The influence of intraannular templates on the liquid crystallinity of shape-persistent macrocycles

• Joscha Vollmeyer,
• Ute Baumeister and
• Sigurd Höger

Beilstein J. Org. Chem. 2014, 10, 910–920, doi:10.3762/bjoc.10.89

• appropriate guest molecules on this macrocycle template [7][8][9][10]. In solution, shape-persistent macrocycles aggregate into defined dimers or up to μm long fibers that can form gels (in solution) or can be casted to yield efficient sensor materials [11][12][13][14][15][16][17][18][19][20][21][22][23

Charge-transfer interaction mediated organogels from 18β-glycyrrhetinic acid appended pyrene

• Jun Hu,
• Jindan Wu,
• Qian Wang and
• Yong Ju

Beilstein J. Org. Chem. 2013, 9, 2877–2885, doi:10.3762/bjoc.9.324

• in the formation of CT gels is demonstrated through the formation of gels in a variety of solvents. Thermal stability, stoichiometry, scanning electron microscopy (SEM), optical micrographs, and circular dichroism (CD) are performed on these CT gels to investigate their thermal and assembly

• properties. UV–vis, fluorescence, mass spectrometric as well as variable-temperature 1H NMR experiments on these gels suggest that the CT interaction is one of the major driving forces for the formation of these organogels. Keywords: charge transfer; glycyrrhetinic acid; organogel; self-assembly

• 30 min to see whether there was any flow of solvent. It showed that dark red CT gels (Figure 1c) were obtained in dimethyl sulfoxide (DMSO)/water and N,N-dimethylformamide (DMF)/water mixed solvents (Table 1, entries 3, 4 and 9, 10), but not in respective individual solvent system (DMSO, water or DMF

Self-assembly of 2,3-dihydroxycholestane steroids into supramolecular organogels as a soft template for the in-situ generation of silicate nanomaterials

• Valeria C. Edelsztein,
• Andrea S. Mac Cormack,
• Matías Ciarlantini and
• Pablo H. Di Chenna

Beilstein J. Org. Chem. 2013, 9, 1826–1836, doi:10.3762/bjoc.9.213

• .9.213 Abstract Supramolecular gels are an important and interesting class of soft materials that show great potential for many applications. Most of them have been discovered serendipitously, and understanding the supramolecular self-assembly that leads to the formation of the gel superstructure is the

• trap the solvent molecules in the supramolecular network to form supramolecular gels. The non-covalent nature of these interactions makes it possible for the supramolecular gel systems to achieve a reversible sol–gel phase transition by the simple application of an external stimulus. Intrinsically

• , supramolecular gels are thermosensitive and can be transformed reversibly to a fluid (sol) by heating. A small number of novel LMOGs, however, undergo a sol–gel transition as the temperature increases, which is called thermogelling [7]. Many other LMOG molecules form gels that are sensitive to other physical

Polymeric redox-responsive delivery systems bearing ammonium salts cross-linked via disulfides

• Christian Dollendorf,
• Martin Hetzer and
• Helmut Ritter

Beilstein J. Org. Chem. 2013, 9, 1652–1662, doi:10.3762/bjoc.9.189

• stability of the polymer discs even after the disulfide functionalities were cleaved. The polymer discs were immersed into distilled water and rheological measurements were conducted as described above. As expected, all samples showed the behavior of cross-linked gels and the values of the storage modulus G

Organotellurium-mediated living radical polymerization under photoirradiation by a low-intensity light-emitting diode

• Yasuyuki Nakamura and
• Shigeru Yamago

Beilstein J. Org. Chem. 2013, 9, 1607–1612, doi:10.3762/bjoc.9.183

• been widely employed in conventional radical polymerization for various applications such as coatings, adhesives, gels and microelectronics [4][5][6][7]. The major motivation for the utilization of photochemistry in LRP is that it enables the dormant species to be activated under mild thermal

