Luminescent Lanthanide Metal-organic Framework Research Articles

A fluorescent terbium-metal-organic framework material for high-sensitivity detection of vomitoxin and oxytetracycline hydrochloride in water.

A unique luminescent lanthanide metal-organic framework (LnMOF)-based fluorescence detection platform was utilized to achieve sensitive detection of vomitoxin (VT) and oxytetracycline hydrochloride (OTC-HCL) without the use of antibodies or biomolecular modifications. The sensor had a fluorescence quenching constant of 9.74 × 106 M-1 and a low detection limit of 0.68 nM for vomitoxin. Notably, this is the first example of a Tb-MOF sensor for fluorescence detection of vomitoxin. We further investigated its response to two mycotoxins, aflatoxin B1 and ochratoxin A, and found that their Stern-Volmer fluorescence quenching constants were lower than those of VT. In addition, the fluorescence sensor realized sensitive detection of OTC-HCL with a detection limit of 0.039 μM. In conclusion, the method has great potential as a sensitive and simple technique to detect VT and OTC-HCL in water.

Selective and Rapid Detection of 4-Nitrophenol in River and Treated Industrial Wastewater by a Luminescent Lanthanide Metal-Organic Framework Sensor.

Phenolic organic compounds are widely used industrial chemicals that exist extensively in the environment and have a significant impact on human health. 4-Nitrophenol (4-NP) is a typical phenolic organic compound found in aqueous environments. Efficient detection of 4-NP in wastewater is highly challenging due to the complexity of testing environmental samples. Herein, a luminescent lanthanide metal-organic framework (MOF) sensor based on the Eu3+ ion {[Eu(HL)(L)(H2O)]·2H2O}n (EuMOF; H2L = 5-(4H-1,2,4-triazol-4-yl)benzene-1,3-dicarboxylic acid) was successfully synthesized for efficient 4-NP detection in wastewater. Fluorescence sensing experiments revealed that 4-NP could greatly quench the EuMOF fluorescence. Subsequently, EuMOF was applied to 4-NP detection in distilled water, tap water, river water, and treated industrial wastewater, exhibiting high sensitivity, a fast response within 30 s, high selectivity, excellent reusability, and a low detection limit. Finally, the fluorescence quenching mechanism was explored and attributed to competitive absorption of irradiated light between 4-NP and the ligand.

AIE Ligand-Based Luminescent Ln-MOFs for Rapid and Selective Sensing of Tetracycline.

The design of highly stable and dual-emission lanthanide metal-organic frameworks (Ln-MOFs) is promising for practical chemical sensor applications. Rational design and synthesis of photoresponsive organic ligands provide a feasible approach to achieving highly fluorescent dual-emission Ln-MOFs. In this study, a tetraphenylpyrazine-based AIE ligand, H4L, was synthesized and combined with lanthanide ions (including Sm3+, Eu3+, Gd3+, and Tb3+) to fabricate a series of Ln-MOFs named Ln-L. The single-crystal analysis revealed that all Ln-L belonged to the tetragonal space group P4212 and featured a 2-fold interpenetrated 3D structure. Leveraging rational design, Eu-L exhibited a sensitive response to tetracycline, making it a promising fluorescence sensor for tetracycline detection. The experiments demonstrated that Eu-L could rapidly and quantitatively detect tetracycline and its analogs within 30 s. The lowest detection limits for tetracycline, oxytetracycline, and chlortetracycline were 0.43, 0.92, and 0.81 μM, respectively. Additionally, the probe displayed excellent reusability and exceptional selectivity. A plausible sensing mechanism was proposed, supported by both experimental and theoretical analyses. Furthermore, the study discovered that on-site and real-time determination of TCs in aqueous solutions could be achieved by using luminescence test papers and composite films derived from Eu-L.

Highly Luminescent Lanthanide Metal-Organic Frameworks with Tunable Color for Nanomolar Detection of Iron(III), Ofloxacin and Gossypol and Anti-counterfeiting Applications.

