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Pengyu Li, Qianfang Yao, Baozhong Lü, Guiping Ma, Meizhen Yin
A photoresponsive host-guest supramolecular complex (WP5⊃G) constructed by water-soluble pillar[5]arene (WP5) and spiropyran derivative (G) is presented. The spontaneous isomerization of G from spiropyran (SP) form to ring-opened merocyanine (MC) form happens either alone or in WP5⊃G in aqueous media. Irradiated by visible light, G can be converted into SP form completely and the hydrophilicity will be changed. G and WP5⊃G are both verified to self-assemble into nanospheres. Upon exposure to visible light, WP5⊃G reassemble into nanovesicles due to the change of supra-amphiphilicity, while G alone does not have this transition...
May 22, 2018: Macromolecular Rapid Communications
Hao Jiang, Martin Ehlers, Xiao-Yu Hu, Elio Zellermann, Carsten Schmuck
Peptide amphiphiles capable of assembling into multidimensional nanostructures have attracted much attention over the past decade due to their potential applications in materials science. Herein, a novel diacetylene-derived peptide gemini amphiphile with a fluorenylmethyloxycarbonyl (Fmoc) group at the N-terminus is reported to hierarchically assemble into spherical micelles, one-dimensional nanorods, two-dimensional foamlike networks and lamellae. Solvent polarity shows a remarkable effect on the self-assembled structures by changing the balance of four weak noncovalent interactions (hydrogen-bonding, π-π stacking, hydrophobic interaction, and electrostatic repulsion)...
May 22, 2018: Soft Matter
Darcy S Davidson, Anne M Brown, Justin A Lemkul
Pathological aggregation of amyloid-forming proteins is a hallmark of a number of human diseases, including Alzheimer's, type 2 diabetes, Parkinson's, and more. Despite having very different primary amino acid sequences, these amyloid proteins form similar supramolecular, fibril structures that are highly resilient to physical and chemical denaturation. To better understand the structural stability of disease-related amyloids and to gain a greater understanding of factors that stabilize functional amyloid assemblies, insights into tertiary and quaternary interactions are needed...
May 18, 2018: Journal of Molecular Biology
Yi-Han Ting, Hsuan-Ju Chen, Wan-Jung Cheng, Jia-Cherng Horng
Collagen-related materials have many potential biomedical applications because of their high biocompatibility and biodegradability. Designed collagen-mimetic peptides (CMPs) could self-assemble into supramolecular structures via a variety of interactions. In particular, metal-ligand interactions can induce microscale sizes of collagen assemblies. Our previous study also successfully applied metal-histidine coordination method to promote the self-assembly of CMPs into micrometers of constructs. In an effort to broaden the metal-induced strategies on assembling designed CMPs and explore the new insights into their assembly process, herein we designed and synthesized a series of short CMPs with one or more histidine residues incorporated into the peptides and used Zn(II) to induce the formation of collagen assembled microstructures...
May 21, 2018: Biomacromolecules
Koji Miki, Kenzo Saiki, Tomokazu Umeyama, Jinseok Baek, Takeru Noda, Hiroshi Imahori, Yuta Sato, Kazu Suenaga, Kouichi Ohe
Carbon nanotubes (CNTs) interlocked by cyclic compounds through supramolecular interaction are promising rotaxane-like materials applicable as 2D and 3D networks of nanowires and disease-specific theranostic agents having multifunctionalities. Supramolecular complexation of CNTs with cyclic compounds in a "ring toss'' manner is a straightforward method to prepare interlocked CNTs; however, to date, this has not been reported on. Here, the "ring toss" method to prepare interlocked CNTs by using π-conjugated carbon nanorings: [8]-, [9]-, and [10]cycloparaphenyleneacetylene (CPPA) is reported...
May 21, 2018: Small
Suchita Prasad, Katharina Achazi, Boris Schade, Rainer Haag, Sunil K Sharma
Herein, a new series of non-ionic dendritic and carbohydrate based amphiphiles is synthesized employing biocompatible starting materials and studied for supramolecular aggregate formation in aqueous solution. The dendritic amphiphiles 12 and 13 possessing poly(glycerol) [G2.0] as hydrophilic unit and C-10 and C-18 hydrophobic alkyl chains, respectively, exhibit low critical aggregation concentration (CAC) in the order of 10-5 m and hydrodynamic diameters in the 8-10 nm range and supplemented by cryogenic transmission electron microscopy...
May 21, 2018: Macromolecular Bioscience
Siying Xie, Shanshan Wu, Sihan Bao, Yanqiu Wang, Yongtai Zheng, Danfeng Deng, Liping Huang, Lingling Zhang, Myongsoo Lee, Zhegang Huang
Despite recent advances in the porous materials for efficient removal of dissolved organic pollutants from water, the regeneration of porous characteristics for reuse with preventing secondary contamination remains a challenge. Here, novel supramolecular absorbents with hydrophobic pore are prepared by the self-assembly of propeller-shaped aromatic amphiphiles. The assembly of folded propeller provides a mesoporous environment within aromatic segments, which is suitable for the removal of organic pollutants from waste water...
