Smart molecules for imaging, sensing and health (SMITH)

• Bradley D. Smith

Beilstein J. Org. Chem. 2015, 11, 2540–2548, doi:10.3762/bjoc.11.274

• many supramolecular chemistry labs around the world. In addition, the chapter provided a short summary of four emerging themes in biomolecule recognition that are likely to garner increased attention over the next decade; Logic Devices, Biomolecule Responsive Materials, Drug Delivery, and Biomolecule

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

• charged polymers and dendrimers. In order to use these SNPs for biomedical applications, in particular for drug delivery, a stimulus-responsive self-assembled system is desired for controlled cargo release. Ferrocene (Fc) is a ubiquitous redox-responsive molecule that is associated with a reversible one

Preparation of Pickering emulsions through interfacial adsorption by soft cyclodextrin nanogels

• Shintaro Kawano,
• Toshiyuki Kida,
• Mitsuru Akashi,
• Hirofumi Sato,
• Motohiro Shizuma and
• Daisuke Ono

Beilstein J. Org. Chem. 2015, 11, 2355–2364, doi:10.3762/bjoc.11.257

• property of CD nanogels on the droplet surface has great potential to become new microcapsule building blocks with porous surfaces. These microcapsules may act as stimuli-responsive nanocarriers and nanocontainers. Keywords: crosslinked cyclodextrin polymer; interfacial adsorption; nanogel; Pickering

• crosslinked polymers, have recently been demonstrated as Pickering emulsifiers with pH or thermo-responsive properties [7][8][9]. Such emulsions have potential in pharmaceutical, food, and cosmetic products. Moreover, emulsions stabilized by stimuli-responsive soft microgels should be applicable as templates

• new building blocks for microcapsules with porous surfaces and stimuli-responsive nanocarriers in storage and/or release systems. Experimental Materials Heptakis(2,6-di-O-methyl)-β-cyclodextrin (DM-β-CD) was purchased from Nacalai Tesque, Inc. (Japan). DM-β-CD was vacuum dried at 80 °C overnight prior

Life lessons

• Jonathan R. Nitschke

Beilstein J. Org. Chem. 2015, 11, 2350–2354, doi:10.3762/bjoc.11.256

• ][15][16][17][18][19][20][21][22][23][24][25]. Over the past few years, we have developed a series of new functional structures. A leitmotiv of my group’s work is the integration of a new class of hollow container molecules, invented by my group, into complex and dynamically-responsive systems and

Self-assemblies of γ-CDs with pentablock copolymers PMA-PPO-PEO-PPO-PMA and endcapping via atom transfer radical polymerization of 2-methacryloyloxyethyl phosphorylcholine

• Jing Lin,
• Tao Kong,
• Lin Ye,
• Ai-ying Zhang and
• Zeng-guo Feng

Beilstein J. Org. Chem. 2015, 11, 2267–2277, doi:10.3762/bjoc.11.247

• compared with PPO or PMAA), respectively, these unmatched PRs possess the potential to be applied as dynamic-responsive materials, carriers for controlled drug release, biosensors and catalysts. Poly(methyl acrylate) (PMA) prepared via ATRP of methyl acrylate (MA) is a typical hydrophobic polymer with a

• PR supramolecular polymers show potential as dynamic-responsive materials, carriers for controlled drug release, biosensors and catalysts. Experimental Materials PPO-PEO-PPO with a central block of 90 PEO units and two flank blocks of 5 PPO units was supplied by Zhejiang Huangma Chemical Industry

Hexacoordinate Ru-based olefin metathesis catalysts with pH-responsive N-heterocyclic carbene (NHC) and N-donor ligands for ROMP reactions in non-aqueous, aqueous and emulsion conditions

• Shawna L. Balof,
• K. Owen Nix,
• Matthew S. Olliff,
• Sarah E. Roessler,
• Arpita Saha,
• Kevin B. Müller,
• Ulrich Behrens,
• Edward J. Valente and
• Hans-Jörg Schanz

Beilstein J. Org. Chem. 2015, 11, 1960–1972, doi:10.3762/bjoc.11.212

• , OR 97203, USA 10.3762/bjoc.11.212 Abstract Three new ruthenium alkylidene complexes (PCy3)Cl2(H2ITap)Ru=CHSPh (9), (DMAP)2Cl2(H2ITap)Ru=CHPh (11) and (DMAP)2Cl2(H2ITap)Ru=CHSPh (12) have been synthesized bearing the pH-responsive H2ITap ligand (H2ITap = 1,3-bis(2’,6’-dimethyl-4’-dimethylaminophenyl

• )-4,5-dihydroimidazol-2-ylidene). Catalysts 11 and 12 are additionally ligated by two pH-responsive DMAP ligands. The crystal structure was solved for complex 12 by X-ray diffraction. In organic, neutral solution, the catalysts are capable of performing standard ring-opening metathesis polymerization

