Cyclodextrin-based rotaxanes for polymer materials: challenge on simultaneous realization of inexpensive production and defined structures

• Yosuke Akae

Beilstein J. Org. Chem. 2024, 20, 3026–3049, doi:10.3762/bjoc.20.252

• substituted benzene ring, and γ-CD can host further bigger guest molecules, such as pyrene or two aliphatic chains, in one cavity. The ability of CD to form an inclusion complex structure is drastically affected by the cavity size or the modification strategy for the hydroxy groups on CD. To evaluate the

• formation of this inclusion complex, circular dichroism spectroscopy represents a powerful tool when combined with nuclear magnetic resonance (NMR) and X-ray single-crystal analysis. This is because the induced circular dichroism (ICD) can be observed on the guest molecule of the inclusion complex derived

• methods are more popular than the slipping method. However, this end-capping method must fulfill the following seven points to appropriately realize a rotaxane framework, and this causes several complexities (Figure 3): (1) The axle molecule must form a stable inclusion complex with CD, (2) the axle

Deciphering the mechanism of γ-cyclodextrin’s hydrophobic cavity hydration: an integrated experimental and theoretical study

• Stiliyana Pereva,
• Stefan Dobrev,
• Tsveta Sarafska,
• Valya Nikolova,
• Silvia Angelova,
• Tony Spassov and
• Todor Dudev

Beilstein J. Org. Chem. 2024, 20, 2635–2643, doi:10.3762/bjoc.20.221

• Sciences, 1113 Sofia, Bulgaria, University of Chemical Technology and Metallurgy, 8 St. Kliment Ohridski Blvd, 1756 Sofia, Bulgaria 10.3762/bjoc.20.221 Abstract Cyclodextrins (CDs) are host systems with inherent capability for inclusion complex formation with various molecular entities, mostly hydrophobic

• sides, unlike the internal cavity, are hydrophilic, decorated with primary (narrow rim) and secondary (wider rim) hydroxy groups. Van der Waals (vdW) and hydrophobic interactions have been identified as the main driving forces for CDs inclusion complex formation [2][3][4]. Electrostatic interactions and

• placement/locality of these water molecules in α-, β-, and γ-CDs is a matter of continuing debate. The water ligands could be coordinated inside the cavity or around either rim. Note that CDs retain some water molecules (numbers and position depending on the nature of the guest molecule) after the inclusion

Cyclodextrins permeabilize DPPC liposome membranes: a focus on cholesterol content, cyclodextrin type, and concentration

• Ghenwa Nasr,
• Hélène Greige-Gerges,
• Sophie Fourmentin,
• Abdelhamid Elaissari and
• Nathalie Khreich

Beilstein J. Org. Chem. 2023, 19, 1570–1579, doi:10.3762/bjoc.19.115

• ) was able to form two types of soluble complexes, with molar ratios of 1:1 and 1:2 (CHOL/DOM-β-CD). The latter (1:2 inclusion complex) occurred much more easily than that of the 1:1 complex showing a much higher equilibrium constant. At low CDs concentration, the formation of the 1:1 inclusion complex

• dominated with low equilibrium constant (109 M−1) suggesting that the unstable complex would rapidly decompose into its components. With time elapsing and with increasing CDs concentration, the 1:1 inclusion complex was transformed into the more stable 1:2 complex with greater equilibrium constant (5.68

CO₂ complexation with cyclodextrins

• Cecilie Høgfeldt Jessen,
• Jesper Bendix,
• Theis Brock Nannestad,
• Heloisa Bordallo,
• Martin Jæger Pedersen,
• Christian Marcus Pedersen and
• Mikael Bols

Beilstein J. Org. Chem. 2023, 19, 1021–1027, doi:10.3762/bjoc.19.78

• split over two positions yielding in total 5.75 mol of water per CO2. The hydration is similar to that of native α-CD [13] and that of the krypton inclusion complex which has 5.28 water/Kr [14]. The CO2 molecule refines with an optimal occupancy of 0.84 and linear geometry (178.2(6)o) with C–O bond

Cyclodextrins as building blocks for new materials

• Miriana Kfoury and
• Sophie Fourmentin

Beilstein J. Org. Chem. 2023, 19, 889–891, doi:10.3762/bjoc.19.66

• containing CDs. Three clinical trials have demonstrated the use of CDs in the treatment of COVID-19. Two of them use the sulfobutyl ether β-CD/remdesivir inclusion complex and the third applies the α-CD/sulforaphane inclusion complex called Sulforadex® [6]. The approved Janssen vaccine against SARS-CoV-2

