Latest ArticlesAs antibiotic pollutants cannot be incompletely removed by conventional wastewater treatment plants, ultraviolet (UV) based advanced oxidation processes (AOPs) such as UV/persulfate (UV/PS) and UV/chlorine are increasingly concerned for the effective removal of antibiotics from wastewaters. However, the specific mechanisms involving degradation kinetics and transformation mechanisms are not well elucidated. Here we report a detailed examination of SO4•−/Cl•-mediated degradation kinetics, products, and toxicities of sulfathiazole (ST), sarafloxacin (SAR), and lomefloxacin (LOM) in the two processes. Both SO4•−/Cl•-mediated transformation kinetics were found to be dependent on pH (P < 0.05), which was attributed to the disparate reactivities of their individual dissociated forms. Based on competition kinetic experiments and matrix calculations, the cationic forms (H2ST+, H2SAR+, and H2LOM+) were more highly reactive towards SO4•− in most cases, while the neutral forms (e.g., HSAR0 and HLOM0) reacted the fastest with Cl• for the most of the antibiotics tested. Based on the identification of 31 key intermediates using tandem mass spectrometry, these reactions generated different products, of which the majority still retained the core chemical structure of the parent compounds. The corresponding diverse transformation pathways were proposed, involving S−N breaking, hydroxylation, defluorination, and chlorination reactions. Furthermore, the toxicity changes of their reaction solutions as well as the toxicity of each intermediate were evaluated by the vibrio fischeri and ECOSAR model, respectively. Many primary by-products were proven to be more toxic than the parent chemicals, raising the wider issue of extended potency for these compounds with regards to their ecotoxicity. These results have implications for assessing the degradative fate and risk of these chemicals during the AOPs.
Enhancement of the nonlinear optical (NLO) output power of lasers requires urgent development of an NLO crystal with a significant second-harmonic generation (SHG) response and sufficient birefringence for phase-matching capability; however, simultaneously optimizing these two key parameters remains a great challenge. In contrast to traditional single-anion units, the stereochemically-active lone pair Sb3+ ion is coordinated by S2− and I− ions to yield the mixed-anionic SbSI chalcohalide that can enhance hyperpolarizability and anisotropic polarizability concurrently. As anticipated, SbSI exhibited the largest SHG response (5.7 × AgGaS2@1.91 µm) among phase-matching Sb-based sulfides, the favorable laser-induced damage threshold (LIDT, 2.3 × AgGaS2@2.09 µm), and the giant calculated birefringence (0.62@1.91 µm). Structural analysis and computational simulations indicate that the highly polarizable mixed anion determine the enormous SHG response and birefringence.
Agrochemicals, especially plant growth regulators (PGRs), are extensively used to modulate endogenous phytohormone signals in small quantities, significantly influencing plant growth and development. Plant hormones typically exhibit diverse chemical structures, with common examples including indole rings, terpenoid frameworks, adenine motifs, cyclic lactones, cyclopentanones, and steroidal compounds, which are extensively employed in pesticides. This article explores the interactions and biological activities of small molecules on proteins, enzymes, and other reactive sites involved in the biosynthesis, metabolism, transport, and signal transduction pathways of various plant hormones. Additionally, it analyzes the structure-activity relationships (SARs) of pesticides incorporating these structural motifs to elucidate the relationship between active fragments, pharmacophores, and targets, highlighting the characteristics of potent small molecules and their derivatives. This comprehensive review aims to provide novel perspectives for the development and design of pesticides, offering valuable insights for researchers in the field.
Multiple donor-acceptor (D-A) combinations represent a promising category of thermally activated delayed fluorescence (TADF) materials, offering potential for superior efficiency and stability. However, current systems are predominantly composed of limited donor groups, primarily carbazole-based derivatives. In this work, we developed a series of D-A type materials incorporating helical π-expanded carbazole (CzNaph) and 7H-dinaphtho[1,8-bc:1′,8′-ef]azepine (AzNaph), alongside traditional carbazole, ranging from mono- to tetra-substituted configurations (Dn-A). Through systematic investigation of geometric and electronic structures, the number and positioning of multiple donors are confirmed with significant manipulations on charge transfer characteristics and the S1 state via steric effects. Density functional theory (DFT) calculations reveal that varying the number of π-extended donors within the acceptor framework produces emission colors from ultraviolet to red, providing a diverse range of emitters. Furthermore, the reduced reorganization energy of S1 observed in tetra-substituted Cz and CzNaph, as well as MonoAzN, indicates lower structural relaxation, highlighting these materials' potential as stable luminescent candidates. This study underscores the importance of diverse composing units in achieving efficient and stable TADF emitters with multiple and hetero-donor configurations.
