Binding of tryptophan and tryptophan-containing peptides in water by a glucose naphtho crown ether

• Gianpaolo Gallo and
• Bartosz Lewandowski

Beilstein J. Org. Chem. 2025, 21, 541–546, doi:10.3762/bjoc.21.42

• protons of 1 shifted downfield and a marginal downfield shift of several crown ether protons as well as H-1 and H-3 of the glucopyranose was also observed. These observations suggest that the main interaction between 1 and H-Trp-OH is the π–π stacking between the naphthalene unit of 1 and the indole

Deep-blue emitting 9,10-bis(perfluorobenzyl)anthracene

• Long K. San,
• Sebastian Balser,
• Brian J. Reeves,
• Tyler T. Clikeman,
• Yu-Sheng Chen,
• Steven H. Strauss and
• Olga V. Boltalina

Beilstein J. Org. Chem. 2025, 21, 515–525, doi:10.3762/bjoc.21.39

• ANTH and the –C6F5 group might provide the desired spatial isolation of the ANTH (and other PAH) cores, and result in enhanced photoluminescence by disrupting close π–π stacking in the solid state. In addition, air- and photostability might also be improved due to the steric and electronic properties

Red light excitation: illuminating photocatalysis in a new spectrum

• Lucas Fortier,
• Corentin Lefebvre and
• Norbert Hoffmann

Beilstein J. Org. Chem. 2025, 21, 296–326, doi:10.3762/bjoc.21.22

• involving π–π-stacking [75]. The resulting radical anion releases NO also yielding the anion 63. Electron transfer to the radical cation of the photocatalyst regenerates it. In this step, the neutral radical 64 is also formed. Hydrogen abstraction (hydrogen atom transfer, HAT) yields compound 65. NO and the

Synthesis and characterizations of highly luminescent 5-isopropoxybenzo[rst]pentaphene

• Islam S. Marae,
• Jingyun Tan,
• Rengo Yoshioka,
• Zakaria Ziadi,
• Eugene Khaskin,
• Serhii Vasylevskyi,
• Ryota Kabe,
• Xiushang Xu and
• Akimitsu Narita

Beilstein J. Org. Chem. 2025, 21, 270–276, doi:10.3762/bjoc.21.19

• consisting of four molecules, every two of them are stacked with the plane-to-plane distance of 3.45 Å (Figure 1c), displaying a lamellar π–π stacking motif in the overall packing structure (Figure S1 in Supporting Information File 1) [26][27][28][29]. The X-ray structure is well consistent with a model

Hydrogen-bonded macrocycle-mediated dimerization for orthogonal supramolecular polymerization

• Wentao Yu,
• Zhiyao Yang,
• Chengkan Yu,
• Xiaowei Li and
• Lihua Yuan

Beilstein J. Org. Chem. 2025, 21, 179–188, doi:10.3762/bjoc.21.10

• noncovalent interactions, particularly intermolecular π–π-stacking and C–H···O interactions. Specifically, π–π-stacking interactions were found between two guest molecules with aromatic rings arrayed in an offset fashion with a distance of 3.3 Å (Figure 3a). Interestingly, these interactions also existed

• the π–π-stacking distances (d[π···π] = 3.3–3.4 Å) between H2 and G1. The side chains of H2 were replaced by a methyl group, all hydrogen atoms except amide groups, solvent molecules, and counterions were omitted for clarity. Stacked 1H NMR spectra (CDCl3/CD3CN 1:1, v/v, 400 MHz, 298 K) of G2 upon

Non-covalent organocatalyzed enantioselective cyclization reactions of α,β-unsaturated imines

• Sergio Torres-Oya and
• Mercedes Zurro

Beilstein J. Org. Chem. 2024, 20, 3221–3255, doi:10.3762/bjoc.20.268

• quinuclidine moiety can act as a base activating a nucleophile, secondly the secondary hydroxy group can participate in hydrogen bonding or can behave as a Brønsted acid (Figure 5). Additionally, the quinoline moiety can interact through π–π stacking with the reactants. On the other hand, the (DHQD)2-based

