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The foraging behavior of the infective juveniles (IJs) of entomopathogenic nematodes (EPNs) relies on host-derived compounds, but in a tri-trophic context, herbivore-induced root volatiles act as signals enhancing the biological control of insect pests by recruiting EPNs. In southern Chile, the EPN Steinernema australe exhibits the potential to control the raspberry weevil, Aegorhinus superciliosus, a key pest of blueberry Vaccinium corymbosum. However, there is no information on the quality of the blueberry root volatile plume or the S. australe response to these chemicals as putative attractants. Here, we describe the root volatile profile of blueberries and the chemotaxis behavior of S. australe towards the volatiles identified from Vaccinium corymbosum roots, infested or uninfested with A. superciliosus larvae. Among others, we found linalool, α-terpineol, limonene, eucalyptol, 2-carene, 1-nonine, 10-undecyn-1-ol, and methyl salicylate in root volatiles and, depending on the level of the emissions, they were selected for bioassays. In the dose–response tests, S. australe was attracted to all five tested concentrations of methyl salicylate, 1-nonine, α-terpineol, and 2-carene, as well as to 100 µg mL−1 of 10-undecyn-1-ol, 0.1 and 100 µg mL−1 of linalool, and 100 µg mL−1 of limonene, whereas eucalyptol elicited no attraction or repellency. These results suggest that some volatiles released from damaged roots attract S. australe and may have implications for the biocontrol of subterranean pests. [ABSTRACT FROM AUTHOR]

Multiwalled carbon nanotube-glassy carbon electrodes (MWCNT-GCEs) were prepared and used to immobilize 5-nitroquinoline (5-NQ), 6-nitroquinoline (6-NQ) and 8-nitroquinoline (8-NQ). Cyclic voltammetry was used to study the conventional voltammetric behavior of these NQs dissolved in an aqueous alcoholic solution and compare them with the unconventional voltammetric behavior observed when the NQs were immobilized in a porous layer of MWCNTs. Increased currents and shift to lower overpotential can be explained by the change of the mass transport regime from semi-infinite diffusion to thin layer diffusion. Reduction peak potentials depended on the position of the nitro group (-NO2 ) in the quinoline structure and the test cell pH. Reduction peak potential of -NO2 was dependent on the mesomeric effect of the resonant structures and the inductive effect of the N heteroatom. ArNO/ArNHOH redox couple was electrogenerated in situ and immobilized on a nanostructured electrode network for all the studied NQs. The redox couple generated from 5-NQ was the most stable with 50% remaining at the 15th cycle. Even though the current intensity observed for 6-NQ was the largest, the stability of 6-NQ was 35% at the same voltammetric cycle. The lowest stability was observed for 8-NQ with only 25% remaining at the 15th cycle. [ABSTRACT FROM AUTHOR]

Tetraphenylmethane-ethynylene-based shape-persistent dendrimers are a new class of nanoobjects with an intriguing 3D architecture. We report an efficient divergent strategy for their synthesis based on the Sonogashira Pd-catalyzed coupling of terminal alkynes with aryl iodides. As repeat unit, we prepared a tetraphenylmethane derivative bearing a terminal alkyne and three triazene moieties. Coupling of this building block to tetrakis(p-iodophenyl)methane afforded, after triazene activation, a dodecaiodo-terminated first generation dendrimer, which was transformed by another Sonogashira coupling into a methoxy-terminated second generation dendrimer with persistent globular shape and well-defined cavities. This work also unveils new aspects of triazene chemistry, i.e., the unprecedented efficient generation of an azo compound by mixing of a triazene with phenol. [ABSTRACT FROM AUTHOR]

In this research, we report a simple hydrothermal synthesis to prepare rhenium (Re)- doped MoS2 flower-like microspheres and the tuning of their structural, electronic, and electrocatalytic properties by modulating the insertion of Re. The obtained compounds were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Structural, morphological, and chemical analyses confirmed the synthesis of poorly crystalline Re-doped MoS2 flower-like microspheres composed of few stacked layers. They exhibit enhanced hydrogen evolution reaction (HER) performance with low overpotential of 210 mV at current density of 10 mA/cm2, with a small Tafel slope of 78 mV/dec. The enhanced catalytic HER performance can be ascribed to activation of MoS2 basal planes and by reduction in charge transfer resistance during HER upon doping. [ABSTRACT FROM AUTHOR]