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

• and the host–guest interactions must be able to equilibrate the previously described ortho–ortho' hindrance and to bring the aromatic rings of the caps to coplanar conformations. In this work, we decided to investigate a new cryptand in which this steric hindrance is removed. Thus, we changed the

• δ 8.49 ppm, marked with a black circle in Figure 2) of cryptand 2 upon titration with 1,5-dihydroxynaphthalene at different host:guest ratios are shown in Figure 3. Next the host–guest interactions were investigated by global non-linear regression analysis using the free tool that is available at

Crystal structure of the inclusion complex of cholesterol in β-cyclodextrin and molecular dynamics studies

• Elias Christoforides,
• Andreas Papaioannou and
• Kostas Bethanis

Beilstein J. Org. Chem. 2018, 14, 838–848, doi:10.3762/bjoc.14.69

• coordinates was based on the asymmetric unit of the determined structure and the dynamic behavior of the inclusion complex was monitored at two different temperatures (300 and 340 K) to gain some insight on the evolution of the host–guest interactions and to estimate the host–guest binding affinity in aqueous

• numerous van der Waals and C–H···O interactions mainly between the guest and the inner dimeric host cavity. The observed host–guest interactions along with the extended hydrogen bond network between water molecules, hosts and guest are listed analytically in Supporting Information File 1, Table S1. In

• stoichiometry 2:1) (Figure 2a) were subjected to equilibration and subsequent molecular dynamics simulations at both 300 and 340 K in explicit water solvent for almost 12 ns with the aim to monitor the dynamic behavior of CHL in β-CD in two different temperatures, study the host–guest interactions during the

Binding abilities of a chiral calix[4]resorcinarene: a polarimetric investigation on a complex case of study

• Marco Russo and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2017, 13, 2698–2709, doi:10.3762/bjoc.13.268

• the viewpoint of the methodologies for investigating host–guest binding equilibria. In fact, simple polarimetry has been recently demonstrated to be an appealing and versatile tool for studying the host–guest interactions that imply cyclodextrins (CDs) [41][42][43][44][45], as well as for a reliable

• considered separately. This suggests that the conformational and dynamic restrictions consequent to inclusion may be due to the occurrence of specific host–guest interactions rather than to a mere steric effect. In order to clarify the latter point, we investigated the possible structure of the complexes

Structural diversity in the host–guest complexes of the antifolate pemetrexed with native cyclodextrins: gas phase, solution and solid state studies

• Magdalena Ceborska,
• Magdalena Zimnicka,
• Aneta Aniela Kowalska,
• Kajetan Dąbrowa and
• Barbara Repeć

Beilstein J. Org. Chem. 2017, 13, 2252–2263, doi:10.3762/bjoc.13.222

• /bjoc.13.222 Abstract The complexation of the antifolate pemetrexed (PTX) with native cyclodextrins was studied. This process, along with the findings gathered for the structurally related folic acid was treated as a model for exploiting host–guest interactions of this class of guest molecules in the

• equivalent – methyl α-D-glucopyranoside – was investigated for a deeper understanding of the type of host–guest interactions. Solid state studies of PTX/CDs were performed using FTIR–ATR and Raman spectroscopy techniques. Keywords: antifolate; cyclodextrin; hydrophobic interactions; inclusion complexes

• identification of guest–host interactions is possible [17][18]. Any changes in the band position as well as increasing or decreasing of its intensity indicate complex formation. In that sense Raman spectroscopy emerges as an important technique for studying host–guest interactions, in particular for verifying if

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

• , ΔH, TΔS and N data (Table 1) for the PAAβ-CDen/PAAADen and PAAβ-CDen/PAAADhn systems is consistent with their host–guest interactions being similar in nature. The 2D NOESY 1H NMR spectrum of a D2O solution of PAAβ-CDen and PAAADddn in which the β-CDen and ADddn substituents are equimolar shows cross

