Electron-donating Ability Research Articles

Heteroheptacene-based acceptors with thieno[3,2-b]pyrrole yield high-performance polymer solar cells.

Rationally utilizing and developing synthetic units is of particular significance for the design of high-performance non-fullerene small-molecule acceptors (SMAs). Here, a thieno[3,2-b]pyrrole synthetic unit was employed to develop a set of SMAs (ThPy1, ThPy2, ThPy3 and ThPy4) by changing the number or the position of the pyrrole ring in the central core based on a standard SMA of IT-4Cl, compared to which the four thieno[3,2-b]pyrrole-based acceptors exhibit bathochromic absorption and upshifted frontier orbital energy level due to the strong electron-donating ability of pyrrole. As a result, the polymer solar cells (PSCs) of the four thieno[3,2-b]pyrrole-based acceptors yield higher open-circuit voltage and lower energy loss relative to those of the IT-4Cl-based device. What is more, the ThPy3-based device achieves a power conversion efficiency (PCE) (15.3%) and an outstanding fill factor (FF) (0.771) that are superior to the IT-4Cl-based device (PCE = 12.6%, FF = 0.758). The ThPy4-based device realizes the lowest energy loss and the smallest optical band gap, and the ternary PSC device based on PM6:BTP-eC9:ThPy4 exhibits a PCE of 18.43% and a FF of 0.802. Overall, this work sheds light on the great potential of thieno[3,2-b]pyrrole-based SMAs in realizing low energy loss and high PCE.

Crystal structures and electrochemical properties of nickel(II) complexes with N,N',N'',S-tetra-dentate Schiff base ligands.

The thiol-ate nickel complexes {2-[({2-[(2-amino-ethyl-κN)(meth-yl)amino-κN]eth-yl}imino-κN)meth-yl]benzene-thiol-ato-κS}nickel(II) chloride, [Ni(C12H18N3S)]Cl (1), and [2-({[2-(piperazin-1-yl-κ2 N 1,N 4)eth-yl]imino-κN}meth-yl)benzene-thiol-ato-κS]nickel(II) hexa-fluoro-phosphate di-chloro-methane monosolvate, [Ni(C13H18N3S)]PF6·CH2Cl2 (2), were synthesized by the reactions of 2-(tert-butyl-thio)-benzaldehyde, tri-amines, and nickel(II) salts. Both complexes have a nickel ion surrounded by an N,N',N'',S-tetra-dentate ligand, forming a square-planar geometry. The terminal N,N-chelating moiety is N,N-di-alkyl-ethane-1,2-di-amine for 1 and 1-alkyl-piperazine for 2. The N-Ni-N bite angle in the terminal N,N-chelate ring in 2 [76.05 (10)°] is much smaller than that in 1 [86.16 (6)°]. Cyclic voltammograms of 1 and 2 in aqueous media indicated that the reduction and oxidation potentials of 2 are more positive than those of 1. The smaller bite angle of the terminal piperazine chelate in 2 reduces the electron-donating ability of the tetra-dentate ligand, resulting in a positive shift of the redox potentials. Both complexes exhibit catalytic activity for proton reduction, and the piperazine moiety in 2 is effective in reducing the overpotential.

Polycatechol-Derived Mesoporous Polydopamine Nanoparticles for Combined ROS Scavenging and Gene Interference Therapy in Inflammatory Bowel Disease.

Benefiting from the evolution of nanotechnology, the combination therapy by gene interference and reactive oxygen species (ROS) scavenging are expected, which holds great potential in inflammatory bowel disease (IBD) therapy. However, the functional integration of different therapeutic modules through interface modification of gene vectors for safe and efficient treatment is urgently needed. Herein, we present a catechol chemistry-mediated core-shell nanoplatform for ROS scavenging-mediated oxidative stress alleviation and siRNA-mediated gene interference in a dextran sulfate sodium (DSS)-induced colitis model. The nanoplatform is constructed by employing mesoporous polydopamine nanoparticles (MPDA NPs) with surface modification of amines as the porous core for TNF-α-siRNA loading (31 wt %) and exerts an antioxidant function, while PDA-induced biomineralization of the calcium phosphate (CaP) coating is used as the pH-sensitive protective shell to prevent siRNA from premature release. The CaP layer degraded under weakly acidic subcellular conditions (lysosomes); thus, the synergistic integration of catechol and cation moieties on the exposed surface of MPDA resulted in an efficient lysosomal escape. Subsequently, effective ROS scavenging caused by the electron-donating ability of MPDA and efficient knocking down (40.5%) of tumor necrosis factor-α (TNF-α) via sufficient cytosolic gene delivery resulted in a synergistic anti-inflammation therapeutic effect both in vitro and in vivo. This work establishes the first paradigm of synergistic therapy in IBD by ROS scavenging and gene interference.

