N-Heterocyclic Carbene-Derived 1,3,5-Trimethylenebenzene: On-Surface Synthesis and Electronic Structure.

1,3,5-Trimethylenebenzene (1,3,5-TMB), a 3-fold-symmetric triradical with a high-spin ground state, is an attractive platform for investigating the unique spin properties of π-conjugated triangular triradicals. Here, we report the on-surface synthesis of N-heterocyclic carbene (NHC)-derived 1,3,5-TMB (N-TMB) via surface-assisted C-C and C-N coupling reactions on Au(111). The chemical and electronic structures of N-TMB on the Au(111) surface are revealed with atomic precision using scanning tunneling microscopy and noncontact atomic force microscopy, combined with density functional theory (DFT) calculations. It is demonstrated that there is substantial charge transfer between N-TMB and the substrate, resulting in a positively charged N-TMB on Au(111). DFT calculations at the UB3LYP/def2-TZVP level of theory and multireference method, e.g., CASSCF/NEVPT2, indicate that N-TMB possesses a doublet ground state with reduced Cs symmetry in the gas phase, contrasting the quartet ground state of 1,3,5-TMB with D3h symmetry, and exhibits a doublet-quartet energy gap of -0.80 eV. The incorporation of NHC structures and the extended π-conjugation promote the spin-orbital overlaps in N-TMB, leading to Jahn-Teller distortion and the formation of a robust doublet state. Our results not only demonstrate the fabrication of polyradicals based on NHC but also shed light on the effect of NHC and π-conjugation on the electronic structure and spin coupling, which opens up new possibilities for precisely regulating the spin-spin exchange coupling of organic polyradicals.

Secondary metabolites in host pears defense against two fruit borers and cytochrome-P450-mediated counter-defense.

Herbivorous insects have evolved metabolic strategies to survive the challenges posed by plant secondary metabolites (SMs). This study reports an exploration of SMs present in pears, which serve as a defense against invasive Cydia pomonella and native Grapholita molesta and their counter-defense response. The feeding preferences of fruit borers are influenced by the softening of two pear varieties as they ripen. The content of SMs, such as quercetin and rutin, increases due to feeding by fruit borers. Notably, quercetin levels only increase after C. pomonella feeding. The consumption of SMs affects the growth of fruit borer population differently, potentially due to the activation of P450 genes by SMs. These two fruit borers are equipped with specific P450 enzymes that specialize in metabolizing quercetin and rutin, enabling them to adapt to these SMs in their host fruits. These findings provide valuable insights into the coevolution of plants and herbivorous insects.

Silver Surface-Assisted Dehydrobrominative Cross-Coupling between Identical Aryl Bromides.

Cross-coupling reactions represent an indispensable tool in chemical synthesis. An intriguing challenge in this field is to achieve selective cross-coupling between two precursors with similar reactivity or, to the limit, the identical molecules. Here we report an unexpected dehydrobrominative cross-coupling between 1,3,5-tris(2-bromophenyl)benzene molecules on silver surfaces. Using scanning tunneling microscopy, we examine the reaction process at the single-molecular level, quantify the selectivity of the dehydrobrominative cross-coupling, and reveal the modulation of selectivity by substrate lattice-related catalytic activity or molecular assembly effect. Theoretical calculations indicate that the dehydrobrominative cross-coupling proceeds via regioselective C-H bond activation of debrominated TBPB and subsequent highly selective C-C coupling of the radical-based intermediates. The reaction kinetics plays an important role in the selectivity for the cross-coupling. This work not only expands the toolbox for chemical synthesis but also provides important mechanistic insights into the selectivity of coupling reactions on the surface.

Identification of G Protein-Coupled Receptors (GPCRs) Associated with Lambda-Cyhalothrin Detoxification in Cydia pomonella.

While previous studies have reported G protein-coupled receptor (GPCR)-mediated insecticide resistance in various arthropods, the understanding of GPCR-associated resistance mechanisms in Cydia pomonella remains limited. In this study, a total of 95 CpGPCR genes categorized into four families were identified in C. pomonella. Results revealed high expression levels of the majority of the CpGPCRs during the first larval stage and in the head of C. pomonella. Exposure to lambda-cyhalothrin significantly increased the expression of 15 CpGPCRs, including CpGPCR70, which is highly expressed in all larval stages and shows the highest expression in the midgut. RNA interference (RNAi) demonstrated that downregulation of CpGPCR70 leads to reduced expression of key resistance-related genes and a decreased tolerance of larvae to lambda-cyhalothrin. These findings indicate that CpGPCR70 plays a crucial role in regulating the expression of detoxifying genes involved in lambda-cyhalothrin resistance, offering valuable insights for the development of more effective pest control strategies.

Quercetin stimulates an accelerated burst of oviposition-based reproductive strategy in codling moth controlled by juvenile hormone signaling pathway.