Solvothermal reaction of 5,5'-(pyridine-2,6-diylbis(oxy))diisophthalic acid (H4 L) with europium(III) or terbium(III) nitrates in acetonitrile-water (1 : 1) at 120 °C gave rise to isostructural 2D coordination polymers, [Ln(HL)(H2 O)3 ]∞ (NIIC-1-Eu and NIIC-1-Tb), the layers of which are composed by eight-coordinated lanthanide(III) ions interconnected by triply deprotonated ligands HL3- . The layers are packed in the crystal without any specific intermolecular interactions between them, allowing the facile preparation of stable water suspensions, in which NIIC-1-Tb exhibited top-performing sensing properties through luminescence quenching effect with exceptionally low detection limits towards Fe3+ (LOD 8.62 nM), ofloxacin (OFX) antibiotic (LOD 3.91 nM) and cotton phytotoxicant gossypol (LOD 2.27 nM). In addition to low detection limit and high selectivity, NIIC-1-Tb features fast sensing response (within 60-90 seconds), making it superior to other MOF-based sensors for metal cations and organic toxicants. The photoluminescence quantum yield of NIIC-1-Tb was 93 %, one of the highest among lanthanide MOFs. Mixed-metal coordination polymers NIIC-1-Eux Tb1-x demonstrated efficient photoluminescence, the color of which could be modulated by the excitation wavelength and time delay for emission monitoring (within 1 millisecond). Furthermore, an original 2D QR-coding scheme was designed for anti-counterfeiting labeling of goods based on unique and tunable emission spectra of NIIC-1-Ln coordination polymers.

Fabrication of the Antibiotic Sensor by the Multifunctional Stable Adjustable Luminescent Lanthanide Metal–Organic Frameworks

In recent years, the irrational use of antibiotics has become very widespread. It is necessary to regulate this phenomenon through antibiotic detection. In this work, a series of isomorphic Ln-MOFs (Ln = Tb3+ and Eu3+) were synthesized from 1,3,5-tri(4-carboxyphenyl)benzene (H3L) and Ln3+ by the solvothermal method for the first time. A series of 1-EuxTb1-x with different luminescence were doped by changing the molar ratio of Tb3+ and Eu3+. Ln3+ forms a 4-connected 2D network structure through self-assembly with fully deprotonated L3-. It shows good chemical stability in water, and its luminescence is not affected by aqueous solutions with different pH values. 1-Eu demonstrates rapid and sensitive detection capabilities for MDZ and TET with good recyclability and low detection limits (10-5). In order to increase the practicability of 1-Eu, two portable sensors have been prepared, in which the fluorescent film (Film@1-Eu) has a detection limit of 10-4, and the sensitivity is only less than 10% of the titration results. A portable fluorescent test paper can reach the detection limit of 14.7 ppm. This study provides a new idea for the application of stable multifunctional materials in the field of fluorescence sensing.

Boosting the optical properties of polylactic acid/ lanthanide-based metal-organic framework composites

Luminescent lanthanide metal-organic frameworks (LnMOF) are gathering much interest in the scientific community due to their exceptional optical properties, which have the potential to revolutionize several application fields, including anti-counterfeiting. The traceability of the original products is an ever-growing demand for producers and end-users to verify the authenticity of produced goods. Following this newfound need, we propose an anti-counterfeiting method based on a quick-response (QR) code, with a very specific verification procedure, using a luminescent LnMOF-based composite. The embedded code will only react to certain stimulation, hence it can only be unlocked using the sequence that is programmed to respond to. For that purpose, we explored the incorporation of fresh LnMOFs, with europium (EuMOF) and terbium (TbMOF), on a biodegradable polymer matrix of polylactic acid (PLA). A homogeneous mixture of PLA/LnMOF was produced via a two-step process including solvent casting followed by thermal mixing, after achieving the optimized concentration for each filler. The optical characterization of the fresh composites showed an excellent response to selective excitation, with well-defined intraionic lines for TbMOF @ 542 nm (5D4→7F5) and for EuMOF @ 615 nm (5D0→7F2). PLA/Eu, TbMOF composites were also explored to create an additional level of encryption by tuning the emitted color with the appropriate excitation stimuli. Hence, these new luminescent composite materials can be used as traceable optical tags for a wide variety of polymeric products, capable to respond to a very specific excitation wavelength and act as a level three luminescent security marker, whose decoding demands the assessment of more than one factor, with near-impossible replication. Additionally, this technology has a high potential for scalability since the applied processing techniques used for the production of the optically active QR code are commonly employed in the polymer industry. Nevertheless, the analysis of the aged effects clearly indicates the need for a definition of new strategies to enhance the efficiency of the sensitization process of the Ln3+ intraionic emission.