• catalysts or systems where the activity can be controlled by external stimuli [38][39][40][41][42][43][44]. In metathesis, pH is a very straightforward stimulus that can fulfill two independent functions for catalysts bearing pH-responsive ligands resulting in metathesis activation [45][46][47][48][49][50

Synthesis, antimicrobial and cytotoxicity evaluation of new cholesterol congeners

• Mohamed Ramadan El Sayed Aly,
• Hosam Ali Saad and
• Shams Hashim Abdel-Hafez

Beilstein J. Org. Chem. 2015, 11, 1922–1932, doi:10.3762/bjoc.11.208

• their immunostimulant activities [21]. Finally, the ability of cholesterol derivatives to self-assembly and gelation as supramolecular gels was reviewed [22]. They are beneficially applicable in materials science, reaction media, sensing and responsive materials, energy supply, biomedicine, and tissue

Cross-metathesis of polynorbornene with polyoctenamer: a kinetic study

• Yulia I. Denisova,
• Maria L. Gringolts,
• Alexander S. Peregudov,
• Liya B. Krentsel,
• Ekaterina A. Litmanovich,
• Arkadiy D. Litmanovich,
• Eugene Sh. Finkelshtein and
• Yaroslav V. Kudryavtsev

Beilstein J. Org. Chem. 2015, 11, 1796–1808, doi:10.3762/bjoc.11.195

• easily cleavable moieties in their backbone [4][5]. It aims at stimuli-responsive, intelligent polymeric materials, the structure and properties of which can be precisely controlled by adjusting temperature, pH or by introducing low molecular additives. Much less is known about the possibility of monomer

Tetrathiafulvalene-based azine ligands for anion and metal cation coordination

• Awatef Ayadi,
• Aziz El Alamy,
• Olivier Alévêque,
• Magali Allain,
• Nabil Zouari,
• Mohammed Bouachrine and
• Abdelkrim El-Ghayoury

Beilstein J. Org. Chem. 2015, 11, 1379–1391, doi:10.3762/bjoc.11.149

• -responsive receptors for neutral and/or charged guest sensing applications have been prepared [18][19][20][21][22]. On this ground, chemosensors capable of recognizing anionic and/or cationic species constitute an important area of increasing research in supramolecular chemistry, considering the ubiquitous

Impact of multivalent charge presentation on peptide–nanoparticle aggregation

• Daniel Schöne,
• Boris Schade,
• Christoph Böttcher and
• Beate Koksch

Beilstein J. Org. Chem. 2015, 11, 792–803, doi:10.3762/bjoc.11.89

• charged gold nanoparticles. The overall primary sequence of VW05 was designed to provide a pH-responsive aggregation of nanoparticles based on electrostatic interactions. Accordingly, a scrambled version of VW05 with the same amino acid composition and net charge did not show any evidence for

Regulation of integrin and growth factor signaling in biomaterials for osteodifferentiation

• Qiang Wei,
• Theresa L. M. Pohl,
• Anja Seckinger,
• Joachim P. Spatz and
• Elisabetta A. Cavalcanti-Adam

Beilstein J. Org. Chem. 2015, 11, 773–783, doi:10.3762/bjoc.11.87

• have been mapped [7][35]. Generally, integrin–ligand interactions elicit the activation of focal adhesion kinase (FAK) and its downstream target-effectors [36]. FAK is a tyrosine kinase and embedded in focal adhesions, the distribution of which is responsive to cell adhesion and spreading. The integrin

Multivalent dendritic polyglycerolamine with arginine and histidine end groups for efficient siRNA transfection

• Fatemeh Sheikhi Mehrabadi,
• Hanxiang Zeng,
• Mark Johnson,
• Cathleen Schlesener,
• Zhibin Guan and
• Rainer Haag

Beilstein J. Org. Chem. 2015, 11, 763–772, doi:10.3762/bjoc.11.86

• ) Arg to His ratio, showed efficient siRNA transfection with minimal cytotoxicity (cell viability ≥ 90%) in NIH 3T3 cells line. We also demonstrated that the cytotoxicity of dPG-NH2 decreased as a result of amino acid functionalization. While the incorporation of both cationic (Arg) and pH-responsive

Glycodendrimers: tools to explore multivalent galectin-1 interactions

• Jonathan M. Cousin and
• Mary J. Cloninger

Beilstein J. Org. Chem. 2015, 11, 739–747, doi:10.3762/bjoc.11.84

• residues were present at each stage in the assay irrespective of the scaffold generation number, dose-responsive inhibition of galectin-1 mediated cancer cell adhesion was only observed with lactose functionalized G(3)-dendrimer 2 at these concentrations (Figure 7b, and representative images 7e–h, the dose

