High-Performance Aqueous Zn2+/Al3+ Electrochromic Batteries based on Niobium Tungsten Oxides

Electrochromic energy storage devices (EESDs) are incorporating electrochromic and energy storage functions, which can visually display energy storage levels in real-time to promote the next generation of transparent battery development. However, their performances are still limited for practical applications. Herein, a self-powered EESD based on complex niobium tungsten oxide is designed using aqueous Zn²⁺ and hybrid Zn²⁺/Mⁿ⁺ (Mⁿ⁺ = Al³⁺, Mg²⁺, and K⁺) electrolytes. The results reveal that the use of Zn²⁺/Al³⁺ hybrid electrolyte achieves superior electrochromic performances including a short self-coloring time, high optical contrast, and excellent cyclic stability. Furthermore, it is also found that the self-coloring process is accompanied by a high discharged capacity of niobium tungsten oxide, with high optical modulation in the Zn²⁺/Al³⁺ hybrid electrolyte. The detailed mechanism on the performances of EESD using various electrolytes is systematically studied. This work provides a simple and effective strategy for an aqueous and self-powered EESD with high optical contrast and good cycle stability.     

Thiophene-2,5-diesters as electrochromic materials: The effect of ester groups on the device performance and stability

A series of thiophene-2,5-dicarboxylic acid diesters (R–Th, compounds 3–9) with linear and branched alkyl (3–7) and benzyl (8,9) ester groups have been synthesized and characterized by ¹H/¹³C NMR and MS. Their electrochemical reduction in cyclic voltammetry experiments proceed as two-step single-electron transfer process to form radical anions R–Th^•– (at −1.87 … −2.00 V vs Ag/Ag⁺) and dianions R–Th^2– (at −2.48 … −2.68 V vs Ag/Ag⁺). In spectroelectrochemical experiments in Bu₄NClO₄/N,N-dimethylformamide electrolyte solution, all compounds exhibit reversible color changes from colorless in their neutral state to blue colors in the reduced state, with two characteristic absorptions of radical anions R–Th^•– in the short-wavelength (ca. 406–420 nm) and long-wavelength regions (ca. 610–655 nm). The L*a*b* CIE color coordinates of th e sandwich-type electrochromic devices have been evaluated by colorimetry measurements and the devices demonstrated good coloration efficiency of up to 512 cm² C⁻¹. The cycling stability of the materials on electrochromic coloring/bleaching substantially depends on the structure of the R ester groups and increased with increasing the steric hindrances in the R. In the series of seven studies compounds, the best cycling stability was observed for R = 2-ethylhexyl and benzyl. The degradation mechanism during electrochromic cycling in an inert atmosphere (under nitrogen) and in air is discussed.     

Coupling Uniform Pore Size And Multi‑Chemisorption Sites: Hierarchically Ordered Porous Carbon For Ultra-Fast And Large Zinc Ion Storage

Constructing hierarchically ordered macro/meso−microporous structures of carbonaceous cathode with matchable pore size and adequate active sites is significant toward large Zn²⁺ storage, but remains a formidable challenge. Herein, a new perspective is reported for synthesizing phosphorus and nitrogen dual-doped hierarchical ordered porous carbon (PN-HOPC) by eliminating the micropore confinement effect and synchronously introducing multi-chemisorption sites. The interconnected macropore can effectively facilitate long-distance mass transfer, and meso−microporous wall can promote accessibility of active sites. Density functional theory (DFT) calculations identify that the P and N co-doping markedly contributes to the reversible adsorption/desorption of zinc ions and protons. Consequently, the optimized PN-HOPC exhibits outstanding Zn²⁺ storage capabilities in terms of high capacity (211.9 mAh g⁻¹), superb energy density (169.5 Wh kg⁻¹), and ultralong lifespan (99.3% retention after 60 000 cycles). Systematic ex situ measurements integrating with in situ Raman spectroscopy and electrochemical quartz crystal microbalance (EQCM) techniques elucidate that the superior electrochemical capability is ascribed to the synergistic effect of the Zn²⁺, H⁺, and SO₄²⁻ co-adsorption mechanism, as well as invertible chemical adsorption. This study not only provides new insights to design advanced carbon materials toward practical applications but also sheds lights on a deeper understanding of charge storage mechanism for zinc-ion capacitors (ZICs).     