Water-Stable Carborane-Based Eu3+/Tb3+ Metal-Organic Frameworks for Tunable Time-Dependent Emission Color and Their Application in Anticounterfeiting Bar-Coding.

Luminescent lanthanide metal–organic frameworks (Ln-MOFs) have been shown to exhibit relevant optical properties of interest for practical applications, though their implementation still remains a challenge. To be suitable for practical applications, Ln-MOFs must be not only water stable but also printable, easy to prepare, and produced in high yields. Herein, we design and synthesize a series of mCB-EuyTb1–y (y = 0–1) MOFs using a highly hydrophobic ligand mCBL1: 1,7-di(4-carboxyphenyl)-1,7-dicarba-closo-dodecaborane. The new materials are stable in water and at high temperature. Tunable emission from green to red, energy transfer (ET) from Tb3+ to Eu3+, and time-dependent emission of the series of mixed-metal mCB-EuyTb1–y MOFs are reported. An outstanding increase in the quantum yield (QY) of 239% of mCB-Eu (20.5%) in the mixed mCB-Eu0.1Tb0.9 (69.2%) is achieved, along with an increased and tunable lifetime luminescence (from about 0.5 to 10 000 μs), all of these promoted by a highly effective ET process. The observed time-dependent emission (and color), in addition to the high QY, provides a simple method for designing high-security anticounterfeiting materials. We report a convenient method to prepare mixed-metal Eu/Tb coordination polymers (CPs) that are printable from water inks for potential applications, among which anticounterfeiting and bar-coding have been selected as a proof-of-concept.

A selective dual-response biosensor for tyrosinase monophenolase activity based on lanthanide metal-organic frameworks assisted boric acid-levodopa polymer dots

Tyrosinase (TYR) monophenolase activity plays a key role in the development of diseases such as melanoma. The selective and sensitive detection of TYR monophenolase activity is a persistent challenge. Here, by integrating fluorescent polymer dots and a luminescent lanthanide metal-organic framework (Ln-MOF), we proposed an on-off dual-response biosensor for the sensitive and selective detection of TYR monophenolase. The Ln-MOF was prepared with Eu3+ and monoaromatic ligand dipicolinic acid (DPA), and it plays multiple functions such as fluorescent internal standard, chromaticity shift enhancement and fluorescence sensing. In alkaline boric acid (BA) buffer, L-tyrosine is converted into BA-levodopa by TYR monophenolase. Then, with the assistance of Eu-DPA, BA-levodopa is initiated by diethylaminepropyltrimethoxysilane (DAMO) to generate BA-levodopa polymer dots, which turn on strong blue fluorescence (crosslink-enhanced emission) and meanwhile quench the red fluorescence of Eu-DPA through enhanced photo-induced electron transfer. Thus, the sensitive and selective dual-response sensing to TYR monophenolase is achieved. Both DAMO and BA play significant roles in the synthesis of strong fluorescence polymer dots, and another key role of BA is to inhibit TYR diphenolase activity. Furthermore, chromaticity shift value-based quantification greatly improves the response linearity. The linear range is 0.05–2 U mL−1 (r = 0.9966), and the limit of detection is 0.004 U mL−1. The precise and accurate quantification of TYR monophenolase activity in saliva samples is realized (recovery of 96.9–102.0%, relative standard deviation < 9.56%). To our knowledge, it is the first highly-sensitive double-response biosensor for TYR monophenolase activity.

Ratiometric fluorescence and chromaticity dual-readout assay for β-glucuronidase activity based on luminescent lanthanide metal-organic framework

β-Glucuronidase (GCU) is a biomarker of many malignant tumors. The accurate and sensitive detection of GCU is of significance for the early diagnosis of diseases. Herein, we proposed a ratiometric fluorescence/chromaticity dual-readout assay method for GCU activity by integrating a luminescent lanthanide metal-organic framework (MOF) and fluorescence turn-on enzymolysis reaction. MOF-253 synthesized by Al3+ and 2,2′-bipyridine-5,5′-dicarboxylic acid was used as scaffold to prepare Eu3+@MOF-253 with red emission, which plays multiple roles in GCU assay including fluorescence internal standard, synergistic enzyme catalysis and chromaticity shift enhancement. 4-Methylumbelliferyl-β-glucuronide was selected as substrate and hydrolyzed by GCU to produce 4-methylumbelliferyl with blue emission, which can quench the fluorescence of Eu3+@MOF-253 due to internal filter effect. Therefore, the turn-on/off ratiometric fluorescence assay method of GCU was established, and it exhibits a wide linear range of 0.1–50 U L−1, low limit of detection (LOD) of 0.03 U L−1 and good selective response. Furthermore, a portable device with illuminometer as RGB signal readout was designed to perform the ratiometric chromaticity visual assay of GCU, which has the linear range of 0.2–40 U L−1 and the LOD of 0.06 U L−1. The dual-readout method was applied to detect GCU in human serum and shows high accuracy and precision (recovery of 92.4–114.1%, relative standard deviation < 7.9%). Both the ratiometric fluorescence and the ratiometric chromaticity assay get the same results as the classical colorimetric assay. To our knowledge, this is the first report on the ratiometric fluorescence/chromaticity dual-readout assay of GCU activity.

