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Journal of the American Chemical Society

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https://www.readbyqxmd.com/read/29342352/chemically-defined-antibody-and-small-molecule-drug-conjugates-for-in-vivo-tumor-targeting-applications-a-comparative-analysis
#1
Samuele Cazzamalli, Alberto Dal Corso, Fontaine Widmayer, Dario Neri
We present the first direct comparative evaluation of an antibody-drug conjugate and of a small molecule-drug conjugate for cancer therapy, using chemically-defined products which bind with high-affinity to carbonic anhydrase IX, a marker of tumor hypoxia and of renal cell carcinoma.
January 17, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29342351/organic-mixed-valence-compounds-derived-from-cyclic-alkyl-amino-carbenes
#2
Max M Hansmann, Mohand Melaimi, Guy Bertrand
Readily available room temperature stable organic mixed valence compounds are prepared by one-electron reduction of cyclic bis(iminium) salts [derived from cyclic (alkyl)(amino)carbenes] bridged by various spacers. These compounds show characteristic intervalence charge transfer (IV-CT) bands in the near-infrared (NIR). Cyclic voltammetry, EPR, IR, UV-VIS and X-ray studies, as well as DFT calculations, show that depending on the nature of the spacer, these mixed valence compounds range from class III to borderline class I/II...
January 17, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29342349/membrane-allostery-and-unique-hydrophobic-sites-promote-enzyme-substrate-specificity
#3
Varnavas D Mouchlis, Yuan Chen, J Andrew McCammon, Edward A Dennis
We demonstrate that lipidomics coupled with molecular dynamics reveals unique phospholipase A2 specificity toward membrane phospholipid substrates. We discovered unexpected head-group and acyl-chain specificity for three-major human phospholipases A2. These differences between each enzyme's specificity coupled with molecular dynamicsbased structural and binding studies revealed unique active site and interfacial surface binding moieties for each enzyme that explains the observed specificity at a hitherto inaccessible structural level...
January 17, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29341604/ce3-doping-to-modulate-photoluminescence-kinetics-for-efficient-cspbbr3-nanocrystals-based-light-emitting-diodes
#4
Jisong Yao, Jing Ge, Bo-Ning Han, Kun-Hua Wang, Hong-Bin Yao, Hao-Lei Yu, Jian-Hai Li, Bai-Sheng Zhu, Jizhong Song, Chen Chen, Qun Zhang, Haibo Zeng, Yi Luo, Shu-Hong Yu
Inorganic perovskite CsPbBr3 nanocrystals (NCs) are emerging, highly attractive light emitters with high color purity and good thermal stability for light-emitting diodes (LEDs). Their high photo/electroluminescence efficiencies are very important for fabricating efficient LEDs. Here, we propose a novel strategy to enhance the photo/electroluminescence efficiency of CsPbBr3 NCs through doping of heterovalent Ce3+ ions via a facile hot-injection method. The Ce3+ cation was chosen as the dopant for CsPbBr3 NCs by virtue of its similar ion radius and formation of higher energy level of conduction band with bromine in comparison with the Pb2+ cation to maintain the integrity of perovskite structure without introducing additional trap states...
January 17, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29341599/a-ni-catalyzed-carbon-carbon-bond-forming-reductive-amination
#5
Christoph Heinz, J Patrick Lutz, Eric M Simmons, Michael M Miller, William R Ewing, Abigail G Doyle
This report describes a three-component, Ni-catalyzed reductive coupling that enables the convergent synthesis of tertiary benzhydryl amines, which are challenging to access by traditional reductive amination methodologies. The reaction makes use of iminium ions generated in situ from the condensation of secondary N-trimethylsilyl amines with benzaldehydes, and these species undergo reaction with several distinct classes of organic electrophiles. The synthetic value of this process is demonstrated by a single-step synthesis of antimigraine drug flunarizine (Sibelium®) and high yielding derivatization of paroxetine (Paxil®) and metoprolol (Lopressor®)...
