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https://www.readbyqxmd.com/read/28644617/dynamic-covalent-chemistry-of-carbon-dioxide-opportunities-to-address-environmental-issues
#1
Jean Septavaux, Geoffroy Germain, Julien Leclaire
Extraction and purification of basic chemicals from complex mixtures has been a persistent issue throughout the development of the chemical sciences. The chemical industry and academic research have grown over the centuries by following a deconstruction-reconstruction approach, reminiscent of the metabolism process. Chemists have designed and optimized extraction, purification, and transformation processes of molecules from natural deposits (fossil fuels, biomass, ores), in order to reassemble them into complex adducts...
June 23, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28644555/a-self-assembled-trigonal-prismatic-molecular-vessel-for-catalytic-dehydration-reactions-in-water
#2
Partha Sarathi Mukherjee, Paramita Das, Atul Kumar, Prodip Howlader
A water-soluble Pd6 trigonal prism (A) was synthesized by two-component coordination-driven self-assembly of a Pd(II) 90° acceptor with a tetraimidazole donor. As the walls of the prism are constructed by three conjugated aromatic building blocks, the confined pocket of the prism is hydrophobic. In addition to the hydrophobic cavity, large product egress windows make A an ideal molecular vessel to catalyze otherwise challenging pseudo multicomponent dehydration reactions in its confined nanospace in aqueous medium...
June 23, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28644511/bacteriophage-tail-tube-assembly-studied-by-proton-detected-4d-solid-state-nmr
#3
Maximilian Zinke, Pascal Fricke, Camille Samson, Songhwan Hwang, Joseph Wall, Sascha Lange, Sophie Zinn-Justin, Adam Lange
Obtaining unambiguous resonance assignments remains a major bottleneck in solid-state NMR studies of protein structure and dynamics. Particularly for supramolecular assemblies with large subunits (>150 residues), the analysis of crowded spectral data presents a challenge, even if three-dimensional (3D) spectra are used. Here, we present a proton-detected 4D solid-state NMR assignment procedure that is tailored for large assemblies. The key to recording 4D spectra with three indirect carbon or nitrogen dimensions with their inherently large chemical shift dispersion lies in the use of sparse non-uniform sampling (as low as 2%)...
June 23, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28644469/cooperative-polymerization-of-%C3%AE-helices-induced-by-macromolecular-architecture
#4
Ryan Baumgartner, Hailin Fu, Ziyuan Song, Yao Lin, Jianjun Cheng
Catalysis observed in enzymatic processes and protein polymerizations often relies on the use of supramolecular interactions and the organization of functional elements in order to gain control over the spatial and temporal elements of fundamental cellular processes. Harnessing these cooperative interactions to catalyse reactions in synthetic systems, however, remains challenging due to the difficulty in creating structurally controlled macromolecules. Here, we report a polypeptide-based macromolecule with spatially organized α-helices that can catalyse its own formation...
July 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28643192/on-the-kinetics-of-body-versus-end-evaporation-and-addition-of-supramolecular-polymers
#5
Nitin S Tiwari, Paul van der Schoot
The kinetics of the self-assembly of supramolecular polymers is dictated by how monomers, dimers, trimers etc., attach to and detach from each other. It is for this reasons that researchers have proposed a plethora of pathways to explain the kinetics of various self-assembling supramolecules, including sulfur, linear micelles, living polymers and protein fibrils. Recent observations hint at the importance of a hitherto ignored molecular aggregation pathway that we refer to as "body evaporation and addition"...
June 2017: European Physical Journal. E, Soft Matter
https://www.readbyqxmd.com/read/28640997/from-1d-polymers-to-2d-polymers-preparation-of-free-standing-single-monomer-thick-two-dimensional-conjugated-polymers-in-water
#6
Na Zhang, Taisheng Wang, Xing Wu, Chen Jiang, Taiming Zhang, Bangkun Jin, Hengxing Ji, Wei Bai, Ruke Bai
Recently, investigation on two-dimensional (2D) organic polymers has been made a great progress and conjugated 2D polymers already play a dynamic role in both academic and practical applications. However, a convenient, non-interfacial approach to obtain single-layer 2D polymers in solution, especially in aqueous media remains challenging. Herein, we present a facile, highly efficient and versatile "1D to 2D" strategy for preparation of free-standing single-monomer-thick conjugated 2D polymers in water without any aid...
