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2D hybrid lead halide perovskites exhibit versatile photoluminescent behaviors for narrowband to broadband emissions (BBEs) and have become attractive candidates for potential applications such as solid-state lighting. Establishing the relationship between the perovskite structural distortion and BBE is key but challenging in designing and optimizing the perovskite luminophores. Conventional attention is given to analyzing the intra-octahedron distortion of the [PbX

Hepatic ischemia-reperfusion injury (HIRI) is responsible for postoperative liver dysfunction and liver failure. Precise and rapid navigation of HIRI lesions is critical for early warning and timely development of pretreatment plans. Available methods for assaying liver injury fail to provide the exact location of lesions in real time intraoperatively. HIRI is intimately associated with oxidative stress which impairs lysosomal degradative function, leading to significant changes in lysosomal viscosity. Therefore, lysosomal viscosity is a potential biomarker for the precise targeting of HIRI. Hence, we developed a viscosity-activatable second near-infrared window fluorescent probe (NP-V) for the detection of lysosomal viscosity in hepatocytes and mice during HIRI. A reactive oxygen species-malondialdehyde-cathepsin B signaling pathway during HIRI was established. We further conducted high signal-to-background ratio NIR-II fluorescence imaging of HIRI mice. The contour and boundary of liver lesions were delineated, and as such the precise intraoperative resection of the lesion area was implemented. This research demonstrates the potential of NP-V as a dual-functional probe for the elucidation of HIRI pathogenesis and the direct navigation of HIRI lesions in clinical applications.

The stereoselective construction of all-carbon quaternary stereocenters, especially acyclic ones, represents an important challenge in organic synthesis. In particular, homopropargyl amides with a quaternary stereocenter β to a nitrogen atom are valuable synthetic intermediates, which could be transformed to diverse chiral structures through alkyne transformations. However, highly enantioselective synthetic methods for homopropargyl amides with a β quaternary stereocenter are extremely rare. We report here unprecedented substrate-directed, iridium-catalyzed enantioselective hydroalkynylations of trisubstituted alkenes to form an acyclic all-carbon quaternary stereocenter β to a nitrogen atom. The hydroalkynylation of enamide occurred with unconventional selectivity, favoring the more hindered reaction site. Homopropargyl amides with β-stereocenters were prepared in high regio- and enantioselectivities. Combined experimental and computational studies revealed the origin of the regio- and enantioselectivities.

Photocatalytic nitrogen fixation reaction can harvest the solar energy to convert the abundant but inert N2 into NH3. Here, utilizing metal-organic framework (MOF) membranes as the ideal assembly of nanoreactors to disperse and confine gold nanoparticles (AuNPs), we realize the direct plasmonic photocatalytic nitrogen fixation under ambient conditions. Upon visible irradiation, the hot electrons generated on the AuNPs can be directly injected into the N2 molecules adsorbed on Au surfaces. Such N2 molecules can be additionally activated by the strong but evanescently localized surface plasmon resonance field, resulting in a supralinear intensity dependence of the ammonia evolution rate with much higher apparent quantum efficiency and lower apparent activation energy under stronger irradiation. Moreover, the gas-permeable Au@MOF membranes, consisting of numerous interconnected nanoreactors, can ensure the dispersity and stability of AuNPs, further facilitate the mass transfer of N2 molecules and (hydrated) protons, and boost the plasmonic photocatalytic reactions at the designed gas-membrane-solution interface. As a result, an ammonia evolution rate of 18.9 mmol gAu-1 h-1 was achieved under visible light (>400 nm, 100 mW cm-2) with an apparent quantum efficiency of 1.54% at 520 nm.

A rhodium(III)-catalyzed enantioselective C-H activation/annulation process is disclosed. With a catalyst derived from a chiral CpRh(III) complex and a chiral acid, the direct annulation reactions between 1-aryl isoquinoline derivatives and alkynes take place smoothly to afford a series of chiral azoniahelicenes in excellent yields and enantioselectivity (up to 99% yield and 96% ee). Mechanistic studies suggest that C-H bond cleavage may be the turnover-limiting step.