Computationally assisted design and prediction of remarkably boosted NLO response of organoimido‐substituted hexamolybdates

AbstractIn recent years, nonlinear optical (NLO) molecular material networks/frameworks have shown attractive application prospects in modern laser technology, data storage components, optical communication, and digital processing. Finding new and novel materials with excellent nonlinear optical properties has become an attractive research topic in the field of nonlinear optics. Herein, DFT calculations have been performed on hybrid organic‐inorganic composite push‐pull systems based on polyoxometalates (POMs). Systems (DPA1‐DPA4) are theoretically analyzed to study the second‐order NLO response and have been compared with reference compound. The effect of four substituent groups on NLO properties has been investigated. Based on optimized geometric configurations, dipole polarizability(α), first‐order hyperpolarization(β), transition energy (E), oscillation frequency (ƒ), and HOM0 (highest occupied molecular orbital)‐LUM0 (lowest unoccupied molecular orbital) analysis have been performed. All the studied systems possess significantly large second‐order polarizability and proven to be excellent nonlinear optical hybrid composite materials. The asymmetric polarization of charges caused by D‐π‐A combination in our studied systems is accountable for the improvement of nonlinear optical activity of these push‐pull compounds. POM cluster/cage is behaving as an electron donor, whereas charge transfer has been observed in the direction of chain length. On the bases of the electron donor and electron acceptor ability of these substituent groups, substantial influence on NLO response and charge transfer characteristics has been identified. Our studied systems are efficient NLO materials and will be helpful for the synthetic chemists to produce effective hybrid composites.

Hyperconjugative Interactions of the Carbon-Halogen Bond that Influence the Geometry of Cyclic α-Haloacetals.

The analysis of the structures of low-energy conformers of different α-haloacetals reveals changes in bond lengths and geometries that correspond to stabilizing orbital interactions that contribute to the ground-state structures of these systems. Several factors, including the electron-donating and electron-accepting abilities of the substituents on the ring, affect the degree of the electronic interactions in these carbohydrate-like systems. The presence of an α-halogen atom that can participate in hyperconjugation has been shown to contribute to the structural characteristics of the low-energy conformer. The experimental evidence is supported by natural bond order (NBO) analysis to identify the types of interactions and to assess their relative importance.

Novel polymeric metal complexes of salicylaldehyde schiff base derivative being used for dye sensitizer

For studying the effect of metal complexes used as auxiliary electron acceptors of dye sensitizers in dye sensitized solar cell (DSSC) on photovoltaic performance, four polymeric metal complexes, which adopt 1,4-dioctyloxy-2,5-dibromobenzene or thienylbenzo-[1,2-b:4,5-b']-dithiophene (BDTT) as electron donor (D), salicylaldehyde schiff base derivatives as auxiliary acceptor (A), 8-hydroxyquinoline derivative as π bridge and acceptor (A), were designed, synthesized and characterized. The influence of different donor and metal complexes of the four dye sensitizers on performance were discussed by determining their thermal, photophysical, electrochemical and photovoltaic properties. The DSSC devices based on the four polymeric metal complexes PBDTT–SF–Cd, PBDTT–SF–Cu, PPV-SF-Cd and PPV-SF-Cu exhibited a short-circuit photocurrent density (Jsc) of 14.94 mA cm−2, 14.86 mA cm−2, 10.23 mA cm−2 and 9.80 mA cm−2 as well as acquired power conversion efficiency (PCE) of 8.59%, 8.45%, 5.29% and 4.77% respectively under the AM 1.5 irradiation (100 mW cm−2). Both Jsc and PCE value of the four polymeric metal complexes are in a decreased order. The phenomenon is attributed to not only the variable strength of coordination bond formed between metal ion and ligand, which can be affected by the radius and charge number of metal ion, but also the better electron-donating ability of BDTT. In common charge number, bigger radius of metal ion will cause more powerful coordination bond as well as greater electron-withdrawing ability of auxiliary acceptor and charge-transfer ability between donor and acceptor. This work provides a distinctive perspective for the design of D-A-π-A motif complexes in DSSC application.