Amorphization Boost Multi-Ions Storage for High-Performance Aqueous Batteries

Regarding the complex properties of various cations, the design of aqueous batteries that can simultaneously store multi-ions with high capacity and satisfactory rate performance is a great challenge. Here an amorphization strategy to boost cation-ion storage capacities of anode materials is reported. In monovalent (H⁺, Li⁺, K⁺), divalent (Mg²⁺, Ca²⁺, Zn²⁺) and even trivalent (Al³⁺) aqueous electrolytes, the capacity of the resulting amorphous MoO_x is more than quadruple than that of crystalline MoO_x and exceeds those of other reported multiple-ion storage materials. Both experimental and theoretical calculations reveal the generation of ample active sites and isotropic ions in the amorphous phase, which accelerates cation migration within the electrode bulk. Amorphous MoO_x can be coupled with multi-ion storage cathodes to realize electrochemical energy storage devices with different carriers, promising high energy and power densities. The power density exceeded 15000 W kg⁻¹, demonstrating the great potential of amorphous MoO_x in advanced aqueous batteries.     

Nanostructured TiO2 modified with acetohydrazide zinc porphyrin well-arrays for supramolecular solar cells

In this work, employing the metal-mediated assembling strategy for organizing acetohydrazide zinc porphyrin (ZnP) and different organic acid (Ai) ligands on the nanostructured TiO₂ electrode surfaces have been prepared, wherein the ZnP and Ai units are bound by a series of differently bivalent metal ions (M, M = Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺ and Hg²⁺), resulting in a ZnP–M–Ai assembled approach. The photovoltaic performances of these assemblies-sensitized solar cells were performed under irradiance of 100 mW cm⁻² AM 1.5G sunlight. A significantly improved conversion efficiency of ZnP–Mn–A5 and ZnP–Cd–A5 devices occurs, indicating well-ordered arrangements of ZnP molecules on the TiO₂ electrode surfaces for ZnP–Mn–A5 and ZnP–Cd–A5, where A5 is a pyridine–monocarboxylic acid ligand bearing longer arm. The results were also verified by the HOMO–LUMO gaps, UV–vis and fluorescence spectra.     

Water‐Induced Phase Separation Forming Macrostructured Epitaxial Quartz Films on Silicon

Quartz has been widely used as a bulk material in optics, the microelectronic industry, and sensors. The nanostructuring and direct integration of oriented quartz crystals onto a semiconductor platform has proven to be challenging. However, here, a new approach is presented to integrate epitaxial quartz films with macroperforations within the range of 500 nm and 1 μm using chemical solution deposition. This method constitutes an appealing approach to develop piezoelectric mass sensors with enhanced resonance frequencies due to the thickness reduction. Perforated quartz films on (100)‐silicon are prepared from amorphous silica films deposited via dip‐coating and doped with metal cations that catalyze quartz crystallization. The metal cations are also active in the formation of the macroperforations, which arise due to a phase separation mechanism. Cationic surfactant–anion–metal cation assemblies stabilize droplets of water, creating an indentation in the hydrophilic silica matrix which remains after solvent evaporation. Many cations induce phase separation, including Li⁺, Na⁺, Sr²⁺, Mn²⁺, Fe²⁺/Fe³⁺, Ca²⁺, Ce³⁺ and La³⁺ but only the Sr²⁺ and Ca²⁺ cations in this series induce the epitaxial growth of α‐quartz films under the conditions studied. The combination of sol–gel chemistry and epitaxial growth opens new opportunities for the integration of patterned quartz on silicon.     