May 21, 2018: Advanced Materials
Lei Zhang, Nadiia Pasthukova, Yifan Yao, Xiaolan Zhong, Egon Pavlica, Gvido Bratina, Emanuele Orgiu, Paolo Samorì
Self-standing nanostructures are of fundamental interest in materials science and nanoscience and are widely used in (opto-)electronic and photonic devices as well as in micro-electromechanical systems. To date, large-area and self-standing nanoelectrode arrays assembled on flexible substrates have not been reported. Here the fabrication of a hollow nanomesh scaffold on glass and plastic substrates with a large surface area over 1 mm2 and ultralow leakage current density (≈1-10 pA mm-2 @ 2 V) across the empty scaffold is demonstrated...
May 21, 2018: Advanced Materials
Ying-Ming Zhang, Ni-Yuan Zhang, Kui Xiao, Yu Liu, Qilin Yu
The design and construction of multistimuli-responsive supramolecular nanoassemblies that can mimic and regulate the fundamental biological processes has become a focus of interest in supramolecular chemistry. In this work, a perfect combination has been achieved between naturally occurring microtubule and artificially macrocyclic receptor. The self-assembling morphology of microtubules can be photo-tuned by the host-guest interaction of paclitaxel-modified β-cyclodextrin (PTX-CD) and photochromic arylazopyrazole (PTX-AAP)...
May 20, 2018: Angewandte Chemie
J Vázquez, V Sindelar
Hydrogen sulfide (H2S) has become an important target for research due to its physiological properties as well as its potential applications in medicine. In this work, supramolecular binding of sulfide (S2-) and hydrosulfide (HS-) anions in water is presented for the first time. Bambusurils were used to slow down the release of these anions in water.
May 21, 2018: Chemical Communications: Chem Comm
Michal Baram, Sharon Gilead, Ehud Gazit, Yifat Miller
Insulin is a key regulatory polypeptide that is secreted from pancreatic β-cells and has several important effects on the synthesis of lipids, regulation of enzymatic activities, blood glucose levels and the prevention of hyperglycemia. Insulin was demonstrated to self-assemble into ordered amyloid fibrils upon repeated injections, although the possible biological significance of the supramolecular structures is enigmatic. Amylin is also an amyloidogenic polypeptide that is secreted from pancreatic β-cells and plays an important role in glycemic regulation preventing post-prandial spikes in blood glucose levels...
May 14, 2018: Chemical Science
Vargini Thangavadivale, Pedro M Aguiar, Naseralla A Jasim, Sarah J Pike, Dan A Smith, Adrian C Whitwood, Lee Brammer, Robin N Perutz
The syntheses of three series of complexes designed with self-complementary motifs for formation of halogen bonds between an iodotetrafluorophenyl ligand and a halide ligand at square-planar nickel are reported, allowing structural comparisons of halogen bonding between all four halides C6 F4 I···X-Ni (X = F, Cl, Br, I). In the series trans -[NiX(2,3,5,6-C6 F4 I)(PEt3 )2 ] 1pX and trans -[NiX(2,3,4,5-C6 F4 I)(PEt3 )2 ] (X = F, Cl, Br, I) 1oX , the iodine substituent on the benzene ring was positioned para and ortho to the metal, respectively...
April 21, 2018: Chemical Science
Lucas Carreras, Marta Serrano-Torné, Piet W N M van Leeuwen, Anton Vidal-Ferran
The use of halogen bonding as a tool to construct a catalyst backbone is reported. Specifically, pyridyl- and iodotetrafluoroaryl-substituted phosphines were assembled in the presence of a rhodium(i) precursor to form the corresponding halogen-bonded complex XBphos-Rh . The presence of fluorine substituents at the iodo-containing supramolecular motif was not necessary for halogen bonding to occur due to the template effect exerted by the rhodium center during formation of the halogen-bonded complex. The halogen-bonded supramolecular complexes were successfully tested in the catalytic hydroboration of terminal alkynes...
April 21, 2018: Chemical Science
Hayato Ouchi, Takahiro Kizaki, Masaki Yamato, Xu Lin, Nagahiro Hoshi, Fabien Silly, Takashi Kajitani, Takanori Fukushima, Ken-Ichi Nakayama, Shiki Yagai
Helical self-assembly of functional π-conjugated molecules offers unique photochemical and electronic properties in the spectroscopic level, but there are only a few examples that demonstrate their positive impact on the optoelectronic device level. Here, we demonstrate that hydrogen-bonded tapelike supramolecular polymers of a barbiturated oligo(alkylthiophene) show notable improvement in their photovoltaic properties upon organizing into helical nanofibers. A tapelike hydrogen-bonded supramolecular array of barbiturated oligo(butylthiophene) molecules was directly visualized by STM at a liquid-solid interface...
