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https://www.readbyqxmd.com/read/28080045/crystal-engineering-of-hand-twisted-helical-crystals
#1
Subhankar Saha, Gautam R Desiraju
A strategy is outlined for the design of hand-twisted helical crystals. The starting point in the exercise is the one-directional (1D) plastic crystal, 1,4-dibromobenzene, which is then changed to a 1D elastic crystal, exemplified by 4-bromophenyl 4'-chlorobenzoate, by introduction of a molecular synthon -O-CO- in lieu of the supramolecular synthon Br•••Br in the precursor. The 1D elastic crystals are next modified to two-directional (2D) elastic crystals, of the type 4-bromophenyl 4'-nitrobenzoate where the halogen bonding and C-H•••O hydrogen bonding are well matched...
January 12, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28079357/tetra-carboxylated-azobenzene-polymer-supramolecular-assemblies-as-high-performance-multiresponsive-actuators
#2
Chengqun Qin, Yiyu Feng, Haoran An, Junkai Han, Chen Cao, Wei Feng
Multistimuli-responsive polymers are materials of emerging interest, but synthetically challenging. In this work, supramolecular assembly was employed as a facile and effective approach for constructing 3,3',5,5'-azobenzenetetracarboxylic acid (H4abtc)/poly(diallyldimethylammonium chloride) (PDAC) supramolecules. Structural transformations of H4abtc can be induced by light, mechanical force, and heat, and influenced by free volume. Thus, the fabricated freestanding H4abtc/PDAC film underwent bending/unbending movements upon treatment with light, humidity, or temperature, as asymmetric structural transformations on either side of the film generated asymmetric contraction/stretching forces...
January 12, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28079355/self-assembled-architectures-of-alkynylplatinum-ii-amphiphiles-and-their-structural-optimization-a-balance-of-the-interplay-among-pt%C3%A2-%C3%A2-%C3%A2-pt-%C3%AF-%C3%AF-stacking-and-hydrophobic-hydrophobic-interactions
#3
Heidi Li-Ki Fu, Charlotte Po, Sammual Yu-Lut Leung, Vivian Wing-Wah Yam
A series of alkynylplatinum(II) terpyridine complexes with triethylene glycol units was synthesized, and their self-assembly properties were investigated in solution by UV-vis absorption, emission, and (1)H NMR spectroscopy. The aggregation behaviors of several water-soluble complexes were investigated in aqueous media. Some of them were found to give rise to uniform fibers, suggesting the important role that triethylene glycol units has in regulating their self-assembly properties. Further modifications of these structures through the incorporation of alkyl chains and changes in counter-anions have rendered the complexes more amphiphilic in nature, and the effect of their alkyl chain lengths was studied and optimized...
January 12, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28079296/elasticity-in-macrophage-synthesized-biocrystals
#4
Elizabeth M Horstman, Rahul K Keswani, Benjamin A Frey, Phillip M Rzeczycki, Vernon LaLone, Jeffery A Bertke, Paul J A Kenis, Gus R Rosania
Supramolecular crystalline assembly constitutes a rational approach to bioengineer intracellular structures. Here, biocrystals of clofazimine (CFZ) that form in vivo within macrophages were measured to have marked curvature. Isolated crystals, however, showed reduced curvature suggesting that intracellular forces bend these drug crystals. Consistent with the ability of biocrystals to elastically deform, the inherent crystal structure of the principal molecular component of the biocrystals-the hydrochloride salt of CFZ (CFZ-HCl)-has a corrugated packing along the (001) face and weak dispersive bonding in multiple directions...
January 12, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28079225/bioconjugation-strategies-to-couple-supramolecular-exo-functionalized-palladium-cages-to-peptides-for-biomedical-applications
#5
J Han, A Schmidt, T Zhang, H Permentier, G M M Groothuis, R Bischoff, F E Kühn, P Horvatovich, A Casini
Supramolecular Pd2L4 cages (L = ligand) hold promise as drug delivery systems. With the idea of achieving targeted delivery of the metallacages to tumor cells, the bioconjugation of exo-functionalized self-assembled Pd2L4 cages to peptides following two different approaches is reported for the first time. The obtained bioconjugates were analyzed and identified by high-resolution mass spectrometry.