• -responsive curve for lower concentrations of 1 is provided in Supporting Information File 1). Nearly complete inhibition of cellular aggregation was observed with compound 2 at the highest concentration of 2. The inhibition observed with compounds 1 and 2 indicates that the smaller glycodendrimers are the

Synthesis and characterization of pH responsive D-glucosamine based molecular gelators

• Navneet Goyal,
• Hari P. R. Mangunuru,
• Bargav Parikh,
• Sonu Shrestha and
• Guijun Wang

Beilstein J. Org. Chem. 2014, 10, 3111–3121, doi:10.3762/bjoc.10.328

• naproxen from the pH responsive gels were also analyzed under acidic and neutral conditions. Our findings are useful for the design of novel triggered release self-assembling systems and can provide an insight into the influence of the the structure on gelation. Keywords: glucosamine; hydrogelators

• ; naproxen; organogelator; pH responsive; self-assembly; Introduction Low molecular weight gelators (LMWGs) have drawn great attention over the past few decades due to the formation of supramolecular structures and their potential applications as advanced materials [1][2][3][4][5][6][7]. LMWGs are also

• the controlled release of certain biological agents [17][18][19][20][21][22][23][24][25][26][27]. Molecular gelators containing photo or pH responsive functional groups are able to form multi-stimuli responsive gels. These resulting gels may find applications as advanced soft functional materials [28

Cyclodextrin–polysaccharide-based, in situ-gelled system for ocular antifungal delivery

• Anxo Fernández-Ferreiro,
• Noelia Fernández Bargiela,
• María Santiago Varela,
• Maria Gil Martínez,
• Maria Pardo,
• Antonio Piñeiro Ces,
• José Blanco Méndez,
• Miguel González Barcia,
• Maria Jesus Lamas and
• Francisco.J. Otero-Espinar

Beilstein J. Org. Chem. 2014, 10, 2903–2911, doi:10.3762/bjoc.10.308

• patient compliance and comfort [10]. Specifically, stimuli-responsive polymer hydrogels have recently attracted special attention as drug delivery systems due to their capacity to respond to changing environmental conditions such as ion composition, pH, temperature, presence of chemicals, or changes on

Preparation and evaluation of cyclodextrin polypseudorotaxane with PEGylated liposome as a sustained release drug carrier

• Kayoko Hayashida,
• Taishi Higashi,
• Daichi Kono,
• Keiichi Motoyama,
• Koki Wada and
• Hidetoshi Arima

Beilstein J. Org. Chem. 2014, 10, 2756–2764, doi:10.3762/bjoc.10.292

• various targeting-ligands such as antibodies, sugars and folic acid to LPs [30][31][32]. Recently, stimulus responsive LPs such as bubble LPs, pH responsive LPs and thermoresponsive LPs have been developed as smart drug carriers [33][34][35]. PEGylated LP (PEG-LP) is one of the most popular LP products

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

• ) (PDMAEMA) block (Scheme 1A, P1), allows for the self-assembly and controlled release by taking advantage of the amphiphilic structure and the stimuli-responsive property of PDMAEMA block, respectively. When the hyperbranched polycarbonsilane (HBPCSi) is grafted onto the side chain of PHEMA blocks (Scheme

• release was obtained by taking advantage of the stimuli-responsive property of the PDMAEMA segments. Furthermore, the cumulative amounts of LND released from DLMP1, DLMP2 and DLMP3 were only 18.4, 15.5, and 9.2%, respectively, within the release time of 48 h, indicating the clear sustained release

Synthesis of a resin monomer-soluble polyrotaxane crosslinker containing cleavable end groups

• Ji-Hun Seo,
• Shino Nakagawa,
• Koichiro Hirata and
• Nobuhiko Yui

Beilstein J. Org. Chem. 2014, 10, 2623–2629, doi:10.3762/bjoc.10.274

• disassembling of PRX by a cytoplasmic reductant such as glutathione. The characteristic property of cleavable PRXs may also be harnessed to develop a stimuli-responsive crosslinker to modulate the hardness of acrylic resins. Acrylic resins are irreversible photosetting polymers adopted to increase the

• , the introduction of a stimuli-responsive and degradable crosslinkable resin monomer into the composite resin, the hardness of the polymerized resin composite could be modulated under specific conditions. Because the degradable PRX structure is a suitable molecular platform for an efficient degradation

Synthesis and characterization of a hyper-branched water-soluble β-cyclodextrin polymer

• Francesco Trotta,
• Fabrizio Caldera,
• Roberta Cavalli,
• Andrea Mele,
• Carlo Punta,
• Lucio Melone,
• Franca Castiglione,
• Barbara Rossi,
• Monica Ferro,
• Vincenza Crupi,
• Domenico Majolino,
• Valentina Venuti and
• Dominique Scalarone

