Synthesis and herbicidal activities of aryloxyacetic acid derivatives as HPPD inhibitors

• Man-Man Wang,
• Hao Huang,
• Lei Shu,
• Jian-Min Liu,
• Jian-Qiu Zhang,
• Yi-Le Yan and
• Da-Yong Zhang

Beilstein J. Org. Chem. 2020, 16, 233–247, doi:10.3762/bjoc.16.25

• -dicarbonyl bidentate chelation with the active center metal, and 2) through favorable sandwich π–π stacking interactions between aromatic rings and the Phe360, Phe403 residues of the active site. Thus, 1,3-dicarbonyl and aromatic moieties are indispensable pharmacophores for potent HPPD-inhibiting compounds

The use of isoxazoline and isoxazole scaffolding in the design of novel thiourea and amide liquid-crystalline compounds

• Itamar L. Gonçalves,
• Rafaela R. da Rosa,
• Vera L. Eifler-Lima and
• Aloir A. Merlo

Beilstein J. Org. Chem. 2020, 16, 175–184, doi:10.3762/bjoc.16.20

• , intensity, resolution and peaks of some phase transitions are lost. Considering that molecules self-organize upon cooling, first by hydrogen bonds followed by π-stacking and van der Waals forces, DSC scanning at 10 °C/min is too fast to allow the molecules to self-assemble in a perfect 3D matrix. Even with

Reversible photoswitching of the DNA-binding properties of styrylquinolizinium derivatives through photochromic [2 + 2] cycloaddition and cycloreversion

• Sarah Kölsch,
• Heiko Ihmels,
• Jochen Mattay,
• Norbert Sewald and
• Brian O. Patrick

Beilstein J. Org. Chem. 2020, 16, 111–124, doi:10.3762/bjoc.16.13

• aggregates in the solid state and even in solution through dipole–dipole interactions and directional π stacking (Scheme 2), as observed, for example, with donor-substituted benzoquinolizinium derivatives [79] or donor-substituted styrylpyridinium derivatives [80][81][82]. Hence, an ideal overlap of the π

Influence of the cis/trans configuration on the supramolecular aggregation of aryltriazoles

• Sara Tejera,
• Giada Caniglia,
• Rosa L. Dorta,
• Andrea Favero,
• Javier González-Platas and
• Jesús T. Vázquez

Beilstein J. Org. Chem. 2019, 15, 2881–2888, doi:10.3762/bjoc.15.282

• as between the triazole rings, and therefore the presence of multiple intermolecular π–π stacking and π–bromine [19] interactions. This compound precipitated in the presence of any amount of water and gelled only in DMSO at a low temperature. Compound 10 produced pseudo-crystals in DMSO/H2O (1:1, v/v

• ) and its X-ray analysis was not accurate enough to resolve its structure. However, its crystal packing (Figure 5) deserves discussion. As with compound 12, this packing revealed a number of π–bromine interactions [19], together with a high degree of π–π stacking interactions between the aromatic rings

• configuration through X-ray diffraction studies can be considered good approximations to the supramolecular structure of aryltriazoles in gels. Thus, these compounds showed a high degree of parallelism between the phenyltriazolyl rings, therefore revealing the presence of π–π stacking and π–bromine interactions

Acid-catalyzed rearrangements in arenes: interconversions in the quaterphenyl series

• Sarah L. Skraba-Joiner,
• Carter J. Holt and
• Richard P. Johnson

Beilstein J. Org. Chem. 2019, 15, 2655–2663, doi:10.3762/bjoc.15.258

• ) are narrowly clustered in a range of ca. 2 kcal/mol, with the lowest energy isomer predicted to be o,o'-quaterphenyl (17). This low ranking for the most congested isomer may be attributed to intramolecular π stacking. Very similar results were obtained with M06-2X/6-311+G(d,p) theory, which also

Reversible switching of arylazopyrazole within a metal–organic cage

• Anton I. Hanopolskyi,
• Soumen De,
• Michał J. Białek,
• Yael Diskin-Posner,
• Liat Avram,
• Moran Feller and
• Rafal Klajn

