Photomechanochemistry: harnessing mechanical forces to enhance photochemical reactions

• Francesco Mele,
• Ana M. Constantin,
• Andrea Porcheddu,
• Raimondo Maggi,
• Giovanni Maestri,
• Nicola Della Ca’ and
• Luca Capaldo

Beilstein J. Org. Chem. 2025, 21, 458–472, doi:10.3762/bjoc.21.33

• optimal temperature regulation using a fan. To overcome the challenge posed by the non-transparency of milling jars, a glass capsule was utilized. Teflon balls were employed to grind the reagents, thereby minimizing wear on the milling vessel. As a benchmark reaction, they selected the photochemical

Beyond symmetric self-assembly and effective molarity: unlocking functional enzyme mimics with robust organic cages

• Keith G. Andrews

Beilstein J. Org. Chem. 2025, 21, 421–443, doi:10.3762/bjoc.21.30

• to create an internal cavity (Figure 4A). Since the parts of the capsule are dynamically assembled, substrates and products are able to enter and exit via partial disassembly of the capsule [118], with the only requirement being that they must fit inside [119]. Many of these capsules perform simple

• a size-selective space [105][126][129][130][132][134]. A key advantage is that these capsules have been made on multi-hundred-gram scales and can be recycled [132]. Additionally, control of structural or bound water by the capsule [105] and properties such as a lowered pKa inside [125] demonstrate a

• rare example of a cavity-promoting catalysis via both “organization and polarization” (Figure 4C), including dual activation [105], albeit with vague directionality (the substrate can be productively oriented in many conformations). This directionality might be advanced by new capsule types. For

Advances in the use of metal-free tetrapyrrolic macrocycles as catalysts

• Mandeep K. Chahal

Beilstein J. Org. Chem. 2024, 20, 3085–3112, doi:10.3762/bjoc.20.257

• , Ballester and co-workers reported on the preparation of an octapyridinium-based water-soluble superaryl-extended calix[4]pyrrole molecular container and used it as a capsule for desymmetrization reactions [41], where the reported compound acts both as sequestering and supramolecular protecting group. All of

Spatial arrangements of cyclodextrin host–guest complexes in solution studied by ¹³C NMR and molecular modelling

• Konstantin Lebedinskiy,
• Ivan Barvík,
• Zdeněk Tošner,
• Ivana Císařová,
• Jindřich Jindřich and
• Radim Hrdina

Beilstein J. Org. Chem. 2024, 20, 331–335, doi:10.3762/bjoc.20.33

• -cyclodextrins. Compounds 1, 6 and 8 are commercial, compounds 2–5 [21] and 7 [22] were prepared according to published procedures. Compound 2 (as a free amine) crystallized in the supramolecular capsule of two α-cyclodextrins, and the mono-crystal was subjected to X-ray analysis. This experiment was performed

• supramolecular capsule with noradamantane-3-methyleneamine (2) as guest molecule (side and top view). Supporting Information Supporting Information File 38: General information, NMR spectra, NMR study, computational study, crystallographic data collection and refinement details. Funding This work has been

Preparation of β-cyclodextrin-based dimers with selectively methylated rims and their use for solubilization of tetracene

• Konstantin Lebedinskiy,
• Volodymyr Lobaz and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2022, 18, 1596–1606, doi:10.3762/bjoc.18.170

• 13 (β-CD) has also shown poor solubilizing activity. We suggest that the presence of hydroxy groups on the secondary rim of CD allows the hydrogen bond formation between two molecules, creating a capsule (tail-to-tail interaction, Figure 6a). It seems the generation of such capsules in solution

• disfavors the complexation with tetracene. The compounds with occupied secondary rims, such as 16 and 17, have shown better effectiveness, losing only to the dimers. A spacer connecting two primary rims in a dimer promotes the interaction between them, forming a capsule with the inverted orientation of CD

