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Chemistry
Slow magnetic relaxation in five-coordinate spin-crossover cobalt(ii) complexes
Jul 24, 2017   Chemical Communications (Cambridge, England)
Cui HH, Wang J, Chen XT, Xue ZL
Slow magnetic relaxation in five-coordinate spin-crossover cobalt(ii) complexes
Jul 24, 2017
Chemical Communications (Cambridge, England)
We present the first examples of the coexistence of field induced slow magnetic relaxation and spin-crossover observed in five-coordinate cobalt(ii) complexes [Co(12-TMC)(CH3CN)](X)2 (12-TMC = 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane, X = BF4-, 1; PF6-, 2). The direct-current (dc) magnetic data show a gradual and incomplete spin-crossover at high temperature. 1 and 2 display frequency- and temperature-dependent alternating-current (ac) magnetic susceptibility under an applied dc field of 2500 Oe, which originates from the S = 1/2 spin state of Co(ii) ions.
Tracking changes in composition and amount of dissolved organic matter throughout drinking water treatment plants by comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry
Jul 24, 2017   The Science Of The Total Environment
Li C, Wang D, Xu X, Xu M, Wang Z, Xiao R
Tracking changes in composition and amount of dissolved organic matter throughout drinking water treatment plants by comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry
Jul 24, 2017
The Science Of The Total Environment
Dissolved organic matter (DOM) can affect the performance of water treatment processes and produce undesirable disinfection by-products during disinfection. Several studies have been undertaken on the structural characterization of DOM, but its fate during drinking water treatment processes is still not fully understood. In this work, the nontargeted screening method of comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry (GC×GC-qMS) was used to reveal the detailed changes of different chemical classes of compounds in DOM during conventional and advanced drinking water treatment processes at three drinking water treatment plants in China. The results showed that when the dissolved organic carbon removal was low, shifts in the DOM composition could not be detected with the specific ultraviolet absorbance at 254nm, but the changes were clear in the three-dimensional fluorescence excitation-emission matrix or GC×GC-qMS analyses. Coagulation-sedimentation processes selectively removed 37-59% of the nitrogenous compounds, alcohols and aromatic hydrocarbons but increased the concentrations of halogen-containing compounds by 17-26% because of the contact time with chlorine in this step. Filtration was less efficient at removing DOM but preferentially removed 21-60% of the acids. However, other organic matter would be released from the filter (e.g., nitrogenous compounds, acids, and aromatic hydrocarbons). Biological activated carbon (BAC) treatment removed most of the compounds produced from ozonation, particularly ketones, alcohols, halogen-containing compounds and acids. However, it should be noted that certain highly polar or high molecular weight compounds not identified in this study might be released from the BAC bed. After the whole treatment processes, the concentrations of nitrogenous compounds, alcohols, alkenes, aromatic hydrocarbons and ketones were decreased more by the advanced treatment processes than by the conventional treatment processes. Alcohol and ketone removals were probably related to the reduction in protein-like materials. Alkane removal was probably related to the reduction in fulvic acid-like and humic acid-like materials. Copyright © 2017 Elsevier B.V. All rights reserved.
New 1.2 GHz NMR Spectrometers- New Horizons?
Jul 24, 2017   Angewandte Chemie (International Ed. In English)
Schwalbe H
New 1.2 GHz NMR Spectrometers- New Horizons?
Jul 24, 2017
Angewandte Chemie (International Ed. In English)
The latest ultrahigh-field NMR spectrometers are a huge technological challenge that require large financial investments. In his Guest Editorial, Harald Schwalbe justifies the need for spectrometers with higher magnetic field strengths. The important results from previous generations of high-field NMR spectrometers are discussed, and research areas are identified that will benefit from the latest spectrometers. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Elements of Eoarchean life trapped in mineral inclusions
Jul 24, 2017   Nature Add nature.com free-link Cancel
Hassenkam T, Andersson MP, Dalby KN, Mackenzie DMA, Rosing MT
Elements of Eoarchean life trapped in mineral inclusions
Jul 24, 2017
Nature
Metasedimentary rocks from Isua, West Greenland (over 3,700 million years old) contain 13C-depleted carbonaceous compounds, with isotopic ratios that are compatible with a biogenic origin. Metamorphic garnet crystals in these rocks contain trails of carbonaceous inclusions that are contiguous with carbon-rich sedimentary beds in the host rock, where carbon is fully graphitized. Previous studies have not been able to document other elements of life (mainly hydrogen, oxygen, nitrogen and phosphorus) structurally bound to this carbonaceous material. Here we study carbonaceous inclusions armoured within garnet porphyroblasts, by in situ infrared absorption on approximately 10-21 m3 domains within these inclusions. We show that the absorption spectra are consistent with carbon bonded to nitrogen and oxygen, and probably also to phosphate. The levels of C-H or O-H bonds were found to be low. These results are consistent with biogenic organic material isolated for billions of years and thermally matured at temperatures of around 500 °C. They therefore provide spatial characterization for potentially the oldest biogenic carbon relics in Earth's geological record. The preservation of Eoarchean organic residues within sedimentary material corroborates earlier claims for the biogenic origins of carbon in Isua metasediments.
