Low Contact Resistance Organic Single-Crystal Transistors with Band-Like Transport Based on 2,6-Bis-Phenylethynyl-Anthracene.

Contact resistance has become one of the main bottlenecks that hinder further improvement of mobility and integration density of organic field-effect transistors (OFETs). Much progress has been made in reducing contact resistance by modifying the electrode/semiconductor interface and decreasing the crystal thickness, however, the development of new organic semiconductor materials with low contact resistance still faces many challenges. Here, 2,6-bis-phenylethynyl-anthracene (BPEA) is found, which is a material that combines high mobility with low contact resistance. Single-crystal BEPA OFETs with a thickness of ≈20 nm demonstrated high mobility of 4.52 cm2  V-1  s-1 , contact resistance as low as 335 Ω cm, and band-like charge transport behavior. The calculated compatibility of the EHOMO of BPEA with the work function of the Au electrode, and the decreased |EHOMO -ΦAu | with the increase of external electric field intensity from source to gate both contributed to the efficient charge injection and small contact resistance. More intriguingly, p-type BPEA as a buffer layer can effectively reduce the contact resistance, improve the mobility, and meanwhile inhibit the double-slope electrical behavior of p-channel 2,6-diphenyl anthracene (DPA) single-crystal OFETs.

Novel Cyclopenta[c]pyridine Derivatives Based on Natural Cerbinal as Potential Agrochemical Anti-TMV Agents and Insecticides.

Based on natural cerbinal, a series of novel 4-bit modified cyclopenta[c]pyridine derivatives containing a substituted amide or ester moiety were designed and synthesized for the first time. Their structures were systematically characterized by NMR and high-resolution mass spectra (HRMS). The anti-TMV activities, such as protection, inactivation, and curative effects in vivo, were evaluated methodically. The lethal activities of the target compounds against the agriculturally common pests Plutella xylostella larvae and Aphis laburni kaltenbach were evaluated by the immersion method. The bioassay results indicated that most of the target compounds exhibited good to excellent anti-TMV activity levels, good lethal activity against P. xylostella larvae at 600 µg/mL, and greater insecticidal activities against A. laburni Kaltenbach compared to the plant-derived insecticide rotenone. The binding mode of cerbinal and cyclopenta[c]pyridine derivatives 4b, 4p, and 4v with the TMV protein was studied with a molecular docking method, which indicated that the functional group of the 2- and 4-positions is vital for anti-TMV activity. The systematic research provides strong evidence that these novel 4-bit modified cyclopenta[c]pyridine derivatives could become potential agrochemical insecticides and anti-TMV agents.

On-Off Ratiometric Fluorescence Europium(III) Metal-Organic Framework for Quantitative Detection of the Inflammatory Marker Neopterin.

Benefiting from the unique photoluminescence behavior of the lanthanide(III) ions and organic ligands, a lanthanide(III) metal-organic framework (Ln-MOF) material can simultaneously demonstrate photoluminescence of lanthanide(III) cations and organic molecules and endow its superior applications of fluorescence sensing behaviors. Herein, we present a europium(III) MOF material {[Eu2(BPTA)·(CH3COO)2·3DMA]·0.5DMA·3H2O}n (1) (where H4BPTA is 3,3',5,5'-biphenyltetracarboxylic acid) for photoluminescence performance of quantitatively sensing the inflammatory marker neopterin (Neo). The obtained 1 comprises Eu2(COO)4 paddlewheel secondary building units, which could be bridged by BPTA4- ligands to extend a 2D framework. The fluorescence titration indicates 1 can achieve simultaneous fluorescence behavior of Eu3+ ions and Neo via on-off ratiometric effects and thus could be exploited as the ratiometric fluorescence sensor matrix. Such a fluorescence phenomenon of 1 as a ratiometric sensor for quantitative detection of Neo via an on-off ratiometric effect is never observed in MOF chemistry. Moreover, naked-eye visible color variations of the fluorescence for 1 could be observed from red to blue with increasing concentrations of Neo, confirmed by fluorescent test strips as well as portable fluorescent hydrogels. And 1 also shows a low detection limit of 15.11 nM. A synergetic contribution of the competitive absorption, fluorescence resonance energy-transfer, and photoinduced electron-transfer mechanisms between Neo and the framework of 1 realizes the on-off ratiometric fluorescence behavior for Neo detection, supported by the UV-vis spectral overlap experiment and DFT calculations.

Ratiometric Fluorescence Thermometry, Quantitative Gossypol Detection, and CO2 Chemical Fixation by a Multipurpose Europium (III) Metal-Organic Framework.