Electrochemistry grants direct access to reactive intermediates (radicals and ions) in a controlled fashion toward selective organic transformations. This feature has been demonstrated in a variety of alkene functionalization reactions, most of which proceed via an anodic oxidation pathway. In this report, we further expand the scope of electrochemistry to the reductive functionalization of alkenes. In particular, the strategic choice of reagents and reaction conditions enabled a radical-polar crossover pathway wherein two distinct electrophiles can be added across an alkene in a highly chemo- and regioselective fashion. Specifically, we used this strategy in the intermolecular carboformylation, anti-Markovnikov hydroalkylation, and carbocarboxylation of alkenes—reactions with rare precedents in the literature—by means of the electroreductive generation of alkyl radical and carbanion intermediates. These reactions employ readily available starting materials (alkyl halides, alkenes, etc.) and simple, transition-metal-free conditions and display broad substrate scope and good tolerance of functional groups. A uniform protocol can be used to achieve all three transformations by simply altering the reaction medium. This development provides a new avenue for constructing Csp(3)−Csp(3) bonds.

The first and asymmetric total synthesis of 4β-acetoxyprobotryane-9β,15α-diol, containing a rare and highly strained trans-fused bicyclo[3.3.0]octane ring system, has been achieved. The synthetically challenging [6-5-5] tricyclic ring system in the final product was efficiently and diastereoselectively synthesized via an asymmetric rhodium-catalyzed [4 + 2] cycloaddition reaction, followed by a unique benzilic acid type rearrangement under very mild conditions. The seven contiguous stereocenters were installed efficiently and diastereoselectively.

Three-dimensional (3D) triply interlocked catenanes are a family of chemical topologies that consist of two identical, mechanically interlocked coordination cage components with intriguingly complex structures. Although only a few successful constructions of 3D interlocked catenanes have been achieved to date via metal-mediated assembly, these complex structures have thus far only been targeted by metal-nitrogen/oxygen coordination techniques. Here, taking advantage of rational ligand design, we report the efficient construction of a series of 3D triply interlocked [2]catenanes of the formula [Ag3L2]2, wherein the metal ions exclusively form bonds to N-heterocyclic carbene (NHC) units, and their subsequent transmetalation to the corresponding [Au3L2]2 gold analogues. The formation and transmetalation reactions proceed under mild conditions and are generally applicable. A series of characterization techniques were applied to confirm the formation and structure of the desired 3D triply interlocked architectures: multinuclear NMR spectroscopy, ESI-MS, and single-crystal X-ray diffraction analysis. The solid-state structure of [Ag3(1a)2]2(PF6)6 unambiguously confirms the existence of a 3D catenane that consists of two identical, mechanically interlocked trinuclear hexacarbene cage components. The interlocking of two 3D cages into a [2]catenane is driven by the efficient π···π stacking of triazine-triazine stacks with cooperative interactions between imidazo[1,5-a]pyridine subunits. Notably, the triply interlocked organometallic cages exhibit good stability toward various organic solvents, concentrations, and temperatures, and no disassembly occurred in the presence of coronene or pyrene. The future construction of mechanically interlocked architectures using metal-carbene bonds rather than metal-nitrogen bonds may provide assemblies with interesting properties for as-yet-unimagined applications in fields such as sensors and molecular electrical conductors.

Chiral nitriles are valuable molecules in modern organic synthesis and drug discovery. Selectively differentiating the two nitrile groups of widely available malononitrile derivatives is a straightforward yet underdeveloped route to construct enantioenriched nitriles. Here we report an enantioselective nickel-catalyzed desymmetrization of malononitriles for the generation of nitrile-containing all-carbon quaternary stereocenters. This protocol involves a nickel-catalyzed addition of aryl boronic acids to alkynes, followed by a selective nitrile insertion, providing unprecedented access to enantioenriched 5-7-membered α-cyano-cycloenones with a fully substituted olefin from a broad range of substrates. The synthetic utility of these nitrile products is demonstrated by gram-scale synthesis and conversion to several useful functional groups.

