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A new palladium-catalyzed domino approach for the synthesis of attractive spirocyclic indolines and dihydrobenzofurans was developed. The reaction proceeds through a sequential intramolecular Heck spirocyclization, remote C-H activation, and diazocarbonyl carbene insertion. Various spiroindolines and spirodihydrobenzofurans containing two quartenary carbon stereocenters were readily obtained in good to excellent yields. A preliminary study of asymmetric spirocyclization using chiral monophosphoramidite as a ligand was also conducted, enabling access to highly valuable chiral spiroindolines with up to 80% ee. [ABSTRACT FROM AUTHOR]

Chiral propargyl amides are particularly useful structural units in organic synthesis. The enantioselective synthesis of propargyl amide is highly desirable. Conventional approach involves the use of a stoichiometric amount of metal reagent or chiral auxiliary. In comparison, direct alkynylation with terminal alkyne is attractive because it avoids the use of stoichiometric organometallic reagent. The asymmetric coupling of aldehyde, amine, and alkyne (A3-coupling) provides an efficient method for the synthesis of N-alkyl and N-arylsubstituted propargyl amines, but this strategy is not amenable for the direct enantioselective synthesis of propargyl amide. We have developed a new strategy and report here a Rh-catalyzed asymmetric hydroalkynylation of enamides. Alkynylations occur regioselectively at the α position of an enamide to produce chiral propargyl amides. High yield and enantioselectivity were observed. Previous alkynylation methods to prepare chiral propargyl amine involve the nucleophilic addition to an electrondeficient imine. In contrast, our current approach proceeds through regioselective hydroalkynylation of an electron-rich alkene. Kinetic studies indicated that migratory insertion of the enamide to the rhodium hydride is turnover limiting. Computational studies revealed the origin of regio- and enantioselectivities. This novel strategy provides an efficient method to access chiral propargyl amides directly from terminal alkynes. [ABSTRACT FROM AUTHOR]

A new DTBP/Mg(NO3)2-mediated bicyclization cascade of o-arylalkynylanilines with secondary arylphosphine oxides has been developed, enabling dual C(sp2)-H functionalization along with the cleavage of the C-N bond. The combination between regioselective P-centered radical-triggered [3 + 2] cyclization and C-centered radical-induced cross-coupling in a one-pot manner delivered 27 examples of tribenzo[b,e,g]phosphindole oxides with generally high regioselectivity. A reasonable mechanism for forming such products involving radical addition-cyclization cascade is proposed. [ABSTRACT FROM AUTHOR]

A new C-center radical-triggered bicyclization cascade of N-tethered 1,7-enynes for forming 28 examples of biologically interesting spirocyclohexadienone-containing cyclopenta[c]quinolin-4-ones with two all-carbon quaternary stereocenters has been established under mild conditions. The in situ generated diazonium salts from 4-methoxyanilines and t-BuONO are served as 4-methoxyphenyl precursors without additional oxidant, enabling 6-exo-dig cyclization/5-exo-trigipso-cyclization to construct three new C-C bonds through metal-free dearomatization. The reaction also features broad substrate scope, annulation efficiency, and high functional group tolerance. [ABSTRACT FROM AUTHOR]

There is a great demand to measure protein-ligand interactions in rapid and low cost way. Here, we developed a microfluidic droplet-based thermal shift assay (dTSA) system for high-throughput screening of small-molecule protein ligands. The system is composed of a nanoliter droplet array chip, a microfluidic droplet robot, and a real-time fluorescence detection system. Total 324 assays could be performed in parallel in a single chip with an 18 x 18 droplet array. The consumption of dTSA for each protein or ligand sample was only 5 nL (femtomole scale), which is significantly reduced by over 3 orders of magnitude compared with those in 96- or 384-well plate-based systems. We also observed the implementation of TSA in nanoliter droplet format could substantially improve assay precision with relative standard deviation (RSD) of 0.2% (n = 50), which can be ascribed to the enhanced thermal conduction in small volume reactors. The dTSA system was optimized by studying the effect of droplet volumes, as well as protein and fluorescent dye (SYPRO Orange) concentrations. To demonstrate its potential in drug discovery, we applied the dTSA system in screening inhibitors of human thrombin with a commercial library containing 100 different small molecule compounds, and two inhibitors were successfully identified and confirmed. [ABSTRACT FROM AUTHOR]

With the use of a simple sulfur-olefin ligand, a highly enantioselective rhodium-catalyzed addition of arylboroxines to N,N-dimethylsulfamoyl-protected aldimines has been achieved, allowing access to a broad range of chiral diarylmethylamines in high yields (up to 98%) with uniformly excellent enantioselectivities (up to 99% ee). This catalyst system is also applicable to the arylation of N-tosyl arylimines. By utilizing this method, some biologically active molecules possessing a chiral 1-aryl-1,2,3,4-tetrahydroisoquinoline core such as Solifenacin and (S)-(+)-Cryptostyline II are facilely constructed. [ABSTRACT FROM AUTHOR]

Here we developed the surface-assisted multifactor fluid segmentation (SAMFS), an automated, fast, and flexible approach for generating a two-dimensional droplet array with tunable droplet volumes, for multivolume digital polymerase chain reaction (PCR). The SAMFS was developed based on the combination of robotic liquid handling and surface-assisted droplet generation techniques, where a continuous aqueous stream that flowed out from a capillary probe was segmented and immobilized on hydrophilic micropillars of a microchip into massive oil-covered droplets with the probe rapidly scanning over the microchip. We studied various factors affecting the droplet generation process, including micropillar top area, distance between adjacent micropillars, aqueous stream flow rate, and microchip moving speed, and demonstrated a high droplet generation throughput up to 50 droplets/s and a largest droplet volume adjusting range from 0.25 to 350 nL. The SAMFS approach was adopted to form an oil-covered array of 994 droplets with four different volumes (1.2, 6, 30, and 150 nL droplets) required for multivolume digital PCR within 8 min. The droplet array system was applied in absolute quantification of plasmid DNA under the multivolume digital PCR mode with a dynamic range spanning 4 orders of magnitude, as well as measurement of HER2 expression levels in different breast cancer cell lines. The results are consistent to those obtained by quantitative real-time PCR method, while the present one has higher precision. [ABSTRACT FROM AUTHOR]

