Query: visual detection using metallic-organic framework for ratiometric

title: Ratiometric and Turn On Luminescence Detection of Water in Organic Solvents Using a Responsive Europium Organic Framework.
abstract: The development of simple, rapid response sensors for water detection in organic solvents is highly desirable in the chemical industry. Here we demonstrate a unique luminescence water sensor based on a dual emitting europium organic framework (Eu MOF) which is assembled from a purposely selected 2 aminoterephthalic acid ligand with responsive fluorescence inherent in its intramolecular charge transfer (ICT) process. This ICT process can be rapidly switched on in the presence of water owing to its ability to boost and stabilize the ICT state. In contrast, the Eu3+ emission within the framework is insensitive to water and can serve as a reference, thus enabling highly sensitive water detection in a turn on and ratiometric way. In addition, the significant ratiometric luminescence response induced by water makes Eu MOF undergo a distinct change of emitting color from red to blue, which is favorable for visual analysis with the naked eye. Sensitive determination of water content (0.05 10% v/v) in various organic solvents is achieved in multiple readouts including ratiometric emission intensity, emission color, or the Commission Internationale de l'Eclairage (CIE) chromaticity coordinate. The present Eu MOF sensor featuring high sensitivity and reusability, self calibration, simple fabrication and operation, and capability for real time and in situ detection is expected to have practical applications in water analysis for industrial processes.

title: Double Color Lanthanide Metal Organic Framework Based Logic Device and Visual Ratiometric Fluorescence Water Microsensor for Solid Pharmaceuticals.
abstract: Water is one of the most widespread impurities and contaminants for pharmaceuticals and chemical products. A simple, fast and reliable water assay method is of high significance for pharmaceutical and chemical manufacturing industry. In this work, lanthanide metal organic framework Eu dipicolinic acid/2 aminophthalic acid (Eu DPA/PTA NH2) was prepared as a double color ratiometric fluorescent water sensor, which shows ultra sensitive (limit of detection 0.01% v/v) and linear broad range (0 100% v/v) response to water. An innovative analytical device based on one to two logic gate was constructed by using the water content and the two fluorescence responses as the input and output signals, respectively. The direct analysis of water content can be achieved by the four output types, NOT (0, 1) PASS 0 (0, 0) PASS 1 (1, 1) and YES (1, 0) Importantly, the MOF loaded fiber paper was prepared as a microsensor, and a water assay tube was designed for rapid water detection of solid pharmaceuticals via ratiometric chromaticity, coupled with a portable visual determination device. The paper based microsensor is response rapid (20 s) long term stable (at least 30 days) and can achieve the accurate (relative error 9.8% visual assay of trace water in solid pharmaceuticals. To our knowledge, this is the first time to report a MOF based double color ratiometric fluorescent water sensor, a water analytical logic device and a paper based water microsensor for point of care visual water assay in solid samples via ratiometric chromaticity.

title: A Ratiometric Fluorescent Nano Probe for Rapid and Specific Detection of Tetracycline Residues Based on a Dye Doped Functionalized Nanoscaled Metal Organic Framework
abstract: Tetracycline (TC) residues are harmful to the environment and human body, so it is necessary to develop a highly sensitive probe for rapid detection of tetracycline residues. In the present paper, a novel dye doped porous metal organic framework (UiO 66) based multi color fluorescent nano probe was designed for sensitive ratiometric detection of tetracycline (TC) In this probe, dye molecules doped UiO 66 was used as a fluorescent internal standard, and the externally grafted lanthanide Eu3+ complex was used as response signals. The fluorescence of the Eu3+ complex was selectively enhanced with increasing concentrations of TC, which was accompanied by a visual blue to red color switch. The nano probe had a linear response between 0.1 and 6 mM with a lowest detection limit of 17.9 nM, which was much lower than the maximum residue limits set by the United States Food and Drug Administration (676 nM) and the European Union (225 nM) The applicability of this method in the analysis of actual samples was evaluated by the determination of TC in honey and milk samples, indicating satisfactory recovery and good reproducibility. In addition, a cost effective paper based probe for rapid and visual detection of TC was developed by fixing the nano probe on filter papers. With the help of a smartphone camera to capture the fluorescence color, and chromaticity analysis software, the calculation and analysis of red (R) and blue (B) values can be realized, which has the potential for real time visual detection of TC.