June 22, 2017: ACS Nano
https://www.readbyqxmd.com/read/28639791/insight-into-the-final-step-of-the-supramolecular-buildup-of-eumelanin
#7
Anne Büngeler, Benjamin Hämisch, Klaus Huber, Wolfgang Bremser, Oliver Ingolf Strube
The final step in the supramolecular buildup of eumelanin particles is investigated regarding involved species and mechanism. Time resolved in situ light scattering and scanning electron microscopy reveal an aggregation of particles with narrow size distribution around 40 nm, previously only observed as substructures. These form larger particles with again very uniform size and diameters around 200 nm. Aggregation of each single particle takes only a few minutes to complete, whereas the entire process goes on for at least three hours, partly due to kinetics of the precursors...
June 22, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28639790/programmable-assembly-of-peptide-amphiphile-via-noncovalent-to-covalent-bond-conversion
#8
Kohei Sato, Wei Ji, Liam C Palmer, Benjamin Weber, Matthias Barz, Samuel I Stupp
Controlling the number of monomers in a supramolecular polymer has been a great challenge in programmable self-assembly of organic molecules. One approach has been to make use of frustrated growth of the supramolecular assembly by tuning the balance of attractive and repulsive intermolecular forces. We report here on the use of covalent bond formation among monomers, compensating for intermolecular electrostatic repulsion, as a mechanism to control the length of a supramolecular nanofiber formed by self-assembly of peptide amphiphiles...
June 22, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28639403/writing-with-fluid-structuring-hydrogels-with-micrometer-precision-by-afm-in-combination-with-nanofluidics
#9
Nicolas Helfricht, Andreas Mark, Marina Behr, Andreas Bernet, Hans-Werner Schmidt, Georg Papastavrou
Hydrogels have many applications in biomedical surface modification and tissue engineering. However, the structuring of hydrogels after their formation represents still a major challenge, in particular due to their softness. Here, a novel approach is presented that is based on the combination of atomic force microscopy (AFM) and nanofluidics, also referred to as FluidFM technology. Its applicability is demonstrated for supramolecular hydrogel films that are prepared from low-molecular weight hydrogelators, such as derivates of 1,3,5-benzene tricarboxamides (BTAs)...
June 22, 2017: Small
https://www.readbyqxmd.com/read/28638095/mitochondria-localization-induced-self-assembly-of-peptide-amphiphiles-for-cellular-dysfunction
#10
M T Jeena, L Palanikumar, Eun Min Go, Inhye Kim, Myoung Gyun Kang, Seonik Lee, Sooham Park, Huyeon Choi, Chaekyu Kim, Seon-Mi Jin, Sung Chul Bae, Hyun Woo Rhee, Eunji Lee, Sang Kyu Kwak, Ja-Hyoung Ryu
Achieving spatiotemporal control of molecular self-assembly associated with actuation of biological functions inside living cells remains a challenge owing to the complexity of the cellular environments and the lack of characterization tools. We present, for the first time, the organelle-localized self-assembly of a peptide amphiphile as a powerful strategy for controlling cellular fate. A phenylalanine dipeptide (FF) with a mitochondria-targeting moiety, triphenyl phosphonium (Mito-FF), preferentially accumulates inside mitochondria and reaches the critical aggregation concentration to form a fibrous nanostructure, which is monitored by confocal laser scanning microscopy and transmission electron microscopy...