Supramolecular approaches to mediate chemical reactivity

• Pablo Ballester,
• Qi-Qiang Wang and
• Carmine Gaeta

Beilstein J. Org. Chem. 2022, 18, 1463–1465, doi:10.3762/bjoc.18.152

• capsule can catalyze the cyclization of (S)-citronellal forming isopulegol. In this study it was exploited the ability of the resorcinarene capsule to work as a Brønsted acid catalyst, and its aptitude to stabilize cationic intermediates and transition states inside the cavity. Velmurugan, Hu and co

Polymer and small molecule mechanochemistry: closer than ever

• José G. Hernández

Beilstein J. Org. Chem. 2022, 18, 1225–1235, doi:10.3762/bjoc.18.128

• the covalent capsule 5 (made from resorcinarene caps connected by four dihydrazone units of ʟ-cysteine) with C60 and C70 fullerenes upon neat ball milling in a planetary ball mill (Figure 6). The mechanochemical complexation is remarkable since the porous capsule does not possess large enough openings

• for the fullerenes to pass through. However, the capsule 5 is sensitive to mechanochemical stress due to the porosity, conformational rigidity, and due to the presence of hydrazone and/or disulfide moieties that act as mechanophores. Therefore, during ball milling, 5 gets partially disintegrated at

• . Mechanochemical solid-state complexation of organic capsule 5 with fullerenes C70 in a planetary ball mill. Figure 6 was adapted from [65], H. Jędrzejewska et al., “Porous Molecular Capsules as Non- Polymeric Transducers of Mechanical Forces to Mechanophores”, Chem. Eur. J., with permission from John Wiley and

Heteroleptic metallosupramolecular aggregates/complexation for supramolecular catalysis

• Prodip Howlader and
• Michael Schmittel

Beilstein J. Org. Chem. 2022, 18, 597–630, doi:10.3762/bjoc.18.62

• chemistry and information science. Keywords: heteroleptic complexation; information science; supramolecular catalysis; switching catalysis; systems chemistry; Introduction Supramolecular catalysis [1][2][3] for most chemists is associated with a catalytically active capsule providing either activating

• hydride species 49 that is well known for hydroformylation reactions [77]. Incorporation of the monoligated catalyst into the confined cavity of the capsule showed very good catalytic activity towards the hydroformylation of styrene (50, Figure 11) with a high stereoselectivity (65% ee) at 32% conversion

• compared to the non-encapsulated catalyst, which only managed to yield 8% ee at 4% of conversion. Thus, the molecular capsule 47 can be viewed as a second coordination sphere of the catalyst, reminiscent of enzymatic active sites. In summary, the above discrete molecular architectures containing cavity and

A resorcin[4]arene hexameric capsule as a supramolecular catalyst in elimination and isomerization reactions

• Tommaso Lorenzetto,
• Fabrizio Fabris and
• Alessandro Scarso

Beilstein J. Org. Chem. 2022, 18, 337–349, doi:10.3762/bjoc.18.38

• Tommaso Lorenzetto Fabrizio Fabris Alessandro Scarso Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari di Venezia, via Torino 155, 30172, Mestre-Venezia, Italy 10.3762/bjoc.18.38 Abstract The hexameric resorcin[4]arene capsule as a self-assembled organocatalyst promotes a

• promoting the protonation of the substrates leading to the formation of cationic intermediates that are stabilized within the cavity with consequent peculiar features in terms of acceleration and product selectivity. In all cases the catalytic activity displayed by the hexameric capsule is remarkable if

• ] selectivity, the capsule attracted the attention of several other research groups bringing this self-assembled nanocontainer to the forefront in the field of supramolecular catalysts. The specific field of research has been recently reviewed [19][30][31][32][33] to underline the potentialities of this simple

Progress and challenges in the synthesis of sequence controlled polysaccharides

• Giulio Fittolani,
• Theodore Tyrikos-Ergas,
• Denisa Vargová,
• Manishkumar A. Chaube and
• Martina Delbianco

Beilstein J. Org. Chem. 2021, 17, 1981–2025, doi:10.3762/bjoc.17.129

Anion-driven encapsulation of cationic guests inside pyridine[4]arene dimers

• Anniina Kiesilä,
• Jani O. Moilanen,
• Anneli Kruve,
• Christoph A. Schalley,
• Perdita Barran and
• Elina Kalenius