Beilstein J. Org. Chem. 2014, 10, 2586–2593, doi:10.3762/bjoc.10.271

• mg/mL) over a wide pH range. However, at a pH below 1 the protonation of carboxylic acid groups leads to a precipitate. As predictable, if neutral pH is restored, all the precipitated polymer is solubilized again. This behavior could be of interest in pH responsive drug delivery systems. In addition

Host–guest-driven color change in water: influence of cyclodextrin on the structure of a copper complex of poly((4-hydroxy-3-(pyridin-3-yldiazenyl)phenethyl)methacrylamide-co-dimethylacrylamide)

• Nils Retzmann,
• Gero Maatz and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 2480–2483, doi:10.3762/bjoc.10.259

• experiments. Keywords: cyclodextrin; copolymer; copper(II) sulfate; supramolecular; water complex; Introduction In recent years, the interest in stimuli-responsive polymers increased exponentially [1]. Many polymers have been described, showing sensitivity towards e.g. light, pH and heat [2][3][4

• -copper complexes in aqueous media. In result we could show that supramolecular structures and metal complexes open up a wide field for the development of novel stimuli-responsive polymer materials. We thus described that the simple addition of copper and γ-CD to a poly((4-hydroxy-3-(pyridin-3-yldiazenyl

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

• -covalent interactions stable yet reversible systems are generated, which are responsive to external stimuli. These advantages have made synthetic multivalent systems interesting for a broad field of applications. In the case of medicinal applications multivalent molecules have been used as inhibitors of

Photoswitchable precision glycooligomers and their lectin binding

• Daniela Ponader,
• Sinaida Igde,
• Marko Wehle,
• Katharina Märker,
• Mark Santer,
• David Bléger and
• Laura Hartmann

Beilstein J. Org. Chem. 2014, 10, 1603–1612, doi:10.3762/bjoc.10.166

• affinity towards PA-IL lectins on demand, we were intrigued in the ability of our light-responsive systems to work when immobilized on a surface. To this end we attached the photoswitchable precision glycooligomers directly to the SPR chip and performed a second set of lectin binding experiments using SPR

A promising cellulose-based polyzwitterion with pH-sensitive charges

• Thomas Elschner and
• Thomas Heinze

Beilstein J. Org. Chem. 2014, 10, 1549–1556, doi:10.3762/bjoc.10.159

• ., acid dissociation constants, isoelectric point and complexation, were investigated by potentiometric titration (pH), nephelometry, rheology and dynamic light-scattering. The formation of pH-responsive interpolyelectrolyte complexes applying polydiallyldimethylammonium chloride was preliminary studied

• titration (pH), nephelometry, rheology and dynamic light-scattering. Moreover, preliminary studies about stimuli-responsive interpolyelectrolyte complexes are presented. Results and Discussion Synthesis The synthesis of a novel polyzwitterion based on cellulose was performed by activation of the polymer

• of the cellulose derivatives. Acid dissociation constants, isoelectric point and complexation behavior are in good agreement and thus, a well characterized zwitterionic cellulose carbamate with excellent properties was discovered. Preliminary studies show the formation of pH-responsive

An economical and safe procedure to synthesize 2-hydroxy-4-pentynoic acid: A precursor towards ‘clickable’ biodegradable polylactide

• Quanxuan Zhang,
• Hong Ren and
• Gregory L. Baker

Beilstein J. Org. Chem. 2014, 10, 1365–1371, doi:10.3762/bjoc.10.139

• family of water-soluble and temperature responsive biodegradable PLA material with tunable lower critical solution temperature (LCST) in a range from 25 to 65 °C was obtained after ‘click’ grafting with a mixture of alkyl and PEG azides. Starting from the same precursor 1 [18], Yu and coworkers have

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

• synthesis of thermo-, oxidation- and cyclodextrin- (CD) responsive end-group-functionalized polymers, based on N,N-diethylacrylamide (DEAAm). In a classical free-radical chain transfer polymerization, using thiol-functionalized 4-alkylphenols, namely 3-(4-(1,1-dimethylethan-1-yl)phenoxy)propane-1-thiol and

• interactions in living systems [3][4]. Since then, the field of self-assembly through molecular recognition has attracted much attention also in the design of smart materials. In this context, cyclodextrins (CD) are of interest as ring shaped host molecules, e.g., for the design of stimuli-responsive hydrogels

• [5] or of optical sensors [6]. Certain stimuli-responsive materials are characterized by the presence of thioethers in the main chain. Tirelli et al. investigated the oxidation-responsive behavior of thioethers for biomedical applications [7][8][9][10]. The stimulus of these mostly poly(propylene