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

• tryptophan and Trp-containing peptides by 1 we performed NMR measurements on the 1:1 host–guest complexes in D2O. Upon binding of tryptophan by 1 a significant upfield shift of the aromatic protons and a slightly smaller shift, also upfield, of the α and β-Trp protons was observed (Figure 3). The aromatic

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

• can abduct it from the terpyridine. The luminescence properties in the closed state can also be modulated by the formation of host–guest complexes. This happens with ligands complexing the metal center only, such as terpyridines and phenanthrolines. In fact, the counterions of the zinc2+ cation and

• the reduced basicity of the second pyrimidine’s nitrogen when the first is already coordinated. The py-pym-py closed-by-default “U”-shaped systems form host–guest complexes with electron-poor guests such as TNF. These tweezers are thus a three-state system controlled by copper(I) with allosterically

• with electronically differentiated states using the tweezers' switching and modulation of host–guest complexes' electronic properties [69][70]. Sessler also explored the host–guest properties of the cone conformation towards the complexation of fullerenes. Indeed, the large cavity of the cone

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

• [23][24][25][26] and CH–π interactions [27][28][29][30], forming the corresponding host–guest complexes. In addition, the concave outer surface of the CPP also interacts with the convex surface of the CPP (Figure 1b) [31][32][33], resulting in the formation of the shortest possible double-layer CNTs

• up new possibilities for the fabrication of supramolecular structures based on the non-covalent interactions using carbon nanorings [37][38]. Despite the unique structure of the host–guest complexes, however, their electronic structures are not very attractive. This is because the complex formation

• will help tune the electronic properties of the host–guest complexes and design novel materials based on hierarchical supramolecular structures involving cyclic nanocarbons. Structures of a) [10]CPP⊃C60, (b) [n+5]CPP⊃[n]CPP, and (c) [10]CPP⊃[5]CPP2+ (this work). 1H NMR spectra (CD2Cl2, 25 °C) of a) a

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

• modelling and solid-state X-ray analysis, provides a detailed description of the spatial arrangement of cyclodextrin host–guest complexes in solution. The chiral cavity of the cyclodextrin molecule creates an anisotropic environment for the guest molecule resulting in a splitting of its prochiral carbon

• crystallization of host–guest complexes and their crystallographic analysis. Keywords: anisotropy; 13C NMR; cyclodextrin; host–guest complexes; Introduction Complexation of organic and inorganic compounds with α-, β-, or γ-cyclodextrins and their derivatives [1] is an established tool used in medicine for drug

• calorimetry [13]. Single crystals for many host–guest complexes have been prepared, and their structure elucidated by X-ray crystallography [14][15]. Conformations of host–guest complexes in solution have been studied by 2D NMR experiments [11] (NOESY, ROESY) or proposed computationally [16][17] based on

Tying a knot between crown ethers and porphyrins

• Maksym Matviyishyn and
• Bartosz Szyszko

Beilstein J. Org. Chem. 2023, 19, 1630–1650, doi:10.3762/bjoc.19.120

• sodium(I), zinc(II), magnesium(II), and barium(II) [106][107][108][109]. Association constants of the reported host–guest complexes showed similar values to those of diazacrown ethers [110][111]. Johnston and Gunter presented a crown ether-capped porphyrin receptor 10, which showed unexpected binding

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

• , partial least square (PLS) modeling was used for the determination of the composition of solutions containing tryptophan methyl ester, phenylalanine, norephedrine, N,N’-bis-(α-methylbenzyl)sulfamide, sulfaguanidine or sulfamethoxazole using the spectral data of the corresponding CD host–guest complexes

1,4,6,10-Tetraazaadamantanes (TAADs) with N-amino groups: synthesis and formation of boron chelates and host–guest complexes

• Artem N. Semakin,
• Ivan S. Golovanov,
• Yulia V. Nelyubina and
• Alexey Yu. Sukhorukov

Beilstein J. Org. Chem. 2022, 18, 1424–1434, doi:10.3762/bjoc.18.148

• hydrazone groups. The use of N-TAAD derivatives as potential ligands and receptors was showcased through forming boron chelates and host–guest complexes with water and simple alcohols. Keywords: azaadamantanes; cyclotrimerization; hydrazones; inclusion complexes; molecular recognition; Introduction

• as synthetic receptors to form host–guest complexes based on H-bond interactions with amide/carbamoyl groups [31][32]. In addition, N-TAADs can be viewed as analogs of hexahydrazide ligands, which were reported to stabilize high-valent metal complexes [33][34]. Since N-amino groups can be easily

• of the obtained TAAD derivatives were performed, and the formation of boron chelates and host–guest complexes having an unusual intramolecular H-bonded network was showcased in this work. Results and Discussion Synthesis of 3N-TAADs, 2N,1O-TAADs and 1N,2O-TAADs Our strategy to construct TAAD

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

• (CXs), cyclodextrins (CDs), cucurbiturils (CBs), and pillararenes, are of particular interest because they can act as vehicles for anticancer drugs by either self-assembling into nanocarriers [14][15][16] or forming host–guest complexes with anticancer drugs [17][18][19][20]. Tribenzotriquinacene (TBTQ

