Search Results (644)

Zinc and iron are essential micronutrients in crop nutrition, and polymer-based nanogels have emerged as promising carriers to modulate their availability in sustainable agricultural systems. Here, a polymeric model receptor was designed to investigate how the nature and position of electron-donating (–NH₂) and electron-withdrawing (–NO₂) substituents control the recognition of Zn²⁺ and Fe²⁺ cations. Using a combination of density functional theory calculations, energy decomposition analysis with natural orbitals for chemical valence (EDA–NOCV), electrostatic potential (ESP) mapping, and quantum theory of atoms in molecules (QTAIM) method, the receptor–cation interactions are dissected into electrostatic, Pauli repulsion, orbital, and dispersion contributions. The results show that complex stability is governed mainly by orbital and electrostatic terms, with Fe²⁺ forming the most stable complex (−393.57 kcal mol⁻¹) with regard to a Zn²⁺ similar complex (−288.80 kcal mol⁻¹). Zn²⁺ complexes exhibit a broad tunability with substituent pattern. Electron-donating groups systematically strengthen both electrostatic and orbital components, whereas nitro substituents display a pronounced positional effect, ranging from strong destabilization to significant stabilization of Zn²⁺ binding. These findings establish molecular-level guidelines for engineering polymeric nanogels with tunable affinity and selectivity toward micronutrient cations in agricultural applications. Full article

Two series of N-hydroxyalkyl-1,8-naphthalimide derivatives were synthesized to investigate the influence of structural variables on their electrochemical and photophysical properties. The first series includes compounds containing N-hydroxyalkyl substituents of various chain lengths and branches. The second series includes derivatives functionalized in the naphthalene core with electron-donating or electron-withdrawing groups. Cyclic voltammetry, UV–Vis spectroscopy and fluorescence measurements were supported by theoretical DFT calculations. Branched hydroxyalkyl chains enhanced photoluminescence quantum yields by up to 19%, compared to less than 4% for linear chains. Functionalization of the naphthalene core at the C4 position strongly affected optical band gaps, electrochemical properties and photoluminescence quantum yields. DFT calculations revealed significant changes in the energies of the frontier orbits: the HOMO energy varied from −6.95 eV to −5.51 eV, while the LUMO energy varied from −3.24 eV to −1.94 eV. Preliminary tests have demonstrated the suitability of the selected derivatives as cathode materials in lithium-ion batteries, achieving an initial capacity of 47 mAh/g. Full article

Donor–acceptor (D-A)-type conjugated porous polymers (CPPs) have emerged as highly competitive photocatalysts for aerobic oxidation reactions. Herein, we rationally design and synthesize a series of D-A structured photocatalysts by employing dibenzothiophene-S, S-dioxide (BTDO) as the acceptor unit, and 4,8-bis(thiophen-2-yl) benzo [1,2-b:4,5-b’] dithiophene (DBD) and pyrene (Py) as the donor units. The effects of acceptor content on the optoelectronic and photocatalytic properties are systematically investigated. With the gradual increase in BTDO proportion and the decrease in pyrene content, the photocatalysts exhibit gradually narrowed band gaps, significantly promoted charge separation efficiency, and broadened visible light absorption range. Among the five as-prepared photocatalysts, DBD-T displays superior catalytic performance toward blue light-driven aerobic oxidation. Under mild conditions, benzyl sulfide and benzyl amine are selectively converted into benzyl sulfoxide and benzyl imine with a high conversion efficiency up to 96%. Moreover, DBD-T shows good universality toward a wide range of substrates, together with excellent recyclability and long-term stability. This work demonstrates that enhancing the electron-withdrawing capability of the acceptor unit represents a feasible and effective strategy to boost the photocatalytic performance of D-A-type conjugated polymers. Full article

