Electron-donating Groups Research Articles

Chromium(VI) and Nitrate Removal from Groundwater Using Biochar-Assisted Zero Valent Iron Autotrophic Bioreduction: Enhancing Electron Transfer Efficiency and Reducing EPS Accumulation.

Current strategies primarily utilize heterotrophic or mixotrophic bioreduction for the simultaneous removal of Cr(VI) and NO3- from groundwater. However, given the oligotrophic nature of groundwater, autotrophic bioreduction could be more appropriate, though it remains notably underdeveloped. Here, an autotrophic bioreduction technology utilizing biochar (BC)-assisted zero valent iron (ZVI) is proposed. The pyrolysis temperature of BC was optimized to enhance electron transfer efficiency and reduce extracellular polymeric substances (EPS) accumulation. BC500, with the superior electron transfer capabilities, was the most effective. After an 11-week period, the ZVI+BC500 biotic column still achieved 100% removal efficiency for Cr(VI) and 93.37±0.33% for NO3-, with initial concentrations of 26 mg/L and 50 mg/L, respectively. Its performance significantly surpasses that of ZVI alone, effectively reducing the interference of Cr(VI) on denitrification. The presence of quinone and phenolic compounds in BC500, serving as electron-accepting and electron-donating groups, improves the efficiency of electron transfer between ZVI and microbes. Metagenomic analysis showed an increase in the growth of autotrophic bacteria such as Hydrogenophaga spp. and Rhodanobacter denitrificans, and heterotrophic bacteria including Arenimonas daejeonensis and Chryseobacterium shandongense. The promotion facilitates the expression of genes associated with Cr(VI) reduction (chrR, nemA) and denitrification (narG, nirS). BC500 also enhanced EPS production, which facilitates the adsorption and reduction of Cr(VI), mitigating its inhibitory effects on denitrification. Notably, in the ZVI+BC500 biotic column, the accumulated EPS primarily consists of loosely bound EPS rather than tightly bound EPS, potentially reducing the risk of pore clogging during in-situ groundwater treatment.

Differentiated Intra-Ligand Charge Transfer Boosting Multicolor Responsive MOF Heterostructures as Robust Anti-Counterfeiting Labels.

Metal-organic framework (MOF) heterostructures with hybrid architectures and abundant functional sites possess great potential applications in advanced information security, yet still suffer from the harsh stimuli mechanisms with restrained emission control. Herein, the differentiated design strategy on intra-ligand charge transfer is first reported to realize smart-responsive multicolor MOF heterostructures as robust anticounterfeiting labels. Designed similar MOF blocks with the differentiated intra-ligand charge transfer are integrated via time-dependent epitaxial growth to form multicolor MOF heterostructures. Different numbers of electron-donating groups in MOF blocks offer distinct space regulation on the torsion of charge transfer ligands, which trigger the diverse responsive emissions under the same mild stimuli, thus generating multiple tunable color patterns in heterostructures. These spatial-resolved MOF heterostructures with stable multicolor responsive modes permit the encoding of fingerprint information, which further functions as robust anti-counterfeiting labels with high-security convert states. These results offer a promising route for the function-oriented exploitation of smart-responsive MOF heterosystems for advanced information anticounterfeiting.

Development of Glycosylation Protocols Using Glycosyl N-Phenylethynyl Pyrrole-2-carboxylates as Donors.

We herein introduce glycosyl N-phenylethynyl pyrrole-2-carboxylates (PEPCs) as novel and highly efficient glycosyl donors. The unique inclusion of the pyrrole group, serving as both an electron-donating group and an ortho-tethering scaffold, imparts exceptional shelf stability while retaining reactivity for glycosylation reactions. PEPC donors exhibit broad utility for both O- and N-glycosylation across a variety of substrates. Additionally, their versatility and efficiency were further demonstrated in a one-pot saccharide synthesis, showcasing their potential for diverse synthetic applications.

Optimization across-the-Board: Centro-Arylated Push-Pull Tetraene Chromophores and Guest-Host Polymers for Electro-Optics.