Beilstein J. Org. Chem. 2019, 15, 2398–2407, doi:10.3762/bjoc.15.232

• encapsulated two molecules of E-1 (in agreement with the NMR spectra), arranged in an antiparallel fashion (Figure 3). The binding of E-1 within 2 is driven by a combination of π–π stacking, van der Waals forces, and C–H···π interactions (vide infra); in addition, the encapsulation is likely facilitated by the

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

• macrocycle has been reported by Nakamura and his co-workers containing three 1,2,3-triazolium and carbazole moieties 12 (Figure 10). π–π stacking interactions and the self-association ability of the synthesized macrocycle are increased in comparison with its neutral analogue due to the decreased electron

Fluorinated azobenzenes as supramolecular halogen-bonding building blocks

• Esther Nieland,
• Oliver Weingart and
• Bernd M. Schmidt

Beilstein J. Org. Chem. 2019, 15, 2013–2019, doi:10.3762/bjoc.15.197

• , connected by C–H···F contacts. The azobenzenes A2 interact by lamellar 2D π-stacking, anthracene U1 interact predominantly by C–H···π interactions as both the solubilizing mesitylene group and the two perpendicular lutidine acceptors effectively prevent stacking of the anthracenes body (Supporting

Complexation of 2,6-helic[6]arene and its derivatives with 1,1′-dimethyl-4,4′-bipyridinium salts and protonated 4,4'-bipyridinium salts: an acid–base controllable complexation

• Jing Li,
• Qiang Shi,
• Ying Han and
• Chuan-Feng Chen

Beilstein J. Org. Chem. 2019, 15, 1795–1804, doi:10.3762/bjoc.15.173

• broadened peaks, which indicated that π–π stacking interactions between the bipyridinium unit of G4 and the benzene ring of the hosts might exist. The signals for protons 2 and 13 of H4 showed a downfield shift with broadened signals due to deshielding effect, while the signals for protons 11 and 12 showed

• protons of G1 and the aromatic rings of H1 with distances of 2.683 for A, 2.845 for B, 2.788 for C, 2.802 for D, and 2.868 Å for E, respectively. There also exist π–π stacking interactions between the pyridinium of G1 and the aromatic ring of H1 with the distance of 3.854 Å for F, a CH···O hydrogen bond

Functional panchromatic BODIPY dyes with near-infrared absorption: design, synthesis, characterization and use in dye-sensitized solar cells

• Quentin Huaulmé,
• Cyril Aumaitre,
• Outi Vilhelmiina Kontkanen,
• David Beljonne,
• Alexandra Sutter,
• Gilles Ulrich,
• Renaud Demadrille and
• Nicolas Leclerc

Beilstein J. Org. Chem. 2019, 15, 1758–1768, doi:10.3762/bjoc.15.169

• BOD-TTPA is observed from diluted solution to the anchored dye (see Figure 5a). Despite the same amount of CDCA in the dyeing solution (10 molar equivalents), this result suggests a higher tendency for π stacking interactions. Once anchored, BOD-TTPA exhibits consequently a broader absorption profile

Host–guest interactions in nor-seco-cucurbit[10]uril: novel guest-dependent molecular recognition and stereoisomerism

• Xiaodong Zhang,
• Wei Wu,
• Zhu Tao and
• Xin-Long Ni

Beilstein J. Org. Chem. 2019, 15, 1705–1711, doi:10.3762/bjoc.15.166

• encapsulation of this moiety. Pyrene group, that are too large for the individual CB[6]–CB[7] sized cavities of ns-CB[10] [23], it is thus believed that the upfield shift of the pyrene protons is attributed the intermolecular π–π stacking between the two pyrenyl moieties as proposed in the plausible inclusion

• , the fluorescence intensity of the G2 monomer emissions gradually decreased, while the maximum emission intensity at around 485 nm (typical excimer emissions of pyrene) increased. The excimer emission band of G2 can be attributed to the interaction of two pyrene units resulting in intermolecular π–π

• stacking, which was due to the two identical cavities of host-1. Consequently, the top–center isomerism of the G2·host-1 ternary complexes was conveniently confirmed from the optical signal after the changes in monomer/excimer fluorescence emissions of the pyrene groups on G2. Surprisingly, the

Synthesis, enantioseparation and photophysical properties of planar-chiral pillar[5]arene derivatives bearing fluorophore fragments