A fluorescent probe for detection of Hg²⁺ ions constructed by tetramethyl cucurbit[6]uril and 1,2-bis(4-pyridyl)ethene

• Xiaoqian Chen,
• Naqin Yang,
• Yue Ma,
• Xinan Yang and
• Peihua Ma

Beilstein J. Org. Chem. 2023, 19, 864–872, doi:10.3762/bjoc.19.63

• that TMeQ[6] and G form an inclusion complex with a host–guest ratio of 1:1 and the equilibrium association constant (Ka) was 2.494 × 104 M−1. The G@TMeQ[6] fluorescent probe can sensitively recognize Hg2+ ions by fluorescence enhancement. The linear range is 0.33 × 10−5–1.65 × 10−5 mol·L−1, R2

• that a G and TMeQ[6] inclusion complex is formed with a 1:1 stoichiometry. Isothermal titration calorimetry (ITC) analysis The association constant and thermodynamic parameters of the host–guest interaction between G and TMeQ[6] can be obtained using ITC. At 25 °C, a neutral aqueous solution of TMeQ[6

• structure of the inclusion complex formed by TMeQ[6] and G was obtained using X-ray single-crystal diffraction analysis. The crystal data and parameters are shown in Table 2. The single-crystal structure determination shows that the inclusion complex crystallizes in the triclinic crystal system, with the

pH-Responsive fluorescent supramolecular nanoparticles based on tetraphenylethylene-labelled chitosan and a six-fold carboxylated tribenzotriquinacene

• Nan Yang,
• Yi-Yan Zhu,
• Wei-Xiu Lin,
• Yi-Long Lu and
• Wen-Rong Xu

Beilstein J. Org. Chem. 2023, 19, 635–645, doi:10.3762/bjoc.19.45

• value when the concentration of CS-TPE-2% was 48 µg/mL, where a simple inclusion complex formed between TBTQ-C6 and CS-TPE-2%. As a result, the optimal mixing ratio for the formation of TBTQ-C6/CS-TPE-2% supra-amphiphilic assembly is 0.10 mM TBTQ-C6 + 48 µg/mL CS-TPE-2%. Analogously, the optimal mixing

Discrimination of β-cyclodextrin/hazelnut (Corylus avellana L.) oil/flavonoid glycoside and flavonolignan ternary complexes by Fourier-transform infrared spectroscopy coupled with principal component analysis

• Nicoleta G. Hădărugă,
• Gabriela Popescu,
• Dina Gligor (Pane),
• Cristina L. Mitroi,
• Sorin M. Stanciu and
• Daniel Ioan Hădărugă

Beilstein J. Org. Chem. 2023, 19, 380–398, doi:10.3762/bjoc.19.30

• cheap method for the evaluation of quality and similarity/characteristics of these new types of cyclodextrin-based ternary complexes having enhanced properties and stability. Keywords: antioxidant; cyclodextrin; flavonoid; hazelnut vegetable oil; ternary supramolecular inclusion complex; Introduction

• the co-precipitation from a saturated solution. The peony oil content in the complex was almost 26%, with a high ratio of unsaturated FA glycerides of ≈90% [20]. In a very recent study, perilla (Perilla frutescens (L.) Britton) seed oil was complexed by γ-CD and the inclusion complex was used for

CuAAC-inspired synthesis of 1,2,3-triazole-bridged porphyrin conjugates: an overview

• Dileep Kumar Singh

Beilstein J. Org. Chem. 2023, 19, 349–379, doi:10.3762/bjoc.19.29

• 126, it was used to form water-soluble porphyrin nanospheres by self-inclusion complex formation in water. Tritriazole-bridged porphyrin system This section contains the synthesis of porphyrin conjugates having three 1,2,3-triazole groups as linkers. In 2012, Beletskaya and co-workers [55] described

• , Jayawickramarajah and co-workers [69] synthesized a water-soluble porphyrin-fullerene (C60) nanorod through the formation of an inclusion complex between an octa(permethylated-β-CD)-Zn-porphyrin 174 and a pristine C60. For the construction of the nanorod, porphyrin 174 was first obtained in 65% yield by a Cu(I

