Complexation of molecular clips containing fragments of diphenylglycoluril and benzocrown ethers with paraquat and its derivatives

• Leonid S. Kikot',
• Catherine Yu. Kulygina,
• Alexander Yu. Lyapunov,
• Svetlana V. Shishkina,
• Roman I. Zubatyuk,
• Tatiana Yu. Bogaschenko and
• Tatiana I. Kirichenko

Beilstein J. Org. Chem. 2017, 13, 2056–2067, doi:10.3762/bjoc.13.203

• size and the nature of the substituents at the nitrogen atoms of the paraquat derivatives on the composition and stability of these complexes. Keywords: complexation; crown ethers; "host–guest chemistry"; molecular clips; paraquat; Introduction After the first report on the synthesis of crown ethers

• and their complexation properties made by Pedersen in 1967, "host–guest chemistry" attracted great attention [1]. In subsequent years, various types of crown compounds have been obtained, their complexation with metal ions, ammonium, and alkylammonium salts has been extensively studied. After Stoddart

• and co-workers in 1987 [2] reported the complexation of crown ethers with paraquat and diquat for the first time, these compounds have become the most commonly used models in the design of various systems such as host–guest and supramolecular assemblies based on crown ethers [3]. The development of

p-tert-Butylthiacalix[4]arenes functionalized by N-(4’-nitrophenyl)acetamide and N,N-diethylacetamide fragments: synthesis and binding of anionic guests

• Alena A. Vavilova and
• Ivan I. Stoikov

Beilstein J. Org. Chem. 2017, 13, 1940–1949, doi:10.3762/bjoc.13.188

• thiacalix[4]arenes 2, 7–10 (Figure 1) [26][42] with N-(4’-nitrophenyl)acetamide and N,N-diethylacetamide fragments was of interest. Initially, molecular modeling of the host–guest complexes of the above-mentioned thiacalix[4]arenes 2, 3, 5–10 with a number of single-charged anions (F−, Cl−, Br−, I−, CH3CO2

• correlates with an increase in the energy change in the formation of the host–guest complexes in the case of the macrocycles 3, 7. For the compounds 2, 6, 9, the efficiency of complexation is close. Conclusion New mono-, 1,2-di- and tetrasubstituted at the lower rim p-tert-butylthiacalix[4]arenes containing

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

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

• with the (S)-enantiomer [14]. Induced host–guest fit, made possible by the macrocyclic flexibility of the permethylated CDs plays a crucial role in their capacity for chiral discrimination. Chiral recognition of amino acids and their derivatives by CDs has been also tested using phase-solubility

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

• concentration of connector 9 necessary for the almost complete precipitation of the host polymer 8 can be explained by the high integrability of the host–guest system based on the shape-persistence of the polyconjugated polymer backbone of 8. Attachment of polymer 8 to silicon surfaces Planar silicon wafers, as

Inclusion complexes of β-cyclodextrin with tricyclic drugs: an X-ray diffraction, NMR and molecular dynamics study

• Franca Castiglione,
• Fabio Ganazzoli,
• Luciana Malpezzi,
• Andrea Mele,
• Walter Panzeri and
• Giuseppina Raffaini

Beilstein J. Org. Chem. 2017, 13, 714–719, doi:10.3762/bjoc.13.70

• , consistent with the 1:1 host–guest stoichiometry. Some important structural features of the inclusion complexes of 1 and 2 can be outlined by the analysis of the 1H NMR spectra: the spectrum of 1 shows that the AB quartet assigned to H9–H10 spin system is split into two AB quartets on passing from pure 1 to

• and refined with a riding model. Both complexes were found to crystallize in the solid state in 1:1 host–guest ratio with many partially disordered water molecules distributed in the intermolecular space outside the macrocyclic cavities. Full molecular and crystal data, together with the structural

• ]*Δδ vs r where r = [host]/[host]+[guest] (or related expression in the case the guest’s chemical shift variations are reported), providing the Job’s plot with the typical bell shape. The abscissa of the maximum provides the stoichiometry of the host–guest complex in solution. 2D NOE correlation