Achieving multiple cycles of RNA replication within a model protocell would be a critical step toward demonstrating a path from prebiotic chemistry to cellular biology. Any model for early life based on an "RNA world" must account for RNA strand cleavage and hydrolysis, which would degrade primitive genetic information and lead to an accumulation of truncated, phosphate-terminated strands. We show here that cleavage of the phosphodiester backbone is not an end point for RNA replication. Instead, 3'-phosphate-terminated RNA strands can participate in template-directed copying reactions with activated ribonucleotide monomers. These reactions form a pyrophosphate linkage, the stability of which we have characterized in the context of RNA copying chemistry. The presence of free magnesium cations results in cleavage of the pyrophosphate bond within minutes. However, we found that the pyrophosphate bond is relatively stable within an RNA duplex and in the presence of chelated magnesium. We show that, under these conditions, pyrophosphate-linked RNA can act as a template for the polymerization of ribonucleotides into canonical 3'-5' phosphodiester-linked RNA. We suggest that primer extension of 3'-phosphate-terminated RNA followed by template-directed copying represents a plausible nonenzymatic pathway for the salvage and recovery of genetic information following strand cleavage.

Transition-metal-catalyzed enantioselective C-H functionalization has become a powerful strategy for the formation of C-C or C-X bonds, enabling the highly asymmetric synthesis of a wide range of enantioenriched compounds. Atropisomers are widely found in natural products and pharmaceutically relevant molecules, and have also found applications as privileged frameworks for chiral ligands and catalysts. Thus, research into asymmetric routes for the synthesis of atropisomers has garnered great interest in recent years. In this regard, transition-metal-catalyzed enantioselective C-H functionalization has emerged as an atom-economic and efficient strategy toward their synthesis. In this Perspective, the approaches for the synthesis of atropisomers by transition-metal-catalyzed asymmetric C-H functionalization reactions are summarized. The main focus here is on asymmetric catalysis via Pd, Rh, and Ir complexes, which have been the most frequently utilized catalysts among reported enantioselective C-H functionalization reactions. Finally, we discuss limitations on available protocols and give an outlook on possible future avenues of research.

Depression is intimately linked with oxidative stress in the brains. Peroxisome plays vital roles in the regulation of intracellular redox balance by keeping reactive oxygen species (ROS) homeostasis. Available evidence indicates a possible relationship between peroxisomal ROS and depression. Even so, the underlying modulation mechanisms of peroxisomal ROS in depression are still rudimentary due to the limitations of the existing detecting methods. Hence, we developed a two-photon fluorescent probe TCP for the real-time visualization of the first produced ROS superoxide anion radical (O2•-) in peroxisome. Using the two-photon fluorescence imaging, we found that peroxisomal O2•- rose during oxidative stress in the mouse brains, resulting in the inactivation of catalase (CAT). Subsequently, the intracellular H2O2 level elevated, which further oxidized tryptophan hydroxylase-2 (TPH2). Then the decrease contents of TPH2 caused the dysfunction of 5-hydroxytryptamine (5-HT) system in the mouse brains, eventually leading to depression-like behaviors. Our work provides evidence of a peroxisomal O2•- mediated signaling pathway in depression, which will conduce to pinpoint potential targets for the treatment of depression.

Molecular ferroelectrics are becoming an important area of research due to their ability to form a variety of structures exhibiting the desired properties. However, the precise control over the assembly of molecular building blocks for the design and synthesis of photoresponsive molecular ferroelectrics remains a considerable challenge. Here, we report a new hybrid high-temperature ferroelectric, (Me2NH2)[NaFe(CN)5(NO)], by judiciously assembling inorganic photochromic nitroprusside anion, as the framework building block, and polar organic cation Me2NH2+, as the dipole-moment carrier, into the crystal lattice. Ferroelectricity arises through the synergetic ordering of Me2NH2+ below 408 K. Piezoresponse force microscopy witnessed the presence of 180° ferroelectric domains and evidenced polarization switching by repeatedly applying an external electric field. Irradiation of the N-bound nitrosyl ligand (ground state) leads to two different conformations: isonitrosyl O-bound (metastable state I) and side-on nitrosyl conformation (metastable state II). Such photoisomerization realized in solid-state molecular ferroelectrics allows for the photoswitching between the ferroelectric ground state and the metastable state. These results pave the way for new design approaches toward developing next-generation photostimulated ferroelectric materials at the molecular level.