title: Visual Detection of Fluoride Anions Using Mixed Lanthanide Metal Organic Frameworks with a Smartphone.
abstract: Fluoride ion (F is one of the most harmful elements in drinking water. Over intake of F can result in dental fluorosis, kidney failure, or DNA damage. Therefore, developing affordable, equipment free and reliable methods for F detection is an important goal. In this work, a series of mixed lanthanide metal organic frameworks were synthesized using a triazine based planar ligand, 4,4',4' s triazine 2,4,6 triyltribenzoate (TATB) and mixed lanthanide ions (Tb3+ and Eu3+ The luminescent color of the Tb/Eu(TATB) can be finely modulated by changing the Tb3+/Eu3+ ratio in the synthesis procedure. Benefiting from the unique host guest interaction (e.g. Lewis acid base interaction) between F and MOF host, a highly selective, sensitive, and reliable fluoride sensor was then developed. Moreover, visual detection of F was achieved with a smartphone by identifying the RGB value. Drinking water samples were analyzed for F and the results obtained by our ratiometric luminescent method were con sistent with those by ion chromatographic strategy. This easy to use sensor provides reliable detection of F in everyday appli cations for non expert users, especially in remote rural areas.

title: On site, rapid and visual determination of Hg2+ and Cu2+ in red wine by ratiometric fluorescence sensor of metal organic frameworks and CdTe QDs.
abstract: A ratiometric sensor of MOF/ CdTe QDs was constructed by physically mixing CdTe QDs (lem 605 nm) with MOF (Fe MIL 88NH2,lem 425 nm) Under an UV lamp (lex 365 nm) orange red CdTe QDs is gradually quenched with increasing levels of Hg2+ or Cu2+ while blue MOF is unchanged, accompanying with a visual change from bright pink to blue fluorescence. Hence, a new method for determining Hg2+ and Cu2+ by MOF/CdTe QDs sensor is established, whose detection limits are 0.22 ng mL 1 for Hg2+ (2.1% RSD) and 0.26 ng mL 1 for Cu2+ (1.1% RSD) respectively. In addition, on site, rapid and visual determination of Hg2+/Cu2+ in red wine without any pretreatment is realized by using a MOF/CdTe QDs paper based sensor. For Hg2+ and Cu2+ the semi quantitative detection ranges of the paper based sensor are both 10 5000 ng mL 1, implying that it has great application value in analyzing Hg2+ and Cu2+ in liquid samples.

title: Dual functional lanthanide metal organic frameworks for visual and ultrasensitive ratiometric fluorescent detection of phosphate based on aggregation induced energy transfer.
abstract: Phosphate (Pi) not only plays a significant role in physiological processes, but also is an important indicator for aquatic ecosystems. The dual functional lanthanide metal organic frameworks (MOFs) were synthesized for visual and ultrasensitive ratiometric fluorescent detection of Pi based on aggregation induced energy transfer. In the MOFs material, ciprofloxacin (CIP) functions as an energy donor and results in the fluorescence enhancement of Eu3+ the introduction of pyromellitic acid can cause the aggregation of the CIP Eu3+ complex, and red characteristic fluorescence of Eu3+ at 614 nm is further enhanced (about 40 times) When Pi is added to the MOFs solution, CIP is released from the MOFs, red fluorescence of Eu3+ is quenched and blue fluorescence of CIP is simultaneously recovered, thereby a ratiometric fluorescent probe for the detection of Pi was fabricated. The fluorescent response based on intermolecular energy transfer of the CIP Eu3+ complex is very sensitive to Pi. The limit of detection (3s/K) of the probe is ultrasensitive and attains 4.4 nM. The possible interferential substances such as 17 common metal ions and 14 anions investigated do not interfere with the Pi detection. The ratiometric fluorescent probe has been successfully used in the determination of Pi in real human urine and lake water samples. This work may supply a new strategy for fabricating ratiometric fluorescent probe and a prospective application in biological and environmental samples.