Abnormal pinocytosis and valence-variable behaviors of cerium suggested a cellular mechanism for plant yield reduction induced by environmental cerium
Jul 24, 2017   Environmental Pollution (Barking, Essex : 1987)
Wang L, He J, Yang Q, Lv X, Li J, Chen DDY, Ding X, Huang X, Zhou Q
Abnormal pinocytosis and valence-variable behaviors of cerium suggested a cellular mechanism for plant yield reduction induced by environmental cerium
Jul 24, 2017
Environmental Pollution (Barking, Essex : 1987)
The environmental safety of cerium (Ce) applications in many fields has been debated for almost a century because the cellular effects of environmental Ce on living organisms remain largely unclear. Here, using new, interdisciplinary methods, we surprisingly found that after Ce(III) treatment, Ce(III) was first recognized and anchored on the plasma membrane in leaf cells. Moreover, some trivalent Ce(III) was oxidized to tetravalent Ce(IV) in this organelle, which activated pinocytosis. Subsequently, more anchoring sites and stronger valence-variable behavior on the plasma membrane caused stronger pinocytosis to transport Ce(III and IV) into the leaf cells. Interestingly, a great deal of Ce was bound on the pinocytotic vesicle membrane; only a small amount of Ce was enclosed in the pinocytotic vesicles. Some pinocytic vesicles in the cytoplasm were deformed and broken. Upon breaking, pinocytic vesicles released Ce into the cytoplasm, and then these Ce particles self-assembled into nanospheres. The aforementioned special behaviors of Ce decreased the fluidity of the plasma membrane, inhibited the cellular growth of leaves, and finally, decreased plant yield. In summary, our findings directly show the special cellular behavior of Ce in plant cells, which may be the cellular basis of plant yield reduction induced by environmental Ce. Copyright © 2017 Elsevier Ltd. All rights reserved.
Inflammation-responsive self-regulated drug release from ultrathin hydrogel coating
Jul 24, 2017   Colloids And Surfaces. B, Biointerfaces
He M, Wang Q, Shi Z, Xie Y, Zhao W, Zhao C
Inflammation-responsive self-regulated drug release from ultrathin hydrogel coating
Jul 24, 2017
Colloids And Surfaces. B, Biointerfaces
Heterotopic ossification(HO) is a potential severe complication after many biomaterial implanting surgeries, and the inflammation environment caused by the implanting-associated infections is considered as the main nosogenesis. Herein, an inflammation-responsive drug release system was designed by chemically conjugating indometacin (via ester group) onto hydrogel coating to realize local self-regulated drug release to prevent HO. In our strategy, poly(3-mercaptopropyl)trimethoxysilane-co-acrylic acrylate and polyvinyl alcohol (providing anchoring sites for drug molecules) were firstly synthesized and functionalized with ene-groups, then a hydrogel layer was formed and covalently attached onto thiol-modified substrate via thiol-ene click chemistry, followed by grafting indometacin. A porous structure of the attached hydrogel layer was observed by scanning electron microscopy, and the presence of drug molecules in the hydrogel layer was confirmed by X-ray photoelectron spectroscopy and UV-vis absorption spectra. The drug release could be triggered under the mimicking inflammation environment, and the release rate was responsive to the inflammation degree. In addition, after attaching the hydrogel coating, the substrate showed low cytotoxicity, and high promotion for cell adhesion and proliferation. The excellent hemocompatibility of the hydrogel coating was also demonstrated by prolonged clotting time and suppressed platelet adhesion. This work suggests that the inflammation-responsive indometacin conjugated hydrogel coating has great potential to be used for prophylaxis HO. Copyright © 2017 Elsevier B.V. All rights reserved.
Cobalt fibers anchored with tin disulfide nanosheets as high-performance anode materials for lithium ion batteries
Jul 24, 2017   Journal Of Colloid And Interface Science
Chen X, Huang Y, Zhang K, Zhang W
Cobalt fibers anchored with tin disulfide nanosheets as high-performance anode materials for lithium ion batteries
Jul 24, 2017
Journal Of Colloid And Interface Science
Well-designed hierarchical nanostructured composites consisting of one dimensional cobalt fibers and thin tin disulfide nanosheets were successfully synthesized for the first time through a hydrothermal method. The SnS2 nanosheets were uniformly grown onto the Co fibers and were almost perpendicular to the Co fibers. The composites as one kind anode materials exhibited more remarkable lithium ion storage properties than SnS2 nanosheets. The composites exhibited a capacity of 500.5mAh/g after 100 cycles even at 1000mA/g. The improved electrochemical performance could be assigned to the Co fiber substrate support, which could provide short lithium ion and electron pathways, alleviate large volume expansion, contribute to the capacity, and offer mechanical stability for the anode electrode. This special designing perhaps could lay a foundation for the preparation of high performance lithium ion battery anode materials. Copyright © 2017. Published by Elsevier Inc.
