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https://www.readbyqxmd.com/read/29163924/synthesis-of-a-terminal-ce-iv-oxo-complex-by-photolysis-of-a-ce-iii-nitrate-complex
#1
Mikiyas K Assefa, Guang Wu, Trevor W Hayton
Reaction of [Ce(NR2)3] (R = SiMe3) with LiNO3 in THF, in the presence of 2,2,2-cryptand, results in the formation of the Ce(iii) "ate" complex, [Li(2,2,2-cryptand)][Ce(κ(2)-O2NO)(NR2)3] (1) in 38% yield. Photolysis of 1 at 380 nm affords [Li(2,2,2-cryptand)][Ce(O)(NR2)3] (2), in 33% isolated yield after reaction work-up. Complex 2 is the first reported example of a Ce(iv) oxo complex where the oxo ligand is not supported by hydrogen bonding or alkali metal coordination. Also formed during photolysis are [Li(2,2,2-cryptand)]2[(μ3-O){Ce(μ-O)(NR2)2}3] (3) and [Li(2,2,2-cryptand)][Ce(OSiMe3)(NR2)3] (4)...
November 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29163923/size-and-charge-effect-of-guest-cations-in-the-formation-of-polyoxopalladates-a-theoretical-and-experimental-study
#2
Zhongling Lang, Peng Yang, Zhengguo Lin, Likai Yan, Ming-Xing Li, Jorge J Carbó, Ulrich Kortz, Josep M Poblet
The development of rational synthetic procedures with desired nuclearity and high selectivity is a critical issue in inorganic chemistry. Here we demonstrate a comprehensive understanding of the template effect induced by metal cations in the formation mechanism of the class of polyoxopalladates ({MPd12L8} nanocube and {MPd15L10} nanostar) by combining computational and experimental techniques. The capture of a M (n+) guest ion by a peripheral palladium(ii)-oxo shell leads to a competition between the parent Pd(2+) addenda ion and the respective guest metal ion...
November 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29163922/bright-and-sensitive-ratiometric-fluorescent-probe-enabling-endogenous-fa-imaging-and-mechanistic-exploration-of-indirect-oxidative-damage-due-to-fa-in-various-living-systems
#3
Kun Dou, Guang Chen, Fabiao Yu, Yuxia Liu, Lingxin Chen, Ziping Cao, Tao Chen, Yulin Li, Jinmao You
As a notorious toxin, formaldehyde (FA) poses an immense threat to human health. Aberrantly elevated FA levels lead to serious pathologies, including organ damage, neurodegeneration, and cancer. Unfortunately, current techniques limit FA imaging to general comparative studies, instead of a mechanistic exploration of its biological role, and this is presumably due to the lack of robust molecular tools for reporting FA in living systems. More importantly, despite being reductive, FA, however, can induce oxidative damage to organisms, thus providing a challenge to the mechanistic study of FA using fluorescence imaging...
November 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29163921/the-short-device-lifetimes-of-blue-pholeds-insights-into-the-photostability-of-blue-ir-iii-complexes
#4
Denis Jacquemin, Daniel Escudero
Using Ir(iii) complexes as dopants in phosphorescent organic light-emitting diodes (PhOLEDs) is the most successful strategy to attain long-lasting and highly-performant electroluminescent devices. Whilst highly efficient blue PhOLEDs are accessible, their limited operational lifetimes still restraint their practical use in lighting and displays. These short lifetimes are directly related to the low intrinsic photostability of blue Ir(iii) complexes. This work uses first principles to unveil the mechanisms of degradation of blue phosphors arising from energetically hot excited states (≅6...
November 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29163920/harnessing-fungal-nonribosomal-cyclodepsipeptide-synthetases-for-mechanistic-insights-and-tailored-engineering
#5
Charlotte Steiniger, Sylvester Hoffmann, Andi Mainz, Marcel Kaiser, Kerstin Voigt, Vera Meyer, Roderich D Süssmuth
Nonribosomal peptide synthetases represent potential platforms for the design and engineering of structurally complex peptides. While previous focus has been centred mainly on bacterial systems, fungal synthetases assembling drugs like the antifungal echinocandins, the antibacterial cephalosporins or the anthelmintic cyclodepsipeptide (CDP) PF1022 await in-depth exploitation. As various mechanistic features of fungal CDP biosynthesis are only partly understood, effective engineering of NRPSs has been severely hampered...