Boron nitride quantum dots coupled with CoP nanosheet arrays grown on carbon cloth for efficient nitrogen reduction reaction

As a promising alternative technology to the Haber-Bosch process for industrial-scale NH3 production, Electrochemical nitrogen reduction reaction (NRR) is considered a sustainable and environmentally-benign alternative N2-to-NH3 conversion. Although low-cost cobalt phosphide (CoP) is a potential efficient NRR electrocatalyst, the relatively low activation capability of the N≡N triple bond significantly limits the further improvement of the electrocatalytic activity. Herein, the boron nitride quantum dots (BN QDs) are densely assembled on the surfaces of CoP nanosheets array/carbon cloth (CC) to enhance the electrocatalytic NRR performance. The results demonstrate that the BN QDs@CoP/CC delivers a high NH3 yield rate of 5.39 × 10−10 mol s−1cm−2 at the potential of −0.40 V (vs. RHE) and high faradaic efficiency (FE) of 10.34% at the potential of −0.35 V (vs. RHE) in 0.1 M Na2SO4 electrolyte. The combination of BN QDs and CoP significantlyinhibitedcompetitiveHERprocess. Also, the BN QDs@CoP/CC shows good durability with a high yield rate of NH3 and FE within the recycling test 7 times. Density functional theory calculations reveal that the N2 molecules prefer to be adsorbed on the edge-B sites of BN QDs which provide additional abundant surface-active sites. More importantly, the electron enrichment on the edge-B atoms improves their electron-donating ability to activate stable N≡N bonds, for which the BN QDs@CoP/CC performs better NRR activity and selectivity.

Synthesis of Bis(N,N-diethyl)aniline-Based, Nonlinear, Optical Chromophores with Increased Electro-Optic Activity by Optimizing the Thiolated Isophorone Bridge

Six nonlinear, optical chromophores, Z1–Z6, based on the bis(N,N-diethyl)aniline-derived donor and thiolated isophorone bridge, were designed and synthesized. The bis(N,N-diethyl)aniline-derived donor was applied in a chromophore with thiolated isophorone as an electron bridge for the first time. In particular, the bridge parts of chromophores Z2–Z6 were modified with different functional groups, including tert-butyltrimethylsilane and tert-butyl(methyl)diphenylsilane derivative: 1,3-bis(trifluoromethyl)benzene and alkylaniline cyanoacetate, respectively. Density functional theory calculations suggested this series of chromophores show much greater hyperpolarizability than traditional, nonlinear, optical chromophores due to strong electron donor ability. These chromophores, Z1–Z6, showed very high poling efficiencies due to the large steric hindrance and hyperpolarizability of the chromophores. A large poling efficiency (2.04 ± 0.08 nm2/V2) and r33 value (193 pm/V) were achieved for polymeric thin films doped with 25 wt% chromophore Z6 at 1310 nm.

Performance of ferroelectric visible light type II Ag10Si4O13/TiO2 heterojunction photocatalyst

Water remediation using semiconductor photocatalysts under visible light (VL) irradiance appears as a more sustainable technology option due to the greater penetration depth. Consequently, the overall band spectrum of VL has received significant attention to providing solutions to secure clean water resources over the past few decades. This research developed an innovative approach to enhancing the visible light susceptibility of semiconductor-based photocatalytic composites Ag10Si4O13/TiO2 (ASO/TO). The intrinsic properties of TO and electron donor ability of ASO lend synergistically to the generation of a narrow bandgap semiconductor. A feasible wet-chemistry method was found to engineer the electronic properties of ASO/TO under VL for rapid decolorization of methylene blue (MB). Inhibition experiments with several agents confirmed that the decolorization proceeds through the generation of hydroxyl radical species assisted by hole carrier generation at the ASO junction. The rate of MB decomposition followed a pseudo-first-order kinetic profile (98.2% within 35 mins under ambient conditions with 5 ppm of 2:1 ASO/TO and 20 ppm of MB). The XRD/XPS spectroscopic analysis confirms the electronic polarization of distorted SiO4 tetrahedral units coordinated to Ag-O, forming a double dumbbell double-helical structure. The staggered bandgap of these composite photocatalysts is associated with the Ag-Ag d10/sp hybridization and dispersive conduction band. At the same time, the 2p orbitals of TiO2 showed a less dispersive band due to the availability of d-orbitals. The generated Ag10Si4O13 (ASO) based ferroelectric materials allow amplifying its frequency due to internal polarization along the c-axis. The electrochemical evaluation also showed that the interface charge transfer resistance was lowered relative to TiO2, facilitating the efficacy of photocatalytic reactivity, where the generation of holes as charge carriers was the rate-limiting step. The novel nano-engineering strategy providing highly active photocatalysis can open new horizons for VL applications.