A base-free process to access indole-fused polyheterocycles via a highly efficient and atom-economic palladium-catalyzed intramolecular cross dehydrogenetive coupling (CDC) reaction of 4-aniline substituted coumarins, quinolinones, and pyrones has been developed. A wide range of indolo[3,2-c]coumarins, indolo[3,2-c]quinolinones, and indolo[3,2-c]pyrones can be facilely afforded in good to excellent yields (up to 99%). [ABSTRACT FROM AUTHOR]

The release of nanomaterials into the environment, due to their massive production and application today, has caused ecological and health safety concerns. Semiconductor photocatalysts like TiO2 exhibit cytotoxicity to bacterial cells when exposed to UV irradiation. However, information about their impacts on individual or group bacterial behaviors is limited. In this work, the biofilm formation of Escherichia coli K12 in the presence of TiO2 with and without UV irradiation was investigated and biofilm formation was found not to be affected under the sole application of TiO2 or UV irradiation. However, biofilm development was substantially delayed by TiO2 under UV irradiation, although no obvious cytotoxicity to cell growth was observed. The reactive oxygen species photogenerated by TiO2 were found to quench the autoinducer 2 (AI-2) signals secreted by E. coli K12. As a result, the initiation of quorum sensing for biofilm formation activated by AI-2 was restrained. The expressions of two biofilm-formation-related genes, motA and rcsB, were also suppressed. A dose of an AI-2 precursor, 4,5-dihydroxy-2,3-pentanedione, effectively restored the biofilm development. These results show that the photoexcited TiO2 could suppress biofilm formation through quenching AI-2 signals. This work may facilitate a better understanding about the ecological effects of increasingly released nanomaterials and provide implications for development of antifouling membranes. [ABSTRACT FROM AUTHOR]

Organic molecular cage (CC3-R) with intrinsically porous skeleton is used as a support for immobilizing Rh nanoparticles (NPs) in an ultrasmall size of ~1.1 nm for the first time. The CC3-R with the unique characteristic of high solubility can be utilized to homogenize the heterogeneous catalyst in solution. The obtained homogenized heterogeneous catalyst Rh/CC3-R-homo exhibits significantly enhanced catalytic performance toward various liquid-phase catalytic reactions, as compared with the heterogeneous counterpart Rh/CC3- R-hetero. Moreover, Rh/CC3-R-homo shows excellent durability and recyclability. The advantage of combining homogeneous and heterogeneous catalysts is likely to be beneficial for many applications. [ABSTRACT FROM AUTHOR]

A redox-active diamine ligand, 4,4'-bis(di-p-anisylamino)-2,2'-bipyridine (NNbpy), has been prepared. Electrochemical and spectroscopic studies suggest that little electronic coupling is present between two amine groups in NNbpy. After chelation with Ru(bpy)2 (bpy is 2,2'-bipyridine), the resulting complex displays two N·+/0 processes at +1.02 and +1.16 V versus Ag/AgCl. In the mixed-valent state, rich near-infrared absorptions have been observed, which are believed to consist of multiple metal-to-ligand charge transfer and intervalence charge transfer transitions in the low-energy region. These results suggest that the amine-amine electronic coupling has been enhanced by chelation with Ru(bpy)2. In contrast, no efficient electronic coupling can be realized by chelation with Ir(ppy)2 (ppy is 2'-phenylpyridine) or Re(CO)3Cl. A ruthenium ion-mediated electron transfer mechanism, instead of through-space coupling, has been proposed to explain this phenomenon. For the purpose of comparison, a monoamine-substituted bpy ligand and corresponding Ru(bpy)2 complex have been synthesized and studied. In addition, EPR, DFT, and TDDFT studies have been performed to complement the experimental results [ABSTRACT FROM AUTHOR]

In the addition of TMEDA in toluene, aryl Grignards could effectively and site-specifically ortho-arylate electron-deficient heteroarenes under mild conditions. This endeavor successfully changed the old low-yielding reaction, aryl Grignard addition to N-heteroarenes, into an efficient procedure for heterobiaryls. The combination of the inexpensive aryl Grignards, TMEDA, the cost-free air, no use of any transition-metal catalyst, the mild reaction conditions, and the high-yielding gram-scale results enables this new procedure to be cost-effective and potentially utilizable in industry. [ABSTRACT FROM AUTHOR]

Metal--organic frameworks (MOFs) and related material classes are attracting considerable attention for their applications in gas storage/separation as well as catalysis. In contrast, research concerning potential uses in electronic devices (such as sensors) is in its infancy, which might be due to a great challenge in the fabrication of MOFs and semiconductor composites with well-designed structures. In this paper, we proposed a simple self-template strategy to fabricate metal oxide semiconductor(@MOF core--shell heterostructures, and successfully obtained freestanding ZnO@ZIF-8 nanorods as well as vertically standing arrays (including nanorod arrays and nanotube arrays). In this synthetic process, ZnO nanorods not only act as the template but also provide Zn2+ ions for the formation of ZIF-8. In addition, we have demonstrated that solvent composition and reaction temperature are two crucial factors for successfully fabricating well-defined ZnO@ZIF-8 heterostructures. As we expect, the as-prepared ZnO@ZIF-8 nanorod arrays display distinct photoelectrochemical response to hole scavengers with different molecule sizes (e.g., H2O2 and ascorbic acid) owing to the limitation of the aperture of the ZIF-8 shell. Excitingly, such ZnO@ZIF-8 nanorod arrays were successfully applied to the detection of H2O2 in the presence of serous buffer solution. Therefore, it is reasonable to believe that the semiconductor@MOFs heterostructure potentially has promising applications in many electronic devices including sensors. [ABSTRACT FROM AUTHOR]