Annotinolide F and lycoannotines A-I, further Lycopodium alkaloids from Lycopodium annotinum
Jul 24, 2017   Phytochemistry
Tang Y, Xiong J, Zou Y, Wang W, Huang C, Zhang HY, Hu JF
Annotinolide F and lycoannotines A-I, further Lycopodium alkaloids from Lycopodium annotinum
Jul 24, 2017
Phytochemistry
Seven lycopodine-type (annotinolide F and lycoannotines A-F), two lycodine-type (lycoannotines G and H), and one fawcettimine-type (lycoannotine I) previously undescribed naturally occurring Lycopodium alkaloids together with thirteen known ones were isolated from the whole plant of Lycopodium annotinum. Their structures and absolute configurations were determined by extensive spectroscopic methods, single-crystal X-ray diffraction, chemical transformation, and electronic circular dichroism (ECD) calculations. Among the isolates, annotinolide F, lycoannotines A and B are unusual 7,8-seco-lycopodane derivatives, and annotinolide F even further possesses a rare 8,5-lactone framework through a lactonization after the C-7/C-8 bond cleavage. Lycoannotine C is an uncommon 8,15-seco lycopodine-type alkaloid, whereas lycoannotine I represents the first example of a naturally occurring C-9/N bond cleavage product of fawcettimine-type alkaloid. Among them, only lycoannotine I was found to show considerable anti-butyrylcholinesterase (anti-BuChE) activity. Copyright © 2017 Elsevier Ltd. All rights reserved.
Sliding-strip microfluidic device enables ELISA on paper
Jul 24, 2017   Biosensors & Bioelectronics
Verma MS, Tsaloglou MN, Sisley T, Christodouleas D, Chen A, Milette J, Whitesides GM
Sliding-strip microfluidic device enables ELISA on paper
Jul 24, 2017
Biosensors & Bioelectronics
This article describes a 3D microfluidic paper-based analytical device that can be used to conduct an enzyme-linked immunosorbent assay (ELISA). The device comprises two parts: a sliding strip (which contains the active sensing area) and a structure surrounding the sliding strip (which holds stored reagents-buffers, antibodies, and enzymatic substrate-and distributes fluid). Running an ELISA involves adding sample (e.g. blood) and water, moving the sliding strip at scheduled times, and analyzing the resulting color in the sensing area visually or using a flatbed scanner. We demonstrate that this device can be used to detect C-reactive protein (CRP)-a biomarker for neonatal sepsis, pelvic inflammatory disease, and inflammatory bowel diseases-at a concentration range of 1-100ng/mL in 1000-fold diluted blood (1-100µg/mL in undiluted blood). The accuracy of the device (as characterized by the area under the receiver operator characteristics curve) is 89% and 83% for cut-offs of 10ng/mL (for neonatal sepsis and pelvic inflammatory disease) and 30ng/mL (for inflammatory bowel diseases) CRP in 1000-fold diluted blood respectively. In resource-limited settings, the device can be used as a part of a kit (containing the device, a fixed-volume capillary, a pre-filled tube, a syringe, and a dropper); this kit would cost ~ $0.50 when produced in large scale (>100,000 devices/week). This kit has the technical characteristics to be employed as a pre-screening tool, when combined with other data such as patient history and clinical signs. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.
Streptavidin-hydrogel prepared by sortase A-assisted click chemistry for enzyme immobilization on an electrode
Jul 24, 2017   Biosensors & Bioelectronics
Matsumoto T, Isogawa Y, Tanaka T, Kondo A
Streptavidin-hydrogel prepared by sortase A-assisted click chemistry for enzyme immobilization on an electrode
Jul 24, 2017
Biosensors & Bioelectronics
A tetrameric streptavidin (SA)-appended LPETG tag was site-specifically linked to azido-containing tri-glycine via sortase A catalysis and the resulting azido-modified SA (SA-N3) was retained in the biotin-binding pocket. SA-N3 was polymerized with dibenzylcyclooctyne-modified branched poly(ethyleneglycol) (DBCO-PEG) using azido-modified branched PEG (N3-PEG) as a spacer via copper-free click chemistry. The resulting SA-based hydrogel exhibited gel-like mechanical properties and could immobilize biotin-modified molecules through biotin-SA affinity. Glucose dehydrogenase (GDH) was immobilized in the SA-based hydrogel, and the hydrogel was then coated on a glassy carbon electrode (GCE) and used for the biocatalytic oxidation of glucose. The designed GCE exhibited better performance and stability compared with GDH chemically adsorbed onto a GCE. In addition, the designed GCE anode and a Pt-carbon cathode were assembled into a glucose/O2 fuel cell that provided a maximum power density and open circuit voltage of 11.8±0.56µWcm-2 and 0.17V, respectively. Copyright © 2017 Elsevier B.V. All rights reserved.