The research and development of push-pull tetraene chromophores (PPT-phores) have contributed greatly to the field of organic electro-optic (EO) materials and devices since the inauguration of CLD-1 in 2001. This study is thus a systematic contribution to synthesize and characterize a series of centro-arylated PPT-phores based on strong electron-donating tetrahydroquinolinyl groups and variable strong electron-accepting tricyanofuran derivatives. In particular, we report the crystallographic data to show various packing modes of these PPT-phores with detailed information about bond length alternation and intermolecular interactions, the optical absorption edges of guest-host polymers by the Tauc model, and the anisotropy and dispersion of Pockels tensors for the poled polymers by attenuated total reflection spectroscopy. Such analyses have not been addressed to any significant extent previously and are fundamentally important to the future development of PPT-phore-based EO materials and devices. The poled films of several centro-arylated PPT-phores in polycarbonates exhibited large EO activities, excellent thermal stability, and tunable optical transparency at the telecom O- and C-band. The study demonstrates the effectiveness of π-bridge centro-arylation enabled by molecular shape modification and rigidity enhancement, over the relatively flexible and labile thioether or alkoxy groups, in rational design of hyperpolarizable PPT-phores for high-performance EO polymers.

Plasma Tailoring of NH2-MIL-53 with Enhanced Fluorescence Emission for Simultaneous Detection of Multiple Heavy Metals in Water.

Indium, copper, and mercury are important raw materials in the electronics industry and often coexist in factory wastewater. Therefore, the development of a highly sensitive and selective method for the simultaneous detection of these heavy metal ions is of great significance for water quality monitoring and environmental protection. Herein, we report a NH2-MIL-53 fluorescent probe for the simultaneous detection of trace In3+, Cu2+, and Hg2+ in water. After a low-temperature NH3 plasma tailoring treatment for grafting electron-donor amine groups, the obtained NH2-MIL-53-M exhibited enhanced fluorescence emission intensity (∼6 times) coupled with selective adsorption of In3+, Cu2+, and Hg2+. This quenched the NH2-MIL-53-M fluorescence and allowed to significantly increase the selectivity and sensitivity for detection of In3+, Cu2+, and Hg2+. The fluorescence quenching constant (Ksv) values were 2.23 × 105, 1.00 × 105, and 2.74 × 104 M-1, while the limit of detection (LODs) values were 0.06, 0.14, and 0.53 μM, for In3+, Cu2+, and Hg2+, respectively. The concentrations of In3+, Cu2+, and Hg2+ in real environmental samples could be determined by addition of appropriate masking agents, and the recoveries were within the range of 94-110%. This study not only supplied a strategy for constructing a highly sensitive and selective fluorescent probe but also established a platform for simultaneous detection of multiple heavy metal ions in water.

Chemoenzymatic Cyclization by Vanadium Chloroperoxidase for Synthesis of 4-Hydroxyisochroman-1-ones.

4-Hydroxyisochroman-1-ones belong to the class of the secondary metabolite 3,4-dihydroisocoumarins. They exhibit a wide range of biological activities. These compounds can be synthesized through halocyclization using hypervalent iodine species or N-bromosuccinimide, followed by hydrolysis. Nonetheless, the reactions required specific conditions and generated toxic byproducts. In this study, Curvularia inaequalis vanadium chloroperoxidase (CiVCPO) catalyzed the chemoenzymatic cyclization of 2-vinylbenzoic acids with different electron-donating groups (1a-1e) to produce good yields of 4-hydroxyisochroman-1-ones (3a-3e) by adding KBr and H2O2 in citrate buffer (pH 5). The reaction mixture contained 30% DMSO to improve substrate solubility without enzyme activity loss. The condition is more environmentally friendly than chemical methods. Therefore, it offers an alternative approach for synthesizing 4-hydroxyisochroman-1-ones.

The Impact of π-Bridge Moiety on the Optoelectronic Properties and Photochemical Stabilities of Benzodithiophene-Based Conjugated Polymers