Aqueous reductive amination using a dendritic metal catalyst in a dialysis bag

• Jorgen S. Willemsen,
• Jan C. M. van Hest and
• Floris P. J. T. Rutjes

Beilstein J. Org. Chem. 2013, 9, 960–965, doi:10.3762/bjoc.9.110

• to incomplete conversions. Incompatible catalysts can be physically separated in various ways, e.g., by applying biphasic reaction conditions [10], membrane reactors [11] or sol–gels [12]. Another way to circumvent incompatibility problems is to achieve compartmentalization by attaching the actual

The conjugation of nonsteroidal anti-inflammatory drugs (NSAID) to small peptides for generating multifunctional supramolecular nanofibers/hydrogels

• Jiayang Li,
• Yi Kuang,
• Junfeng Shi,
• Yuan Gao,
• Jie Zhou and
• Bing Xu

Beilstein J. Org. Chem. 2013, 9, 908–917, doi:10.3762/bjoc.9.104

•  1) [64], suggesting that the matrices of gels have good tolerance to the external shear force. In addition, the storage moduli of all these hydrogels in the frequency sweep are comparable with storage moduli of the constant region in the strain sweep. Hydrogel 1b has the highest G' (5.3 × 104 Pa

• (Figure S4, Supporting Information File 1) [64], indicating that these molecules self-assemble to re-establish the network rapidly after deformation caused by a perturbation. To characterize the recovery properties of the gels of 1a and 1d, we first measure the G' values of the gels at 0.4% strain for 10

• min to obtain their original storage moduli, and then apply a large-amplitude oscillation with 100% strain and 6.28 rad/s angular frequency to perturb the structure of the hydrogels for 10 min. After removing this large amplitude of oscillation, we immediately measure the storage moduli of the gels at

Synthesis and evaluation of cell-permeable biotinylated PU-H71 derivatives as tumor Hsp90 probes

• Tony Taldone,
• Anna Rodina,
• Erica M. DaGama Gomes,
• Matthew Riolo,
• Hardik J. Patel,
• Raul Alonso-Sabadell,
• Danuta Zatorska,
• Maulik R. Patel,
• Sarah Kishinevsky and
• Gabriela Chiosis

Beilstein J. Org. Chem. 2013, 9, 544–556, doi:10.3762/bjoc.9.60

•  2d, bottom panel Raf-1 blot). The Coomassie blue stained gels of these pull-downs showed a single band at approximately 90 kDa for derivatives 2g, 2i, 2d, 2f and 2h (Figure 2d), which was competitively blocked by pretreatment of cells with a soluble ligand (Figure 2e) indicating concomitant binding

• 120 μL. Samples were incubated at 4 °C for 1 h, washed five times with the lysis buffer (or high salt buffer containing 1 M NaCl added to the lysis buffer) and applied to SDS-PAGE. Gels were stained with Coomassie blue (BioRad) according to the manufacturer's instructions. Competitive binding. K562

Zanthoxoaporphines A–C: Three new larvicidal dibenzo[de,g]quinolin-7-one alkaloids from Zanthoxylum paracanthum (Rutaceae)

• Fidelis N. Samita,
• Louis P. Sandjo,
• Isaiah O. Ndiege,
• Ahmed Hassanali and
• Wilber Lwande

Beilstein J. Org. Chem. 2013, 9, 447–452, doi:10.3762/bjoc.9.47

• electronic apparatus and are uncorrected. 1D and 2D NMR spectra were carried out on a Bruker DRX-300 MHz and Bruker 600 MHz instrument, respectively. Silica gels 60H (particle size < 45 µm), GF254 and 60A (size 70–200 µm) were used to perform, respectively, flash chromatography, thin-layer chromatography

A peptidic hydrogel that may behave as a “Trojan Horse”

• Nicola Castellucci,
• Giorgio Sartor,
• Natalia Calonghi,
• Carola Parolin,
• Giuseppe Falini and
• Claudia Tomasini

Beilstein J. Org. Chem. 2013, 9, 417–424, doi:10.3762/bjoc.9.44

• been reported [11]. In the gels, noncovalent, weak interactions between the individual LMWHG molecules hold the fibers together. The gel-forming characteristics of LMWHGs can be controlled by altering the strength of these interactions, as illustrated by the thermal reversibility of the gel–sol