Rhodium(III)-catalyzed enantioselective oxidative C-H/C-H cross-coupling reaction between two arenes is disclosed. With the combination of a chiral CpRh(III) complex and a chiral carboxylic acid additive, the direct coupling reactions between 1-aryl isoquinoline derivatives and electron-rich heteroarenes such as thiophenes, furans, benzothiophenes, and benzofurans are realized via a double C-H functionalization process. A series of axially chiral compounds are obtained in excellent yields and enantioselectivities (up to 99% yield and 99% ee). Mechanistic studies suggest that both C-H bond cleavages may not be the turnover-limiting step.

In the past decades, significant advances have been made on radical Smiles rearrangement. However, the eventually formed radical intermediates in these reactions are limited to the amidyl radical, except for the few examples initiated by a N-centered radical. Here, a novel and practical radical Smiles rearrangement triggered by photoredox-catalyzed regioselective ketyl-ynamide coupling is reported, which represents the first radical Smiles rearrangement of ynamides. This method enables facile access to a variety of valuable 2-benzhydrylindoles with broad substrate scope in generally good yields under mild reaction conditions. In addition, this chemistry can also be extended to the divergent synthesis of versatile 3-benzhydrylisoquinolines through a similar ketyl-ynamide coupling and radical Smiles rearrangement, followed by dehydrogenative oxidation. Moreover, such an ynamide Smiles rearrangement initiated by intermolecular photoredox catalysis via addition of external radical sources is also achieved. By control experiments, the reaction was shown to proceed via key ketyl radical and α-imino carbon radical intermediates.

The abiotic synthesis of ribonucleotides is thought to have been an essential step toward the emergence of the RNA world. However, it is likely that the prebiotic synthesis of ribonucleotides was accompanied by the simultaneous synthesis of arabinonucleotides, 2'-deoxyribonucleotides, and other variations on the canonical nucleotides. In order to understand how relatively homogeneous RNA could have emerged from such complex mixtures, we have examined the properties of arabinonucleotides and 2'-deoxyribonucleotides in nonenzymatic template-directed primer extension reactions. We show that nonenzymatic primer extension with activated arabinonucleotides is much less efficient than with activated ribonucleotides, and furthermore that once an arabinonucleotide is incorporated, continued primer extension is strongly inhibited. As previously shown, 2'-deoxyribonucleotides are also less efficiently incorporated in primer extension reactions, but the difference is more modest. Experiments with mixtures of nucleotides suggest that the coexistence of ribo- and arabinonucleotides does not impede the copying of RNA templates. Moreover, chimeric oligoribonucleotides containing 2'-deoxy- or arabinonucleotides are effective templates for RNA synthesis. We propose that the initial genetic polymers were random sequence chimeric oligonucleotides formed by untemplated polymerization, but that template copying chemistry favored RNA synthesis; multiple rounds of replication may have led to pools of oligomers composed mainly of RNA.