The stability of conjugated polymers (CPs) under exposure to light and air determines their sustainability for commercial use and their possible usage in diverse areas. The main goal of this study is to examine how changes in the π-bridge of polymers affect their electrochemical and optoelectronic properties. Furthermore, it seeks to evaluate the impact of these alterations on the photochemical durability of the polymers. Three D-π-A types of CPs were synthesized via Stille coupling. All polymers consist of the same acceptor and donor units, which were benzooxadiazole (BOz) and benzo[1,2-b:4,5-b']dithiophene (BDT), respectively, but they had different π-bridge such as thiophene (T), selenophene (Se), and thiazole (Tz).This study used a variety of spectroscopic tools such as UV-Vis, FTIR, and XPS, to investigate how photooxidation occurs. DFT calculations were used to further support the experimental results. Within a mere 30-minute timeframe, the primary absorption peak of the polymer films experienced a blue shift and a significant reduction in intensity due to being exposed to both light and air simultaneously. Despite the presence of the same electron-withdrawing group, BOz, and electron-donating group, BDT, in all polymers, the photochemical stability varies with π-bridges. T- and Se-containing conjugated polymer films (P1-T, P2-Se) exhibited a significant decrease in the intensity of their peak absorption, whereas the peak intensity and characteristics of their thiazole counterpart (P3-Tz) only showed a slight alteration after being exposed to light and air for up to 7 hours. The superior photostability of the P3-Tz polymer film can be attributed to a significantly higher HOMO level and higher band gap in comparison to P1-T and P2-Se.Comprehending the photochemical stability of these polymers is crucial for progressing their commercial uses, such as organic photovoltaics, OLEDs, and sensors. This study highlights the significance of choosing suitable π-bridges to improve the longevity and effectiveness of CPs, thus satisfying market requirements and broadening their possible applications.

Electronic effect tuned ion-dipole interactions for low-temperature electrolyte design of LiFePO4-based lithium-ion batteries

Poor low-temperature performance is one of the major challenges hindering the widespread use of lithium-ion batteries. Modulation of Li+ solvation structure to facilitate desolvation process is an important strategy in electrolyte engineering under low temperature. Herein, different electronic effect groups including electron-withdrawing groups (CH2Cl) and electron-donating groups (CH3), are introduced in the weakly solvated solvent tetrahydrofuran (THF), respectively, to compare their effects on the ion-dipole interaction in the electrolyte and thus the regulation of Li+ solvation structure. Theoretical calculations combined with characterization demonstrates that the introduction of electron-withdrawing groups CH2Cl in the solvent can reduce the electron cloud density of oxygen in the THF solvent molecule, weaken the binding energy between Li+ and the solvent, and lead to more anions participating in solvation shell of Li+ and coordinating with Li+, thus accelerating the desolvation kinetics of Li+. This electrolyte-design strategy based on electronic effect tuned ion-dipole interactions has notably increased the cycling stability of the LiFePO4||Li half-cell at −20 °C, that is, it not only increases the capacity by about 10 mAh g−1 at the rate of 0.2 C, but also maintains the capacity retention rate at 97.4 % after 100 cycles. This study reveals an important electrolyte design strategy at the molecular level.

Modifying functional groups of straw-based hydrogel provide soil N2O mitigation potential by complete denitrification

Farmed soil is considered to contribute more than 60% anthropogenic N2O emission which plays critical role in global warming potential. Straw-based hydrogels with abundant functional groups are commonly used in environmental and agronomic applications primarily as adsorbents. Those functional groups could mediate electron transfer in the process of adsorbates and might also regulate N2O emission. However, it was still unclear whether and how these functional groups affect the process. To address this knowledge gap, we employed spectral analysis and a robotized incubation system to determine mechanisms of different functional groups in influencing soil N2O. The results indicated that the straw-based hydrogel was capable of significantly reducing the emission of N2O in denitrification, and the electrochemical properties of the hydrogel had promoting effect of the microbial genetic potential for N2O reduction. Specifically, carboxymethyl (R-COO) and primary amine groups (R-NH2) promoted complete denitrification through electron supply. Furthermore, R-NH2 had a significant negative correlation with N2O emissions. To further verify the role of specific structures and functional groups in denitrification, we conducted an experiment using pure lignin as a template. This experiment resulted in an increase in R-NH2 content to 13.2% and a decrease in N2O emissions by 49.1% compared with straw hydrogel. These results prove the feasibility of straw-based hydrogel as a redox system to accelerate complete denitrification, and the electron-donating functional groups were significantly related to the reduction rate of N2O. Finally, based on these mechanisms, functional group targeted grafting technology was proposed to improve its ability to mitigate N2O emission reduction.

