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https://www.readbyqxmd.com/read/28430448/structural-and-rheological-properties-of-temperature-responsive-amphiphilic-triblock-copolymers-in-aqueous-media
#1
Josefine Eilsø Nielsen, Kaizheng Zhu, Sverre Arne Sande, Lubomír Kováčik, Dušan Cmarko, Kenneth Dahl Knudsen, Bo Nyström
Thermoresponsive amphiphilic biodegradable block copolymers of the type poly(-caprolactone-co-lactide)-poly(ethylene glycol)-poly(-caprolactone-co-lactide) (PCLA-PEGm-PCLA) have great potential for various biomedical applications. In the present study, we have surveyed the effects of PEG-spacer length (m=1000 and 1500), temperature, and polymer concentration on the self-assembling process to form supramolecular structures in aqueous solutions of the PCLA-PEGm-PCLA copolymer. This copolymer has a lower critical solution temperature, and the cloud point depends on both concentration and PEG-length...
April 21, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28430417/charge-separation-mechanisms-in-ordered-films-of-self-assembled-donor-acceptor-dyad-ribbons
#2
Jenna L Logsdon, Patrick E Hartnett, Jordan N Nelson, Michelle A Harris, Tobin J Marks, Michael R Wasielewski
Orthogonal attachment of polar and nonpolar side-chains to a zinc porphyrin-perylenediimide dyad (ZnP-PDI, 1a) is shown to result in self-assembly of ordered supramolecular ribbons in which the ZnP and PDI molecules form segregated π-stacked columns. Following photoexcitation of the ordered ribbons, ZnP(+•)-PDI(-•) radical ion pairs form in <200 fs and subsequently produce a 30 ± 3% yield of free charge carriers that live for about 100 μs. Elongating the side chains on ZnP and PDI in 1b enhances the order of the films, but does not result in an increase in free charge carrier yield...
April 21, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28430270/atomistic-non-adiabatic-dynamics-of-the-lh2-complex-with-a-gpu-accelerated-ab-initio-exciton-model
#3
Aaron Sisto, Clem Stross, Marc W van der Kamp, Michael O'Connor, Simon McIntosh-Smith, Graham T Johnson, Edward G Hohenstein, Fred R Manby, David R Glowacki, Todd J Martinez
We recently outlined an efficient multi-tiered parallel ab initio excitonic framework that utilizes time dependent density functional theory (TDDFT) to calculate ground and excited state energies and gradients of large supramolecular complexes in atomistic detail - enabling us to undertake non-adiabatic simulations which explicitly account for the coupled anharmonic vibrational motion of all the constituent atoms in a supramolecular system. Here we apply that framework to the 27 coupled bacterio-chlorophyll-a chromophores which make up the LH2 complex, using it to compute an on-the-fly nonadiabatic surface-hopping (SH) trajectory of electronically excited LH2...
April 21, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28430199/control-over-differentiation-of-a-metastable-supramolecular-assembly-in-one-and-two-dimensions
#4
Tomoya Fukui, Shinnosuke Kawai, Satoko Fujinuma, Yoshitaka Matsushita, Takeshi Yasuda, Tsuneaki Sakurai, Shu Seki, Masayuki Takeuchi, Kazunori Sugiyasu
Molecular self-assembly under kinetic control is expected to yield nanostructures that are inaccessible through the spontaneous thermodynamic process. Moreover, time-dependent evolution, which is reminiscent of biomolecular systems, may occur under such out-of-equilibrium conditions, allowing the synthesis of supramolecular assemblies with enhanced complexities. Here we report on the capacity of a metastable porphyrin supramolecular assembly to differentiate into nanofibre and nanosheet structures. Mechanistic studies of the relationship between the molecular design and pathway complexity in the self-assembly unveiled the energy landscape that governs the unique kinetic behaviour...
May 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28430193/self-propelled-supramolecular-nanomotors-with-temperature-responsive-speed-regulation
#5
Yingfeng Tu, Fei Peng, Xiaofeng Sui, Yongjun Men, Paul B White, Jan C M van Hest, Daniela A Wilson
Self-propelled catalytic micro- and nanomotors have been the subject of intense study over the past few years, but it remains a continuing challenge to build in an effective speed-regulation mechanism. Movement of these motors is generally fully dependent on the concentration of accessible fuel, with propulsive movement only ceasing when the fuel consumption is complete. Here we report a demonstration of control over the movement of self-assembled stomatocyte nanomotors via a molecularly built, stimulus-responsive regulatory mechanism...
