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

• host–guest complexation, it can also only bind to coordinating guests (terpyridine, bipyridine) due to the proximity of the coordination sphere with the binding pocket. Tweezers 11 with NDI arms and an extended pyridine-hydrazone-pyridine-hydrazone-pyridine switchable unit have thus been developed

Enhanced host–guest interaction between [10]cycloparaphenylene ([10]CPP) and [5]CPP by cationic charges

• Eiichi Kayahara,
• Yoshiyuki Mizuhata and
• Shigeru Yamago

Beilstein J. Org. Chem. 2024, 20, 436–444, doi:10.3762/bjoc.20.38

• ) [31]. The increased Ka is most likely attributed to the ionic interaction caused by the presence of the cationic species, as will be discussed below. To clarify the effect of the polar interaction, the host–guest complexation was studied in a polar solvent, such as nitrobenzene and acetonitrile

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

• host–guest complexation, as a consequence of a mutual-induced fit of host and guest molecules [39]. With reference to γ-CD·PRO, the asymmetric unit (ASU) comprises three pairs of glucose rings that generate three complete γ-CD molecules when rotation of these units around the four-fold axis parallel to

Synthesis of a new water-soluble hexacarboxylated tribenzotriquinacene derivative and its competitive host–guest interaction for drug delivery

• Man-Ping Li,
• Nan Yang and
• Wen-Rong Xu

Beilstein J. Org. Chem. 2022, 18, 539–548, doi:10.3762/bjoc.18.56

• synthesized compounds were fully characterized by 1H and 13C NMR spectroscopy and mass spectrometry (see Supporting Information File 1) and the data were found to be consistent with the proposed structures. Host–guest complexation of TBTQ-CB6 with dimethyl viologen (MV). The host–guest complexation between

• -rich cavity of TBTQ-CB6 [32]. In addition, the proton resonances became broadened caused by the complexation dynamics, indicating the successful host–guest complexation between TBTQ-CB6 and MV. Subsequently, the association stoichiometry of the complex was studied by the Job plot method using

• association constant was determined to be Ka = (7.67 ± 0.34) × 104 M−1 by nonlinear curve fitting [33] (Figure 1d). Host–guest complexation of TBTQ-CB6 with doxorubicin (DOX). The host–guest complexation between TBTQ-CB6 and DOX was studied by methods similar to those used for TBTQ-CB6 and MV. The 1H NMR

Insight into functionalized-macrocycles-guided supramolecular photocatalysis

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

Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15

• structural rigidity caused by supramolecular host–guest complexation, ii) that a restricted space, size, and volume could lead to three-dimensional translation (rotation, vibration, and translation) of the guests within the host cavities, and iii) the dynamic properties of the guest within the supramolecular

• , Yagi, et al. reported that the visible-light-driven hydrogen evolution of the supramolecular system could be achieved by the host–guest complexation between the cobaloxime CoPyS and γ-CD (Figure 10) [30]. Upon visible-light irradiation, the CoPyS:γ-CD 1:1 complex exhibited an enhanced photocatalytic H2

Construction of pillar[4]arene[1]quinone–1,10-dibromodecane pseudorotaxanes in solution and in the solid state

• Xinru Sheng,
• Errui Li and
• Feihe Huang

Beilstein J. Org. Chem. 2020, 16, 2954–2959, doi:10.3762/bjoc.16.245

• 450001, P. R. China 10.3762/bjoc.16.245 Abstract We report novel pseudorotaxanes based on the complexation between pillar[4]arene[1]quinone and 1,10-dibromodecane. The complexation is found to have a 1:1 host–guest complexation stoichiometry in chloroform but a 2:1 host–guest complexation stoichiometry

• reports [44][45]. We found that H and G can be used to build a [3]pseudorotaxane in the solid state but a [2]pseudorotaxane in solution. Results and Discussion Host–guest complexation in the solid state Cocrystals of H and G were obtained by slow evaporation of the solution in methanol. The X-ray