Rapid and reliable determination of p-nitroaniline in wastewater by molecularly imprinted fluorescent polymeric ionic liquid microspheres
Jul 24, 2017   Biosensors & Bioelectronics
Lu X, Yang Y, Zeng Y, Li L, Wu X
Rapid and reliable determination of p-nitroaniline in wastewater by molecularly imprinted fluorescent polymeric ionic liquid microspheres
Jul 24, 2017
Biosensors & Bioelectronics
Rapid and efficient detecting trace amount of environmental p-nitroaniline (p-NA) is in urgent need for security concerns and pollution supervision. In this work we report the use of molecularly imprinted polymeric ionic liquid (MIPIL) microspheres to construct recognizable surfaces for detection of p-NA through fluorescence quenching. The p-NA imprinted microspheres are synthesized by precipitation polymerization upon co-polymerization of 3-(anthracen-9-ylmethyl)-1-vinyl-1H-imidazol-3-ium chloride (Fluorescent IL monomer) with ethyleneglycol dimethacrylate (EGDMA). The electron-rich group alkenyl imidazole in IL functional monomer can dramatically improve the emission of anthracene fluorophore and the π-π stacking, electronic, and hydrogen bond between p-NA and MIPIL can efficiently enhance the selective recognition force. The as-synthesized MIPIL microspheres present spherical shape, high fluorescence emission intensity and specific recognition, which showed rapid detection rate (1min), stable reusable property (at least 4 time recycles), wonderful selectivity over several structural analogs, wide linear range (10nM to 10M) with a correlation coefficient of 0.992, and excellent sensitivity (LOD, 9nM). As synthesis and surface functionalization of MIPIL microspheres are well established, the methods reported in this work are facile, rapid and efficient for monitoring p-NA in environmental wastewater. Copyright © 2017 Elsevier B.V. All rights reserved.
A preliminary study on the effects of lanthanum (III) on plant vitronectin-like protein and its toxicological basis
Jul 24, 2017   Ecotoxicology And Environmental Safety
Wang L, He J, Yang Q, Li X, Wei H, Chen DDY, Huang X
A preliminary study on the effects of lanthanum (III) on plant vitronectin-like protein and its toxicological basis
Jul 24, 2017
Ecotoxicology And Environmental Safety
Vitronectin-like protein (VN) is widely found outside plant plasma membranes. The VN molecular surface contains a large number of active groups that combine strongly with rare earth elements (REEs), which means that VN is a preferential binding target for REEs exhibiting their toxic effects, but the toxicological mechanism remains unknown. This study used transmission electron microscopy, circular dichroism, fluorescence spectrometry, ultraviolet-visible spectroscopy, X-ray photoelectron spectroscopy, and calculational chemistry (homology modeling, molecular dynamics simulation and quantum chemical calculation) to preliminarily investigate the effect of lanthanum [La(III)] as an REE, on the structure of VN and its toxicological mechanism. The results showed that low-concentration La(III) could cause micro-interference to the VN molecular structure through weak interactions, such as electrostatic attraction. High-concentration La(III) formed stable complexes with VN, which changed the average binding energy and electron cloud density of VN, loosened the molecular structure and increased the disorder of VN molecule. The results of building a 3D model of VN and simulating the interaction between La(III) and VN using calculational chemistry showed that La(H2O)73+ in solution could coordinately bind to the carboxyl-/carbonyl-O groups in the negatively charged areas on the VN molecular surface. Furthermore, one or more strong H-bonds were formed to enhance the stability of the La(H2O)73+-VN complexes. In summary, low La(III) concentrations could cause micro-interference to the VN molecular structure, whereas high La(III) concentrations could coordinately bind to VN to form stable La-VN complexes, which destroyed the molecular structure of VN; thus the toxicological basis by which La(III) exhibits its toxic effects is its binding to VN. Copyright © 2017 Elsevier Inc. All rights reserved.