January 12, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28079195/a-ph-responsive-molecular-capsule-with-an-acridine-shell-catch-and-release-of-large-hydrophobic-compounds
#6
Mai Kishimoto, Kei Kondo, Munetaka Akita, Michito Yoshizawa
Unlike common polyaromatic hydrocarbons, acridine is a characteristic compound bearing both π-stackable large surfaces and a protonable nitrogen atom. Here we report the first synthesis of a supramolecular capsule with multiple acridine panels. In water, the assembly and disassembly of the capsule reversibly occur under neutral and acidic conditions, respectively (≥10 cycles). Notably, the pH-responsive capsule encapsulates a variety of large hydrophobic compounds (up to 1.6 nm in diameter) such as coumarins, metallophthalocyanines and subphthalocyanine in neutral water and subsequently releases them by simple addition of acid...
January 12, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28078752/two-new-copperoborates-with-mesoscale-cubic-supramolecular-cages-assembled-from-cu4-b20-clusters
#7
Guo-Yu Yang, Jia-Jia Wang, Qi Wei, Bai-Feng Yang
Two new copper borates with 3D supramolecular framework with mesoscale cavities have been made under solvothermal conditions, showing novel cubic supramolecular cages assembled by [(µ4-O)Cu4@B20O32(OH)8] ({Cu4@B20}) clusters with different point-group symmetry.
January 12, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28078725/chiral-amplification-by-self-assembly-of-neutral-luminescent-platinum-ii-complexes
#8
Alessandro Aliprandi, Christelle M Croisetu, Matteo Mauro, Luisa De Cola
Two novel enantiomerically pure chiral ligands and the corresponding neutral Pt(II) complexes have been synthetized and characterized. The self-assembly properties of the complexes have been investigated using different morphological and photophysical techniques. The two enantiomeric complexes, 4 a and 4 b, show high tendency to self-assemble into chiral supramolecular aggregates with right (P) and left-handed (M) helical configurations, respectively, as proven by SEM and absorption circular dichroism. The formation of such organized structures is driven by the formation of metallophilic and π-π interactions between spatially close Pt complexes with an enhancement of the chiro-optical properties in the solid state...
January 12, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28076948/cerium-iv-imido-complexes-structural-experimental-and-reactivity-studies
#9
Lukman A Solola, Alexander V Zabula, Walter L Dorfner, Brian C Manor, Patrick J Carroll, Eric J Schelter
A series of alkali metal capped cerium(IV) imido complexes, [M(solv)x][Ce=N(3,5-(CF3)2C6H3)(TriNOx)] (M = Li, K, Rb, Cs; solv = TMEDA, THF, Et2O or DME), was isolated and fully characterized. An X-ray structural investigation of the cerium imido complexes demonstrated the impact of the alkali metal counterions on the geometry of the [Ce=N(3,5-(CF3)2C6H3)(TriNOx)]- moiety. Substantial shortening of the Ce=N bond was observed with increasing size of the alkali metal cation. The first complex featuring an unsupported, terminal multiple bond between a Ce(IV) ion and a ligand fragment was also isolated by encapsulation of a Cs+ counterion with 2...
January 11, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28075570/contrasting-behavior-of-the-z-bonds-in-x-z%C3%A2-%C3%A2-%C3%A2-y-weak-interactions-z-main-group-elements-versus-the-transition-metals
#10
Jyothish Joy, Eluvathingal D Jemmis
In contrast to the increasing family of weak intermolecular interactions in main-group compounds (X-Z···Y, Z = main-group elements), an analysis of the Cambridge Structural Database indicates that electron-saturated (18-electron) transition-metal complexes show reluctance toward weak M bond formation (X-M···Y, M = transition metal). In particular, weak M bonds involving electron-saturated (18-electron) complexes of transition metals with partially filled d-orbitals are not found. We propose that the nature of valence electron density distribution in transition-metal complexes is the primary reason for this reluctance...