January 17, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29341596/core-shell-zif-8-zif-67-derived-cop-nanoparticles-embedded-n-doped-carbon-nanotube-hollow-polyhedron-for-efficient-over-all-water-splitting
#6
Yuan Pan, Kaian Sun, Shoujie Liu, Xing Cao, Konglin Wu, Weng-Chon Cheong, Zheng Chen, Yu Wang, Yang Li, Yunqi Liu, Dingsheng Wang, Qing Peng, Chen Chen, Yadong Li
The construction of highly active and stable non-noble metal electrocatalysts for hydrogen and oxygen evolution reactions electrocatalysts is a major challenge for overall water splitting. Herein, we report a novel hybrid nanostructure with CoP na-noparticles (NPs) embedded in N-doped carbon nanotube hollow polyhedron (NCNHP) through a pyrolysis-oxidation-phosphidation strategy derived from core-shell ZIF-8@ZIF-67. Benefiting from the synergistic effects between highly active CoP NPs and NCNHP, the CoP/NCNHP hybrid exhibited outstanding bifunctional electrocatalytic performances...
January 17, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29338218/mimicking-the-key-functions-of-photosystem-ii-in-artificial-photosynthesis-for-photoelectrocatalytic-water-splitting
#7
Sheng Ye, Chunmei Ding, Ruotian Chen, Fengtao Fan, Ping Fu, Heng Yin, Xiuli Wang, Zhiliang Wang, Pingwu Du, Can Li
It has been anticipated that learning from nature photosynthesis is a rational and effective way to develop artificial photosynthesis system, but it is still a great challenge. Here, we assembled a photoelectrocatalytic system by mimicking the functions of photosystem II (PSII), with BiVO4 semiconductor as a light-harvester protected by a layered double hydroxide (NiFeLDH) as a hole storage layer, a partially oxidized graphene (pGO) as biomimetic tyrosine for charge transfer, and molecular Co cubane as oxygen evolution complex...
January 17, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29338214/a-tool-for-the-import-of-natural-and-unnatural-nucleoside-triphosphates-into-bacteria
#8
Aaron W Feldman, Emil C Fischer, Michael P Ledbetter, Jen-Yu Liao, John C Chaput, Floyd E Romesberg
Nucleoside triphosphates play a central role in biology, but efforts to study these roles have proven difficult because the levels of triphosphates are tightly regulated in a cell and because individual triphosphates can be difficult to label or modify. In addition, many synthetic biology efforts are focused on the development of unnatural nucleoside triphosphates that perform specific functions in the cellular environment. In general, both of these efforts would be facilitated by a general means to directly introduce desired triphosphates into cells...
January 17, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29338212/catalytic-dehydrogenative-stannylation-of-c-sp-h-bonds-involving-cooperative-sn-h-bond-activation-of-hydrostannanes
#9
Francis Forster, Victoria M Rendón López, Martin Oestreich
The catalytic generation of a stannylium-ion-like tin electrophile by heterolytic cleavage of the Sn-H bond in hydrostannes at the Ru-S bond of Ohki-Tatsumi complexes is reported. Reacting these activated hydrostannanes with terminal acetylenes does not lead to hydrostannylation of the C-C triple bond but to dehydrogenative stannylation of the alkyne terminus. The scope of this rare direct C(sp)-H bond stannylation with hydrostannanes is broad, and a mechanism involving a beta-tin-stabilized vinyl cation having a bridged structure is presented...
January 17, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29338205/control-of-amphiphile-self-assembly-via-bioinspired-metal-ion-coordination
#10
Abigail S Knight, Josefin Larsson, Jing M Ren, Raghida Bou Zerdan, Shay Seguin, Remy Vrahas, Jianfang Liu, Gang Ren, Craig J Hawker
Inspired by marine siderophores that exhibit a morphological shift upon metal coordination, hybrid peptide-polymer conjugates that assemble into different morphologies based on the nature of the metal ion coordination have been designed. Coupling of a peptide chelator, hexahistidine, with hydrophobic oligostyrene allows a modular strategy to be established for the efficient synthesis and purification of these tunable amphiphiles (oSt(His)6). Remarkably, in the presence of different divalent transition metal ions (Mn, Co, Ni, Cu, Zn, and Cd) a variety of morphologies were observed...