Beilstein J. Org. Chem. 2019, 15, 2486–2492, doi:10.3762/bjoc.15.241

• to the electron-poor nature of the pyridine ring. Herein, we demonstrate the encapsulation of Me4N+ cations inside a dimeric hydrogen-bonded pyridine[4]arene capsule, which contradicts with earlier assumptions. The complexation of a cationic guest inside the pyridine[4]arene dimer has been detected

• + formed complexes with 1 and 12, neither using electrospray ionization (ESI) in the positive nor the negative mode. Pr4N+ is certainly too large to fit inside the dimeric capsule, whereas the other non-complexing cations are protic and – as rather strong hydrogen-bond donors – may interfere with

• , Supporting Information File 1). This ion further dissociates to a neutral monomer and to the [1 − 2H + Me4N]− ion, which can only result from two HA eliminations and dissociation of the H-bonded capsule. Elimination of two HA molecules and formation of [1 + Me4N − 2H]− would be unexpected from a complex with

Complexation of chiral amines by resorcin[4]arene sulfonic acids in polar media – circular dichroism and diffusion studies of chirality transfer and solvent dependence

• Bartosz Setner and
• Agnieszka Szumna

Beilstein J. Org. Chem. 2019, 15, 1913–1924, doi:10.3762/bjoc.15.187

• macrocyclic host, like hexameric resorcin[4]arene capsule, shows chirality induction from a chiral tertiary amine guest in deuterated chloroform [23]. Interestingly, there is a difference in the “degree” of guest-induced diastereomeric splitting of the host’s signal in the order 1(LysOMe)2 > 1(HisOMe)2 >> 1

• Information File 1). Capsule formation: Capsules formed between tetrakis(sulfonatomethyl)resorcin[4]arene 1 (11 mg, 0.01 mmol) and tetrakis((α)-methylbenzylaminomethyl)resorcin[4]arenes (R)-2 or (S)-2 (14 mg, 0.01 mmol) were prepared by dissolving in water (1 mL) and mixing two resorcin[4]arene derivative

Halogen bonding and host–guest chemistry between N-alkylammonium resorcinarene halides, diiodoperfluorobutane and neutral guests

• Fangfang Pan,
• Mohadeseh Dashti,
• Michael R. Reynolds,
• Kari Rissanen,
• John F. Trant and
• Ngong Kodiah Beyeh

Beilstein J. Org. Chem. 2019, 15, 947–954, doi:10.3762/bjoc.15.91

• nature of the halogen bond assembly. The crystal lattice of 1 contains two structurally different dimeric assemblies A and B, formally resulting in the mixture of a capsular dimer and a dimeric pseudo-capsule. 1H and 19F NMR analyses supports the existence of these halogen-bonded complexes and enhanced

• guest inclusion in solution. Keywords: capsule; dimeric assemblies; halogen bonding; host–guest chemistry; resorcinarene salts; X-ray crystallography; Introduction The construction of specific supramolecular assemblies based on the directional non-covalent bonding has been a central goal of

• tube, only creating isolated pores in the cavity of the resorcinarene. Note that the two modes are present simultaneously in the crystal lattice, thus, the structure formally contains around 75% halogen bonded dimer, and 25% halogen bonded capsule. Additionally, the conformation difference could reveal

Mechanochemistry of supramolecules

• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2019, 15, 881–900, doi:10.3762/bjoc.15.86

• capsule 40 formed through hydrogen-bonding and the cavity was found to be able to encapsulate different organic molecules such as alkanes, acids, amines, etc. The encapsulation of a [2.2]paracyclophane in the cage was achieved by ball milling at 30 Hz (Figure 22) and the host–guest product 40 was verified

Synthetic avenues towards a tetrasaccharide related to Streptococcus pneumonia of serotype 6A