Continuous-flow rapid synthesis of wavelength-tunable luminescent lanthanide metal-organic framework nanorods by a microfluidic reactor

Lanthanide metal-organic frameworks (Ln-MOFs) have been widely used in fluorescence sensing, bioimaging and light emitting diode due to their excellent optical properties. However, the preparation of Ln-MOFs is energy and time-consuming due to the constraints of the conventional wet chemical methods. In this paper, a synthetic strategy for the rapid preparation of Ln-MOFs nanorods with adjustable emission wavelength in a microchannel reactor is proposed. Compared with the wet chemical methods, the efficient mass and heat transfer capability of the microchannel shortens the reaction time from 12 h to 50 min. More importantly, Ln-MOFs nanorods with different emission wavelengths can be easily prepared by adjusting the flow rate of different components of the microchannel, which can be adjusted in real-time according to the preparation needs. The result shows that the Ln-MOFs prepared by microfluidic method is in the shape of nanorods with widely emission wavelength from 470 nm (blue light) to 615 nm (red light). In addition, the fluorescence emission intensity of Ln-MOFs is confirmed to have a wide reversible temperature (30–220 ℃) and is expected to be used for high-precision temperature sensing in the future.

Controlled Assembly of Luminescent Lanthanide-Organic Frameworks via Post-Treatment of 3D-Printed Objects

Article HighlightsControlled 3D assembly of luminescent lanthanide metal–organic frameworks (LnMOFs) through additive manufacturing followed by posting-printing treatment, enabling the multiscale integration in a precisely controlled and facile manner.3D-printed LnMOFs objects with tunable fluorescence properties are caused by coordination and chelation of lanthanide ions, rendering a sub-millimeter resolution and high shape fidelity.A type of 3D assembled LnMOFs-based optical sensing platform showing response to small molecules such as acetone is presented.

Controllable Production of Micro-nanoscale Metal-Organic Frameworks Coatings on Cotton Fabric for Sensing Cu2+

Luminescent lanthanide metal-organic frameworks (ln-MOFs) is a promising materials for sensing. However, seeking ideal method to scale up in mass production and can be uniform on flexible substrate is still a great challenge. In this study, a novel and efficient process was employed for the fabrication of flexible and environmental copper ion-sensing materials using cotton fabric as a substrate. The micro-nanoscale Europium metal-organic frameworks (Eu-MOFs) was prepared through adding blocking reagent, and then cotton fabric was coated with the Eu-MOFs by hot pressing. The results show that controllable dense micro-nanoscale Eu-MOFs film was coated on the cotton fabric with different dipping and hot pressing times. The method is fast, simple, low-cost and suitable for production. The Eu-MOFs coated cotton fabric exhibits good photoluminescent properties. The selective sensing ability of Eu-MOFs coated fabric for Cu2+ over many other metal ions (K+, Cd2+, Ca2+, Pb2+, Na+, Zn2+, Ni2+, Mg2+, Al3+ and Co2+) is verified by emission spectra, and by the fact that the fluorescence intensity of the fabric significantly decreased with an increase in the concentration of Cu2+ (10−6—10−1 mol/L). This method provides a new path for the controllable production of MOFs-coated functional textiles for different applications, such as anti-counterfeiting, UV-protection, superhydrophobic, and sensing materials in the textile industry.

A multi-responsive chemosensor for highly sensitive and selective detection of Fe3+, Cu2+, Cr2O72- and nitrobenzene based on a luminescent lanthanide metal-organic framework.