Nonenzymatic RNA primer extension by activated mononucleotides has long served as a model for the study of prebiotic RNA copying. We have recently shown that the rate of primer extension is greatly enhanced by the formation of an imidazolium-bridged dinucleotide between the incoming monomer and a second, downstream activated monomer. However, the rate of primer extension is further enhanced if the downstream monomer is replaced by an activated oligonucleotide. Even an unactivated downstream oligonucleotide provides a modest enhancement in the rate of reaction of a primer with a single activated monomer. Here we study the mechanism of these effects through crystallographic studies of RNA complexes with the recently synthesized nonhydrolyzable substrate analog, guanosine 5'-(4-methylimidazolyl)-phosphonate (ICG). ICG mimics 2-methylimidazole activated guanosine-5'-phosphate (2-MeImpG), a commonly used substrate in nonenzymatic primer extension experiments. We present crystal structures of primer-template complexes with either one or two ICG residues bound downstream of a primer. In both cases, the aryl-phosphonate moiety of the ICG adjacent to the primer is disordered. To investigate the effect of a downstream oligonucleotide, we transcribed a short RNA oligonucleotide with either a 5'-ICG residue, a 5'-phosphate or a 5'-hydroxyl. We then determined crystal structures of primer-template complexes with a bound ICG monomer sandwiched between the primer and each of the three downstream oligonucleotides. Surprisingly, all three oligonucleotides rigidify the ICG monomer conformation and position it for attack by the primer 3'-hydroxyl. Furthermore, when GpppG, an analog of the imidazolium-bridged intermediate, is sandwiched between an upstream primer and a downstream helper oligonucleotide, or covalently linked to the 5'-end of the downstream oligonucleotide, the complex is better preorganized for primer extension than in the absence of a downstream oligonucleotide. Our results suggest that a downstream helper oligonucleotide contributes to the catalysis of primer extension by favoring a reactive conformation of the primer-template-intermediate complex.

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-aryl-substituted 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 additio...

Specific cell adhesion and osteogenicity are both crucial factors for the long-term success of titanium implants. In this work, two mussel-derived bioactive peptides were designed to one-step dual-biofunctionalization of titanium implants via robust catechol/TiO2 coordinative interactions. The highly biomimetic peptides capped with integrin-targeted sequence or osteogenic growth sequence could efficiently improve the biocompatibilities of titanium implants and endow the implants with abilities to induce specific cell adhesion and enhanced osteogenicity. More importantly, rationally combined use of the two biomimetic peptides indicated an enhanced synergism on osteogenicity, osseointegration and finally the mechanical stability of Ti implants in vivo. Therefore, the highly biomimetic mussel-derived peptides and the dual-functional strategy in this study would provide a facile, safe, and effective means for improving clinical outcome of titanium-based medical implants.

The control of chemo-, regio-, diastereo-, and enantioselectivity is a central theme in organic synthesis. The capability to obtain the full set of stereoisomers of a molecule would significantly enhance the efficiency for the synthesis of natural product analogues and creation of chiral compound libraries for drug discovery. Despite the tremendous progress achieved in the field of asymmetric synthesis in the past decades, the precise control of both relative and absolute configurations in catalyst-controlled reactions that create multiple stereocenters remains a significant synthetic challenge. We report here the development of a catalyst-controlled hydroboration with hitherto unattainable selectivity. The Rh-catalyzed hydroboration of α, β-unsaturated carbonyl compounds with pinacolborane proceeds with high levels of regio-, diastereo-, and enantioselectivities to provide a hydroboration product with two vicinal stereocenters. Through the appropriate choice of substrate geometry ( E or Z) and ligand enantiomer ( S or R), all the possible diastereoisomers are readily accessible. The boron-containing products underwent many stereospecific transformations, thus providing a strategy for collective stereodivergent synthesis of diverse valuable chiral building blocks.

Oxidative stress in depression is a prime cause of neurotransmitter metabolism dysfunction in the brain. Acetylcholinesterase (AChE), a key hydrolase in the cholinergic system, directly determines the degradation of neurotransmitters. However, due to the complexity of the brain and lack of appropriate in situ imaging tools, the mechanism underlying the changes in AChE activity in depression remains unclear. Hence, we generated a two-photon fluorescence probe (MCYN) for real-time visualization of AChE with excellent sensitivity and selectivity. AChE can specifically recognize and cleave the carbamic acid ester bond in MCYN, and MCYN emits bright fluorescence at 560 nm by two-photon excitation at 800 nm. By utilizing MCYN to monitor AChE, we discovered a significant increase in AChE activity in the brains of mice with depression phenotypes. Notably, with the assistance of a two-photon fluorescence imaging probe of the superoxide anion radical (O2•–), in vivo visualization for the first time revealed the pos...