• Aritra Chaudhury,
• Mana Mohan Mukherjee and
• Rina Ghosh

Beilstein J. Org. Chem. 2018, 14, 1095–1102, doi:10.3762/bjoc.14.95

• : Laboratory of Bioorganic Chemistry, NIH, NIDDK, Bethesda, MD, USA 10.3762/bjoc.14.95 Abstract Streptococcus pneumonia (SPn) is a Gram-positive bacterium which causes life threatening diseases. The bacteria protect themselves against non-specific host defence by an external polysaccharide (PS) capsule which

Hydroxy-functionalized hyper-cross-linked ultra-microporous organic polymers for selective CO₂ capture at room temperature

• Partha Samanta,
• Priyanshu Chandra and
• Sujit K. Ghosh

Beilstein J. Org. Chem. 2016, 12, 1981–1986, doi:10.3762/bjoc.12.185

• , a clear capsule-type of morphology was found in the FESEM (Figure 2d and Figure S6). After all characterizations and proper desolvation of both compounds, we investigated their porosity. First, we measured the N2 adsorption at 77 K. The N2 uptake for HCP-91 was found to be 595 mL/g, whereas that for

Organic chemistry meets polymers, nanoscience, therapeutics and diagnostics

• Vincent M. Rotello

Beilstein J. Org. Chem. 2016, 12, 1638–1646, doi:10.3762/bjoc.12.161

• proteins (transferrin) and cationic nanoparticles to create stable capsules [62]. These capsules delivered hydrophobic drugs and dyes to cells very effectively. A puzzling question arose however: dyes were delivered into cells much faster than the particles on the outside of the capsule. Clearly, endosomal

• made use of the oil interior of the capsule to provide dual protein (caspase 3) and therapeutic (paclitaxel) delivery where the two payloads worked synergistically for chemotherapy [65]. Being supramolecular types, we figured we could swap out the anionic proteins used above for anionic siRNA [66]. In

From steroids to aqueous supramolecular chemistry: an autobiographical career review

• Bruce C. Gibb

Beilstein J. Org. Chem. 2016, 12, 684–701, doi:10.3762/bjoc.12.69

• complexes in water. More importantly, because the pocket and rim of the host would be poorly solvated, in the presence of an apolar guest we envisioned the host would dimerize around it. In other words, we hoped that the hydrophobic effect, would drive capsule assembly. To our knowledge this represented an

• more importantly we wanted guests that were very hydrophobic and rigid. Our concern was – and this proved to be completely unfounded – that two octa-acids in a capsule would slip and slide all over each other. In other words, with a lack of what are traditionally viewed as functional groups that can

• exceedingly stable capsular complexes (Figure 6). Regarding their stability, even at 5 μM, NMR showed complete encapsulation of estradiol; giving a minimum apparent binding constant for the empty capsule (the host is actually monomeric in the absence of guests) of 1 × 108 M−1. When the steroid was very large

Elucidation of a masked repeating structure of the O-specific polysaccharide of the halotolerant soil bacteria Azospirillum halopraeferens Au4

• Elena N. Sigida,
• Yuliya P. Fedonenko,
• Alexander S. Shashkov,
• Nikolay P. Arbatsky,
• Evelina L. Zdorovenko,
• Svetlana A. Konnova,
• Vladimir V. Ignatov and
• Yuriy A. Knirel

Beilstein J. Org. Chem. 2016, 12, 636–642, doi:10.3762/bjoc.12.62

• of Sciences (IBPPM RAS, Saratov) and was cultivated under aerobic conditions at 41 °C in a liquid malate medium [8] supplemented with 0.09 M NaCl. In an analogous manner as described before [14][33] the cells were washed from the capsule and dried, LPS was extracted from the biomass (10 g) by the

Synthesis of uniform cyclodextrin thioethers to transport hydrophobic drugs

• Lisa F. Becker,
• Dennis H. Schwarz and
• Gerhard Wenz

Beilstein J. Org. Chem. 2014, 10, 2920–2927, doi:10.3762/bjoc.10.310

• signal and m for multiplet. Mass spectra were recorded by a LC–MS spectrometer ZQ-4000 from Waters GmbH, Eschborn, Germany, operated in ESI+ and ESI− mode. Some products were purified by cross-flow nanofiltration using a membrane called Mini Mate TPP Capsule from Pall, Crailsheim, Germany, further a