April 21, 2018: Chemical Science
Zhenzhong Lu, Harry G W Godfrey, Ivan da Silva, Yongqiang Cheng, Mathew Savage, Pascal Manuel, Svemir Rudić, Anibal J Ramirez-Cuesta, Sihai Yang, Martin Schröder
Fine tuning of host-guest supramolecular interactions in porous systems enables direct control over the properties of functional materials. We report here a modification of hydrogen bonding and its effect on guest binding in a pair of redox-active metal-organic frameworks (MOFs). Oxidation of MFM-300(VIII ) {[VIII2(OH)2 (L)], LH4 = biphenyl-3,3',5,5'-tetracarboxylic acid} is accompanied by deprotonation of the bridging hydroxyl groups to afford isostructural MFM-300(VIV ), [VIV2O2 (L)]. The precise role of the hydroxyl groups, O -carboxylate centres and π-π interactions in the supramolecular binding of C2 hydrocarbons in these materials has been determined using neutron diffraction and inelastic neutron scattering, coupled with DFT modelling...
April 7, 2018: Chemical Science
Sarah H Hewitt, Andrew J Wilson
Dynamic combinatorial chemistry (DCC) represents an approach, whereby traditional supramolecular scaffolds used for protein surface recognition might be exploited to achieve selective high affinity target recognition. Synthesis, in situ screening and amplification under selection pressure allows the generation of ligands, which bear different moieties capable of making multivalent non-covalent interactions with target proteins. Generic tetracarboxyphenyl porphyrin scaffolds bearing four hydrazide moieties have been used to form dynamic combinatorial libraries (DCLs) using aniline-catalyzed reversible hydrazone exchange reactions, in 10 % DMSO, 5 mm NH4 OAc, at pH 6...
April 30, 2018: European Journal of Organic Chemistry
Margarita Leyva-Leyva, Alejandro Sandoval, Ricardo Felix, Ricardo González-Ramírez
Dystrophin is a cytoskeleton-linked membrane protein that binds to a larger multiprotein assembly called the dystrophin-associated glycoprotein complex (DGC). The deficiency of dystrophin or the components of the DGC results in the loss of connection between the cytoskeleton and the extracellular matrix with significant pathophysiological implications in skeletal and cardiac muscle as well as in the nervous system. Although the DGC plays an important role in maintaining membrane stability, it can also be considered as a versatile and flexible molecular complex that contribute to the cellular organization and dynamics of a variety of proteins at specific locations in the plasma membrane...
May 19, 2018: Journal of Membrane Biology
Mathilde Champeau, Valéria Póvoa, Lucas Militão, Flávia Cabrini, Guilherme F Picheth, Florian Meneau, Carlos P Jara, Eliana P de Araujo, Marcelo G de Oliveira
Topical nitric oxide (NO) delivery has been shown to accelerate wound healing. However, delivering NO to wounds at appropriate rates and doses requires new biomaterial-based strategies. Here, we describe the development of supramolecular interpolymer complex hydrogels comprising PEO-PPO-PEO (F127) micelles embedded in a poly(acrylic acid) (PAA) matrix, with S-nitrosoglutathione (GSNO) molecules dissolved in the hydrophilic domain. We show that PAA:F127/GSNO hydrogels start releasing NO upon hydration at rates controlled by their rates of water absorption...
May 16, 2018: Acta Biomaterialia
Aisen Li, Ping Li, Yijia Geng, Shuping Xu, Houyu Zhang, Haining Cui, Weiqing Xu
The luminescence and structural changes of 4, 4'-bipyridine in the crystal and powder forms under the effect of high pressure applied by a diamond anvil cell has been investigated through the fluorescence and Raman spectroscopies. In its single crystal structure, the 4, 4'-bipyridine molecules are paralleled arranged with the identifiable CH⋯N and π⋯π interactions among molecules. However, in the powder form, these intermolecular interactions nearly diminish. The 4, 4'-bipyridine crystal shows the obvious bathochromic-shifting of the emission band, which is different from the powder sample that displays a fixed luminescent band during compression...
May 4, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Sander J Wezenberg, Ben L Feringa
Stimuli-controlled motion at the molecular level has fascinated chemists already for several decades. Taking inspiration from the myriad of dynamic and machine-like functions in nature, a number of strategies have been developed to control motion in purely synthetic systems. Unidirectional rotary motion, such as is observed in ATP synthase and other motor proteins, remains highly challenging to achieve. Current artificial molecular motor systems rely on intrinsic asymmetry or a specific sequence of chemical transformations...
May 18, 2018: Nature Communications
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