Phenazine derivatives are promising metal-free chromophores with strong redox and photophysical properties, yet their use in photocatalytic hydrogenation remains limited. Here, we report a homogeneous phenazine-based system for the visible-light-driven hydrogenation of nitroarenes under mild conditions. Using nitrobenzene as a model substrate and triethanolamine as a sacrificial hydrogen source, the photocatalyst achieved aniline yields of up to 81% after 12 h of irradiation at 390 nm. Systematic variation in reaction parameters revealed that catalyst structure, solvent, and light wavelength strongly influence performance. Kinetic analysis indicated that prolonged irradiation reduces overall yield due to the reconversion of reactive intermediates. The system exhibited higher efficiency toward nitroarenes bearing electron-withdrawing groups, while aliphatic nitro compounds underwent only partial reduction. Mechanistic studies using UV–Vis, fluorescence, and EPR spectroscopy confirmed the formation of persistent radical species and supported a stepwise electron and proton transfer mechanism. This work showcases the potential of phenazine-based photocatalysts as metal-free platforms for nitroarene reduction under visible light. Full article

A modular synthetic route has been developed to prepare a new series of cationic ruthenium(II) complexes with electron-withdrawing 1,2-diacylcyclopentadienyl ligands. The 2-acyl-6-hydroxyfulvenes were synthesized from cyclopentadienide and acyl chlorides and converted to Tl(I) cyclopentadienyl salts using Tl₂SO₄/KOH. Transmetalation with [Ru(η⁶-p-cymene)(μ-Cl)Cl]₂ followed by PF₆⁻ metathesis gives the complexes [Ru{η⁵-1,2-C₅H₃(CO–R)₂}(η⁶-p-cymene)][PF₆] (R = t-Bu, p-Tol, p-ClC₆H₄, p-IC₆H₄) in moderate to high yields. The new compounds were characterized by NMR and IR spectroscopy; mass spectrometry and elemental analysis were performed where applicable. X-ray analysis of one of the complexes confirms that electron-deficient Cp ligands retain η⁵-coordination and structural planarity within Ru(II)–arene sandwich architectures, highlighting their potential utility in electronically tunable organometallic frameworks. Full article

Background/Objectives: Adenine derivatives are promising anticancer scaffolds, but their cellular mechanisms remain unclear. This study aimed to synthesize adenine–hydrazone hybrids and evaluate their cytotoxic effects in human lung adenocarcinoma (A549) cells. Methods: A series of adenine–hydrazone compounds (3a–r) was synthesized and tested for cytotoxicity in A549 and MRC-5 cells. Selected compounds were further analyzed for LDH release, oxidative stress markers, ROS production, mitochondrial membrane potential, cell-cycle distribution, apoptosis, and in silico docking against VEGFR2, ALK5, and EGFR. Results: Compounds with electron-withdrawing or donor–acceptor substituents showed the highest cytotoxicity, while halogenated and methoxy analogs were moderately active. Among the synthesized derivatives, 4F-substituted derivatives (3c) showed more activity than 2F- and 3F-substituted ones (3a and 3b). 4F- and 3Br-substituted derivatives (3f) showed more activity than only 4F-substituted ones (3c). 4-Nitro-substituted derivative (3i) showed more activity than 4F- (3c), 4Cl- (3d) and 4OMe- (3h) derivatives. Trimethoxy-substituted derivative (3l) showed more activity than di- and mono-substituted methoxy derivatives (3g, 3h, 3j and 3k). Among the salicyl aldehydederivatives (3m–r), 4-N(et)₂-substituted derivative (3r) showed more activity than non-substituted (3m), 5Br-(3n), 5Cl-(3o), 5Me (3p) and 3OCH₃ (3q) derivatives. Treatment induced oxidative stress, mitochondrial depolarization, Sub-G1 cell-cycle accumulation, and apoptosis. Docking studies indicated strong binding to VEGFR2 and ALK5, suggesting dual inhibition as a potential mechanism. Conclusions: Adenine–hydrazone derivatives exert substituent-dependent anticancer effects by inducing redox imbalance-associated mitochondrial dysfunction and regulated cell death. These results highlight their potential as lead structures for lung cancer therapy. Full article

