Versatile bimetallic lanthanide metal-organic frameworks for tunable emission and efficient fluorescence sensing

Designed Eu3+ functionalized Zr-MOF-808 probe for highly sensitive monitoring multiple dyes

Dyes detection remains a serious task because of their high toxicity. In present work, designed Eu³⁺ functionalized Zr-metal-organic framework (Eu³⁺@Zr-MOF-808) as fluorescent probe was constructed via post-synthetic modification (PSM) for rapid monitoring four most commonly used dyes (malachite green (MG), brilliant green (BG), alizarin red S (ARS), indigo red (IDR)). Systematic exploring on the sensing mechanism reveals that fluorescence resonance energy transfer (FRET) for BG, MG and IDR and inner filter effect (IFE) for ARS contribute to the realization of the fluorescence quenching process. It exhibits excellent sensing performances with low limit of detection (LOD) of 32, 58, 77 and 133 nM for BG, IDR, MG and ARS, respectively. The as-constructed Eu³⁺@Zr-MOF-808 was demonstrated to be a highly sensitive probe for screening of MG in fish pond and IDR in printing wastewater with satisfying results. Moreover, a portable test reagent bottle has been developed for visual on-site screening of sample containing dyes with naked eyes under UV light. This is the first attempt to construct the Eu³⁺@Zr-MOF-808 probe for sensingmultiple dyes in real samples and demonstrates promising applications in water quality monitoring.

Recent Advances in Developing Lanthanide Metal-Organic Frameworks for Ratiometric Fluorescent Sensing

Fluorescent probes have attracted special attention in developing optical sensor systems due to their reliable and rapid fluorescent response upon reaction with the analyte. Comparing to traditional fluorescent sensing systems that employ the intensity of only a single emission, ratiometric fluorescent sensors exhibit higher sensitivity and allow fast visual screening of analytes because of quantitatively analyzing analytes through the emission intensity ratio at two or more wavelengths. Lanthanide metal–organic frameworks (LnMOFs) are highly designable multifunctional luminescent materials as lanthanide ions, organic ligands, and guest metal ions or chromophores are all potential sources for luminescence. They thus have been widely employed as ratiometric fluorescent sensors. This mini review summarized the basic concept, optical features, construction strategies, and the ratiometric fluorescent sensing mechanisms of dual-emitting LnMOFs. The review ends with a discussion on the prospects, challenges, and new direction in designing LnMOF-based ratiometric fluorescent sensors.

Selective Sensing of Cu2+ and Fe3+ Ions with Vis-Excitation using Fluorescent Eu3+-Induced Aggregates of Polysaccharides (EIAP) in Mammalian Cells and Aqueous Systems

Fluorescent lanthanide complexes have favorable features for fluorescence-based sensors compared to organic fluorophores and quantum dots. They exhibit very long fluorescence lifetimes, sharp emission bands, and stability with respect to photo-bleaching, without blinking. However, these complexes are usually hydrophobic, and many are excited by UV light, making them hazardous and incompatible with aqueous environments and biological samples. In this work, the strong fluorescent Eu³⁺-induced aggregates of polysaccharides (EIAP) was used to improve their aqueous solubility, and to tune the appropriate excitation wavelength in the visible range for avoiding toxicity of UV light in biological applications. The complexes exhibit bright fluorescence with an excitation maximum in the visible range, near 405 nm. EIAP 3 also exhibit rapid quenching response in the presence of transition metal ions. This enables the detection of Cu²⁺ and Fe³⁺ below 1 ppm. The reverse of quenching response of copper by the addition of a chelating agent makes it possible to recover the fluorescence property. Successfully, the EIAP exhibit cytocompatibility with mammalian cells. Thus, these new polysaccharide-based complexes have the potential for rapid, sensitive and selective metal ion sensors for the environmental systems.

In situ self-assembled cationic lanthanide metal organic framework membrane sensor for effective MnO4- and ascorbic acid detection

Developing portable membrane sensors to accurately detect the biomolecule ascorbic acid (AA) is extremely important for food safety and human health. Herein, we successfully design and synthesize a novel cationic metal organic framework (Eu-pbmc, Hpbmc = 2-(pyridine-2-yl)-1H-benzimidazole-5-carboxylic acid) and assemble polyacrylonitrile/Eu-pbmc membrane (PEM) by an in-situ growth strategy. Benefiting from the appreciable loading of Eu-pbmc nanoparticles and high water permeation flux, PEM possesses effective detection for MnO₄^- with a limit of detection (LOD) of 17 nM. Utilizing the cationic porous framework, we load MnO₄^- into PEM and construct a "on-off-on" system for effective AA detection. The oxidative MnO₄^- can be reduced by AA and the resulting turn-on luminescence can reflect the concentration of AA. Compared with pure Eu-pbmc crystals, PEM exhibits improved AA detection performance with LOD of 48 nM and detection time of 1 min via a concise detection operation. The stable membrane sensor realizes an accurate detection in real biological samples, meeting the practical requirement. Moreover, an IMP logic gate is helpful to analyze MnO₄^- and AA in water. The proposed novel luminescence platform as well as reasonable "on-off-on" luminescence mode provide a promising method for AA detection.

