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The water-splitting reaction using photocatalyst particles is a promising route for solar fuel production1–4. Photo-induced charge transfer from a photocatalyst to catalytic surface sites is key in ensuring photocatalytic efficiency5; however, it is challenging to understand this process, which spans a wide spatiotemporal range from nanometres to micrometres and from femtoseconds to seconds6–8. Although the steady-state charge distribution on single photocatalyst particles has been mapped by microscopic techniques9–11, and the charge transfer dynamics in photocatalyst aggregations have been revealed by time-resolved spectroscopy12,13, spatiotemporally evolving charge transfer processes in single photocatalyst particles cannot be tracked, and their exact mechanism is unknown. Here we perform spatiotemporally resolved surface photovoltage measurements on cuprous oxide photocatalyst particles to map holistic charge transfer processes on the femtosecond to second timescale at the single-particle level. We find that photogenerated electrons are transferred to the catalytic surface quasi-ballistically through inter-facet hot electron transfer on a subpicosecond timescale, whereas photogenerated holes are transferred to a spatially separated surface and stabilized through selective trapping on a microsecond timescale. We demonstrate that these ultrafast-hot-electron-transfer and anisotropic-trapping regimes, which challenge the classical perception of a drift–diffusion model, contribute to the efficient charge separation in photocatalysis and improve photocatalytic performance. We anticipate that our findings will be used to illustrate the universality of other photoelectronic devices and facilitate the rational design of photocatalysts.

Te doping modifies the absorption and emission spectra of pristine Cs2ZrCl6, thus introducing new absorption channels, reducing the excitation energy and achieving high luminous efficiency.

In the need for improving the labeling quality of super-resolution imaging, multifarious fluorescent labeling strategies have sprang up. Among them, a small molecule inhibitor-probe (SMI-probe) shows its advancement in fine mapping due to its smaller size and its specific binding to a specific site. Herein, we report a novel protocol of mechanism-guided directional modification of fluorophores into fluorescent inhibitors for enzyme targeting, which could half the size of the SMI-probe. To confirm the feasibility of the strategy, carboxylesterase (hCE) inhibitors are designed and developed. Among the constructed molecule candidates, NIC-4 inhibited both isoforms of hCE1 and hCE2, with IC50values of 4.56 and 4.11 μM. The CE-targeting specificity of NIC-4 was confirmed by colocalizing with an immunofluorescent probe in fixed-cell confocal imaging. Moreover, NIC-4 was used in live-cell super-resolution microscopy, which indicates dotlike structures instead of the larger staining with the immunofluorescent probe. Moreover, it enables the real-time tracking of dynamic flow of carboxylesterases in live cells.

Quasi-two-dimensional hybrid perovskites have proved to be promising next-generation semiconductor materials for light-emitting diodes and photovoltaic applications. However, these materials usually contain a mixture of phases that their photoluminescence is not monochrome. Here, we synthesize a series of quasi-two-dimensional organic–inorganic hybrid perovskite nanosheets (NSs) with the triplet energy acceptor molecule naphthalene methylamine (NMA), that is, (NMA)2(MA)⟨n⟩–1Pb⟨n⟩Br3⟨n⟩+1(NMA = C11H9NH3, ⟨n⟩ = 2,3,4). It was found that with the organic layer, the light color of the NSs is pure green on account of energy transfer from the inorganic layer whose band gap is beyond triplet states of NMA (∼2.6 eV). Also, we demonstrated that the triplet energy transfer lifetime is ∼7 ps for the ⟨n⟩ = 2 and ∼9 ps for the ⟨n⟩ = 3 quasi-two-dimensional hybrid perovskite NSs by spectroscopy.

Inkless printing based on rewritable papers has recently made great progress because it can improve the utilization rate of papers, which is of great significance for saving resources and protecting the environment. Among them, light-responsive rewritable papers (LRPs) are a hot research topic because light is clean, easily available, wavelength and intensity adjustable, and noncontacting. However, the photochromic material, as the imaging substance of LRPs, is easily affected by environmental conditions, resulting in insufficient time to read the information. In view of this, we designed and constructed an acid/base tunable diarylethene molecular system that can effectively adjust the photochromic properties by reversibly changing the electron density of the diarylethene photoreaction center through protonation and demonstrated its potential as an imaging material with a longer legible time. What makes us more satisfied is that the acidification can not only extend the legible time of carrying information but also bring a clear and stable absorption/fluorescence imaging dual mode, which can better reflect details and improve contrast. Therefore, we believe that this tunable photochromic diarylethene molecule is a potential imaging material for the development of new LRPs.

Lead-free halide double perovskites (DPs) have been considered to be an effective alternative for solving the problem of lead perovskite toxicity and instability. We report a series of lead-free halide DP single crystals (SCs) and nanocrystals (NCs) (Cs2AgxNa1–xFeCl6(0 ≤ x≤ 1)). The alloying strategy not only effectively regulates the optical band gap but also significantly improves the air stability and thermal stability. The absorption edge of the NCs is slightly blue-shifted compared to that of the corresponding SCs. Excitingly, we find that Fe3+ions can be successfully doped into chloride DPs Cs2M′MCl6(M′ = Na or Ag; M = In, Sb or Bi) and cause the band gap to effectively decrease with universality. In addition, the effect of crystal size on stability is further studied. This work not only explore a series of lead-free transition-metal DPs but also brings about more possibilities for optoelectronic applications in lead-free perovskites.