The compound eye of the family Psyllidae (Hemiptera: Sternorrhyncha) remains one of the least studied among hemipteran insects. Among the approximately 4000 psyllid species worldwide, the pear psyllid Cacopsylla chinensis (Yang et Li) is a major pest of pear trees in China. The ultrastructure of the compound eye of adult C. chinensis was investigated using a transmission electron microscope (n = 12 adult). The eyes are of the apposition type, lacking a clear zone. Each ommatidium features a laminated corneal lens (about 16.9 ± 1.7 μm in diameter and 7.6 ± 1.7 μm in thickness), a eucone crystalline cone, a centrally fused rhabdom formed by eight retinula cells (R1–R8), and both primary and secondary pigment cells. The 57.0 ± 3.6 μm long rhabdom exhibits a two-tiered structure: a distal region comprising R1-R7 and a proximal region composed of R1-R6 and R8, with R7 withdrawing. Throughout this structure, the rhabdomeres of R1-R6 contribute continuously along the entire length, while R7 and R8 are restricted to the distal and proximal regions, respectively. The microvilli of the rhabdom are arranged in two orthogonal directions. Based on the similarity between the compound eye of C. chinensis and those of other diurnal hemipterans, the evolution and function of eyes are briefly discussed. Full article

Proliferating cell nuclear antigen (PCNA) is a critical regulator of DNA replication and repair, and its cancer-associated isoforms represent promising therapeutic targets. The small molecule AOH1996 has been previously reported as a PCNA inhibitor with potent antiproliferative activity. Here, a series of novel AOH1996-based structural analogs were synthesized using structure–activity relationship (SAR) and scaffold-hopping strategies, including 1,2,3-triazole, glycine, and amide derivatives with diverse aromatic and polar substituents. The antiproliferative activity of these compounds was evaluated in MCF-7 (breast cancer) and U87 (glioblastoma) cell lines using the MTT assay. The parent compound AOH1996 exhibited the strongest cytotoxicity, reducing cell viability below 30% at 10 μM. Among the analogs, compounds 1f, 2b, 3b, 3c, and 3d demonstrated significant activity, reducing MCF-7 viability by 60–70% and U87 viability to 30–40% at 10 μM. SAR analysis revealed that electron-withdrawing or moderately lipophilic substituents on the amide side chain and aromatic extensions on the triazole ring enhanced potency, while bulky or strongly electron-donating groups diminished activity. ADMET predictions indicated that most derivatives possessed favorable drug likeness and absorption potential, but high plasma protein binding, short predicted half-lives, and potential cardiotoxicity represent limitations that will require further optimization. Several active compounds were predicted to inhibit P-glycoprotein, suggesting their potential to overcome multidrug resistance. Overall, compounds 2b and 3b showed relatively favorable predicted profiles and can serve as useful lead scaffolds for further optimization and experimental validation. Full article

Phytocompounds undoubtedly are structurally diverse and play a crucial role in the development of novel therapeutic agents. 2-Hydroxy-4-methoxybenzaldehyde (HMB), from Hemidesmus indicus, is a potent antibacterial agent. Yet its pharmacophore has not been mechanistically defined. Here, we deconstructed HMB through a panel of structural derivatives to delineate the core structural determinants driving activity against foodborne pathogens. Structure–activity analysis revealed that the core benzaldehyde structure, rather than HMB itself, is the minimal active pharmacophore, with specific functional substitutions modulating antibacterial activity and membrane affinity. Integrating an experimental membrane assay with molecular dynamics simulations provided the first atomistic insight into how these derivatives interact with bacterial membrane lipids, demonstrating that substituent-driven modulation of hydrogen bonding dictates antibacterial potency. Specifically, electron-withdrawing groups enhanced membrane penetration and depolarization, particularly in Gram-positive pathogens. Time–kill kinetics and functional assays confirmed bactericidal action via membrane disruption rather than DNA interaction. Crucially, the active derivatives exhibited negligible cytotoxicity toward mammalian Vero cells, confirming their potential as selective and safe natural preservatives. This work provides a mechanistic blueprint for designing benzaldehyde-based antibacterials to combat antimicrobial resistance. Full article