• the hydrogen atoms on the ethoxy groups. It is worth mentioning that we did not find any interaction of the benzoquinone subunit of the host with the guest molecule. Host–guest complexation in solution In order to further study the host–guest binding properties of H and G, we explored the complexation

Water-soluble host–guest complexes between fullerenes and a sugar-functionalized tribenzotriquinacene assembling to microspheres

• Si-Yuan Liu,
• Xin-Rui Wang,
• Man-Ping Li,
• Wen-Rong Xu and
• Dietmar Kuck

Beilstein J. Org. Chem. 2020, 16, 2551–2561, doi:10.3762/bjoc.16.207

• detail by NMR spectroscopy and mass spectrometry. The host–guest complexation of TBTQ-(OG)6 with C60 and C70 takes place in a 1:1 molar ratio in both cases and with association constants of Ka = (1.50 ± 0.10) × 105 M−1 and Ka = (2.20 ± 0.16) × 105 M−1, respectively. It is suggested that the formation of

Synthesis and anion binding properties of phthalimide-containing corona[6]arenes

• Meng-Di Gu,
• Yao Lu and
• Mei-Xiang Wang

Beilstein J. Org. Chem. 2019, 15, 1976–1983, doi:10.3762/bjoc.15.193

• noncovalent interactions between anions and the tetrazine rings. Keywords: anion–π interactions; coronarenes; host–guest complexation; N-functionalized phthalimides; O6-corona[3]arene[3]tetrazines; Introduction Synthetic macrocycles [1][2] are always attractive and important because they are unique

Complexation of 2,6-helic[6]arene and its derivatives with 1,1′-dimethyl-4,4′-bipyridinium salts and protonated 4,4'-bipyridinium salts: an acid–base controllable complexation

• Jing Li,
• Qiang Shi,
• Ying Han and
• Chuan-Feng Chen

Beilstein J. Org. Chem. 2019, 15, 1795–1804, doi:10.3762/bjoc.15.173

• ; macrocycles; macrocyclic arene; Introduction Macrocyclic host molecules [1][2] play a significant role in host–guest chemistry. Compared with noncyclic molecules, the structures of macrocyclic hosts can greatly enhance the host–guest complexation ability through preorganization. Moreover, cyclic structures

•  1, Figures S1–S8). Host–guest complexation in solution Firstly, we tested the complexation between hosts H1 and H4 with guest G1 in solution by 1H NMR spectroscopy. As shown in Figure 2, when mixing equivalent amounts of host and guest in CDCl3/acetone-d6 1:2 (v/v), the 1H NMR spectrum showed a new

• binding abilities with helic[6]arene H1 and its derivatives H2–5. It is known that ion-pairing effects can hamper the complexation of charged species [41][42][43], and thus affect the host–guest complexation [10][44][45]. Consequently, we also prepared the 4,4'-bipyridinium salts G2 and G4 with BArF− as

Synthesis, enantioseparation and photophysical properties of planar-chiral pillar[5]arene derivatives bearing fluorophore fragments

• Guojuan Li,
• Chunying Fan,
• Guo Cheng,
• Wanhua Wu and
• Cheng Yang

Beilstein J. Org. Chem. 2019, 15, 1601–1611, doi:10.3762/bjoc.15.164

• guest receptors [4][5]. Planar-chiral macrocyclic molecules are particularly interesting in the context of the host–guest complexation properties [6][7][8]. Pillararenes are typical examples of this type of compounds and have attracted considerable attention due to their facile chemical synthesis and

Complexation of a guanidinium-modified calixarene with diverse dyes and investigation of the corresponding photophysical response

• Yu-Ying Wang,
• Yong Kong,
• Zhe Zheng,
• Wen-Chao Geng,
• Zi-Yi Zhao,
• Hongwei Sun and
• Dong-Sheng Guo

