Intermolecular Interactions, Morphology, and Photovoltaic Patterns in p-i-n Heterojunction Solar Cells With Fluorine-Substituted Organic Photovoltaic Materials.

During the layer-by-layer (LBL) processing of polymer solar cells (PSCs), the swelling and molecule interdiffusion are essential for achieving precise, controllable vertical morphology, and thus efficient PSCs. However, the influencing mechanism of material properties on morphology and correlated device performance has not been paid much attention. Herein, a series of fluorinated/non-fluorinated polymer donors (PBDB-T and PBDB-TF) and non-fullerene acceptors (ITIC, IT-2F, and IT-4F) are employed to investigate the performance of LBL devices. The impacts of fluorine substitution on the repulsion and miscibility between the donor and acceptor, as well as the molecular arrangement of the donor/acceptor and the vertical distribution of the LBL devices are systematically explored by the measurement of donor/acceptor Flory-Huggins interaction parameters, spectroscopic ellipsometry, and neutron reflectivity, respectively. With efficient charge transfer due to the ideal vertical and horizon morphology properties, devices based on PBDB-TF/IT-4F exhibit the highest fill factors (FFs) as well as champion power conversion efficiencies (PCEs). With this guidance, high-performance LBL devices with PCE of 17.2%, 18.5%, and 19.1% are obtained by the fluorinated blend of PBDB-TF/Y6, PBDB-TF/L8-BO, and D18/L8-BO respectively.

Tuning the Metal Ions of Prussian Blue Analogues in Separators to Enable High-Power Lithium Metal Batteries.

The Li dendrite issue is the major barrier that limits the implement of Li metal anode practically, especially at high current density. From the perspective of the nucleation and growth mechanism of the Li dendrite, we rationally develop a novel Prussian blue analogues (PBA)-derived separator, where tuning the metal ions bestows the PBAs with open metal site to confine anion movement and thereby afford a high Li+ transference number (0.78), and PBA with ordered micropores could act as an ionic sieve to selectively extract Li+ and thereby homogenize Li+ flux. This demonstrates a highly reversible Li plating/stripping cycling for 3000 h at a practically high current density (5.0 mA cm-2). Consequently, a high loading Li||LiFeO4 battery (∼10.0 mg cm-2) demonstrates ultralong cycling life at high current densities (∼5.1 mA cm-2). This work highlights the prospect of optimizing PBAs in regulating ion transport behavior to enable high-power Li metal batteries.

An Amphiphilic Molecule-Regulated Core-Shell-Solvation Electrolyte for Li-Metal Batteries at Ultra-Low Temperature.

Lithium metal batteries hold great promise for promoting energy density and operating at low temperatures, yet they still suffer from insufficient Li compatibility and slow kinetic, especially at ultra-low temperatures. Herein, we rationally design and synthesize a new amphiphilic solvent, 1,1,2,2-tetrafluoro-3-methoxypropane, for use in battery electrolytes. The lithiophilic segment is readily to solvate Li+ to induce self-assembly of the electrolyte solution to form a peculiar core-shell-solvation structure. Such unique solvation structure not only largely improves the ionic conductivity to allow fast Li+ transport and lower the desolvation energy to enable facile desolvation, but also leads to the formation of a highly robust and conductive inorganic SEI. The resulting electrolyte demonstrates high Li efficiency and superior cycling stability from room temperature to -40 °C at high current densities. Meanwhile, anode-free high-voltage cell retains 87 % capacity after 100 cycles.

Relative Local Electron Density Tuning in Metal-Covalent Organic Frameworks for Boosting CO2 Photoreduction.

The high local electron density and efficient charge carrier separation are two important factors to affect photocatalytic activity, especially for the CO2 photoreduction reaction. However, the systematic studies on the structure-functional relationship regarding the above two factors based on precisely structure model are rarely reported. Herein, as a proof-of-concept, we developed a new strategy on the evaluation of local electron density by controlling the relative electron-deficient (ED) and electron-rich (ER) intensity of monomer at a molecular level based on three rational-designed vinylene-linked sp2 carbon-covalent organic frameworks (COFs). As expected, the as-prepared vinylene-linked sp2 carbon-conjugated metal-covalent organic framework (MCOFs) (VL-MCOF-1) with molecular junction exhibited excellent activities for CO2 -to-HCOOH conversion (283.41 µmol g-1 h-1 ) and high selectivity of 97.1 %, much higher than the VL-MCOF-2 and g-C34 N6 -COF, which is due to the synergistic effect of the multi-electronic metal clusters (Cu3 (PyCA)3 ) (PyCA=pyrazolate-4-carboxaldehyde) as strong ER roles and cyanopyridine units as ED roles and active sites, as well as the boosted photo-induced charge separation efficiency of vinyl connection and increased light utilization ability. These results not only provide a strategy for regulating the electron-density distribution of photocatalysts at the molecular level but also offers profound insights for metal clusters-based COFs to effective CO2 conversion.