Developing molecular electrocatalysts with controllable and predictable properties remains a central challenge in hydrogen evolution reaction (HER) catalysis. Herein, four Sb(III) corrole complexes (1–4) bearing zero to three p-cyano-substituted meso-phenyl groups (-CN Ph) were synthesized to investigate the effect of electron-withdrawing substituents on their catalytic HER performance, in which complexes 2–4 are newly reported. All prepared complexes were well characterized via UV–vis, NMR, HRMS, and XPS. SEM–EDS and UV–vis analyses indicated their uniform dispersion and excellent stability under organic and neutral aqueous solvent electrolysis conditions. When using TsOH as the proton source in DMF, complex 4 exhibited the highest activity with a TOF of 42.19 s⁻¹ at an overpotential of 895 mV. In mixed aqueous–organic media, the Faradaic efficiency of complex 4 reached 85.5%. The HER activity increases with the increasing number of cyano groups, and this observation has been rationalized via DFT calculations, which indicates a ligand-centered reduction and supports a possible ECEC pathway for the HER. These results highlight that cyano functionalization can modulate the electronic properties of Sb(III) corroles, thereby enhancing HER performance. This is helpful for designing efficient Sb(III) corrole-based HER catalysts. Full article

Despite the promising exploration potential of the tight bioclastic limestone in the Carboniferous Shiqiantan Formation (Shiqiantan Sag, Junggar Basin), its reservoir characteristics remain poorly constrained. In particular, the macro and microscopic features and the key factors controlling reservoir development are still not well understood. We combined core observation, cast thin-section analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD), high-pressure mercury intrusion, nitrogen adsorption, and nuclear magnetic resonance (NMR) to systematically characterize the Carboniferous bioclastic limestone reservoirs and identify the factors controlling their development in the Shiqiantan Sag. This study develops a multi-scale quantitative framework that integrates mercury intrusion–withdrawal behavior, nitrogen adsorption, and NMR T₂ spectra to constrain pore connectivity and the contribution of microfractures in tight carbonate reservoirs, providing a transferable approach for reservoir evaluation beyond the study area. The results categorize three rock microfacies in the study area: Bioclastic micrite, Micritic bioclastic limestone, and Sparry Bioclastic Limestone. The reservoir space is predominantly composed of secondary pores, including intragranular dissolution pores, intercrystalline clay pores, and microfractures. The pore structures exhibit a marked contrast across the lithofacies: the sparry bioclastic limestone develops the most optimal pore-fracture composite system, The pore structures exhibit a marked contrast across the lithofacies, directly correlating with hydrocarbon accumulation. Specifically, the sparry bioclastic limestone develops a pore-fracture composite system characterized by 25–100 nm pore throats, corresponding to the primary oil-bearing intervals observed in drilling. In contrast, the bioclastic micrite limestone and micritic bioclastic limestone, despite exhibiting localized nanoscale pores, lack effective connectivity (pore throats < 25 nm) and predominantly act as tight, dry layers with poor or no oil and gas shows, which endow them with the anomalous characteristic of relatively low porosity yet high permeability. This study reveals an integrated control on the development of tight bioclastic limestone reservoirs, in which sedimentary microenvironment and paleogeomorphology jointly determine the initial reservoir framework, while subsequent structural fractures and associated diagenetic dissolution play a critical role in modifying pore structures and enhancing reservoir quality. Sedimentary microfacies distribution, controlled by paleogeomorphologic variations, dictated the initial reservoir fabric. Subsequently, fracture systems generated by tectonic uplift, coupled with dissolution from meteoric freshwater leaching and organic acids, facilitated the development of secondary pores. Ultimately, the resulting optimization of the pore structure governs the final reservoir quality. The sparry bioclastic limestone is identified as the most promising exploration target in the study area. Its favorable reservoir quality is mainly attributed to its development on palaeogeomorphic and structural highs, where enhanced hydrodynamic energy and subsequent fracture-related dissolution significantly improved pore connectivity. These high-quality reservoirs are widely developed on gentle slope profiles and similar high-quality reservoirs may also locally occur at isolated palaeogeomorphic highs within steep-slope settings, as demonstrated by individual wells. Full article