Molecular recognition of N-acetyltryptophan enantiomers by β-cyclodextrin

• Spyros D. Chatziefthimiou,
• Mario Inclán,
• Petros Giastas,
• Athanasios Papakyriakou,
• Konstantina Yannakopoulou and
• Irene M. Mavridis

Beilstein J. Org. Chem. 2017, 13, 1572–1582, doi:10.3762/bjoc.13.157

• crystallization, as a consequence of accumulation of many soft host–guest interactions and of the imposed crystallographic order, thus resulting in very dissimilar propensity of each enantiomer to produce crystals with β-CD. Keywords: β-cyclodextrin; enantiomeric discrimination; N-acetyltryptophan; NMR; X-ray

• the CD macrocycle’s dimensions. The host–guest interactions established in the cavity are of van der Waals type, whereas between parts of the guest extending out of the cavity and the host’s hydroxy groups are H-bonding interactions and/or of electrostatic nature. CDs have been studied and used for

• the L-NAcTrp Cα atom only to generate the D-NAcTrp guest molecule. 3D maps of the observed dipolar, through-space host–guest interactions depicted so as to (a) reflect ≈equally strong cross-peaks in each L- and D-NAcTrp enantiomer for intramolecular correlations, namely guest H9,9’ with guest H6 and

Interactions between shape-persistent macromolecules as probed by AFM

• Johanna Blass,
• Jessica Brunke,
• Franziska Emmerich,
• Cédric Przybylski,
• Vasil M. Garamus,
• Artem Feoktystov,
• Roland Bennewitz,
• Gerhard Wenz and
• Marcel Albrecht

Beilstein J. Org. Chem. 2017, 13, 938–951, doi:10.3762/bjoc.13.95

• polyconjugated polymers ranged from 6 to 16 nm, depending on the side groups and the method of determination [9][10][11]. Among many supramolecular interactions, such as hydrogen bonding, π–π-interactions or hydrophobic host–guest interactions [12][13][14][15][16], the interactions of cyclodextrins (CDs) with

• investigation of cooperativity of multiple host–guest interactions using AFM has been reported by several groups [40][41][42][43][44][45]. Huskens and co-workers measured the supramolecular interactions between a β-CD-modified planar surface and mono-, di- and trivalent adamantane guest molecules attached to an

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

• –guest interactions. Confocal fluorescence microscopy of giant unilamellar vesicles (GUVs) of amphiphilic cyclodextrins with AdSq on their outer surface. Top: Absorption spectra at different time points during irradiation of a CDV solution with AdSq immobilised on the vesicle surface. Bottom: DLS spectra

• min. Top: Emission spectra (ex: 630 nm) of AdSq immobilized at CDV. [CDV] = 0–100 µM; [AdSq] = 5 µM. Bottom: Langmuir regression of a fluorescence titration of CDV to AdSq. [AdSq] = 10 µM, [CDV] = 0–100 µM. It is assumed that only cyclodextrins on the outer surface of the CDV are available for host

Radical polymerization by a supramolecular catalyst: cyclodextrin with a RAFT reagent

• Kohei Koyanagi,
• Yoshinori Takashima,
• Takashi Nakamura,
• Hiroyasu Yamaguchi and
• Akira Harada

Beilstein J. Org. Chem. 2016, 12, 2495–2502, doi:10.3762/bjoc.12.244

• catalysts have received a great deal of attention because they improve the selectivity and efficiency of reactions. Catalysts with host molecules exhibit specific reaction properties and recognize substrates via host–guest interactions. Here, we examined radical polymerization reactions with a chain

Superstructures with cyclodextrins: chemistry and applications III

• Gerhard Wenz and
• Eric Monflier

Beilstein J. Org. Chem. 2016, 12, 937–938, doi:10.3762/bjoc.12.91

• the group of B. J. Ravoo using host–guest interactions between polyethyleneimine grafted with β-CD and a polyamidoamine dendrimer decorated with ferrocene. The formation of the superstructures was reversible by electrochemical oxidation of the ferrocene moieties [6]. Furthermore, significant progress

Interactions between 4-thiothymidine and water-soluble cyclodextrins: Evidence for supramolecular structures in aqueous solutions

