Anion-dependent ion-pairing assemblies of triazatriangulenium cation that interferes with stacking structures

• Yohei Haketa,
• Takuma Matsuda and
• Hiromitsu Maeda

Beilstein J. Org. Chem. 2024, 20, 2567–2576, doi:10.3762/bjoc.20.215

• +) cations, used as visible light fluorescent dyes, have been synthesized via a nucleophilic aromatic substitution (SNAr) reaction with primary alkylamines (e.g., 1a+; Figure 1) [15][16]. The highly planar geometry of the TATA+ core unit induces π–π stacking structures in single-crystal and film states, as

• in the other TATA+ cations that form π–π stacking structures [11][12][15][16][22]. The angles between the two staggered TATA+ planes were 53.7° and 51.4° for 2+-BF4− and 2+-PF6−, respectively. The orthogonal arrangement of TATA+ and the o-CH3-substituted aryl units was suitable for forming

Asymmetric organocatalytic synthesis of chiral homoallylic amines

• Nikolay S. Kondratyev and
• Andrei V. Malkov

Beilstein J. Org. Chem. 2024, 20, 2349–2377, doi:10.3762/bjoc.20.201

• 78 with a pending 4-pyrenyl group. The catalyst acts as H-bond donor but additionally it controls the chiral environment through π-stacking interaction with the aryl group of the substrate, blocking one of the enantiofaces of the iminium intermediate 79. The reaction proceeds in Et2O at −50 °C and

• (trifluoromethylphenyl) group with other fluorinated aromatics (86–90) showed a gradual decrease in ee (92% ee in 90 to 68% ee in 86 and 88) depending on the degree of fluorination. Computational modelling for the 3,5-bis(trifluoromethylphenyl) catalyst 78 revealed that π-stacking interactions of the 4-pyrene group with

• give the desired product 99 after 72 h returning hemiaminal (Scheme 21). Alkyl acetals, such as cyclohexyl carboxaldehyde acetal reacted sluggishly with low yield and selectivity (<10% yield, 43–50% ee), possibly due to their inability to participate in π–π interactions. In general, the π-stacking

Novel truxene-based dipyrromethanes (DPMs): synthesis, spectroscopic characterization and photophysical properties

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2024, 20, 2163–2170, doi:10.3762/bjoc.20.186

• -planar having π‐conjugation [2][3][4]. Remarkably, these unique characteristics of the truxene scaffold, results in strong π–π stacking ability in addition to the strong electron‐donating capability – hinting for the truxene’s capability as a worthy building block in the advancement of cutting-edge

Understanding X-ray-induced isomerisation in photoswitchable surfactant assemblies

• Beatrice E. Jones,
• Camille Blayo,
• Jake L. Greenfield,
• Matthew J. Fuchter,
• Nathan Cowieson and
• Rachel C. Evans

Beilstein J. Org. Chem. 2024, 20, 2005–2015, doi:10.3762/bjoc.20.176

• , Supporting Information File 1). This morphology change can be attributed to two changes in the AAPTAB on E–Z isomerisation [19]. Firstly, the shape change of the AAPTAB to the bent, “T-shape” conformation prevents the π–π stacking which was previously possible in the more planar, E isomers that were arranged

Synthesis and characterization of 1,2,3,4-naphthalene and anthracene diimides

• Adam D. Bass,
• Daniela Castellanos,
• Xavier A. Calicdan and
• Dennis D. Cao

Beilstein J. Org. Chem. 2024, 20, 1767–1772, doi:10.3762/bjoc.20.155

• -Ph as determined by X-ray crystallography. Representative C=O···H–C and C–H···π interactions are indicated in teal and magenta, respectively. Top-down views of π-stacking modes in c) 7-Ph and d, e) 8-Ph. Hydrogen atoms have been removed for clarity in c–e. Atom color code: C = tan, H = white, Cl

Supramolecular assemblies of amphiphilic donor–acceptor Stenhouse adducts as macroscopic soft scaffolds

• Ka-Lung Hung,
• Leong-Hung Cheung,
• Yikun Ren,
• Ming-Hin Chau,
• Yan-Yi Lam,
• Takashi Kajitani and
• Franco King-Chi Leung

Beilstein J. Org. Chem. 2024, 20, 1590–1603, doi:10.3762/bjoc.20.142

• = 2.24 nm could be attributed to the longer molecular axis of DA11 in dimer form, while that at d = 0.36 nm originated from π–π stacking of the DASA motif. Consistently, diffraction from the longer molecular axis of DA10 in dimer form was shorter (d = 2.19 nm) than that of DA11, revealing the subtle

• π–π stacking of the DASA motifs. However, no significant unidirectional alignment was observed in WAXD and SEM images of DA7 and DA6 macroscopic soft scaffolds (Figure S11a and S11c as well as S12a and S12c, Supporting Information File 1, respectively). Electron microscopy and WAXD revealed that a