Au‐NHC complexes with thiocarboxylate ligands: Synthesis, structure, stability, thiol exchange and in vitro anticancer activity

Novel complexes of form (NHC)Au(SCOR) (NHC = N‐heterocyclic carbene, SCOR− = thiocarboxylate ligand) were synthesised and characterised by spectroscopic techniques and X‐ray diffraction studies. The results of NMR and X‐ray studies indicated that thiocarboxylate ligands are comparable with NHCs in their electron donor ability. The complexes were stable at room temperature in the solid state but in solution underwent disproportionation reactions to form equilibria with [Au(NHC)2]+ and [Au(SCOR)2]−. In solution, the thiocarboxylate ligand in (NHC)Au(SCOR) underwent rapid exchange with other thiocarboxylate or thiolate ligands. The (NHC)Au(SCOR) complexes showed toxicity against cisplatin‐resistant ovarian cancer cells (OVCAR‐8), with IC50 < 10 μM, in the range exhibited by cationic [Au(NHC)2]+ complexes well‐known for their promising anticancer activity.

The halogen effect of perylene diimide-based non-fullerene acceptors on photovoltaic properties

To develop photovoltaic materials based on perylene diimide, two non-fullerene acceptors namely PCPD-F and PCPD-Cl are rationally designed and readily synthesized. By introducing the cyclopentadithiophene unit with the strong electron-donating ability, PCPD-F and PCPD-Cl exhibit strong and bathochromic absorption compared to other perylene diimide derivatives. Meanwhile, different halogens in PCPD-F and PCPD-Cl significantly affect the physicochemical properties and device performance. With the substitution of chlorine atom, PCPD-Cl shows relatively broad absorption and strong crystallinity. However, the chlorination makes PCPD-Cl less miscible with polymer donors, leading to the unfavorable morphology with large-scale phase separation in organic solar cells. Consequently, the device based on PCPD-F achieves the best power conversion efficiency of 9.03% by blending with the polymer donor PM6, which is among the high-performance organic solar cells based on perylene diimide. This work demonstrates it is crucial to meticulously select the substituted atom and position in the design of non-fullerene acceptors.

Dimethyl malonate based organic compounds bearing different aromatic substituents: Synthesis, photophysics and application in anti-blue light lenses

Five new organic conjugated molecules (TM1–TM5) based on the electron-withdrawing unit (dimethyl malonate) were synthesized and studied. Among them, TM1–TM4 exhibited intense absorption bands from ultraviolet to blue region, which were mainly arisen from the π–π* transitions, mixed with intramolecular charge transfer (ICT) characters. The absorption bands in the region of 360–450 nm for TM5 might be assigned to ICT transitions, mixed with the π–π* feature. Meanwhile, the increasing electron-donating ability of the substituents caused a bathochromic shift of emission. The different electron-donating substituents in the molecular structure make a slight difference in oxidation potential. Furthermore, there is almost no mass loss up to 200 °C for these compounds and all of them exhibit the satisfactory photostability. In addition, the anti-blue light performance of these compounds doped in optical films was studied and TM5 exhibited the best anti-blue light performance. These photophysical, photochemical and electrochemical properties indicated that organic conjugated small molecules containing dimethyl malonate unit are excellent optical functional materials for anti-blue light applications.