Cyclodehydrogenation is a versatile reaction that has enabled the syntheses of numerous polycyclic aromatic hydrocarbons (PAHs). We now describe a unique Scholl reaction of 6,7,13,14-tetraarylbenzo[k]tetraphene, which "unexpectedly" forms five-membered rings accompanying highly selective 1,2-shift of aryl groups. The geometric and optoelectronic nature of the resulting bistetracene analogue with five-membered rings is comprehensively investigated by single-crystal X-ray, NMR, UV-vis absorption, and cyclic voltammetry analyses. Furthermore, a possible mechanism is proposed to account for the selective five-membered-ring formation with the rearrangement of the aryl groups, which can be rationalized by density functional theory (DFT) calculations. The theoretical results suggest that the formation of the bistetracene analogue with five-membered rings is kinetically controlled while an "expected" product with six-membered rings is thermodynamically more favored. These experimental and theoretical results provide further insights into the still controversial mechanism of the Scholl reaction as well as open up an unprecedented entry to extend the variety of PAHs by programing otherwise unpredictable rearrangements during the Scholl reaction.

We report the synthesis of guanosine 5'-(4-methylimidazolyl)phosphonate (ICG), the third member of a series of nonhydrolyzable nucleoside 5'-phosphoro-2-methylimidazolide (2-MeImpN) analogues designed for mechanistic studies of nonenzymatic RNA primer extension. The addition of a 2-MeImpN monomer to a primer is catalyzed by the presence of a downstream activated monomer, yet the three nonhydrolyzable analogues do not show catalytic effects under standard mildly basic primer extension conditions. Surprisingly, ICG, which has a pKa similar to that of 2-MeImpG, is a modest catalyst of nonenzymatic primer extension at acidic pH. Here we show that ICG reacts with 2-MeImpC to form a stable 5'-5'-imidazole-bridged guanosine-cytosine dinucleotide, with both a labile nitrogen-phosphorus and a stable carbon-phosphorus linkage flanking the central imidazole bridge. Cognate RNA primer-template complexes react with this GC-dinucleotide by attack of the primer 3'-hydroxyl on the activated N-P side of the 5'-5'-imidazole bridge. These observations support the hypothesis that 5'-5'-imidazole-bridged dinucleotides can bind to cognate RNA primer-template duplexes and adopt appropriate conformations for subsequent phosphodiester bond formation, consistent with our recent mechanistic proposal that the formation of activated 5'-5'-imidazolium-bridged dinucleotides is responsible for 2-MeImpN-driven primer extension.

The nonenzymatic replication of primordial RNA is thought to have been a critical step in the origin of life. However, despite decades of effort, the poor rate and fidelity of model template copying reactions have thus far prevented an experimental demonstration of nonenzymatic RNA replication. The overall rate and fidelity of template copying depend, in part, on the affinity of free ribonucleotides to the RNA primer–template complex. We have now used 1H NMR spectroscopy to directly measure the thermodynamic association constants, Kas, of the standard ribonucleotide monophosphates (rNMPs) to native RNA primer–template complexes. The binding affinities of rNMPs to duplexes with a complementary single-nucleotide overhang follow the order C > G > A > U. Notably, these monomers bind more strongly to RNA primer–template complexes than to the analogous DNA complexes. The relative binding affinities of the rNMPs for complementary RNA primer–template complexes are in good quantitative agreement with the predictions of a nearest-neighbor analysis. With respect to G:U wobble base-pairing, we find that the binding of rGMP to a primer–template complex with a 5′-U overhang is approximately 10-fold weaker than to the complementary 5′-C overhang. We also find that the binding of rGMP is only about 2-fold weaker than the binding of rAMP to 5′-U, consistent with the poor fidelity observed in the nonenzymatic copying of U residues in RNA templates. The accurate Ka measurements for ribonucleotides obtained in this study will be useful for designing higher fidelity, more effective RNA replication systems.

A novel copper-catalyzed arylation of benzylic C–H bonds with nucleophilic arylboronic acids has been developed that provides an efficient way to synthesize various 1,1-diarylalkanes with a broad substrate scope and excellent functional group compatibility. The reactions occur at room temperature using alkylarenes as the limiting reagents, which allows access to the arylation of the more valuable and complex bioactive compounds.