Rapid and Specific Enhanced Luminescent Switch of Aniline Gas by MOFs Assembled from a Planar Binuclear Cadmium(II) Metalloligand.

Due to the low vapor pressure of aniline, it is challenging to develop a specific rapid fluorescence detection material for low concentrations of aniline gas, which is suspected to result in carcinogenicity when people are exposed by ingestion, inhalation, and skin contact. Herein, the easy-preparing Schiff base ligands were employed to construct the binuclear cadmium(II) compounds featuring a good plane and fine luminescent property, and then, the end groups were changed, making the compounds metalloligands to further build the 3D metal-organic frameworks (MOFs), named MECS-2. It is found that MECS-2 can achieve specific luminescent enhancement response for aniline gas. Furthermore, a large-scale MECS-2a film could be easily prepared by electrospinning nanoMECS-2, which presents the highly efficient and visual detection for aniline gas with the luminescent enhancement effect up to 20 times and good repeatability. Our work provides a good example for the efficient construction of MOF-based films with the fluorescence detection function for organic aromatic gases.

Covalent Organic Framework Based Functional Materials: Important Catalysts for Efficient CO2 Utilization.

As hot topics in the chemical conversion of CO2 , the photo-/electrocatalytic reduction of CO2 and use of CO2 as a supporter for energy storage have shown great potential for the utilization of CO2 . However, many obstacles still exist on the road to realizing highly efficient chemical CO2 conversion, such as inefficient uptake/activation of CO2 and mass transport in catalysts. Covalent organic frameworks (COFs), as a kind of porous material, have been widely explored as catalysts for the chemical conversion of CO2 owing to their unique features. In particular, COF-based functional materials containing diverse active sites (such as single metal sites, metal nanoparticles, and metal oxides) offer great potential for realizing CO2 conversion and energy storage. This Minireview discusses recent breakthroughs in the basic knowledge, mechanisms, and pathways of chemical CO2 conversion strategies that use COF-based functional catalysts. In addition, the challenges and prospects of COF-based functional catalysts for the efficient utilization of CO2 are also introduced.

A New Ester-Substituted Quinoxaline-Based Narrow Bandgap Polymer Donor for Organic Solar Cells.

The electron-deficient ester group substitution in the sidechain of the commonly used electron-withdrawing quinoxaline (Qx) unit is seldom studied, while ester-substituted Qx units possess easy syntheses and facile modulation of the polymer solubility, and the enhanced electron-withdrawing property of ester substituted Qx unit can theoretically broaden the optical absorption of the resulting polymers and improve the open circuit voltage in the corresponding organic solar cells (OSCs). In this work, a novel ester-substituted Qx-based narrow bandgap polymer (NBG) donor material PBDTT-EFQx, which exhibits an absorption edge of 790 nm (bandgap < 1.6 eV), is designed and synthesized. Results show that the OSCs composed of PBDTT-EFQx and PC71 BM present the highest power conversion efficiency (PCE) of 6.8%, compared to PCEs of 5.0% for PBDTT-EFQx:ITIC based devices and 4.1% for PBDTT-EFQx:N2200 based devices, respectively. Characterizations and analyses indicate that the PC71 BM-based OSCs have well-matched energy levels, better complementary light absorption, the highest and most balanced carrier mobilities, as well as the lowest degree of recombination losses, and therefore, leading to the highest PCE among the three types of OSCs. This work reveals that the ester-substituted quinoxaline unit is one of the potential building blocks for NBG polymer donors.

Pronounced Dependence of All-Polymer Solar Cells Photovoltaic Performance on the Alkyl Substituent Patterns in Large Bandgap Polymer Donors.