May 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28429811/synthesis-and-structural-characterisation-of-the-aggregates-of-benzo-1-2-chalcogenazole-2-oxides
#6
Peter C Ho, Jamal Rafique, Jiwon Lee, Lucia M Lee, Hilary A Jenkins, James F Britten, Antonio L Braga, Ignacio Vargas-Baca
Iodine oxidation of bis[2-(hydroxyiminomethyl)phenyl] dichalcogenides yields benzo-1,2-chalcogenazole 2-oxides. Annulated derivatives of iso-tellurazole N-oxides spontaneously aggregate into cyclic tetra- and hexamers through TeO chalcogen bonding; the structures of the co-crystals with benzene and CH2Cl2 illustrate the ability of these macrocycles to interact with small guest molecules. The selenium congener crystallizes forming a supramolecular polymer. VT NMR indicates that both compounds aggregate in solution but only at low temperature in the selenium case...
April 21, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28429494/a-modular-approach-to-inorganic-phosphazane-macrocycles
#7
Alex J Plajer, Raúl García-Rodríguez, Callum G M Benson, Peter D Matthews, Andrew D Bond, Sanjay Singh, Lutz H Gade, Dominic S Wright
Inorganic macrocycles, based on non-carbon backbones, present exciting synthetic challenges in the systematic assembly of inorganic molecules, as well as new avenues in host-guest and supramolecular chemistry. Here we demonstrate a new high-yielding modular approach to a broad range of trimeric and hexameric S- and Se-bridged inorganic macrocycles based on cyclophosphazane frameworks, using the building blocks [S=(H)P(μ-NR)]2 . The method involves the in situ generation of the key intermediate [E....._ (S...
April 21, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28429421/a-boat-shaped-tetracationic-macrocycle-with-a-semiconducting-organic-framework
#8
Minh T Nguyen, Matthew D Krzyaniak, Magdalena Owczarek, Daniel P Ferris, Michael R Wasielewski, J Fraser Stoddart
We report the synthesis of a tetracationic macrocycle which contains two N,N'-bis(methylene)naphthalenediimide units inserted in between the pyridinium rings of the bipyridinium units in cyclobis(paraquat-p-phenylene) (CBPQT(4+) or "blue box") and describe the investigation of its potential use in materials for organic electronics. The incorporation of the two naphthalenediimide (NDI) units into the constitution of CBPQT(4+) , not only changes the supramolecular properties of the tetracation in the solid state, but also has a profound influence on the electrochemical and electronic behavior of the resulting tetracationic macrocycle...
April 21, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28428986/ruthenium-cobalt-dinuclear-complexes-as-photocatalysts-for-co2-reduction
#9
X Wang, V Goudy, G Genesio, J Maynadié, D Meyer, M Fontecave
A series of Ru-Co dinuclear complexes have been synthesized and assayed as photocatalysts for the reduction of CO2 to CO in organic solvents. The Ru-Co complexes, with tris-diimine coordination at the Co ion, are the best supramolecular photocatalysts for CO2 reduction with a non-noble metal catalytic center reported so far.
April 21, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28427653/thermolysis-synthesis-of-pure-phase-nio-from-novel-sonochemical-synthesized-ni-ii-nano-metal-organic-supramolecular-architecture
#10
Younes Hanifehpour, Ali Morsali, Babak Mirtamizdoust, Sang Woo Joo, Behzad Soltani
Nano-structures of a new supramolecular coordination compound of divalent nickel with the pyrazol (pzH) containing the terminal azide anions, [Ni(pzH)2(N3)2] (1), with discrete molecular architecture (DMA) in solid state was synthesized via sonochemical method. The new nanostructure was characterized by scanning electron microscopy, X-ray powder diffraction, IR, and elemental analysis. Compound 1 was structurally characterized by single crystal X-ray diffraction and the single-crystal X-ray data shows that the coordination number of Ni (II) ions is six, (NiN6), with four N-donor atoms from neutral "pzH" ligands and two N-donors from two terminal azide anions...