Theoretical exploration on the combined effect of isoelectron B-N bonds and B-N resonance skeleton on the thermally activated delayed fluorescence property

The multiple resonance thermally activated delayed fluorescence (MR-TADF) materials has become a hot spot in recent years depending on their potential in achieving an internal quantum efficiency of 100%. The combined effect of para B-N resonance skeleton and isoelectron B-N bonds on the TADF property was investigated in details by employing density functional theory/time-dependent density functional theory (DFT/TDDFT) in this work based on four polycyclic aromatic molecules. The results show that isoelectron B-N bonds are favourable to the enhancement of spin orbital coupling (SOC) constants between the first singlet state (S1) and the first triplet state (T1), while para B-N resonance skeleton is more conducive to reducing the energy gap between S1 and T1 (ΔEST) through realizing short-range charge transfer character and keeping electron and hole localized at different atoms. Accordingly the combination of isoelectron B-N bonds and para B-N resonance skeleton in m[B-N]N1 and m[B-N]N2 could realize faster intersystem crossing (ISC) and reverse intersystem crossing (RISC) processes through larger SOC and lower ΔEST compared with BCz-BN and NBN-2 which only contain para B-N resonance skeleton and isoelectron B-N bonds, respectively. At the same time, the para B-N resonance skeleton help to stabilize the structure of polycyclic aromatic hydrocarbons and localize the vibration in low frequency region during emission from S1 to ground state. Thus larger nonradiative rates induced by the rotation of carbazole and tert-butyl carbazole in low frequency region in m[B-N]N1 and m[B-N]N2 could be easily reduced by replacing them by small functional group such as electron-donating (-CH3) and electron-withdrawing (-CN) groups. Therefore, we can obtain high TADF efficiency through combining para B-N resonance skeleton and isoelectron B-N bonds and suppressing low-frequency vibrations as in our designed molecules m[B-N]CH3 and m[B-N]CN.

Mechanism of unactivated peroxymonosulfate-induced degradation of amino-G acid: Kinetics and transformation pathway

Amino-G acid (7-amino-1,3-naphthalenedisulfonic acid), a pollutant produced during textile preparation and in dyeing industries, is discarded in wastewater and causes ecological problems. In this study, amino-G acid (50.0 μM) could be completely removed by unactivated peroxymonosulfate (PMS) (1.0 mM) within 240 min, and the reaction kinetics exhibited strong pH dependence. A species-specific parallel reaction describes this pH dependence well, and the species-specific reaction rate constants of [amino-G acid]2− and [amino-G acid]− with HSO5− were calculated to be 0.0826 ± 0.0019 and 000122 ± 0.0027 M−1 s−1. The reactivity of the six naphthalene sulfonic acids and unactivated PMS varied according to the structure, and the amino group in naphthalene sulfonic acid, a typical electron-donating group, was more vulnerable to attack by unactivated PMS, which was further confirmed by the density functional theory results. The high-performance liquid chromatography coupled to mass spectrometry (HPLC-MS) spectral analysis results indicated that naphthalene sulfonic acid was first oxidized to hydroxylamine products and then further oxidized to nitroso compounds, which exhibited more ecological toxicity. However, as the reaction processing, the toxicity of the product gradually decreased. Our results provide new insights into the in-situ oxidation of unactivated PMS.

Boosting photocatalytic H2O2 production by incorporating extra electron-donor group over resorcinol-formaldehyde resin

Boosting photocatalytic H2O2 production by incorporating extra electron-donor group over resorcinol-formaldehyde resin

Functional Hexafluoroisopropyl Group Used in the Construction of Biologically Important Pyrimidine Derivatives.

A series of versatile 4-((1,1,1,3,3,3-hexafluoropropan-2-yl)oxy)pyridine intermediates have been developed to efficiently produce biaryls, amines, ethers, and thioethers. These hydrolysis-stable ether intermediates exhibit reactivity toward electron-donating groups and nucleophiles in cross-coupling and nucleophilic substitution reactions while surpassing the stability of corresponding aryl halides. In comparison to conventional coupling methods, this protocol offers an alternative pathway for accessing natural product and drug-like compounds without the need for metal catalysts. With assistance of this approach, we successfully obtained a potent P-glycoprotein inhibitor 4k (YS-370), a potent epidermal growth factor receptor inhibitor 4l (YS-363), and a promising lysine-specific demethylase 1 inhibitor 5g.

