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

• the tweezers to selectively bind aromatic guests within a cavity, utilizing an induced fit mechanism. Subsequently, with the emergence and advancement of supramolecular chemistry, the field of molecular tweezers experienced rapid expansion, witnessing the development of rigid clips by Klärner [2] and

• tweezers with tert-butyl groups positioned farther from the salphen via alkyne spacers were synthesized [42]. While, like in the parent tweezers 12, no intercalation of aromatic guests was observed in the closed form, strong intramolecular and intermolecular Pt–Pt bonds were achieved in the solid state

• . Vives and co-workers reported bis(platinum–salphen)terpyridine tweezers 20 that can intercalate in the U form extended aromatic guests such as coronene and perylene [52]. The opening of the tweezers with the addition of Zn2+ released the guest demonstrating an example of negative allosteric regulation

Synthesis of a [6]rotaxane with singly threaded γ-cyclodextrins as a single stereoisomer

• Jason Yin Hei Man and
• Ho Yu Au-Yeung

Beilstein J. Org. Chem. 2019, 15, 1829–1837, doi:10.3762/bjoc.15.177

• relatively large cavity size that could accommodate up to two aromatic guests to form 1:2 host–guest complexes, in contrast to the usual formation of 1:1 complex by α-CD and β-CD [10][11]. In addition to host–guest chemistry, the favourable binding of CDs to common organic scaffolds has also made CDs popular

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

• because of their varying cavity rigidity and larger portal sizes as compared with those of other macrocyclic hosts [4][5][6][7][8][9][10][11][12][13]. For example, cucurbit[8]uril (Q[8] or CB[8]), a large homologue of the Q[n] family, is unique because of its ability to bind two hetero- and homo-aromatic

• guests in its cavity through host-stabilized charge-transfer or π–π interactions [14][15]. This novel property of Q[8] has been utilized as molecular container for biological substrates [16][17], as well as in the construction of various supramolecular assemblies with specific structures and properties

A three-armed cryptand with triazine and pyridine units: synthesis, structure and complexation with polycyclic aromatic compounds

• Claudia Lar,
• Adrian Woiczechowski-Pop,
• Attila Bende,
• Ioana Georgeta Grosu,
• Natalia Miklášová,
• Elena Bogdan,
• Niculina Daniela Hădade,
• Anamaria Terec and
• Ion Grosu

Beilstein J. Org. Chem. 2018, 14, 1370–1377, doi:10.3762/bjoc.14.115

• are reported. Appropriate NMR and molecular modelling investigations proved the formation of 1:1 host–guest assemblies between the investigated cryptand and some polynuclear aromatic hydrocarbons or their derivatives. Keywords: aromatic guests; aromatic nucleophilic substitution; cryptand; NMR

• neutral guests, e.g., aromatic molecules [2][3][4][5][6]. The supramolecular architectures involving cryptands (including metallomacrocycles) and aromatic guests are targeted for investigations of aromatic–aromatic contacts [7][8] and for various applications in molecular electronics [9][10]. The recently

• 1 towards aromatic guests (anthracene, pyrene) in solution was observed and the formation of a cryptand–pyrene complex was revealed by cyclic voltammetry only after the adsorption of the cryptand on a graphite surface (electrode). In a more recent paper [33], authors who reobtained our cryptand 1

Nanoreactors for green catalysis

• M. Teresa De Martino,
• Loai K. E. A. Abdelmohsen,
• Floris P. J. T. Rutjes and
• Jan C. M. van Hest

Beilstein J. Org. Chem. 2018, 14, 716–733, doi:10.3762/bjoc.14.61

• were assembled from hydrophilic poly(ethylene oxide) (PEO) and hexa-p-phenylene, providing a platform for Suzuki reactions with the hydrophobic core acting as a suitable pocket for apolar aromatic guests [71][72]. With such a platform, full conversion was achieved at room temperature in water. Almost

Synthesis and photophysical characteristics of polyfluorene polyrotaxanes

• Aurica Farcas,
• Giulia Tregnago,
• Ana-Maria Resmerita,
• Pierre-Henri Aubert and
• Franco Cacialli

Beilstein J. Org. Chem. 2015, 11, 2677–2688, doi:10.3762/bjoc.11.288

• architectures [39]. The second most investigated group of host molecules in the synthesis of conjugated polyrotaxanes is comprised of chemically-modified CDs. They are less hydrophilic than native CDs, and should exhibit a significantly increased ability to bind aromatic guests through ionic, ion-dipole, as

Properties of cationic monosubstituted tetraalkylammonium cyclodextrin derivatives – their stability, complexation ability in solution or when deposited on solid anionic surface

• Martin Popr,
• Sergey K. Filippov,
• Nikolai Matushkin,
• Juraj Dian and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2015, 11, 192–199, doi:10.3762/bjoc.11.20