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

Complex multiscale assemblies of metal-organic frameworks are essential in the construction of large-scale optical platforms but often restricted by their bulk nature and conventional techniques. The integration of nanomaterials and 3D printing technologies allows the fabrication of multiscale functional architectures. Our study reports a unique method of controlled 3D assembly purely relying on the post-printing treatment of printed constructs. By immersing a 3D-printed patterned construct consisting of organic ligand in a solution of lanthanide ions, in situ growth of lanthanide metal-organic frameworks (LnMOFs) can rapidly occur, resulting in macroscopic assemblies and tunable fluorescence properties. This phenomenon, caused by coordination and chelation of lanthanide ions, also renders a sub-millimeter resolution and high shape fidelity. As a proof of concept, a type of 3D assembled LnMOFs-based optical sensing platform has demonstrated the feasibility in response to small molecules such as acetone. It is anticipated that the facile printing and design approach developed in this work can be applied to fabricate bespoke multiscale architectures of functional materials with controlled assembly, bringing a realistic and economic prospect.

Bimetallic Lanthanide-Organic Framework Membranes as a Self-Calibrating Luminescent Sensor for Rapidly Detecting Antibiotics in Water

Rapid, facile, and reliable recognition of different antibiotics by self-calibrating luminescent sensors are important for practical requirements. Herein, we design and synthesize a series of Eu_1-xTb_x-MOF using a flexible ligand H₄L (5,5'-(propane-1,3-diylbis(oxy))di-isophthalic acid). With changing reactant time, submicrometer bimetallic SMOF-10-10h with homogeneous morphology was achieved and further fabricated MOF-based membrane combining with polymer materials. A luminescent study indicated that the bimetallic SMOF-10-10h membrane possesses a legible emission peak for Eu³⁺ and Tb³⁺ ions, which can act as a self-calibrating luminescent probe for efficiently sensing different antibiotics within a certain concentration range through two-dimensional (2D) readouts based on the emission intensity ratio. Our work first reports an inexpensive and convenience bimetallic MOF-based membrane as a luminescent sensor with self-calibrating to detect various antibiotics, which makes it a potential luminescent sensor for beneficial application.

Sensing mechanism elucidation of a europium(III) metal-organic framework selective to aniline: A theoretical insight by means of multiconfigurational calculations

A theoretical procedure, via quantum chemical computations, to elucidate the detection principle of the turn-off luminescence mechanism of an Eu-based Metal-Organic Framework sensor (Eu-MOF) selective to aniline, is accomplished. The energy transfer channels that take place in the Eu-MOF, as well as understanding the luminescence quenching by aniline, were investigated using the well-known and accurate multiconfigurational ab initio methods along with sTD-DFT. Based on multireference calculations, the sensitization pathway from the ligand (antenna) to the lanthanide was assessed in detail, that is, intersystem crossing (ISC) from the S₁ to the T₁ state of the ligand, with subsequent energy transfer to the ⁵ D₀ state of Eu³⁺ . Finally, emission from the ⁵ D₀ state to the ⁷ F_J state is clearly evidenced. Otherwise, the interaction of Eu-MOF with aniline produces a mixture of the electronic states of both systems, where molecular orbitals on aniline now appear in the active space. Consequently, a stabilization of the T₁ state of the antenna is observed, blocking the energy transfer to the ⁵ D₀ state of Eu³⁺ , leading to a non-emissive deactivation. Finally, in this paper, it was demonstrated that the host-guest interactions, which are not taken frequently into account by previous reports, and the employment of high-level theoretical approaches are imperative to raise new concepts that explain the sensing mechanism associated to chemical sensors.