Fluorescent carbon dots from mono- and polysaccharides: synthesis, properties and applications

• Stephen Hill and
• M. Carmen Galan

Beilstein J. Org. Chem. 2017, 13, 675–693, doi:10.3762/bjoc.13.67

• ) when compared to 36% release at pH 7 and 27% at pH 12. In order to improve the drug delivery profile of the complex, the authors developed a β-cyclodextrin/tetracycline (β-TC) host–guest inclusion complex, which allows a second “barrier” of release. The pre-formulated β-TC complex was loaded onto the

Novel β-cyclodextrin–eosin conjugates

• Gábor Benkovics,
• Damien Afonso,
• András Darcsi,
• Szabolcs Béni,
• Sabrina Conoci,
• Éva Fenyvesi,
• Lajos Szente,
• Milo Malanga and
• Salvatore Sortino

Beilstein J. Org. Chem. 2017, 13, 543–551, doi:10.3762/bjoc.13.52

• aqueous medium, which precludes any response to light excitation. Keywords: β-cyclodextrins; fluorescence; photodynamic therapy; photosensitizers; singlet oxygen; xanthene; Introduction Cyclodextrins (CDs) are cyclic oligosaccharides able to form host–guest inclusion complexes with drugs and this

Structure–efficiency relationships of cyclodextrin scavengers in the hydrolytic degradation of organophosphorus compounds

• Sophie Letort,
• Michaël Bosco,
• Benedetta Cornelio,
• Frédérique Brégier,
• Sébastien Daulon,
• Géraldine Gouhier and
• François Estour

Beilstein J. Org. Chem. 2017, 13, 417–427, doi:10.3762/bjoc.13.45

• hydrolyze the organophosphorus (OP) compounds under physiological conditions. In this context, cyclodextrins (CD) constitute attractive starting materials because, due to the inclusion properties of their internal cavity, they can form host–guest complexes in aqueous media by weak interactions with small

Spectral and DFT studies of anion bound organic receptors: Time dependent studies and logic gate applications

• Srikala Pangannaya,
• Neethu Padinchare Purayil,
• Shweta Dabhi,
• Venu Mankad,
• Prafulla K. Jha,
• Satyam Shinde and
• Darshak R. Trivedi

Beilstein J. Org. Chem. 2017, 13, 222–238, doi:10.3762/bjoc.13.25

• oxygen atom. The enhancement of the ICT transition could be ascribed to a push–pull nature between the electron withdrawing –CN substituent and the conjugated system [39]. The appearance of a clear isosbestic point at 443 nm indicates the existence of a host–guest complex in the system. On the other hand

• efficient push–pull tendency existing in the host–guest interaction mechanism. The appearance of a clear isosbestic point at 500 nm clearly indicates the formation of the new complex. The complete disappearance of the absorbance at 459 nm at higher concentrations of fluoride and acetate ions is suggestive

• from 0.96 Å to 1.47 Å and 1.55 Å reflects the host–guest interaction. Mulliken charge distribution calculations showed a change of the atomic charge on the oxygen atom of receptors R1 and R2 from less negative to more negative values which are indicative for an intramolecular charge transfer process

Interactions between photoacidic 3-hydroxynaphtho[1,2-b]quinolizinium and cucurbit[7]uril: Influence on acidity in the ground and excited state

• Jonas Becher,
• Daria V. Berdnikova,
• Darinka Dzubiel,
• Heiko Ihmels and
• Phil M. Pithan

Beilstein J. Org. Chem. 2017, 13, 203–212, doi:10.3762/bjoc.13.23

• ). Unfortunately, the binding constants could not be determined from the titration data at pH 7 due to the complexity of the system resulting from several equilibrium processes. Thus, at pH > 6 the deprotonation of ligand 2 starts that – together with the host–guest equilibria – makes the system too complex for

• derivatives may be modulated by supramolecular interactions. Considering the ability of this class of compounds to operate as DNA-binding ligands [56] or water-soluble chemosensors [57], we anticipate that the combination of these properties with the potential for modulation by host–guest assembly may widen