title: Assembly of black phosphorus quantum dots doped MOF and silver nanoclusters as a versatile enzyme catalyzed biosensor for solution, flexible substrate and latent fingerprint visual detection of baicalin.
abstract: In this work, a versatile enzyme catalyzed biosensor was developed by using the assembled nanohybrids of black phosphorus quantum dots (BPQDs) doped metal organic frameworks (MOF) and silver nanoclusters (AgNCs) The nanohybrids of AgNCs/BPQDs/MOF exhibit dual emissive fluorescence (FL) centers at 630 nm (red) and 535 nm (blue) under excitation at 440 nm. Baicalin enhances the activity of catalase and catalytic decomposition of H2O2. With increase of baicalin contents in the mixture containing nanohybrids, catalase and H2O2, the catalase caused decomposition of H2O2 was accelerated and the excessive H2O2 was consumed. Baicalin can restrain the oxidation capability of H2O2. The red FL (response signal) of AgNCs adhering to MOF increases, while blue FL (reference signal) of BPQDs doped into MOF has negligible changes. A new ratiometric FL biosensor was designed based on nanohybrids and enzyme catalyzed reaction. This biosensor enables the detection of baicalin in the range of 0.01 500 mg mL 1, with a limit of detection of 3 ng mL 1. This biosensor has high sensitivity, selectivity and stability for baicalin detection in practical samples. Especially, it performed the solution, flexible substrate and latent fingerprint visual detection of baicalin through direct observation of FL color shades with naked eyes. This work explored a facile and efficient semi quantitative method for versatile FL visual detection, which can promote the development of advanced chemo/bio sensors and analysis methods.

title: Metal Organic Framework as a Chemosensor Based on Luminescence Properties for Monitoring Cetyltrimethylammonium Bromide and Its Application in Smartphones.
abstract: Rapid and sensitive detection of surfactants has attracted more and more attention since surfactants not only cause water pollution but also affect the health of human beings. Luminescent metal organic frameworks combining unique optical property and inherent permanent porosity for guest host encapsulation are widely used in fluorescence detection. Here we report a ratiometric fluorescent probe (denoted as UiO 66 NH2@PB) based on a Zr based metal organic framework (UiO 66 NH2) and a fluorescent dye, phloxine B (PB) for visual and fluorescent determination of cationic surfactants (cetyltrimethylammonium bromide; CTAB) The intensity ratio of dual emission sensor exhibits a linear response to the CTAB concentrations of 0.1 17 mM and obtains a low detection limit (0.074 mM) Moreover, this method has been successfully utilized to monitor CTAB in the environmental water samples with satisfied recoveries. Importantly, this work provides a new insight into developing smartphone based sensor to realize a rapid, on site visual and quantification based detection of CTAB.

title: Smartphone based ratiometric fluorescent definable system for phosphate by merged metal organic frameworks.
abstract: Phosphate plays an important role in a wide range of chemical and biological processes, so the development of a new phosphate optical sensor with high sensitivity, specificity and visual recognition function has important practical significance. Herein, a ratiometric fluorescent (RF) probe and a smartphone integrated colorimetric test paper sensing platform for assay phosphate was fabricated using hybrid fluorescent UiO 66 NH2 and Eu3+@MOF 808 metal organic frameworks. After continuous addition of phosphate, the blue fluorescence emission of UiO 66 NH2 and the red emission of Eu3+@MOF 808 were regularly enhanced and quenched respectively, and the fluorescence response of the detection platform to phosphate exhibited a clear color change process (red pink blue) More importantly, the probe solution and test paper of the integrated smartphone are converted to digital values through RGB channels and successfully used to visualize semi quantitative recognition of phosphate. In addition, an RF probe and a smartphone integrated fluorescent test paper were developed separately to devise logic gate devices for detecting phosphate. The multifunctional ratio sensing platform integrated by the smartphone furnishes a new strategy and broad prospects for the intelligent online identification of important targets in biological samples and environmental samples.

title: Luminescent Transparent Wood Based on Lignin derived Carbon Dots as a Building Material for Dual channel, Real time and Visual Detection of Formaldehyde Gas.
abstract: Formaldehyde (FA) is a widespread indoor air pollutant, and its efficient detection is a large industrial challenge. The development of a building material with real time and visual self detection of FA gas is highly desirable for meeting both construction and human health demands. Herein, a luminescent transparent wood (LTW) as the building material was developed for dual channel, real time, and visual detection of FA gas. It was fabricated by encapsulating multicolor lignin derived carbon dots (CDs) and poly (vinyl alcohol) (PVA) into a delignified wood framework. It exhibited 85% optical transmittance, tunable room temperature phosphorescence (RTP) and ratiometric fluorescence (FL) emission. The tunable luminescence was attributed to different CD graphitization and surface functionalization. The color responsive ratiometric FL and delayed RTP detections of FA were displayed over the range 20 1500 mM (R2=0.966, LOD=1.08 nM) and 20 2000 mM (R2=0.977, LOD=45.8 nM) respectively. The LTW was also used as an encapsulation film on a UV emitting InGaN chip to form white light emitting diodes, indicating the feasibility as a FA responsive planar light source. The operational notion of functional LTW can expand its applications to new fields such as stimuli responsive light transmitting window or planar light sources, while monitoring indoor air pollutants, temperature and humidity.