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Chemical Science

Yong-Kyun Sim, Heetae Jung, Su Hyun Kim, Jung-Woo Park, Woo-Jin Park, Chul-Ho Jun
A simple, one-step method for covalent bond immobilization of biomolecules on silica operated in water is described. In the approach, an NHS-ester linked methallylsilane is utilized as a bifunctional linker to couple the biomolecule to the silica surface. Weak organic acid such as acetic acid activates the silica surface enough to react with bifunctional linker without destroying activity of biomolecule.
November 7, 2018: Chemical Science
Belinda Pettersson Rimgard, Jens Föhlinger, Jonas Petersson, Marcus Lundberg, Burkhard Zietz, Ann Marie Woys, Stephen A Miller, Michael R Wasielewski, Leif Hammarström
Interligand electron transfer (ILET) of the lowest metal-to-ligand charge transfer (MLCT) state of N712 ( cis -[Ru(dcb)2 (NCS)2 ]4- , where dcb = 4,4'-dicarboxylate-2,2'-bipyridine) in a deuterated acetonitrile solution has been studied by means of femtosecond transient absorption anisotropy in the mid-IR. Time-independent B3LYP density functional calculations were performed to assign vibrational bands and determine their respective transition dipole moments. The transient absorption spectral band at 1327 cm-1 , assigned to a symmetric carboxylate stretch, showed significant anisotropy...
November 7, 2018: Chemical Science
Teck Chuan Lim, Shuting Cai, Roland G Huber, Peter J Bond, Priscilla Xian Siew Chia, Siv Ly Khou, Shujun Gao, Su Seong Lee, Song-Gil Lee
Controlling glycosaminoglycan (GAG) activity to exploit its immense potential in biology ultimately requires facile manipulation of sulfation patterns associated with GAGs. However, satisfying this requirement in full remains challenging, given that synthesis of GAGs is technically arduous while convenient GAG mimetics often produce sulfation patterns that are uncharacteristic of GAGs. To overcome this, we develop saccharide-free polyproline-based GAG mimetics (PGMs) that can be facilely assembled via amide coupling chemistry...
November 7, 2018: Chemical Science
Stephanie H Carpenter, Tessa M Baker, Salvador B Muñoz, William W Brennessel, Michael L Neidig
The first direct syntheses, structural characterizations, and reactivity studies of iron-phenyl species formed upon reaction of Fe(acac)3 and PhMgBr in THF are presented. Reaction of Fe(acac)3 with 4 equiv. PhMgBr in THF leads to the formation of [FePh2 (μ-Ph)]2 2- at -80 °C, which can be stabilized through the addition of N -methylpyrrolidone. Alternatively, at -30 °C this reaction leads to the formation of the tetranuclear iron-phenyl cluster, Fe4 (μ-Ph)6 (THF)4 . Further synthetic studies demonstrate that analogous tetranuclear iron clusters can be formed with both 4-F-PhMgBr and p -tolylMgBr, illustrating the generality of this structural motif for reactions of simple ferric salts and aryl Grignard reagents in THF...
November 7, 2018: Chemical Science
Partha Samanta, Priyanshu Chandra, Subhajit Dutta, Aamod V Desai, Sujit K Ghosh
Detoxification of water has been demonstrated with a viologen-based cationic organic network (compound- 1 ), which was stable not only in water, but also in acidic and basic media. The presence of free exchangeable Cl- ions inside the network of compound- 1 and a high physiochemical stability of the materials offered a suitable scope for the capture of hazardous anionic pollutants from water. Rapid removal of the toxic water pollutant and carcinogenic chromate (CrO4 2- ) from water was shown with compound- 1 ...
October 28, 2018: Chemical Science
Zachary A Kasun, Hiroki Sato, Jing Nie, Yasuyuki Mori, Jon A Bender, Sean T Roberts, Michael J Krische
Ruthenium(0) catalyzed diol-diene benzannulation is applied to the conversion of oligo( p -phenylene vinylenes) 2a-c , 5 and 6 to alternating oligo( o , p -phenylenes) 10a-c , 11-13 . Orthogonality with respect to conventional palladium catalyzed biaryl cross-coupling permits construction of p -bromo-terminated alternating oligo( o , p -phenylenes) 10b , 11-13 , which can be engaged in Suzuki cross-coupling and Scholl oxidation. In this way, structurally homogeneous nanographenes 16a-f are prepared. Nanographene 16a , which incorporates 14 fused benzene rings, was characterized by single crystal X-ray diffraction...
October 28, 2018: Chemical Science
Ping Gong, Gregory A Davidson, Weijun Gui, Kun Yang, William P Bozza, Zhihao Zhuang
Ubiquitination is an essential eukaryotic post-translational modification that regulates various cellular processes. The removal of ubiquitin from its target protein is catalyzed by deubiquitinating enzymes (DUBs). Although it was proposed that many DUBs specifically interact and recognize ubiquitinated proteins as substrates, more direct evidence is needed to support this notion. Here we report protein-targeting activity-based DUB probes that allowed the identification of DUBs recognizing monoubiquitinated proliferating cell nuclear antigen (PCNA) in Saccharomyces cerevisiae ...