Lead-free double perovskite nanocrystals (NCs), such as Cs2AgInCl6, have attracted considerable attention as stable and non-toxic alternatives to lead-based perovskites. However, the low photoluminescence (PL) intensity of pristine Cs2AgInCl6limits its practical applications. In this study, a series of Cs2AgIn1−γ−xBixLaγCl6NCs were synthesized to break the parity-forbidden transition and modify the associated optical functionalities. A broadband bright warm-white emission in the visible region was achieved, with an excellent PL quantum yield of 60%. The dynamic mechanism, involving ultrafast transient absorption, suggests that high-efficiency PL is induced by triplet self-trapping exciton emission. The incorporation of La3+-Bi3+facilitated the singlet-triplet transition by increasing the lifetime and quickening the intersystem crossing process. This finding provides a reliable method for optimizing the optical properties of emerging lead-free halide perovskite NCs.

The biological roles of reactive oxygen species (ROS) depend highly on their dynamics. However, it has been challenging for measuring the dynamics of ROS in cells. In this study, we address a core challenge in developing fluorescence probes for monitoring ROS dynamics by designing a redox couple that can respond rapidly to both oxidation and reduction events. We show that such molecules can be designed by taking advantage of the steric effects of electron-donating groups at the ortho position relative to the selenium center. We demonstrate this design in a new fluorescence probe named Fl-Se. Results reveal that Fl-Se and its oxidized product Fl-SeO rapidly respond to HClO, an important member of the ROS family, and glutathione (GSH), with t1/2= 2.7 ms at [HClO] = 1 μM; t1/2= 61 ms at [GSH] = 1 mM. When applied in cells, Fl-Se satisfactorily tracks the dynamics of intracellular HClO in H2O2-stimulated HL-60 cells, as well as the different dynamic behaviors of HClO fluctuations involved in the phorbol 12-myristate-13-acetate-activated immune response of RAW264.7 cells and the 3-deazaneplanocin A-induced apoptosis of HL 60 cells.

Lead-free halide perovskite nanocrystals (NCs) have recently attracted attention due to their nontoxicity and stability as alternatives to lead-based perovskite NCs. Here, we report undoped and manganese-doped all-inorganic, lead-free double perovskite (DP) NCs: Cs2NaInxBi1–xCl6(0 < x< 1) and Cs2NaInxBi1–xCl6:Mn (0 ≤ x≤ 1) NCs. Undoped NCs exhibit blue emission. Through doping Mn2+ions into Cs2NaInxBi1–xCl6NCs, we can avoid self-trapped exciton emission and realize bright orange red emission of Mn2+dopants with the highest photoluminescence quantum efficiency of 44.6%. The photoluminescence (PL) is tunable from yellow emission to orange-red emission corresponding to a red shift from 583 to 614 nm with increasing In content. Interestingly, the PL emission of Mn-doped NCs shows a red shift from the bulk size to the nanoscale. The Mn-doped NCs show good stability in air. In addition, we further prove the process of dark self-trapped state-assisted Mn2+emission in DP NCs by ultrafast transient absorption techniques.

A thorough investigation of the initial decomposition pathways of triazoles and their nitro-substituted derivatives has been conducted using the MP2 method for optimization and DLPNO-CCSD(T) method for energy. Different initial thermolysis mechanisms are proposed for 1,2,4-triazole and 1,2,3-triazole, the two kinds of triazoles. The higher energy barrier of the primary decomposition path of 1,2,4-triazole (H-transfer path, ∼52 kcal/mol) compared with that of 1,2,3-triazole (ring-open path, ∼45 kcal/mol) shows that 1,2,4-triazole is more stable, consistent with experimental observations. For nitro-substituted triazoles, more dissociation channels associated with the nitro group have been obtained and found to be competitive with the primary decomposition paths of the triazole skeleton in some cases. Besides, the effect of the nitro group on the decomposition pattern of the triazole skeleton has been explored, and it has been found that the electron-withdrawing nitro group has an opposite effect on the primary dissociation channels of 1,2,4-triazole derivatives and 1,2,3-triazole derivatives.

Lead halide perovskite nanocrystals (NCs) have been widely studied for application in optoelectronic devices due to their excellent optical properties and low-cost synthesis. However, the toxicity of lead and the poor stability of the NCs hindered their practical applications. Sn2+-based perovskite with low toxicity was first developed; however, the Sn2+-based perovskite NCs are unstable in air and oxidize easily. Recently, air-stable lead-free perovskite NCs have been developed and received increasing attention. Unfortunately, the optical and optoelectronic properties of these lead-free halide perovskite NCs are generally far worse than those of lead-perovskite NCs.