New Microporous Lanthanide Organic Frameworks. Synthesis, Structure, Luminescence, Sorption, and Catalytic Acylation of 2-Naphthol

New metal-organic frameworks (MOF) with lanthanum(III), cerium(III), neodymium(III), europium(III), gadolinium(III), dysprosium(III), and holmium(III)] and the ligand precursor 1,3,5-tris(4-carboxyphenyl)-2,4,6-trimethylbenzene (H3L) were synthesized under solvothermal conditions. Single crystal x-ray analysis confirmed the formation of three-dimensional frameworks of [LnL(H2O)2]n·xDMF·yH2O for Ln = La, Ce, and Nd. From the nitrogen sorption experiments, the compounds showed permanent porosity with Brunauer-Emmett-Teller (BET) surface areas of about 400 m2/g, and thermal stability up to 500 °C. Further investigations showed that these Ln-MOFs exhibit catalytic activity, paving the way for potential applications within the field of catalysis.

Divergent Adsorption-Dependent Luminescence of Amino-Functionalized Lanthanide Metal-Organic Frameworks for Highly Sensitive NO2 Sensors

A novel gas sensing mechanism exploiting lanthanide luminescence modulation upon NO₂ adsorption is demonstrated here. Two isostructural lanthanide-based metal-organic frameworks (MOFs) are used, including an amino group as the sensitive recognition center for NO₂ molecules. The transfer of energy from the organic ligands to Ln is strongly dependent on the presence of NO₂, resulting in an unprecedented photoluminescent sensing scheme. Thereby, NO₂ exposition triggers either a reversible enhancement or a decrease in the luminescence intensity, depending on the lanthanide ion (Eu or Tb). Our experimental studies combined with density functional theory and complete active space self-consistent field calculations provide an understanding of the nature and effects of NO₂ interactions within the MOFs and the signal transduction mechanism.

The Fluorescence Property of Zirconium-Based MOFs Adsorbed Sulforhodamine B

Sulforhodamine B (SRB) is widely utilized for cell staining and laser field. But its application is limited by aggregation-caused quenching (ACQ). In this work, we evaluated the use of UiO-66 and UiO-67 of Zr-based metal organic frameworks (Zr-MOFs) as the host to adsorb SRB molecules due to the high stabily and good loading capacity of Zr-MOFs. The fluorescence properties of the compounds were then discussed respectively. Due to the aperture difference between UiO-66 and UiO-67, they showed distinct fluorescence properties after loading SRB. When the concentration reaches 5 ppm, fluorescence quenching begins to occur in SRB@UiO-66, while it occurs in SRB@UiO-67 at 2 ppm. The solution of quenching phenomenon could open new avenues for the extensive use of SRB.

Terbium-based metal-organic frameworks: highly selective and fast respond sensor for styrene detection and construction of molecular logic gate

Volatile organic compounds (VOCs) are extremely harmful to the human body and environment, thus it is greatly meaningful and urgent to detect VOCs. In this work, terbium-based metal-organic frameworks (Tb-MOFs) have been prepared successfully via a facile and efficient route. These well-constructed Tb-MOFs architectures exhibit characteristic green emission of Tb³⁺ ion upon excitation of UV light. It is noteworthy that the Tb-MOFs can act as a convenient and efficient luminescent sensor for VOCs. Especially, the Tb-MOFs displayed high selectivity and superior sensitivity towards the sensing of styrene solution and vapor through fluorescence quenching mechanism. The Tb-MOFs can realize fast detection for styrene vapor with a response time of 30 s. The mechanism of fluorescence quenching of Tb-MOFs induced by styrene was also discussed. More importantly, we have designed a logic gate operation with the combination of the sensor for the intelligent detection of styrene. This developed type of lanthanide luminescent metal-organic frameworks (Ln-MOFs) based on the combination of fluorescence sensor and logic gate has a great application prospect in the detection of VOCs in daily life.

Three coordination polymers with regulated coordination interactions as fluorescent sensors for monitoring purine metabolite uric acid

A facile optical sensor for uric acid (UA), an early pathological signature for the metabolic function of humans, was developed based on water-stable coordination polymers (CPs). Herein, three new isostructural fluorescent CPs, [Ln(TCPB)(DMF)3]n (Ln = La, CP 1; Ce, CP 2 and Pr, CP 3; H3TCPB = 1,3,5-tris(1-(2-carboxyphenyl)-1H-pyrazol-3-yl)benzene), with various metal ions were solvothermally synthesized. Significantly, by regulating the metal-organic coordination interactions, the fabricated CP 3 can quantitatively recognize UA with higher sensitivity compared with CP 1 and CP 2. The mechanism for the sensing properties further demonstrates the best performance of CP 3 and the excellent selectivity for UA monitoring. This work represents the strategy of designing fluorescent CP sensors to determine UA and provides a convenient approach for developing analysis platforms for the assessment of related disease progress and human health monitoring.