Generation of alkyl and acyl radicals by visible-light photoredox catalysis: direct activation of C–O bonds in organic transformations

• Mithu Roy,
• Bitan Sardar,
• Itu Mallick and
• Dipankar Srimani

Beilstein J. Org. Chem. 2024, 20, 1348–1375, doi:10.3762/bjoc.20.119

• radical cation 81 and Mes–Acr because of the favorable π–π stacking. Ethyl vinyl ether, which is the most nucleophilic molecule in the reaction, combined with radical cation 81 to form the oxonium radical 82, which could proceed in two directions: 1) β-elimination, yielding radical 83 and 2) photoinduced

Synthesis of indano[60]fullerene thioketone and its application in organic solar cells

• Yong-Chang Zhai,
• Shimon Oiwa,
• Shinobu Aoyagi,
• Shohei Ohno,
• Tsubasa Mikie,
• Jun-Zhuo Wang,
• Hirofumi Amada,
• Koki Yamanaka,
• Kazuhira Miwa,
• Naoyuki Imai,
• Takeshi Igarashi,
• Itaru Osaka and
• Yutaka Matsuo

Beilstein J. Org. Chem. 2024, 20, 1270–1277, doi:10.3762/bjoc.20.109

• -butyl groups, which disrupted the π–π stacking between the fullerene cages. The slight difference in sublimation temperature between t-Bu-FIDO and t-Bu-FIDS might be due to the slightly higher electron density of the sulfur atom compared with the oxygen atom. Additionally, data on the degradation

Introduction of peripheral nitrogen atoms to cyclo-meta-phenylenes

• Koki Ikemoto and
• Hiroyuki Isobe

Beilstein J. Org. Chem. 2024, 20, 1207–1212, doi:10.3762/bjoc.20.103

• π-stacking may also enable exploration of molecular assemblies. The experimental lone-pair electron densities were directed outward in 3a and could be used as linkers for metal atoms to assemble trigonal pyramidal macrocycles, for instance, in networks of metal organic frameworks [23][24

Light on the sustainable preparation of aryl-cored dibromides

• Fabrizio Roncaglia,
• Alberto Ughetti,
• Nicola Porcelli,
• Biagio Anderlini,
• Andrea Severini and
• Luca Rigamonti

Beilstein J. Org. Chem. 2024, 20, 1076–1087, doi:10.3762/bjoc.20.95

• ], photonics [2], and diagnostics [3]. Their popularity stems from their structural rigidity, potential conjugation with the remaining structure, and the capability to form additional π–π-stacking interactions. Dihalides, in particular, are highly preferred in such applications, enabling the formation of

Structure–property relationships in dicyanopyrazinoquinoxalines and their hydrogen-bonding-capable dihydropyrazinoquinoxalinedione derivatives

• Tural N. Akhmedov,
• Ajeet Kumar,
• Daken J. Starkenburg,
• Kyle J. Chesney,
• Khalil A. Abboud,
• Novruz G. Akhmedov,
• Jiangeng Xue and
• Ronald K. Castellano

Beilstein J. Org. Chem. 2024, 20, 1037–1052, doi:10.3762/bjoc.20.92

• and charge injection/extraction processes [7]. The additional merits of H-bonding designs in organic optoelectronic materials include higher thermal stability, synergistic stabilizing effects with π-stacking interactions, etc. [8]. Acenes and N-heteroacenes are two prominent π-conjugated scaffolds for

• favorable π–π stacking in the solid state. The 5% weight loss values range from 232 °C to 353 °C. Compounds with larger π-surfaces exhibited greater thermal stability (353 °C for 3a, 304 °C for 4a, 312 °C for 6a) while others displayed 5% weight loss values under 250 °C (232 °C for 1a, 244 °C for 2a and 238

• packing of 2b is expected to be favorable for charge mobility within stacked arrangements [36][37]. Additionally, the intermolecular π–π stacking distance is reduced to 3.285 Å in the staggered form (Figure 6f and 6g), 0.27 Å shorter than its non-hydrogen bonding dicyano comparator 2a. The single-crystal

Spin and charge interactions between nanographene host and ferrocene

• Akira Suzuki,
• Yuya Miyake,
• Ryoga Shibata and
• Kazuyuki Takai

Beilstein J. Org. Chem. 2024, 20, 1011–1019, doi:10.3762/bjoc.20.89

• material design should be important in this viewpoint, especially in choosing appropriate guest molecules. Since π electrons extend to in-plane directions in nanographene, a guest molecule with an aromatic ring is promising for significant interaction with the nanographene host through π–π stacking