Lead-free halide double perovskites have gathered wide scientific interest since they are environmentally friendly and stable. However, compared to the lead perovskites, their optoelectronic properties are compromised. Herein we report a series of bulk lead-free mixed Bi-In halide double perovskites: Cs2AgBi1−xInxCl6(0

Heterovalent-metal doping is an efficient tool to tune the optoelectronic properties of the famous halide perovskites. Previous studies have focused on the heterovalent-doping in three-dimensional (3D) halide perovskites. However, there is a lack of such doping in two-dimensional perovskites which possess unique optoelectronic properties and improved chemical stability as compared to 3D analogues. Here, we present successful doping of Bismuth into the lattice of lead-free, two-dimensional perovskite PEA2SnBr4single crystals. Structural characterizations demonstrate that the doped crystals possess identical crystal structure and layered morphology with the pristine one. Intriguingly, we find the PL peak and spectral shape can be tailored by tuning the concentration of Bi dopants. Femtosecond transient absorption spectroscopy is performed to understand the underlying mechanism related to tunable PL behaviors, and a clear picture of the Bismuth-doping impact is provided.

Vacancy-ordered lead-free perovskites with more-stable crystalline structures have been intensively explored as the alternatives for resolving the toxic and long-term stability issues of lead halide perovskites (LHPs). The dispersive energy bands produced by the closely packed halide octahedral sublattice in these perovskites are meanwhile anticipated to facility the mobility of charge carriers. However, these perovskites suffer from unexpectedly poor charge carrier transport. To tackle this issue, we have employed the ultrafast, elemental-specific X-ray transient absorption (XTA) spectroscopy to directly probe the photoexcited electronic and structural dynamics of a prototypical vacancy-ordered lead-free perovskite (Cs3Bi2Br9). We have discovered that the photogenerated holes quickly self-trapped at Br centers, simultaneously distorting the local lattice structure, likely forming small polarons in the configuration of Vkcenter (Br2–dimer). More significantly, we have found a surprisingly long-lived, structural distorted state with a lifetime of ∼59 μs, which is ∼3 orders of magnitude slower than that of the charge carrier recombination. Such long-lived structural distortion may produce a transient “background” under continuous light illumination, influencing the charge carrier transport along the lattice framework.

Photochromic diarylethenes have been widely used in many fields. However, their cyclization process must be induced by UV light. In this article, a simple strategy is developed by extending π-conjugation with electron donating groups. The modified dirylethene derivative can photocyclolize under 405-nm light with a good photochromic efficiency. Meanwhile, its absorption and moderate fluorescence can be switched effectively in both directions by visible lights (405 and 520 nm, respectively) in different solutions and in living cells. We believe that this simple method will become a versatile strategy for developing various dirylethylenes with visible-light photochromism.

Reactive force field (Reaxff) is a powerful method, which employs bond order/bond length formulism to describe bond breaking and bond reformation. In this work, a modification to the bond order formula was made and Reaxff parameters were re-optimized. The underlying idea of these modifications is to improve the energy gradient. Better agreements of the bond dissociation potential curves with the quantum mechanical curves were obtained on the basis of the aforementioned changes. Reaxff simulation was carried out to gain the understandings of the iso-octane pyrolysis. The apparent rate constants obtained using the newly optimized parameters fit well with the experimental results. The simulation results are in agreement with the existing experimental results. A maximum of C2hydrocarbons were found to have the largest percentage. The distribution of the iso-octane decomposition pathway was illustrated.

The rapid detection of chemical explosives is crucial for national security and public safety, and the investigation of sensing mechanisms is important for designing highly efficient chemosensors. This study theoretically investigates the detection and fluorescence mechanism of a newly synthesized pyrene-based chemosensor for the detection of trinitrotoluene (TNT) through density-functional-theory (DFT) and time-dependent density-functional-theory (TDDFT) methods and suggests a different interaction product of the probe and TNT from previously reported ones [Mosca et al. J. Am. Chem. Soc.2015, 137, 7967]. Instead of forming Meisenheimer complexes, the energies of which are beyond those of the reactants, a low-energy product generated by a π–π-stacking interaction is more rational and favorable. The fluorescence-quenching property further confirms that the π–π-stacking product is the predicted one rather than luminescent Meisenheimer complexes. Frontier-molecular-orbital (FMO)-analysis results show that photoinduced electron transfer (PET) is the mechanism underlying the luminescence quenching of the probe upon exposure to TNT.

Achieving high-efficiency tunable emission in a single phosphor remains a significant challenge. Herein, we report a series of Sb3+-doped all-inorganic double perovskites, Sb3+:Cs2NaScCl6, with efficient excitation-dependent emission. In 0.5%Sb3+:Cs2NaScCl6, strong blue emission with a high photoluminescence quantum yield (PLQY) of 85% is obtained under 265 nm light irradiation, which turns into bright neutral white light with a PLQY of 56% when excited at 303 nm. Spectroscopic and computational investigations were performed to reveal the mechanism of this excitation-dependent emission. Sb3+doping induces two different excitation channels: the internal transition of Sb3+: 5s2→ 5s5p and the electron transfer transition of Sb3+: 5s → Sc3+3d. The former one generates excited Sb3+ions, which can undergo efficient energy transfer to populate the host self-trapped exciton (STE) state, yielding enhanced blue emission. The latter one leads to the formation of a new STE state with the hole localized on Sb3+and the electron delocalized on the nearest Sc3+, which accounts for the newly exhibited low-energy emission. The difference in the excitation pathways of the two emitting STE states results in the highly efficient excitation-dependent emission, making the doped systems promising anticounterfeiting materials.