Synthesis of nickel–zinc–yttrium ferrites: Structural elucidation and dielectric behavior evaluation

Novel Ni_0.6Zn_0.4Y_2xFe_2−2xO₄ soft spinel ferrites were prepared via double sintering ceramic route. The influence of Y³⁺ cations on structural, morphological, electrical and dielectric properties was investigated. X-ray diffraction (XRD) confirmed the formation of single phase spinel structure for 0≤x≤0.06 and thereafter a small peak of orthorhombic phase (FeYO₃) appeared for x>0.06. The incorporation of yttrium altered the lattice constant. The variation in lattice constant with respect to the Y³⁺ contents was non-linear. The variation of lattice constant may be attributed to larger ionic radius of Y³⁺ as compare to Fe³⁺ cations and solubility limit of substituted cations. Fourier transform infrared (FTIR) spectra showed two strong absorption bands around 600 cm⁻¹ and 400 cm⁻¹ which confirmed the spinel structure. The dc electrical resistivity was found to increase from 5.67×10⁵ to 8.48×10⁸ Ω cm with the increased Y³⁺ contents. The dielectric constant and dielectric loss tangent were significantly impeded by increasing the yttrium contents. The optimized electrical resistivity and reduced dielectric parameters suggest the possible use of these ferrites in the fabrication of microwave devices.     

Interlayer Injection of Low-Valence Zn Atoms to Activate MXene-Based Micro-Redox Capacitors With Battery-Type Voltage Plateaus

Insufficient and unstable energy output is the bottleneck issue radically restricting the application of micro-supercapacitors (MSCs). Herein, an interlayer atom injection strategy that can anchor low-valence Zn atoms (Zn^δ+, 0 < δ <2) on O-terminals of Ti₃C₂T_x (MXene) flakes within the MXene/silver-nanowires hybrid cathode of symmetric MSCs is first presented. Combining the polyacrylamide/ZnCl₂ hydrogel electrolyte rich in Cl⁻ and Zn²⁺ ions, the matched Zn^δ+/Zn²⁺ (−0.76 V vs SHE) and Ag/AgCl (0.23 V vs SHE), redox couples between the symmetrical electrodes are activated to offer faradaic charge storage beside ions-intercalation involved pseudocapacitance. Thus, a battery-type voltage plateau (≈0.9 V) appears in the discharge curve of a fabricated pseudo-symmetric micro-redox capacitor, simultaneously achieving energy density enhancement (117 µWh cm⁻² at 0.5 mA cm⁻²) and substantially improved power output stability (46% of the energy from the plateau region) relative to that before activation (98 µWh cm⁻² without voltage platform). The work provides a fire-new strategy to overcome the performance bottlenecks confronting conventional MSCs.     

Sulfur Mismatch Substitution in Layered Double Hydroxides as Efficient Oxygen Electrocatalysts for Flexible Zinc–Air Batteries

Although layered double hydroxides (LDHs) are extensively investigated for oxygen electrocatalysis, their development is hampered by their limited active sites and sluggish reaction kinetics. Here, sulfur mismatch substitution of NiFe–LDH (S–LDH) is demonstrated, which are in-situ deposited on nitrogen-doped graphene (S–LDH/NG). This atomic-level sulfur incorporation leads to the construction of the tailored topological microstructure and the modulated electronic structure for the improved catalytic activity and durability of bifunctional electrocatalysts. The combined computational and experimental results clarify that the electron transfer between the sulfur anion and Fe³⁺ generates the high-valence Fe⁴⁺ species, while the mismatch substitution of the sulfur anion induces the metallic conductivity, an increased carrier density, and the reduced reaction barrier. Consequently, the as-fabricated Zn–air battery achieves a high power density of 165 mW cm^-2, a large energy density of 772 Wh kg_Zn^-1 at 5 mA cm^-2, and long cycle stability for 120 h, demonstrating its real-life operation.     