• samples easily form gels, as shown in Table 1. They were prepared, by dissolving the gelator in a test tube (8 mm wide) containing ethanol. The mixture was shaken for a few minutes by hand, then water was added and the tube was sonicated for fifteen minutes at room temperature and left to stand for an

• additional 16 hours for the gel formation. Interestingly, these LMWHG having hydrophilic carboxylic acid moieties, located in the hydrophilic part of the molecule, provide a reversible response to changes in pH. Indeed they are in the gel state up to pH ≈ 9. At higher pH, the gels undergo conversion to the

Spin state switching in iron coordination compounds

• Philipp Gütlich,
• Ana B. Gaspar and
• Yann Garcia

Beilstein J. Org. Chem. 2013, 9, 342–391, doi:10.3762/bjoc.9.39

Cyclodextrin-based nanosponges as drug carriers

• Francesco Trotta,
• Marco Zanetti and
• Roberta Cavalli

Beilstein J. Org. Chem. 2012, 8, 2091–2099, doi:10.3762/bjoc.8.235

• just 9.9 μg/ml resulting in low bioavailability. The formation of a ternary complex of telmisartan with nanosponges and NaHCO3 was seen to synergistically enhance the dissolution rate of telmisartan [47]. Topical delivery systems Nanosponges can be used in gels or creams for topical application. In one

Polysiloxane ionic liquids as good solvents for β-cyclodextrin-polydimethylsiloxane polyrotaxane structures

• Narcisa Marangoci,
• Rodinel Ardeleanu,
• Laura Ursu,
• Constanta Ibanescu,
• Maricel Danu,
• Mariana Pinteala and
• Bogdan C. Simionescu

Beilstein J. Org. Chem. 2012, 8, 1610–1618, doi:10.3762/bjoc.8.184

• supermolecules formed by ILs with different host molecules), leading to interesting phenomena, properties and applications [7][8][9][10][11][12]. This includes the dissolution of cellulose and cyclodextrins (CDs) with ILs [12], synthesis of ILs containing slide-ring gels [7], synthesis of IL-CD inclusion

Supramolecular hydrogels formed from poly(viologen) cross-linked with cyclodextrin dimers and their physical properties

• Yoshinori Takashima,
• Yang Yuting,
• Miyuki Otsubo,
• Hiroyasu Yamaguchi and
• Akira Harada

Beilstein J. Org. Chem. 2012, 8, 1594–1600, doi:10.3762/bjoc.8.182

• of functional soft materials has attracted much attention due to the numerous practical applications [1][2][3]. Typically, soft materials fall into one of two types of gels: physical gels and chemical gels [4][5][6][7][8][9]. Recently, topological cross-linked polyrotaxanes have been identified as

• tertiary gels, which should create a new paradigm in materials science [10]. Polyrotaxanes form topological gels, because the rotor molecules, which act as cross-linkers, slide on the axial polymer chain. In contrast, chemical gels do not exhibit cross-linker slippage. Previously, there have been some

• Voigt Model. G'' relaxes as the frequency increases. However, the hydrogel does not relax (G' > G'') in the frequency range 0.01–10 rad·s−1, indicating a self-standing gel. This behavior are similar to chemically cross-linked gels even though the α,α-CD dimer/VP hydrogel is topologically cross-linked

Interaction of cyclodextrins with pyrene-modified polyacrylamide in a mixed solvent of water and dimethyl sulfoxide as studied by steady-state fluorescence

• Akihito Hashidzume,
• Yongtai Zheng and
• Akira Harada

Beilstein J. Org. Chem. 2012, 8, 1312–1317, doi:10.3762/bjoc.8.150

• ][36]. Recently, we have demonstrated this selectivity switching on macroscopic molecular recognition for polyacrylamide-based gels carrying pyrenyl (Py) and CD residues, by changing the composition of a mixed solvent of water and dimethyl sulfoxide (DMSO) [37]. In the present study, the interaction of