We used a combined quantum mechanical/mechanical molecular (QM/MM) method to investigate ionization and electron attachment for nucleobases in water. We first explored the snapshot number and QM-region size to get converged results. The computations of 20 snapshots can get converged physical quantities and converged QM regions contain about 100 atoms. We computed the vertical ionization energies (VIEs), adiabatic ionization energies, vertical electron affinities, adiabatic electron affinities, and vertical detachment energies of five bases in the explicit aqueous solvent. The computational VIEs of cytosine and thymine agree well with the experimental values in aqueous solutions. The results of the five physical quantities indicate that the QM-region polarization by bulk water evidently affects the ionization and electron attachment. Holes or excess electrons do not entirely localize on nucleobases in the ionization and electron attachment. The QM-region polarization and the movements of the QM atoms induce a drastic decrease (∼2.1 eV for cation and ∼2.9 eV for anion) of the cationic and anionic energies in structural relaxations. The potential energy surfaces of the cation and anion would become very steep near the equilibrium structure.

Lead-free double-perovskite nanocrystals (NCs), that is, Cs2AgInxBi1–xCl6(x= 0, 0.25, 0.5, 0.75, and 0.9), that can be tuned from indirect band gap (x= 0, 0.25, and 0.5) to direct band gap (x= 0.75 and 0.9) are designed. Direct band gap NCs exhibit 3 times greater absorption cross section, lower sub-band gap trap states, and >5 times photoluminescence quantum efficiency (PLQE) compared to those observed for indirect band gap NCs (Cs2AgBiCl6). A PLQE of 36.6% for direct band gap NCs is comparable to those observed for lead perovskite NCs in the violet region. Besides the band edge violet emission, the direct band gap NCs exhibit bright orange (570 nm) emission. Density functional theory calculations suggesting forbidden transition is responsible for the orange emission, which is supported by time-resolved PL and PL excitation spectra. The successful design of lead-free direct band gap perovskite NCs with superior optical properties opens the door for high-performance lead-free perovskite optoelectronic devices.

Artificial photosynthetic systems consisted of nanocrystal light absorbers, molecular redox mediators, and catalysts are one of the most promising and flexible approaches for solar fuel generation because their constituents can be independently tuned. In this work, we investigate the photoreduction of three viologen derivatives, one of the most widely investigated molecular redox mediators, of different redox potentials, 7,8-dihydro-6H-dipyrido[1,2-a:2′,1′-c][1,4]diazepinediium (PDQ2+), methyl viologen (MV2+), and benzyl viologen (BV2+), using CdS quantum dots (QDs) as the light absorber and mercaptopropionic acid as a sacrificial electron donor in aqueous (pH = 7) solution. Under continuous 405 nm light-emitting diode illumination, the steady-state radical generation quantum yield (QY) follows the order of PDQ•+(15.99%) > MV•+(12.61%) > BV•+(6.56%). Transient absorption spectroscopy studies show that while the rates of initial electron transfer (ET) from the excited QD conduction band to the mediators, following the order of BV2+> MV2+> PDQ2+, decrease for mediators with more negative redox potentials (and lower ET driving force), the initial transient charge separation QYs are unity in all samples because these ET rates are much faster than the intrinsic exciton decay within the QD. The steady-state QYs are much smaller than unity because of charge recombination (CR), whose rates, following the order of BV2+> MV2+> PDQ2+, decrease for mediators with more negative redox potentials (and higher ET driving force in the Marcus’ inverted regime). In these systems, there exists a long-lived component in the radial decay kinetics, whose amplitudes determine the steady-state radical generation QYs. We speculate that the desorption of the radical from the QD surface is essential for the suppression of CR and is responsible for the steady-state generation of radicals. This work provides new insight for rational design and improvement of efficient QD/redox mediator-based photoreduction systems.

In this study, we examined the reaction between the resonant i-C4H3radical and C2H2. A reaction network was constructed using CCSD(T)/CBS//M06-2X/6-311++G(d,p) dual level theory. Several undisclosed reaction channels were first examined. Their necessities were demonstrated by the branching ratios. The reaction network shows that hydrogen elimination reaction products, carbon–carbon bond-breaking reaction products, four-membered rings, or six-membered rings may be possible products. To further examine which products are more preferred under different conditions, one combined master equation was solved by including all interconnected reaction channels with temperature in the range of 600 and 2100 K at 100 K intervals under three pressures, 30 Torr and 1 and 10 atm. The branching ratio shows in particular that aromatic products, including phenyl and o-benzyne, are not the most preferable products under all of the conditions studied. 3- Hexene-1,5-diyne, 1,1-diethynylethene, etc. may also be produced under different temperatures at each pressure. This work also shows that carbon–carbon bond-breaking reaction products can be generated with an appreciable fraction under some conditions. Finally, important reaction channels and their modified Arrhenius parameters leading to the preferable products are given.

In order to address an all-inorganic halide lead-free perovskite for potential photovoltaic applications, we carried out first-principles calculations of bandgaps of 260 all-inorganic halide perovskites belonging to the class ABX3, with A = Li, Na, K, Rb, Cs, B = Pb, Sn, and Ge, and X = F, Cl, Br, I. Three most common crystal symmetries were chosen, including cubic, tetragonal, and two orthorhombic phases. The bandgap exhibited increase with the decreasing of the anions radius (I, Br, Cl, F) and lowering the symmetry of the structures. With consideration of multiple factors forming perovskites, we reported three all-inorganic lead-free halides perovskites including cubic-KSnCl3, cubic-RbSnCl3, and trigonal-NaGeBr3as candidates with desirable bandgap (1.24–1.44 eV) for photovoltaic applications.