A polyazine ligand, 5,5′-di(1-butyl-1,2,3-triazol-4-yl)-2,2′-bipyridine(Bu-dtabpyH), has been prepared by a “click” reaction.The treatment of Bu-dtabpyH with [Ru(bpy)2Cl2] affords complex [Ru(bpy)2(Bu-dtabpyH)]2+(bpy= 2,2′-bipyridine), which has been characterized by single-crystalX-ray analysis. The reaction of [Ru(bpy)2(Bu-dtabpyH)]2+with another equivalent of [Ru(bpy)2Cl2] in the presence of AgOTf gives a redox-asymmetric bisrutheniumcomplex, [Ru(bpy)2(Bu-dtabpy)Ru(bpy)2]3+(Bu-dtabpy is the 4-deprotonated form of Bu-dtabpyH), with one rutheniumatom binding to the pyridin-4-yl bridge with a Ru–N bond andthe other with a Ru–C bond. This complex displays two Ru(II/III)redox couples at +0.79 and +1.28 V vs Ag/AgCl. After being transformedinto a mixed-valence species, [Ru(bpy)2(Bu-dtabpy)Ru(bpy)2]4+, by one-electron oxidation, it exhibits a moderatemetal-to-metal charge-transfer band around 1300 nm. Density functionaltheory and time-dependent density functional theory calculations havebeen carried out for the model complex [Ru(bpy)2(Me-dtabpy)Ru(bpy)2]3+and the mixed-valence state [Ru(bpy)2(Me-dtabpy)Ru(bpy)2]4+to complement theseexperimental results, where Me-dtabpy is the 4-deprotonated form of5,5′-di(1-methyl-1,2,3-triazol-4-yl)-2,2′-bipyridine. [ABSTRACT FROM AUTHOR]

A series of biscyclometalated ruthenium complexes bridged by the title ligand were prepared by either an oxidative dimerization of corresponding monometallic complexes or treatment of the bridging ligand with Ru(L)Cl3 (L = capping ligand). The electronic properties of these complexes were examined by electrochemical and spectroscopic analysis and DFT/TDDFT calculations. The degree of metal-metal electronic coupling of these complexes was estimated on the basis of intervalence charge-transfer transition analysis of corresponding mixed-valent complexes. These studies indicated that the electronic coupling was strongly dependent on the electronic nature of the terminal ligands. A hole-transfer superexchange mechanism was used to understand the underlying electron-transfer processes. [ABSTRACT FROM AUTHOR]

The linear bis-cyclometalated Ru(II) complex [(ttpy)Ru(ttabp)Ru(ttpy)]2+was prepared from the oxidative coupling of the monometalliccomplex [(ttpy)Ru(dtab)]+in good yield, where ttpy is4′-tolyl-2,2′:6′,2″-terpyridine, ttabpis 3,3′,5,5′-tetrakis(1-butyl-1H-1,2,3-triazol-4-yl)biphenyl,and dtab is 1,3-bis(1-butyl-1H-1,2,3-triazol-4-yl)benzene.The electronic properties of these two complexes were studied andcompared by electrochemical and spectroscopic methods and DFT/TDDFTcalculations. The complex [(ttpy)Ru(ttabp)Ru(ttpy)]2+showedtwo consecutive RuII/IIIredox waves at +0.34 and +0.51V vs Ag/AgCl with a comproportionation constant Kcof 760. One-electron oxidation of [(ttpy)Ru(ttabp)Ru(ttpy)]2+by electrochemical methods produced the mixed-valent complex[(ttpy)Ru(ttabp)Ru(ttpy)]3+, which exhibited a symmetricintervalence charge transfer band at 1800 nm (νmax= 5550 cm–1, εmax= 5100 M–1cm–1, Δν1/2= 3580 cm–1). The energy and shape of this bandare very similar in the different solvents studied (CH3CN, DMF, CH2Cl2). [(ttpy)Ru(ttabp)Ru(ttpy)]3+was determined to be a class II/III borderline system withthe electronic coupling parameter Hab=530 cm–1. It displayed a metal-centered rhombicEPR signal at 77 K with an isotropic gfactor of2.109 and total ganisotropy of 0.256, which pointsto an appreciable spin distribution on the bridging ligand in additionto the metal centers. [ABSTRACT FROM AUTHOR]

A dimetallic biscyclometalated ruthenium complex, [(bpy)2Ru(dpb)Ru(bpy)2]2+ (bpy = 2,2'-bipyridine; dpb = 1,4-di-2-pyridylbenzene), with a tris-bidentate coordination mode has been prepared. The electronic properties of this complex were studied by electrochemical and spectroscopic analysis and DFT/TDDFT calculations on both rac and meso isomers. Complex [(bpy)2Ru(dpb)Ru(bpy)2]2+ has a similar 1,4-benzenedicyclometalated ruthenium (Ru-phenyl-Ru) structural component with a previously reported bis-tridentate complex, [(tpy)Ru(tpb)Ru(tpy)]2+ (tpy = 2,2';6',2?-terpyridine; tpb = 1,2,4,5-tetra-2-pyridylbenzene). The charge delocalizations of these complexes across the Ru-phenyl-Ru array were investigated and compared by studying the corresponding one-electron-oxidized species, generated by chemical oxidation or electrochemical electrolysis, with DFT/TDDFT calculations and spectroscopic and EPR analysis. These studies indicate that both [(bpy)2Ru(dpb)Ru(bpy)2]3+ and [(tpy)Ru(tpb)Ru(tpy)]3+ are fully delocalized systems. However, the coordination mode of the metal component plays an important role in influencing their electronic properties. [ABSTRACT FROM AUTHOR]