Beilstein J. Org. Chem. 2019, 15, 1394–1406, doi:10.3762/bjoc.15.139

• and potential applications according to the diverse photophysical responses are provided. Keywords: calixarene; host–guest complexation; luminescent dyes; macrocycles; photophysical properties; Introduction Fluorescence sensing represents a powerful detection methodology due to its low cost, ease of

• activation (BDA) [27]. In that work, we employed the four PSs and studied their host–guest complexation with GC5A. Each PS has a strong binding affinity upon 1:1 complexation with GC5A (Table 1), accompanied by a drastic annihilation of both fluorescence and photoactivity (reactive oxygen species generation

• luminescence alternation was observed upon gradual addition of GC5A to the Ru(dcbpy)3 solution (Figure 4a). The absorption of the MLCT band in the visible region was slightly altered by GC5A (Figure 4b). We therefore employed a competitive fluorescence titration to investigate the host–guest complexation

Mechanochemistry of supramolecules

• Anima Bose and
• Prasenjit Mal

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

• by NMR as well as other spectroscopic techniques. Georghiou et al. demonstrated the mechanochemical formation of a 1:1 supramolecular complex C60–tert-butylcalix[4]azulene 41 (Figure 23). The host–guest complexation was achieved by simple grinding the individual compounds in a mortar and pestle [95

Synthesis of a water-soluble 2,2′-biphen[4]arene and its efficient complexation and sensitive fluorescence enhancement towards palmatine and berberine

• Xiayang Huang,
• Xinghua Zhang,
• Tianxin Qian,
• Junwei Ma,
• Lei Cui and
• Chunju Li

Beilstein J. Org. Chem. 2018, 14, 2236–2241, doi:10.3762/bjoc.14.198

• as bioimaging and self-assembled drug delivery systems [33][34][35][36][37][38][39][40]. For example, our group demonstrated a direct host–guest complexation-based drug delivery system for oxaliplatin by carboxylatopillar[6]arene [36]. The encapsulation could not only improve the drug‘s stability in

• experiments of P and B with 2,2’-CBP4 in deuterated phosphate buffer (pD 7.4) were carried out to examine the host–guest complexation (Figure 1 and Figure S9 in Supporting Information File 1). From Figure 1, upon addition of the host, all the peaks of alkaloid B displayed upfield shifts and broadening

Dynamic light scattering studies of the effects of salts on the diffusivity of cationic and anionic cavitands

• Anthony Wishard and
• Bruce C. Gibb

Beilstein J. Org. Chem. 2018, 14, 2212–2219, doi:10.3762/bjoc.14.195

• regards to the former, we have shown how poorly solvated anions such as SCN− have an affinity for non-polar surfaces. Because of this, they can compete with the interactions between two non-polar surfaces in a host–guest complexation event and can induce an apparent weakening of the hydrophobic effect

An amphiphilic pseudo[1]catenane: neutral guest-induced clouding point change

• Tomoki Ogoshi,
• Tomohiro Akutsu and
• Tada-aki Yamagishi

Beilstein J. Org. Chem. 2018, 14, 1937–1943, doi:10.3762/bjoc.14.167

• point was observed upon addition of 1,4-dicyanobutane to an aqueous solution of 1 (Figure 3b, indicating that the hydrophobic/hydrophilic ratio did not change much by the host–guest complexation between 1 and 1,4-dicyanobutane because 1,4-dicyanobutane was hidden inside the hydrophilic pillar[5]arene

Strong binding and fluorescence sensing of bisphosphonates by guanidinium-modified calix[5]arene

• Jie Gao,
• Zhe Zheng,
• Lin Shi,
• Si-Qi Wu,
• Hongwei Sun and
• Dong-Sheng Guo

Beilstein J. Org. Chem. 2018, 14, 1840–1845, doi:10.3762/bjoc.14.157

• recovery, offers the opportunity for fluorescence “switch-on” sensing of BPs. In general, fluorescent IDA could be operated at low μM or even nM concentrations, which is desirable with respect to sensing sensitivity. We tested the host–guest complexation of GC5A with a total number of 9 BP drugs clinically