November 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29163919/effects-of-vibrational-excitation-on-the-f-h2o-%C3%A2-hf-oh-reaction-dissociative-photodetachment-of-overtone-excited-f-h-oh
#6
Amelia W Ray, Jianyi Ma, Rico Otto, Jun Li, Hua Guo, Robert E Continetti
The reaction F + H2O → HF + OH is a four-atom system that provides an important benchmark for reaction dynamics. Hydrogen atom transfer at the transition state for this reaction is expected to exhibit a strong dependence on reactant vibrational excitation. In the present study, the vibrational effects are examined by photodetachment of vibrationally excited F(-)(H2O) precursor anions using photoelectron-photofragment coincidence (PPC) spectroscopy and compared with full six-dimensional quantum dynamical calculations on ab initio potential energy surfaces...
November 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29163918/assembly-of-strongly-phosphorescent-hetero-bimetallic-and-trimetallic-2-catenane-structures-based-on-a-coinage-metal-alkynyl-system
#7
Xiao-Yong Chang, Guang-Tao Xu, Bei Cao, Juan-Yu Wang, Jie-Sheng Huang, Chi-Ming Che
Homo-metallic metal alkynyl complexes exhibit interesting catenane structures, but their hetero-metallic catenane counterparts are under-developed. In this work, we report rare examples of bimetallic Au-Cu (DtbpC 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 C(-) ligand; Dtbp = 3,5-di-tert-butylphenyl), Au-Ag ( (t) BuC 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 C(-) ligand), and Au-Cu, Au-Ag (C6-FluoC 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 C(-) ligand; C6-Fluo = 9,9-dihexyl-9H-fluoren-2-yl) complexes as well as a trimetallic Au-Ag-Cu (C6-FluoC 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 C(-) ligand) complex, which feature [2]catenane structures...
November 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29163917/3d-hole-transporting-materials-based-on-coplanar-quinolizino-acridine-for-highly-efficient-perovskite-solar-cells
#8
Mingdao Zhang, Gang Wang, Danxia Zhao, Chengyan Huang, Hui Cao, Mindong Chen
Over the past five years, perovskite solar cells (PSCs) have gained intense worldwide attention in the photovoltaic community due to their low cost and high power conversion efficiencies (PCEs). One of the most significant issues in achieving high PCEs of PSCs is the development of suitable low-cost hole-transporting materials (HTMs). Here, we put forward a new concept of HTMs for PSCs: a 3D structure with a core of coplanar quinolizino acridine, derived from the conventional concept of 2D triphenylamine HTMs...
November 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29163916/a-new-face-of-phenalenyl-based-radicals-in-the-transition-metal-free-c-h-arylation-of-heteroarenes-at-room-temperature-trapping-the-radical-initiator-via-c-c-%C3%AF-bond-formation
#9
Jasimuddin Ahmed, Sreejyothi P, Gonela Vijaykumar, Anex Jose, Manthan Raj, Swadhin K Mandal
The radical-mediated transition metal-free approach for the direct C-H bond functionalization of arenes is considered as a cost effective alternative to transition metal-based catalysis. An organic ligand-based radical plays a key role by generating an aryl radical which undergoes a subsequent functionalization process. The design principle of the present study takes advantage of a relatively stable odd alternant hydrocarbon-based phenalenyl (PLY) radical. In this study, the first transition metal-free catalyzed direct C-H arylation of a variety of heteroarenes such as azoles, furan, thiophene and pyridine at room temperature has been reported using a phenalenyl-based radical without employing any photoactivation step...
November 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29163915/field-deployable-quantitative-rapid-identification-of-active-ebola-virus-infection-in-unprocessed-blood
#10
Kavit Shah, Emma Bentley, Adam Tyler, Kevin S R Richards, Edward Wright, Linda Easterbrook, Diane Lee, Claire Cleaver, Louise Usher, Jane E Burton, James K Pitman, Christine B Bruce, David Edge, Martin Lee, Nelson Nazareth, David A Norwood, Sterghios A Moschos
The West African Ebola virus outbreak underlined the importance of delivering mass diagnostic capability outside the clinical or primary care setting in effectively containing public health emergencies caused by infectious disease. Yet, to date, there is no solution for reliably deploying at the point of need the gold standard diagnostic method, real time quantitative reverse transcription polymerase chain reaction (RT-qPCR), in a laboratory infrastructure-free manner. In this proof of principle work, we demonstrate direct performance of RT-qPCR on fresh blood using far-red fluorophores to resolve fluorogenic signal inhibition and controlled, rapid freeze/thawing to achieve viral genome extraction in a single reaction chamber assay...