The long carrier lifetimes in perovskite single crystals have drawn significant attention recently on account of their irreplaceable contribution to high-performance photovoltaic (PV) devices. Herein, the optical and optoelectronic properties of CH3NH3PbI3and CH3NH3PbI3–xBrx(with five different contents of Br doped) single crystals were investigated. Notably, a superior carrier lifetime of up to 262 μs was observed in the CH3NH3PbI3–xBrx(I/Br = 10:1 in the precursor) single-crystal PV device under 1 sun illumination, which is two times longer than that in the CH3NH3PbI3single crystal. Further study confirmed that the ultralong carrier lifetime was ascribed to the integrated superiority derived from both the low trap-state density and high charge-injection efficiency of the device interface. On this basis, appropriate incorporation of Br is useful in the design of better PV devices.

S-Adenosylhomocysteine hydrolase (SAHase) is a cellular enzyme that plays a key role in the methylation process, and a potential drug target in the discovery of antiviral and anticancer agents. There is increasing interest in determining its activity in the biological and clinical fields with chemosensors but with limited success so far. Herein, we designed and developed for the first time an off/on-type of fluorogenic substrate (NADE) that is directly responsive to SAHase activity. NADE used 1,8-naphthalimide as the signal reporter and adenosine (Ade) as the reaction center; removal of the Ade moiety enhanced the fluorescence by >10-fold. Kinetic study showed that NADE followed a non-Michaelis–Menten pattern that corresponded to the allosteric behavior of SAHase. NADE showed excellent selectivity and functioned efficiently in cells, allowing the microscopic imaging of SAHase activity. NADE can also be used to identify and measure the effectiveness of inhibitors in a markedly superior way. In a word, NADE would be broadly useful in clinical applications and academic studies.

We present here a double-optimizations-of-buffer-region (DOBR) microiterative scheme for high-efficiency energy minimizations of large, flexible systems in combined quantum-mechanical/molecular-mechanical (QM/MM) calculations. In the DOBR scheme, an entire system is divided into three regions: the core, buffer, and outer regions. The core region includes QM atoms and the MM atoms within a cutoff distance R1to the QM atoms (denoted by MM1atoms), and the buffer region consists of MM atoms within another cutoff distance R2to MM1atoms. Each DOBR microcycle involves two steps: First, QM atoms are assigned electrostatic-potential (ESP) charges, and the buffer and outer regions are optimized at the MM level with the core region kept frozen. Second, the core and buffer regions are optimized at the QM/MM level using the electrostatic embedding with the outer region kept frozen. The two steps are repeated until two optimizations converge at one structure. The DOBR scheme was tested in the optimizations of nucleobases solvated in water spheres of 30 Å radius, where the initial geometries were extracted from the trajectories of classical molecular dynamics simulations, and the cutoff distances R1and R2were set to 5.0 and 4.0 Å, respectively. For comparisons, the optimizations were also carried out by a “standard” scheme without microiteration and by the two-region microiterative (TRM) method. We found that the averaged number of QM calculations for the DOBR scheme is only ∼1% of that of the standard scheme and ∼6% of the TRM approach. The promising results indicate that the DOBR scheme could significantly increase the efficiency of geometry optimizations for large, flexible systems in QM/MM calculations.

Two-photon-pumped amplified spontaneous emission (ASE) of CH3NH3PbBr3microdisks (MDs) were investigated by using femtosecond laser system. Low threshold at 2.2 mJ cm–2was obtained. Also, emission spectral tunability from 500 to 570 nm was demonstrated by synthesis the mixed halide perovskite MDs. The spatial effect of photoluminescence (PL) properties under one-photon and two-photon excitation were also studied by means of two-photon laser scanning microscope (TPLSM) and time-resolved PL spectroscopy. It was found that the band to band emission of near-surface regions and photocarriers’ diffusion from near-surface regions to interior regions is significant for one-photon excitation. By contrast, reabsorption of emission under two-photon excitation plays a major role in the emission properties of the MDs. These results will give a more comprehensive understanding of the nonlinear effect of CH3NH3PbBr3single crystals.

Sb-alloyed Pb-free halide perovskite Cs4MnBi2Cl12serves as photocatalyst for overall photocatalytic conversion of CO2into CO and oxidation water to H2O2owing to the suppression of fluorescence emission path via Sb alloying.

Dem Ruhekomplex auf der Spur: [{IrCp*Cl2}2] katalysiert die Redoxcyclisierung von Nitronalkinen wie 1unter Bildung von Azomethinyliden, die anschließend mit Elektrophilen und π‐Bindungen umgesetzt werden können. Der ungewöhnliche O‐gebundene Azomethinkomplex 2wurde isoliert und als Ruhezustand des Katalysators in der Azomethinylid‐Bildung identifiziert. Cp*=C5Me5.