A series of asymmetrical bis-tridentate cyclometalated complexes including [Ru(Mebib)(Mebip)]+, [Ru(Mebip)(dpb)]+, [Ru(Mebip)(Medpb)]+, and [Ru(Mebib)(tpy)]+ and two bis-tridentate noncyclometalated complexes [Ru(Mebip)2]2+ and [Ru(Mebip)(tpy)]2+ were prepared and characterized, where Mebib is bis(N-methylbenzimidazolyl)benzene, Mebip is bis(N-methylbenzimidazolyl)pyridine, dpb is 1,3-di-2-pyridylbenzene, Medpb is 4,6-dimethyl-1,3-di-2-pyridylbenzene, and tpy is 2,2′:6′,2″-terpyridine. The solid-state structure of [Ru(Mebip)(Medpb)]+ is studied by X-ray crystallographic analysis. The electrochemical and spectroscopic properties of these ruthenium complexes were studied and compared with those of known complexes [Ru(tpy)(dpb)]+ and [Ru(tpy)2]2+. The change of the supporting ligands and coordination environment allows progressive modulation of the metal-associated redox potentials (RuII/III) from +0.26 to +1.32 V vs Ag/AgCl. The introduction of a ruthenium cyclometalated bond in these complexes results in a significant negative potential shift. The RuII/III potentials of these complexes were analyzed on the basis of Lever’s electrochemical parameters (EL). Density functional theory (DFT) and time-dependent DFT calculations were carried out to elucidate the electronic structures and spectroscopic spectra of complexes with Mebib or Mebip ligands. [ABSTRACT FROM AUTHOR]

A new bridging ligand 1,3,6,8-tetrakis(1-butyl-1H-1,2,3-triazol-4-yl)pyrene (ttapyr) was designed and synthesized by "click" chemistry. This ligand was used to construct a linear dimetallic biscyclometalated Ru(II) complex [(tpy)Ru(ttapyr)Ru(tpy)]2+ and a monometallic complex [(tpy)Ru(ttapyr)]+, where tpy is 2,2′:62′,22″-terpyridine. The electronic properties of these complexes were studied and compared by electrochemical and spectroscopic methods with the aid of DFT calculations. One-electron oxidation of [(tpy)Ru(ttapyr)Ru(tpy)]2+ with cerium ammonium nitrate produced a mixed-valent complex [(tpy)Ru(ttapyr)Ru(tpy)]3+. The intramolecular electronic coupling between individual metal centers was quantified by the intervalence charge transfer transition analysis. Mixed-valent complex [(tpy)Ru(ttapyr)Ru(tpy)]3+ exhibits a metal-centered rhombic EPR signal at 77 K with an average g factor of 2.203. [ABSTRACT FROM AUTHOR]

A tridentate cyclometalating ligand, 1,3-di(1,2,3-triazol-4-yl)benzene (dtab), has been prepared and used for the syntheses of a number of cyclometalated RuIIcomplexes. A comparison of the electrochemical and spectroscopic properties of cyclometalated complexes made from dtab or 1,3-di(2-pyridyl)benzene is presented as well. [ABSTRACT FROM AUTHOR]

The first example of nickel-catalyzed asymmetric Ullmann coupling of bis-ortho-substituted arylhalides is described. With the chiral BINOL-based monodentate phosphoramidite ligand, the reaction allows atropoenantioselective synthesis of a series of axially chiral tetra-ortho-substituted biaryl dials. By taking advantage on this asymmetric Ullman coupling as a key stereogenic axis-forming reaction, the formal synthesis of (+)-isoschizandrin was accomplished. [ABSTRACT FROM AUTHOR]

A novel iron-catalyzed intermolecular decarboxylative Csp3−Csp2coupling reaction using proline derivatives as starting materials is developed. In this process, a series of potentially useful ligands (tertiary aminonaphthol) for catalysis was obtained. [ABSTRACT FROM AUTHOR]

The substitution reactions of M(CH 3CH 2CO 2) 2and Htza afford the crystalline precipitates of [Cd(tza) 2] ( 1), [Mn(tza) 2] ( 2), [Co(tza) 2] ( 3), and β-[Zn(tza) 2] ( 5). The recrystallization of 5leads to the formation of α-[Zn(tza) 2] ( 4). X-ray powder diffraction of 1− 5reveal that 1, 2, 3, and 5are allomers, but 4and 5are isomers, revealing the unprecedented structural transformation during the process of recrystallization. Compounds 1− 4have been characterized by X-ray single-crystal crystallography, IR, and magnetism analysis. Structural analyses and comparison of 1− 4detail the structural evolution of from β-[Zn(tza) 2] ( 5) to α-[Zn(tza) 2] ( 4) and possible driving force has been proposed. The interactions between the Mn IIions of 2have been observed as weakly antiferromagnetic. [ABSTRACT FROM AUTHOR]

Because porous metal oxides with controllable morphologies have been attracting much attention for their potential applications in the fields of adsorption/separation, sensing, energy storage, and conversion, it is highly desirable to prepare new morphology of metal oxides and investigate their performance. In this work, CuO particles with different shapes such as octahedron, sponge-like octahedron, and sphere have been synthesized through thermal decomposition of crystalline Cu(II)-organic frameworks (HKUST-1). The structure and morphology of as-prepared CuO particles have been fully characterized by the usage of XRD, XPS, SEM, and TEM. The gas-sensing behaviors of these CuO samples have been investigated and our results show that CuO-400 with spherical shape displays unprecedented high response (maximum value, 102) for triethylamine (TEA) at 100 ppm with a low detection limit of 5 ppm, a lower working temperature (230 °C), excellent reproducibility, and long-term stability. The highly sensing behavior of CuO-400 sphere might be due to its special structural factor with many open active sites for oxygen adsorption, which could react with TEA molecules more efficiently. Our results clearly suggest that porous CuO particles should be promising candidates for future practical application to detect TEA vapor at relatively low temperature. [ABSTRACT FROM AUTHOR]