• PEMPDA-β-CD in solution with a series of simple aromatic guests (salicylic acid, p-methoxyphenol and p-nitroaniline) were determined by isothermal titration calorimetry (ITC) and compared to the native β-CD. Permanently charged cationic CD derivatives were successfully deposited on the anionic solid

• (PErMethylated EthyleneDiAmine substituted). Its binding ability toward selected aromatic guests is compared to the native β-CD at different pH. Deposition of PEMPDA-β-CD on the surface of an anionic Nafion® 117 membrane via ionic self-assembly was also studied along with the determination of sorption kinetics

• and surface coverage. Finally, the ability of the PEMPDA-β-CD bound to the solid surface to accommodate aromatic guests from aqueous solution into the cavities was explored. Results and Discussion Thermal stability of PEMEDA- and PEMPDA-β-CD It is generally known, that quaternary ammonium salts

Effect of cyclodextrin complexation on phenylpropanoids’ solubility and antioxidant activity

• Miriana Kfoury,
• David Landy,
• Lizette Auezova,
• Hélène Greige-Gerges and
• Sophie Fourmentin

Beilstein J. Org. Chem. 2014, 10, 2322–2331, doi:10.3762/bjoc.10.241

• ]. Molecular modeling demonstrated that the aromatic ring and the side chain of PPs were embedded inside the cavity of β-CD, leaving the more polar groups exposed at the periphery of the cavity. These results confirm that formation of inclusion complexes between CD and aromatic guests occurs by the prevalence

Topochemical control of the photodimerization of aromatic compounds by γ-cyclodextrin thioethers in aqueous solution

• Hai Ming Wang and
• Gerhard Wenz

Beilstein J. Org. Chem. 2013, 9, 1858–1866, doi:10.3762/bjoc.9.217

• aromatic guests under controlled, homogenous reaction conditions. The quantum yields for unsubstituted anthracene, acenaphthylene, and coumarin complexed in these γ-CD thioethers were found to be up to 10 times higher than in the non-complexed state. The configuration of the photoproduct reflected the

• topochemical reaction. This type of topochemical control happening in solution is much more applicable than the classical topochemical control occurring in the crystalline state [3][43][49]. Conclusion Aromatic guests ANT, ACE, and COU form 1:2 (host/guest) complexes within γ-CD thioethers 1–7, which

• , respectively [50]. Chemical structures of selected aromatic guests: anthracene, ANT; acenaphthylene, ACE; and coumarin, COU. Structures of γ-CD and γ-CD thioethers 1–7. 1H NMR spectrum of the photo product of ACE in the presence of γ-CD thioether 3 in CDCl3. Schematic drawing of the ACE photodimers in γ-CD: a

Space filling of β-cyclodextrin and β-cyclodextrin derivatives by volatile hydrophobic guests

• Sophie Fourmentin,
• Anca Ciobanu,
• David Landy and
• Gerhard Wenz

Beilstein J. Org. Chem. 2013, 9, 1185–1191, doi:10.3762/bjoc.9.133

• -CD 2, and β-CD-thioethers 3 and 4. Chemical structures of the benzene and cyclohexane derivatives, with their calculated molecular volumes, VG = M/dNA in Å3, with M molecular weight, d density, NA Avogadro’s number. Chromatogram obtained by HS-GC for a mixture of aromatic guests (1 ppm) in water

Molecular recognition of organic ammonium ions in solution using synthetic receptors

• Andreas Späth and
• Burkhard König

Beilstein J. Org. Chem. 2010, 6, No. 32, doi:10.3762/bjoc.6.32

• separation problems several approaches are available. A general trend is observable: 18-crown-6-systems reveal higher binding constants then 15-crown-5-systems, due to the better size fit of the guest ion. Aromatic substituents lead to better recognition and enantiomeric excess (up to 70%) with aromatic

• guests such as NEA (20a) or phenylglycinol (20c). For tryptophan (81b) the best results were achieved with selection factors of one enantiomer over the other up to 13 fold, corresponding to over 90% ee. This is explained by π–π-interactions. Besides chiral substituents on the crown ether ring, chiral

Control of stilbene conformation and fluorescence in self-assembled capsules

• Mark R. Ams,
• Dariush Ajami,
• Stephen L. Craig,
• Jye-Shane Yang and
• Julius Rebek Jr

Beilstein J. Org. Chem. 2009, 5, No. 79, doi:10.3762/bjoc.5.79

• ) The shape of the space inside (A), a schematic view along the central axis with two aromatic guests (B) and an energy-minimized (AM1) complex of stilbene in 1.1 (C). Room temperature fluorescence spectra at λexc = 318 nm for 10 µM mesitylene solutions of 4,4′-dimethylstilbene (2); 4-ethyl-4

• with two aromatic guests (B) and an end-on view of an energy-minimized complex of stilbene inside (C). Room temperature emission spectra for 10 µM solutions of 4-ethyl-4′-ethylstilbene (3) in the capsule 1.1 (6) and 1.74.1 (8). λexc = 318 nm. Supporting Information Supporting Information File 112