Recyclable fluorous cinchona alkaloid ester as a chiral promoter for asymmetric fluorination of β-ketoesters

• Wen-Bin Yi,
• Xin Huang,
• Zijuan Zhang,
• Dian-Rong Zhu,
• Chun Cai and
• Wei Zhang

Beilstein J. Org. Chem. 2012, 8, 1233–1240, doi:10.3762/bjoc.8.138

• quinine with a fluorous acid chloride (Scheme 1). This compound was easily purified by fluorous-solid phase extraction (F-SPE) with a cartridge charged with fluorous silica gels [29][30]. It is stable in air and soluble in solvents such as CH2Cl2, CH3OH, and CH3CN. With the fluorous quinine ester C-1 in

Control over molecular motion using the cis–trans photoisomerization of the azo group

• Estíbaliz Merino and
• María Ribagorda

Beilstein J. Org. Chem. 2012, 8, 1071–1090, doi:10.3762/bjoc.8.119

• conformational changes in polymers. There may also be variations in the organization of large assemblies of molecules in gels or liquid crystals. When polarized light is used, the photoisomerization often induces a reorganization of chromophores that can be reflected in the circular dichroism spectra. The basic

An easily accessible sulfated saccharide mimetic inhibits in vitro human tumor cell adhesion and angiogenesis of vascular endothelial cells

• Grazia Marano,
• Claas Gronewold,
• Martin Frank,
• Anette Merling,
• Christian Kliem,
• Sandra Sauer,
• Manfred Wiessler,
• Eva Frei and
• Reinhard Schwartz-Albiez

Beilstein J. Org. Chem. 2012, 8, 787–803, doi:10.3762/bjoc.8.89

• by Lowry’s method) were separated under nonreducing conditions in a 7.5% sodium dodecyl sulfate-polyacrylamide gel (SDS-PAGE) polymerized together with 0.1% gelatin. After electrophoresis, gels were washed twice in 2.5% Triton X-100 and four times in H2O before overnight incubation in gelatinase

Mutational analysis of a phenazine biosynthetic gene cluster in Streptomyces anulatus 9663

• Orwah Saleh,
• Katrin Flinspach,
• Lucia Westrich,
• Andreas Kulik,
• Bertolt Gust,
• Hans-Peter Fiedler and
• Lutz Heide

Beilstein J. Org. Chem. 2012, 8, 501–513, doi:10.3762/bjoc.8.57

• . Lysozyme was from Boehringer Ingelheim, Heidelberg, Germany. Genetic procedures Standard methods for DNA isolation and manipulation were performed as described by Kieser et al. [36] and Sambrook et al. [39]. DNA fragments were isolated from agarose gels by using a PCR purification kit (Amersham Biosciences

Azobenzene dye-coupled quadruply hydrogen-bonding modules as colorimetric indicators for supramolecular interactions

• Yagang Zhang and
• Steven C. Zimmerman

Beilstein J. Org. Chem. 2012, 8, 486–495, doi:10.3762/bjoc.8.55

• -modified PBA ranged from viscous liquids to gels depending on the loading of UPy groups on the polymer backbone (Figure 5). The supramolecular coupling of DAN and DeUG units and DAN and UPy units has been well studied. Thus, the association constant (Kassoc) for the DAN–DeUG heterocomplex was measured as

Protonation and deprotonation induced organo/hydrogelation: Bile acid derived gelators containing a basic side chain

• Uday Maitra and
• Arkajyoti Chakrabarty

Beilstein J. Org. Chem. 2011, 7, 304–309, doi:10.3762/bjoc.7.40

• -assembled structures form mainly due to weak non-covalent interactions such as hydrogen-bonding, van der Waals forces, π–π interactions, charge-transfer interactions etc. in organogels, whereas, in aqueous gels, the major driving force for aggregation is hydrophobic interaction [2]. A number of

• hydrogelators derived from the bile acid backbone have been described in the literature [3][4][5]. The earliest reports include sodium deoxycholate which forms a gel in water at pH 6.9 [6] and calcium cholate which gels water at pH 7 [7][8][9]. The facial amphiphilicity of the bile acid derivatives appears to