• mesoporous silica (MCM-41) [18]. So, ferrocene is expected to exhibit strong host–guest interactions with a nanographene host through π–π stacking. Regarding ferrocene as a guest molecule for nanocarbon hosts, carbon nanotubes (CNTs) have been used to accommodate guest ferrocene molecules, where the amount

Skeletal rearrangement of 6,8-dioxabicyclo[3.2.1]octan-4-ols promoted by thionyl chloride or Appel conditions

• Martyn Jevric,
• Julian Klepp,
• Johannes Puschnig,
• Oscar Lamb,
• Christopher J. Sumby and
• Ben W. Greatrex

Beilstein J. Org. Chem. 2024, 20, 823–829, doi:10.3762/bjoc.20.74

• Diels–Alder adducts of 1, and similar results on the effect of configuration were observed [21]. During some recent attempts at the chlorination of the π-stacking chiral auxiliary 10a using SOCl2 [9], we observed the migration of O8 resulting in the formation of anomeric chlorides analogous to the

Possible bi-stable structures of pyrenebutanoic acid-linked protein molecules adsorbed on graphene: theoretical study

• Yasuhiro Oishi,
• Motoharu Kitatani and
• Koichi Kusakabe

Beilstein J. Org. Chem. 2024, 20, 570–577, doi:10.3762/bjoc.20.49

• reported. The adsorption of PASE has been considered to mainly come from the pyrene fragment, which forms π–π stacking on these graphitic carbon materials [6][7][8]. The sensitivity of the oscillator-based sensor depends on the structure of the linker molecule. Therefore, understanding the adsorption

Synthesis of photo- and ionochromic N-acylated 2-(aminomethylene)benzo[b]thiophene-3(2Н)-ones with a terminal phenanthroline group

• Vladimir P. Rybalkin,
• Sofiya Yu. Zmeeva,
• Lidiya L. Popova,
• Irina V. Dubonosova,
• Olga Yu. Karlutova,
• Oleg P. Demidov,
• Alexander D. Dubonosov and
• Vladimir A. Bren

Beilstein J. Org. Chem. 2024, 20, 552–560, doi:10.3762/bjoc.20.47

• the phenanthroline unit was also involved in a π–π-stacking interaction (blue plane–green plane in Figure 4), with the plane centroid–plane centroid distance being 3.6998(8) Å (plane shift 1.4919(17) Å, twist and fold angles 1.54° and 1.92°, respectively). Cation-induced transformations of the

Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

• quenched when the tweezers are closed by the addition of a Zn2+ cation because of intramolecular π–π stacking interactions between the chromophores. The system can be reopened and its luminescence properties restored by introducing tris(2-aminoethyl)amine (TREN), which has a better affinity for Zn2+ and

• square planar conformation giving an almost parallel arrangement of the aryl arms. This creates a cavity able to complex small coordinating guests that interact with the copper as ligands and also with the arms through π–π stacking. This system is selective towards flat aromatic guests and towards

Synthesis of 2,2-difluoro-1,3-diketone and 2,2-difluoro-1,3-ketoester derivatives using fluorine gas

• Alexander S. Hampton,
• David R. W. Hodgson,
• Graham McDougald,
• Linhua Wang and
• Graham Sandford

Beilstein J. Org. Chem. 2024, 20, 460–469, doi:10.3762/bjoc.20.41

• intermolecular interactions with an aryl ring in an adjacent molecule. The two aryl rings within the molecule are near-perpendicular to each other and this conformation leads to enhanced, orthogonal π-stacking interactions. We next turned our attention to difluorination of related 2-ketoester substrates

Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters

• Carlos R. Azpilcueta-Nicolas and
• Jean-Philip Lumb

Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35

• ) for π-stacking between the furan and phthalimide rings, before EnT from *IrIII leads to the formation of an excited charge-transfer complex 47. This species would undergo intramolecular electron transfer (IET) giving rise to intermediate 48, which upon fragmentation would form radical 49

Elucidating the glycan-binding specificity and structure of Cucumis melo agglutinin, a new R-type lectin

• Jon Lundstrøm,
• Emilie Gillon,
• Valérie Chazalet,
• Nicole Kerekes,
• Antonio Di Maio,
• Ten Feizi,
• Yan Liu,
• Annabelle Varrot and
• Daniel Bojar

Beilstein J. Org. Chem. 2024, 20, 306–320, doi:10.3762/bjoc.20.31

• nitrogen. CH−π stacking and hydrophobic interactions occur between the aromatic ring of Trp36 and the alpha face of the ring as well as the hydroxymethyl moiety of the galactose residue, additionally ensuring specificity for galactoside over glucoside as an equatorial conformation of the O4 hydroxy group

Synthesis of π-conjugated polycyclic compounds by late-stage extrusion of chalcogen fragments

• Aissam Okba,
• Pablo Simón Marqués,
• Kyohei Matsuo,
• Naoki Aratani,
• Hiroko Yamada,
• Gwénaël Rapenne and
• Claire Kammerer

