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

• associative forces including hydrogen bonding, coordinate bonding, electrostatic interactions and hydrophobic interactions is ubiquitous in nature. This is exemplified by the use of DNA and RNA complementarity [1][2] and polypeptide helix formation [3][4] to produce three-dimensional structures and materials

• outline of the annulus is shown for uniformity and simplicity in this review.) Review 1 Host–guest complexation between cyclodextrins and guest-substituted polymers 1.1 Modulation of hydrophobic interactions Hydrophobic interactions of water soluble polymers substituted with either terminal hydrophobic

• almost a half and the viscosity profile is little changed (Figure 4a). This is consistent with n-C18H37 partially protruding from the narrow α-CD annulus such that residual hydrophobic interactions occur between n-C18H37 substituents and substantial viscosity is retained. However, when the α-CD:n-C18H37

Determination of formation constants and structural characterization of cyclodextrin inclusion complexes with two phenolic isomers: carvacrol and thymol

• Miriana Kfoury,
• David Landy,
• Steven Ruellan,
• Lizette Auezova,
• Hélène Greige-Gerges and
• Sophie Fourmentin

Beilstein J. Org. Chem. 2016, 12, 29–42, doi:10.3762/bjoc.12.5

• enhanced steric hindrance caused by the ortho position of the hydroxy group (Figure 1). Moreover, 1 presents a relatively superior hydrophobic character than 2, as expressed by logP values (Figure 1), which additionally reinforces hydrophobic interactions with the apolar CD cavity. Phase solubility studies

• hydrophobic interactions with the interior of the CD cavity [44][45]. Additionally, this revealed some conformational changes generated by the inclusion of 1 and 2 in the CD. The downfield shift observed for other guests’ protons is due to a variation in the polarity of their micro-environment when 1 and 2

Synthesis and photophysical characteristics of polyfluorene polyrotaxanes

• Aurica Farcas,
• Giulia Tregnago,
• Ana-Maria Resmerita,
• Pierre-Henri Aubert and
• Franco Cacialli

Beilstein J. Org. Chem. 2015, 11, 2677–2688, doi:10.3762/bjoc.11.288

• well as hydrophobic interactions. CD liphophilic derivatives are more soluble in non-polar solvents and water and exhibit lower propensity to aggregate than native CDs [40][41][42]. Considering that larger hydrophobic CD surfaces can lead to increased interactions with the hydrophobic aromatic guest

• synthesis of 1·TM-βCD or 1·TM-γCD in polar protic solvents is driven by hydrophobic interactions in combination with electrostatic, van der Waals or π–π interactions. In comparison, in polar aprotic solvents such as DMF, THF relies mostly on host–guest specific interactions, such as dispersion or dipole

• ) suggesting that about every three structural unit was threaded with TM-βCD macrocycle. However, compared with native CD [43][45], 1H NMR results suggest poor hydrophobic–hydrophobic interactions of molecule 1 towards TM-βCD. Unfortunately, as a consequence of the low Ks of 1·TM-γCD, the polyrotaxane 3·TM-γCD

Aggregation behaviour of amphiphilic cyclodextrins: the nucleation stage by atomistic molecular dynamics simulations

• Giuseppina Raffaini,
• Antonino Mazzaglia and
• Fabio Ganazzoli

Beilstein J. Org. Chem. 2015, 11, 2459–2473, doi:10.3762/bjoc.11.267

• ]. In this case, the aCD would show a relatively more hydrophobic nature than our model aCD. We can thus speculate that mutual inclusion of the polar chains in the cavity of neighbouring molecules as found in the present paper would be more unlikely because of the enhanced hydrophobic interactions among

Active site diversification of P450cam with indole generates catalysts for benzylic oxidation reactions

• Paul P. Kelly,
• Anja Eichler,
• Susanne Herter,
• David C. Kranz,
• Nicholas J. Turner and
• Sabine L. Flitsch

Beilstein J. Org. Chem. 2015, 11, 1713–1720, doi:10.3762/bjoc.11.186

• earlier specified by Loida and Sligar [21], which have been recently identified as universal selectivity determining positions within the P450 enzyme family [22]. In addition, Phe98 and Met184 mutant libraries were generated since Phe98 is thought to contribute to substrate orientation via hydrophobic

• interactions [23], whereas Met184 is part of the P450cam substrate recognition site 2 (SRS 2) [24]. Accordingly, the entire P450cam active site was partitioned into seven residue pairs which were targeted in site-directed mutagenesis experiments in the manner of CASTing (Figure 1) [25]. NDT codon degeneracy