A new luminescent terbium-metal-organic framework [Tb3(L)2(HCOO)(H2O)5]·DMF·4H2O (1) (H4L = 4,4′-(pyridine-3,5-diyl)diisophthalic acid) has been successfully assembled by Tb3+ ions and an undeveloped pyridyl-tetracarboxylate. Compound 1 exhibits a 3D porous (3,8)-connected (4.5²)2(4².512.66.75.8³) topological framework with fascinating 1D open hydrophilic channels decorated by uncoordinated Lewis basic pyridyl nitrogen atoms. In particular, the Tb-MOF (1) can detect Cu2+ ions with high selectivity and sensitivity, and its luminescence is nearly entirely quenched in N,N-dimethylformamide (DMF) solution and biological system. In addition, 1 still has high detection for the trace content of nitromethane with 70 ppm, which suggests that 1 is a promising example of dual functional materials with sensing copper ions and nitromethane. [ABSTRACT FROM AUTHOR]

Stimuli-responsivehydrogels have great potentials in biomedicaland biotechnological applications. Due to the advantages of precisecontrol over molecular weight and being biodegradable, protein-basedhydrogels and their applications have been extensively studied. However,protein hydrogels with dual thermosensitive properties are rarelyreported. Here we present the first report of dual thermosensitivehydrogels assembled from the conserved C-terminal domain of spiderdragline silk. First, we found that recombinant C-terminal domainof major ampullate spidroin 1 (MaSp1) of the spider Nephila clavipesformed hydrogels when cooled toapproximately 2 °C or heated to 65 °C. The conformationalchanges and self-assembly of the recombinant protein were studiedto understand the mechanism of the gelation processes using multiplemethods. It was proposed that the gelation in the low-temperatureregime was dominated by hydrogen bonding and hydrophobic interactionbetween folded protein molecules, whereas the gelation in the high-temperatureregime was due to cross-linking of the exposed hydrophobic patchesresulting from partial unfolding of the protein upon heating. Moreinterestingly, genetic fusion of the C-terminal domain to a shortrepetitive region of N. clavipesMaSp1resulted in a chimeric protein that formed a hydrogel with significantlyimproved mechanical properties at low temperatures between 2 and 10°C. Furthermore, the formation of similar hydrogels was observedfor the recombinant C-terminal domains of dragline silk of differentspider species, thus demonstrating the conserved ability to form dualthermosensitive hydrogels. These findings may be useful in the designand construction of novel protein hydrogels with tunable multiplethermosensitivity for applications in the future. [ABSTRACT FROM AUTHOR]

Cyclometalated diruthenium complexes 1(PF6)2–5(PF6)2 bridged by 1,3,6,8-tetra(pyrid-2-yl)-pyrene have been prepared, with the terminal ligand bis(N-methylbenzimidazolyl)pyridine (1(PF6)2), 4′-di-(p-methoxyphenyl)amino-2,2′:6′,2″-terpyridine (2(PF6)2), 4′-p-methoxyphenyl-2,2′:6′,2″-terpyridine (3(PF6)2), 2,2′:6′,2″-terpyridine (4(PF6)2), and trimethyl-4,4′,4″-tricarboxylate-2,2′:6′,2″-terpyridine (5(PF6)2). The single-crystal X-ray structure of 4(PF6)2 is presented. These complexes show two stepwise anodic redox pairs, and the potentials progressively increase from 1(PF6)2 to 5(PF6)2. Complexes 1(PF6)2–4(PF6)2 have comparable electrochemical potential splitting of 200–210 mV, while complex 5(PF6)2 has a splitting of 170 mV. Upon one-electron oxidation by chemical oxidation or electrolysis, the resulting mixed-valent complexes 13+–53+ display broad and intense absorptions between 1000 and 3000 nm. Complexes 13+ and 23+ show the presence of a higher-energy shoulder band in addition to the main near-infrared absorption band. This shoulder band is less distinguished for 33+–53+. Three-state theory has been used to explain this difference. The one-electron oxidized forms, 13+–53+, exhibit rhombic EPR signals at 77 K with the isotropic g values in the range of 2.18–2.24. Density functional theory (DFT) and time-dependent DFT (TDDFT) computations have been performed on 12+–52+ to characterize their electronic structures and rationalize the absorption spectra in a wide energy range. DFT computations on 13+–53+ show that both ruthenium ions and the bridging ligand have comparable spin densities. TDDFT computations on 13+ and 43+ have been performed to complement the experimental results. [ABSTRACT FROM AUTHOR]

The use of alkylsulfanyl and alkylsulfonylside chains are demonstrated to be a useful synthetic strategy fortuning the electronic properties of organic semiconductors, as shownin thienothiophene vinylene polymers. By changing the oxidation stateof sulfanyl to sulfonyl, we lower the HOMO and LUMO energy levelsof our substituted polymers, as well as enhance their fluorescence.Fine-tuning of the energy levels was achieved by combining sulfanyland sulfonyl substituted thienothiophene monomers through random polymerization,yielding polymers with low-band gaps (1.5 eV) yet benefiting froma structurally uniform conjugated backbone. The effects of these functionalside chains are presented through DFT calculations, UV–vis,fluorescence, and electrochemical measurements, as well as crystallographicanalysis of a sulfanyl-substituted oligomer. The semiconducting propertiesof the new polymers are studied in OFET and OPV devices. [ABSTRACT FROM AUTHOR]

Gas-phase cyclometalation of [ArNi(PPh3) n ]+ (n = 1, 2) complexes have been studied by ESI-MS/MS. The electron-donating substituents of aromatic iodides in the para position were found to inhibit the cyclometalation process of losing ArH, while the electron-withdrawing substituents in the para position were found to enhance it. These results indicate that the cyclometalation process of losing ArH is favored by electron-deficient aromatic groups. In addition, the detailed dissociation pathways of the cationic nickel complexes were studied, and among these pathways, the process of aryl-aryl interchange was also found to proceed in ESI-MS/MS. [Copyright &y& Elsevier]