January 11, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28075559/one-component-supramolecular-filament-hydrogels-as-theranostic-label-free-magnetic-resonance-imaging-agents
#11
Lye Lin Lock, Yuguo Li, Xinpei Mao, Hanwei Chen, Verena Staedtke, Renyuan Bai, Wang Ma, Ran Lin, Yi Li, Guanshu Liu, Honggang Cui
Gadolinium (Gd)-based compounds and materials are the most commonly used magnetic resonance imaging (MRI) contrast agents in the clinic; however, safety concerns associated with their toxicities in the free ionic form have promoted the development of new generations of metal-free contrast agents. Here we report a supramolecular strategy to convert an FDA-approved anticancer drug, Pemetrexed (Pem), to a molecular hydrogelator with inherent chemical exchange saturation transfer (CEST) MRI signals. The rationally designed drug-peptide conjugate can spontaneously associate into filamentous assemblies under physiological conditions and consequently form theranostic supramolecular hydrogels for injectable delivery...
January 11, 2017: ACS Nano
https://www.readbyqxmd.com/read/28075551/cucurbit-n-uril-based-microcapsules-self-assembled-within-microfluidic-droplets-a-versatile-approach-for-supramolecular-architectures-and-materials
#12
Ji Liu, Yang Lan, Ziyi Yu, Cindy S Y Tan, Richard M Parker, Chris Abell, Oren A Scherman
Microencapsulation is a fundamental concept behind a wide range of daily applications ranging from paints, adhesives, and pesticides to targeted drug delivery, transport of vaccines, and self-healing concretes. The beauty of microfluidics to generate microcapsules arises from the capability of fabricating monodisperse and micrometer-scale droplets, which can lead to microcapsules/particles with fine-tuned control over size, shape, and hierarchical structure, as well as high reproducibility, efficient material usage, and high-throughput manipulation...
January 11, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28075548/triindole-tris-alkynyl-bridged-trinuclear-gold-i-complexes-for-cooperative-supramolecular-self-assembly-and-small-molecule-solution-processable-resistive-memories
#13
Eugene Yau-Hin Hong, Vivian Wing-Wah Yam
A novel class of luminescent trinuclear alkynylgold(I) complexes with N-alkyl substituted triindole ligands has been synthesized and characterized. They are found to exhibit rich photophysical and electrochemical properties. The complexes have been demonstrated to display interesting supramolecular assembly with spherical nanostructures in aqueous THF solution through a cooperative growth mechanism. The self-assembly process is shown to be mediated by the π-π stacking interactions and hydrophobic-hydrophobic interactions of the triindole moieties upon solvent modulation...
January 11, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28075509/complexation-and-electronic-communication-between-corannulene-based-buckybowls-and-a-curved-truxene-ttf-donor
#14
Maria Gallego, Joaquin Calbo, Rafael M Krick-Calderon, Paula Pla, Ya-Chu Hsieh, Emilio Manuel Pérez, Yao-Ting Wu, Enrique Orti, Dirk M Guldi, Nazario Martin
The association behavior of an electron-donating, bowl-shaped, truxene-based tetrathiafulvalene (truxTTF) with two corannulene-based fullerene fragments -C32H12 and C38H14- is investigated in several solvents. Formation of 1:1 complexes is followed by absorption titrations and complemented by density functional theory (DFT) calculations. The binding constants are in the range of log Ka 2.9-3.5. DFT calculations reveal that the conformation in which the 1,3-dithiole ring of truxTTF is placed inside the concave cavity of the corannulene derivative is the most stable arrangement...
January 11, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28074904/gd-iii-induced-supramolecular-hydrogelation-with-enhanced-magnetic-resonance-performance-for-enzyme-detection
#15
Yongquan Hua, Guojuan Pu, Caiwen Ou, Xiaoli Zhang, Ling Wang, Jiangtao Sun, Zhimou Yang, Minsheng Chen
Here we report a supramolecular hydrogel based on Gd(III)-peptide complexes with dramatically enhanced magnetic resonance (MR) performance. The hydrogelations were formed by adding Gd(III) ion to the nanofiber dispersion of self-assembling peptides naphthalene-Gly-Phe-Phe-Tyr-Gly-Arg-Gly-Asp (Nap-GFFYGRGD) or naphthalene-Gly-Phe-Phe-Tyr-Gly-Arg-Gly-Glu (Nap-GFFYGRGE). We further showed that, by adjusting the molar ratio between Gd(III) and the corresponding peptide, the mechanical property of resulting gels could be fine-tuned...