November 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29163914/increase-of-enzyme-activity-through-specific-covalent-modification-with-fragments
#11
John F Darby, Masakazu Atobe, James D Firth, Paul Bond, Gideon J Davies, Peter O'Brien, Roderick E Hubbard
Modulation of enzyme activity is a powerful means of probing cellular function and can be exploited for diverse applications. Here, we explore a method of enzyme activation where covalent tethering of a small molecule to an enzyme can increase catalytic activity (kcat/KM) up to 35-fold. Using a bacterial glycoside hydrolase, BtGH84, we demonstrate how small molecule "fragments", identified as activators in free solution, can be covalently tethered to the protein using Michael-addition chemistry. We show how tethering generates a constitutively-activated enzyme-fragment conjugate, which displays both improved catalytic efficiency and increased susceptibility to certain inhibitor classes...
November 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29163913/cross-linking-zr-based-metal-organic-polyhedra-via-postsynthetic-polymerization
#12
Dongsik Nam, Jihyun Huh, Jiyoung Lee, Ja Hun Kwak, Hu Young Jeong, Kyungmin Choi, Wonyoung Choe
Metal organic polyhedra (MOPs) have potential as supramolecular building blocks, but utilizing MOPs for postsynthetic polymerization has not been explored. Although MOPs with flexible organic moieties have been recently reported to target enhanced processability, permanent porosity has not been demonstrated. Here, a novel synthetic strategy involving the cross-linking of MOPs via a covalent bond is demonstrated by exploiting a condensation reaction between the MOP and flexible organic linkers. An amine-functionalized Zr-based MOP is cross-linked with acyl chloride linkers in the crystalline state to form cross-linked MOPs...
November 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29163912/magnetically-activated-adhesives-towards-on-demand-magnetic-triggering-of-selected-polymerisation-reactions
#13
Gemma-Louise Davies, Joseph Govan, Renata Tekoriute, Raquel Serrano-García, Hugo Nolan, David Farrell, Ory Hajatpour, Yurii K Gun'ko
On-demand initiation of chemical reactions is becoming increasingly popular in many areas. The use of a magnetic field to trigger reactions is an intriguing concept, with vast potential in both research and industrial settings, though it remains a challenge as yet unsolved. Here we report the first example of on-demand magnetic activation of a polymerisation process using an anaerobic adhesive formulation as an example of this new approach toward triggering polymerisation reactions using an external magnetic field...
November 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29163911/hyperfine-adjustment-of-flexible-pore-surface-pockets-enables-smart-recognition-of-gas-size-and-quadrupole-moment
#14
Chun-Ting He, Zi-Ming Ye, Yan-Tong Xu, Dong-Dong Zhou, Hao-Long Zhou, Da Chen, Jie-Peng Zhang, Xiao-Ming Chen
The pore size and framework flexibility of hosts are of vital importance for molecular recognition and related applications, but accurate control of these parameters is very challenging. We use the slight difference of metal ion size to achieve continuous hundredth-nanometer pore-size adjustments and drastic flexibility modulations in an ultramicroporous metal-organic framework, giving controllable N2 adsorption isotherm steps, unprecedented/reversed loading-dependence of H2 adsorption enthalpy, quadrupole-moment sieving of C2H2/CO2, and an exceptionally high working capacity for C2H2 storage under practical conditions (98 times that of an empty cylinder)...
November 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29163910/cholesterol-directed-nanoparticle-assemblies-based-on-single-amino-acid-peptide-mutations-activate-cellular-uptake-and-decrease-tumor-volume
#15
Shang Li, Rongfeng Zou, Yaoquan Tu, Junchen Wu, Markita P Landry
Peptide drugs have been difficult to translate into effective therapies due to their low in vivo stability. Here, we report a strategy to develop peptide-based therapeutic nanoparticles by screening a peptide library differing by single-site amino acid mutations of lysine-modified cholesterol. Certain cholesterol-modified peptides are found to promote and stabilize peptide α-helix formation, resulting in selectively cell-permeable peptides. One cholesterol-modified peptide self-assembles into stable nanoparticles with considerable α-helix propensity stabilized by intermolecular van der Waals interactions between inter-peptide cholesterol molecules, and shows 68...
