Plants can defend themselves to pathogen and herbivore attack by responding to chemical signals that are emitted by attacked plants. It is well established that such signals can be transferred through the air. In theory, plants can also communicate with each other through underground common mycorrhizal networks (CMNs) that interconnect roots of multiple plants. However, until now research focused on plant-to-plant carbon nutrient movement and there is no evidence that defense signals can be exchanged through such mycorrhizal hyphal networks. Here, we show that CMNs mediate plant-plant communication between healthy plants and pathogen-infected tomato plants (Lycopersicon esculentum Mill.). After establishment of CMNs with the arbuscular mycorrhizal fungus Glomus mosseae between tomato plants, inoculation of ‘donor’ plants with the pathogen Alternaria solani led to increases in disease resistance and activities of the putative defensive enzymes, peroxidase, polyphenol oxidase, chitinase, β-1,3-glucanase, phenylalanine ammonia-lyase and lipoxygenase in healthy neighbouring ‘receiver’ plants. The uninfected ‘receiver’ plants also activated six defence-related genes when CMNs connected ‘donor’ plants challenged with A. solani. This finding indicates that CMNs may function as a plant-plant underground communication conduit whereby disease resistance and induced defence signals can be transferred between the healthy and pathogen-infected neighbouring plants, suggesting that plants can ‘eavesdrop’ on defence signals from the pathogen-challenged neighbours through CMNs to activate defences before being attacked themselves.

Asymmetric photoredox catalysis offers exciting opportunities to develop new synthetic approaches to chiral molecules through novel reaction pathways. Employing the first-row transition metal complexes as the chiral photoredox catalysts remains, however, a formidable challenge, although these complexes are economic, environmentally friendly, and often exhibit special reactivities. We report in this Article the development of one class of highly efficient asymmetric/photoredox bifunctional catalysts based on the copper­(II) bisoxazoline complexes (CuII–BOX) for the light-induced enantioselective alkylation of imines. The reactions proceed under very mild conditions and without a need for any other photosensitizer. The simple catalytic system and readily tunable chiral ligands enable a significantly high level of enantioselectivity for the formation of chiral amine products bearing a tetrasubstituted carbon stereocenter (36 examples, up to 98% ee). Overall, the CuII–BOX catalysts initiate the radical generation, and also govern the subsequent stereoselective transformations. This strategy utilizing chiral complexes comprised of a first-row transition metal and a flexible chiral ligand as the asymmetric photoredox catalysts provides an effective platform for the development of green asymmetric synthetic methods.

This work provides a novel approach to improve the fouling resistance of PVDF membrane. An amphiphilic graft copolymer (PVDF-g-PACMO) having poly(vinylidene fluoride) (PVDF) backbones and polyacryloylmorpholine (PACMO) side chains was synthesized using the radical polymerization method, and then the copolymer was cast into a flat membrane via immersion phase inversion. The results indicate that the PACMO chain was successfully grafted onto PVDF main chains, and the grafting degree of PACMO in PVDF-g-PACMO copolymer increases with the increase of the monomer concentration in reaction solution. The structure and performance of as-prepared membranes were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), contact angle measurement, static protein adsorption, and filtration experiments. It is found that a higher grafting degree of PACMO endows the copolymer membrane with larger membrane surface micropores and a better hydrophilicity. The improved hydrophilicity provides the copolymer membrane with the resistance of protein adsorption to the membrane surface and a high flux recovery.

α-Amino acids are essential for life as building blocks of proteins and components of diverse natural molecules. In both industry and academia, the incorporation of unnatural amino acids is often desirable for modulating chemical, physical, and pharmaceutical properties. We here report a protocol for the economical and practical synthesis of optically active α-amino acids based on an unprecedented stereocontrolled 1,3-nitrogen shift. Our method employs abundant and easily accessible carboxylic acids as starting materials, which are first connected to a nitrogenation reagent, followed by a highly regio- and enantioselective ruthenium- or iron-catalyzed C( sp 3 )−H amination. This straightforward method displays a very broad scope, providing rapid access to optically active α-amino acids with aryl, allyl, propargyl, and alkyl side chains, and also permits stereocontrolled late-stage amination of carboxylic acid-containing drugs and natural products.