January 17, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29338213/selective-dehydrogenative-coupling-of-ethylene-to-butadiene-via-an-iridacyclopentane-complex
#11
Yang Gao, Thomas J Emge, Karsten Krogh-Jespersen, Alan S Goldman
An iridium complex is found to catalyze the selective dehydrogenative coupling of ethylene to 1,3-butadiene. The key intermediate, and a major resting state, is an iridacyclopentane. This species undergoes a surprisingly facile β-H elimination, enabled by a partial dechelation (κ3-κ2) of the supporting Phebox ligand.
January 16, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29338207/total-synthesis-of-xylogranatopyridine-b-via-a-palladium-catalyzed-oxidative-stannylation-of-enones
#12
Alexander W Schuppe, David Huang, Yifeng Chen, Timothy R Newhouse
We report a total synthesis of the pyridine-containing limonoid alkaloid (-)-xylogranatopyridine B in 11 steps from commercially available dihydrocarvone. The central pyridine ring was assembled by a late-stage fragment coupling approach employing a modified Liebeskind pyridine synthesis. One fragment was prepared by an allyl-palladium catalyzed oxidative enone β-stannylation, in which the key bimetallic β-stannyl palladium enolate intermediate undergoes a β-hydride elimination. This methodology also allowed introduction of alkyl and silyl groups to the β-position of enones...
January 16, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29338203/a-boron-analogue-of-vinylidene-dication-supported-by-phosphines
#13
Wei Lu, Yongxin Li, Rakesh Ganguly, Rei Kinjo
In the presence of a catalytic amount of heavier tetrylene dichlorides, an allenic diborene (1) undergoes a 1,3-hydrogen shift to afford a terminal diborene (2), which can be deemed a boron analogue of vinylidene dication stabilized by Lewis bases. X-ray diffraction analysis and computational studies revealed that (2) involves a conjugative interaction between the C=C and B=B π-orbitals. The reaction of (2) with ZnBr2 afforded the corresponding isolable complex (3), in which two boon centers coordinate to the Zn atom asymmetrically...
January 16, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29337546/a-mitochondria-specific-fluorescent-probe-for-visualizing-endogenous-hydrogen-cyanide-fluctuations-in-neurons
#14
Lingliang Long, Meiyu Huang, Ning Wang, Yanjun Wu, Kun Wang, Aihua Gong, Zhijian Zhang, Jonathan L Sessler
An ability to visualize HCN in mitochondria in real time may permit additional insights into the critical toxicological and physiological roles this classic toxin plays in living organ-isms. Herein, we report a mitochondria-specific coumarin pyrrolidinium-derived fluorescence probe (MRP1) that permits the real time ratiometric imaging of HCN in living cells. The response is specific, sensitive (detection limit is ca. 65.6 nM), rapid (within 1 s), and reversible. Probe MRP1 contains a ben-zyl chloride subunit designed to enhance retention within the mitochondria under conditions where the mitochondria membrane potential is eliminated...
January 16, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29337545/donor-engineering-for-nir-ii-molecular-fluorophores-with-enhanced-fluorescent-performance
#15
Qinglai Yang, Zhubin Hu, Shoujun Zhu, Rui Ma, Huilong Ma, Zhuoran Ma, Hao Wan, Tong Zhu, Zhengyan Jiang, Weiqiang Liu, Liying Jiao, Haitao Sun, Yongye Liang, Hongjie Dai
Organic fluorophores have been widely used for biological imaging in the visible and the first near-infrared windows. However, their application in the second near-infrared window (NIR-II, 1000-1700 nm) is still limited mainly due to low fluorescence quantum yields (QYs). Here, we explore molecular engineering on the donor unit to develop high performance NIR-II fluorophores. The fluorophores are constructed by a shielding unit-donor(s)-acceptor-donor(s)-shielding unit structure. Thiophene is introduced as the second donor connected to the shielding unit, which can increase the conjugation length and red-shift the fluorescence emission...