• to the nitro group, resulting in the formation of an anionic nucleophilic specie A. The latter reacts with the cyclic 1-azadiene via stereoselective Michael addition, forming intermediate B, stabilized by π–π stacking interactions between the Ar group and the aromatic cyclic moiety of the 1-azadiene

Synthesis of the 1,5-disubstituted tetrazole-methanesulfonylindole hybrid system via high-order multicomponent reaction

• Cesia M. Aguilar-Morales,
• América A. Frías-López,
• Nadia V. Emilio-Velázquez,
• Alejandro Islas-Jácome,
• Angelica Judith Granados-López,
• Jorge Gustavo Araujo-Huitrado,
• Yamilé López-Hernández,
• Hiram Hernández-López,
• Luis Chacón-García,
• Jesús Adrián López and
• Carlos J. Cortés-García

Beilstein J. Org. Chem. 2024, 20, 3077–3084, doi:10.3762/bjoc.20.256

• combining the indole moiety with the 1,5-disusbtituted tetrazole pharmacophore could increase the non-covalent interactions, including π–π stacking, hydrogen bonding, and hydrophobic interactions. This combination may improve the pharmacodynamic profile, providing a solid foundation for developing compounds

The charge transport properties of dicyanomethylene-functionalised violanthrone derivatives

• Sondos A. J. Almahmoud,
• Joseph Cameron,
• Dylan Wilkinson,
• Michele Cariello,
• Claire Wilson,
• Alan A. Wiles,
• Peter J. Skabara and
• Graeme Cooke

Beilstein J. Org. Chem. 2024, 20, 2921–2930, doi:10.3762/bjoc.20.244

• one with branched alkyl chains, 3a. This could be the result of the more highly disordered packing arrangement of this molecule in the solid state, induced by the branched side chains that hinder the formation of π–π stacking interactions. The influence of dicyanomethylene groups on the charge

• , organic semiconductor molecules with large fused conjugated systems have achieved high charge carrier mobility. Such molecular structures improve the intermolecular interactions (such as π–π stacking) that are required to facilitate the hopping of charge carriers between adjacent molecules [7][8][9

• pass through the device [30]. The π–π intermolecular interactions, the molecular stacking and mobility of a solution-processable violanthrone derivative has been studied. It was shown that π–π stacking can be enhanced in solution and in the solid state by adding a non-solvent (n-hexane) to chloroform

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

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

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

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

• 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

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 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

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

Active-metal template clipping synthesis of novel [2]rotaxanes

• Cătălin C. Anghel,
• Teodor A. Cucuiet,
• Niculina D. Hădade and
• Ion Grosu

Beilstein J. Org. Chem. 2023, 19, 1776–1784, doi:10.3762/bjoc.19.130

• ) [30][31], metal-ion template (coordination bonds [22][32], ion-dipol [16], donor–acceptor (charge transfer, π–π stacking) [30][33], and oligoamide macrocycle-hydrogen acceptors (hydrogen bonding) [20][34]. In active-metal template methods (Figure 1) the metal ion acts both as template and catalyst for

Quinoxaline derivatives as attractive electron-transporting materials

• Zeeshan Abid,
• Liaqat Ali,
• Sughra Gulzar,
• Faiza Wahad,
• Raja Shahid Ashraf and
• Christian B. Nielsen

Beilstein J. Org. Chem. 2023, 19, 1694–1712, doi:10.3762/bjoc.19.124

• crystallinity and optical absorption but a shorter π–π stacking distance. OSC devices based on Qx23 and Qx25 achieved the highest PCE (10.67 and 12.19%, respectively) compared to Qx22 and Qx24 (6.94 and 8.01%, respectively) [35]. Xiao and fellows studied the impact of side chains on molecular packing and

• section "Quinoxalines as polymer acceptors" also fabricated OFETs using QxCN-based polymer acceptors and demonstrated unipolar n-type characteristics with moderate OFET mobilities. The well-ordered structures with tight π–π stacking in Qx2 and Qx3 contributed to electron mobilities greater than 1.0 × 10−4