• , whereas when it was used as its iodide salt it formed strong gels in 1,2-dichlorobenzene and chlorobenzene. To illustrate the acid-base switching of this gel, a simple experiment was designed to show the reversible switching from gel→sol→gel of 1 in 1,2-dichlorobenzene using cresol red sodium salt as the

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

• are an important class of molecules. The supramolecular gels formed by carbohydrate derived low molecular weight gelators are interesting soft materials that show great potential for many applications. Previously, we have synthesized a series of methyl 4,6-O-benzylidene-α-D-glucopyranoside derivatives

• 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

• into 3-dimensional networks. The resulting gels may find applications as soft materials for drug delivery, enzyme immobilization, scaffolds for tissue engineering, etc. [10][11][12][13][14]. The structures of LMWGs span a diverse range; carbohydrates have frequently been used in the synthesis of LMWGs

Amphiphilic dendritic peptides: Synthesis and behavior as an organogelator and liquid crystal

• Baoxiang Gao,
• Hongxia Li,
• Defang Xia,
• Sufang Sun and
• Xinwu Ba

Beilstein J. Org. Chem. 2011, 7, 198–203, doi:10.3762/bjoc.7.26

• bonds. The absorption intensity at 3081 cm−1 decreases in the organogelator which indicates the loss of hydrogen bonds. Hydrogen bonds as physical cross-linking points in these compounds are an essential factor for gelling. With more physical cross-linking points, compound G3 gels more easily. Compound

Exceptionally small supramolecular hydrogelators based on aromatic–aromatic interactions

• Junfeng Shi,
• Yuan Gao,
• Zhimou Yang and
• Bing Xu

Beilstein J. Org. Chem. 2011, 7, 167–172, doi:10.3762/bjoc.7.23

• properties. Notably, compound 6 can undergo cis/trans-isomerization upon UV irradiation. Keywords: aromatic–aromatic interaction; cinnamoyl; hydrogel; hydrogelator; supramolecular; Introduction Gels formed by three-dimensional, elastic networks to encapsulate a liquid [1], have many useful properties (e.g

• gel materials, research on supramolecular gels [14][15][16][17][18][19] has rapidly expanded. Amongst these, self-assembled oligopeptides [20][21][22][23], which self-assemble in water to form nanofibers and provide hydrogels for biomedical applications, have stimulated the recent research efforts on

• hydrogels. Compared with compound 3, compound 2 fails to form a gel due to the conjugation between the carbonyl group and the naphthyl group, which partial reduces the rotational freedom of the naphthyl group that is necessary for self-assembly. As shown in Table 1, all gels (gels I, II, III and IV formed

Gelation or molecular recognition; is the bis-(α,β-dihydroxy ester)s motif an omnigelator?

• Peter C. Griffiths,
• David W. Knight,
• Ian R. Morgan,
• Amy Ford,
• James Brown,
• Ben Davies,
• Richard K. Heenan,
• Stephen M. King,
• Robert M. Dalgliesh,
• John Tomkinson,
• Stuart Prescott,
• Ralf Schweins and
• Alison Paul

Beilstein J. Org. Chem. 2010, 6, 1079–1088, doi:10.3762/bjoc.6.123

• , raising interesting questions as to the mechanism of gelation. At gelator concentrations of 5–50 mg ml−1, gels were successfully formed in acetone, ethanol/water mixtures, toluene, cyclohexane and chloroform (the latter, albeit at a higher gelator concentration). A range of neutron techniques – in

• particular small-angle neutron scattering (SANS) – have been employed to probe the structure of a selection of these gels. The universality of gelation in a range of solvent types suggests the gelation mechanism is a feature of the bis-(α,β-dihydroxy ester) motif, with SANS demonstrating the presence of

• concentration indicating that the number of scatterers increases, leading to the stiffer gels implied by the concomitant increase in Tgel–sol observed. These gelators form gels in a wide range of solvents, a rather serendipitous and unusual discovery. It is that observation that is elaborated here, and in