Inclusion complexes of the steroid hormones 17β-estradiol and progesterone with β- and γ-cyclodextrin hosts: syntheses, X-ray structures, thermal analyses and API solubility enhancements

• Alexios I. Vicatos,
• Zakiena Hoossen and
• Mino R. Caira

Beilstein J. Org. Chem. 2022, 18, 1749–1762, doi:10.3762/bjoc.18.184

• cm3·min−1. All DSC experiments were terminated prior to the decomposition of each sample. Solubility analysis by gravimetric increments A gravimetric solubility approach was used involving the addition of small, accurately pre-weighed incremental amounts of a given CD inclusion complex (total mass

• approximately 30 mg each) into a vial containing 3 cm3 of water. A visual estimation of the solubility was established after the final suspension was stirred for 72 hours at 27 °C. This procedure ensured that a very narrow solubility range was spanned by the penultimate and final incremental CD inclusion

• complex additions, the final amount resulting in saturation of the solution. The apparatus involved a Radleys Standard stirring hotplate with a 2.5 cm high vial supporting stand attached to it. The vials were placed on the stand in a circle at a radius of 4 cm from the centre, and the solutions were

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

• effective values for the sum of all interaction steps. Although from the sole ITC experiment, the formation of tetracene inclusion complex with CDs can't be affirmed, the observed stoichiometry favors this hypothesis. Additionally, the binding strength in terms of Ka (M−1) well matches the solubility

Cyclodextrin-based Schiff base pro-fragrances: Synthesis and release studies

• Attila Palágyi,
• Jindřich Jindřich,
• Juraj Dian and
• Sophie Fourmentin

Beilstein J. Org. Chem. 2022, 18, 1346–1354, doi:10.3762/bjoc.18.140

• hydrophilic outer surface and hydrophobic cavity. This cavity can encapsulate another lipophilic guest molecule and thus form an inclusion complex [3][4]. This phenomenon is reversible and leads to an equilibrium between encapsulated and free guest. A staggering number of inclusion complexes of CDs with

Tetraphenylethylene-embedded pillar[5]arene-based orthogonal self-assembly for efficient photocatalysis in water

• Zhihang Bai,
• Krishnasamy Velmurugan,
• Xueqi Tian,
• Minzan Zuo,
• Kaiya Wang and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2022, 18, 429–437, doi:10.3762/bjoc.18.45

• G guest molecule were involved in the inclusion complex and further self-assembled to form worm-like supramolecular nanostructures, which displayed an AIE effect via restricted phenyl-ring rotation of m-TPEWP5. After that, the negative EsY acceptor was loaded on the positively charged surface of the

1,2-Naphthoquinone-4-sulfonic acid salts in organic synthesis

• Ruan Carlos B. Ribeiro,
• Patricia G. Ferreira,
• Amanda de A. Borges,
• Luana da S. M. Forezi,
• Fernando de Carvalho da Silva and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 53–69, doi:10.3762/bjoc.18.5

• recognition of cholylglycine, which is a combination of cholic acid and glycine. The β-cyclodextrin/graphene oxide composite forms an inclusion complex with a β-NQS guest. The amino group of cholylglycine can bind to β-NQS by a nucleophilic substitution reaction, resulting in a decrease in the electrochemical

Host–guest interaction and properties of cucurbit[8]uril with chloramphenicol

• Lin Zhang,
• Jun Zheng,
• Guangyan Luo,
• Xiaoyue Li,
• Yunqian Zhang,
• Zhu Tao and
• Qianjun Zhang

Beilstein J. Org. Chem. 2021, 17, 2832–2839, doi:10.3762/bjoc.17.194

• Q[8] formed a 1:1 inclusion complex (CPE@Q[8]) with an inclusion constant of 5.474 × 105 L/mol. The intervention of Q[8] did not affect the stability of CPE, but obviously reduced the release rate of CPE in artificial gastric and intestinal juice; Q[8] has a slow-release effect on CPE. The

• in water and has a bitter taste. Upon forming an inclusion complex with cyclodextrin, the solubility and bitter taste of CPE can be improved [4][5]. Ramesh Gannimani et al. [6] reported that the inclusion complex of cyclodextrin and CPE loaded silver nanoparticles possessed stronger antibacterial

• and carbon atoms and the cavity has a certain degree of hydrophobicity that can form a stable host–guest inclusion complex with a guest molecule via non-bonding interactions, such as hydrogen bonds, van der Waals forces and ionic dipoles [21][22][23][24][25][26][27][28]. It has been proved that