November 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29163909/selective-photocatalytic-hydroxylation-and-epoxidation-reactions-by-an-iron-complex-using-water-as-the-oxygen-source
#16
Bittu Chandra, Kundan K Singh, Sayam Sen Gupta
The iron complex [(bTAML)Fe(III)-OH2](-) (1) selectively catalyses the photocatalytic hydroxylation and epoxidation reactions of alkanes and alkenes, respectively, using water as the oxygen-atom source. Upon the oxidation of unactivated alkanes, which included several substrates including natural products, hydroxylation was observed mostly at the 3° C-H bonds with 3° : 2° selectivity up to ∼100 : 1. When alkenes were used as the substrates, epoxides were predominantly formed with high yields. In the presence of H2(18)O, more than 90% of the (18)O-labelled oxygen atoms were incorporated into the hydroxylated and epoxide product indicating that water was the primary oxygen source...
November 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29163908/photosensitizer-free-visible-light-mediated-gold-catalysed-cis-difunctionalization-of-silyl-substituted-alkynes
#17
Jie-Ren Deng, Wing-Cheung Chan, Nathanael Chun-Him Lai, Bin Yang, Chui-Shan Tsang, Ben Chi-Bun Ko, Sharon Lai-Fung Chan, Man-Kin Wong
A new photosensitizer-free visible light-mediated gold-catalysed cis-difunctionalization reaction is developed. The reaction was chemoselective towards silyl-substituted alkynes with excellent regioselectivity and good functional group compatibility, giving a series of silyl-substituted quinolizinium derivatives as products. The newly synthesized fluorescent quinolizinium compounds, named JR-Fluor-1, possessed tunable emission properties and large Stokes shifts. With unique photophysical properties, the fluorophores have been applied in photooxidative amidations as efficient photocatalysts and cellular imaging with switchable subcellular localization properties...
November 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29163907/nb2%C3%A2-au6-a-molecular-wheel-with-a-short-nb-0000000000000000000000000000000000-0000000000000000000000000000000000-0000000000000000000000000000000000-0000000000000000000000000000000000-0000000000000000000000000000000000-0000000000000000000000000000000000-0000000000000000000000000000000000
#18
Tian Jian, Ling Fung Cheung, Joseph Czekner, Teng-Teng Chen, Gary V Lopez, Wei-Li Li, Lai-Sheng Wang
We report a photoelectron spectroscopy and high-resolution photoelectron imaging study of a bimetallic Nb2Au6(-) cluster. Theoretical calculations, in conjunction with the experimental data, reveal that Nb2Au6(-/0) possess high-symmetry D6h structures featuring a Nb-Nb axis coordinated equatorially by an Au6 ring. Chemical bonding analyses show that there are two π bonds and one σ bond in the Nb2 moiety in Nb2©Au6, as well as five totally delocalized σ bonds. The Nb 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 Nb triple bond is strengthened significantly by the delocalized σ bonds, resulting in an extremely short Nb-Nb bond length comparable to the quintuple bond in gaseous Nb2...
November 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29163906/biosynthesis-of-methyl-proline-containing-griselimycins-natural-products-with-anti-tuberculosis-activity
#19
Peer Lukat, Yohei Katsuyama, Silke Wenzel, Tina Binz, Claudia König, Wulf Blankenfeldt, Mark Brönstrup, Rolf Müller
Griselimycins (GMs) are depsidecapeptides with superb anti-tuberculosis activity. They contain up to three (2S,4R)-4-methyl-prolines (4-MePro), of which one blocks oxidative degradation and increases metabolic stability in animal models. The natural congener with this substitution is only a minor component in fermentation cultures. We showed that this product can be significantly increased by feeding the reaction with 4-MePro and we investigated the molecular basis of 4-MePro biosynthesis and incorporation...
November 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29163905/laboratory-scale-photoredox-catalysis-using-hydrated-electrons-sustainably-generated-with-a-single-green-laser
#20
Robert Naumann, Christoph Kerzig, Martin Goez
The ruthenium-tris-bipyridyl dication as catalyst combined with the ascorbate dianion as bioavailable sacrificial donor provides the first regenerative source of hydrated electrons for chemical syntheses on millimolar scales. This electron generator is operated simply by illumination with a frequency-doubled Nd:YAG laser (532 nm) running at its normal repetition rate. Much more detailed information than by product studies alone was obtained by photokinetical characterization from submicroseconds (time-resolved laser flash photolysis) up to one hour (preparative photolysis)...
November 1, 2017: Chemical Science
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