Novel supramolecular affinity materials based on (−)-isosteviol as molecular templates

• Christina Lohoelter,
• Malte Brutschy,
• Daniel Lubczyk and
• Siegfried R. Waldvogel

Beilstein J. Org. Chem. 2013, 9, 2821–2833, doi:10.3762/bjoc.9.317

• precursor all-syn-16 in hands and the need for organic materials with pronounced cavities as potent affinity materials we envisioned the synthesis of a capsule-type architecture. Therefore, all-syn-16 was O-alkylated by treatment with 5-bromo-1-pentene using standard conditions [70] to yield the

• corresponding triptycene derivative all-syn-17 (Scheme 7). Alkylation proceeded with a moderate yield of 31%. Equipped with three terminal alkenes all-syn-17 seems to be a suitable precursor for subsequent olefin metathesis to form a capsule-like structure. The structure of all-syn-17 was confirmed via X-ray

Inclusion of the insecticide fenitrothion in dimethylated-β-cyclodextrin: unusual guest disorder in the solid state and efficient retardation of the hydrolysis rate of the complexed guest in alkaline solution

• Dyanne L. Cruickshank,
• Natalia M. Rougier,
• Raquel V. Vico,
• Susan A. Bourne,
• Elba I. Buján,
• Mino R. Caira and
• Rita H. de Rossi

Beilstein J. Org. Chem. 2013, 9, 106–117, doi:10.3762/bjoc.9.14

• ]. A crystalline inclusion complex (TRIMEA)2·1 was isolated and shown by X-ray analysis to contain a novel capsule formed by head-to-head contact of the secondary rims of two TRIMEA molecules [5]. The encapsulated fenitrothion molecule showed minor disorder in the form of two rotamers (with respect to

Fifty years of oxacalix[3]arenes: A review

• Kevin Cottet,
• Paula M. Marcos and
• Peter J. Cragg

Beilstein J. Org. Chem. 2012, 8, 201–226, doi:10.3762/bjoc.8.22

• methyl or N,N-diethylamide groups, were coupled to mono-t-Boc-protected 1,4-xylylenediamine. Subsequent deprotection and reaction with a second equivalent of the oxacalixarene acid gave the dimeric compound (capsule-40) shown in Figure 13. A nonencapsulating analogue was prepared through reaction of the

• acid derivative with benzylamine. The overall yield from the oxacalix[3]arene is less than 5%, but, given that the dimerization proceeds in only 14%, this is nevertheless quite impressive. However, in addition to the formation of the molecular capsule, a self-threaded dimer (rotaxane-40) was also

• isolated, which had resulted from an upper-rim substituent threading through the central cavity during dimerization. The existence of the rotaxane structure was deduced from the complexity of the patterns observed in the 1H NMR spectrum compared to that of the capsule. A similar strategy was adopted to

On the mechanism of action of gated molecular baskets: The synchronicity of the revolving motion of gates and in/out trafficking of guests

• Keith Hermann,
• Stephen Rieth,
• Hashem A. Taha,
• Bao-Yu Wang,
• Christopher M. Hadad and
• Jovica D. Badjić

Beilstein J. Org. Chem. 2012, 8, 90–99, doi:10.3762/bjoc.8.9

• hosts, however, the slippage, gating and possible partial or full disassembly of the capsule constitute mechanistic alternatives for the exchange of guests [4]. In the last decade, we [9][10][11][12][13][14] and others [7][8][15][16][17][18] have studied gated molecular encapsulation in artificial and

Advances in synthetic approach to and antifungal activity of triazoles

• Kumari Shalini,
• Nitin Kumar,
• Sushma Drabu and
• Pramod Kumar Sharma

Beilstein J. Org. Chem. 2011, 7, 668–677, doi:10.3762/bjoc.7.79

• strain-dependent fungicidal activity against filamentous fungi with the exception of some strains of Cryptococcus neoformans. It is taken orally in capsule form to treat fungal infections that start in the lungs and spread throughout the body. Itraconazole can also be used to treat fungal infections of