Host–guest interaction of cucurbit[8]uril with oroxin A and its effect on the properties of oroxin A

• Zhishu Zeng,
• Jun Xie,
• Guangyan Luo,
• Zhu Tao and
• Qianjun Zhang

Beilstein J. Org. Chem. 2020, 16, 2332–2337, doi:10.3762/bjoc.16.194

• the inclusion compound with Q[8]. Keywords: cucurbit[8]uril; host–guest interaction; inclusion complex; oroxin A; properties; Introduction Cucurbit[n]urils (Q[n]s) are a family of macrocyclic cage compounds synthesized by the condensation of glycoluril and formaldehyde in a strong acidic solution [1

• in the case of an excess of OA, the port interactions and inclusion interactions of OA andQ[8] can exist simultaneously. To further determine the host–guest ratio of the inclusion complex formed by Q[8] and OA, their interaction was investigated using UV–visible absorption spectroscopy via a molar

• mode (Figure 3B). Figure 4 shows the IR spectra recorded for Q[8] (a), OA (b), a physical mixture of Q[8] and OA (n(Q[8]):n(OA) = 1:1) (c) and the OA@Q[8] inclusion complex (d). Curve (c) contains characteristic peaks of curves (a) and (b) without interaction in the physical mixture. Comparing spectra

Mechanochemical green synthesis of hyper-crosslinked cyclodextrin polymers

• Alberto Rubin Pedrazzo,
• Fabrizio Caldera,
• Marco Zanetti,
• Silvia Lucia Appleton,
• Nilesh Kumar Dhakar and
• Francesco Trotta

Beilstein J. Org. Chem. 2020, 16, 1554–1563, doi:10.3762/bjoc.16.127

• were obtained only with βNS-CDI 1:8. Even in case of βNS-CDI 1:8, if treated for 8 h in H2O at 40 °C (0.40% N), presented a low amount (≈0) of reactive IM, therefore the reaction did not occur at all, leading only to an inclusion complex with the dyes, which could be easily removed through a PS

[3 + 2] Cycloaddition with photogenerated azomethine ylides in β-cyclodextrin

• Margareta Sohora,
• Leo Mandić and
• Nikola Basarić

Beilstein J. Org. Chem. 2020, 16, 1296–1304, doi:10.3762/bjoc.16.110

• azomethyine ylides, giving formal 1,4 H-shifted products. Thus, in the presence of H2O, no cycloaddition products are anticipated. However, it should be probed if the [3 + 2] cycloaddition can compete with the 1,4 H-shift upon irradiation of an inclusion complex. Under our conditions, photodecarboxylation of

• of the phthalimide, which changed from a singlet to a multiplet (Figure S1 in Supporting Information File 1). The spectral changes are in accordance with the formation of an inclusion complex 2@β-CD, with the dynamics for the complexation faster than the NMR time-scale (millisecond). Nonlinear

• regression analysis of the chemical shifts depending on the β-CD concentration, to a complexation model with 1:1 stoichiometry, showed good correlation (Figure 2 and Figure S2 in Supporting Information File 1), with the stability constant for 2@β-CD K = 190 ± 50 M−1. Formation of the inclusion complex was

The interaction between cucurbit[8]uril and baicalein and the effect on baicalein properties

• Xiaodong Zhang,
• Jun Xie,
• Zhiling Xu,
• Zhu Tao and
• Qianjun Zhang

Beilstein J. Org. Chem. 2020, 16, 71–77, doi:10.3762/bjoc.16.9

• corresponding properties of the inclusion complex were studied using 1H NMR, IR and UV–vis spectroscopy and DTA. The results showed that BALE forms an inclusion compound (1:1) with Q[8], and the properties of baicalein are changed by cucurbit[8]uril. Keywords: baicalein; cucurbit[8]uril; host–guest interaction

• ; inclusion complex; properties; Introduction Baicalein (5,6,7-trihydroxyflavonoid) has a molecular formula of C15H10O5 (BALE, Figure 1) and is a natural flavonoid found in the roots of Scutellaria baicalensis Georgi [1]. The compound displays pharmacological activity such as antimicrobial, anti-inflammatory

• compounds such as calixarenes, crown ethers and cyclodextrins, which can be used to form a stable inclusion complex with the drug, and improving the bioavailability of the drug [34][35]. Herein, we describe the results of the investigations of host–guest interactions between BALE and Q[8] in an aqueous