Recent advances in bottom-up synthesis of atomically defined graphene nanoribbons (GNRs) with various microstructures and properties have demonstrated their promise in electronic and optoelectronic devices. Here we synthesized N = 9 armchair graphene nanoribbons (9-AGNRs) with a low optical band gap of ∼1.0 eV and extended absorption into the infrared range by an efficient chemical vapor deposition process. Time-resolved terahertz spectroscopy was employed to characterize the photoconductivity in 9-AGNRs and revealed their high intrinsic charge-carrier mobility of approximately 350 cm2·V-1·s-1.

Ruthenium is a promising low-temperature catalyst for Fischer–Tropsch synthesis (FTS). However, its scarcity and modest specific activity limit its widespread industrialization. We demonstrate here a strategy for tuning the crystal phase of catalysts to expose denser and active sites for a higher mass-specific activity. Density functional theory calculations show that upon CO dissociation there are a number of open facets with modest barrier available on the face-centered cubic (fcc) Ru but only a few step edges with a lower barrier on conventional hexagonal-closest packed (hcp) Ru. Guided by theoretical calculations, water-dispersible fcc Ru catalysts containing abundant open facets were synthesized and showed an unprecedented mass-specific activity in the aqueous-phase FTS, 37.8 molCO·molRu–1·h–1 at 433 K. The mass-specific activity of the fcc Ru catalysts with an average size of 6.8 nm is about three times larger than the previous best hcp catalyst with a smaller size of 1.9 nm and a higher specific su...

Overgeneration of reactive oxygen species (ROS) is closely associated with cellular damage and diseases. As superoxide anion (O2(•-)) is the precursor of other ROS, exploring O2(•-) fluctuations in cells and in vivo is of great significance. To address this critical need, we have developed a novel reversible fluorescent probe with one-photon and two-photon fluorescence properties, which is well suited for monitoring O2(•-) fluxes selectively and dynamically. Imaging results substantiate dynamic and reversible fluorescence responses of this probe to intracellular O2(•-) under apoptotic stimuli. Moreover, this probe can conveniently visualize changes in O2(•-) concentration during reperfusion injury in hepatocytes, zebrafish, and mice, by means of one-photon or two-photon imaging according to depths of various samples. The present study provides a powerful fluorescent imaging tool for dynamic tracking of O2(•-) in live cells and in vivo.

Active center engineering at atomic level is a grand challenge for catalyst design and optimization in many industrial catalytic processes. Exploring new strategies to delicately tailor the structures of active centers and bonding modes of surface reactive intermediates for nanocatalysts is crucial to high-efficiency nanocatalysis that bridges heterogeneous and homogeneous catalysis. Here we demonstrate a robust approach to tune the CO oxidation activity over CeO2 nanowires (NWs) through the modulation of the local structure and surface state around Ln(Ce)' defect centers by doping other lanthanides (Ln), based on the continuous variation ;of the ionic radius of lanthanide dopants caused by the lanthanide contraction. Homogeneously doped (110)-oriented CeO2:Ln NWs with no residual capping agents were synthesized by controlling the redox chemistry of Ce(III)/Ce(IV) in a mild hydrothermal process. The CO oxidation reactivity over CeO2:Ln NWs was dependent on the Ln dopants, and the reactivity reached the maximum in turnover rates over Nd-doped samples. On the basis of the results obtained from combined experimentations and density functional theory simulations, the decisive factors of the modulation effect along the lanthanide dopant series were deduced as surface oxygen release capability and the bonding configuration of the surface adsorbed species (i.e., carbonates and bicarbonates) formed during catalytic process, which resulted in the existence of an optimal doping effect from the lanthanide with moderate ionic radius.