Modifying Surface Chemistry of Metal Oxides for Boosting Dissolution Kinetics in Water by Liquid Cell Electron Microscopy
Jul 24, 2017   ACS Nano
Lu Y, Geng J, Wang K, Zhang W, Ding W, Zhang Z, Xie S, Dai H, Chen FR, Sui M
Modifying Surface Chemistry of Metal Oxides for Boosting Dissolution Kinetics in Water by Liquid Cell Electron Microscopy
Jul 24, 2017
ACS Nano
Dissolution of metal oxides is fundamentally important for understanding mineral evolution and micromachining oxide functional materials. In general, dissolution of metal oxides is a slow and inefficient chemical reaction. Here, by introducing oxygen deficiencies to modify the surface chemistry of oxides, we can boost the dissolution kinetics of metal oxides in water, as in situ demonstrated in a liquid environmental transmission electron microscope (LETEM). The dissolution rate constant significantly increases by 16-19 orders of magnitude, equivalent to a reduction of 0.97-1.11 eV in activation energy, as compared with the normal dissolution in acid. It is evidenced from the high-resolution TEM imaging, electron energy loss spectra, and first-principle calculations where the dissolution route of metal oxides is dynamically changed by local interoperability between altered water chemistry and surface oxygen deficiencies via electron radiolysis. This discovery inspires the development of a highly efficient electron lithography method for metal oxide films in ecofriendly water, which offers an advanced technique for nanodevice fabrication.
Optical properties and mechanofluorochromism of new BODIPY dyes based on the pyridine-pyrimidine hybrid structure
Jul 24, 2017   Dalton Transactions (Cambridge, England : 2003)
Liu Y, Duan J, Qi F, Tian D, Wang X, Liu Z, Huang W
Optical properties and mechanofluorochromism of new BODIPY dyes based on the pyridine-pyrimidine hybrid structure
Jul 24, 2017
Dalton Transactions (Cambridge, England : 2003)
A new family of BODIPY dyes (PPB1-4) based on the pyridine-pyrimidine hybrid structure has been synthesized. These dyes show high cyan fluorescence in hexane with quantum yields (Φf) ranging from 0.33 to 0.90. Interestingly, moderate fluorescence of PPB1-4 is observed in the solid state (Φf, 0.11-0.26). X-ray structure analysis demonstrates that H-aggregation should be responsible for the red-shifted and quenched emission in the solid state. Moreover, PPB1-4 show high contrast and reversible mechanochromic fluorescence based on the proposed mechanism of mechanical stimuli triggered dimer dissolution and formation. In addition, rewritable mechanochromic fluorescence recording media fabricated with PPB4 have been successfully achieved.
Comparing Plasma Phospho Tau, Total Tau, and Phospho Tau-Total Tau Ratio as Acute and Chronic Traumatic Brain Injury Biomarkers
Jul 24, 2017   JAMA Neurology
Rubenstein R, Chang B, Yue JK, Chiu A, Winkler EA,   . . . . . .   , Inoue T, Maas AIR, Menon DK, Schnyer DM, Vassar MJ
Comparing Plasma Phospho Tau, Total Tau, and Phospho Tau-Total Tau Ratio as Acute and Chronic Traumatic Brain Injury Biomarkers
Jul 24, 2017
JAMA Neurology
Annually in the United States, at least 3.5 million people seek medical attention for traumatic brain injury (TBI). The development of therapies for TBI is limited by the absence of diagnostic and prognostic biomarkers. Microtubule-associated protein tau is an axonal phosphoprotein. To date, the presence of the hypophosphorylated tau protein (P-tau) in plasma from patients with acute TBI and chronic TBI has not been investigated. To examine the associations between plasma P-tau and total-tau (T-tau) levels and injury presence, severity, type of pathoanatomic lesion (neuroimaging), and patient outcomes in acute and chronic TBI. In the TRACK-TBI Pilot study, plasma was collected at a single time point from 196 patients with acute TBI admitted to 3 level I trauma centers (4) (AUC = 0.771 and 0.777, respectively). Plasma samples from patients with chronic TBI also showed elevated P-tau levels and a P-tau-T-tau ratio significantly higher than that of healthy controls, with both P-tau indices strongly discriminating patients with chronic TBI from healthy controls (AUC = 1.000 and 0.963, respectively). Plasma P-tau levels and P-tau-T-tau ratio outperformed T-tau level as diagnostic and prognostic biomarkers for acute TBI. Compared with T-tau levels alone, P-tau levels and P-tau-T-tau ratios show more robust and sustained elevations among patients with chronic TBI.