New donor–π–acceptor AIEgens: Influence of π bridge on luminescence properties and electroluminescence application

Aggregation-induced emission (AIE) offers a solution to harvest strong solid-state fluorescence, which is crucial to achieving efficient organic light-emitting diodes (OLEDs). In this study, two novel AIE luminogens (AIEgens) were designed by integrating the advantages of triphenylamine (TPA) and phenanthroimidazole (PI), which exhibited excellent electron-donating ability of TPA and bipolar characteristics and suitable carrier transporting ability of PI. The two structural units were connected by a π bridge of tris/tetrastyrene group with a different number of benzene rings. Intra-/inter-molecular charge transfer can be obtained by adjusting the conjugation of the π bridge, and the AIE activity is also manipulated accordingly. The dilute solutions of TPE-TPAPPI present concentration- and polarity-dependent emission, demonstrating emission Adjustability by controlling the ratio of intramolecular and intermolecular charge transfer. It is found that intermolecular charge transfer dominates in film state. A non-doped OLED based on TPE-TPAPPI shows a maximum external quantum efficiency (EQE) of 4.01% with a low turn-on voltage of 3.2 V. The efficiency roll-off is only 4.75% even at a high brightness of 1000 cd m−2, demonstrating the superiority of our AIEgens in OLED application.

The selective regulation of borylation site based on one-shot electrophilic C–H borylation reaction, achieving highly efficient narrowband organic light-emitting diodes

The electrophilic borylation site of borylation reaction can be selectively controlled by varying the steric hindrance and electron-donating ability of the substrate substituent. The device based on the synthesized compound exhibits EQE of 21.6% with FWHM of 28 nm and CIE coordinates of (0.135, 0.094). The work provides an effective way for the development of high-performance MR-TADF emitter. • The electrophilic borylation site of one-shot electrophilic C–H borylation reaction can be selectively controlled. • New compounds tDPAC-BN and tDMAC-BN exhibited high PLQYs, narrow FWHMs, and satisfactory TADF properties. • The device based on tDPAC-BN achieved EQE of 21.6% with FWHM of 28 nm and CIE coordinates of (0.135, 0.094). Developing novel thermally activated delayed fluorescence (TADF) materials with a small full-width at half-maximum (FWHM) is very important for the fabrication of wide gamut and high-resolution displays of organic light-emitting diodes (OLEDs). In this work, we report two blue TADF emitters (tDPAC-BN and tDMAC-BN) with narrow FWHM based on a one-shot electrophilic C–H borylation reaction by selecting acridan-containing arylamine derivatives as the starting materials of borylation. The rigid skeleton structure significantly reduces vibrational motion, endowing tDPAC-BN and tDMAC-BN with high PLQYs (94.4% and 89.7%) and narrow FWHMs (19 nm and 26 nm in toluene). The electroluminescent devices employing tDPAC-BN and tDMAC-BN as emitters exhibit external quantum efficiency (EQE) of 21.6% and 22.3%, and CIE coordinates of (0.135, 0.094) and (0.116, 0.186), respectively. More importantly, we found the electrophilic borylation site of borylation reaction can be controlled by varying the steric hindrance effect and electron-donating ability of the substrate substituent. The different HOMO distribution originated from the differences in the substrate substituent accounts for different cyclization mode for tDPAC-BN and tDMAC-BN. Therefore, the work provides a useful strategy for broadening the range of high-performance TADF materials with narrow FWHM.

Design of porous organic polymer photocatalysts based on heptazine for efficient photocatalytic aerobic oxidation