Cat. at rest: [{IrCp*Cl2}2] readily catalyzes the redox cyclization of nitron alkynes (e.g., 1) to give azomethine ylides that can then react with electrophiles and π bonds. The unusual O‐bound azomethine complex 2was isolated and identified as the resting state of the catalyst in the azomethine ylide formation. Cp*=C5Me5.

[(Aryl‐ppy)Pt(acac)] (ppy = 2‐phenylpyridine, acac = acetylacetonato) derivatives with triphenylamine (TPA) substituents on the ppy ligand have been prepared. The TPA fragment is either directly cyclometallated (Pt‐1) or attached to the ppy ligand through a C–C single bond (Pt‐2) or a novel α‐diketo group (Pt‐3). All the complexes show room‐temperature phosphorescence in fluid solution with emission bands in the range of 530–590 nm, which are red‐shifted relative to the model complex [ppyPt(acac)] (λem= 486 nm). This emission colour tuning effect is attributed to either an elevated HOMO energy caused by electron‐donating TPA substituents on the ppy ligand or a decreased LUMO energy caused by the electron‐trap effect of electron‐withdrawing substituents; both result in a smaller HOMO–LUMO energy gap and thus red‐shifted emission. The complexes show extended luminescence lifetimes (τ= 3.0–5.5 μs) relative to the parent complex [ppyPt(acac)] (τ= 2.6 μs). The luminescent oxygen‐sensing properties of the complexes were studied in solution and polymer films. White light emission was observed with an OLED device fabricated with complex Pt‐3with CIE coordinates of (0.32, 0.32).

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Protonenfreisetzung: IrI‐Phosphan‐Komplexe mit fünffach koordiniertem Ir‐Zentrum und protischen N‐heterocyclischen Carbenliganden wurden synthetisiert, die NH⋅⋅⋅Cl‐Brücken enthalten (siehe Schema; cod=1,5‐Cyclooctadien). Der Austausch von Cl−gegen schwächer koordinierende Anionen führt zur reversiblen 1,3‐Wanderung des NH‐Protons zum Iridiumatom, wahrscheinlich über einen neuartigen, wasservermittelten Protonenrelais‐Mechanismus.

A parallel study on silver, gold, and platinum catalysts with inert silica support is conducted both experimentally and theoretically for the liquid-phase hydrogenation of crotonaldehyde (Me−CHCH−CHO). We find that the silver catalyst exhibits a uniquely high selectivity toward CO hydrogenation and the selectivity remains constant even at the conversion close to 100%. The gold catalyst, however, shows only a moderate selectivity whereas the platinum catalyst has a rather poor selectivity. Such variation in selectivity is interpreted in terms of the varied adsorption geometries of the crotonaldehyde on different metals. According to our density functional calculations of the chemisorptions of crotonaldehyde on selected M19(M = Ag, Au, and Pt) model clusters and M(111) surface, the most favored adsorption mode for silver is the CO oxygen atom being σ-bonded on low-coordinated silver atoms, which results in activation of the CO bond. In contrast, so-called η4and di-σCCmodes are preferred on Pt surface, while a πCCadsorption mode is favored on low-coordinated gold atoms, which leads to the preference of CC hydrogenation. Moreover, the calculations indicate that the selectivity to CO hydrogenation is more favored on smaller silver nanoparticles. This implication has been further corroborated experimentally by investigation of silver catalysts with different particle sizes.

Molecular dynamics (MD) simulations followed by molecular mechanics generalized Born surface area (MM‐GBSA) analyses have been carried out to study the selectivity of two neutral and weakly basic P1 group inhibitors (177 and CDA) to thrombin and trypsin. Detailed binding free energies between these inhibitors and individual protein residues are calculated by using a per‐residue basis decomposition method. The analysis of the detailed interaction energies provides insight on the protein–inhibitor‐binding mechanism and helps to elucidate the basis for achieving selectivity through interpretation of the structural and energetic results from the simulations. The study shows that the dominant factor of selectivity for both inhibitors is van der Waals energy, which suggests better shape complementarity and packing with thrombin. Nonpolar solvation free energy and total entropy contribution are also in favor of selectivity, but the contributions are much smaller. Binding mode and structural analysis show that 177 binds to thrombin and trypsin in a similar binding mode. In contrast, the CDA binds to thrombin and trypsin in very different modes.

Molecular dynamics simulations followed by quantum mechanical calculation and Molecular Mechanics Poisson-Boltzmann Surface Area (MM-PBSA) analysis have been carried out to study binding of proline- and pyrazinone-based macrocyclic inhibitors (L86 and T76) to human α-thrombin. Detailed binding interaction energies between these inhibitors and individual protein fragments are calculated using DFT method based on a new quantum mechanical approach for computing protein-ligand interaction energy. The analysis of detailed interaction energies provides insight on the protein-ligand binding mechanism. Study shows that T76 and L86 bind to thrombin in a very similar “inhibition mode” except that T76 has relatively weaker binding interaction with Glu217. The analysis from quantum calculation of binding interaction is consistent with the MM-PBSA calculation of binding free energy, and the calculated free energies for L86/T76-thrombin binding agree well with the experimental data.