For all-polymer solar cells which are composed of polymer donors and polymer acceptors, the effect of alkyl side chains on photovoltaic performance is a matter of some debate, and this effect remains difficult to forecast. In this concise contribution, we demonstrate that three alkyls namely branched alkyl 2-butyloctyl (2BO), long linear alkyl n-dodecyl (C12), and double-short linear alkyl n-hexyls (DC6) incorporated into the side chains of large bandgap polymer donor PBDT-TTz can induce considerable, of significance, and different electronic, optical, and morphological parameters. Systematic studies shed light on the critical role of the double-short linear alkyl n-hexyls (DC6) in (i) producing large ionization potential value, (ii) increasing propensity of the polymer to order along the π-stacking direction, (iii) generating polymer crystallites with more preferential "face-on" orientation, consequently, (iv) improvement of carriers transportation, (v) suppression of charge recombination, (vi) reduction of energy loss in all-polymer devices. In parallel, we unearth that the PBDT-TTz with double-short linear alkyl n-hexyls (DC6) represents the highest efficiency of 8.3 %, whereas, the other two PBDT-TTz analogues (2BO, C12) yield efficiencies of less than 3 % in optimized all-polymer solar cells. Though branched or long linear alkyl side chains (2BO, C12) have been applied to provide the solution processability of conjugated polymers, motifs bearing multiple short linear alkyl substituents (DC6) are proved critical to the development of high performing polymers.

MOF-derived Ni3S4 Encapsulated in 3D Conductive Network for High-Performance Supercapacitor.

Transition-metal sulfide is a good kind of material for supercapacitors because of the large capacity. Nevertheless, the low electroconductivity, slow reaction kinetics, and limited active centers lead to poor electrochemical properties such as long-term cycling stability. In the present work, nano nickel metal-organic framework (Ni-MOF) was constructed by using the nitrogen-rich functional group ligand 2,4,6-tris(3,5-dicarboxylphenylamino)-1,3,5-triazin and compounded with carbon nanotubes (CNTs) to prepare Ni-MOF/CNTs composite, which was used as a precursor to prepare the MOFs-derived NC/Ni-Ni3S4/CNTs composite with the Ni3S4 uniformly distributed in the three-dimensional (3D) conductive network. The rich nitrogen doping and 3D conductive network constructed by CNTs improved the conductivity, prompted the rapid entry of electrolyte, and improved the reaction kinetics of NC/Ni-Ni3S4/CNTs, thus obtained excellent specific capacitance, coulomb efficiency, and cyclic stability. The specific capacitance of NC/Ni-Ni3S4/CNTs is 1489.9 F/g at 1 A/g, which remains 800 F/g at 10 A/g, showing good rate performance.

One-Step Hydrothermal Synthesis of SnO2@Carbon Composites with Super Lithium Ions Storage Performances.

Tin oxide (SnO2) based anode materials for lithium ion batteries (LIBs) have drawn much attention for their high theoretical capacity and energy density, but suffer from a large volume change and resulting a rapid capacity fading during charging/discharging cycles. To optimize the status, herein, SnO2/carbon composites are synthesized using SnCl4 · 5H2O and glucose with different mass ratio as raw materials via a simple one-step hydrothermal process, following calcination under Ar gas atmosphere. As comparison, pure SnO2 is synthesized as the same as SnO2/carbon composites without glucose and calcination in air. The electrochemical impedance spectroscopy (EIS) measurements were used to investigate the lithium ions storage behavior in pure SnO2 and the SnO2@carbon composites. The EIS results indicate that pure SnO2 has much larger electronic transfer resistance and smaller diffusion coefficient of Li+ resulting worst electrochemical performances, while carbon can substantially enhance the electronic conductivity of the composites and resulting better cycle stability and rate capability of the composite anodes. Moreover, the stability and capacity of the composites are different from each other due to diverse carbon content, surface area and particle size, in which, SnO2-24%C exhibits better lithium storage performances. The initial discharge/charge capacities are up to 1650 and 890 mAh g-1 at the current density of 0.2 A g-1, and the reversible capacity even still maintains at 800 mAh g-1 after 60 cycles. The super electrochemical performances are attributed to that the proper content of carbon clusters as a support can buffer volume expansion of SnO2 during cycling, enhance the electrode conductivity and accelerate the diffusion of Li+ ions in the composite. The results implying that the composite with proper carbon content has a wide application prospect for anode material of LIBs.

Formation of N-Doped Carbon-Coated ZnO/ZnCo2 O4 /CuCo2 O4 Derived from a Polymetallic Metal-Organic Framework: Toward High-Rate and Long-Cycle-Life Lithium Storage.

