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Chemistry: a European Journal

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https://www.readbyqxmd.com/read/30243031/designing-dnazyme-powered-nanomachines-simultaneously-responsive-to-multiple-micrornas
#1
Xiaoxi Zhong, Sishu Yang, Peng Yang, Huan Du, Xiandeng Hou, Junbo Chen, Rongxing Zhou
Herein, we designed a DNAzyme-powered nanomachine responsive to multiple hepatocellular carcinoma (HCC) related miRNAs derived from clinical samples. Initially, three types of nanomachines were constructed with dye molecules (FAM, TMR and Cy5) labeled DNA-RNA chimeric substrate and specific recognized probe for corresponding miRNAs target. Once the target miRNAs was captured by two recognized probes, the DNA nanomachine was initiated, leading to the hybridization between DNAzyme and substrates. With the help of cofactor, the automatic operation of nanomachine was driven by cyclic cleavage of DNAzyme...
September 22, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/30242926/functional-conjugated-polymers-for-co2-reduction-using-visible-light
#2
Can Yang, Wei Huang, Lucas Caire da Silva, Kai A I Zhang, Xinchen Wang
The reduction of CO2 with visible light is a highly sustainable method for producing valuable chemicals. The function-led design of organic conjugated semiconductors with more chemical variety than that of inorganic semiconductors has emerged as a method for achieving carbon photofixation chemistry. Here, we report the molecular engineering of triazine-based conjugated microporous polymers to capture, activate and reduce CO2 to CO with visible light. The optical band gap of the CMPs is engineered by varying the organic electron-withdrawing (benzothiadiazole) and electron-donating units (thiophene) on the skeleton of the triazine rings while creating organic Donor-Acceptor junctions to promote the charge separation...
September 22, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/30242922/the-role-of-n-methyl-squaramides-in-a-hydrogen-bonding-strategy-to-fold-peptidomimetic-compounds
#3
Carmen Rotger, Luís Martínez-Crespo, Eduardo C Escudero-Adán, Antonio Costa
Small peptides and peptomimetic compounds are valuable tools to probe and study biological systems. Small synthetic peptide analogs adopt a given secondary structure driven by structural modules that organize the compound architecture. Among them, β-and α-turn mimetics are widely used. We have developed SQ4 and SQ5 squaramido-based turn modules that combine tertiary and secondary squaramide bonds in their structure to control their conformational properties. We have evaluated the efficacy of this combination to promote folding in peptide-like compounds to obtain parallel and antiparallel-hairpin model compounds in hydrogen bonding competitive media...
September 22, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/30242911/photoswitchable-self-assembly-disassembly-of-near-infrared-fluorophores
#4
Ming-Qiang Zhu, Nuo-Hua Xie, Chong Li, Ying Chen, Tao Chen, Zhitian Liu
A novel photoswitchable near-infrared fluorophore with symmetric structure exhibits reversible photo-controllable self-assembly and disassembly. The modification of π-conjugated terrylenediimide with four dithienylethene groups not only realizes photoswitchable near-infrared fluorescence, but also photo-regulated reversible precipitation-dissolution with microscopic and macroscopic polymorphism. Upon 302-nm UV irradiation, the noticeable precipitation has been observed in seconds, which is gradually dissolved again in half an hour upon visible light irradiation...
September 22, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/30242924/interfacial-asymmetric-post-functionalization-of-graphene-amphiphilic-graphene-derivatives-self-assembled-to-3d-superstructures
#5
Vasilios Georgakilas, Sofia Georgitsopoulou, Angelliki Karakassides
We present here the interfacial asymmetric post functionalization of graphene nanosheets and their self assembling into superstructures. Performing two sequential functionalizations, graphene nanosheets lying in the interface of a biphasic aqueous-organic system become amphiphilic, obtaining an organophilic and a hydrophilic side. The as prepared Janus type amphiphilic graphene nanosheets are then self assembled to different interesting superstructures, depending on the solvent that are dispersed.