Beilstein J. Org. Chem. 2024, 20, 287–305, doi:10.3762/bjoc.20.30

• devices [1][2][3][4][5][6][7][8]. In this regard, the planar character of most (non-substituted) π-CPCs represents a challenge, as it results in very low solubility in common organic solvents due to favorable intermolecular π–π stacking interactions. This inherently hampers the purification of the target

• conformation of the thiepine ring, thus weakening the π–π stacking intermolecular interactions. Finally, solid-state S-extrusion could be triggered in a controlled way upon thermal activation of 21, as observed in thermogravimetric analysis, with the loss of sulfur detected at 223 °C to yield the planar S

Substitution reactions in the acenaphthene analog of quino[7,8-h]quinoline and an unusual synthesis of the corresponding acenaphthylenes by tele-elimination

• Ekaterina V. Kolupaeva,
• Narek A. Dzhangiryan,
• Alexander F. Pozharskii,
• Oleg P. Demidov and
• Valery A. Ozeryanskii

Beilstein J. Org. Chem. 2024, 20, 243–253, doi:10.3762/bjoc.20.24

• reaction with neutral or anionic bases. Keywords: dipyrido[3,2-e:2′,3′-h]acenaphthene (acenaphthylene); hydrogen bonding; π-stacking; substitution reactions; tele-elimination; Introduction Quinoline derivatives, classical nitrogen-containing heterocycles, are widely distributed in nature in various forms

• ), and on the other hand, by π-stacking of the antiparallel protonated dipyridoacenaphthene fragments (two-dimensional dense stacks with an interplanar distance of 3.377 Å). Their combination is the main driving force behind the formation of the final supramolecular zipper structure. Interestingly, the

• value lies in the range of 2.51–2.61 Å, strongly resemble the bifurcated hydrogen bonds so characteristic of base 5, additionally reinforced by π-stacking between the terminal components in each H-associated triad (the shortest distance between the antiparallel π-systems of two molecular planes here is

Photochromic derivatives of indigo: historical overview of development, challenges and applications

• Gökhan Kaplan,
• Zeynel Seferoğlu and
• Daria V. Berdnikova

Beilstein J. Org. Chem. 2024, 20, 228–242, doi:10.3762/bjoc.20.23

• melting point of indigo is bifurcated intra- and intermolecular hydrogen bonding [11], and face-to-face π–π stacking of parallel aromatic rings (Figure 2) [12]. Single crystal X-ray diffraction analysis showed that the indigo molecule is almost planar and exists in the E-conformation. The central C=C bond

Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

• Michio Yamada

Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13

• arising from hydrogen bonding and π–π stacking interactions. In contrast, when 75 is incorporated into a nanocomposite with polystyrene serving as the matrix, luminescent properties are observed [141]. Photoinduced intramolecular energy and electron transfer Exploiting the electron-accepting property of

Facile access to pyridinium-based bent aromatic amphiphiles: nonionic surface modification of nanocarbons in water

• Lorenzo Catti,
• Shinji Aoyama and
• Michito Yoshizawa

Beilstein J. Org. Chem. 2024, 20, 32–40, doi:10.3762/bjoc.20.5

• similar to AA [12][13], indicating self-assembly via the hydrophobic effect and π-stacking interactions (Figure 3a,b). The self-assembly in water was further supported by UV–visible analysis, displaying slight red-shifts of the anthracene absorption bands relative to the spectrum in methanol (Δλmax = +3

• below 0.1 mM (Figures S28 and S32, Supporting Information File 1), which is around 10 times lower than that of AA [12][13]. The increased stability against dilution likely arises from reduced electrostatic repulsion and increased anthracene-based π-stacking interactions due to the absence of o-alkoxy

• materials. Conclusion We have developed new pyridinium-based bent amphiphiles PA-R that can be facilely accessed from simple yet novel building block 3,5-dianthrylpyridine in 1–3 steps. The amphiphiles quantitatively self-assembled into ≈2 nm-sized aromatic micelles (PA-R)n via the hydrophobic effect and π

Anion–π catalysis on carbon allotropes

• M. Ángeles Gutiérrez López,
• Mei-Ling Tan,
• Giacomo Renno,
• Augustina Jozeliūnaitė,
• J. Jonathan Nué-Martinez,
• Javier Lopez-Andarias,
• Naomi Sakai and
• Stefan Matile

Beilstein J. Org. Chem. 2023, 19, 1881–1894, doi:10.3762/bjoc.19.140

• -to-face π stacking because the delocalized π electrons move within the stack away from the charge, which induces a macrodipole along the stack that supports the binding of the anion (Figure 1B) [61]. What works for anion–(π)n–π catalysis on π-stacked foldamers [61] and micelles [8] should apply to