Host–guest complexes of conformationally flexible C-hexyl-2-bromoresorcinarene and aromatic N-oxides: solid-state, solution and computational studies

• Rakesh Puttreddy,
• Ngong Kodiah Beyeh,
• S. Maryamdokht Taimoory,
• Daniel Meister,
• John F. Trant and
• Kari Rissanen

Beilstein J. Org. Chem. 2018, 14, 1723–1733, doi:10.3762/bjoc.14.146

• :1 v/v, no significant chemical shift changes were observed for nine of the twelve pyridine N-oxides. The above results clearly show the strong influence of DMSO in interfering with the host–guest complexation between BrC6 and the aromatic N-oxides. However, with guests such as 5 and 9, endo cavity

A conformationally adaptive macrocycle: conformational complexity and host–guest chemistry of zorb[4]arene

• Liu-Pan Yang,
• Song-Bo Lu,
• Arto Valkonen,
• Fangfang Pan,
• Kari Rissanen and
• Wei Jiang

Beilstein J. Org. Chem. 2018, 14, 1570–1577, doi:10.3762/bjoc.14.134

• 1:1 mixture of ZB4 with 4+ or 5+ (Figures S1 and S2 in Supporting Information File 1). This indicates the importance of the core quaternary ammonium ions in the host−guest complexation. All other guests can be encapsulated in the cavity of ZB4, and significant chemical shifts on both the guests and

β-Cyclodextrin- and adamantyl-substituted poly(acrylate) self-assembling aqueous networks designed for controlled complexation and release of small molecules

• Liang Yan,
• Duc-Truc Pham,
• Philip Clements,
• Stephen F. Lincoln,
• Jie Wang,
• Xuhong Guo and
• Christopher J. Easton

Beilstein J. Org. Chem. 2017, 13, 1879–1892, doi:10.3762/bjoc.13.183

• PAAβ-CDen alone provides insight into the factors affecting dye complexation. The rates of release of the dyes through a dialysis membrane from the three aqueous networks show a high dependence on host–guest complexation between the β-CDen substituents and the dyes as well as the structure and the

• substitution of PAAβ-CDen. Thus, when host–guest complexation between the poly(acrylate) substituents of the network is complete, ca. two thirds of the β-CDen substituents remain available to complex other hydrophobic species exemplified by the dyes methyl red, MR, methyl orange, MO, and ethyl orange, EO

• (acrylate) networks as exemplified by the PAAβ-CDen/PAAADen system according to Equation 1. The complexation constant, K, for the host–guest complexation between the β-CDen and ADen substituents within the network is given by Equation 2. The data for the titration of a PAAβ-CDen solution into a PAAADen, a

A self-assembled cyclodextrin nanocarrier for photoreactive squaraine

• Ulrike Kauscher and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2016, 12, 2535–2542, doi:10.3762/bjoc.12.248

• aqueous solution of the vesicle [30]. The hydrophobic cyclodextrin cavities are well known to form size-selective inclusion complexes with apolar compounds such as adamantane [31]. In several publications, we have shown that CDVs retain this ability by keeping the cavity available for host–guest

• complexation. In that way, it was possible to decorate CDVs with carbohydrates [32][33], with peptides [34], and also with DNA [35]. Moreover CDVs were also shown to form very dense membranes in combination with phospholipids and cholesterol [36]. Previous studies also showed promising results for PDT

A journey in bioinspired supramolecular chemistry: from molecular tweezers to small molecules that target myotonic dystrophy

• Steven C. Zimmerman

Beilstein J. Org. Chem. 2016, 12, 125–138, doi:10.3762/bjoc.12.14

• host–guest chemistry [33]. Perry Corbin, Steven Dell, and I were pleased to work with Frank Klärner and his group on linking a host analogous to 20 to silica and to study the solvent effects on host–guest complexation chemistry using our HPLC method [34]. Many of the molecular tweezers described above