Synthesis of diverse two-dimensional nanostructures with unique material properties is of current interest and multidisciplinary importance but remains a challenge for trivalent rare earth (RE)-selenium (Se) compounds because of the weak affinity between hard rare earth cations and soft selenium anions. In this article, for the first time, we report a mild solution approach toward a series of two-dimensional trivalent RE-selenium compound nanocrystals, namely RESe2 nanosheets (RE = La to Nd, for EuSe2, nanobars were obtained) and RE4O4Se3 nanoplates (RE = Nd, Sm, Gd to Ho), under a high chemical potential of selenium obtained by activating SeO2 powder with oleylamine in high boiling point organic solvents. Both kinds of nanocrystals contain Se with -1 valence in planar Se layers, allowing for a great variability in their crystal structures. Satellite diffraction peaks were observed in the electron diffraction pattern of LaSe2 nanosheets, indicating the presence of Peierls distortion in the Se layers. In the RE4O4Se3 nanoplates, the interaction between Se(2-) ions and [Se-Se](2-) dumbbells in the Se layers increases when the radii of the RE(3+) ions decrease along the lanthanide series, resulting in a narrower optical band gap (from 1.96 to 1.73 eV). The LaSe2 nanosheet films fabricated by drop-casting exhibited good electrical conductivity at room temperature (about 1 Ω·cm(-1)). Further, the RE4O4Se3 nanoplates showed very high light extinction capacity in the visible region (extinction coefficient μi: 4.4 × 10(5) cm(-1) for Nd4O4Se3, and 3.1 × 10(5) cm(-1) for Gd4O4Se3), comparable to that (5 × 10(5) cm(-1)) of CuInS2 commonly used in solar cells.

A tandem demethylation-aryl borylation strategy was developed to synthesize OBO-doped tetrabenzo[a,f,j,o]perylenes (namely “bistetracenes”) and tetrabenzo[bc,ef,kl,no]coronenes (namely “peritetracenes”). The OBO-doped bistetracene analogues exhibited excellent stability and strong fluorescence, in contrast to the unstable all-carbon bistetracene. Single-crystal X-ray analysis for OBO-doped bistetracene revealed a twisted double [5]helicene structure, indicating that this synthesis is applicable to new heterohelicenes. Importantly, cyclodehydrogenation of the bistetracene analogues successfully produced the unprecedented heteroatom-doped peritetracenes, which opened up a new avenue to periacene-type nanographenes with stable zigzag edges.

In this article, we present a chemoaffinity-mediated synthetic strategy toward trivalent rare earth (RE) sulfides-based nanocrystals with poor affinity between cation and anion (i.e., RE(3+) and S(2-)). With the affinity mediation among multiple constituents based on hard and soft acid and base theory, we synthesized a series of monodisperse NaRES(2) nanocrystals (RE = La to Lu, Y). The revelation of the nanocrystal growth mechanism from both experimental evidence and crystal structure modeling has enabled a robust control over the sizes and morphologies of the nanocrystals. This principle of chemoaffinity has also promised the synthesis of well-defined but even more complex RE-based hetero-nanostructures (i.e. NaLaS(2)-Au, Au@NaLaS(2), NaLaS(2)@Ag(2)S, Au@NaLaS(2)@Ag(2)S) with tunable optical properties. Furthermore, this synthetic method has yielded durable NaCeS(2)-based red nano-pigments under ambient conditions, with superior brightness and permeability in polydimethylsiloxane.

Molecular motion is one of the structural foundations for the development of functional molecular materials such as artificial motors and molecular ferroelectrics. Herein, we show that pendulum-like motion of the terminal group of a molecule causes a ferroelectric phase transition. Complex 4-methoxyanilinium tetrafluoroborate-18-crown-6 ([C(7)H(10)NO(18-crown-6)](+)[BF(4)](-), 1) shows a second-order ferroelectric phase transition at 127 K, together with an abrupt dielectric anomaly, Debye-type relaxation behavior, and the symmetry breaking confirmed by temperature dependence of second harmonic generation effect. The origin of the polarization is due to the order-disorder transition of the pendulum-like motions of the terminal para-methyl group of the 4-methoxyanilinium guest cation; that is, the freezing of pendulum motion at low temperature forces significant orientational motions of the guest molecules and thus induces the formation of the ferroelectric phase. The supramolecular bola-like ferroelectric is distinct from the precedent ferroelectrics and will open a new avenue for the design of polar functional materials.