October 28, 2018: Chemical Science
Sujoy Rana, Jyoti Prasad Biswas, Asmita Sen, Martin Clémancey, Geneviève Blondin, Jean-Marc Latour, Gopalan Rajaraman, Debabrata Maiti
Non-heme iron based halogenase enzymes promote selective halogenation of the sp3 -C-H bond through iron(iv)-oxo-halide active species. During halogenation, competitive hydroxylation can be prevented completely in enzymatic systems. However, synthetic iron(iv)-oxo-halide intermediates often result in a mixture of halogenation and hydroxylation products. In this report, we have developed a new synthetic strategy by employing non-heme iron based complexes for selective sp3 -C-H halogenation by overriding hydroxylation...
October 28, 2018: Chemical Science
A Klein, S Hank, A Raulf, E F Joest, F Tissen, M Heilemann, R Wieneke, R Tampé
Accurate labeling of endogenous proteins for advanced light microscopy in living cells remains challenging. Nanobodies have been widely used for antigen labeling, visualization of subcellular protein localization and interactions. To facilitate an expanded application, we present a scalable and high-throughput strategy to simultaneously target multiple endogenous proteins in living cells with micro- to nanometer resolution. For intracellular protein labeling, we advanced nanobodies by site-specific and stoichiometric attachment of bright organic fluorophores...
October 28, 2018: Chemical Science
Ming Chen, Xianglong Hu, Junkai Liu, Baixue Li, Nelson L C Leung, Lucia Viglianti, Tsz Shing Cheung, Herman H Y Sung, Ryan T K Kwok, Ian D Williams, Anjun Qin, Jacky W Y Lam, Ben Zhong Tang
The development of new aggregation-induced emission (AIE) systems is a hot research topic, from which functional materials with diversified structures and properties are derived. Here, based on rare, non-emissive and highly electron-withdrawing heteroaromatics of 1,4,5,8-tetraazaanthracene (TAA), experimental and theoretical studies reveal that attaching phenyl rotors to TAA is crucial to creating a new N-type AIE core structure. Furthermore, by covalent attachment of electron-donating aromatic amines to the peripheries of the AIE core, red AIEgens could be obtained readily, which exhibit excellent photostability for long-term lysosome tracking...
October 28, 2018: Chemical Science
Frauke Schibilla, Anna Holthenrich, Boyi Song, Anna Lívia Linard Matos, David Grill, Diego Rota Martir, Volker Gerke, Eli Zysman-Colman, Bart Jan Ravoo
We report cationic Ir(iii) complexes functionalized with adamantyl groups designed to bind to β-cyclodextrin vesicles (CDV) with high affinity ( K a = 1 × 106 M-1 ). The emission of the complexes is tuned by changing the nature of the cyclometalating ligands. The host-guest adduct of CDV and Ir(iii) complexes shows increased and significantly blue-shifted emission due to the lower mobility of the Ir(iii)-complexes residing in the less polar environment of the vesicle surface. Ir(iii)-decorated CDV are efficiently taken up by cells and can be used in live cell imaging...
October 28, 2018: Chemical Science
María J Mayoral, David Serrano-Molina, Jorge Camacho-García, Eva Magdalena-Estirado, Marina Blanco-Lomas, Elham Fadaei, David González-Rodríguez
As molecular self-assembled systems increase in complexity, due to a large number of participating entities and/or the establishment of multiple competing equilibria, their full understanding becomes likewise more complicated, and the use of diverse analytical techniques that can afford complementary information is required. We demonstrate in this work that resonance excitation energy transfer phenomena, measured by fluorescence spectroscopy in combination with other optical spectroscopies, can be a valuable tool to obtain supplementary thermodynamic data about complex supramolecular landscapes that other methods fail to provide...
October 28, 2018: Chemical Science
Qiaomei Wei, Jin Huang, Jing Li, Jiaoli Wang, Xiaohai Yang, Jianbo Liu, Kemin Wang
Here, we have developed a localized catalytic hairpin assembly (LCHA) strategy for intracellular miR-21 imaging by using DNA nanowires confining both hairpin probes in a compact space. The LCHA is constructed by interval hybridization of DNA hairpin probe pairs to a DNA nanowire with multiplex footholds generated by alternating chain hybridization. Compared to the conventional catalytic hairpin assembly (CHA) strategy, the LCHA significantly shortens the reaction time and enhances the sensitivity. Moreover, the proposed LCHA can serve as a carrier for delivery of probes into live cells as well as protect the probes from nuclease degradation and enhances the stability...