The currently used hemoperfusion adsorbents such as activated carbon and ion-exchange resin show dissatisfactory hemocompatibility, and a large dose of injected heparin leads to the increasing cost and the risk of systematic bleeding. Natural polysaccharide adsorbents commonly have good biocompatibility, but their application is restricted by the poor mechanical strength and low content of functional groups. Herein, we developed an efficient, self-anticoagulant and blood compatible hemoperfusion adsorbent by imitating the structure and functional groups of heparin. Carrageenan and poly(acrylic acid) (PAA) cross-linked networks were built up by the combination of phase inversion of carrageenan and post-cross-linking of AA, and the formed dual-network structure endowed the beads with improved mechanical properties and controlled swelling ratios. The beads exhibited low protein adsorption amounts, low hemolysis ratios, low cytotoxicity, and suppressed complement activation and contact activation levels. Especially, the activated partial thromboplastin time, prothrombin time, and thrombin time of the gel beads were prolonged over 13, 18, and 4 times than those of the control. The self-anticoagulant and biocompatible beads showed good adsorption capacities toward exogenous toxins (560.34 mg/g for heavy metal ions) and endogenous toxins (14.83 mg/g for creatinine, 228.16 mg/g for bilirubin, and 18.15 mg/g for low density lipoprotein (LDL)), thus, highlighting their potential usage for safe and efficient blood purification. [ABSTRACT FROM AUTHOR]

As an iron oxyhydroxide, nanosized ferrihydrite (Fh) is important in Earth science, biology, and industrial applications. However, its basic structure and origin of its magnetism have long been debated. We integrate synchrotron-based techniques to explore the chemical structures of 2-line ferrihydrite and to determine the origin of its magnetism during hydrothermal aging in air. Our results demonstrate that both the magnetism and X-ray magnetic circular dichroism (XMCD. signal of 2-line ferrihydrite are enhanced with aging time, and that XMCD spectral patterns resemble that of maghemite (γ-Fe2O3) rather than magnetite (Fe3O4). Fe L-edge and K-edge X-ray absorption spectroscopy (XAS) further indicate formation of both maghemite and hematite (α-Fe2O3. with increasing concentrations with longer hydrothermal aging time. Thus, magnetic enhancement with longer hydrothermal aging time is attributed to increasing maghemite concentration instead of a magnetically ordered ferrihydrite as previously reported. Moreover, L-edge and K-edge XAS spectra with different probing depths yield different ratios of these Fe oxides, which suggest the formation of a core (ferrihydrite-rich)-shell (with a mixture of both allotropes; α-Fe2O3 and γ-Fe2O3) structure during hydrothermal aging. Our results provide insights into the chemical evolution of 2-line ferrihydrite that reveal unambiguously the origin of its magnetism. [ABSTRACT FROM AUTHOR]

Numerous drug treatments are available for Parkinson's disease (PD), an age-related neurodegenerative disease, but most cause serious side effects. Therefore, novel therapeutic strategies that halt disease progression and allow for long-term administration are urgently needed. Neuroinflammation critically contributes to the pathogenesis of PD. Here, we report the discovery and optimization of phloroglucinol derivatives, a novel class of anti-neuroinflammatory compounds. Structural modifications of the hit compound 3-methyl-1-(2,4,6-trihydroxyphenyl)butan-1-one produced 43 derivatives, including a preclinical candidate (compound 21), that exhibited potent in vitro anti-neuroinflammatory effects, good blood-brain barrier penetration, and desirable safety margins in mice at a median lethal dose (LD50) <5000 mg/kg. Its in vivo efficacy was demonstrated in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)- and MPTP/probenecid (prob)-induced subacute and chronic PD models, respectively, and α-synuclein transgenic mice. Mechanistic studies revealed neuroinflammation inhibition by targeting Src/phosphatase and tensin homologue deleted on chromosome 10 (PTEN)/Akt signaling might be promising. We highlighted the potential usefulness of phloroglucinol derivatives in PD treatment. [ABSTRACT FROM AUTHOR]

An asymmetric dual-metal relay catalysis strategy that combines Rh/chiral sulfur-olefin-catalyzed enantioselective 1,2-addition with a Pd-catalyzed intramolecular C--O coupling has been developed. The method allows rapid and efficient synthesis of quaternary carbon-containing gem-diaryl benzofuran-3(2H)-ones in good yields in a highly enantioselective manner (up to 99% ee) through a simple one-pot cascade reaction. [ABSTRACT FROM AUTHOR]

Two new three-dimensional (3D) multinodal Cd(II)-organic frameworks, [Cd3(dccpa)(bipy)0.5(H2O)4]·5H2O (1) and [(CH3)2NH2]2[Cd11(dccpa)4(DMF)4(H2O)8]·4H2O (2) (H6dccpa = 3,4-di(3,5-dicarboxyl phenyl) phthalic acid, bipy = 4,4′-bipyridine), have been prepared and fully characterized. Compound 1 possesses a 3D neutral framework with a new (6,6,7)-connected topology based on a single trinuclear cluster, while 2 features a 3D anionic framework with a new (5,6,6,10)-connected topology containing mixed trinuclear and pentanuclear clusters. Remarkably, 1 and 2 show promising photocatalytic activities toward the degradation of rhodamine B and methyl blue, which suggests that different kinds of cluster units may exert different impacts on the decomposition of organic dyes. [ABSTRACT FROM AUTHOR]

Group IVB transition metal (Zr and Hf) dichalcogenide (TMD) monolayers can have higher carrier mobility and higher tunneling current density than group V1B (Mo and W) TMD monolayers. Here we report the synthesis of hexagonal ZrS2 monolayer and few layers on hexagonal boron nitride (BN) using ZrCl4 and S as precursors. The domain size of ZrS2 hexagons is around 1-3 µm. The number of layers of ZrS2 was controlled by tuning the evaporation temperature of ZrCl4. The stacking angle between ZrS2 and BN characterized by transmission electron microscopy shows a preferred stacking angle of near 0°. Field-effect transistors (FETs) fabricated on ZrS2 flakes showed n-type transport behavior with an estimated mobility of 0.1-1.1 cm² V-1 s-1. [ABSTRACT FROM AUTHOR]