Structure and magnetic properties evolution of cobalt–zinc ferrite with lithium substitution

Li_xCo_0.5Zn_0.5−xFe₂O₄ (0.0≤x≤0.3) is obtained by calcining precursor oxalates at 900 °C in air. The precursor and its calcined products are characterized by thermogravimetry and differential scanning calorimetry, X-ray powder diffraction, scanning electron microscopy, and vibrating sample magnetometer. A high-crystallized Li_xCo_0.5Zn_0.5−xFe₂O₄ with a cubic structure is obtained when the precursor is calcined at 900 °C in air for 3 h. Lattice parameters decrease with the increase of Li⁺ addition amount. The magnetic properties of Li_xCo_0.5Zn_0.5−xFe₂O₄ depend on Li⁺ doped amount and calcination temperature. Li_0.3Co_0.5Zn_0.2Fe₂O₄ obtained at 900 °C has the highest specific saturation magnetization value, 70.24 emu/g. However, Li_0.3Co_0.5Zn_0.2Fe₂O₄ obtained at 800 °C has the highest remanence (8.29 emu/g) and coercivity value (97.8 Oe).     

Naked-eye detection and sustainable removal of zinc ions in water by a conjugated polymer with ratiometric absorption

A conjugated polymer with ratiometric absorption, namely poly-deca-4,6-diynedioic acid (PDDA), has been developed for the naked-eye detection of zinc ions (Zn²⁺) in water samples. This probe possesses both excellent Zn²⁺ selectivity and great sensitivity based on the absorption ratio change of PDDA upon the addition of Zn²⁺. The water-soluble PDDA is able to detect Zn²⁺ in the pH range of 6.4–10.4, and the detection of Zn²⁺ by PDDA is not affected by the presence of other metal ions and anions. PDDA appears yellow with a maximal absorption at 468 nm, and shows a significant color change from yellow to orange when Zn²⁺ reaches 1.0 mg/L (the national standard of China), and to pink color when Zn²⁺ reaches 3.0 mg/L (the World Health Organization recommended level). Notably, PDDA also serves as a reusable adsorbent to effectively remove Zn²⁺ in water samples, with an average recovery rate of 97.75% for PDDA and a removal efficiency of 84.54% for Zn²⁺. PDDA herein represents an unprecedented probe integrating the rapid and accurate naked-eye identification of Zn²⁺, as well as the efficient and sustainable removal of Zn²⁺ in water media.     

Star-shaped self-assembly of an organic thin film transistor sensor in the presence of Cu2+ and CN− ions

In this study we developed organic thin film transistors (OTFTs) for the sensing of metal ions and anions through the self-assembly of a pentacene/Schiff base pyrene derivative. Our bilayer OTFTs displayed attractive device parameters: an electron mobility (μ) of 0.12 cm² V⁻¹ s⁻¹, a threshold voltage (V_th) of 22.20 V, and a five-orders-of-magnitude on/off ratio. This device was sensitive toward Cu²⁺ among 13 metal cations and toward CN⁻ among nine anions, as measured through changes in the values of V_th and I_off in the presence of Cu²⁺ cations and a change in the value of I_sat in the presence of CN⁻ anions. We observed selectivity toward both of these ions in mixed ion solutions, with sensitivity over different concentrations (from 20 to 350 μM for Cu²⁺; from 100 to 350 μM for CN⁻) as well as in sea water. The pyrene derivative self-assembled through pyrene–pyrene^* coordination in the presence of Cu²⁺ ions; the rods of the pyrene derivative broke into smaller pieces upon formation of benzoxazole rings in the presence of CN⁻ ions, as confirmed using atomic force microscopy and fourier transform attenuated total reflection spectroscopy.     

Superhydrophilic All-pH-Adaptable Redox Conjugated Porous Polymers as Universal and Ultrarobust Ion Hosts for Diverse Energy Storage with Chemical Self-Chargeability