June 21, 2017: Nature Communications
https://www.readbyqxmd.com/read/28636358/transferable-atom-centered-potentials-for-the-correction-of-basis-set-incompleteness-errors-in-density-functional-theory
#11
Alberto Otero-de-la-Roza, Gino A DiLabio
Recent progress in the accurate calculation of non-covalent interactions has enabled density-functional theory (DFT) to model systems relevant in biological and supramolecular chemistry. The application of DFT methods using atom-centered Gaussian basis sets to large systems is limited by the number of basis functions required to accurately model thermochemistry and, in particular, weak intermolecular interactions. Basis-set incompleteness error (BSIE) arising from the use of incomplete basis sets leads to erroneous intermolecular energies, bond dissociation energies, and structures...
June 21, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/28636349/water-dynamics-from-the-surface-to-the-interior-of-a-supramolecular-nanostructure
#12
Julia H Ortony, Baofu Qiao, Christina J Newcomb, Timothy J Keller, Liam C Palmer, Elad Deiss-Yehiely, Monica Olvera de la Cruz, Songi Han, Samuel I Stupp
Water within and surrounding the structure of a biological system adopts context-specific dynamics that mediate virtually all of the events involved in the inner workings of a cell. These events range from protein folding and molecular recognition to the formation of hierarchical structures. Water dynamics are mediated by the chemistry and geometry of interfaces where water and biomolecules meet. Here we investigate experimentally and computationally the translational dynamics of vicinal water molecules within the volume of a supramolecular peptide nanofiber measuring 6...
June 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28636048/supramolecular-surface-functionalization-via-catechols-for-the-improvement-of-cell-material-interactions
#13
S Spaans, P P K H Fransen, B D Ippel, D F A de Bont, H M Keizer, N A M Bax, C V C Bouten, P Y W Dankers
Optimization of cell-material interactions is crucial for the success of synthetic biomaterials in guiding tissue regeneration. To do so, catechol chemistry is often used to introduce adhesiveness into biomaterials. Here, a supramolecular approach based on ureido-pyrimidinone (UPy) modified polymers is combined with catechol chemistry in order to achieve improved cellular adhesion onto supramolecular biomaterials. UPy-modified hydrophobic polymers with non-cell adhesive properties are developed that can be bioactivated via a modular approach using UPy-modified catechols...
June 21, 2017: Biomaterials Science
https://www.readbyqxmd.com/read/28636028/supramolecular-functional-assemblies-dynamic-membrane-transporters-and-peptide-nanotubular-composites
#14
Alberto Fuertes, Marisa Juanes, Juan R Granja, Javier Montenegro
The fabrication of functional molecular devices constitutes one of the most important current challenges for chemical sciences. The complex processes accomplished by living systems continuously demand the assistance of non-covalent interactions between molecular building blocks. Additionally, these building blocks (proteins, membranes, nucleotides) are also constituted by self-assembled structures. Therefore, supramolecular chemistry is the discipline required to understand the properties of the minimal self-assembled building blocks of living systems and to develop new functional smart materials...
June 21, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28634818/sg2na-is-a-regulator-of-endoplasmic-reticulum-er-homeostasis-as-its-depletion-leads-to-er-stress
#15
Buddhi Prakash Jain, Shweta Pandey, Nikhat Saleem, Goutam K Tanti, Shalini Mishra, Shyamal K Goswami
SG2NA belongs to a three-member striatin subfamily of WD40 repeat superfamily of proteins. It has multiple protein-protein interaction domains involved in assembling supramolecular signaling complexes. Earlier, we had demonstrated that there are at least five variants of SG2NA generated by alternative splicing, intron retention, and RNA editing. Such versatile and dynamic mode of regulation implicates it in tissue development. In order to shed light on its role in cell physiology, total proteome analysis was performed in NIH3T3 cells depleted of 78 kDa SG2NA, the only isoform expressing therein...
June 21, 2017: Cell Stress & Chaperones
https://www.readbyqxmd.com/read/28631930/fluorescent-and-electrochemical-supramolecular-coordination-polymer-hydrogels-formed-from-ion-tuned-self-assembly-of-small-bis-terpyridine-monomer
#16
Xudong Yu, Zengyao Wang, Yajuan Li, Lijun Geng, Jujie Ren, Guoliang Feng
Herein, ditopic ligand DTA comprised of terpyridine and acetylene segments with only one aromatic π-conjugated building block was designed and synthesized. Driven by metal-ligand coordination interactions, we presented that the use of metal salts can direct the self-assembly of DTA in the generation of fluorescent and electrochemical polymers that entrapped water to form ambidextrous hydrogels. These were characterized by several approaches including fluorescent titrations, UV-vis, circular dichroism, and X-ray diffraction spectra as well as scanning electron microscopy and transmission electron microscopy experiments...