Mechanical stability of bivalent transition metal complexes analyzed by single-molecule force spectroscopy

• Manuel Gensler,
• Christian Eidamshaus,
• Maurice Taszarek,
• Hans-Ulrich Reissig and
• Jürgen P. Rabe

Beilstein J. Org. Chem. 2015, 11, 817–827, doi:10.3762/bjoc.11.91

• and possible hydrophobic interactions was published in 2009 by Zhang et al. [37]. They compared the monovalent interaction of a porphyrin ligand to a C60 fullerene with the bivalent interaction of two ligands to one C60 (pincer complex) in aqueous environment. Thereby the rupture length decreased from

Conjugates of methylated cyclodextrin derivatives and hydroxyethyl starch (HES): Synthesis, cytotoxicity and inclusion of anaesthetic actives

• Lisa Markenstein,
• Antje Appelt-Menzel,
• Marco Metzger and
• Gerhard Wenz

Beilstein J. Org. Chem. 2014, 10, 3087–3096, doi:10.3762/bjoc.10.325

• conjugates, listed in Table 1, were clearly soluble in water at ambient conditions but most of them precipitated at elevated temperatures. This so-called lower critical solution temperature is typical for alkylated neutral polysaccharides and attributed to increasing hydrophobic interactions with increasing

Synthesis of an organic-soluble π-conjugated [3]rotaxane via rotation of glucopyranose units in permethylated β-cyclodextrin

• Jun Terao,
• Yohei Konoshima,
• Akitoshi Matono,
• Hiroshi Masai,
• Tetsuaki Fujihara and
• Yasushi Tsuji

Beilstein J. Org. Chem. 2014, 10, 2800–2808, doi:10.3762/bjoc.10.297

• luminescent properties [3][4][5]. Cyclodextrin (CD) derivatives are widely used as a protective sheath for the synthesis of IMWs because they are easily obtainable and efficient in the inclusion of various polymers into their cavity via hydrophobic interactions in water [6][7]. General methods for the

• permethylation of all the hydroxy groups of CD. However, the low solubility of PMCD in water as compared with native CDs or other randomly methylated CDs such as 2,6-dimethyl-β-cyclodextrin impedes the formation of self-inclusion complexes via hydrophobic interactions in water. To rise above this problem, we

Linear-g-hyperbranched and cyclodextrin-based amphiphilic block copolymer as a multifunctional nanocarrier

• Yamei Zhao,
• Wei Tian,
• Guang Yang and
• Xiaodong Fan

Beilstein J. Org. Chem. 2014, 10, 2696–2703, doi:10.3762/bjoc.10.284

• , their cumulative release amounts were 11.6, 9.5, and 6.8%, respectively, within 14 h. This may be attributed to the introduction of the HBPCSi segments and β-CD moieties. Generally, the hydrophobic–hydrophobic interactions between drug molecules and hydrophobic core layer of micelles make an important

• contribution to the sustained release of drugs from micelles [32][34]. In our micelle systems, the hydrophobicity of the core layer of MP2 was enhanced with the introduction of the HBPCSi segments, followed by the enhancement of hydrophobic–hydrophobic interactions between LND molecules and the core layer. As

Gold(I)-catalysed synthesis of a furan analogue of thiamine pyrophosphate

• Amjid Iqbal,
• El-Habib Sahraoui and
• Finian J. Leeper

Beilstein J. Org. Chem. 2014, 10, 2580–2585, doi:10.3762/bjoc.10.270

• ThDP, with increased hydrophobic interactions between the enzyme and the electrically neutral analogue compared to the positively charged ThDP [11]. The synthesis of 2 was achieved in 12 steps in reasonable yield but was lengthy and time-consuming. For this reason other analogues have also been studied

Effect of cyclodextrin complexation on phenylpropanoids’ solubility and antioxidant activity

• Miriana Kfoury,
• David Landy,
• Lizette Auezova,
• Hélène Greige-Gerges and
• Sophie Fourmentin

Beilstein J. Org. Chem. 2014, 10, 2322–2331, doi:10.3762/bjoc.10.241

• either in solution or in solid state [14]. The relative stabilities of inclusion complexes are governed by different factors such as hydrogen bonding, hydrophobic interactions, solvation effects as well as the guest molecule's space filling ability [15][16]. CD derivatives are also of great importance