Herein, a new fibrous conjugated microporous polymer bearing phenazine species (PNZ-CMP) is reported as a universal and ultrastable electrode to host various mono- and multi-valent charge carriers for diverse aqueous rechargeable cells combining rapid kinetics, ultralong lifespan, and chemical rechargeability. The porous cross-linked structure, interconnected donor-acceptor network, and readily accessible active sites endow PNZ-CMP with highly-reversible redox activity, superhydrophilicity, facile electron transport, high ion diffusion coefficient, and all-pH-adaptability (−1 to 15) in aqueous electrolytes. Thus, adopting PNZ-CMP electrodes enables good compatibility with H⁺/Li⁺/Na⁺/K⁺/Zn²⁺/Al³⁺ ions and fast surface-controlled redox reactions for diverse aqueous battery chemistry. Multiple PNZ-CMP-based full cells show superior electrochemical performance especially ultralong lifespan, e.g., ≈84% capacity retention over 200 days for K⁺, ≈100% over 127 days for Zn²⁺, and ≈76% over 47 days for anion-coordinated Al ions, surpassing small molecule counterparts and most previously-reported corresponding systems. The spontaneous redox chemistry of reduced phenazine species with O₂ is first explored to render PNZ-CMP with repeatable chemical self-chargeability in four electrolytes. Especially in 0.05 m H₂SO₄, an accumulative discharge capacity up to 48505 mAh g⁻¹ is achieved via facile self-charging, which can originate from the “reactive antiaromaticity to stable aromaticity” conversion of the redox moieties as revealed by theoretical studies.     

Synthesis and characterization of the semiconductor Li0.93Cu0.07Nb3O8: Application to oxygen evolution under visible light

The semiconductor Li_0.93Cu_0.07Nb₃O₈ is prepared by soft chemistry in aqueous electrolyte via Cu²⁺ → Li⁺ exchange between copper nitrate and LiNb₃O₈. The substituted niobate crystallizes in an orthorhombic symmetry and the semiconducting and photo-electrochemical properties are investigated for the first time. The oxide exhibits a dark brown color and the UV–Visible spectroscopy gives an optical gap of 1.42 eV, due to the crystal field splitting of Cu²⁺ in octahedral site. The thermal variation of the conductivity shows that Nb: 4d-electrons are localized and the data are fitted by a small-polaron hopping model σ = σ_o exp {−0.053 eV/kT} with a carrier density thermally activated. The capacitance measurement done in ionic electrolyte (Na₂SO₄, 10⁻² M) indicates n type semiconductor with mixed valences Nb^5+/4+, due to the hetero-valent substitution Li⁺/Cu²⁺, with a flat band potential of 0.28 V_SCE and electrons density of 2.17×10¹⁷ cm⁻³. The Nyquist diagram shows mainly the bulk contribution with a diffusion process. The valence band (6.39 eV below vacuum) derives from O^2-: 2p orbital with a small admixture of Cu²⁺: 3d character while the conduction band is made up of Nb⁵⁺: 4d orbital. The material is successfully tested for the oxygen generation with an evolution rate of 87 µmol mn⁻¹ g⁻¹ under visible light (29 mW cm⁻²) and a quantum yield of 0.35%.     

Tailoring Anion Association Strength Through Polycation-Anion Coordination Mechanism in Imidazole Polymeric Ionic Liquid-Based Artificial Interphase toward Durable Zn Metal Anodes

Artificial interface layer engineering is an efficacious modification strategy for protecting zinc anode from dendrite growth and byproducts formation. However, the high bulk ionic conductivity of most artificial interfacial layers is mainly contributed by the movement of anions (SO₄²⁻), which is the source of parasitic reactions on zinc anode. Herein, a high zinc ion donor transition (σZn²⁺ = 3.89 × 10⁻² S cm⁻¹) imidazole polymeric ionic liquid interface layer (1-carboxymethyl-3-vinylimidazolium bromide monomer, CVBr) for Zn metal protection is designed. The N⁺ atom of imidazole rings is connected by chains to form the cavities and the anions are confined within these cavities. Thus, the hindering effect of surrounding units on the anions leads to the subdiffusive regime, which inhibits the diffusion of SO₄²⁻ in interface and increases Zn²⁺ transference number. Besides, the polycation-anion coordination mechanism of PolyCVBr ensures accelerated Zn²⁺ transition and realizes rapid internal Zn²⁺ migration channel. As a result, the Zn@CVBr||AM symmetry cells deliver high bulk ionic conductivity (4.42 × 10⁻² S cm⁻¹) and high Zn²⁺ transference number (tZn²⁺ = 0.88) simultaneously. The Zn@CVBr||AM-NaV₃O₈ pouch cells display the capacity retention of 88.9% after 190 cycles under 90° bending, verifying their potential practical application.     