Integral membrane proteins: bottom-up, top-down and structural proteomics
Jul 24, 2017   Expert Review Of Proteomics
Karr U, Simonian M, Whitelegge JP
Integral membrane proteins: bottom-up, top-down and structural proteomics
Jul 24, 2017
Expert Review Of Proteomics
Integral membrane proteins and lipids constitute the bilayer membranes that surround cells and sub-cellular compartments, and modulate movements of molecules and information between them. Since membrane protein drug targets represent a disproportionately large segment of the proteome, technical developments need timely review. Areas covered and literature search strategy: Publically available resources such as Pubmed were surveyed. Bottom-up proteomics analyses now allow efficient extraction and digestion such that membrane protein coverage is essentially complete, making up around one third of the proteome. However, this coverage relies upon hydrophilic loop regions while transmembrane domains are generally poorly covered in peptide-based strategies. Top-down mass spectrometry where the intact membrane protein is fragmented in the gas phase gives good coverage in transmembrane regions, and membrane fractions are yielding to high-throughput top-down proteomics. Exciting progress in native mass spectrometry of membrane protein complexes is providing insights into subunit stoichiometry and lipid binding, and cross-linking strategies are contributing critical in-vivo information. Expert commentary: It is clear from the literature that integral membrane proteins have yielded to advanced techniques in protein chemistry and mass spectrometry, with applications limited only by the imagination of investigators. Key advances toward translation to the clinic are emphasized.
Several [Gd-M] Heterometal-Organic Frameworks with [Gdn] as Nodes: Tunable Structures and Magnetocaloric Effect
Jul 24, 2017   Inorganic Chemistry
Shi PF, Cao CS, Wang CM, Zhao B
Several [Gd-M] Heterometal-Organic Frameworks with [Gdn] as Nodes: Tunable Structures and Magnetocaloric Effect
Jul 24, 2017
Inorganic Chemistry
Tunable structures and magnetocaloric effect (MCE) of seven MOFs with [Gdn] as nodes are explored. The [Gdn] node is realized from mononuclear [Gd] to binuclear paddle-wheel [Gd2], tetranuclear tetrahedral [Gd4], and pentanuclear trigonal bipyramidal [Gd5]. Meanwhile, the magnetic entropy changes from 19.4 to 46.0 J·kg-1·K-1. The results reveal that the effect of magnetic density on MCE plays a dominant role for Gd3+-based compounds, and high spin ground state of Mn2+ (S = 5/2) is more favorable to achieve high MCE than that with Zn2+, Co2+, and Ni2+ (Co2+, S = 3/2; Ni2+, S = 1). To our knowledge, it is the first report that MCE is controlled by various clusters as nodes in MOFs.
Geometric Shape Regulation and Non-Covalent Synthesis of One-Dimensional Organic Luminescent Nano/Micro-Materials
Jul 24, 2017   The Journal Of Physical Chemistry Letters
Song X, Zhang Z, Zhang SF, Wei J, Ye K, Liu Y, Marder TB, Wang Y
Geometric Shape Regulation and Non-Covalent Synthesis of One-Dimensional Organic Luminescent Nano/Micro-Materials
Jul 24, 2017
The Journal Of Physical Chemistry Letters
Non-covalent synthesis of one-dimensional (1D) organic nano/micro-materials with controllable geometric shapes or morphologies and special luminescent/electronic properties is one of the greatest challenges in modern chemistry and material science. Control of non-covalent interactions is fundamental for realizing desired 1D structures and crucial for understanding the functions of these interactions. Here, a series of thiophene-fused phenazines composed of a halogen-substituted π-conjugated plate and a pair of flexible side chains is presented, which displays halogen-dependent 1D self-assemblies. Luminescent 1D twisted wires, straight rods and zigzag wires, respectively, can be generated in sequence when the halogen atoms are varied from the lightest F to the heaviest I. It was demonstrated that halogen-dependent anisotropic non-covalent interactions and mirror-symmetrical crystallization dominated the 1D-assembly behaviors of this class of molecules. The methodology developed in this study provides a potential strategy for constructing 1D organic materials with unique optoelectronic functions.
Ni-Catalyzed Regioselective 1,2-Dicarbofunctionalization of Olefins by Intercepting Heck Intermediates as Imine-Stabilized Transient Metallacycles
Jul 24, 2017   Journal Of The American Chemical Society
Shrestha B, Basnet P, Dhungana RK, Kc S, Thapa S, Sears JM, Giri R
Ni-Catalyzed Regioselective 1,2-Dicarbofunctionalization of Olefins by Intercepting Heck Intermediates as Imine-Stabilized Transient Metallacycles
Jul 24, 2017
Journal Of The American Chemical Society
We disclose a strategy for Ni-catalyzed dicarbofunctionalization of olefins in styrenes by intercepting Heck C(sp3)-NiX intermediates with arylzinc reagents. This approach utilizes a readily removable imine as a coordinating group that plays a dual role of intercepting oxidative addition species derived from aryl halides and triflates to promote Heck carbometalation and stabilizing the Heck C(sp3)-NiX intermediates as transient metallacycles to suppress β-hydride elimination and facilitate transmetalation/reductive elimination steps. This method affords diversely substituted 1,1,2-triarylethyl products that occur as structural motifs in various natural products.
