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The sensitivity of solid state nuclear magnetic resonance spectroscopy can be enhanced via dynamic nuclear polarization (DNP) using unpaired electrons as polarizing agents. In metal ions based (MI)-DNP, paramagnetic metal ions are introduced as dopants into inorganic materials serving as endogenous polarizing agents. Having polarizing agents as part of the structure enables signal enhancements within the bulk of the material. Nuclear spins can be hyperpolarized either directly through their coupling to the polarizing agent or via homonuclear spin diffusion. In this work, we addressed what are the factors determining the relative sizes of the spin pools polarized by each of these two mechanisms and how changing their contribution to the polarization process affects the experimental outcome. Experimentally, we adjusted the spin diffusion rate through modifying the isotope ratio 6Li/7Li in otherwise identical samples, Li4Ti5O12 doped with paramagnetic Fe(III). DNP experiments on samples with typical content of polarizing agents for MI-DNP, corroborated by simulations, evidenced that while the efficiency of spin diffusion has large effects on the polarization buildup times, the enhancements remain largely unaffected. [ABSTRACT FROM AUTHOR]

A survey of the literature and the Cambridge Structural Database reveals thirty nine p-tert-butylcalix[8]arene-supported transition (3d, limited to V–Cu) and lanthanide metal complexes ranging in nuclearity from one to eighteen, twenty of which are homometallic and nineteen of which are heterometallic. We provide a review of the coordination chemistry of these complexes, including our own work in the area. We also provide our thoughts and perspectives on the common structural themes observed, identify gaps in knowledge and evaluate how that may inform and direct future synthetic efforts. What is clear is that the coordination chemistry of H8TBC[8] with paramagnetic metal ions remains hugely underexplored. [ABSTRACT FROM AUTHOR]

Engineering the surface of metal halide perovskite nanocrystals (MHPNCs) is crucial for optimizing their optical properties, repairing surface defects, enhancing quantum yield, and ensuring long-term stability. These enhancements make surface-engineered MHPNCs ideal for applications in light-emitting devices (LEDs), displays, lasers, and photodetectors, contributing to energy efficiency. This article delves into an introduction to MHPNCs, their structure and types, particularly the ABX3 type (where A represents monovalent organic/inorganic cations, B represents divalent metal ions mainly Pb metal, and X represents halide ions), synthesis methods, unique optical properties, surface modification techniques using various agents (particularly inorganic molecules/materials, organic molecules, polymers, and biomolecules) to tune optical properties and applications in the aforementioned light-emitting technologies, challenges and opportunities, including advantages and disadvantages of surface-modified APbX3 MHPNCs, and a summary and future outlook. This article explores surface modification strategies to improve the optical performance of MHPNCs and aims to inspire advancements in light emitting applications. Importantly, the challenges and opportunities section of this article will illuminate the path to overcoming obstacles, providing invaluable insights for researchers in this field. This in-depth review explores the surface engineering of MHPNCs for light-emitting applications, highlighting their notable advantages and addressing ongoing challenges. By delving deep into various surface modification strategies, this article aims to revolutionize MHPNC-based light-emitting applications, setting a new benchmark in the field. This paves the way for revolutionary advancements, maximizing the capabilities of surface-engineered MHPNCs and heralding a transformative era in precise light-emitting research. [ABSTRACT FROM AUTHOR]

In the electro-Fenton system, prolonged operation of the electro-Fenton catalyst can lead to the accumulation of significant amounts of Fe3+, resulting in concentration polarization phenomena that inhibit the progression of the electro-Fenton reaction, thereby adversely affecting the chemical mechanical polishing of GaN. This study introduces non-ferrous metal ions (Mn2+/Cu+/Ce3+) into the conventional electro-Fenton system, which primarily utilizes Fe2+ as the catalytic ion. By leveraging the principles of galvanic cells and Fenton-like reactions, we accelerate the electron exchange among different metal ions, thus enhancing the instantaneous concentration rate of electro-Fenton catalytic ions and the oxidation rate of GaN. Through tribological experiments involving GaN, it is evident that bi-metallic micro-electrolytic catalysts achieve a higher catalytic oxidation efficiency compared to their monometallic counterparts. Notably, the combination of Fe2+ and Ce3+ exhibits the most pronounced synergistic effect. This provides valuable insights for the design of composite catalytic media within the electro-Fenton framework. [ABSTRACT FROM AUTHOR]