An aromatic isocyanide-substituted diiron complex 5 has been synthesized as a mimic for the active site of Fe-only hydrogenases. Its structure has been fully characterized by X-ray crystallography. The 4-iodophenylisocyanide ligands in 5 are in the basal positions and are nearly parallel to each other, with π–π stacking interactions. Four isomeric geometries of complex 5 have been optimized by DFT calculations, and the electrochemical properties of 5 have been investigated by cyclic voltammetry in the absence and presence of p-toluenesulfonic acid (HOTs). Analysis of the cyclic voltammetric curve indicates that the reduction event at about–1.43 V is electrocatalytically active to proton reduction. This potential is more positive than that of any functionalized propanedithiolatodiiron complex. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

The reaction mechanism of the l-proline-catalyzed α-aminoxylation reaction between aldehyde and nitrosobenzene has been investigated using density functional theory (DFT) calculation. Our calculation results reveal following conclusions [1]. The first step that corresponds to the formation of C–O bond, is the stereocontrolling and rate-determining step [2]. Among four reaction channels, the syn-attack reaction channel is more favorable than that of the anti one, and the TS-ss channel dominates among the four channels for this reaction in the step of C–O bond formation [3]. The intermolecular hydrogen bond between the acidic hydrogen of l-proline and the N atom of the nitrosobenzene in an early stage of the process catalyzes very effectively the C–O bond formation by a large stabilization of the negative charge that is developing at the O atom along the electrophilic attack [4]. The effect of solvent decreases the activation energy, and also, the calculated energy barriers are decrease with the enhancement of dielectric constants for C–O bond formation step. These results are in good agreement with experiment, and allow us to explain the origin of the catalysis and stereoselectivity for l-proline-catalyzed α-aminoxylation of aldehyde reaction. The addition of H2O to substituted imine proline, intermolecular proton-transfer steps, and the l-proline elimination process were also studied in this paper.The reaction mechanism of the l-proline-catalyzed α-aminoxylation reaction between aldehyde and nitrosobenzene has been investigated using density functional theory (DFT) calculation. Our calculation results reveal following conclusions [1]. The first step that corresponds to the formation of C–O bond, is the stereocontrolling and rate-determining step [2]. Among four reaction channels, the syn-attack reaction channel is more favorable than that of the anti one, and the TS-ss channel dominates among the four channels for this reaction in the step of C–O bond formation [3]. The intermolecular hydrogen bond between the acidic hydrogen of l-proline and the N atom of the nitrosobenzene in an early stage of the process catalyzes very effectively the C–O bond formation by a large stabilization of the negative charge that is developing at the O atom along the electrophilic attack [4]. The effect of solvent decreases the activation energy, and also, the calculated energy barriers are decrease with the enhancement of dielectric constants for C–O bond formation step. These results are in good agreement with experiment, and allow us to explain the origin of the catalysis and stereoselectivity for l-proline-catalyzed α-aminoxylation of aldehyde reaction. The addition of H2O to substituted imine proline, intermolecular proton-transfer steps, and the l-proline elimination process were also studied in this paper.

The Universal Mobile Telecommunications System (UMTS) is the third‐generation (3G) wireless technology that will offer the expanded bandwidth to allow for enhanced services in data and multimedia. UMTS will support both circuit‐switched and packet‐switched access to Internet services. However, the introduction of the 3G wireless technology will incur significant expense to operator networks. The success of UMTS for network operators may well depend upon the delivery of highly desirable applications and mobile Internet services. Concomitant with this will be how well the accounting solution within the UMTS core network integrates into an end‐to‐end billing model that is able to return and distribute revenue to both service providers and network operators. © 2002 Lucent Technologies Inc.

We report the study of translational-vibrational energy transfer in the A+BC scattering using the dynamical Lie algebraic approach combined with the intermediate picture. The rotational sudden approximation is applied to treat the rotational motion of the BC molecule, which is regarded as an anharmonic oscillator. The calculated results show that the transition probabilities increase with increasing rotational quantum number. Comparison with those obtained in the collinear collision of system A+BC manifests that the transition probabilities here increase indeed. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 81: 214–221, 2001

The dynamical Lie algebraic approach developed by Alhassid and Levine combined with intermediate picture is applied to the study of translational–vibrational energy transfer in the collinear collision between an atom and an anharmonic oscillator. We find that the presence of the anharmonic terms indeed has an effect on the vibrational probabilities of the oscillator. The computed probabilities are in good agreement with those obtained using exact quantum method. It is shown that the approach of dynamical Lie algebra combining with intermediate picture is reasonable in the treating of atom–anharmonic oscillator scattering.

The dynamical Lie algebraic approach developed by Y. Alhassid and R. D. Levine (Phys Rev A 1978, 18, 89) combined with the intermediate picture is applied to the study of translational-vibrational energy transfer in the collinear collision between an atom and an anharmonic oscillator. By solving equations of motion for the group parameters under the first-order approximation of the group parameters, we calculate the vibrational transition probabilities of anharmonic molecule scattering with an atom in the intermediate picture. Numerical test calculations are carried out for the collinear scattering system HBr+He; the results show that the dynamical Lie algebraic approach can be useful for the description of atom-molecule collision phenomena. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 78: 295–302, 2000

Although converting the greenhouse gases carbon dioxide (CO2) into solar fuels is regarded as a convenient means of solar energy storage, the intrinsic mechanism on how the high chemical inertness linear CO2molecules is activated and converted on a semiconductor oxide is still elusive. Herein, by creating the oxygen vacancies on the typical hexagonal tungsten oxide (WO3), we realize the continuous photo-induced CO2reduction to selectively produce CO under light irradiation, which was verified by isotope labeling experiment. Detailed oxygen vacancies evolution investigation indicates that light irradiation can simultaneously induce the in-situformation of oxygen vacancies on hexagonal WO3, and the oxygen vacancies promote the adsorption and activation of CO2molecules, leading to the CO2reduction to CO on the hexagonal WO3viaan oxygen vacancies-involved process. Besides, the existence of water further promotes the formation of CO2reduction intermediate, further promote the CO2photoreduction. Our work provides insight on the mechanism for converting CO2into CO under light irradiation.