The role of Lewis acidity in bis(β-diketonate)zirconium(IV) complexes as catalysts for the ring-opening polymerization of δ-valerolactone

Poly(δ-valerolactone) (PVL) is a polymer that has garnered significant researcher interest due to its intriguing features and prospective uses across numerous domains, particularly in medicine. This work aimed to assess the influence of the Lewis acidity of the bis(β-diketonate)Zr catalyst complex on the ring-opening polymerization of δ-valerolactone. The ligand in the compound contains an electron-donating group, specifically the methyl group (2a). Furthermore, electron-withdrawing groups employed include phenyl (2b–2c) and trifluoromethyl groups (2d). Characterization data indicate that PVL has been successfully synthesized with a bis(β-diketonate)Zr complex catalyst. The hierarchy of Lewis acid strength for the bis(β-diketonate)Zr complex is 2c > 2b > 2d ≫ 2a. The sequence of PVL DP from highest to lowest is 2b, 2c, 2d and 2a. Nonetheless, the elevated Lewis acidity of complex 2c does not provide PVL with the greatest degree of polymerization. The steric barrier of complex 2c, which contains two phenyl groups, is larger than that in complex 2b. Consequently, the coordination process of the nucleophilic monomer with the electrophilic zirconium central atom becomes increasingly difficult.

Structural and electronic tuning of single-benzene fluorophores with simple methylations

Recent advancements in the development of low molecular-weight fluorophores have led to the study of a single-benzene fluorophore (SBF) containing both electron-withdrawing and electron-donating groups within an aromatic ring, resulting in unique photophysical properties. In this study, we explored the modulation of emissions by adjusting the electron-donating properties via the simple methylation of the 2,5-diamino or 2,5-dihydroxy terephthalate structure. Introducing additional functional groups under both symmetrical and unsymmetrical conditions demonstrated changes in the photophysical properties, which was not only owing to the structural variations in the location and number of methyl groups but also due to alterations in the electron-donating properties. The observed effects appeared to be owing to the interactions between the amine and ester groups, as confirmed via single-crystal X-ray diffraction. Finally, hydrolysis of the ester to the corresponding carboxylic acid resulted in various emission wavelengths at different pH values via protonation and deprotonation. This study provides valuable insights for predicting the structural and electronic effects of additional functional groups in SBF.

Highly efficient synthesis of di-substituted allenes via copper-catalyzed SN2′- substitution reaction of organotitanium reagents with propargyl bromides

A simple and mild catalytic SN2′-type displacement of propargyl halides with organotitanium reagents is reported. The SN2′-type displacement of propargyl bromides with organotitanium reagents mediated by CuI (2 mol%)/MePPh2(4 mol%) in dichloro methane afforded multi-substituted allenes in good yields (up to 95 %) at 40 °C for 5 h. The aryls bearing electron-donating or electron-withdrawing groups in aryltitanium reagents gave multi-substituted allenes in good yields. In addition, the di-substituted allenes bearing a naphthyl group was obtained in 54–99 % selectivities with isolated yields of 43–83 %. The process was simple and easily performed, and it provides an efficient method for the synthesis of di-substituted allene derivatives. On the basis of the experimental results, a possible catalytic cycle has been proposed.

PPh3 promoted stereospecific synthesis of ethyl α-chloroacrylates from ethyl trichloroacetate and arylaldehydes

A coupling reaction between arylaldehydes and ethyl trichloroacetate is facilitated by PPh3 under mild conditions to stereospecifically produce (Z)-ethyl α-chloroacrylates. This stereospecific coupling reaction only occurs when the arylaldehyde derivative has an electron-withdrawing substituent. On the other hand, when an electron-donating group is present in the aromatic ring, the aryldichloromethyl derivative is formed as the only product, even at low temperature. The stereospecificity in the coupling reaction was established based on the coupling constants 2JCH and 3JCH in the 13C NMR and crystal-X-ray analysis. From this data we propose that the formation of these compounds occurs through two intermediates initially formed by the reaction between the PPh3 and ethyl trichloroacetate.

Synthesis and Structure of Novel Hybrid Compounds Containing Phthalazin-1(2H)-imine and 4,5-Dihydro-1H-imidazole Cores and Their Sulfonyl Derivatives with Potential Biological Activities.