Amination of styrene-divinylbenzene (SDVB) copolymers is a traditional process for preparing strong anion exchange resins that can greatly improve their performance and applications. In the present investigation, poly(styrene-co-divinyl benzene) copolymers functionalized by various amino groups were synthesized by the amination route. The performance of synthesized exchange resins for the separation and recovery of active Mo(VI) and I(I) isotopes from their aqueous solutions was compared to that of three commercial ion exchange resins, used in the actual production of these radioisotopes in the Radioisotopes Production Facility. The morphology and structural properties of the synthesized copolymers as well as the commercial reference resins were characterized using FT−IR, SEM, TG, and XPS. The results demonstrate that the copolymer was successfully functionalized with amino groups, where trimethylamine produced amination greater than triethylamine. Furthermore, the thermal stability of synthesized anion exchanges was significantly higher than that of commercial beads. The synthesized polymer networks presented excellent radiation stability under applied experimental conditions. Compared to the reference resins, the synthesized co-polymeric beads showed enhanced adsorption capability for MoO42− and I− ions from an aqueous solution. Further, the uptake affinity of the networks aminated with trimethylamine for both radioisotopes, in optimal conditions, was greater than that of triethylamine aminated beads. The sorption mechanism was inferred through FT−IR and XPS analysis, and the results clarified that the separation of both radioisotopes was substantially related to the amine functional groups on the resin framework. The spectroscopic analysis illustrated that one molybdenum ion (in the form of MoO42−) was subjected to an ion-exchange interaction and two Cl− ions in the amine resin. A similar exchange mechanism was predicted for I− with Cl− ions. Further, the enhanced sorption of Mo(VI) could be additionally attained through coordination interactions with N atoms in the amine groups that have good chelating capability toward metal ions. The reusability performance of the synthesized exchange resins is better than that of the commercial reference resins, where they could be effectively regenerated for up to five cycles. Finally, this study presents a new technique for the separation and recovery of Mo(VI) and I(I) from irradiated low-enriched U-targets by employing highly promising amino-modified polystyrene-divinyl benzene microspheres. [ABSTRACT FROM AUTHOR]

[Display omitted] Photocatalysis, which uses sunlight, N 2 and H 2 O to produce NH 3 , is a more sustainable approach to N 2 fixation than the Haber-Bosch process. However, its efficiency is severely limited by the difficulty of activating N N bonds. This work presents metal (M = Cu, Fe, V)-substituted MIL-125(Ti) (MIL-(MTi)) for photocatalytic N 2 fixation without using any sacrificial agents. Structural characterizations reveal that the active sites including oxygen vacancies (OV) and Ti3+ species are formed by the resulting crystal distortion due to the partial substitution of Ti4+ by other metal ions (Cu+, Fe2+, V3+) in MIL-125(Ti). MIL-(CuTi) possesses a larger number of OV and Ti3+ compared to MIL-(FeTi) and MIL-(VTi) due to the larger valence difference between Cu+ and Ti4+. These active sites not only promote the adsorption and activation of N 2 and H 2 O, but also facilitate the photogenerated charge mobility. Photogenerated holes oxidize H 2 O to produce O 2 and H+. Photogenerated electrons reduce N 2 activated on Ti3+ sites by combining with H+ to form NH 4 +. Therefore, MIL-(CuTi) shows the highest NH 4 + production rate 46.5 µmol·h−1·g−1, which is much higher than that (1.2 µmol·h−1·g−1) of the pristine MIL-125(Ti). This work provides a new insight into rational design for artificial N 2 fixation systems by the construction of the active site. [ABSTRACT FROM AUTHOR]

Metal ion pollution poses a global concern due to its significant risks to both human health and environmental well-being. The toxicity of these ions can increase when they coexist, interacting with each other and with other harmful substances, even at low concentrations. Therefore, an accurate, rapid, and cost-effective methodology is urgently needed for the simultaneous quantification of multiple metal ions. This study presents a new approach for the multiplexed detection of various metal ions (Ag+, Cu2+, Hg2+, Al3+, Pb2+, Fe3+, Fe2+, Zn2+, Ni2+, Cd2+, and Ca2+) using a triple-emission nanoprobe comprising carbon dots and distinctly capped CdTe quantum dots, specifically green-emitting glutathione -quantum dots and red-emitting 3-mercaptopropionic acid-quantum dots. The method achieved high accuracy by analysing first- and second-order photoluminescence data with distinct advanced chemometric tools. R2P values for partial least squares and unfolded partial least square models exceeding 0.9 for several metal ions at low concentrations (mmol L−1) were obtained. Additionally, PL second-order data yielded significantly better results than PL first-order data, attributed to the distinct behaviour of the metal ions over time. Interestingly, it was also noted for the first time the significant contribution of the molar ratio between the metal ions on the models' accuracy. This novel method provides a highly accurate and efficient way to detect multiple metal ions simultaneously, paving the way for improved environmental monitoring and pollution assessment. The utilization of the proposed method contributes to a better understanding of the complex interactions in mixed metal ion systems, allowing for earlier detection and mitigation of metal ion contamination threats. [ABSTRACT FROM AUTHOR]