June 20, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28631922/dual-property-supramolecular-h-bonded-15-crown-5-ln-iii-chains-joint-magneto-luminescence-and-ab-initio-studies
#17
Majeda Al Hareri, Zineb Ras Ali, Jeffery Regier, Emma L Gavey, Luis D Carlos, Rute A S Ferreira, Melanie Pilkington
Two complexes comprising 9-coordinate capped square antiprismatic [Ln(NO3)3(OH2)2(MeOH)] units [Ln(III) = Dy 6; Tb 7] are reported in which the metal complexes are hydrogen-bonded to 15C5 (15-crown-5) macrocycles to form supramolecular chains, {[Ln(NO3)3(OH2)2(MeOH)]·(15C5)}n. Alternating current magnetic susceptibility measurements supported by ab initio studies show field-induced SMM (single-molecule magnet) behavior for 6, but rapid relaxation of the magnetization for 7 because of the presence of dominant quantum tunneling processes as evidenced by the presence of a significant calculated tunnel splitting within the ground-state multiplet...
June 20, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28631892/water-mediated-structural-transformations-of-cu-ii-5-halonicotinates-coordination-networks-with-distinct-mechanisms
#18
Cheng-Peng Li, Hang Zhou, Yue Ju, Miao Du
Currently, no unequivocal evidence is given for elucidation of "black box" during the structural transformations of dynamic crystalline materials. Here, we have revealed three types of mechanisms for such transformations via X-ray diffraction and optical microscopy, namely, single-crystal to single-crystal (SC-SC) as well as "core-to-core" and "core-on-shell" processes. As confirmed by the time-lapse optical microscopy, the latter two cases can be properly ascribed as partial recrystallization processes, while the former one is a continuous process with two different crystal lattices simultaneously kept in one single crystal...
June 20, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28631865/chemical-communication-between-molecules
#19
REVIEW
Patricia Remón, Uwe Pischel
In this Minireview conceptual approaches towards the communication between (supra)molecular species are illustrated. The reviewed mechanisms include photophysical communication through energy transfer and communication mediated by chemical species that are released from precursors upon application of an external stimulus. The focus is on the stimulation by (reversible) photoreactions. Special attention has been given to supramolecular systems that illustrate the idea of chemical communication and information transfer in a very descriptive manner...
June 20, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28631856/tetrameric-and-dimeric-n%C3%A2-%C3%A2-%C3%A2-i-%C3%A2-%C3%A2-%C3%A2-n-halogen-bonded-supramolecular-cages
#20
Kari Rissanen, Lotta Turunen, Anssi Peuronen, Samu Forsblom, Elina Kalenius, Manu Lahtinen
Tripodal N-donor ligands are used to form halogen-bonded assemblies via structurally analogous Ag+-complexes. Selective formation of discrete tetrameric I6L4 and dimeric I3L2 halonium cages, wherein multiple [N∙∙∙I+∙∙∙N] halogen bonds are used in concert, can be achieved by using sterically rigidified cationic tris(1-methyl-1-azonia-4-azabicyclo[2.2.2]octane)-mesitylene ligand, L1(PF6)3, and flexible ligand 1,3,5-tris(imidazole-1-ylmethyl)-2,4,6-trimethylbenzene, L2, respectively. The iodonium cages, I6L14(PF6)18 and I3L22(PF6)3, were obtained through the [N∙∙∙Ag+∙∙∙N] → [N∙∙∙I+∙∙∙N] cation exchange reaction between the corresponding Ag6L14(PF6)18 and Ag3L22(PF6)3 coordination cages, prepared as intermediates, and I2...
June 20, 2017: Chemistry: a European Journal
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