September 21, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/30240074/s%C3%A2-%C3%A2-%C3%A2-sn-tetrel-bonds-are-involved-in-the-activation-of-peroxisome-proliferator-activated-receptors-ppars-by-organotin-molecules
#6
Antonio Frontera, Antonio Bauzá
In this study we have combined a PDB (Protein DataBank) analysis backed up with theoretical calculations (PBE0-D3/def2-TZVP level of theory) to analyze the impact of S···Sn tetrel bonding interactions in the activation mechanism of peroxisome proliferator-activated receptors (PPARs) by two organotin derivatives, triphenyltin (TPT) and tributyltin (TBT). Our findings indicate that the presence of a covalently bonded CYS285 to the organotin molecule is key to enhance the σ-hole donor ability of the tin atom, thus strengthening the tetrel bonding interaction with a S atom belonging to a vicinal methionine residue (MET364)...
September 21, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/30240067/quantitative-binding-behavior-of-intrinsically-disordered-proteins-to-nanoparticle-surfaces-at-individual-residue-level
#7
Mouzhe Xie, Dawei Li, Jiaqi Yuan, Alexandar Hansen, Rafael Bruschweiler
The quantitative and predictive understanding how intrinsically disordered proteins (IDPs) interact with engineered nanoparticles has potentially important implications for new therapeutics as well as nanotoxicology. Based on a recently developed solution 15N NMR relaxation approach, the interactions between four representative IDPs with silica nanoparticles are reported at atomic detail. Each IDP possesses distinct binding modes, which can be quantitatively explained by the local amino-acid residue composition using a "free residue interaction model" that was parameterized using the binding affinities of free proteinogenic amino acids along with long-range effects, derived by site-specific mutagenesis, that exponentially scale with distance along the primary sequence...
September 21, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/30240046/trifluoromethanesulfinyl-chloride-for-electrophilic-trifluoromethythiolation-and-bifunctional-chlorotrifluoromethythiolation
#8
Lvqi Jiang, Qiang Yan, Rongkang Wang, Tianqi Ding, Webin Yi, Wei Zhang
Trifluoromethanesulfinyl chloride (CF3SOCl) is introduced as a new reagent for C-H trifluoromethylthiolation of indoles, thiophenes, and ketones under catalyst-free conditions and in the absence of reductant. The disproportionation of CF3SOCl to CF3SO2Cl and CF3SCl provides two pathways for the trifluoromethylthiolation. Direct trifluoromethylthiolation with CF3SCl or trifluoromethylsulfoxidation with CF3SOCl followed by the reduction with CF3SOCl. This reagent can be used to functionalize benzothiophenes, benzofurans and indenes under the catalysis of Ag2CO3...
September 21, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/30239060/preparation-of-siloxane-based-microporous-crystal-from-hydrogen-bonded-molecular-crystal-of-cage-siloxane
#9
Naoto Sato, Yoshiyuki Kuroda, Hiroaki Wada, Atsushi Shimojima, Kazuyuki Kuroda
Controlled assembly of siloxane-based building blocks provides a rational approach toward designed architectures of silica-based porous materials. Here we report a non-hydrothermal method to prepare microporous crystals from cage-type oligosiloxanes via ordered assembly assisted by hydrogen bonds and subsequent intermolecular connection by silylation. Cage siloxanes with a double-four membered ring (D4R) structure were modified with dimethylsilanol groups. Intermolecular hydrogen bonding of the dimethylsilanol groups led to the formation of a pillared layer structure consisting of the D4R units...
September 21, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/30239042/closing-the-loop-triazolylpyridine-coordination-drives-the-self-assembly-of-metallomacrocycles-with-tunable-topologies-for-small-molecule-and-guanine-quadruplex-recognition
#10
Anne Petitjean, Caitlin E Miron, Madelaine R Colden Leung, Emily I Kennedy, Nan Wu, Olivier Fleischel, Jean-Louis Mergny, Mona Ashraf Khorasani
The 2-(1,2,3-triazol-4-yl)pyridine motif, with its facile "Click" synthesis and remarkable coordinative properties, is an attractive chelate for applications in the metal-directed self-assembly of intricate three dimensional structures. Organic ligands bearing two such chelates bridged by flexible hinge moieties readily undergo self-assembly with metal ions of different coordination geometries to generate a series of topologically diverse metallomacrocycles which can be used for numerous applications...