• delivery [28]. These findings therefore opened up the possibility for supramolecular chemotherapy based on TBTQ derivatives. However, the use of TBTQ derivatives as hosts to directly encapsulate drugs by forming host–guest complexes has not been reported. In this paper, we report a new water-soluble

• derivative with an extended cavity that can associate with anticancer drugs through host–guest interactions. The resulting host–guest complexes can be considered as camouflaged anticancer drugs that may exhibit low or no cytotoxicity in normal cellular environment. Furthermore, it is hoped that the release

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

• complexes (1:1, 2:1, 1:2, and 2:2). For the 1:1, 2:1, and 1:2 host–guest complexes, the thermodynamic association (Ka) and dissociation constants (Kd) for the reactive guests and photoproducts are crucial for the fundamental understanding of supramolecular noncovalent interactions [12][13]. In addition

• comprehensive investigation of the kinetic and thermodynamic aspects relating to the host–guest interactions and photochemical transformation efficiency of the substrate [10][11]. Thus, this review highlights the supramolecular photocatalytic substrate transformation involving various stoichiometric host–guest

Using multiple self-sorting for switching functions in discrete multicomponent systems

• Amit Ghosh and
• Michael Schmittel

Beilstein J. Org. Chem. 2020, 16, 2831–2853, doi:10.3762/bjoc.16.233

• ), cucurbit[7]uril (3), and the two chalcones 1 and 2 in aqueous solution [48]. When the hosts 3 and 4 were mixed with the trans-chalcones 1 and 2 as guests in a 1:1:1:1 ratio, instantly a statistical mixture formed displaying all four possible host–guest complexes. After the exposure to an acid, the ensuing

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

• the host–guest complexes is primarily due to hydrophobic effects and π–π interactions. The TBTQ-(OG)6 C60 complex was found to further assemble to microspheres with diameters of 0.3–3.5 μm. The inclusion complexation between TBTQ-(OG)6 and fullerenes in aqueous solution may shed light on potential

• ), 1629.1 (24) %; HRESIMS (negative mode, m/z): [M – 2 H]2− calcd for C77H94N18O362−, 923.3045; found, 923.3014 (Δ = −3.3 ppm). Selected TBTQ derivatives 1–5 that bind fullerenes in host–guest complexes. Fluorescence spectra of TBTQ-(OG)6 (5.0 × 10−6 M) with varying concentrations of (a) C60 and (b) C70

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

• ][2][3]. As a consequence of the specific structural features of Q[n]s, which have two hydrophilic “portals” decorated with partially negatively charged carbonyl groups and a hydrophobic cavity [4], cucurbit[n]urils are able to form host–guest complexes with a range of drugs [5][6][7]. These complexes

A chiral self-sorting photoresponsive coordination cage based on overcrowded alkenes

• Constantin Stuckhardt,
• Diederik Roke,
• Wojciech Danowski,
• Edwin Otten,
• Sander J. Wezenberg and
• Ben L. Feringa

Beilstein J. Org. Chem. 2019, 15, 2767–2773, doi:10.3762/bjoc.15.268

• between the three isomers. Two of the isomers were able to form host–guest complexes opening up new prospects toward stimuli-controlled substrate binding and release. Keywords: coordination cages; molecular motors; molecular switches; overcrowded alkene; palladium; Introduction Supramolecular

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

• intermolecular hydrogen bonds of the dimer. Smaller quaternary cations Me4N+ and Et4N+ were observed to form 1:1 and 2:1 host–guest complexes. With Me4N+, [12 + Me4N]+ was observed in the positive mode, and ions [1 − 2H + Me4N]− and [12 − 2H + Me4N]− in the negative mode (Figure 1). Complexation of Et4N+ was

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

• ability of 3a to bind various anion species in gas phase. To our delight, host molecule 3a co-crystalized with n-Bu4NX (X = Cl, Br) from diffusion of diethyl ether vapor into ethyl acetate solution at ambient temperature to give single crystals of the host–guest complexes (n-Bu4NX)3-3a (X = Cl, Br). X-ray

• 3.136 Å (Cl−) or from 3.194 Å to 3.280 Å (Br−). The location of anion above the tetrazine centroid with the shorter distance than the sum of van der Waals radius indicated explicitly the typical noncovalent anion–π attraction. It is interesting to point out that in the host–guest complexes, all

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

• a hydrophobic effect, while the other one has a more directional character, or application of multidentate interaction sites [3]. Macrocyclic compounds with persistent hydrophobic cavities constitute a fundamental class of scaffolds for the construction of supramolecular host–guest complexes in

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

• face with primary hydroxy groups and a wider secondary face with secondary hydroxy groups [6][7]. With the hydrophobic cavity and the hydrophilic hydroxy groups, CDs efficiently form host–guest complexes with different hydrophobic guests in aqueous medium [8][9]. Among the common CDs, γ-CD possesses a