Metal-organic frameworks (MOFs) are very promising self-sacrificing templates for the large-scale fabrication of new functional materials owing to their versatile functionalities and tunable porosities. Most conventional metal oxide electrodes derived from MOFs are limited by the low abundance of incorporated metal elements. This study reports a new strategy for the synthesis of multicomponent active metal oxides by the pyrolysis of polymetallic MOF precursors. A hollow N-doped carbon-coated ZnO/ZnCo2 O4 /CuCo2 O4 nanohybrid is prepared by the thermal annealing of a polymetallic MOF with ammonium bicarbonate as a pore-forming agent. This is the first report on the rational design and preparation of a hybrid composed of three active metal oxide components originating from MOF precursors. Interestingly, as a lithium-ion battery anode, the developed electrode delivers a reversible capacity of 1742 mAh g-1 after 500 cycles at a current density of 0.3 mA g-1 . Furthermore, the material shows large storage capacities (1009 and 667 mAh g-1 ), even at high current flow (3 and 10 A g-1 ). The remarkable high-rate capability and outstanding long-life cycling stability of the multidoped metal oxide benefits from the carbon-coated integrated nanostructure with a hollow interior and the three active metal oxide components.

From Metal-Organic Framework to Porous Carbon Polyhedron: Toward Highly Reversible Lithium Storage.

By application of a newly designed T-shaped ligand 5-(4-pyridin-4-yl-benzoylamino)isophthalic acid (H2PBAI) to assemble with Zn(II) ions under solvothermal conditions, a novel porous polyhedral metal-organic framework (Zn-PBAI) with pcu topology has been obtained. When treated as a precursor by annealing of Zn-PBAI at various temperatures, porous carbon polyhedra (PCP) were prepared and tested as an anode material for lithium-ion batteries. The results show that PCP carbonized at 1000 °C (PCP-1000) manifest the highest reversible specific capacity of about 1125 mAh g-1 at a current of 500 mA g-1 after 200 cycles, which is supposed to benefit from the large accessible specific area and high electric conductivity. Moreover, PCP-1000 electrode materials also exhibit superior cyclic stability and good rate capacity.

Mesoporous MnO/C-N Nanostructures Derived from a Metal-Organic Framework as High-Performance Anode for Lithium-Ion Battery.

By application of newly designed ligand 5-(3-(pyridin-3-yl)benzamido)isophthalic acid (H2PBI) to react with Mn(NO3)2 under solvothermal conditions, a 2-fold interpenetrated Mn-based metal-organic framework (Mn-PBI) with rutile-type topology has been obtained. When treated as a precursor by pyrolysis of Mn-PBI at 500 °C, mesoporous MnO/C-N nanostructures were prepared and treated as an lithium-ion battery anode. The MnO/C-N manifests good capacity of approximately 1085 mAh g-1 after 100 cycles together with superior cyclic stability and remarkable rate capacity, which is supposed to benefit from a large accessible specific area and unique nanostructures. The remarkable performances suggest promising application as an advanced anode material.

Lead-Based Metal-Organic Framework with Stable Lithium Anodic Performance.

A microporous Pb-based metal-organic framework (MOF) [Pb(4,4'-ocppy)2]·7H2O (Pb-MOF) has been constructed from 4-(4-carboxyphenyl)pyridine N-oxide and Pb(NO3)2. Structural analysis reveals that the Pb-MOF possesses three-dimensional framework with a one-dimensional rhombic channel. When tested as a lithium-ion battery anode, a reversible lithium storage capacity of 489 mAh g-1 was maintained after 500 cycles at 100 mA g-1 as well as excellent cycling stability. The superior electrochemical performance may be derived from the sustenance of the Pb-MOF framework and compositional features of the organic moiety.

A Molecular Chameleon with Fluorescein and Rhodamine Spectroscopic Behaviors.

A new class of fluorescein/rhodamine hybrids with two spirolactone rings was reported to exhibit dual-output fluorescent behaviors independently. Isolation and characterization for two diastereomers, trans-RhOH and cis-RhOH, have been made and their X-ray crystal structures determined. In a basic environment, the spirolactone ring on the hydroxyl side will be opened to give a fluorescein-like optical output with the lowest absorptions at 485 and 530 nm emission. On the other hand, a rhodamine-like optical output, i.e., 528 nm absorption and 575 nm emission, will be switched on by a H(+) or a Hg(2+) ion, attributed to the spirolactone ring opening on the amino side. In a methanol-buffer system with different pH values, the corresponding pKa values for the hydroxyl and amino groups were determined as 5.7 and 2.3, respectively. Selective Hg(2+)-sensing properties have also been discussed, and log Ks values of about 3.60 and 3.73 were determined. Confocal microscopic images of Caenorhabditis elegans incubated with RhOH were found to show enhanced fluorescent intensity with a Hg(2+) ion, demonstrating the potential application of RhOH for in vivo biological imaging.