• Vito Rizzi,
• Sergio Matera,
• Paola Semeraro,
• Paola Fini and
• Pinalysa Cosma

Beilstein J. Org. Chem. 2016, 12, 549–563, doi:10.3762/bjoc.12.54

• ) [9]. In fact, FTIR spectra of these mixtures showed the typical signals of CDs and S4TdR, as a simple superposition of host and guest molecules related bands. In conclusion, FTIR–ATR measurements better indicate the type of host-guest interactions between CDs and S4TdR, with clear differences between

Supramolecular structures based on regioisomers of cinnamyl-α-cyclodextrins – new media for capillary separation techniques

• Gabor Benkovics,
• Ondrej Hodek,
• Martina Havlikova,
• Zuzana Bosakova,
• Pavel Coufal,
• Milo Malanga,
• Eva Fenyvesi,
• Andras Darcsi,
• Szabolcs Beni and
• Jindrich Jindrich

Beilstein J. Org. Chem. 2016, 12, 97–109, doi:10.3762/bjoc.12.11

• held together by non-covalent interactions, such as electrostatic interactions, coordination bonds, hydrogen bonds, hydrophobic interactions and host–guest interactions [1]. Their formation is spontaneous and reversible by self-assembly of the monomer units. Because of this special non-covalent

• mainly on intermolecular host–guest interactions between the hydrophobic interior of the CD in one conjugate and between the apolar substituent of another conjugate. Earlier studies however pointed out that the size matching between the covalently attached guest part and the CD’s cavity is not the only

• from the intermolecular host–guest interactions, the systems were further investigated using a series of 1H NMR spectra recorded at different concentrations. The chemical shifts of 1H resonances of both regioisomers changed as a function of concentration, although those recorded in DMSO-d6 were

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

• and of the tether between the hydrophobic substituents and the polymer backbone can substantially affect the host–guest interactions as is illustrated by studies of β-CD dimers and adamantyl-substituted poly(acrylate)s (Figure 9) [76]. (A similar situation also prevails for covalently-linked β-CD

• stimuli-responsive materials collectively called “smart materials”. These include “self-healing materials” which after being disrupted can recover their former state through host–guest interactions. Some examples of these materials are now discussed. 5.1 Photo-responsive materials Among the better known

Size-controlled and redox-responsive supramolecular nanoparticles

• Raquel Mejia-Ariza,
• Gavin A. Kronig and
• Jurriaan Huskens

Beilstein J. Org. Chem. 2015, 11, 2388–2399, doi:10.3762/bjoc.11.260

• their use as drug delivery vehicles. Here, we aim to form supramolecular nanoparticles (SNPs) by combining advantages of the reversible assembly properties of SNPs using host–guest interactions and of a stimulus-responsive moiety. The SNPs are composed of a core of positively charged poly(ethylene imine

• core of the SNPs. Keywords: host–guest interactions; nanoparticles; self-assembly; stimulus-responsive; supramolecular chemistry; Introduction Self-assembly and molecular recognition are two core concepts underlying supramolecular chemistry. These offer convenient and versatile pathways to

• these SNPs using host–guest interactions between CD and Ad. Tseng et al. studied the formation of SNPs that are assembled solely by host–guest interactions [11][12]. Here, the core is composed of multivalent interactions between positively charged CD-grafted polymers and positively charged poly

Co-solvation effect on the binding mode of the α-mangostin/β-cyclodextrin inclusion complex

• Chompoonut Rungnim,
• Sarunya Phunpee,
• Manaschai Kunaseth,
• Supawadee Namuangruk,
• Kanin Rungsardthong,
• Thanyada Rungrotmongkol and
• Uracha Ruktanonchai

Beilstein J. Org. Chem. 2015, 11, 2306–2317, doi:10.3762/bjoc.11.251

• anion affinity and selectivity of a neutral anion receptor, bis(cyclopeptide) [17]. Molecular dynamics (MD) simulations can give important insights into the energetics of structural interactions. The hydrated structure of β-CD in aqueous solution [18] and those showing host–guest interactions between