Herein, a phenylamine cation based dopant (PHC) is demonstrated as the efficient and stable Spiro-OMeTAD single dopant within PSCs where the [Spiro-OMeTAD]•+radical is primarily generated by intermolecular dipole moment derived charge transfer. Beyond the prominent advantages of PHC in hydrophobic and larger van der Waals radius of phenylamine cation as compared to Li+ion which is favorable for stability of PSCs, the detailed findings reveals that it could also convert deep trap states to shallow tarp states via orbital shifting and hybridization for perovskite, in addition supplies the populated states near valence band and reinforced interface build-in filed (Ebi) which extremely restrain non-radiative recombination and enhances the carriers transfer with decreased barriers for hetero-junction interface. As a result, the efficiency of devices reaches 21.34% with ultrahigh FF of 80.24% versus 20.66% for the device based on Li-TFSI/t-BP bi-dopants which is the best efficiency of PSCs based on single dopant. Besides, the PHC based PSCs also displays much higher long-term stability up to 40 days under air ambient without encapsulation.

All-inorganic lead halide perovskite nanocrystals (NCs) have attracted extensive attention due to their three-dimensional (3D) structure, simple synthesis, and outstanding optical and electronic properties. However, the toxicity of lead and poor stability hindered their further development. Recently, air-stable, nontoxic, all-inorganic lead-free perovskite NCs have been developed and widely studied. Two Pb2+ions can be replaced with monovalent B+and trivalent B′3+cations to form the halide double perovskite (DP) Cs2BB′X6(B+= Ag+, Na+, or Cu+; B′3+= Bi3+, Sb3+, In3+, or Fe3+; X–= halogen anion) NCs, which are characterized by a 3D network similar to lead-based perovskite NCs and have potential to be excellent photoelectric materials. In this review, we present the recent advances in synthesis, optical properties, exciton dynamics, and optoelectronic applications of all-inorganic 3D halide DP NCs. In the end, the opportunities and challenges of all-inorganic 3D DP NCs have been proposed. This review not only provides a feasible idea for understanding the exciton dynamics in lead-free DP NCs but also guides the design and development of new, high-performance, stable lead-free DP NCs.

Longevity has been a long-standing challenge for perovskite photovoltaics. In general, Li-TFSI/t-BP are the state-of-the-art bi-dopants for the hole-transporting layer (HTL) in perovskite solar cells (PSCs), although such dopants significantly diminish the stability of devices. Here, we reported a novel dopant of fluorinated iron(III) porphine (Fe(III)-PP) as a potential alternative to the Li-TFSI/t-BP. The optimized PSCs exhibit a champion power conversion efficiency (PCE) of 21.73%, which outperforms the standard bi-dopants Li-TFSI/t-BP (21.07%). The high migration barrier together with the hydrophobic nature of the Fe(III)-PP, which in turn suppress intrinsic ion migration and alleviate extrinsic moisture-induced degradation, resulting in prominent improvement of long-term stability of PSCs up to 1200h under air exposure without encapsulation.

Cystathionine lyase, the key enzyme in transsulfuration and reverse transsulfuration pathways, is involved in a wide array of physiological and pathophysiological processes in both mammals and nonmammals. Though the biological significance of the hydrogen sulfide/cystathionine lyase system in disease states is extensively discussed, the absence of molecular methods for direct monitoring of cystathionine lyase in complex biosamples renders the result unreliable and perplexing. Here, we present the first attempt at designing and developing effective activatable fluorescent probes for cystathionine lyase based on the naphthylamide scaffold. CBLP and CSEP were designed based on the catalytic preference of cystathionine β-lyase (CBL) and cystathionine γ-lyase (CSE). Briefly, incorporation of cysteine/homocysteine as the recognition moiety and a carbamate ethyl sulfide group as a self-immolated linker proved to be an effective strategy for cystathionine lyase fluorescence reporting. CBLP exhibits high selectivity and sensitivity in vitroin semiquantifying CBL levels in roots of wild-type Arabidopsis thalianaand cbl mutants (cbl knockout: SALK_014740C, overexpressed: OE-CBL). Meanwhile, CSEP successfully detected CSE levels in HCC-LM3 cells, zebrafish models, and upregulated CSE in frozen section slides from the liver tissue of cecal ligation and puncture (CLP)-induced septic rats, which was also validated by Western blotting and immunohistochemical analysis. In summary, the practical design strategy facilitates profiling of cystathionine lyase activity in biological processes. It may pave the way for the development of accurate and efficient methods for the direct estimation of cystathionine lyase.

Generally, the method provides a facile approach to alkenylated isocoumarins.