Synthesis and optoelectronic properties of a series of novel spirobifluorene derivatives starting from the readily available reagent 4,4′-bisalkylated biphenyl

Five novel spirobifluorene derivatives, SPF-DM, SPF-MB, SPF-BB, BSPF-NA1 and BSPF-NA2 were synthesized starting from the readily available reagent 4,4′-bisalkylated biphenyl. Their linear absorption, fluorescence and thermal properties were examined and their redox potential levels were estimated by cyclic voltammetry. These compounds possess high thermal stability. SPF-MB and SPF-BB possess excellent spectral sensitivities to pH changes and can be used as optical pH sensors of a wide pH range. The recognition behavior of SPF-BB toward various metal ions has been evaluated in a acetonitrile/water (15:1, v/v) solvent system. SPF-BB is highly selective in recognizing Ag⁺. The electroluminescent properties of SPF-DM, SPF-MB, BSPF-NA1 and BSPF-NA2 are demonstrated with a device configuration of ITO/MoO₃ (6 nm)/NPB (80 nm)/EML (30 nm)/TPBI (40 nm)/LiF (1 nm)/Al (100 nm). The devices of BSPF-NA1 and BSPF-NA2 display a yellow emission in the EL spectra and their maximum brightness reached 380 and 311 cd m^?2, respectively. At low turn-on voltage (7.9 V) a light blue emission was observed in the device of SPF-DM and its maximum brightness reached 391 cd m^?2. Notably, the device of SPF-MB has a white emission with CIE coordinates (0.293, 0.307).     

Single-Atom Metal Sites Anchored Hydrogen-Bonded Organic Frameworks for Superior “Two-In-One” Photocatalytic Reaction

Photoredox catalysis is a green solution for organics transformation and CO₂ conversion into valuable fuels, meeting the challenges of sustainable energy and environmental concerns. However, the regulation of single-atomic active sites in organic framework not only influences the photoredox performance, but also limits the understanding of the relationship for photocatalytic selective organic conversion with CO₂ valorization into one reaction system. As a prototype, different single-atomic metal (M) sites (M²⁺ = Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺) in hydrogen-bonded organic frameworks (M-HOF) backbone with bridging structure of metal-nitrogen are constructed by a typical “two-in-one” strategy for superior photocatalytic C N coupling reactions integrated with CO₂ valorization. Remarkably, Zn-HOF achieves 100% conversion of benzylamine oxidative coupling reactions, 91% selectivity of N-benzylidenebenzylamine and CO₂ conversion in one photoredox cycle. From X-ray absorption fine structure analysis and density functional theory calculations, the superior photocatalytic performance is attributed to synergic effect of atomically dispersed metal sites and HOF host, decreasing the reaction energy barriers, enhancing CO₂ adsorption and forming benzylcarbamic acid intermediate to promote the redox recycle. This work not only affords the rational design strategy of single-atom active sites in functional HOF, but also facilitates the fundamental insights upon the mechanism of versatile photoredox coupling reaction systems.     

Pulverizing Fe2O3 Nanoparticles for Developing Fe3C/N-Codoped Carbon Nanoboxes with Multiple Polysulfide Anchoring and Converting Activity in Li-S Batteries

