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A new coordination polymer {[Zn2(ADDA)2(DMF)(H2O)2]·(DMF)}n (HPU-22) (H2ADDA = 4,4′-(anthracene-9,10-diyl) dibenzoic acid) based on an anthracene ligand is designed to obtain a stimulus-responsive material. The fluorescence color of HPU-22 changes under thermal stimuli. Single-crystal structural analysis demonstrates a slight alteration in the distance between adjacent anthracene rings, resulting in the changes in the fluorescence color. The changed fluorescence can be restored by simply wetting the product. The stimulus-responsive mechanism has also been explored in detail by using other characterization procedures. Results demonstrate that the emission properties are dependent on the arrangement of anthracene. This work contributes to the understanding of the thermochromic luminescence mechanism and the development of thermochromic luminescence materials with excellent performance. [ABSTRACT FROM AUTHOR]

In this paper, we report the synthesis of a multifunctional fluorescent probe Tb-CP, Tb(HL)(EtOH) 2 (NO 3) 2 (HPU-10) (H 2 L = 2,6-bis-(5-pyridin-4-yl-1H-[1,2,4]triazol-3-yl)- pyridine), and demonstrate that this novel chemosensor has the property of ratiometric detection of Zn2+ and Cd2+. The detection limit of HPU-10 sensing Zn2+ and Cd2+ is 0.319 and 0.965 μM, respectively. The sensing mechanism can be explained by (i) the decomposition of HPU-10 and (ii) the recombination of Zn2+ or Cd2+ with ligand forming 2HL--Zn2+ or 2HL--Cd2+, respectively. Moreover, the fluorescent sensor HPU-10 can detect the nitroaromatic compound 2, 4-DNP via a fluorescence quenching mechanism. The detection limits obtained from linear regression curve plots of 2, 4-DNP is calculated to be 1.69 μM. In addition, the possible use of the probe coated paper for tracing the target analytes has also been presented. A highly selective and sensitive multi-functional luminescent chemosensor Tb-CP for ratiometric detecting Cd2+ and Zn2+ and selective discrimination of 2, 4-DNP by fluorescence quenching was successfully obtained. Image 1 • HPU-10 displays ratiometric sensing of Zn2+ and Cd2+ by forming 2HL--Zn2+ and 2HL--Cd2+. • HPU-10 exhibited fluorescence quenching detection of 2, 4-DNP. • HPU-10 can be used as a multifunctional sensor for Zn2+, Cd2+ and 2, 4-DNP in practical. [ABSTRACT FROM AUTHOR]

A novel Cu NCs@Cu-MOF material with the combination of catalysis and fluorescence was synthesized by a new strategy, realizing the sensing of H 2 O 2 and 2,4-DNP. [Display omitted] • A multifunctional Cu NCs@Cu-MOF probe was synthesized by using Cu-MOF as template. • It could detect H 2 O 2 through fluorescent color changing from red to yellow. • 2,4-DNP detection was also achieved through fluorescence quenching. • The limits of detection (LOD) of H 2 O 2 and 2,4-DNP are 72.5 and 67 nM, respectively. • A portable sensor was fabricated for efficient sampling of microparticulates. Establishing a sensing system for detecting various kinds of explosives is of great significance due to the threats they pose to global security. In this work, a novel Cu NCs@Cu-MOF material with a good catalytic property and intense red emission (610 nm) was synthesized by using Cu-MOF as the template and 2,3,5,6-tetrafluorobenzenethiol (TFTP) as the redundant. Benefiting from this in situ strategy, the final product Cu NCs@Cu-MOF preserved the peroxidase-like properties of Cu-MOF, which could efficiently catalyze H 2 O 2 to produce ·OH and then oxidize o-Phenylenediamine (OPD) to its oxidation product (OxOPD) to generate a yellow emission at 560 nm. Furthermore, the strong red fluorescence of Cu NCs@Cu-MOF could be quenched quantitatively with the increase of the concentration of 2,4-dinitrophenol (2,4-DNP) due to the IFE effect. Consequently, with 560 and 610 nm as the response signals, the synthesized material could be employed as H 2 O 2 and 2,4-DNP sensor with the limits of detection (LOD) of 72.5 and 67 nM, respectively. In addition, owning to the difficulty of explosives sampling, a portable sensor was fabricated by using PVA hydrogel as a carrier to load the designed fluorescent material, realizing efficiently sampling of microparticulate from diverse substrates and the on-site sensing. [ABSTRACT FROM AUTHOR]

The development of high-performance sensors for rapidly detecting acetylacetone (AP) in water samples is necessary because its release into the environment can result in many vital problems for human health and environment. Herein, we first designed a hybrid by integrating HOF with ZIF-8 through a sequential growth strategy. By separately introducing blue-emitting SiQDs and green- and red-emitting Tb3+ and Eu3+ into ZIF-8 and HOF, the resultant ZIF-8@SiQDs@HOF@Eu3+@Tb3+ comprised three emission peaks at 484, 545 and 620 nm, all of which could be employed as switch-off responsive peaks to low concentrations of AP with a detection limit of 0.79 ppm. However, in environments with high concentrations of AP, a turn-on signal at 484 nm was observed. Thereupon, the ratiometric fluorescence intensity of the ternary emission varied within different concentration ranges, accompanied by the fluorescence color evolution from red to salmon to plum to purple to final blue. Moreover, a portable sensing film was fabricated for rapid warning, sensitive and visual determination of AP in complicated environments. Therefore, this triple-emission sensor with wide color variations and strong anti-interference advantages could promote further research to improve the selectivity, sensitivity and inherent self-correction of multimodal fluorescence detection and the ease of sensing operation. A triple-emission sensor ZIF-8@SiQDs@HOF@Eu3+@Tb3+ could recognize a low concentration of AP with turn-off signal and a high concentration of AP with turn-on fluorescence. [Display omitted] • A triple-emission ZIF-8@SiQDs@HOF@Eu3+@Tb3+ sensor for AP was synthesized. • The detection limit of AP was 0.79 ppm. • The sensor could recognize different concentrations of AP through different signals. • The fluorescence color emerged from red to salmon, plum to purple to final blue. • A portable sensing film was fabricated for fast detection of AP. [ABSTRACT FROM AUTHOR]