Lithium-Ion-Battery Anode Materials with Improved Capacity from a Metal-Organic Framework.

We present a porous metal-organic framework (MOF) with remarkable thermal stability that exhibits a discharge capacity of 300 mAh g(-1) as an anode material for a lithium-ion battery. Pyrolysis of the obtained MOF gives an anode material with improved capacity (741 mAh g(-1)) and superior cyclic stability.

(-)-Epicatechin-3-gallate (a polyphenol from green tea) potentiates doxorubicin-induced apoptosis in H9C2 cardiomyocytes.

OBJECTIVE: The effect of epicatechin-3-gallate (ECG), a polyphenol that is present in green tea, on doxorubicin (DOX) cytotoxicity in H9C2 cardiomyocytes and its underlying mechanisms were investigated. RESULTS: Pretreatment with ECG (20 and 30 µM) significantly increased DOX-induced apoptosis to 16-18% in H9C2 cardiomyocytes. The Bax/Bcl-2 ratio increased significantly after 1 h pretreatment with ECG. ECG also enhanced the phosphorylation of AMP-activated protein kinase (AMPK) which was induced by DOX in a dose-dependent manner. CONCLUSION: Pretreatment with ECG sensitized H9C2 cells to DOX-mediated apoptosis through modulation of proteins involved in apoptosis and AMPK.

High doses of (-)-epigallocatechin-3-gallate from green tea induces cardiac fibrosis in mice.

OBJECTIVE: Tea is the most consumed beverage in the world. (-)-Epigallocatechin-3-gallate (EGCG), a major green tea polyphenol, is effective in the prevention of several chronic diseases, and is marketed as part of many dietary supplements. We have now examined the myocardiotoxic effect of high doses of EGCG in mice. RESULTS: EGCG (500 and 1000 mg/kg·d) induced cardiac collagen synthesis and fibrosis-related protein expression, such as connective tissue growth factor (CTGF) and fibronectin (FN) in mice. Moreover, EGCG decreased the protein expression of p-AMPK and increased the levels of p-p70S6 K and p-S6. CONCLUSION: This is the first evidence that high oral doses of EGCG could induce cardiac fibrosis, and shed new light on the understanding of EGCG-mediated myocardiotoxicity.

Anion-dependent assembly of four sensitized near-infrared luminescent heteronuclear Zn(II)-Yb(III) Schiff base complexes from a trinuclear Zn(II) complex.

Four anion-dependent 0D Zn(II)-Yb(III) heterometallic Schiff base complexes, [YbZn2L2(OAc)4]·ClO4 (2), YbZnL2(NO3)3 (3), [(YbL)2(H2O)Cl(OAc)]2·[ZnCl4]2 (4), and YbZnL(OAc)4 (5), were assembled through central metal substitution or reconstruction from homotrinuclear Zn(II) complex {[(Zn(OAc)(H2O)L]2Zn}(ClO4)2·4H2O [1; HL = 2-ethoxy-6-[(pyridin-2-ylmethylimino)methyl]phenol] with different Yb(III)X3 salts [X = ClO4 (2), NO3 (3), Cl (4), and OAc (5)], in which the Zn(II)-sensitized near-infrared luminescent performances in the four complexes 2-5 are closely related to their structural models.

Chiral BINOL-phosphate assembled single hexagonal nanotube in aqueous solution for confined rearrangement acceleration.

Creating microenvironments that mimic an enzyme's active site is a critical aspect of supramolecular confined catalysis. In this study, we employ the commonly used chiral 1,1'-bi-2-naphthol (BINOL) phosphates as subcomponents to construct supramolecular hollow nanotube in an aqueous medium through non-covalent intermolecular recognition and arrangement. The hexagonal nanotubular structure is characterized by various techniques, including X-ray, NMR, ESI-MS, AFM, and TEM, and is confirmed to exist in a homogeneous aqueous solution stably. The nanotube's length in solution depends on the concentration of chiral BINOL-phosphate as a monomer. Additionally, the assembled nanotube can accelerate the rate of the 3-aza-Cope rearrangement reaction by up to 85-fold due to the interior confinement effect. Based on the detailed kinetic and thermodynamic analyses, we propose that the chain-like substrates are constrained and pre-organized into a reactive chair-like conformation, which stabilizes the transition state of the reaction in the confined nanospace of the nanotube. Notably, due to the restricted conformer with less degrees of freedom, the entropic barrier is significantly reduced compared to the enthalpic barrier, resulting in a more pronounced acceleration effect.