Synthesis and surface grafting of a β-cyclodextrin dimer facilitating cooperative inclusion of 2,6-ANS

• Lars W. Städe,
• Thorbjørn T. Nielsen,
• Laurent Duroux,
• Reinhard Wimmer,
• Kyoko Shimizu and
• Kim L. Larsen

Beilstein J. Org. Chem. 2015, 11, 514–523, doi:10.3762/bjoc.11.58

• grafting onto azide-functionalized quartz surfaces. Host–guest interactions with the fluorescent guest molecule 2-anilinonaphthalene-6-sulfonic acid (2,6-ANS) were investigated by NMR and fluorescence spectroscopy. Further, we probe the complex formation of the surface-grafted β-CD dimer with 2,6-ANS by

• negligible. Inclusion complex with free β-CD dimer in solution Host–guest interactions with the fluorescent probe 2,6-ANS were evaluated for the β-CD dimer by steady-state fluorescence spectroscopy and compared to that of the parent β-CD and 2,6-ANS. In water, 2,6-ANS displays only weak fluorescence

Towards the sequence-specific multivalent molecular recognition of cyclodextrin oligomers

• Michael Kurlemann and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2014, 10, 2428–2440, doi:10.3762/bjoc.10.253

• toxins or viruses and for imaging and targeted drug delivery [3]. Hydrogels which are built up by multivalent host–guest interactions and vesicles of amphiphilic host molecules have been intensively studied for their ability to function as drug delivery systems as well [4][5][6][7][8][9]. Additionally

• biofunctional materials [21][22][23][24][25][26][27]. Even the molecular recognition of macroscopic gel blocks by multivalent host–guest interactions has been realized [28][29][30][31][32]. Besides the number of receptor–ligand interactions their spatial distribution is crucial for the highly selective

• systems. Instead of calculating the EM it was estimated to be 0.25 mM because of the structural similarities of the system 2/9 with the systems 1/8 and 3/8. With a view to the much higher binding constant of 17 towards β-CD compared to all other possible host–guest interactions, it is obvious that this

Why a diaminopyrrolic tripodal receptor binds mannosides in acetonitrile but not in water?

• Diogo Vila-Viçosa,
• Oscar Francesconi and
• Miguel Machuqueiro

Beilstein J. Org. Chem. 2014, 10, 1513–1523, doi:10.3762/bjoc.10.156

• in water [14]. In fact, this receptor family [11][12][13] could only be tested in water at slightly acidic conditions, due to solubility reasons, and proved to be very inefficient [14]. Unraveling the molecular details of these host–guest interactions is crucial to understand their different

Homochiral BINOL-based macrocycles with π-electron-rich, electron-withdrawing or extended spacing units as receptors for C₆₀

• Marco Caricato,
• Silvia Díez González,
• Idoia Arandia Ariño and
• Dario Pasini

Beilstein J. Org. Chem. 2014, 10, 1308–1316, doi:10.3762/bjoc.10.132

• complexes in solution give insights into the role of nonspecific host–guest interactions (such as π–π stacking) for the overall stabilization of the complexes. We are currently designing binaphthyl-based hosts for the enantioselective recognition and separation of higher fullerenes and chiral nanotubes

End-group-functionalized poly(N,N-diethylacrylamide) via free-radical chain transfer polymerization: Influence of sulfur oxidation and cyclodextrin on self-organization and cloud points in water

• Sebastian Reinelt,
• Daniel Steinke and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 680–691, doi:10.3762/bjoc.10.61

• ]. Some publications make use of free-radical chain transfer polymerization and subsequent polymer post-modification [25][27][35][36]. The scope of our investigation was the preparation of multiple-stimuli-responsive PDEAAm polymers possessing hydrophobic end-groups suitable for host–guest interactions

• an increase of the cloud points of 8a–d up to values between 24.5 °C (8b) and 27.9 °C (8a) (Table 2). Due to the fact that the host–guest interactions are equilibria and the sterical accessibility of the polymer bound end-group is difficult, a slight excess of RAMEB-CD is necessary for the complete