Excessive release of some hazardous chemicals, such as Fe3+, Cu2+, Cr2O72- and nitrobenzene, may endanger public health and the environment; therefore, targeted effective sensing strategies are important. In this report, a series of lanthanide-based metal-organic frameworks (Ln-MOFs), namely {[Ln(dpc)(2H2O)]·(Hbibp)0.5}n (H4dpc = 2-(3',4'-dicarboxylphenoxy) isophthalic acid, bibp = 4,4'-bis(imidazolyl) biphenyl, for I-VI, Ln = La, Ce, Pr, Nd, Sm, and Eu) were hydrothermally synthesized and characterized. Single-crystal X-ray diffraction indicates that I-VI are isostructural and the lanthanide center is nine-coordinated with a distorted tetrakaidecahedral configuration. The as-synthesized Ln-MOFs are assembled into three-dimensional frameworks through the connections of dpc4- ligands and hydrogen bonding interactions. Notably, Eu-MOF (VI) behaves as a multi-responsive luminescent sensor toward Fe3+, Cu2+, Cr2O72- and nitrobenzene with high sensitivity, selectivity, stability and anti-interference ability against the coexistence of other ions or molecules based on high luminescence quenching efficiency. Additionally, Eu-MOF (VI) shows excellent luminescence stability and retains its structural integrity within the pH range of 2-12 in an aqueous solution and its solid sample maintains high thermodynamic stability up to 320 °C. Furthermore, the possible luminescence sensing mechanisms have been discussed in detail, and are supported by PXRD analysis, UV-vis spectroscopy, X-ray photoelectron spectroscopy (XPS) or density functional theory (DFT).

Luminescent lanthanide metal-organic framework test strip for immediate detection of tetracycline antibiotics in water

Tetracycline antibiotics (TCs) are a kind of commonly used antibiotics for treating infections, however, the overuse of TCs has adversely affected human health and the ecosystem. Thus, detection of TCs in water is important but challenging. In this work, a luminescent lanthanide metal-organic framework (LnMOF) sensor (1) for immediate detection of oxytetracycline (OTC) and tetracycline (TC) is developed. The sensor has high acid-base and water stability. Investigation reveals that among the 27 species of antibiotics, anions and cations under investigation, 1 shows highly selective sensing towards OTC and TC, and the detection is not disturbed by the presence of other species. The limit of detection (LOD) for OTC and TC are ultra-sensitive value of 1.95 and 2.77 nM, respectively. Investigation reveals the sensing mechanism is due to the inner filter effect. Further studies reveal that the sensor can be used in real sample monitoring. More importantly, test strips based on 1 are manufactured. They are an easy-to-use, low-cost, highly selective and sensitive sensing device for detecting OTC and TC. The sensing can be distinguished immediately and easily by the naked eyes, making it an excellent candidate to monitor OTC and TC in real use.

Luminescent Lanthanide Metal Organic Frameworks as Chemosensing Platforms towards Agrochemicals and Cations.

Since the first studies of luminescent sensors based on metal organic frameworks (MOFs) about ten years ago, there has been an increased interest in the development of specific sensors towards cations, anions, explosives, small molecules, solvents, etc. However, the detection of toxic compounds related to agro-industry and nuclear activity is noticeably scarce or even non-existent. In this work, we report the synthesis and characterization of luminescent lanthanide-based MOFs (Ln-MOFs) with diverse crystalline architectures obtained by solvothermal methods. The luminescent properties of the lanthanides, and the hypersensitive transitions of Eu3+ (5D0→7F2) and Tb3+ (5D4→7F5) intrinsically found in the obtained MOFs in particular, were evaluated and employed as chemical sensors for agrochemical and cationic species. The limit of detection (LOD) of Tb-PSA MOFs (PSA = 2-phenylsuccinate) was 2.9 ppm for [UO22+] and 5.6 ppm for [Cu2+]. The variations of the 4f–4f spectral lines and the quenching/enhancement effects of the Ln-MOFs in the presence of the analytes were fully analyzed and discussed in terms of a combinatorial “host–guest” vibrational and “in-silico” interaction studies.

Cryogenic Luminescent Tb/Eu-MOF Thermometer Based on a Fluorine-Modified Tetracarboxylate Ligand.