AbstractCopper mine drainage typically contains large quantities of heavy metal ions and sulfate (SO42-) contaminants. Among various strategies for treating acid mine drainage (AMD), using anaerobic bioreactors for biological removal has proven to be particularly effective. This study aimed to assess the efficiency of sulfate-reducing bacteria (SRB) in AMD treatment. To achieve this, a semi-pilot-scale down-flow fluidized bed (DFFB) anaerobic reactor was employed to remove SO42– and copper (Cu), while a robust numerical model was developed to evaluate the reactor’s performance. The initial concentrations of Cu and SO42– in the waste stream were 20 and 3900 mg/L, respectively. At an optimal retention time of 24 h, the maximum removal efficiencies reached 98.05% for Cu and 98.38% for SO42-. The treatment process also increased the effluent’s alkalinity and effectively neutralized acidity, providing substantial environmental benefits. Notably, the reactor exhibited stable performance across six consecutive cycles, which can be attributed to the inclusion of activated carbon (AC) granules in the reactor bed. Consequently, the biological approach used here offers a promising, cost-effective, and environmentally sound method for AMD treatment. Finally, computational fluid dynamics (CFD) simulations were conducted to model the reactor, and their outputs showed excellent agreement with experimental data, underscoring the significant potential of this approach for large-scale industrial applications. [ABSTRACT FROM AUTHOR]

A biphasic system composed of two deep eutectic solvents (DES) sharing a common hydrogen-bond donor exhibits a tuneable phase behavior and efficient metal partitioning, yielding an improved separation selectivity of trivalent from divalent metal ions compared to the equivalent aqueous system. [ABSTRACT FROM AUTHOR]

The naked-eye detection of hazardous pollutants through simple and cost-effective techniques is of great interest to the scientific community and related stakeholders in analytical science. The present study emphases the development of a stimuli-responsive probe by encountering sophisticated techniques for the detection of environmental pollutants. Herein, highly swellable and fluorescent-WTR-CDs-loaded HB-Alg/Gel@WTR-CDs was fabricated through a simple extrusion dripping method. The fluorescent WTR-CDs-loaded composite hydrogel showed rapid (within 10–15 min) naked-eye detection with high selectivity and sensitivity towards Cr6+ and Mn7+ ions over other metal ions. The developed probe had a linear detection range of 0–10 μg mL−1 with a detection limit of 0.28 μg mL−1 and 0.30 μg mL−1 for Cr6+ and Mn7+ ions, respectively. Interestingly, the hydrogel-based fluorescent sensor enabled on-site naked-eye detection of real water samples with good recovery. Additionally, the recyclability and reusability approach were employed for the removal of model pollutant dyes with Alg/Gel-carbon, which was synthesized using spent hydrogel beads after sensing. The present study demonstrates the tremendous potential applications of HB-Alg/Gel@WTR-CDs for simple, low-cost and fast visual detection of environmental pollutants. According to the analytical greenness evaluation (AGREE), the developed analytical method is green with an AGREE score of 0.81 and an ecofriendly circular-economy approach. [ABSTRACT FROM AUTHOR]

In this study, thalli nitrogen (N) and metal ions contents in the two fruticose lichens (Ramalina intermedia and Usnea cornuta) were quantified, which were collected from a pristine Himalayan forest of Shey Phoksundo National Park of western Nepal. Besides, the probable impacts of N and metal ions in physicochemical responses such as electrical conductivity, chlorophyll contents, and chlorophyll degradation were studied. Our initial hypothesis was there are considerable amounts of thallus N and metal ions in lichens from the study area, and it has substantial impacts on physicochemical responses. In comparison, the thalli N concentration was observed to be the greatest in R. intermedia thalli (0.24%–1.15%). However, comparable amounts of metal ions in both lichen species were observed. Regression analysis revealed the least or no impacts of N and metal ions in physicochemical responses. The principal component analysis suggests the contribution of different environmental variable and their correlation with lichen's variables. This study provides evidence of the least concentration of N and metal ions and only minor impacts on the physicochemical integrity of the two sensitive lichens in our study area. This study is likely to contribute as field‐based reference information for further studies on the species‐specific N and metal ions accumulation in lichens from different Himalayan forest systems to monitor ecosystem health. [ABSTRACT FROM AUTHOR]