• Guojuan Li,
• Chunying Fan,
• Guo Cheng,
• Wanhua Wu and
• Cheng Yang

Beilstein J. Org. Chem. 2019, 15, 1601–1611, doi:10.3762/bjoc.15.164

• quantum yield was significantly decreased to 46.4% compared with 78.2% for Py-6. We ascribed the decreased fluorescence of P5A-Py to the π–π stacking of the Py units caused by the high local concentration of perylene. For P5A-DPA, which also bears two DPA units in one macrocyclic host, the fluorescent

• quantum yield was only slightly decreased. This should be mainly due to the steric hindrance of the 9- and 10-phenyl groups, which inhibited the π–π stacking of the anthracene core in DPA. The fluorescent lifetimes of P5A-Py and P5A-DPA were compared with Py-6 and DPA-6. As shown in Figure 2, the lifetime

• of P5A-Py is 3.4 ns which is shorter than that of Py-6 (4.4 ns), demonstrating that grafting two Py units in close proximity in one host, opened a new route for nonradiative decay. This phenomenon further verified the occurrence of π–π stacking of the Py fragments in P5A-Py. The lifetime of P5A-DPA

A heteroditopic macrocycle as organocatalytic nanoreactor for pyrroloacridinone synthesis in water

• Piyali Sarkar,
• Sayan Sarkar and
• Pradyut Ghosh

Beilstein J. Org. Chem. 2019, 15, 1505–1514, doi:10.3762/bjoc.15.152

• of macrocycles with multiple functional groups has been employed as alternative templates to induce the organic environment for catalysis via multiple weak interactions viz. π–π stacking, hydrogen bonding, etc. [25][26][27][28][29]. At the same time, several efforts have been made to develop

• aggregation tendency. Herein we have extensively explored a multifunctional macrocycle (BATA-MC), comprising bis-amide and tris-amine functionalities as H-bond donor/acceptor moieties, and parallel benzene moieties for aromatic π–π stacking interactions as an organocatalytic nanoreactor for organic

• observed an ESIMS peak at m/z 679.32 corresponding to [BATA-MC + 1a + H]+ (Supporting Information File 1, Figure S2) which supported the association of the macrocycle with isatin. Hence, further condensation between enaminoketone and isatin provides the intermediate B. The isatin moiety also has π-stacking

Selective detection of DABCO using a supramolecular interconversion as fluorescence reporter

• Indrajit Paul,
• Debabrata Samanta,
• Sudhakar Gaikwad and
• Michael Schmittel

Beilstein J. Org. Chem. 2019, 15, 1371–1378, doi:10.3762/bjoc.15.137

• repulsion. For instance, pyrazine creates notable repulsive interactions of the α-H towards the zinc porphyrin ring in a sandwich complex. Apparently, stability gains through π–π stacking in the sandwich with pyrene, coronene, etc. are not strong enough to compensate for the strain in [Cu2(1)(2)(guest)]2

Self-assembly behaviors of perylene- and naphthalene-crown macrocycle conjugates in aqueous medium

• Xin Shen,
• Bo Li,
• Tiezheng Pan,
• Jianfeng Wu,
• Yangxin Wang,
• Jie Shang,
• Yan Ge,
• Lin Jin and
• Zhenhui Qi

Beilstein J. Org. Chem. 2019, 15, 1203–1209, doi:10.3762/bjoc.15.117

• through hydrogen bonding and metal ion coordination in nonpolar solvents [66][67][68]. Compared with NDI, PDI has more aromatic rings to generate stronger intermolecular π−π stacking, leading to molecular aggregates more easily, and these aggregates or supramolecular assemblies can give rise to desirable

• in the above-tested five solvent systems were also recorded. Because of the relatively weaker π–π stacking effect of the NDI units comparing with PDI units, 2 has a better solubility in the organic solvents. Consequently, the UV–vis absorption bands of 2 in all the organic solvents can be clearly

• were investigated. As shown in Figure 2a, micelle-like assemblies of 1 were observed, while, because of the higher polarity of MeCN, the aggregation of 1 through π–π stacking was considerably enhanced forming linear assemblies (Figure 2b). Interestingly, when imposed to an aqueous medium through adding

Efficient synthesis of pyrazolopyridines containing a chromane backbone through domino reaction