A palygorskite (Pal)-based ratiometric fluorescent nanoprobe is designed in order to establish a real time, on-site visual, and highly sensitive detection method for tetracyclines (TCs). The nanoprobe comprises the green emissive dye molecules embedded in the natural Pal, which serve as the internal reference signal. The potential red-emissive seed-europium (Eu 3+ ) ions are covalently bound on the surface of modified Pal, and they can act as the specific recognition element. The emission intensity of Eu 3+ ions significantly increases upon TC addition. The nanoprobe fluorescence changes from green to yellow, orange, or red, thereby accomplishing the visual ratiometric fluorescent detection. This nanoprobe exhibits a high sensitivity with a detection limit of 7.1 nM and an excellent selectivity in monitoring the levels of TCs in milk samples. In addition, this nanoprobe is useful for quantitative determination of TCs, and it is not affected with intensity fluctuations due to instrumental or environmental factors. The nanoprobe-immobilized test paper realizes real-time TCs analysis by using a smartphone with an easy-to-access color-scanning APP as the detection platform. Moreover, the reported construction of visual ratiometric detection system follows the sustainable development idea, that is, from nature, for nature, and into the nature. [ABSTRACT FROM AUTHOR]

Since the 2001 anthrax attacks, researchers have focused on the development of a bacterial spore biomarker detector with rapid response time and high sensitivity and selectivity. Hence, a ratiometric fluorescent nanosensor based on lanthanide-functionalized attapulgite (Atta) was designed and prepared using dye-doped Atta as an internal reference. Atta, which is famous because of Maya Blue, is a hydrated magnesium aluminum silicate present in nature, with pronounced adsorption and a large specific surface area rich in silicon hydroxyl. The adsorption of dye molecules benefits the formation of an internal reference with orange fluorescence. Meanwhile, silicon hydroxyl would be available for terbium (Tb 3+ ) complex grafting, which favors the sensitization of the bacterial spore biomarker. With increasing dipicolinic acid (DPA) concentrations, energy transfer from DPA to Tb 3+ gradually enhanced, thereby resulting in strong and predominant green fluorescence. The ratiometric fluorescence intensity is highly sensitive. It has a limit of detection of 9.8 nM, which is much lower than the infectious dosage of Bacillus anthracis spores (60 μM) for humans. The rapid response time (10s), high selectivity, and reliable and practical performances in actual applications make this ratiometric fluorescent nanosensor useful in the detection of biomarkers for various bacterial spores. Moreover, the reported construction of visual ratiometric detection system follows the sustainable development idea of ‘‘from nature, for nature, into the nature’’ and promotes the use of naturally renewable resources to produce promising and eco-friendly functional materials for various applications. [ABSTRACT FROM AUTHOR]

Bioluminescent calcium fluorapatite nanocrystals (TCaFAp:Eu) with controlled morphology were fabricated through an easy one-step method and found to have excellent water dispersibility and biocompatibility. Further modification of conjugation with both optical imaging and cell targeting capabilities provided useful nanoprobes for highly sensitive biorecognition applications, which was realized by grafting folic acid onto the surface of TCaFAp:Eu. The uptake of designed TCaFAp:Eu-FA by HepG2 cancer cells was verified by confocal laser scanning microscopy after 30 min, whereas the uptake of TCaFAp:Eu-FA by MCF-7 cells did not work, indicating that the prepared nanoprobe effectively targeted the imaging of cancer cells with over-expression of folate receptor. [ABSTRACT FROM AUTHOR]

Developing multifunctional luminescent switches for detecting various poisons are urgent given the continuous deterioration of the environment. Herein, a new porous fluorescent metal–organic framework [Tb 2 (TPTC)(DMA) 4 (NO 3) 2 ] n (HPU-25) was initially designed. Then, fluorophore molecule tris(2,2′-bipyridine) dichlororuthenium(II) hexahydrate (Ru(bpy) 3 2+) was loaded onto HPU-25 by a simple post-synthesis strategy to prepare a new ratio fluorescence sensor Ru(II)@HPU-25. As a sensor, it can detect 2,6-pyridinedicarboxylic acid (DPA) content in real-time, with high sensitivity and selectivity, without being disturbed by probe concentration and environment. Evident changes in fluorescence color and intensity are observed in distinguishing DPA contents. In addition, after detecting DPA, it can be used for consecutive visual detection of dichromate anion (Cr 2 O 7 2−) in water. This multifunctional fluorescence sensor could make up for the defects of single fluorescence and single function of the traditional fluorescence sensor by using the dual strategies of ratio sensing and cascade sensing. Interestingly, DPA and Cr 2 O 7 2− in samples can be visually detected rapidly in real-time through the chroma acquisition APP on smartphone. More importantly, we also designed the combination of two logic gate operations for sensing the two targets. In the poison detection in daily life, these intelligent applications of fluorescence sensors have a broad development space. [Display omitted] • A novel multifunctional fluorescent sensor Ru(II)@HPU-25 is designed. • The dual strategy of ratio sensing and cascade sensing are used to design the sensor. • The quantitative continuous detection of DPA and Cr 2 O 7 2− was realized by changing the independent fluorescence signals. • The logic gate circuits of fluorescence sensors are designed. [ABSTRACT FROM AUTHOR]