The advantageous characteristics of invasive pests, particularly their ability to reproduce and adapt to the environment, have been observed. However, it remains unclear what specific inherent superiority enables fruit pests to successfully invade and dominate in interactions with other species. In this study, we report that Cydia pomonella (Linnaeus), a notorious invasive pest of pome fruits and walnuts globally, employs unique reproductive strategies in response to quercetin, a plant compound in host fruits. By monitoring adult dynamics and fruit infestation rates, we observed a competitive relationship between C. pomonella and the native species Grapholita molesta (Busck). C. pomonella was able to occupy vacant niches to ensure its population growth. We also found that quercetin had different effects on the reproductive capacity and population growth of C. pomonella and G. molesta. While quercetin stimulated the fecundity and population growth of G. molesta, it inhibited C. pomonella. However, C. pomonella was able to rapidly increase its population after exposure to quercetin by adopting an 'accelerated burst' of oviposition strategy, with each individual making a greater reproductive contribution compared to the control. We further demonstrated that the effect of quercetin on oviposition is regulated by the juvenile hormone (JH) signaling pathway in C. pomonella, allowing it to prioritize survival. The enhanced reproductive fitness of G. molesta in response to quercetin is attributed to the regulation of JH titers and key genes such as Met and Kr-h1, which in turn up-regulate reproduction-related genes Vg and VgR. In contrast, C. pomonella is inhibited. These findings shed light on the mechanisms interspecific competition and help to improve our understanding of the global spread of C. pomonella, which can be attributed to its inherent superiority in terms of reproductive strategy.

The study of Yangyinyiqi mixture anti bleomycin-induced pulmonary fibrosis on rats by intervening matrix metalloproteinase-9 and tissue inhibitors of matrix metallopreoteinases-1 / El estudio de la mezcla Yangyinyiqi en fibrosis pulmonar inducida por anti-bleomicina en ratas por intervención en la matriz metaloproteinasa-9 e inhibidores de tejido de matriz metaloproteinasa-1

To investigate effectsof Yangyinyiqi Mixture on pulmonary fibrosis caused by bleomycin. SD ratswere divided randomly into: model group(distilled water,1 mL·0.1 kg-1), dexamethasone acetate group (dexamethasone acetate, the dosage was reduced gradually), low-dose group (Yangyinyiqi Mixture, 11 g·kg-1), moderate-dose group (Yangyinyiqi Mixture, 22 g·kg-1), high-dose group (Yangyinyiqi Mixture, 44 g·kg-1) and control group (distilled water, 1 mL·0.1 kg-1). Yangyinyiqi Mixture and dexamethasone acetate were intragastrically administrated. Lung tissue was collected for histopathological examination. Compared with control group, collagen markedly increased and HYP content significantly increased on 7th day in model group (p<0.01). On 28th day, collagen was diffusely deposited, alveolar was destroyed, and HYP content significantly increased (p<0.01). Compared with model group, bleomycin-induced suffering injury caused MMP-9 expression levels to rapidly increase (7and 14 days, p<0.01). TIMP-1 markedly increased (7and 14 days, p<0.01) and stayed at a high level to28th day. Yangyinyiqi Mixture exerted an effect against pulmonary fibrosis, which could involved prevention of collagen deposition through inhibitingMMP-9 and TIMP-1 expression.

El trabajo investiga los efectos de la mezcla Yangyinyiqi sobre la fibrosis pulmonary causada por bleomicina. Ratas SD se dividieron aleatoriamente en: grupo modelo (agua destilada, 1 mL·0.1 kg-1), grupo acetate de dexametasona (acetate de dexametasona, la dosis se redujo gradualmente), grupo de dosis baja (mezcla Yangyinyiqi, 11 g·kg-1), grupo de dosis moderada (mezcla Yangyinyiqi, 22 g·kg-1), grupo de dosis alta (mezcla Yangyinyiqi, 44 g·kg-1) y grupo control (agua destilada, 1 Ml·0.1 kg-1). La mezcla de Yangyinyiqi y el acetate de dexametasona se administraron por vía intragástrica. Se recolectó tejido pulmonary para examen histopatológico. En comparación con el grupo control, el colágeno aumentó notablemente y el contenido de HYP aumentó significativamente el séptimo día en el grupo modelo (p<0.01). El día 28, el colágeno se depositó difusamente, se produjo destrucción alveolar y el contenido de HYP aumento significativamente (p<0.01). En comparación con el grupo modelo, la lesión inducida por bleomicina causó que los niveles de expression de MMP-9 aumentaron rápidamente (7 y 14 días, p<0.01). TIMP-1 aumentó notablemente (7 y 14 días, p<0.01) y se mantuvo en un nivel alto hasta el día 28. La mezcla Yangyinyiqi ejerció un efecto contra la fibrosis pulmonary, lo que podría implicar la prevención del deposito de colágenio mediante la inhibición de la expression de MMP-9 y TIMP-1.