Supramolecular polymer assembly in aqueous solution arising from cyclodextrin host–guest complexation

• Jie Wang,
• Zhiqiang Qiu,
• Yiming Wang,
• Li Li,
• Xuhong Guo,
• Duc-Truc Pham,
• Stephen F. Lincoln and
• Robert K. Prud’homme

Beilstein J. Org. Chem. 2016, 12, 50–72, doi:10.3762/bjoc.12.7

• , Australia Department of Chemical Engineering, Princeton University, Princeton, NJ 08544, USA 10.3762/bjoc.12.7 Abstract The employment of cyclodextrin host–guest complexation to construct supramolecular assemblies with an emphasis on polymer networks is reviewed. The main driving force for this

• supramolecular assembly is host–guest complexation between cyclodextrin hosts and guest groups either of which may be discrete molecular species or substituents on a polymer backbone. The effects of such complexation on properties at the molecular and macroscopic levels are discussed. It is shown that

• with specific biofunctionality. Similar interactions may be utilized in the construction of functional materials. This is demonstrated in supramolecular assemblies based on cyclodextrin host–guest complexation which have attracted considerable interest through their applications in enzyme technology [5

The effect of permodified cyclodextrins encapsulation on the photophysical properties of a polyfluorene with randomly distributed electron-donor and rotaxane electron-acceptor units

• Aurica Farcas,
• Ana-Maria Resmerita,
• Pierre-Henri Aubert,
• Flavian Farcas,
• Iuliana Stoica and
• Anton Airinei

Beilstein J. Org. Chem. 2014, 10, 2145–2156, doi:10.3762/bjoc.10.222

• -CD, respectively. Changes in the absorption spectra of the monomer 1 upon the addition of increasing amounts of TMS-γ-CD in CHCl3. The inset shows the fitted binding constant curve based on a 1:1 host–guest complexation stoichiometry. 1H NMR spectrum of the polyrotaxane 4a copolymer in toluene-d8

• –guest complexation stoichiometry. Thus, the Ks in CHCl3 was determined to be approximately 205 and 150 (±30) M−1, respectively (see the determined Ks of 1b in Figure 2). Concerning the binding affinity of molecule 1 to the TMS-β-CD and TMS-γ-CD cavities, it should be mentioned that the values toward

• accurately due to the strong UV absorbance of this solvent. Thus, Ks measurements were performed in CHCl3. The Ks was determined by measuring the change in the absolute optical density (OD) at 314 nm with an increasing concentration of TMS-β-CD or TMS-γ-CD macrocycles and the fitting according to a 1:1 host

PEG-embedded KBr₃: A recyclable catalyst for multicomponent coupling reaction for the efficient synthesis of functionalized piperidines

• Sanny Verma,
• Suman L. Jain and
• Bir Sain

Beilstein J. Org. Chem. 2011, 7, 1334–1341, doi:10.3762/bjoc.7.157

• accessible catalytic protocol for the synthesis of functionalized piperidines by the one-pot coupling of aldehyde, amine and β-keto ester with PEG-wrapped KBr3 as a recyclable catalyst. The PEG-embedded tribromide could easily be synthesized through the concept of host–guest complexation [34] of PEGs with

Hyperbranched polyethylenimine bearing cyclodextrin moieties showing temperature and pH controlled dye release

• Indra Böhm,
• Susanne Katharina Kreth and
• Helmut Ritter

Beilstein J. Org. Chem. 2011, 7, 1130–1134, doi:10.3762/bjoc.7.130

• dye 1 could not be measured since the dye is not water-soluble and cannot be enclosed by CD. Complex 6 exhibits enlarged networks with a dH of 480 nm, which verifies an inclusion of both dyes (1 and 2) through salt formation and host-guest complexation (Supporting Information File 1, Figure S4). In