Sluggish redox kinetics, shuttle effect, poor conductivity, and large volume change of sulfur limit the practical applications of lithium-sulfur batteries. Hollow, porous, and necklace-like Fe₃C/N-codoped carbon nanoboxes (Fe₃C/NC) connected by N-doped carbon (NC) nanofibers are designed by pulverizing Fe₂O₃ embedded in polyacrylonitrile (PAN) fibers to produce multifunctional sulfur hosts, which exhibit multiple polysulfide anchoring and catalytic conversion activities. Experimental and first-principles density functional theory studies reveal that the uniformly distributed Fe₃C and N units in the nanoboxes can significantly suppress the polysulfide shuttle effect. The conversion of polysulfides (LiPSs) to Li₂S is catalyzed during discharge. The process relies on the fast electron transfer through the NC nanofibers and facilitated Li⁺ diffusion through the porous nanobox shells. The structural characteristics (“boxes in fibers”) of the nanoboxes influence the high sulfur loading and tolerance of volume variation of LiPSs, resulting in the synergistic catalysis of the redox reactions. A high capacity of 645 mAh g⁻¹ after 240 cycles at 1 C, a high capacity of 712 mAh g⁻¹ at a high sulfur loading of 5 mg cm⁻² after 100 cycles at 0.2 C, and an enhanced areal capacity of 3.6 mAh cm⁻² are demonstrated.     

Harnessing Selectivity and Sensitivity in Ion Sensing via Supramolecular Recognition: A 3D Hybrid Gold Nanoparticle Network Chemiresistor

The monitoring of K⁺ in saliva, blood, urine, or sweat represents a future powerful alternative diagnostic tool to prevent various diseases. However, several K⁺ sensors are unable to meet the requirements for the development of point-of-care (POC) sensors. To tackle this grand-challenge, the fabrication of chemiresistors (CRs) based on 3D networks of Au nanoparticles covalently bridged by ad-hoc supramolecular receptors for K⁺, namely dithiomethylene dibenzo-18-crown-6 ether is reported here. A multi-technique characterization allows optimizing a new protocol for fabricating high-performing CRs for real-time monitoring of K⁺ in complex aqueous environments. The sensor shows exceptional figures of merit: i) linear sensitivity in the 10^–3 to 10^–6 m concentration range; ii) high selectivity to K⁺ in presence of interfering cations (Na⁺, Ca²⁺, and Mg²⁺); iii) high shelf-life stability ( > 45 days); iv) reversibility of K⁺ binding and release; v) successful device integration into microfluidic systems for real-time monitoring; vi) fast response and recovery times ( < 18 s), and v) K⁺ detection in artificial saliva. All these characteristics make the supramolecular CRs a potential tool for future applications as POC devices, especially for health monitoring where the determination of K⁺ in saliva is pivotal for the early diagnosis of diseases.     

Selective Zinc(II)‐Ion Fluorescence Sensing by a Functionalized Mesoporous Material Covalently Grafted with a Fluorescent Chromophore and Consequent Biological Applications

A highly ordered 2D‐hexagonal mesoporous silica material is functionalized with 3‐aminopropyltriethoxysilane. This organically modified mesoporous material is grafted with a dialdehyde fluorescent chromophore, 4‐methyl‐2,6‐diformyl phenol. Powder X‐ray diffraction, transmission electron microscopy, N₂ sorption, Fourier transform infrared spectroscopy, and UV‐visible absorption and emission have been employed to characterize the material. This material shows excellent selective Zn²⁺ sensing, which is due to the fluorophore moiety present at its surface. Fluorescence measurements reveal that the emission intensity of the Zn²⁺‐bound mesoporous material increases significantly upon addition of various concentrations of Zn²⁺, while the introduction of other biologically relevant (Ca²⁺, Mg²⁺, Na⁺, and K⁺) and environmentally hazardous transition‐metal ions results in either unchanged or weakened intensity. The enhancement of fluorescence is attributed to the strong covalent binding of Zn²⁺, evident from the large binding constant value (0.87 × 10⁴ M ^?1). Thus, this functionalized mesoporous material grafted with the fluorescent chromophore could monitor or recognize Zn²⁺ from a mixture of ions that contains Zn²⁺ even in trace amounts and can be considered as a selective fluorescent probe. We have examined the application of this mesoporous zinc(II) sensor to cultured living cells (A375 human melanoma and human cervical cancer cell, HeLa) by fluorescence microscopy.