Despite all the advancements in aqueous synthesis of gold nanoparticles, certain features like one-pot/one-step method with minimal reactants using greener solvents are still demanding. The challenge in the aqueous phase synthesis is to balance the nucleation and precise growth of nanoparticles avoiding aggregation. In this work, we report a unique versatile unexplored molecule aminosalicylate sodium (Na-4-ASA) which functions as a capping, reducing, stabilizing and more interestingly as an encapsulating agent for gold nanoparticles. This multi-faceted molecule showed excellent control in synthesizing monodisperse tunable encapsulated nanoparticles of sizes (60 nm, 53 nm and 12 nm) exhibiting absorbance bands at 560 nm, 540 nm and 520 nm respectively. X-ray diffraction and Fourier Transmission Infra-Red validated crystalline structure and binding of Na-4-ASA onto gold nanoparticles surface respectively. Furthermore, the AuNPs were investigated for their ability to detect metal ions through colorimetric change where purification via centrifugation turned out to be a key parameter in enabling the detection. Selectivity towards Al3+ was observed with the 12 nm sized nanoparticles at 0.5 ppm metal ion concentration. The AuNPs of sizes 60 nm and 53 nm detected Al3+/Cr3+/Fe3+ and Al3+/Fe3+ respectively indicating the impact of size in heavy metal ions detection. The greater the size of AuNPs, lower is the selectivity where detection of three metal ions were observed and vice versa i.e. smaller-sized AuNPs showed high selectivity by detecting single metal ion. Also, the time duration for detection increased with decreasing size of the AuNPs. Finally, LOD for the heavy metal ions Al3+, Cr3+, and Fe3+ were calculated as 67 ppb, 78 ppb, 76 ppb respectively. [ABSTRACT FROM AUTHOR]

In terms of safety and emergency response, identifying hazardous gaseous acid chemicals is crucial for ensuring effective evacuation and administering proper first aid. However, current studies struggle to distinguish between different acid vapors and remain in the early stages of development. In this study, we propose an on-site monitorable acid vapor decoder, MOF-808-EDTA-Cu, integrating the robust MOF-808 with Cu-EDTA, functioning as a proton-triggered colorimetric decoder that translates the anionic components of corrosive acids into visible colors. The sensor exhibits a cyan-to-yellow shift when exposed to HCl vapor and can visually differentiate various acidic vapors (HF, HBr, and HI) through unique color changes. Furthermore, the compatibility of the MOF-based sensor with multiple metal ions having atomic-level dispersion broadens its discrimination range, enabling the identification of six different colorless acid vapors within a single sensor domain. Additionally, by incorporating a flexible polymer, the MOF-808-EDTA-Cu has been successfully processed into a portable miniaturized acid sensor, exhibiting distinct color changes that can be easily monitored by the naked eye and camera sensors. This provides experimental validation as a practical sensor capable of on-site 24-hour monitoring in the real world. Identifying hazardous acid vapors is crucial for safety and emergency response. This study reports on-site monitorable MOF-based acid vapor sensors capable of translating diverse anionic components of corrosive acids into distinct visible color changes. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) metal-organic frameworks (MOFs) have been extensively utilized across various research areas. However, the application of 2D MOF-based membranes for the removal of heavy metal ions remains largely unexplored, despite their potential as suitable candidates due to their inherent porosity. In this study, we employed molecular dynamics (MD) simulations to investigate the capacity of a typical 2D MOF, Cu-THQ, for the separation of heavy metal ions, including Cd²⁺, Cu²⁺, Hg²⁺, and Pb²⁺. Our MD results demonstrate that single-layered Cu-THQ MOF membranes exhibit excellent performance in heavy metal ion removal, with nearly 100% ion rejection while also allowing high water permeability. Free energy calculations confirm that water transport through the Cu-THQ membrane is energetically more favorable compared to the transport of heavy metal ions. Further simulations of multilayered Cu-THQ membranes indicate that increasing the number of Cu-THQ MOF layers hinders water molecule transport, resulting in a reduction in water permeability due to a more widespread adsorption, that is primarily driven by electrostatic interactions within the membrane pores. Therefore, our simulations not only identify a promising MOF membrane candidate for efficient heavy metal ion removal but also suggest an optimal MOF construction scheme, which provide beneficial information for future applications in the sieving field. [ABSTRACT FROM AUTHOR]

Two‐dimensional conjugated metal–organic frameworks (2D c‐MOFs) have shown great promise in various electrochemical applications due to their intrinsic electrical conductivity. A large pore aperture is a favorable feature of this type of material because it facilitates the mass transport of chemical species and electrolytes. In this work, we propose a ligand insertion strategy in which a linear ligand is inserted into the linkage between multitopic ligands, extending the metal ion into a linear unit of ‐M‐ligand‐M‐, for the construction of 2D c‐MOFs with large pore apertures, utilizing only small ligands. As a proof‐of‐concept trial of this strategy, a 2D c‐MOF with mesopores of 3.2 nm was synthesized using commercially available ligands hexahydrotriphenylene and 2,5‐dihydroxybenzoquinone. The facilitation of the diffusion of redox species by the large pore size of this MOF was demonstrated through a series of probes. With this feature, it showed superior performance in the electrochemical analysis of a variety of biological species. [ABSTRACT FROM AUTHOR]