Dynamic Chemistry-based Sensing: A Molecular System for Detection of Saccharide, Formaldehyde and Silver Ion
Jul 24, 2017   Analytical Chemistry
Chang X, Wang Z, Qi Y, Kang R, Cui X, Shang C, Liu K, Fang Y
Dynamic Chemistry-based Sensing: A Molecular System for Detection of Saccharide, Formaldehyde and Silver Ion
Jul 24, 2017
Analytical Chemistry
Development of artificial complex molecular systems is of great importance in understanding complexity in natural processes and for achieving new functionalities. One of the strategies is to create them via optimized utilization of noncovalent interactions and dynamic covalent bonds. We report here on a new complex molecular system, which was constructed by integrating the multiple interactions containing dynamic covalent interaction between 1,2-diol and boronic acid, coordination interaction between silver ion and pyridyl, and an easy accessible reaction between secondary amine and formaldehyde. By employing the three dynamic interactions, a pyrene (Py), a well-known fluorophore, labeled compound, PPB, was designed and synthesized. The compound reacts with fructose (F), a monosaccharide, in aqueous phase and produces a fluorescent adduct, PPB-F, which can be further used as a sensing platform for formaldehyde (FA) and silver ion. The respective dynamic interactions are companied with color changes due to the reversible switching between Py monomer emission and excimer emission. The respective experimental detection limits (DLs) for the three analytes are much lower than 0.2 mM, 0.1 mM and 2.5 μM, respectively. Presence of relevant compounds or ions shows little effect upon the sensing. No doubt, the stuff as presented shows that integration of supramolecular interactions including dynamic covalent bonds can be employed as a general strategy to develop new functional molecular systems or materials.
Self-Assembled Polyprodrug Amphiphile for Subcutaneous Xenograft Tumor Inhibition with Prolonged Acting Time In Vivo
Jul 24, 2017   Macromolecular Bioscience
Chen D, Huang Y, Xu S, Jiang H, Wu J, Jin X, Zhu X
Self-Assembled Polyprodrug Amphiphile for Subcutaneous Xenograft Tumor Inhibition with Prolonged Acting Time In Vivo
Jul 24, 2017
Macromolecular Bioscience
Polymeric drug delivery system termed as "polyprodrug amphiphile" poly(2-methylacryloyloxyethyl phosphorylcholine)-b-poly(10-hydroxy-camptothecin methacrylate (pMPC-b-pHCPT) is developed for the prolonged-acting cancer therapy. It is obtained by two-step reversible addition-fragmentation chain transfer polymerization of zwitterionic monomer MPC and an esterase-responsive polymerizable prodrug methacrylic anhydride-CPT, respectively. This diblock polymer is composed of both antifouling (pMPC) and bioactive (pHCPT) segments and the drug is designed as a building block to construct the polymer skeleton directly. Due to its distinct amphiphilicity, the polymer can self-assemble into micelles with different dynamic sizes by facilely tuning the ratio of MPC/HCPT under physiological conditions. The outer pMPC shell is superhydrophilic to form dense hydrate layer preventing the nanosystem from unwanted nonspecific protein adsorption, which is the main lead cause of the rapid clearance of nanoparticles in vivo, thus facilitating the accumulation of drugs in tumor sites via enhanced permeability and retention effect. The configuration of the polyprodrug amphiphile is confirmed by several measurements. The resistance to albumin adsorption, prolonged plasma retention time, accumulation in tumor sites, and anticancer activity of the micelles is also investigated in vitro and in vivo. This novel amphiphile can be expected as a promising agent for the passive targeted prolonged-acting cancer therapy. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
The synthesis of CuyMnzAl1-zOx mixed oxide as a low-temperature NH3-SCR catalyst with enhanced catalytic performance
Jul 24, 2017   Dalton Transactions (Cambridge, England : 2003)
Yan Q, Chen S, Qiu L, Gao Y, O'Hare D, Wang Q
The synthesis of CuyMnzAl1-zOx mixed oxide as a low-temperature NH3-SCR catalyst with enhanced catalytic performance
Jul 24, 2017
Dalton Transactions (Cambridge, England : 2003)
A new type of low-temperature selective catalytic reduction (SCR) catalyst, CuyMnzAl1-zOx, derived from layered double hydroxides is presented in this contribution. By tuning the Cu/Mn/Al ratio, the optimal catalyst Cu2Mn0.5Al0.5Ox resulted in a NOx conversion of 91.2% at 150 °C, which is much higher than that of all other control catalysts, Cu2AlOx (71.1%), Cu-Mn/γ-Al2O3 (65.23%), and Mn/γ-Al2O3 (59.32%). All samples were characterized in detail using various physico-chemical techniques including XRD, BET, FTIR, TEM, H2-TPR, NH3-TPD, and XPS analyses, and the results revealed that the superior catalytic performance of the Cu2Mn0.5Al0.5Ox catalyst can be attributed to its high specific surface area, high reducibility of MnO2 and CuO species, abundance of surface acid sites, and the good dispersion of MnO2 and CuO species. FTIR analyses of pyridine adsorbed samples revealed that the catalytic activity is proportional to the amount of Lewis acid sites. Cu2Mn0.5Al0.5Ox also showed much higher resistance to 100 ppm SO2 and 5% H2O than the control catalysts. The poisoning mechanism and the regenerability of the Cu2Mn0.5Al0.5Ox catalyst was also investigated. In all, compared with the control catalysts of Cu2AlOx, Cu-Mn/γ-Al2O3, and Mn/γ-Al2O3, the newly designed Cu2Mn0.5Al0.5Ox catalyst is not only more active at low temperatures (100-250 °C), but is also relatively more robust in the presence of SO2 and H2O.
