Disinfection byproducts (DBPs), as an emerging water pollutant, present increasing concern and risk in public health and water safety. Due to their low concentration levels and inherent similarity in molecular structures, sensitive and accurate determination of DBPs is still a challenge especially for onsite or online detection. Herein, a self-regulated fluorescent probe based on the Ag nanoprism-modified lanthanide metal-organic framework (AgNPR@EuMOF) is designed for trichloroacetic acid (TCAA) detection. The EuMOF is constructed with Eu as the metal node and 5-boronoisophthalic acid as the ligand. By introducing sulfhydryl groups into EuMOF, AgNPR can be anchored on the EuMOF surface through Ag-S bonds, enabling the synthesis of stable AgNPR@EuMOF composites. During the sensing process, the triangle AgNPR will react with the organic halogen molecule, accomplished with the blue shift of surface plasmon resonance absorption peak and the significant change in the fluorescence of EuMOF. This probe can detect TCAA in a wide concentration range (0.1-40 μM) with high sensitivity and specificity. The density functional theory calculation on binding energies between DBPs and AgNPR suggests that TCAA has the largest interaction ability with AgNPR than other DBPs. Moreover, the detection of TCAA in real tap water and swimming pool water is also demonstrated with high accuracy. The reported AgNPR@EuMOF represents one of the pioneer fluorescence probes in DBP detection, which holds great promise for onsite or online analysis of trace DBPs in water.

Nonconjugated and nonaromatic luminophores based on clustering-triggered emission derived from through-space conjugation have drawn emerging attention in recent years. The reported nonconventional luminophores are emissive in concentrated solution and/or in the solid state, but they tend to be nonluminescent in dilute solution, which greatly limits their sensing and imaging applications. Herein, we design unique clusteroluminogens through modification of cyclodextrin (CD) with amino acids to enable the intermolecular and intramolecular clusterization of chromophores in CD-based confined space. The resulted through-space interactions along with conformation rigidification originated from hydrogen bond interaction and complexation interaction generate blue to cyan fluorescence even in the dilute solution (0.035 wt.%, quantum yield of 40.70%). Moreover, the prepared histidine-modified CD (CDHis) is demonstrated for fluorescent detection of chlortetracycline with high sensitivity and selectivity. This work provides a new and universal strategy to synthesize nonconventional luminophores with bright fluorescence in dilute aqueous solution through molecular-level enhanced clusterization-triggered emission.

Color-coding analysis from chemicals of concern is in great demand, but faces low sensitivity and specificity, low resolution, and complex processing among the many challenges. Here, this work resolves these issues to enable the elusive quantitative detection of a variety of fluoroquinolone (FQ) antibiotics. A fluorescent sensor based on the dual-emitting lanthanide metal-organic frameworks combining Tb3+ and Eu3+ as the luminescent center and 1,3,5-benzenetricarboxylic acid as the ligand is constructed. Due to the different sensitization effects to lanthanide metals and different inherent fluorescence emissions of FQs, the sensor exhibits characteristic color variations towards nine FQ and enables the discriminative detection of multiple antibiotics with self-calibrated signals. For the first time, a polynomial surface fitting process is developed to correlate the coordinates of color-coding map and target concentration for quantitative analysis. Moreover, a smartphone-enabled sensing system is demonstrated for on-site imaging analysis of antibiotics. The demonstrated innovative antibiotic detection and color-coding-based signal processing approach will inform the development of cutting-edge analysis systems for public health and environmental monitoring.

Polyoxometalate (POM) clusters containing lanthanide ion (LnPOM) possess excellent luminescence features, but the envisaged applications are hindered by the challenges in integration into functional architectures. Herein, a novel cross‐linked cyclodextrin (CL‐CD) and LnPOM composite is developed and applied for discriminative detection of inorganic and organic phosphate phases. For inorganic phosphates, a ratiometric fluorescence response is demonstrated with excellent selectivity, and anti‐interference ability in complex analyte mixtures. The outstanding performance is attributed to the high affinity of POM and distinct interactions between La 3+ and Eu 3+ with the phosphate. For organophosphates, a “signal‐off” fluorescence response for p ‐nitrophenyl‐substituted organophosphates is discovered due to the encapsulation of nitrophenyl group into the hydrophobic cavity of CD that enhances the interactions between POM and p ‐nitrophenyl phosphate. The discriminative responses of CL‐CD–LnPOM to inorganic phosphates and organophosphates bring new insights into POM‐based fluorescence probes for the detection of inorganic and organic phases based on the intrinsic structural difference between the phosphate analogs.

A facile strategy to design graphitic carbon-encapsulated NiCo core-shell nanocomposites (NiCo@g-C) is achieved by a simple co-electrolysis process involving CO2 reduction. Carbon derived from the captured CO2 is uniformly deposited on the surface of as-prepared NiCo particle to form homogeneous coatings at a suitable processing condition. It is very interesting to reveal that the carbon coatings are in graphitic structures with an average thickness of similar to 70 nm due to the in-situ catalytic graphitization effect of reduced transition metal (Ni, Co). More interestingly, it is found that the as-formed graphite coatings can effectively inhibit the sintering between NiCo nucleis under a high operating temperature, resulting in the smaller particle size of NiCo@g-C than that of the obtained NiCo alloys without carbon coatings. Owing to the novel nanostructures, the NiCo@g-C shows excellent magnetic properties and enhanced hydrogen evolution reaction activity in comparison with bare NiCo alloys. This work gives a new clue to designing functional carbon-encapsulated metal/alloy composites with unique nanostructures at a relatively mild condition.