September 21, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/30238528/an-electron-rich-calix-4-arene-based-receptor-with-unprecedented-binding-affinity-for-nitric-oxide
#11
Denan Wang, Lena V Ivanova, Maxim Ivanov, Saber Mirzaei, Qadir Timerghazin, Scott Reid, Rajendra Rathore
Calixarenes have found widespread application as building blocks for the design and synthesis of functional materials in host-guest chemistry. The ongoing desire to develop a detailed understanding of the nature of NO bonding to multichromophoric π-stacked assemblies led us to develop an electron-rich methoxy derivative of calix[4]arene, which we show exists as a single conformer in solution at ambient temperature. Here we examine the redox properties of this derivative, generate its cation radical using robust chemical oxidants, and determine the relative efficacy of its NO binding in comparison with model calixarenes...
September 21, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/30238642/beyond-common-metal-metal-bonds-%C3%AE%C2%BA3-bis-donor-ferrocenyl%C3%A2-transition-metal-interaction
#12
Mark Ringenberg
Ligands with 1,1'-bis(donor)ferrocene motif are capable of a wide range of binding modes, including the trans chelation mode in which there is a Fe-M interaction (κ3-D,Fe-D), in the form of a dative Fe→TM bond (TM = transition metal). This minireview will explore the nature of this Fe-TM interaction thorough select examples as well as how to characterize a Fe→TM dative bond using physical, computational, and spectroscopic techniques.
September 20, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/30238538/inspecting-the-electronic-architecture-and-semiconducting-properties-of-a-rosette-like-supramolecular-columnar-liquid-crystal
#13
Beatriz Feringán, César L Folcia, Roberto Termine, Attilio Golemme, José M Granadino-Roldán, Amparo Navarro, José Luis Serrano, Raquel Giménez, Teresa Sierra
Computational and experimental studies unravel the structural and electronic properties of a novel supramolecular liquid crystal built through a hierarchical assembly process resulting in an H-bonded melamine rosette decorated with peripheral triphenylenes. The six-fold symmetry of the mesogen facilitates the formation of a highly organized hexagonal columnar mesophase stable at room temperature. X-ray diffraction and electron density maps confirm additional intra- and intercolumn segregation of functional subunits, and this paves the way for 1D charge transport...
September 20, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/30238526/corannulenes-with-electron-withdrawing-substituents-synthetic-approaches-and-resulting-structural-and-electronic-properties
#14
Axel Haupt, Dieter Lentz
Corannulene is a multifaceted polyaromatic compound. It has many interesting properties, for example a bowl-shaped molecular structure which in addition undergoes a dynamic inversion process. It gained a lot of attraction within the last decades. This is not only due to its structural, but also its electronic properties and finally its various potential applications in materials chemistry. Herein, we summarize on the synthetic approaches towards corannulene derivatives with electron-withdrawing substituents...
September 20, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/30238524/structural-effect-of-fusicoccin-upon-upregulation-of-14-3-3-phospholigand-interaction-and-cytotoxic-activity
#15
Junko Ohkanda, Atsushi Kusumoto, Louvy Punzalan, Ryoma Masuda, Chenyu Wang, Prakash Parvatkar, Dai Akase, Misako Aida, Motonari Uesugi, Yusuke Higuchi, Nobuo Kato
Fusicoccins (FCs) exhibit various cellular activities in mammalian cells, but details of the mechanism of action are not fully understood. In this study, we synthesized two pairs of model derivatives of FCs differing only in the presence and absence of a 12-hydroxyl group and evaluated binding to a 14-3-3 protein together with various mode 1 and mode 3 phosphopeptide ligands. Our results demonstrate that the 12-hydroxyl group hampers binding to 14-3-3 with mode 1 phospholigands, presumably due to steric repulsion with the i+2 residue...