A lanthanide-based molecular crystalline material endows metal-organic frameworks (MOFs) with many fascinating applications such as fluorescence detection and CO2 chemical fixation. Herein, we describe and study a multipurpose europium(III) MOF with the formula of {[Eu2(TATAB)2]·2.5H2O·2DMF}n (Eu-MOF) (where H3TATAB is 4,4',4″-((1,3,5-triazine-2,4,6-triyl)tris(azanediyl))tribenzoic acid ligand) for photoluminescence sensor matrix and CO2 chemical fixation. This Eu-MOF features 1D square channels along the c direction with a pore size of ca.14.07 Å × 14.07 Å, occupied by lattice water and DMF molecules. The obtained Eu-MOF can achieve simultaneous luminescence of the H3TATAB ligand and Eu3+ ions, which can be developed as the sensor matrix for ratiometric fluorescence thermometry. The luminescence of the Eu-MOF demonstrates an obvious color change from red to yellow as temperature rises from 303 to 373 K and the Eu-MOF has a satisfying relative sensitivity of 3.21% K-1 and a small temperature uncertainty of 0.0093 K at 333 K. Moreover, sensitive detection of gossypol was achieved with a quenching constant Ksv of 1.18 × 105 M-1 and a detection limit of 4.61 µM. A combination of the competitive absorption and photoinduced electron transfer caused by host-guest interactions and strengthened π-π packing effect synergistically between gossypol molecules and the Eu-MOF skeleton realizes the "turn-off" sensing of gossypol. Importantly, the nature of the Eu-MOF allows showing CO2 chemical fixation under mild conditions. Thus, the Eu-MOF can be utilized as a multipurpose material for ratiometric fluorescence thermometry, quantitative gossypol detection, and CO2 chemical fixation.

A turn-on fluorescent Zn(II) metal-organic framework sensor for quantitative anthrax biomarker detection.

2,6-Pyridine dicarboxylic acid (DPA) is considered one of the main anthrax biomarkers, and the detection of DPA is of great significance. This work presents a Zn(II)-based metal-organic framework (MOF) with the formula {[Zn2(2,6-NBC)2(vlpy)Zn(2,6-NBC)(vlpy)0.5]·0.8(2,6-H2NBC)·H2O}n (1) assembled from 2,6-naphthalenedicarboxylic acid (2,6-H2NBC) and 4,4'-vinylenedipyridine (vlpy) for a photoluminescence sensor matrix for DPA detection. 1 features a 3D pillar-layer framework with nanopore sizes of ca.13.165 Å × 12.731 Å, 12.725 Å × 11.018 Å and 13.114 Å × 13.165 Å along the three directions, occupied by lattice water and disordered 2,6-H2NBC molecules. The obtained 1 can be used as a turn-on fluorescence sensor for the detection of DPA with high selectivity, excellent sensitivity and recyclability. The luminescence of 1 demonstrates an obvious color change from blue to purplish blue as the DPA concentration rises. Furthermore, a linear correlation is presented between the fluorescence and a low DPA concentration of 0-0.3 mM, and the detection limit can reach as low as 128 nM, much lower than that of an infectious dose to a human of anthrax spores (60 µM). A fluorescence test paper is fabricated to detect DPA rapidly through color change. DFT calculations indicate the intermolecular photoinduced electron-transfer transition and hydrogen-bonding interaction between DPA molecules and the skeleton of 1 induces the "turn-on" fluorescence sensing of DPA behavior.

Preparation and Anti-Tobacco Mosaic Virus Activities of Crocetin Diesters.

The development of antiviral agents with an original structure and noticeable effect is always in great need. Natural products are important lead compounds in the development of new pesticides. Crocin-1 and crocin-2 were effectively isolated from Gardeniae fructus and found to have higher anti-tobacco mosaic virus (TMV) activity levels than ribavirin. A series of the crocetin diester derivatives were synthesized with separated crocetin-1 as material and evaluated for their anti-TMV activities. They could be dissolved in common organic solvents as dichloromethane, ethyl acetate, tetrahydrofuran, and methanol. Compounds 5, 9, 13, 14, and 15 displayed higher activities in vivo than ribavirin. Compound 14 with significantly higher antiviral activities than lead compounds (crocin-1 and crocin-2) emerged as a new antiviral candidate.

Ti-Oxo Clusters with Peripheral Alkyl Groups as Cathode Interlayers for Efficient Organic Solar Cells.