• Four heptazine-based porous organic polymers with different diamines were prepared. • The structure–activity relationships of the POPs have been systematically studied. • The diamine linker has important roles on its physicochemical property and activity. • POP-4 has the best performance for the photocatalytic oxidation of benzylamine. • Its conversion and selectivity of benzylamine oxidation are both>99 %. Heptazine-based porous organic polymers (POPs), as new potential photocatalytic materials, have spurred extensive research interest, but there are few reports on the systematic study of the relationship between their structure and properties. Herein, we have prepared four heptazine-based POPs by using cyameluric chloride (C 6 N 7 Cl 3 ) as precursor, piperazine (POP-1), p-phenylenediamine (POP-2), biphenyl diamine (POP-3) and 4,4′'-diamino-p-terphenyl (POP-4) as basic blocks, respectively, and studied the effects of the composition and structure of POPs on their spectrum, specific surface area, interface contact in acetonitrile, electronic structure, carrier separation and photocatalytic aerobic oxidation of amine through experiments and density functional theory (DFT) calculations systematically. The results show that with the increase of the benzene rings and electron density of diamine linker, the electron-donating ability of these heptazine-based POPs significantly enhances, which reduces the band gap of the materials, improves their electronic donor–acceptor (D-A) interaction with heptazine, promotes the transfer and separation of photogenerated carriers, and thus endowing them significantly higher photocatalytic performance. Notably, POP-4 shows the best photocatalytic aerobic oxidation activity of benzylamine, which is significantly higher than that of g-C 3 N 4 . The conversion and selectivity of benzylamine to corresponding imine are both>99 % within 4 h under 10 W 420 nm LED light irradiation. This work paves the way for the rational design of efficient heptazine-based POP photocatalysts and promotes the development of heptazine-based functional materials.

Understanding steric-charge-dependence of conjugated passivators on π-Pb2+ bond strength for efficient all-inorganic perovskite solar cells

Intramolecular structure of interfacial passivator highly determines the bond strength with detrimental defects located at perovskite surfaces and grain boundaries. Herein, we investigate the steric-charge-dependence of various π-conjugated pyridine derivatives on electron-donating ability to passivate inorganic CsPbIBr2 perovskite film. The primary results demonstrate that the photovoltaic performances tightly correlate with the multidentate coordination sites and structure-steric hindrance because of their synergistic regulation on intramolecular electron-cloudy density and charge extraction. Comparing to pyridine and terpyridine treated devices, the bipyridine passivated device delivers an increased efficiency of 11.04% with a high open-circuit voltage of 1.301 V and improved stability after persistent irradiation over 20 h and storage for 60 days, which is one of the highest efficiencies for carbon-based all-inorganic CsPbIBr2 solar cells. This work provides a direction to choose ideal passivator for high-efficiency perovskite optoelectronics.

Computational Investigation of the Bisphenolic Drug Metabolism by Cytochrome P450: What Factors Favor Intramolecular Phenol Coupling.

Intramolecular phenol coupling reactions of alkaloids can lead to active metabolites catalyzed by the mammalian cytochrome P450 enzyme (P450); however, the mechanistic knowledge of such an "unusual" process is lacking. This work performs density functional theory computations to reveal the P450-mediated metabolic pathway leading from R-reticuline to the morphine precursor salutaridine by exploring possible intramolecular phenol coupling mechanisms involving diradical coupling, radical addition, and electron transfer. The computed results show that the outer-sphere electron transfer with a high barrier (>20.0 kcal/mol) is unlikely to happen. However, for inter-sphere intramolecular phenol coupling, it reveals that intramolecular phenol coupling of R-reticuline proceeds via the diradical mechanism consecutively by compound I and protonated compound II of P450 rather than the radical addition mechanism. The existence of a much higher radical rebound barrier than that of H-abstraction in the quartet high-spin state can endow the R-reticuline phenoxy radical with a sufficient lifetime to enable intramolecular phenol coupling, while the H-abstraction/radical rebound mode with a negligible rebound barrier leading to phenol hydroxylation can only happen in the doublet low-spin state. Therefore, the ratio [coupling]/[hydroxylation] can be approximately reflected by the relative yield of the high-spin and low-spin H-abstraction by P450, which thus can provide a theoretical ratio of 16:1 for R-reticuline, which is in accordance with previous experimental results. Especially, the high rebound barrier of the phenoxy radical derived from the weak electron-donating ability of the phenoxy radical is revealed as an intrinsic nature. Therefore, the revealed intramolecular phenol coupling mechanism can be potentially extended to several other bisphenolic drugs to infer groups of unexpected metabolites in organisms.