• restrictions of the molecular movement of the guest ligand provided by confinement of the latter inside the host cavity. Nevertheless, the titrations show that the binding process depends on the pH of the solution (Figure 7), indicating the interference of the prototropic equilibrium (see below) with the host

Dynamics and interactions of ibuprofen in cyclodextrin nanosponges by solid-state NMR spectroscopy

• Monica Ferro,
• Franca Castiglione,
• Nadia Pastori,
• Carlo Punta,
• Lucio Melone,
• Walter Panzeri,
• Barbara Rossi,
• Francesco Trotta and
• Andrea Mele

Beilstein J. Org. Chem. 2017, 13, 182–194, doi:10.3762/bjoc.13.21

• formation of a host–guest inclusion complex – does not occur, confirming the situation already described by HR-MAS NMR data for the same system in the gel state [9] and outlining a different scenario on passing from monomeric CD, capable to form well characterized inclusion complexes with IbuH [29][30][31

• host–guest systems. Experimental Materials and measurements The detailed procedures for the synthesis of CDNS and the preparation of the corresponding hydrogels containing IbuNa can be found and seen in [34]. In the following, we report the essential information on the synthesis and the experimental

Phosphated cyclodextrins as water-soluble chiral NMR solvating agents for cationic compounds

• Cira Mollings Puentes and
• Thomas J. Wenzel

Beilstein J. Org. Chem. 2017, 13, 43–53, doi:10.3762/bjoc.13.6

• cationic form were individually tested with six different P-CDs at cyclodextrin concentrations of 5, 10 and 20 mM. All substrates, except for 14, have aromatic rings in their structures. Previous studies [21][31][32] and observations made herein with the P-CDs indicate that host–guest complexes through

Stabilization of nanosized titanium dioxide by cyclodextrin polymers and its photocatalytic effect on the degradation of wastewater pollutants

• Tamás Zoltán Agócs,
• István Puskás,
• Erzsébet Varga,
• Mónika Molnár and
• Éva Fenyvesi

Beilstein J. Org. Chem. 2016, 12, 2873–2882, doi:10.3762/bjoc.12.286

• pollutant of emerging concern (EP), was protected by CMBCD-P against the photocatalytic degradation showing that inclusion complex formation can result in opposite effects depending on the structure of the host–guest complex. Keywords: carboxymethyl β-cyclodextrin polymer; colloid stability; ibuprofen

• occur depending on the conformation of the host–guest complex (if the light-sensitive part of the molecule is located within or outside of the cavity), on the complex association constant and on the concentration ratio of the guest to the CD. It was shown that the photodecomposition of MB was enhanced

Computational methods in drug discovery

• Sumudu P. Leelananda and
• Steffen Lindert

Beilstein J. Org. Chem. 2016, 12, 2694–2718, doi:10.3762/bjoc.12.267

Interactions between cyclodextrins and cellular components: Towards greener medical applications?

• Loïc Leclercq

Beilstein J. Org. Chem. 2016, 12, 2644–2662, doi:10.3762/bjoc.12.261

• Loic Leclercq Univ. Lille, CNRS, ENSCL, UMR 8181 – UCCS - Equipe CÏSCO, F-59000 Lille, France 10.3762/bjoc.12.261 Abstract In the field of host–guest chemistry, some of the most widely used hosts are probably cyclodextrins (CDs). As CDs are able to increase the water solubility of numerous drugs

• ; greener active ingredients; host–guest chemistry; lipids; Introduction Cyclodextrins (CDs) were discovered and identified over a century ago [1][2][3]. Between 1911 and 1935, Pringsheim and co-workers demonstrated the ability of CDs to form complexes with many organic molecules [4][5]. Since the 1970s

• great variety of modified CDs has been developed to improve the stability and the solubility of inclusion complexes [8][9][10]. Nowadays, CDs are widely applied in many fields [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] due to their host–guest properties, their origins

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

• cyclodextrin vesicle surface. The supramolecular immobilization was monitored by using fluorescence spectroscopy and microscopy and the photochemistry of the squaraine was investigated by using absorption spectroscopy. Keywords: cyclodextrin; host–guest chemistry; photodynamic therapy; self-assembly