Three independent Ti-oxo clusters (TOCs) that contain 6, 8, and 12 Ti atoms in the cores and alkyl groups on the surface were developed as cathode interlayers in bulk-heterojunction organic solar cells (OSCs). These TOCs have precise chemical structures with a single crystal, excellent solubility in methanol, and well-aligned work function. Smooth films can be facilely obtained by spin-casting their solution on top of the active layer. Therefore, they can be used as an interlayer in OSCs to provide a high power conversion efficiency (17.29%). Further studies reveal that these TOCs can not only reduce the work function of the silver electrode to provide better energy level alignment but also exhibit a significant n-doping effect with the non-fullerene acceptors to facilitate efficient electron extraction and transport. Our results demonstrate that TOCs as semiconductors have great potential application in OSCs.

Fullerene as an additive for increasing the efficiency of organic solar cells to more than 17.

In this work, we introduced a fullerene acceptor (PC71BM) into the binary photo-active layer based on a polymer donor (PM6) and a non-fullerene small molecular acceptor (BTP-BO-4Cl), and as a consequence, the ternary organic solar cells realized a high-power conversion efficiency of 17.39% compared to 16.65% in binary solar cells. The performance enhancement was found to be due to the optimized morphology and hence balanced hole and electron mobilities, which is responsible for the suppressed charge recombination and hence high photocurrent in solar cells. In addition, PC71BM shows the complementary absorption with PM6 and BTP-BO-4Cl, which can broaden the absorption range of the photo-active layer and hence more photons from the sunlight can be utilized. Besides, PC71BM shows the cascade energy level alignment between PM6 and BTP-BO-4Cl, which is helpful for charge transfer from donor to acceptor. All these merits explain the high performance in ternary solar cells, and also demonstrate that ternary photovoltaics adopting non-fullerene acceptor with the fullerene acceptor as small amount of additive is an efficient strategy to gain high performing organic solar cells.

An Organic-Inorganic Hybrid Electrolyte as a Cathode Interlayer for Efficient Organic Solar Cells.

An organic-inorganic hybrid electrolyte based on a cyclic Ti-oxo cluster as the inorganic core and naphthalene-based organic ammonium bromide salts as the electrolyte was developed with easy synthesis and low cost. The new hybrid electrolyte exhibits excellent solubility in methanol, aligned work function, good conductivity, and amorphous state in thin film, enabling its successful application as a cathode interlayer in organic solar cells with a high power conversion efficiency of 17.19 %. This work demonstrates that the hybrid electrolytes are a new kind of semiconductor, exhibiting promising applications in organic electronics.

Synthesis and Anti-Tobacco Mosaic Virus/Fungicidal/Insecticidal/Antitumor Bioactivities of Natural Product Hemigossypol and Its Derivatives.

To further study the structure-activity relationship of gossypol, hemigossypol (1) and its derivatives (2-23) were successfully designed via structure simplification and chemically synthesized. The anti-tobacco mosaic virus (TMV), fungicidal, and insecticidal activities of them were tested systematically. Most of these derivatives exhibited excellent anti-TMV activity. Furthermore, these compounds also exhibited broad-spectrum fungicidal activities against 14 kinds of phytopathogenic fungi. In particular, hemigossypol acid lactone (7) was stable in the air. In terms of biological activity, it not only showed anti-TMV activity (inhibitory rates of 70.3, 65.4 and 72.4% at 500 µg/mL for inactivation, curative, and protection activity in vivo, respectively) comparable to ningnanmycin but also exhibited higher insecticidal activity against mosquito larvae (60%/0.25 mg/kg) than the commercial species rotenone. None of hemigossypol and the tested derivatives showed antitumor activities.

Evaluation of different potassium salts as activators for hierarchically porous carbons and their applications in CO2 adsorption.

KOH is one of the most widely used activators for the synthesis of highly porous carbon. However, the strong causticity of KOH could cause serious equipment damage and safety issues at high temperature. In the current work, we presented the synthesis of porous carbons with large surface area using four different potassium salts (CH3COOK, KHCO3, K2CO3, and K2C2O4·H2O) as mild but effective activators. Hydrochar prepared from the hydrothermal carbonization of glucosamine hydrochloride was used as carbon precursor. The carbons exhibited specific surface area up to 2403 m2/g. In order to reveal the different influences of nitrogen doping and textural properties under low and high pressure conditions, CO2 adsorption was tested with pressure up to 20 bar. At 1 bar, ultramicropore was the most determinant factor. Nitrogen doping also showed important influences, especially on the CO2/N2 selectivity. At 20 bar, the carbon activated by KHCO3 showed CO2 uptakes of 26.24 (0 °C) and 18.63 mmol/g (25 °C). The experiment results indicated that the uptake at 20 bar correlated with the total surface area and total porosity of the carbon, and no apparent effects from nitrogen doping were observed.