High performance electrode material for Li-organic battery based on quinoxalin-thiophene conjugated polymer/carbon powder composite

In this work, thiophene derivatives were selected as donor units and pyrazine derivatives as receptor units to synthesize two composite materials consisting of supercapacitor carbon (SC) loaded with poly [2,3-bis (2-pyridinyl)-5,8-bis (2-thiophenyl) quinoxaline] (PPTQ) or poly [2,3-bis (2-pyridinyl)-5,8-bis (2-(3,4-ethylenedioxythiophene) quinoxaline] (PPETQ) by cationic radical polymerization. First, chemical bonds structure, surface morphology, and element valence states of these materials were characterized by infrared (IR), scanning electron microscopy (SEM) and XPS in turn. CV curves were used to determine their initial oxygen reduction potentials and to calculate their HOMO and LUMO values, both polymers have a narrow band gap, with Eg values lower than 2 eV. The polymer composite materials were tested as anodes in lithium-ion batteries, with a lithium sheet used as the counter electrode. Then the constant current charge-discharge and electrochemical impedance spectroscopy (EIS) impedance were measured. The first discharge specific capacities of PPTQ@SC and PPETQ@SC were 895.9 mAh/g and 913.0 mAh/g at a current density of 100 mA/g, the formation of a SEI film occurred in the second cycle, and their coulomb efficiencies can reach more than 90% from the third cycle, and the discharge platform appeared at about 1.0 V. In contrast, due to its stronger electron-donating ability, the PPETQ polymer containing the 3,4-ethylenedioxythiophene (EDOT) group have better electrical conductivity and its honeycomb structure provides more active sites for the lithiation/delithiation redox process. Therefore, the specific capacity of PPETQ@SC are all higher than that of PPTQ@SC at different current densities.

A double donor-π-acceptor type hydrogen sulfide fluorescent probe with nanomolar level sensitivity and second level response time for evaluating metformin-induced hepatotoxicity

A dicyanomethylene-4H-pyran (DCM)-based fluorescent probe capable of hydrogen sulfide (H2S) sensing with limit of detection down to 3.89 nM, response time less than 1 s, two-photon excitation fluorescence (TPEF) feature has been developed. This probe was constructed by tethering an electron-withdrawing nitrobenzooxadiazole (NBD) moiety to the skeleton periphery of an amine-π-DCM system via ether bond. The H2S-mediated cleavage of NBD ether bond restored the electron-donating ability of amine and simultaneously generated an electron-donating phenol moiety, which enabled significantly strengthened π-delocalization over the D-π-A molecule skeleton of the reaction product and therefore turn-on fluorescence with tremendous contrast for H2S sensing with unprecedented sensitivity. The charge distribution calculation results of the probe molecule indicated the low electron density of the target carbon atom vulnerable to nucleophilic attack, which was expected to facilitate H2S-mediated nucleophilic substitution reaction and therefore contribute to the unprecedented response rate of the probe to H2S. The superior performance of such probe in terms of recognition specificity, biocompatibility and TPEF for bioimaging with satisfactory depth in mapping H2S level in physiological milieu was verified. The superior advantages of such probe regarding detection sensitivity and response rate as well as the preliminary in vitro experiment results regarding mapping the H2S level in liver organ unequivocally proclaimed its potential for reliable detection of highly elusive H2S species, a potential footprint for evaluating metformin-induced hepatotoxicity, and diagnosis of H2S-associated liver injury in practical applications.

Size-dependent reactivity of rhodium deuteride cluster anions Rh3Dn - (n = 0-3) toward dinitrogen: The prominent role of σ donation.

Nitrogen (N2) fixation is a challenging task for chemists. Adsorption of N2 on transition metal (TM) sites has been identified as a prerequisite for activating the very stable N≡N triple bond in both industrial and biological processes. The importance of π back-donation (filled orbitals of TM → π* orbitals of N2) between metal sites and N2 has been well elucidated while the role of another classic orbital interaction, namely σ donation (σ orbitals of N2 → empty orbitals of TM), remains ambiguous. Herein, the size-dependent reactivity of trinuclear rhodium deuteride cluster anions Rh3Dn - (n = 0-3) toward N2 adsorption in the gas phase was investigated experimentally and theoretically. A reverse relationship that higher electron-donating ability of clusters corresponds to lower N2 adsorption reactivity was experimentally observed, which is uncommon in N2 activation by gas-phase species. Theoretical analysis revealed that the σ donation rather than the π back-donation plays a predominant role in the adsorption complexes Rh3DnN2 - and the enhanced reactivity upon D addition is ascribed to the lowered energy levels of active orbitals in Rh3Dn - as n increases. This study provides the first experimental evidence to declare the important role of σ donation and new clues for the design of reactive metal species in nitrogen fixation.