Cobalt sulfide has received widespread attention in the advanced oxidation treatment of wastewater, and its catalytic activity is influenced by crystal structure and exposed active sites. This work successfully constructed three types of cobalt sulfides, namely Co9S8, Co3S4 and CoS2, by changing the molar ratio of cobalt to sulfur. The results showed that the degradation efficiency of Co9S8, Co3S4 and CoS2 on chloroxylenol by activated peroxomonosulfate (PMS) were 100%, 88.70% and 67.73%, respectively. Combined with density functional theory (DFT), the structural properties and reaction energy barriers of different cobalt-sulfur ratios were calculated. As the ratio of cobalt to sulfur increases, the sulfur vacancies realized a fuller exposure of active sites (Co2+surf.) on the surface of the catalysts, with a highly linear relationship with the reaction rate constant (R2 = 0.945). This work explores the structure-activity relationship between cobalt sulfur ratio and degradation efficiency, which can guide new catalyst synthesis.
Hyperforatone A (1), the 1,8-seco rearranged polycyclic polyprenylated acylphloroglucinol, possessed an unusual bicyclo[5.4.0]undecane skeleton bearing a 5/7/6/5 ring system, and two known biosynthetically related precursors (2 and 3) were isolated from Hypericum perforatum (St. John’s wort). The structure and absolute configuration were unambiguously confirmed by a combination of comprehensive spectroscopic data, computational methods including residual dipolar couplings (RDCs), and X-ray crystallography. Density functional theory (DFT) calculations revealed that the cationic cyclization reaction was key to proposed formation mechanism for hyperforatone A. Furthermore, in vitro and in vivo experiments demonstrated that compound 1 was a potential anti-neuroinflammatory agent.
Electrocatalytic reduction of NO (NORR) is an effective method for NH3 synthesis, due to low bonding energy of NO bond. In this work, we have investigated many CrS2 based catalysts, including pristine CrS2, CrS2 with one S vacancy (v-CrS2), and Ti doped CrS2 (Ti@CrS2). The results have shown that the pristine CrS2 exhibits inert character for NO activation. However, v-CrS2 and Ti@CrS2 can exhibit enhanced interaction with NO, due to increased charge transfer between NO and substrates (0.52–0.75 e) and enhanced adsorption energies of NO on the catalysts (-0.96~-1.64 eV), compared to the situation of CrS2 (0.065 e/-0.30 eV). From the free energy profiles of NO electro-reduction to NH3, we can see that the v-CrS2 and Ti@CrS2 all exhibit ultralow limiting potentials of -0.03~-0.47 V, following both *NOH and *NHO mechanisms. Therefore, introducing vacancy and doping are all promising modification strategies for NORR catalysts. The results have provided a new idea for the search of catalysts for efficient electrocatalytic reduction of NO.
A general process for the construction of azaaryl alkanes was achieved by employing the photoredox/palladium dual catalysis under mild visible light irradiation. The palladium catalyst ligated with a diphosphamide ligand exhibited high effectiveness in facilitating the modular three-components transformation. Furthermore, the cascade transformation was not restricted to constructing tertiary carbon centers; it also encompassed the synthesis of more challenging quaternary carbon centers with sixteen representative azaarene-derived substrates as reactants. In addition, alkyl 1,4-dihydropyridines (DHP), alkyl BF3K, and alkyl carboxylic acids were identified as precursors for alkyl radicals. Mechanistic investigations revealed the involvement of two different active benzylic nucleophiles in the cascade transformation. One is azabenzylic radical, which generate the terminal product through an “inner sphere” reductive elimination process. The other is azabenzylic anions, generated through visible light induced radical anion cross-over, leading to the formation of terminal products via an “outer sphere” reaction pathway. The efficiency of current modular transformation was also demonstarted by the concise of oliceridine, a prominent USFDA drug for pain management.
Polyetheretherketone (PEEK) is a desirable candidate to replace conventional metal implants owing to its excellent mechanical properties. However, the intrinsic bioinertness of PEEK results in inferior or delayed osseointegration, which limits its further clinical application. To address these challenges, one leading strategy is to construct a biofunctionalized surface on PEEK that provides a coordinated osteoblast-osteoclast interactions microenvironment. Herein, alendronate (ALN), a common bone absorption inhibitor, was loaded in biomedical inorganic/organic microspheres, consisting of bioactive inorganic nano-hydroxyapatite core, and chitosan (CS) shell. Polydopamine (PDA) modification was employed to ensure the adherence of the microspheres to the PEEK surface. The delivery of ALN and Ca2+ from these microspheres simultaneously suppressed osteoclastogenesis and promoted osteogenesis, resulting in a coordinated cascade of osteoblast-osteoclast interactions crucial for the per-implant osseointegration. In vitro experiments demonstrated that the PEEK surface exhibited satisfactory biocompatibility and enhanced the proliferation and osteogenic differentiation of rat bone mesenchymal stem cells while inhibiting the osteoclast differentiation. Moreover, the in vivo rat femoral drilling model demonstrated superior osseointegration three months after implantation. By considering the bone remodeling processes, this study proposes a novel biofunctionalized PEEK surface that regulates the activities of both osteoblasts and osteoclasts to promote osseointegration.
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