• Razieh Navari,
• Saeed Balalaie,
• Saber Mehrparvar,
• Fatemeh Darvish,
• Frank Rominger,
• Fatima Hamdan and
• Sattar Mirzaie

Beilstein J. Org. Chem. 2019, 15, 874–880, doi:10.3762/bjoc.15.85

• of the product (Figure 2). Meanwhile, via hydrogen bridges and the solvent molecules (water and ethanol) the molecules build pairs with π–π stacking of the aromatic systems. To examine the scope and generality of our reaction, other (arylhydrazono)methyl-4H-chromen-4-ones were synthesized and their

Coordination chemistry and photoswitching of dinuclear macrocyclic cadmium-, nickel-, and zinc complexes containing azobenzene carboxylato co-ligands

• Jennifer Klose,
• Tobias Severin,
• Peter Hahn,
• Alexander Jeremies,
• Jens Bergmann,
• Daniel Fuhrmann,
• Jan Griebel,
• Bernd Abel and
• Berthold Kersting

Beilstein J. Org. Chem. 2019, 15, 840–851, doi:10.3762/bjoc.15.81

• lengths reveal no anomalies and are similar to those in [Zn2L(μ-OAc)]+. There are no π–π stacking interactions between the azobenzene moieties. However, the [Zn2L(μ-azo-OH)]+ and [Zn2L(μ-azo-O)] complexes are connected by a OH···O hydrogen bond of length 2.46 Å (O3a···O3b, not shown in Figure 4). [Zn2L(μ

• , respectively. These values compare well with those in 3' and other [Zn2L(μ-carboxylato)]+ complexes. The [Zn2L(μ-azo-NMe2)]+ complexes in 5 assemble in pairs (Figure 5) most likely via π···π stacking interactions, as manifested by the distance of 3.34 Å between the planes through the azobenzene moieties. [Cd2L

• radius of Cd2+. The Cd···Cd distance is at 3.399 Å. Virtually the same values are observed in [Cd2L(μ-OAc)]+ [10]. As in 5 π–π stacking of the azo-carboxylato co-ligands occurs (Figure 7). The shortest distance between two carbon atoms of adjacent benzene rings is at 3.41 Å. [Ni2L(μ-Azo-NMe2)]ClO4·xEtOH

Synthesis of functionalized diazocines for application as building blocks in photo- and mechanoresponsive materials

• Widukind Moormann,
• Daniel Langbehn and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 727–732, doi:10.3762/bjoc.15.68

• functionalized compounds are rare [19][20][21][22][23]. In contrary to azobenzenes, diazocines 1 are stable in their cis configuration. The bent cis isomer is less prone to π–π stacking which is known to reduce the switching efficiency (Figure 1a) [19][24]. The reverse stability of the cis and trans isomers in

Targeting the Pseudomonas quinolone signal quorum sensing system for the discovery of novel anti-infective pathoblockers

• Christian Schütz and
• Martin Empting

Beilstein J. Org. Chem. 2018, 14, 2627–2645, doi:10.3762/bjoc.14.241

• (His71) sidechain via π-stacking. For the thiophene-containing fragment 26 a π–π interaction of the sulfur with Phe195 can be observed. In vitro evaluation was performed using a combined PqsDE assay due to the aforementioned instability of 2-ABA-CoA which in this scenario is generated in situ from

• protein [79]. Indicated key interactions are π-stacking of Y258 with the phenoxy moiety in the tail region and a hydrogen bond formed between the Q194 side chain and the carboxamide in the linker area. Furthermore the benzimidazole core shows hydrophobic contacts with isoleucins 149 and 236. More

• Y258M P. aeruginosa mutant strain. The importance of the phenoxy substitutent was further supported by a congener of M64 that lacks this motif and therefore is unable to be involved in π-stacking resulting in a nine-fold increased IC50 value compared to M64. Even though there is no specific interaction

Evaluation of dispersion type metal···π arene interaction in arylbismuth compounds – an experimental and theoretical study

• Ana-Maria Preda,
• Małgorzata Krasowska,
• Lydia Wrobel,
• Philipp Kitschke,
• Phil C. Andrews,
• Jonathan G. MacLellan,
• Lutz Mertens,
• Marcus Korb,
• Tobias Rüffer,
• Heinrich Lang,
• Alexander A. Auer and
• Michael Mehring