July 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28427651/ultrasonic-synthesis-of-two-nanostructured-cadmium-ii-coordination-supramolecular-polymers-solvent-influence-luminescence-and-photocatalytic-properties
#11
Shao Yun Hao, Xue Gang Ma, Guang Hua Cui
Two nanoparticles of cadmium(II) coordination polymers (CPs) formulated as [Cd(L)(DCTP)]n (1) and [Cd(L)2(DCTP)·2H2O]n (2) (L=1,2-bis(2-methylbenzimidazol-1-ylmethyl)benzene, H2DCTP=2,5-dichloroterephthalic acid) were prepared by the sonochemical approach in different solvents and characterized by elemental analysis, IR spectra, scanning electron microscopy (SEM), and powder X-ray diffraction. Structural determination reveals that CP 1 displays a 2D four-connected sql net layer, Whilst CP 2 exhibits a 1D "V"-like chain structure...
July 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28427648/sonochemical-synthesis-characterization-and-effects-of-temperature-power-ultrasound-and-reaction-time-on-the-morphological-properties-of-two-new-nanostructured-mercury-ii-coordination-supramolecule-compounds
#12
Payam Hayati, Ali Reza Rezvani, Ali Morsali, Daniel Ruiz Molina, Samira Geravand, Salvio Suarez-Garcia, Miguel Angel Moreno Villaecija, S García-Granda, Rafael Mendoza-Meroño, Pascal Retailleau
Two new mercury(II) coordination supramolecular compounds (CSCs) (1D and 0D), [Hg(L)(I)2]n (1) and [Hg2(L')2(SCN)2]·2H2O (2) (L=2-amino-4-methylpyridine and L'=2,6-pyridinedicarboxlic acid), have been synthesized under different experimental conditions. Micrometric crystals (bulk) or nano-sized materials have been obtained depending on using the branch tube method or sonochemical irradiation. All materials have been characterized by field emission scanning electron microscope (FESEM), scanning electron microscopy (SEM), powder X-ray diffraction (PXRD) and FT-IR spectroscopy...
July 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28427635/sonochemical-synthesis-of-two-new-zinc-ii-1-10-phenanthroline-coordination-supramolecular-compounds-new-precursors-to-produce-nano-sized-zinc-ii-oxide
#13
Mohammad Jaafar Soltanian Fard, Payam Hayati, Azita Firoozadeh, Jan Janczak
Nanoparticles of two zinc(II) coordination supramolecule compounds (CSCs), [Zn(L)Cl2] (1) and [Zn(L)Br2] (2) L=1,10-phen=1,10-phenanthroline ligand, have been synthesized by use of a sonochemical process and characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRPD), Fourier transform infrared (FTIR) spectroscopy and elemental analyses. The single crystal X-ray data of compounds 1 and 2 imply that the Zn(+2) ions are four coordinated. Topological analysis shows that the compound 1 and 2 are new topology for net: 1,3M4-1...
July 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28427014/chemical-and-biological-properties-of-a-supramolecular-complex-of-tuftsin-and-cucurbit-7-uril
#14
Ekaterina A Kovalenko, Ekaterina A Pashkina, Lyubov Y Kanazhevskaya, Alexey N Masliy, Vladimir A Kozlov
Cucurbit[7]uril (CB7) is an uncharged and water-soluble macrocyclic host. CB7 binds to doubly protonated tuftsin, which is the tetrapeptide Thr-Lys-Pro-Arg, with moderate affinity (Ka=2.1×10(3)M(-1)). In this study, the host-guest complexation was confirmed by fluorescence titration. This affinity would allow for easy release of the peptide under physiological conditions. According to density functional theory calculations, the structural binding motif involves hydrogen bonding. The most energetically stable form had the Arg side chain inside the CB7 cavity...
April 17, 2017: International Immunopharmacology
https://www.readbyqxmd.com/read/28426933/triggering-assembly-and-disassembly-of-a-supramolecular-cage
#15
Carlo Bravin, Elena Badetti, Francesca Anna Scaramuzzo, Giulia Licini, Cristiano Zonta
A novel supramolecular cage built from the self-assembly of tris(2-pyridylmethyl)amine TPMA zinc complexes through imine condensation chemistry is reported. The cage recognition properties over a variety of structurally related guests, together with the kinetic study of the template assembly and disassembly, have been investigated in detail. This knowledge has been used to selectively modulate the rate of both assembly and disassembly processes. In particular, a novel disassembly method induced by strain release of the guest has been developed...