A Novel Perspective of the Kalman Filter from the Rényi Entropy.

Rényi entropy as a generalization of the Shannon entropy allows for different averaging of probabilities of a control parameter α. This paper gives a new perspective of the Kalman filter from the Rényi entropy. Firstly, the Rényi entropy is employed to measure the uncertainty of the multivariate Gaussian probability density function. Then, we calculate the temporal derivative of the Rényi entropy of the Kalman filter's mean square error matrix, which will be minimized to obtain the Kalman filter's gain. Moreover, the continuous Kalman filter approaches a steady state when the temporal derivative of the Rényi entropy is equal to zero, which means that the Rényi entropy will keep stable. As the temporal derivative of the Rényi entropy is independent of parameter α and is the same as the temporal derivative of the Shannon entropy, the result is the same as for Shannon entropy. Finally, an example of an experiment of falling body tracking by radar using an unscented Kalman filter (UKF) in noisy conditions and a loosely coupled navigation experiment are performed to demonstrate the effectiveness of the conclusion.

Thieno[3,4-c]pyrrole-4,6-dione-based conjugated polymers for organic solar cells.

Conjugated polymers consisting of electron-rich and electron-deficient units as alternative structures have played important roles in the field of organic solar cells (OSCs). A thieno[3,4-c]pyrrole-4,6-dione (TPD) unit as an electron-deficient unit has been used to construct conjugated polymers for application in fullerene and non-fullerene based OSCs. TPD-based monomers can be simply prepared and TPD-polymers can be synthesized via environmentally friendly direct (hetero)arylation polymerization, providing a possibility for large quantity preparation. TPD-polymers usually have deep frontier energy levels, wide band gaps with absorption onset around 700 nm and good charge transport properties, showing the advantages of high open-circuit voltage, high fill-factor and excellent spectral matching with a small band gap non-fullerene acceptor. From the material design and synthesis and their optoelectrical properties, TPD-polymers have great potential applications in OSCs toward large-area devices. In this review, we provide an overview of TPD-polymers for OSCs in the last ten years, including the design and synthesis of TPD-polymers, and their application in fullerene and non-fullerene OSCs. We will also provide some perspective about the research of TPD-polymers that meet the requirement of OSCs. We hope that our universal summary can stimulate the study of TPD-polymers in the future, especially toward high performance, low cost and stable OSCs.

Natural Product Cerbinal and Its Analogues Cyclopenta[c]pyridines: Synthesis and Discovery as Novel Pest Control Agents.

Owing to the changing needs of agriculture, the exploration of new pest control agents remains as critical as ever. The analogues 3a-3v of the natural product cerbinal were synthesized from genipin by an efficient and practical method under additive-free conditions. The antiviral and insecticidal effects of cerbinal and these cyclopenta[c]pyridines (3a-3v) were evaluated systematically. Most of the synthesized compounds exhibited higher anti-TMV activities than the lead compound cerbinal. Compound 3s (2-(4-methoxyphenyl)) had the most promising inhibitory activities against TMV (inactivation effect 49.0 ± 0.8%, curative effect 41.2 ± 4.3%, and protection effect 51.5 ± 2.7% at 500 µg/mL). Among the synthesized compounds, only 3v (2-(2-chloro-4-(trifluoromethoxy)phenyl)) reached the activity level of cerbinal against Plutella xylostella. This suggested that the cyclopenta[c]pyridines obtained by modifications of cerbinal at position 2 are very significant for the anti-TMV activity, and yet were exceptionally less active for the insecticidal activities.

A Non-Linear Filtering Algorithm Based on Alpha-Divergence Minimization.

A non-linear filtering algorithm based on the alpha-divergence is proposed, which uses the exponential family distribution to approximate the actual state distribution and the alpha-divergence to measure the approximation degree between the two distributions; thus, it provides more choices for similarity measurement by adjusting the value of α during the updating process of the equation of state and the measurement equation in the non-linear dynamic systems. Firstly, an α -mixed probability density function that satisfies the normalization condition is defined, and the properties of the mean and variance are analyzed when the probability density functions p ( x ) and q ( x ) are one-dimensional normal distributions. Secondly, the sufficient condition of the alpha-divergence taking the minimum value is proven, that is when α ≥ 1 , the natural statistical vector's expectations of the exponential family distribution are equal to the natural statistical vector's expectations of the α -mixed probability state density function. Finally, the conclusion is applied to non-linear filtering, and the non-linear filtering algorithm based on alpha-divergence minimization is proposed, providing more non-linear processing strategies for non-linear filtering. Furthermore, the algorithm's validity is verified by the experimental results, and a better filtering effect is achieved for non-linear filtering by adjusting the value of α .