January 16, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29337544/pushing-up-the-size-limit-of-metal-chalcogenide-supertetrahedral-nanocluster
#16
Xiaofan Xu, Wei Wang, Dongliang Liu, Dandan Hu, Tao Wu, Xianhui Bu, Pingyun Feng
The cubic ZnS structure type and the size-dependent properties of related nanoparticles are of both fundamental and technological importance. Yet, it remains a challenge to synthesize large atom-precise clusters of this structure type. Currently, only supertetrahedral clusters with 4, 10, 20, and 35 metal sites (denoted as T2, T3, T4, and T5, respectively) are known. Because the synthesis of T5 in 2002, numerous synthetic efforts targeting larger clusters only resulted in T2-T5 clusters in various compositions and intercluster connectivity, with T6 (56 metal and 84 anion sites) being elusive...
January 16, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29337542/a-domino-process-towards-functionally-dense-quaternary-carbons-through-pd-catalyzed-decarboxylative-csp3-csp3-bond-formation
#17
Wusheng Guo, Rositha Kuniyil, José Enrique Gómez, Feliu Maseras, Arjan W Kleij
An efficient protocol was developed to construct functionally dense quaternary carbons with concomitant formation of a new Csp3-Csp3 bond via Pd-catalyzed decarboxylative transformation of vinyl cyclic carbonates. This redox neutral catalytic system features stereocontrolled formation of multi-substituted allylic scaffolds with an aldehyde functionality generated in situ, and it typically can be performed at room temperature without any additives. DFT calculations provide a rationale towards the selective formation of these compounds, and revealed a complex mechanism that is able to reproduce with the help of microkinetic models the non-trivial dependence between the identity of the product and the nature of the substituents in the substrate...
January 16, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29337538/sustainable-polyester-elastomers-from-lactones-synthesis-properties-and-enzymatic-hydrolyzability
#18
Guilhem X De Hoe, Michael T Zumstein, Brandon J Tiegs, Jacob P Brutman, Kristopher McNeill, Michael Sander, Geoffrey W Coates, Marc A Hillmyer
Chemically cross-linked elastomers are an important class of polymeric materials with excellent temperature and solvent resistance. However, nearly all elastomers are petroleum-derived and persist in the environment or in landfills long after they are discarded; this work strives to address these issues by demonstrating the synthesis of renewable, enzymatically hydrolyzable, and mechanically competitive polyester elastomers. The elastomers described were synthesized using a novel bis(β-lactone) cross-linker and star-shaped, hydroxyl-terminated poly(γ-methyl-ε-caprolactone)...
January 16, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29337536/correction-to-adaptation-in-constitutional-dynamic-libraries-and-networks-switching-between-orthogonal-metalloselection-and-photoselection-processes
#19
Ghislaine Vantomme, Shimei Jiang, Jean-Marie Lehn
No abstract text is available yet for this article.
January 16, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29337535/anion-mediated-photophysical-behavior-in-a-c60-fullerene-3-rotaxane-shuttle
#20
Timothy A Barendt, Ilija Rašović, Maria A Lebedeva, George A Farrow, Alexander Auty, Dimitri Chekulaev, Igor V Sazanovich, Julia A Weinstein, Kyriakos Porfyrakis, Paul D Beer
By addressing the challenge of controlling molecular motion, mechanically interlocked molecular machines are primed for a variety of applications in the field of nanotechnology. Specifically, the designed manipulation of communication pathways between electron donor and acceptor moieties that are strategically integrated into dynamic photoactive rotaxanes and catenanes may lead to efficient artificial photosynthetic devices. In this pursuit, a novel [3]rotaxane molecular shuttle consisting of a four station bis-naphthalene diimide (NDI) and central C60 fullerene bis-triazolium axle component and two mechanically bonded ferrocenyl functionalized -isophthalamide anion binding site-containing macrocycles is constructed using an anion template synthetic methodology...
January 16, 2018: Journal of the American Chemical Society
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