January 11, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28073248/interplay-of-g-protein-coupled-receptors-with-the-membrane-insights-from-supra-atomic-coarse-grain-molecular-dynamics-simulations
#16
Xavier Periole
G protein-coupled receptors (GPCRs) are central to many fundamental cellular signaling pathways. They transduce signals from the outside to the inside of cells in physiological processes ranging from vision to immune response. It is extremely challenging to look at them individually using conventional experimental techniques. Recently, a pseudo atomistic molecular model has emerged as a valuable tool to access information on GPCRs, more specifically on their interactions with their environment in their native cell membrane and the consequences on their supramolecular organization...
January 11, 2017: Chemical Reviews
https://www.readbyqxmd.com/read/28071051/supramolecular-platform-with-switchable-multivalent-affinity-photo-reversible-capture-and-release-of-bacteria
#17
Wenjun Zhan, Ting Wei, Limin Cao, Changming Hu, Yangcui Qu, Qian Yu, Hong Chen
Surfaces having dynamic control of interactions at the biological system-material interface are of great scientific and technological interest. In this work, a supramolecular platform with switchable multivalent affinity was developed to efficiently capture bacteria and on-demand release captured bacteria in response to irradiation with light of different wavelengths. The system consists of a photo-responsive self-assembled monolayer containing azobenzene (Azo) groups as guest and β-cyclodextrin (β-CD)-mannose (CD-M) conjugates as host, with each CD-M containing seven mannose units to display localized multivalent carbohydrates...
January 10, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28069889/thermodynamic-stabilities-of-three-way-junction-nanomotifs-in-prohead-rna
#18
Alyssa C Hill, Susan J Schroeder
The thermodynamic stabilities of four natural prohead or packaging RNA (pRNA) three-way junction (3WJ) nanomotifs and seven phi29 pRNA 3WJ deletion mutant nanomotifs were investigated using UV optical melting on a three-component RNA system. Our data reveal that some pRNA 3WJs are more stable than the phi29 pRNA 3WJ. The stability of the 3WJ contributes to the unique self-assembly properties of pRNA. Thus, ultrastable pRNA 3WJ motifs suggest new scaffolds for pRNA-based nanotechnology. We present data demonstrating that pRNA 3WJs differentially respond to the presence of metal ions...
January 9, 2017: RNA
https://www.readbyqxmd.com/read/28068101/supramolecular-big-bang-in-single-ionic-surfactant-water-system-driven-by-electrostatic-repulsions-from-vesicles-to-micelles
#19
Loïc Leclercq, Pierre Bauduin, Véronique Nardello-Rataj
In aqueous solution, dimethyl-di-n-octylammonium chloride, [DiC8][Cl], forms spontaneously dimers at low concentrations (1-10 mM) in order to decrease the hydrophobic/water contact. Dimers represent ideal building blocks for the abrupt edification of vesicles at 10 mM. These vesicles are fully characterized by dynamic and static light scattering, self-diffusion NMR and freeze-fracture transmission electron microscopy. An increase in concentration leads to electrostatic repulsions between vesicles which explode into small micelles at 30 mM...
January 9, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28068072/stacking-interactions-induced-selective-conformation-of-discrete-ar-omatic-arrays-and-borromean-rings
#20
Long Zhang, Lin Lin, Dong Liu, Yue-Jian Lin, Zhen-Hua Li, Guo-Xin Jin
Herein, we describe how to utilize stacking interactions to achieve selective supramolecular transfor-mation and molecular Borromean rings (BRs). By using a dinuclear NDI-based Cp*Rh acceptor and linear bipyridyl ligands, organometallic rectangles featuring dynamic behavior have been constructed. Unique discrete aromatic stack-ing arrays were formed by inducing pyrene units as guest molecules. The topology of the BRs was realized by the use of a strategically chosen ligand which was capable of participating in D-A interactions and hydrogen bonding, as evi-denced from single-crystal X-ray analysis and computational studies...
January 9, 2017: Journal of the American Chemical Society
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