April 20, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28426220/fluorescent-neuraminidase-assay-based-on-supramolecular-dye-capture-after-enzymatic-cleavage
#16
Wenqi Liu, César F A Gómez-Durán, Bradley D Smith
A conceptually new type of enzymatic cleavage assay is reported that utilizes in-situ supramolecular capture of the fluorescent product. A squaraine-derived substrate with large blocking groups at each end of its structure cannot be threaded by a tetralactam macrocycle until the blocking groups are removed by enzyme cleavage. A prototype design responds to viral neuraminidase, an indicator of influenza infection, and also measures susceptibility of the sample to neuraminidase inhibitor drugs. The substrate structure incorporates three key features; (a) a bis(4-amino-3-hydroxyphenyl)squaraine core with bright deep-red fluorescence and excellent photostability, (b) an N-methyl group at each end of the squaraine core that ensures fast macrocycle threading kinetics, and (c) sialic acid blocking groups that prevent macrocycle threading until they are removed by viral neuraminidase...
April 20, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28426196/chiral-inorganic-nanostructures
#17
Wei Ma, Liguang Xu, André F de Moura, Xiaoling Wu, Hua Kuang, Chuanlai Xu, Nicholas A Kotov
The field of chiral inorganic nanostructures is rapidly expanding. It started from the observation of strong circular dichroism during the synthesis of simple nanoparticles (NPs) and their assemblies mediated by biomolecules and expanded to sophisticated synthetic protocols involving nanostructures from metals, semiconductors, ceramics, and nanocarbons. Besides the well-established chirality transfer from bioorganic molecules, other methods to impart handedness to nanoscale matter specific to inorganic materials were discovered, including three-dimentional lithography, multiphoton chirality transfer, polarization effects in nanoscale assemblies, and others...
April 20, 2017: Chemical Reviews
https://www.readbyqxmd.com/read/28426072/in-situ-hybridization-of-coox-nanoparticles-on-n-doped-graphene-through-one-step-mineralization-of-co-responsive-hydrogels
#18
Jing Ma, Xiaojuan Wang, Ting He, Minli Tan, Jun Zheng, Huiqiong Wu, Mengying Yuan, Rujuan Shen, Yi Zhang, Juan Xiang
The in situ hydrothermal mineralization for a mixture of graphene oxide (GO) and Co-responsive supramolecular hydrogels led to a hybrid graphene aerogel, doped with Co and N elements. The as-prepared aerogels exhibited a competitive half-wave potential (0.840 V, versus RHE) and peak current density (2.35 mA cm(-2)) to that of Pt/C (0.836 V, 2.23 mA cm(-2), respectively). Furthermore, they demonstrated a significantly perfect catalytic efficiency (nearly 100% of 4e(-) ORR) toward the oxygen reduction reaction (ORR)...
April 20, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28425835/enzymatic-synthesis-and-protein-adsorption-properties-of-crystalline-nanoribbons-composed-of-cellulose-oligomer-derivatives-with-primary-amino-groups
#19
Takatoshi Nohara, Toshiki Sawada, Hiroshi Tanaka, Takeshi Serizawa
The in vitro enzymatic synthesis of cellulose and its derivatives has attracted growing interest for fabricating novel cellulose-based supramolecular assemblies with unique physicochemical and functional properties. However, their potential biomedical applications have not been sufficiently demonstrated despite their useful features of designable structures and tailor-made surface functionalities. Herein, we demonstrated the production of crystalline nanoribbons composed of cellulose oligomer derivatives with primary amino groups via cellodextrin phosphorylase-catalyzed single-step reactions using α-D-glucose l-phosphate monomers and 2-aminoethyl-β-D-glucoside primers...
April 20, 2017: Journal of Biomaterials Science. Polymer Edition
https://www.readbyqxmd.com/read/28425524/excited-state-relaxation-processes-of-h2-evolving-ru-pd-supramolecular-photocatalysts-containing-a-linear-or-non-linear-bridge-a-dft-and-tddft-study
#20
Jun Cao, Yun Zhou
In this study, the early-time excited state relaxation processes of bimetallic Ru-Pd supramolecular photocatalysts containing a linear 2,2':5',2''-terpyridine or a nonlinear 2,2':6',2''-terpyridine bridging ligand (BL) were investigated by density functional theory (DFT) and time-dependent DFT (TDDFT) approaches. The bridge based metal-to-ligand charge transfer triplet ((3)MLCT) state of the metal complex containing a linear bridging ligand was calculated to be the lowest energy triplet (T1) state which is closely related to the photocatalytic H2 production, while for that having a nonlinear bridging ligand, the T1 state is a Ru metal-centered (MC) triplet ((3)MCRu) state that is short-lived and rapidly decays to the ground electronic state (S0)...
April 20, 2017: Physical Chemistry Chemical Physics: PCCP
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