Global agri-food systems face a critical conflict between the need to feed a growing population and the imperative to mitigate its substantial environmental impact, including 23% of global greenhouse gas emissions and 70% of freshwater withdrawals. This bibliometric review maps the scientific landscape of Machine Learning (ML) research applied to sustainable agri-food systems. Using a structured bibliometric protocol, we analyzed 648 scientific documents from Scopus (2010–2025) to map the evolution, collaborative networks, and thematic trends in this domain. Results reveal a field that has grown exponentially until 2021, primarily driven by contributions from Computer Science (26%) and Engineering (21%), with key publications in journals such as Computers and Electronics in Agriculture (22 papers, 2631 citations). While China and India lead in productivity (80% of top authors), high-impact research remains strongly linked to international collaborations with institutions in the U.S. and EU. Current ML efforts focus on technical optimization—such as precision irrigation, pest detection, and yield prediction—but fall short in addressing social equity and climate resilience. The study concludes that while ML holds significant promise for sustainable agri-food processing and system optimization, future progress depends on overcoming fragmented regional collaborations and integrating holistic frameworks, such as life-cycle assessment, to ensure resilient and equitable food systems. Full article

Water pollution from phenols remains a critical concern due to their persistence, toxicity, and industrial prevalence. Graphene oxide (GOx), with its functional groups and large surface area, offers strong adsorption potential. Using density functional theory (DFT), reduced density gradient (RDG), and quantitative structure–activity relationship (QSAR), we examined how protonation and substituents influence phenol adsorption. Deprotonated phenolates bind more strongly to GO than neutral species via electrostatics and H-bonding. Substituents alter affinity: halogens enhance it, bulky alkyls hinder it, and nitro groups show electron-withdrawing effects. Bisphenolate A displayed multidentate binding. QSAR models reproduced DFT energies with R² > 0.99, enabling fast prediction. These results highlight how pH speciation and substituents govern adsorption on GO, guiding the design of efficient water treatment materials. Full article

We report the first synthesis of IspH-directed prodrugs targeting the terminal enzyme of the 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway, (E)-4-hydroxy-3-methylbut-2-enyl diphosphate reductase (IspH or LytB). A series of alkyne and pyridine monophosphate cycloSaligenyl (cycloSal) prodrugs were prepared to enhance membrane permeability by masking the phosphate group. The effects of electron-withdrawing (Cl, CF₃) and electron-donating (OCH₃, NH₂) substituents were examined, together with amino acid-functionalized and mutual prodrug analogs. Among the synthesized compounds, chlorine-substituted derivatives 5c and 6c displayed the strongest antimycobacterial activity against Mycobacterium smegmatis, surpassing isoniazid in agar diffusion assays. These results indicate that electron-withdrawing substituents accelerate prodrug hydrolysis and facilitate intracellular release of the active inhibitor. This work provides the first experimental evidence of an IspH-targeted prodrug approach, highlighting the cycloSal strategy as a valuable tool for delivering phosphorylated inhibitors and developing novel antimycobacterial agents acting through the MEP pathway. Full article

Two series of tri(2-furyl)- and triphenylphosphine-gold(I) complexes, with pyridyl- and pyrimidine-thiolate ligands containing electron-donating (-CH₃) and electron-withdrawing (-CF₃) substituents were synthesized and investigated for cell viability inhibitions. Prior results indicate that several of the gold(I) complexes in these series have high antifungal properties. The observed link between antifungal and anticancer activity provided motivation to investigate their antiproliferative effects, reported here. The synthesized compounds from both series were characterized by ¹H, ¹³C, and ³¹P NMR spectroscopy, mass spectrometry (MS), infrared and UV-Vis spectroscopy, and solution stability studies. In addition, an X-ray crystallographic study was conducted on one of the gold(I) complexes. Analyte solubilities in McCoy’s 5A cell media were evaluated by ICP-MS. Initial screening studies were conducted on the two series to evaluate cell viability using the SK-BR-3 cell line. All ten gold(I) complexes exhibited sub-µM cytotoxicity and the most potent representatives, one from each series, were selected for further evaluation in four additional cell lines. Half-maximal effective concentrations (EC₅₀) were determined for the MCF7 and MDA-MB-231 malignant mammary cell lines as well as the two control cell lines, HEK293T and MCF10A, to probe for specificity. Results indicate significant selectivity towards inhibition of cancer cells compared to non-transformed for tri(2-furyl)- and triphenylphosphine-gold(I) complexes with the 3,5-dimethylpyrimidine thiolate ligand when dissolved in cell media. Additional studies including 1% DMSO as a solubilizing agent revealed its significant impact on cellular responses. Full article