A novel hybrid compound-2-(4,5-dihydro-1H-imidazol-2-yl)phthalazin-1(2H)-imine (5) was synthesized and converted into di-substituted sulfonamide derivatives 6a-o and phthalazine ring opening products-hydrazonomethylbenzonitriles 7a-m. The newly prepared compounds were characterized using elemental analyses, IR and NMR spectroscopy, as well as mass spectrometry. Single crystal X-ray diffraction data were collected for the representative compounds 5, 6c, 6e, 7g, and 7k. The antiproliferative activity of compound 5, sulfonyl derivatives 6a-o and benzonitriles 7a-m was evaluated on approximately sixty cell lines within nine tumor-type subpanels, including leukemia, lung, colon, CNS, melanoma, ovarian, renal, prostate, and breast. None of the tested compounds showed any activity against the cancer cell lines used. The antioxidant properties of all compounds were assessed using the DPPH, ABTS, and FRAP radical scavenging methods, as well as the β-carotene bleaching test. Antiradical tests revealed that among the investigated compounds, a moderate ABTS antiradical effect was observed for sulfonamide 6j (IC50 = 52.77 µg/mL). Benzonitrile 7i bearing two chlorine atoms on a phenyl ring system showed activity in a β-carotene bleaching test (IC50 = 86.21 µg/mL). Finally, the interaction AGE/RAGE in the presence of the selected phthalazinimines 6a, 6b, 6g, 6m, and hydrazonomethylbenzonitriles 7a, 7c-g, and 7i-k was determined by ELISA assay. A moderate inhibitory potency toward RAGE was found for hydrazonomethylbenzonitriles-7d with an electron-donating methoxy group (R = 3-CH3O-C6H4) and 7f, 7k with an electron-withdrawing substituent (7f, R = 2-Cl-C6H4; 7k, R = 4-NO2-C6H4).

Palladium-Catalyzed Ortho Alkoxylation of Oxazoline Derivatives: An Avenue to Reach Meta-Substituted Electron-Rich Arenes Exploiting Oxazoline as a Removeable Directing Group.

An efficient and highly regioselective palladium-catalyzed oxazoline-directed alkoxylation is reported. The reaction proceeds under air and mild temperatures (60 °C). A series of alcohols can be used as alkoxylating agents and concomitantly act as reaction solvents, whereas primary and secondary alcohols are tolerated. Furthermore, fluorinated alcohols can be applied as well, introducing pharmaceutically relevant fluorine-containing groups. 1,3-Dialkoxylated products can be further subjected to hydrolysis transforming the oxazoline-directing group to a carboxylic acid, which can be removed by decarboxylation if desired. This approach demonstrates the capability to reverse the conventional site selectivity of electrophilic aromatic substitution reactions, since it allows the synthesis of arenes with two electron-donating groups in a 1,3-relationship.

Novel "Phenyl-Pyrazoline-Oxadiazole" Ternary Substructure Derivatives: Synthesis, Insecticidal Activities, and Structure-Activity Relationship Study.

In recent years, isoxazole insecticides or parasiticides targeting the γ-aminobutyric acid receptor, such as fluralaner or fluxametamide, featured a novel chemical structure and exhibited potent insecticidal activity with no-cross resistance. Thus, many research institutes have tried to modify the structures of these agents to find a new insecticide. Previously, the majority of researchers stuck to the "phenyl-isoxazole-phenyl" structure, making modifications only to other components. In this study, the "phenyl-isoxazole-phenyl" ternary motif was modified for the first time based on bioisosterism theory. A series of new derivatives carrying pyrazoline and 1,3,4-oxadiazole moieties were designed and synthesized to investigate their insecticidal activities against the diamondback moth (Plutella xylostella) and fall armyworm (Spodoptera frugiperda). Preliminary bioassay data showed that some of the target compounds exhibited good insecticidal activities against P. xylostella and S. frugiperda. Especially, compound A21 showed insecticidal activity against P. xylostella (LC50 = 1.2 μg/mL) better than commercial insecticide ethiprole (LC50 = 2.9 μg/mL) but worse than parasiticide fluralaner (LC50 = 0.5 μg/mL). Similarly, compound A21 exhibited insecticidal activity to S. frugiperda (LC50 = 13.2 μg/mL) better than commercial insecticide fipronil (LC50 = 78.8 μg/mL) but worse than fluralaner (LC50 = 0.7 μg/mL). Compound A21 could serve as a potential lead compound to control P. xylostella and S. frugiperda. The three-dimensional quantitative structure-activity relationship model revealed that the further introduction of an electron-donating group in the 2- or 3-site may increase the insecticidal activity of A21. Molecular dynamics simulations showed that the hydrogen bond of A21 and receptor was important for the binding receptor. This study has identified a new substructure called "phenyl-pyrroline-oxadiazole" instead of the previously known "phenyl-isoxazole-phenyl" substructure, offering a useful guide for the design of novel insecticide molecules.