Nonhelical heterometallic [Mo2M(npo)4(NCS)2] string complexes (M = Fe, Co, Ni) with high single-molecule conductance
Jul 24, 2017   Chemical Communications (Cambridge, England)
Chang WC, Chang CW, Sigrist M, Hua SA, Liu TJ, Lee GH, Jin BY, Chen CH, Peng SM
Nonhelical heterometallic [Mo2M(npo)4(NCS)2] string complexes (M = Fe, Co, Ni) with high single-molecule conductance
Jul 24, 2017
Chemical Communications (Cambridge, England)
Using the planar 1,8-naphthyridin-2(1H)-one (Hnpo) ligand, novel nonhelical HMSCs [Mo2M(npo)4(NCS)2] (M = Fe, Co, Ni) were synthesised and they exhibited high single-molecule conductance.
Accurate prediction of energetic properties of ionic liquid clusters using a fragment-based quantum mechanical method
Jul 24, 2017   Physical Chemistry Chemical Physics : PCCP
Liu J, He X
Accurate prediction of energetic properties of ionic liquid clusters using a fragment-based quantum mechanical method
Jul 24, 2017
Physical Chemistry Chemical Physics : PCCP
Accurate prediction of physicochemical properties of ionic liquids (ILs) is of great significance to understand and design novel ILs with unique properties. This study employed the electrostatically embedded generalized molecular fractionation (EE-GMF) method for accurate energy calculation of IL clusters. The accuracy and efficiency of the EE-GMF method are systematically assessed at different ab initio levels (including HF, DFT and MP2) with diverse basis sets. With the fixed charge model for the embedding field, the deviations of the EE-GMF approach from conventional full system calculations are within 2.58 kcal mol-1 for all IL clusters with up to 30 ion pairs (720 atoms), tested in this study. Moreover, this linear-scaling fragment quantum mechanical (QM) method can significantly reduce the total computational cost for post-HF methods. The EE-GMF approach is well-suited for studying the energetic, structural and dynamical properties of ILs using high-level ab initio theories.
The Effect of Pressure on Organic Reactions in Fluids-a New Theoretical Perspective
Jul 24, 2017   Angewandte Chemie (International Ed. In English)
Chen B, Hoffmann R, Cammi R
The Effect of Pressure on Organic Reactions in Fluids-a New Theoretical Perspective
Jul 24, 2017
Angewandte Chemie (International Ed. In English)
This Review brings a new perspective to the study of chemical reactions in compressed fluid media. We begin by reviewing the substantial insight gained from more than 50 years of experimental studies on organic reactions in solution under pressure. These led to a proper estimation of the critical roles of volume of activation (Δ≠ V) and reaction volume (ΔV) in understanding pressure effect on rates and equilibria of organic reactions. A recently developed computational method, the XP-PCM (extreme pressure polarizable continuum model) method, capable of carrying out quantum mechanical calculations of reaction pathways of molecules under pressure, is introduced. A case study of the Diels-Alder cycloaddition of cyclopentadiene with ethylene serves, in pedagogical detail, to describe the methodology. We then apply the XP-PCM method to a selection of other pericyclic reactions, including the parent Diels-Alder cycloaddition of butadiene with ethylene, electrocyclic ring-opening of cyclobutene, electrocyclic ring-closing of Z-hexatriene, the [1,5]-H shift in Z-pentadiene, and the Cope rearrangement. These serve as examples of some of the most common combinations of Δ≠ V and ΔV. Interesting phenomena such as a shift in a transition state along a reaction coordinate, a switch of rate-determining step, and the possible turning of a transition state into a stable minimum are revealed by the calculations. A reaction volume profile, the change in the volume of the reacting molecules as the reaction proceeds, emerges as being useful. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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