The enantioselective photoredox reaction of α,β-unsaturated carbonyl compounds and tertiary/secondary α-silylamines was enabled by a readily available single NiII–DBFOX catalyst under visible light conditions.

As a new class of multifunctional materials, photochromic materials have received much attention due to their potential applications in many fields. In order to investigate the effect of anions on the electron-transfer properties of photochromic coordination polymers, five bipyridinium-based complexes with different anions, namely [Zn­(bcbpy)­(H2O)­(Cl)]·Cl·2H2O (1), [Zn­(bcbpy)­(H2O)­(Br)]·Br·2H2O (2), [Zn­(bcbpy)2]·2I·6H2O (3), [Zn­(bcbpy)2]·2ClO4·6.4H2O (4), and [Zn­(bcbpy)­(N3)2]·3H2O (5) (H2bcbpy·2Cl = 1,1′-bis­(3-carboxylatobenzyl)-4,4′-bipyridinium dichloride), were synthesized via self-assembly and were characterized by IR spectroscopy, elemental analysis, thermogravimetric analysis, and single-crystal X-ray diffraction. Due to different charge transfer interactions between the anions and the electron-deficient bipyridinium moiety, these complexes exhibit different electron-transfer photochromic behaviors. Specifically, complexes 1, 2, 4, and 5 were photochromic but 3 was not. This difference could be attributed to a stronger charge transfer interaction in complex 3 in comparison to complexes 1, 2, 4, and 5, as well as the heavy-atom effect of iodine. It is expected that this study will provide a new perspective for the rational design and synthesis of novel photochromic materials.

Biofouling of membrane surfaces by the attachment of microorganisms is one of the major obstacles for ensuring the effectiveness of membrane separation processes. This work presents the construction of a zwitterionic PVDF membrane surface with improved resistance to biofouling. An amphiphilic copolymer of poly(vinylidene fluoride)-graft-poly(N,N-dimethylamino-2-ethylmethacrylate) (PVDF-g-PDMAEMA) was first synthesized via radical graft copolymerization and then the flat membrane was cast with immersed phase inversion. The PDMAEMA side chains tended to aggregate on the membrane surface, pore surface and internal pore channel surface, and were converted with 1,3-propane sultone (1,3-PS) to yield a zwitterionic membrane surface. A higher conversion of PDMAEMA chains and distribution of zwitterions were obtained using a longer treatment time. A biofouling assay indicated that incorporation of zwitterions suppressed the adsorption of extracellular polymer substances and the adhesion of Escherichia coli bacterial cells to the membrane surface, endowing the membrane with a high flux recovery and biofouling resistance in the filtration process.

The high ratio of pyridinic and pyridone N-doped graphene sheets have been synthesized by functionalizing graphene oxide (GO) with different oxygen groups on its surface. The typical N-doped graphene was determined to be ~3–5 layers by transmission electron microscopy (TEM) and atomic force microscopy (AFM), and the nitrogen content was measured as 6.8–8 at. % by X-ray photoelectron spectroscopy (XPS). The structure of the N-doped graphene with different surface functional groups was characterized by Raman spectroscopy. The research result indicates that the carboxylation of GO is the key factor to obtain pyridinic and pyridone N types during the N atom doping process. Compared to general N-doped graphene, the electrochemical test shows that specific capacitance of the GO-OOH-N sample reaches up to 217 F/g at a discharge current density 1 A/g and stable cycling performance (keep 88.8 % specific capacitance after 500 cycles at the same discharge current density) when applied to the supercapacitor electrode materials.Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-015-1031-z) contains supplementary material, which is available to authorized users.