A fluorine-modified tetracarboxylic acid ligand, namely, 2'-fluoro-[1,1':4',1''-terphenyl]-3,3'',5,5''-tetracarboxylic acid (H4FTPTC), with suitable triplet energy excited state, was designed and applied to construct the luminescent lanthanide metal-organic frameworks (LnMOFs) for cryogenic temperature sensing. With the lanthanides codoping strategy, we developed a new Tb3+/Eu3+ mixed LnMOF system Tb1- xEu xFTPTC ( x = 0.05, 0.1, 0.2), which feature excellent linear responses to temperature with high relative sensitivity in the cryogenic range of 25-125 K. It was found that the relative sensitivity of such mixed LnMOF could readily be tuned by adjusting the incorporation amount of Eu3+ ions in the host framework. In addition, the energy transfer efficiency between the Tb3+ and Eu3+ ions in the framework with different Tb3+/Eu3+ ratios are also investigated and discussed.

Monitoring Ultraviolet Radiation Dosage Based on a Luminescent Lanthanide Metal-Organic Framework.

A luminescent lanthanide metal-organic framework [Tb7(OH)8(H2O)6(IDA)3(COO)3]·4Cl·2H2O (Tb-IDA, IDA = iminodiacetic acid) was hydrothermally synthesized and structurally characterized. Monitoring ultraviolet radiation was achieved by correlating the dosage with the luminescence color change in doped Gd99Tb0.1Eu0.9-IDA compound. A linear relationship is developed across a broad range from blue to yellow within a CIE chromaticity diagram.

Rapid Detection of the Biomarkers for Carcinoid Tumors by a Water Stable Luminescent Lanthanide Metal–Organic Framework Sensor

AbstractSerotonin (5‐hydroxytryptamine, HT), a neurotransmitter, and its main metabolite 5‐hydroxyindole‐3‐acetic acid (HIAA) are biomarkers for carcinoid tumors. They can be quantitatively detected by a new luminescent sensor based on a water stable lanthanide metal–organic framework (Ln‐MOF). This Ln‐MOF features a (3,4)‐connected topology containing 1D channels occupied by lattice water molecules. Luminescent studies reveal that high luminescence quenching efficiency occurs upon the addition of HT and HIAA. The Ln‐MOF also displays excellent sensitivity with fast response within 1 min, good reusability, and detection limits as low as 0.66 and 0.54 × 10−6m for HT and HIAA, respectively. In addition, the sensing function exhibits excellent selectivity even in the presence of other neurotransmitters and the main coexisting species in blood plasma and urine.

Efficient pure white light emission based on a three-component La:Eu,Tb-doped luminescent lanthanide metal–organic framework

A three-component Eu and Tb-doped La complex based on a semirigid tricarboxylate ligand is successfully constructed with high-efficiency white light emission (Φ = 11.22% at 345 nm).

Highly luminescent Ln-MOFs based on 1,3-adamantanediacetic acid as bifunctional sensor

A series of lanthanide metal-organic-frameworks (Ln-MOFs) are synthesized under mild hydrothermal condition by introducing the ligand of 1,3-adamantanediacetic acid (H2ADA). They are three dimentional (3D) structures and have the formula of [Ln(ADA)1.5(phen)]n (Ln3+=Eu3+1a, Gd3+1b, Tb3+1c, La3+1d, Ce3+1e, Pr3+1f, Nd3+1g, Y3+1h; phen=1,10-phenanthroline). These Ln-MOFs are fully characterized by single-crystal X-ray diffraction, PXRD, TGA, EA and FT-IR. Luminescence properties, including luminescence spectra, luminescence decay lifetimes and luminescence quantum yields (QYs) are analyzed in detail. Eu3+ complex of 1a shows highly luminescence QYs of 58.61%, which due to that the triplet state of phen competes well with the excited emission state of Eu3+. Further investigation reveals that 1a is a bifunctional sensor, which can be used as a turn-off luminescence sensor for detecting Ni2+ and turn-on luminescence sensor for probing Val at the same time. Interestingly, the limit of detect (LOD) for sensing Ni2+ is an ultrahigh sensitive value of 1.0×10−9M (5.9×10−5mg/L), which is lower than the Chinese environmental quality standard (0.5mg/L of total Ni2+ content, GB25467-2010), and it is the most sensitive chemosensor for detecting Ni2+, to the best of our knowledge. Investigation also reveals there is a good linear relationship between luminescence intensity and the concentration of Ni2+ in 0.2–0.6μM. The sensing mechanism for detecting Ni2+ and Val are also discussed.