Synthesis of enantiopure sugar-decorated six-armed triptycene derivatives

• Paola Bonaccorsi,
• Maria Luisa Di Gioia,
• Antonella Leggio,
• Lucio Minuti,
• Teresa Papalia,
• Carlo Siciliano,
• Andrea Temperini and
• Anna Barattucci

Beilstein J. Org. Chem. 2013, 9, 2410–2416, doi:10.3762/bjoc.9.278

• applications not only as glycoconjugates in glycochemistry, but also as interesting candidates for host–guest interactions by presenting a rigid lipophilic core surrounded by hydrophilic sugar moieties assembled on a rotor skeleton. The six-armed sugar-decorated triptycene derivatives might constitute a new

Structure elucidation of β-cyclodextrin–xylazine complex by a combination of quantitative ¹H–¹H ROESY and molecular dynamics studies

• Syed Mashhood Ali,
• Kehkeshan Fatma and
• Snehal Dhokale

Beilstein J. Org. Chem. 2013, 9, 1917–1924, doi:10.3762/bjoc.9.226

• . 1H–1H ROESY studies ROESY is an important tool for the study of large molecules and provides information on the through-space proximity of protons [19]. The host–guest interactions are displayed as intermolecular peaks between cavity protons and part of the guest involved in complexation. The

Linkage of α-cyclodextrin-terminated poly(dimethylsiloxanes) by inclusion of quasi bifunctional ferrocene

• Helmut Ritter,
• Berit Knudsen and
• Valerij Durnev

Beilstein J. Org. Chem. 2013, 9, 1278–1284, doi:10.3762/bjoc.9.144

• interactions of the siloxane derivatives with ferrocene Linking of the obtained polydimethyl and disiloxane derivatives through host–guest interactions with single ferrocene molecules generates supramolecular, connected siloxane chains. The guest molecule ferrocene was therefore dissolved in chloroform and

• strands can be linked with each other through the host–guest interactions of the terminal α-CD units and pure ferrocene without the need for covalent bonds. In order to complete the characterization of these host–guest interactions of the novel compounds, they were also examined by 2D ROESY NMR

• chloroform as solvent, by host–guest interactions of terminally attached α-CD with ferrocene as a quasi-bifunctional single guest molecule. The formation of noncovalent linkages was proved by the use of NMR spectroscopy and TEM images. However, it turned out that the stability of linking functions is

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

• was still inferior to unity (0.69), which indicated that the host–guest interactions were partially compensated by reduced solvation and loss of freedom of the host–guest system. One way to further improve the hydrophobic binding potential of a host in water is to add a salt such as NaCl [42]. From

Superstructures of fluorescent cyclodextrin via click-reaction

• Arkadius Maciollek,
• Helmut Ritter and
• Rainer Beckert

Beilstein J. Org. Chem. 2013, 9, 827–831, doi:10.3762/bjoc.9.94

• shape, through poly(host–guest)-interactions, was found. Furthermore, we were able to show the collapse of the supramolecular polymers upon addition of potassium adamantane-1-carboxylate. Experimental General remarks All reagents used were commercially available (Sigma-Aldrich, Acros Organics) and used

• , Humboldtstr. 10, 07743 Jena, Germany 10.3762/bjoc.9.94 Abstract Mono-(6-azido-6-deoxy)-β-cyclodextrin (CD) was covalently attached to an alkyne-modified 5-methyl-2-(pyridin-2-yl)thiazol-4-ol yielding a fluorophore containing CD in a click-type reaction. Intermolecular complexes were formed by poly(host–guest

• )-interactions. The supramolecular structures were characterized by 1H NMR-ROESY spectroscopy, dynamic light scattering, UV–vis spectroscopy, fluorescence spectroscopy, and asymmetric flow field-flow fractionation. By adding potassium adamantane-1-carboxylate, the thiazol dye is displaced from the CD-cavity and