• of hydrophobic interactions and are in good agreement with literature data [21][28][29][30][41]. Determination of DPPH radical scavenging activity The DPPH• assay was used to measure the radical scavenging activity of PPs. Depending on the studied PP, two types of kinetic behavior were observed

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

• coverage ratio of ca. 37.6% was obtained for 4b polyrotaxane, see Figure S5 in Supporting Information File 1. It should be pointed out that the lower coverage compared to native γ-CD [13] can be assigned to the poor hydrophobic–hydrophobic interactions of molecule 1 towards TMS-β-CD and TMS-γ-CD. The

Expeditive synthesis of trithiotriazine-cored glycoclusters and inhibition of Pseudomonas aeruginosa biofilm formation

• Meriem Smadhi,
• Sophie de Bentzmann,
• Anne Imberty,
• Marc Gingras,
• Raoudha Abderrahim and
• Peter G. Goekjian

Beilstein J. Org. Chem. 2014, 10, 1981–1990, doi:10.3762/bjoc.10.206

• show a relatively less unfavorable entropy contribution, compared to methyl β-D-galactopyranoside, which is consistent with the contribution of additional hydrophobic interactions. No chelate binding is expected in this first generation cluster, as the arm length is well below the 29 Å distance between

Synthesis and solvodynamic diameter measurements of closely related mannodendrimers for the study of multivalent carbohydrate–protein interactions

• Yoann M. Chabre,
• Alex Papadopoulos,
• Alexandre A. Arnold and
• René Roy

Beilstein J. Org. Chem. 2014, 10, 1524–1535, doi:10.3762/bjoc.10.157

• moieties and an aromatic central core but the introduction of distinct functionalized linkers may change the overall hydrophobic/hydrophilic balances of the structures. As such, they could engage supplementary intramolecular hydrogen bonding or hydrophobic interactions that could mediate their three

Automated solid-phase peptide synthesis to obtain therapeutic peptides

• Veronika Mäde,
• Sylvia Els-Heindl and
• Annette G. Beck-Sickinger

Beilstein J. Org. Chem. 2014, 10, 1197–1212, doi:10.3762/bjoc.10.118

• drugs in the blood. Early structural studies described a spherical folding of albumin [92] allowing electrostatic interaction between the carboxylate anion of fatty acids and positively charged residues of albumin [93]. Furthermore, hydrophobic interactions were shown to contribute to albumin binding in

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

• remarkable effect on the cloud point of the polymers bearing a 4-tert-octylphenol end-group compared to the 4-tert-butylphenol end-group could be expected. Consequently hydrophobic interactions must play an important role for this effect. Regarding Figure 4 and Table 2 the hydrophobic interactions seem to be

Diastereoselectivity in the Staudinger reaction of pentafluorosulfanylaldimines and ketimines

• Alexander Penger,
• Cortney N. von Hahmann,
• Alexander S. Filatov and
• John T. Welch

Beilstein J. Org. Chem. 2013, 9, 2675–2680, doi:10.3762/bjoc.9.303

• minimization of unfavourable hydrophobic interactions. Results and Discussion The use of fluoroalkylimines to form β-lactams has proven especially useful in synthesis [24][25][26] especially in the Ojima β-lactam synthon method [27][28][29] used to prepare docetaxel analogs [26]. The general utility of the

Synthesis of enantiomerically pure (2S,3S)-5,5,5-trifluoroisoleucine and (2R,3S)-5,5,5-trifluoro-allo-isoleucine

• Holger Erdbrink,
• Elisabeth K. Nyakatura,
• Susanne Huhmann,
• Ulla I. M. Gerling,
• Dieter Lentz,
• Beate Koksch and
• Constantin Czekelius

Beilstein J. Org. Chem. 2013, 9, 2009–2014, doi:10.3762/bjoc.9.236

• biological membrane or the kind of hydrophobic interactions, that would be present in hydrophobic cores of proteins and in ligand–receptor binding [27]. We extended these initial studies by 2-aminoheptanoic acid (Aha) as an amino acid with an unbranched aliphatic side chain. The van der Waals volumes of the

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

• mol−1 for p-tert-butylbenzoate [3]. The observed increase of complex stability with increasing size of the hydrophobic part of the guest can be explained by the increase of hydrophobic interactions as well as other nonpolar interactions, e.g., van der Waals and dispersive interactions [9]. The

• molecular origin of hydrophobic interactions in general was already discussed controversially for many years [10][11][12][13]. Reliable quantitative predictive models are still missing [14]. Expulsion of “high energy water” from a cavity during space filling by a hydrophobic guest appears to be the main