• 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

• squaraines can also be immobilized onto CDVs. For this purpose, the squaraines are equipped with two adamantane functions that bind into the cavities of cyclodextrin on the surface of the CDVs (Figure 1). The resulting divalent host–guest interaction should lead to a higher binding affinity of the squaraine

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

• α-CD and AA in water, we obtained a powder precipitate of a complex between α-CD and AA, although the crystal structure of α-CD and AA was not solved. The formation of precipitate implied the formation of a host-guest complex between them. A mixture of CDs (α-CD, β-CD and γ-CD) and AAm did not

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

• ]. In terms of surface area, tuneable porosity and feasible host–guest interaction, MOFs have scored over other above mentioned porous materials [6]. But the less hydrolytic stability of metal-organic frameworks limits their real time application [7][8]. So the search for new materials having high

Cross-linked cyclodextrin-based material for treatment of metals and organic substances present in industrial discharge waters

• Élise Euvrard,
• Nadia Morin-Crini,
• Coline Druart,
• Justine Bugnet,
• Bernard Martel,
• Cesare Cosentino,
• Virginie Moutarlier and
• Grégorio Crini

Beilstein J. Org. Chem. 2016, 12, 1826–1838, doi:10.3762/bjoc.12.172

• properties leading to a host–guest relationship with organic substances [6][7][8][9]. These cyclic oligosaccharides are water soluble in their native form and are often modified to prepare novel insoluble CD-based materials. Two patents published by Martel et al. [10], and Trotta et al. [11] can be consulted

• that polyBTCA-CD is a versatile sorbent able to retain substances present at concentrations close to a few milligrams per liter (metals and other inorganic elements) but also at trace concentrations (µg·L−1 for organics). Although ion exchange on the one hand, and host–guest inclusion on the other hand

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

• career phase. Our next move was into polymers, where we started the conceptual journey we are still taking. The key question we asked is "we know what happens when you have one host–guest dyad, but what happens when you have 10, 50, 100 on a polymer?" On a straightforward level, we were able to

Supramolecular chemistry at the interface of biology, materials and medicine

• Eric V. Anslyn and
• Steven C. Zimmerman

Beilstein J. Org. Chem. 2016, 12, 1101–1102, doi:10.3762/bjoc.12.105

• Eric V. Anslyn Steven C. Zimmerman Department of Chemistry, University of Texas, Austin, TX 78712, United States Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States 10.3762/bjoc.12.105 Keywords: biomimetic chemistry; host–guest chemistry

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

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

• was that I had “discovered” molecular concavity and host–guest chemistry, research that I instantly related to the action of the Cytochrome P-450s and other enzymes. Unfortunately however, there was the small problem of financial support. From John’s perspective I had literally appeared out of the

• direct assemblies, the structural definition and kinetic stability of 2:1 host–guest complexes might be low. We therefore wanted to introduce a bias by using very rigid guests. We were therefore grateful to discover that a range of steroids, from as small as estradiol to as large as cholesterol formed

• its exterior and a dry, water-free nano-space for harboring a guest or guests. The range of guests that form 2:1(2) host–guest complexes is illustrated by the examples in Figure 7. As expected, if a co-solvent is added then these complexes are broken down. Thus, screening of eight different co

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

• mentioning that among different kinds of non-covalent interactions, the host–guest type is extensively discussed in literature covering a large field of applications [4]. For example, cyclodextrins (CDs), among host molecules, are reported to occupy an important place in the field of inclusion phenomena [5

• absorbance difference measured at 337 nm in presence and in absence of CDs are summarized. As explained in [31], this change of absorption can be attributed to host–guest type interactions, during which the guest changes its environment from an aqueous medium to the apolar CD cavity inducing the variations

• well-established with the redox center of S4TdR located inside the host cavity. The results also indicated, as reported in [38], that S4TdR was reduced with more difficulty when it was engaged in the inclusion complexes. Sabapathy et al. [36] and Semeraro et al. [39] suggested that when host–guest type