October 28, 2018: Chemical Science
Xiucong Bao, Ying Xiong, Xin Li, Xiang David Li
Lysine 3-hydroxyl-3-methylglutarylation (HMG-K) is a newly identified PTM that can occur non-enzymatically in mitochondria. However, the substrate scope of this new PTM remains insufficiently explored, which has greatly hindered the progress in interpreting its regulatory mechanisms and cellular functions. Here, we report the development of an alkyne-functionalized chemical reporter (HMGAM-yne), for the detection and identification of cellular HMGylated proteins. HMGAM-yne is cell-permeable and metabolically incorporated into proteins in living cells...
October 28, 2018: Chemical Science
Juna Bae, Suk Bong Hong
The host-guest interactions in as-made zeolites Y, UZM-4, UZM-22, offretite, ferrierite, phillipsite, EU-12 and levyne, all of which were synthesized using choline as an organic structure-directing agent, have been investigated by a combination of different experimental techniques, including Raman, 1 H-13 C CP MAS NMR and variable-temperature IR spectroscopies, together with theoretical calculations. The conformation of this asymmetric quaternary ammonium cation was shown to differ significantly according to the pore topology of the zeolite host and the intrazeolitic location of the organic guest molecule...
October 28, 2018: Chemical Science
Zhenwei Wei, Xiaochao Zhang, Jinyu Wang, Sichun Zhang, Xinrong Zhang, R Graham Cooks
The identification of trace components from biological media can require derivatization under mild conditions for successful analysis by mass spectrometry (MS). When aqueous droplets ( ca. 500 nL) containing a sugar and an amine as reagents are allowed to evaporate they may form long-lasting microthin films in which derivatization reactions can occur fast relative to reaction rates in bulk solution. Evidence is presented that these reactions are heterogeneous in nature and comparisons are made with reactions in pastes and in neat reagent mixtures...
October 28, 2018: Chemical Science
M Carmen Ortega-Liebana, Jose L Hueso, Rodrigo Fernandez-Pacheco, Silvia Irusta, Jesus Santamaria
Herein we report on a novel inorganic peroxidase-mimicking nanocatalyst activated under blue LED photoirradiation. A novel flash-pyrolysis method has been developed for the generation of strong blue photoluminescence (PL) centers attributed to silicon and carbon-based sites within a mesoporous SBA-15 silica nanorod platform. The type of centers and their PL response can be controlled by varying the flash thermal treatment conditions. By tailoring the operating conditions the system can be driven towards the preferential generation of carbon-based luminescent centers, with or without the simultaneous generation of silicon-based centers...
October 28, 2018: Chemical Science
Supphachok Chanmungkalakul, Vuthichai Ervithayasuporn, Patcharaporn Boonkitti, Alisa Phuekphong, Nicha Prigyai, Sumana Kladsomboon, Suda Kiatkamjornwong
Anthracene-conjugated octameric silsesquioxane (AnSQ) cages, prepared via Heck coupling between octavinylsilsesquioxane (OVS) and 9-bromoanthracene, thermodynamically display intramolecular excimer emissions. More importantly, these hosts are sensitive to each anionic guest, thereby resulting in change of anthracene excimer formation, displaying the solvent-dependent fluorescence and allowing us to distinguish up to four ions such as F- , OH- , CN- and PO4 3- by fluorescence spectroscopy. Depending on the solvent polarity, for example, both F- and CN- quenched the fluorescence emission intensity in THF, but only F- could enhance the fluorescence in all other solvents...
October 28, 2018: Chemical Science
Xiaofan Ji, Wei Chen, Lingliang Long, Feihe Huang, Jonathan L Sessler
Reported here is a two-layer gel construct that permits the on-site detection of the chloride anion by means of a hand-held UV-vis lamp and a smart phone "app". To prepare this system, eight fluorescent polymeric gels G1-G8 were synthesized. Gels G1-G4 containing C4P/imidazolium-F- anion recognition motifs were used to construct a fluorescent pattern (Code A) that may be read out by a smart phone as a 3D color code (Info A). Gels G5-G8, which are based on C4P/imidazolium-Br- anion interactions, were used to construct an array (Code B) that may be read as Info B...
October 28, 2018: Chemical Science
José Ramón Durán Retamal, Dharmaraj Periyanagounder, Jr-Jian Ke, Meng-Lin Tsai, Jr-Hau He
Ever since two dimensional-transition (2D) metal dichalcogenides (TMDs) were discovered, their fascinating electronic properties have attracted a great deal of attention for harnessing them as critical components in novel electronic devices. 2D-TMDs endowed with an atomically thin structure, dangling bond-free nature, electrostatic integrity, and tunable wide band gaps enable low power consumption, low leakage, ambipolar transport, high mobility, superconductivity, robustness against short channel effects and tunneling in highly scaled devices...
October 28, 2018: Chemical Science
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