of association ΔG in the gas phase of the

Synthesis and characterization of pH responsive D-glucosamine based molecular gelators

• Navneet Goyal,
• Hari P. R. Mangunuru,
• Bargav Parikh,
• Sonu Shrestha and
• Guijun Wang

Beilstein J. Org. Chem. 2014, 10, 3111–3121, doi:10.3762/bjoc.10.328

• referred to as supramolecular gelators or molecular gelators. They can form reversible gels in organic solvents, aqueous mixtures, and water. The gelation process is completely driven by weak intermolecular forces such as hydrogen bonding, π–π stacking, hydrophobic forces, and van der Waals forces. The

A one-pot multistep cyclization yielding thiadiazoloimidazole derivatives

• Debabrata Samanta,
• Anup Rana,
• Jan W. Bats and
• Michael Schmittel

Beilstein J. Org. Chem. 2014, 10, 2989–2996, doi:10.3762/bjoc.10.317

• by multiple π–π stacking (slighly displaced) at a distance of 3.36−3.40 Å (Figure 1c) while the iminophenyl groups are connected by weak intermolecular C(phenyl)-H···π(phenyl) contacts. Moreover, Figure 1a shows that the structure is planar except for the phenyl ring attached to the N4 atom (C2–N4–C5

• –C6 = 49.0°). The phenyl ring attached to the N3 atom is nearly coplanar (C1–N3–C3–C4 = 2.5°) with the thiadiazole ring allowing additional delocalization. This coplanar arrangement might help for intercalation into biological molecules using e.g., π–π stacking, C–H···π or ion–dipole interactions

• –π stacking. To take the solvent into consideration, the thermochemical analyses were performed in dichloromethane using the COSMO model with gas phase optimized geometries. Originally, DMAP should be hydrogen bonded to both amide protons in complex 8 increasing the nucleophilicity of both N-centers

Solution processable diketopyrrolopyrrole (DPP) cored small molecules with BODIPY end groups as novel donors for organic solar cells

• Diego Cortizo-Lacalle,
• Calvyn T. Howells,
• Upendra K. Pandey,
• Joseph Cameron,
• Neil J. Findlay,
• Anto Regis Inigo,
• Tell Tuttle,
• Peter J. Skabara and
• Ifor D. W. Samuel

Beilstein J. Org. Chem. 2014, 10, 2683–2695, doi:10.3762/bjoc.10.283

• organic field-effect transistors [24][25]. The DPP-based conjugated polymers usually show good electron and hole mobility and promising PCE values in OPVs due to large intermolecular interactions through π–π stacking. Nguyen et al. have investigated the DPP core in small molecules for OPVs with excellent

Molecular recognition of AT-DNA sequences by the induced CD pattern of dibenzotetraaza[14]annulene (DBTAA)–adenine derivatives

• Marijana Radić Stojković,
• Marko Škugor,
• Łukasz Dudek,
• Jarosław Grolik,
• Julita Eilmes and
• Ivo Piantanida

Beilstein J. Org. Chem. 2014, 10, 2175–2185, doi:10.3762/bjoc.10.225

• stacked dimers within the DNA minor groove similar to the crystal structure of close analogue (Figure 4, right). Conversely, the AP5 and AP6 aliphatic linkers are long enough to allow self-folding and easy intramolecular π–π stacking of adenine with DBTAA (Figure 4, upper right). During the binding event

• left – note the stacking of DBTAA and adenine) and AP3 (lower left – note the short linker which does not allow for the stacking of DBTAA and adenine); (right) detail of three molecules packing in crystal by π–π stacking of parallel DBTAA rings with a distance of ca. 3 Å (see [13] and Figure 8 therein

Chiral phosphines in nucleophilic organocatalysis

• Yumei Xiao,
• Zhanhu Sun,
• Hongchao Guo and
• Ohyun Kwon

Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218