• complexing abilities in terms of space filling of the cavities. Our systems are well-defined models for reaching a better understanding of hydrophobic interactions in general and are useful for the calibration of predictive tools. Results and Discussion A series of commercially available monosubstituted

Molecular solubilization of fullerene C₆₀ in water by γ-cyclodextrin thioethers

• Hai Ming Wang and
• Gerhard Wenz

Beilstein J. Org. Chem. 2012, 8, 1644–1651, doi:10.3762/bjoc.8.188

• ][25]. CDs form water-soluble inclusion complexes with many hydrophobic or amphiphilic guest molecules [26], mainly driven by hydrophobic interactions [27]. Among the commercially available CDs, γ-CD with a clear width of d = 0.74 nm [28] is only large enough to partially accommodate C60, which has a

High-affinity multivalent wheat germ agglutinin ligands by one-pot click reaction

• Henning S. G. Beckmann,
• Heiko M. Möller and
• Valentin Wittmann

Beilstein J. Org. Chem. 2012, 8, 819–826, doi:10.3762/bjoc.8.91

• ’-diacetylchitobiose is a much better inhibitor than GlcNAc, which is in accordance with the association constants determined by solution binding assays [47]. The benzyl triazolyl appendage of C1 further enhances binding by a factor of two, probably due to additional weak hydrophobic interactions. However, introducing

Investigation of the network of preferred interactions in an artificial coiled-coil association using the peptide array technique

• Raheleh Rezaei Araghi,
• Carsten C. Mahrenholz,
• Rudolf Volkmer and
• Beate Koksch

Beilstein J. Org. Chem. 2012, 8, 640–649, doi:10.3762/bjoc.8.71

• hydrophobic interactions between the αβγ-peptide and its natural α-partner. Similarly, the interactions between the peptides on the array and the chimera decrease drastically in sequences presenting the shorter side chains of Val and Ala at a and d positions, compared to mutants with the longer and more bulky

Synthesis and self-assembly of 1-deoxyglucose derivatives as low molecular weight organogelators

• Guijun Wang,
• Hao Yang,
• Sherwin Cheuk and
• Sherman Coleman

Beilstein J. Org. Chem. 2011, 7, 234–242, doi:10.3762/bjoc.7.31

• class of small molecules that can form reversible supramolecular gels in organic solvents or aqueous solutions [1][2][3][4][5][6][7][8][9]. Non-covalent interactions such as hydrogen bonding, hydrophobic interactions, and π–π stacking are the main driving forces for the self-assembly of the gelators

• gelators for water or aqueous ethanol mixtures. The monoesters presumably form an extended hydrogen bonding array between the ring oxygen and the free hydroxy groups [36]. For these compounds, the main forces that influence gelation include phenyl ring π–π interactions, hydrogen bonding, and hydrophobic

• interactions of the acyl chains, etc. To further understand the structural influence of the anomeric position of the sugar headgroup on self-assembly, we synthesized analogs using head group 8 [38] (Figure 2), in which the anomeric methoxy group was replaced with a hydrogen atom and contained a similar series

Expanding the gelation properties of valine-based 3,5-diaminobenzoate organogelators with N-alkylurea functionalities

• Hak-Fun Chow and
• Chin-Ho Cheng

Beilstein J. Org. Chem. 2010, 6, 1015–1021, doi:10.3762/bjoc.6.114

• to possess gelating ability that covered a wider range of organic solvents, including alcoholic, aromatic, alicyclic hydrocarbon and polar solvents. Furthermore, attachment of longer aliphatic chains not only enhanced hydrophobic interactions between the organogelators, but also prevented

Differences between β-Ala and Gly-Gly in the design of amino acids-based hydrogels

• Andreea Pasc,
• Firmin Obounou Akong,
• Sedat Cosgun and
• Christine Gérardin

Beilstein J. Org. Chem. 2010, 6, 973–977, doi:10.3762/bjoc.6.109

• properties were related to hydrogen bonding, hydrophobic interactions and π-π stacking. Herein, β-Ala-His-EO2-Alk was fully characterised by FT-IR, NMR, SAXS and SEM and the gelation mechanism is discussed. It appears that the number of amide groups determines the self-assembling behaviour into 1D or 2D/3D

• solvents, and a hydrophobic domain for van der Waals or hydrophobic interactions (Figure 1). They are able to entrap a large number of solvent molecules per one gelator molecule. Herein the gelators were designed as AA-His-EO2-Alk, bearing i) an hydrophobic alkyl group, ii) a polar peptide group with