A stable porous carbazole-based luminescent metal-organic framework, NENU-522, was successfully constructed. It is extremely stable in air and acidic/basic aqueous solutions, which provides the strategy for luminescent material encapsulation of Ln3+ ions with tunable luminescence for application in light emission. More importantly, Ln3+@NENU-522 can emit white light by encapsulating different molar ratios of Eu3+ and Ln3+ ions. Additionally, Ln3+@NENU-522 is found to be useful as a fluorescent indicator for the qualitative and quantitative detection of nitroaromatic explosives with different numbers of -NO2 groups, and the concentrations of complete quenching are about 2000, 1000, and 80 ppm for nitrobenzene, 1,3-dinitrobenzene, and 2,4,6-trinitrophenol, respectively. Meanwhile, Ln3+@NENU-522 displays high selectivity and recyclability in the detection of nitroaromatic explosives. [ABSTRACT FROM AUTHOR]

In this work, five novel 2D isostructural Cd(II)-lanthanide(III) heterometallic-organic frameworks [CdCl(L)EuxTby(H2O)(DMA)](NO3)·3DMA (IFMC-36-EuxTby: x = 1, y = 0, IFMC-36-Eu; x = 0.6, y = 0.4, IFMC-36-Eu0.6Tb0.4; x = 0.5, y = 0.5, IFMC-36-Eu0.5Tb0.5; x = 0.4, y = 0.6, IFMC-36-Eu0.4Tb0.6; x = 0, y = 1, IFMC-36-Tb; H3L is 4,4',4"-((2,2',2"-(nitrilotris(methylene))tris(1H-benzo[d]imidazole-2,1-diyl))tris(methylene))tribenzoic acid; IFMC = Institute of Functional Material Chemistry) have been successfully synthesized by taking advantage of different molar ratios of lanthanide(III) (Ln(III)) and metalloligands under solvothermal conditions. Further luminescent measurements indicate that IFMC-36-EuxTby exhibits characteristic sharp emission bands of Eu(III) and Tb(III), and the intensities of red and green can be modulated correspondingly by tuning the ratios of Eu(III) and Tb(III). Particularly, the solvent-dependent luminescent behavior of IFMC-36-Eu shows a potential application in detection of small-molecule pollutant nitrobenzene by significant fluorescence quenching. Furthermore, IFMC-36-Eu displays preeminent anti-interference ability and could be used for sensing in the systems with complicated components. This is the first time that a d-f heterometallic-organic framework can be investigated as a chemical sensor for selective, sensitive, and recyclable detection of nitrobenzene. [ABSTRACT FROM AUTHOR]

Amorphous calcium phosphate oftenforms as a precursor phase ina solution at sufficiently high supersaturation and pH, and then transformsto the thermodynamically stable hydroxyapatite. The chemical composition,structure, and property of the amorphous phase are dependent on thestructure of its composing clusters. Based on the results from themeasurements of in situ Ca K-edge X-ray near-edge structure and exsitu X-ray diffraction, as well as the concomitant pH change in thereaction process, here we propose an improved model for the structureof “Posner’s cluster” and identify the threetypes of reactions that lead to the formation of amorphous calciumphosphate and its subsequent transition to crystalline hydroxyapatite. [ABSTRACT FROM AUTHOR]

Theelectrochemical mechanism of the cathode material Li2FeSiO4with reversible extraction/insertion of more thanone Li+from/into the structure has been studied by techniquesof in situ synchrotron X-rayabsorption near edge structure (XANES) and X-ray diffraction (XRD).These advanced techniques provide effective solutions to address thelimitations of characterization by traditional ex situ methods. Thestudy of in situ Fe K-edge XANES indicates that the Fe ion in theLi2FeSiO4is oxidized continuously to high valenceduring the charging process from open circuit potential to 4.8 V,which contributes to the high reversible capacities of the materials.In situ XRD and theoretical study from first-principles calculationshave been employed to reveal the structural evolution of the Li2FeSiO4underlying the high capacity during thecharge/discharge process. The results of both experimental and theoreticalstudies are consistent and indicate that Li2FeSiO4undergoes two two-phase reactions when the electrode is chargedto a high voltage of 4.8 V. [ABSTRACT FROM AUTHOR]

The influence of extending the molecular length of donor-acceptor chromophores on properties relevant to organic optoelectronic devices has been studied by using two new narrow-band-gap systems. Most significantly, we find that the higher molecular weight systems exhibit higher thermal stabilities (beyond 200 °C) when introduced into field effect transistor devices. It is also possible to fabricate bulk heterojunction solar cells using PC61BM with power conversion efficiencies >6%. These high values are not heavily influenced by the blend composition and are achieved without the influence of solvent additives or postdeposition thermal annealing. [ABSTRACT FROM AUTHOR]