Beilstein J. Org. Chem. 2018, 14, 2125–2145, doi:10.3762/bjoc.14.187

• Grimme [54] and Iverson et al. [55] on the unreflected use of terms such as C–H···π, or π···π stacking previously. In most cases, these interactions rely on London dispersion forces rather than special types of bonding due to the π system. Crystal structures In all of the presented compounds, the

• ···π arene type dimers and selected π-stacking dimers were computed at the DLPNO-CCSD(T)/cc-pVQZ (cc-pwCVQZ-PP for Bi) level of theory with TightPNO settings (see Figures 12, 14, and 16). Local energy decomposition analysis was performed in order to obtain the dispersion energy contributions to the

• interaction energies. The dispersion energies of the specific dimers were then visualized as DED plots and are shown in Figures 12, 14, and 16. The structures and interaction energies of all studied π-stacking dimers are given in Supporting Information File 1 (see Figures S12–S14 and Table S4 in Supporting

Functionalization of graphene: does the organic chemistry matter?

• Artur Kasprzak,
• Agnieszka Zuchowska and
• Magdalena Poplawska

Beilstein J. Org. Chem. 2018, 14, 2018–2026, doi:10.3762/bjoc.14.177

• , was assigned to the stretching vibrations of the alkyl chain (commonly observed at up to 2980 cm−1); this absorption band corresponds to the N–H stretching vibrations of NH3+. The further reaction with amphotericin B, which is a compound containing unsaturated bonds, was most plausibly a result of π–π

• stacking. As mentioned above in the discussion of reaction mechanisms, water molecules significantly lower the reaction rates for the desired nucleophiles. Importantly, water molecules also influence the hydrolysis of the activated carboxyl groups (Figure 2, step d and Figure 3, step f). Water should

A self-assembled photoresponsive gel consisting of chiral nanofibers

• Lei Zou,
• Dan Han,
• Zhiyi Yuan,
• Dongdong Chang and
• Xiang Ma

Beilstein J. Org. Chem. 2018, 14, 1994–2001, doi:10.3762/bjoc.14.174

• by three-dimensional networks through self-assembly have drawn significant attention in the past decades. They are normally fabricated by means of noncovalent intermolecular interactions [3], such as π–π stacking, hydrogen bonding, van der Waals forces, hydrophobic, electrostatic, host–guest and

• construct optically controlled systems [17][30][32][33][34][35]. This moiety is also frequently employed as a building block because of its strong π–π stacking in nonpolar solvents. Herein, a novel compound 3 containing both chiral L-glutamic lipid and azobenzene was designed and synthesized (Scheme 1). It

• and π–π stacking in DMSO. However, beautiful acicular fibers could be detected on the surface treated with a chloroform solution, and a dendritic network was observed on the sample made from benzene solution (Figure S9, Supporting Information File 1). The photoresponsiveness of compound 3 was also

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

A pyridinium/anilinium [2]catenane that operates as an acid–base driven optical switch

• Sarah J. Vella and
• Stephen J. Loeb

Beilstein J. Org. Chem. 2018, 14, 1908–1916, doi:10.3762/bjoc.14.165

• the crown ether. In addition, π-stacking interactions induce upfield shifts for protons p, q, v and w from 8.48 ppm in 74+ to 8.24 ppm for [8DB24C8]6+. Protons o, x, n and y do not shift appreciably because the crown ether does not extend far enough to interact with these protons. In contrast, the

Synthesis of 9-arylalkynyl- and 9-aryl-substituted benzo[b]quinolizinium derivatives by Palladium-mediated cross-coupling reactions

• Siva Sankar Murthy Bandaru,
• Darinka Dzubiel,
• Heiko Ihmels,
• Mohebodin Karbasiyoun,
• Mohamed M. A. Mahmoud and
• Carola Schulzke

Beilstein J. Org. Chem. 2018, 14, 1871–1884, doi:10.3762/bjoc.14.161

• quadruplex DNA, the derivatives 2a–d show a typical titration signature for ligands that bind to the quadruplex by terminal π-stacking [14]; however, in analogy to the binding to duplex DNA the derivatives 2b–d form aggregates along the DNA backbone at large ligand–DNA ratio, i.e., at the beginning of the