• 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

• efficiently obtained by using both CB[6] and γ-CD which are interlocked onto the axle by orthogonal interactions. Of note, the γ-CD in all the rotaxanes are only singly threaded, suggesting that further guest molecules could bind to the γ-CD cavity to give interesting host–guest complexes with the [n

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

• –S22). Furthermore, job plots showed that throughout 1:1 host–guest complexes are formed (Supporting Information File 1, Figures S56–S88). To gain quantitative insight into the complexation between the hosts and the guests, we carried out 1H NMR titrations and calculated the association constants Ka by

• different polarity can also affect the complexation between the hosts and the guests. As shown in Table 2, we found that performing the 1H NMR titrations of the host–guest complexation in CDCl3/acetone-d6 1:2 (v/v), the Ka values of the 1:1 host–guest complexes were about 103 M−1 except for H2 that showed

• -polar solvent, acetone hampers or competes the intermolecular non-covalent interactions between the hosts and the guests, and thus resulted in a decrease of the host–guest complexation. ESIMS studies of the formation of host–guest complexes The electrospray ionization (ESI) mass spectra also confirmed

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

• GC5A–dye complexes. Binding constants and photophysical properties of host–guest complexes and the calculated polarities of macrocyclic hosts. Acknowledgements This work was supported by NSFC (21672112 and 51873090), the Fundamental Research Funds for the Central Universities and Program of Tianjin

Fabrication, characterization and adsorption properties of cucurbit[7]uril-functionalized polycaprolactone electrospun nanofibrous membranes

• Changzhong Chen,
• Fengbo Liu,
• Xiongzhi Zhang,
• Zhiyong Zhao and
• Simin Liu

Beilstein J. Org. Chem. 2019, 15, 992–999, doi:10.3762/bjoc.15.97

• expected that CB[7] molecules in the nanofibers have free cavities, able to an effective capture of target molecules from the surroundings through the formation of host–guest complexes. As collected in Table S2 (Supporting Information File 1), the melting enthalpy and crystallization enthalpy of neat PCL

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

• supramolecular fiber materials composed of cyclodextrin (CD)–fullerene inclusion complexes by electrospinning. Similar to the molecular state of fullerenes in solution, the resulting fibers include molecularly-dispersed fullerenes. We believe such a concept could be expanded to diverse host–guest complexes

Enhanced single-isomer separation and pseudoenantiomer resolution of new primary rim heterobifunctionalized α-cyclodextrin derivatives

• Iveta Tichá,
• Gábor Benkovics,
• Milo Malanga and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2018, 14, 2829–2837, doi:10.3762/bjoc.14.261

• ; heterobifunctionalized alpha-cyclodextrin; homobifunctionalized alpha-cyclodextrin; regioisomers; regioselectivity; Introduction Cyclodextrins, cyclic cone-shaped oligosaccharides [1], have long attracted interest for their properties in host–guest complexes both in research and in pharmaceutical and food industry

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

• = (2.29 ± 0.27) × 106 M−1) is 3.9 times larger than that of P (Ka = (5.87 ± 0.24) × 105 M−1). Keywords: berberine; biphenarenes; host–guest complexes; molecular recognition; palmatine; Introduction Host–guest chemistry in water is significantly important due to its extensive applications in biology

Rational design of boron-dipyrromethene (BODIPY) reporter dyes for cucurbit[7]uril

• Mohammad A. Alnajjar,
• Jürgen Bartelmeß,
• Robert Hein,
• Pichandi Ashokkumar,
• Mohamed Nilam,
• Werner M. Nau,
• Knut Rurack and
• Andreas Hennig

Beilstein J. Org. Chem. 2018, 14, 1961–1971, doi:10.3762/bjoc.14.171

• pKa values from the direct titration and from the global fitting agreed reasonably well, and the complexation-induced pKa shifts were in the typical range reported for CB7 host–guest complexes [58]. Application of BODIPY-CB7 complexes The availability of BODIPY dyes, which respond towards complexation

• of fluorescent host–guest complexes, for example, indicator displacement assays with absorption and emission wavelengths in the visible spectral region, fluorescence correlation spectroscopy, and noncovalent surface functionalization with fluorophores. Furthermore, the strategy is similarly

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

• aggregation of the hydrophobic alkyl chain rings, which induced insolubilization of the bicyclic compound in aqueous media at 20 °C and a decrease in its clouding point. Keywords: amphiphilic molecules; host–guest complexes; lower critical solution temperature; pillar[n]arenes; pseudo[1]catenane

• inside to the outside of the cavity, a competitive guest molecule, 1,4-dicyanobutane, was added. 1,4-Dicyanobutane was chosen because it forms highly stable 1:1 host–guest complexes with pillar[5]arenes (K > 104 M−1) [20]. Figure 2d shows the 1H NMR spectra of 3 in the presence of 1,4-dicyanobutane. In

• the spectrum, additional peaks were observed upon the addition of 1,4-dicyanobutane (orange peaks α’ and β’) in Figure 2d. For comparison Figure 2e shows the spectrum of 1,4-dycanaobutane (orange peaks α and β). Similar signals were also observed in the host–guest complexes of 1,4-dicyanobutane with