We examine the correlations of the dipole moment and conformational stability to the self-assembly and solar cell performance within a series of isomorphic, solution-processable molecules. These charge-transfer chromophores are described by a D1-A-D-A-D1 structure comprising electron-rich 2-hexylbithiophene and 3,3′-di-2-ethylhexylsilylene-2,2′-bithiophene moieties as the donor units D1 and D, respectively. The building blocks 2,1,3-benzothiadiazole (BT) and [1,2,5]thiadiazolo[3,4-c]pyridine (PT) were used as the electron-deficient acceptor units A. Using a combination of UV-visible spectroscopy, field-effect transistors, solar cell devices, grazing incident wide-angle X-ray scattering, and transmission electron microscopy, three PT-containing compounds (1-3) with varying regiochemistry and symmetry, together with the BT-based compound 5,5′-bis{(4-(7-hexylthiophen-2-yl)thiophen-2-yl)-[1,2,5]thiadiazolobenzene}-3,3′-di-2-ethylhexylsilylene-2,2′-bithiophene (4), are compared and contrasted in solution, in thin films, and as blends with the electron acceptor [6,6]-phenyl-C70-butyric acid methyl ester. The molecules with symmetric orientations of the PT acceptor, 1 and 2, yield highly ordered blended thin films. The best films, processed with the solvent additive 1,8-diiodooctane, show donor "crystallite" length scales on the order of 15-35 nm and photovoltaic power conversion efficiencies (PCEs) of 7.0 and 5.6%, respectively. Compound 3, with an unsymmetrical orientation of PT heterocycles, shows subtle differences in the crystallization behavior and a best PCE of 3.2%. In contrast, blends of the BT-containing donor 4 are highly disordered and give PCEs below 0.2%. We speculate that the differences in self-assembly arise from the strong influence of the BT acceptor and its orientation on the net dipole moment and geometric description of the chromophore. [ABSTRACT FROM AUTHOR]

In animals, perfluorinated chemicals (PFCs), specifically perfluorooctanoic acid (PFOA) and perfluorooctane sulfate (PFOS), function as peroxisome proliferator-activated receptor (PPAR) alpha agonists. However, the relevance of animal (primarily rodent) data to humans is unresolved. While plasma adiponectin level is very responsive to PPAR gamma agonist drugs, it has not been determined whether adiponectin level is related to serum PFCs concentrations. In the present study, 287 subjects (12-30 years of age) were recruited to determine the relationship between serum level of PFCs and serum level of adiponectin. The results showed males had higher serum PFOS concentrations than females and that those with metabolic syndrome had lower serum PFOA than controls. Besides, it showed regional elevations of the perfluoroundecanoic acid (PFUA) (median concentration: 7.11 ng/mL) in the study subjects. No relationship of PFOA, PFOS, PFUA, and the sum of all four PFCs was found to glucose homeostasis, adiponectin level, lipid profile, and inflammatory markers. The median and the range of perfluorononanoic acid (PFNA) concentration (in ng/mL; for four categories corresponding to the <50, 50-74, 75-89, and =90th percentiles) were 0.38 (0.38-1.68), 3.22 (1.73-4.65), 5.85 (4.75-8.29), 10.56 (8.40-25.40), respectively. After controlling for confounding factors, multiple linear regression analysis revealed that the mean natural log-transformed level of adiponectin increased significantly across categories of PFNA (in ng/mL; 8.78, 8.73, 9.06, 9.36; P for trend = 0.010 in the full model). In conclusion, higher serum PFNA concentration is associated with elevated serum adiponectin concentration. [ABSTRACT FROM AUTHOR]

In this contribution, we devote our effort to explore the effect of stoichiometry of the 4,4′-dipyridylsulfide (dps) ligand on the final structures in the ZnII-hfipbb binary system (H2hfipbb = 4,4′-(hexafluoroisopropylidene)bis(benzoic acid)). The solvothermal reaction of zinc acetate and H2hfipbb with the different stoichiometries of dps from 0.1 to 0.4 mmol has resulted in three new coordination polymers, [Zn(hfipbb)(H2hfipbb)0.5]n(1) and [Zn2(hfipbb)2(dps)(H2O)]n(2aand 2b). The structure determination reveals that complex 1displays a three-dimensional (3D) 2-fold parallel interpenetrating pillared-layer network with one-dimensional double left- and right-handed helical tubes. Complexes 2aand 2bare framework-isomeric as two unusual (3,4)-connected 3D coordination networks, i.e., a 4-nodal (7·82)(4·7·9)(72·84)(4·72·8·92) net and 2-fold interpenetrating (83)2(85·10) net. In addition, the properties of thermogravimetric analysis, X-ray powder diffraction, and photoluminescent behaviors of the complexes have been also discussed. [ABSTRACT FROM AUTHOR]

An interesting aldehyde- and ketone-induced intermolecular tandem decarboxylation-coupling (Csp3Csp) catalyzed by copper with usc of natural α-amino acids as starting materials is developed under neutral conditions with the production of CO2 and H2O as the only byproducts. Various functionalized nitrogen-containing compounds were obtained by this method. In these processes, interesting regioselecsivites of the alkylation were observed, which has been rationalized by the relative stability of proposed resonance structures based on computation methods. [ABSTRACT FROM AUTHOR]

Bimetallic nanostructures with non-random metal atoms distribution are very important for various applications. To synthesize such structures via benign wet chemistry approach remains challenging. This paper reports a synthesis of a Au/Pd alloy nanostructure through the galvanic replacement reaction between Pd ultrathin nanowires (2.4 ± 0.2 nm in width, over 30 nm in length) and AuCI3 in toluene. Both morphological and structural changes were monitored during the reaction up to 10 h. Continuous changes of chemical composition and crystalline structure from Pd nanowires to Pd68Au32 and Pd45Au55 alloys, and to Au nanopartictes were observed. More interestingly, by using combined techniques such as high-resolution transmission electron microscopy (HRTEM); X-ray diffraction (XRD), energy dispersive X-ray spectrometry (EDS), UV-vis absorption, and extended X-ray absorption fine structure (EXAFS) spectroscopy, we found the formation of Pd68Au32 non-random alloy with Au-rich core and Pd-rich shell, and random Pd45Au55 alloy with uniformly mixed Pd and Au atom inside the nanoparticles, respectively. Density functional theory (DFT) calculations indicated that alkylamine will strongly stabilize Pd to the surface, resulting in diffusion of Au atoms into the core region to form a non-random alloy. We believe such benign synthetic techniques can also enable the large scale preparation of various types of non-random alloys for several technically important catalysis applications. [ABSTRACT FROM AUTHOR]