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

• switching to the Z isomer was accompanied by the release of one of the two guests from the cage and the formation of a 1:1 cage/Z-arylazopyrazole inclusion complex. DFT calculations suggest that this process involves a dramatic change in the conformation of the cage. Back-isomerization was induced with

• ; the strongest correlations were found between Ha and H1 and between Hc and H4 (Figure S20, Supporting Information File 1; note that the opposite was found for the E isomer, cf. Figure 2). Despite repeated efforts, we did not succeed in preparing crystals of the (Z-1)2 inclusion complex suitable for X

• –guest inclusion complex incorporating two molecules of arylazopyrazole was obtained in a quantitative yield. The complex was characterized by a series of NMR techniques, which showed that the resonances of the guest protons were upfield-shifted by up to 2.2 ppm. An antiparallel configuration of the

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

• . Although the hydrophobic biphenylene is expected to form a more stable inclusion complex with γ-CD due to a stronger hydrophobic effect, a structure with the γ-CD interlocking at the central biphenylene of 4R may not explain the non-equivalent chemical environments of the two termini. As discussed in the

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

• and TΔS = −21.66 kJ·mol−1 for inclusion complex G1·host-1; ΔH = −65.77 kJ·mol−1 and TΔS = −26.46 kJ·mol−1 for the inclusion complex G2·host-1; ΔH = −39.01 kJ·mol−1 and TΔS = −1.02 kJ·mol−1 for the inclusion complex G1·host-2); while only the formation of the inclusion complexes of host-2 with G2 is

Host–guest interactions between p-sulfonatocalix[4]arene and p-sulfonatothiacalix[4]arene and group IA, IIA and f-block metal cations: a DFT/SMD study

• Valya K. Nikolova,
• Cristina V. Kirkova,
• Silvia E. Angelova and
• Todor M. Dudev

Beilstein J. Org. Chem. 2019, 15, 1321–1330, doi:10.3762/bjoc.15.131

• anchoring points for the positively charged guests. Cation–π interactions between the monoatomic cations and p-sulfonatocalix[4]arene in water are supposed (but not proven) to take part in the inclusion complex formation [31]. Mendes et al. have carried out molecular dynamics (MD) simulations of association

• the SO3 belt (common structural unit for both molecules) which is far away from the structurally different methylene/sulfur bridges at the lower rim. Water solvation has great impact on the Gibbs energies of the complex formation. The process of inclusion complex formation in aqueous solution becomes

Precious metal-free molecular machines for solar thermal energy storage

• Meglena I. Kandinska,
• Snejana M. Kitova,
• Vladimira S. Videva,
• Stanimir S. Stoyanov,
• Stanislava B. Yordanova,
• Stanislav B. Baluschev,
• Silvia E. Angelova and
• Aleksey A. Vasilev

Beilstein J. Org. Chem. 2019, 15, 1096–1106, doi:10.3762/bjoc.15.106

• constant was found to be K = 70 ± 15 M−1 which is in good correlation with the published data [22]. These results prompted us to identify the optimal Ba2+ concentration, necessary for a maximum degree of dye–Ba2+ inclusion complex formation. Obviously for a better complexation it is necessary to work with

Fabrication of supramolecular cyclodextrin–fullerene nonwovens by electrospinning

• Hiroaki Yoshida,
• Ken Kikuta and
• Toshiyuki Kida

Beilstein J. Org. Chem. 2019, 15, 89–95, doi:10.3762/bjoc.15.10

• introducing functional groups into the molecule directly. Among them, the formation of a 2:1 inclusion complex of γ-CD and C60 has been evaluated in various solvents such as water [21], toluene/water [22], DMSO [23], and DMF/water [24]. Although an impressive report that a 2:1 complex in water can be utilized

• realizes easy handling of inclusion complexation with guest molecules as well as electrospinning due to the much lower viscosity of the CD/HFIP solution. The formation of a 2:1 inclusion complex should not affect the solution properties (e.g., viscosity and solubility), but should provide electrospinning

• parameters similar to the case without the guest because the guest molecule is isolated from the solvent molecules by two γ-CD molecules. This is in contrast with the part of the guest molecule uncovered by γ-CD which may interact with the solvent molecules in the case of a 1:1 inclusion complex. Moreover