A Simple, Small-Bandgap Porphyrin-Based Conjugated Polymer for Application in Organic Electronics.

A simple, small-bandgap porphyrin-based conjugated polymer with ethylnyl linkers is prepared for application in organic electronics. Beneficial from quinoid resonance form, the polymer showed near-infrared absorption up to 1000 nm and strong photoluminescence emission with a quantum yield of 0.2%. The polymer can be successfully applied to several electronic devices, such as organic field-effect transistors with ambipolar charge transport, organic solar cells with a high external quantum efficiency of 0.58 at 970 nm, and organic photodetectors with high responsibility and detectivity.

Two luminescent lanthanide(iii) metal-organic frameworks as chemosensors for high-efficiency recognition of Cr(vi) anions in aqueous solution.

Two new lanthanide(iii) metal-organic frameworks (MOFs) {[(CH3)2NH2]2[Ln4(FDA)7(DMF)2]·0.5DMF}n [Ln = Eu (1), and Tb (2)] based on furan-2,5-dicarboxylic acid (H2FDA) have been successfully assembled and well characterized in detail. These MOFs are isostructural and demonstrate 12-connected sqc15 topologies, which are rarely observed in MOF chemistry, especially in lanthanide(iii) MOFs. Moreover, these two MOFs could show a tolerance towards moisture and organic solvents and satisfactory chemical stabilities. More importantly, they exhibit sensitive and selective luminescence quenching response towards Cr2O72- and CrO42- anions in aqueous solution with the average quenching Ksv values of 1.25 × 104 L mol-1 (Cr2O72-) and 3.56 × 103 L mol-1 (CrO42-) for 1 and 1.46 × 104 L mol-1 (Cr2O72-) and 4.35 × 103 L mol-1 (CrO42-) for 2 and the detection limits of 1.14 × 10-4 mol L-1 (Cr2O72-) and 1.12 × 10-4 mol L-1 (CrO42-) for 1 and 7.42 × 10-5 mol L-1 (Cr2O72-) and 1.27 × 10-4 mol L-1 (CrO42-) for 2. The high quenching Ksv values and low detection limits make them more feasible in sensing Cr(vi) anions in aqueous solution. The possible detection mechanism has been discussed in detail.

Tuning the luminescence of two 3d-4f metal-organic frameworks for the fast response and highly selective detection of aniline.

Two 3D solvent-stable zinc(ii)-lanthanide(iii) heterometallic metal-organic frameworks (MOFs) {[(CH3)2NH2]2[Zn2Ln2(FDA)6(DMF)2]·2DMF}n [Ln = Eu (Zn-Eu) and Tb (Zn-Tb); H2FDA = furan-2,5-dicarboxylic acid] based on Zn2Ln2(COO)10 tetrametallic clusters and furan-2,5-dicarboxylic acid have been successfully synthesized. These MOFs can serve as luminescent sensors for the fast response and highly selective detection of aniline via luminescence quenching. More importantly, a linear correlation is observed between their luminescence and the low concentration of aniline and the detection limits of aniline are 7.5 µmol L-1 for Zn-Eu and 5.2 µmol L-1 for Zn-Tb.

Temperature-induced phase changes in bismuth oxides and efficient photodegradation of phenol and p-chlorophenol.

A novel, simple and efficient approach for photodegrading phenol and p-chlorophenol, based on BixOy, was reported for the first time. Monoclinic Bi2O4 was prepared by the hydrothermal treatment of NaBiO3·2H2O. A series of interesting phase transitions happened and various bismuth oxides (Bi4O7, ß-Bi2O3 and α-Bi2O3) were obtained by sintering Bi2O4 at different temperatures. The results demonstrated that the Bi2O4 and Bi4O7 phase had strong abilities towards the oxidative decomposition of phenol and p-chlorophenol and very high rates of TOC removal were observed. The characterization by XRD and XPS revealed that Bi(4+) in Bi2O4 and Bi(3.5+) in Bi4O7 were reduced to Bi(3+) during the reaction process. Singlet oxygen ((1)O2) was identified as the major reactive species generated by Bi2O4 and Bi4O7 for the photodegradation of p-chlorophenol and phenol. This novel approach could be used as a highly efficient and green technology for treating wastewaters contaminated by high concentrations of phenol and chlorophenols.