September 20, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/30238521/the-visible-light-challenge-in-contemporary-photochemistry
#16
Janin T Offenloch, Marvin Gernhard, James P Blinco, Hendrik Frisch, Hatice Mutlu, Christopher Barner-Kowollik
Catalyst-free and bond forming light induced reactions have seen an unprecedented renaissance in the realm of soft matter materials science due to their efficiency, spatio-temporal controllability and, sometimes, photoreversible nature. However, many of these reactions rely on the application of high energy UV light that can cause photo-degradation and is inapplicable in biological environments. If up-conversion systems or two photon processes are to be avoided, strategies for red-shifting catalyst-free ligation technology are critically required...
September 20, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/30238520/synthesis-strategies-and-structural-arrangements-of-isoreticular-mixed-component-metal-organic-frameworks
#17
Johannes Bitzer, Wolfgang Kleist
In recent years, the synthesis of mixed-metal and mixed-linker metal-organic frameworks with multiple metals and/or linker molecules combined in one framework has become a growing field of interest. These mixed-component or multivariate metal-organic framework materials provide the possibility to introduce multiple functionalities inside one framework. The interaction of guest molecules with different functionalities in the same material is a promising approach in the fields of gas storage, separation, catalysis and drug delivery...
September 20, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/30238511/gold-decoration-and-photoresistive-response-to-nitrogen-dioxide-of-ws2-nanotubes
#18
Alexander Polyakov, Daniil A Kozlov, Vasily A Lebedev, Ratibor A Chumakov, Alexander S Frolov, Lada V Yashina, Marina N Rumyantseva, Eugene A Goodilin
Composites of WS2 nanotubes (NT-WS2) and gold nanoparticles (AuNPs) were prepared using HAuCl4 aqueous solutions and subjected to the surface analysis. The obtained materials were jointly characterized by X-ray photoelectron (XPS), Raman scattering (RSS), ultraviolet photoelectron (UPS) spectroscopies. Optical extinction spectroscopy and electron energy loss spectroscopy in scanning electron microscopy regime (STEM-EELS) were also employed to study plasmon features of the nanocomposite. We found that AuNPs deposition is accompanied by a partial oxidative dissolution of WS2, while Au-S interfacial species could be responsible for the tight contact of metal nanoparticles and the disulfide...
September 20, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/30231192/multipurpose-energetic-materials-by-shuffling-nitro-groups-on-a-3-3-bipyrazole-moiety
#19
Jean'ne M Shreeve, Dheeraj Kumar, Yongxing Tang, Chunlin He, Gregory H Imler, Damon Parrish
A family of 3,3'-bipyrazole-based energetic compounds having C-NO2/N-NO2 functionalities was synthesized by using various nitrating conditions. Depending on the number and nature of energetic nitro groups (C-NO2/N-NO2), different classes of energetic materials, such as green primary explosives, high-performance secondary explosives and heat-resistant explosives, were obtained. All the compounds were thoroughly characterized by IR, NMR [1H, 13C{1H}, 15N], elemental analysis, and differential scanning calorimetry (DSC)...
September 19, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/30230657/ruthenium-complexes-bearing-thiophene-based-unsymmetrical-n-heterocyclic-carbene-ligands-as-selective-catalysts-for-olefin-metathesis-in-toluene-and-environmentally-friendly-2-methyltetrahydrofuran
#20
Michał Smoleń, Wioletta Kośnik, Roman Gajda, Krzysztof Woźniak, Aleksandra Skoczeń, Anna Kajetanowicz, Karol Grela
Three mono-N-heterocyclic carbene (NHC) ruthenium 2-isopropoxybenzylidene (10 a-c) and one bis(NHC) indenylidene complex (8) bearing an unsymmetrical N-heterocyclic carbene ligand were synthesized and structurally characterized by single-crystal X-ray diffraction. The catalytic activity of the newly obtained complexes were evaluated in ring-closing metathesis (RCM) and ene-yne (RCEYM) reactions in toluene and environmentally friendly 2-MeTHF under air. The results confirmed that although all tested reactions can be successfully mediated by catalysts 10 a-c, their general reactivity is lower than the benchmark all-purpose Ru catalysts with symmetrical NHC ligands...
September 19, 2018: Chemistry: a European Journal
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