Selective sensing of Fe3+ ions in aqueous solution by a biodegradable platform based lanthanide metal organic framework

As a significant metal ion in the environmental and biological systems, excess or shortage of Fe³⁺ from the organism can cause a host of diseases. So it is very urgent to explore an explicit, rapid and recoverable method for the detection of Fe³⁺ ions. Herein, a novel and flexible ligand containing 12 carboxyl groups (BHM-COOH) is used for the structure of a series of luminescent Eu³⁺/Tb³⁺-metal-organic frameworks (MOFs). A reliable and convenient luminescent detection platform is constructed by combining polylactic acid (PLA) film with Eu_0.24Tb_0.76-BHM-COOH. More importantly, the luminescent platform can highly sensitive to sense Fe³⁺ ions through fluorescence quenching (Stern-volmer constant Ksv = 1.27 × 10⁴ M^-1 for Fe(NO₃)₃), and detection limit can be as low as 4.47 μM. The sensing mechanism is ascribed to the fluorescence quenching caused by the competitive absorption between Eu_0.24Tb_0.76-BHM-COOH and Fe³⁺ ion. At the same time, the sensor can be reused many times. These exciting results indicate that Eu_0.24Tb_0.76-BHM-COOH film can serve as a promising multi-responsive luminescent sensor for environmental pollutant monitoring.

Metal-Organic Frameworks with Multiple Luminescence Emissions: Designs and Applications

Emissive species are powerful for luminescent detection with high sensitivity and simple procedure and for light-emitting diode (LED) lighting because of their high efficiency, long lifetime, and low energy consumption. Here we propose the concept of multiple luminescence emissions from a single matrix or species under single-wavelength excitation. Multiemission not only realizes the high sensitivity of luminescence sensing but also possesses the capacity of self-reference for environment-free interferences. The color change is also convenient for visible detection. In multiemission species, every emissive center responds to a specific analyte to improve the efficiency for multiple-target detection. Multiemission also extends the applications to anticounterfeiting, colorful LEDs, and information storage. To date, it is still challenging to combine more than one type of emissive center in a single matrix or species. Obtaining multiemission under single-wavelength excitation also needs exquisite design. Metal-organic frameworks (MOFs) are porous hybrid assemblies prepared with metal ions and organic ligands. Metal nodes and ligands with large π-conjugated systems have the potential for the construction of luminescent MOFs. Abundant and diverse precursors provide the possibility to prepare MOFs with multiple luminescence emissions. The pores or channels of MOFs also act as hosts to encapsulate luminescent guest species as additional emissive sites. In this Account, we propose the concept of multiple-luminescence MOFs (ML-MOFs) and summarize the recent research progress on their designs, constructions, and applications reported by our group and others. ML-MOFs are MOFs that possess more than one emissive center under single-wavelength excitation. Six different kinds of construction strategies of ML-MOFs are introduced: (1) multiemission from both metal nodes and ligands in single MOFs; (2) use of mixed-metal nodes as multiemission centers in single MOFs; (3) combination of different emissive MOFs as a whole to achieve multiemission application; (4) host-guest emissions from emissive MOFs after encapsulation of luminescent guest species; (5) organization of different emissive ligands in a single MOF for multiemission; and (6) use of single ligands exhibiting dual emission to prepare ML-MOFs. We also discuss the mechanisms that realize multiple emissions from MOFs under single-wavelength excitation, such as the antenna effect and excited-state intramolecular proton transfer. The applications of ratiometric sensing, LED lighting, anticounterfeiting, and information storage are summarized. With this Account, we hope to spark new ideas and to inspire new endeavors in the design and construction of ML-MOFs, especially with postsynthetic techniques such as postsynthetic modification, postsynthetic exchange, and postsynthetic deprotection, to promote the applications of MOFs in sensing, lighting, information storage, and others.

Multicenter Metal-Organic Framework-Based Ratiometric Fluorescent Sensors

Metal-organic frameworks (MOFs) with multiple emission centers are newly emerging as ratiometric sensors owing to their high sensitivity and high selectivity toward a wide range of targeted functional species. Energy transfer between the light-absorbing group and emission centers and between different emission centers is the key to rationally design and synthesize MOF-based ratiometric sensors. A good match between the energy levels of the light-absorbing groups and emission centers is the prerequisite for MOF-based sensors to exhibit multiple emissions, and a good match of the MOF-based sensors and those of the targeted species can increase the sensitivity and selectivity, but this match is highly challenging to obtain via synthesis. MOFs with multiple emission centers can be produced by functionalizing MOFs with multiple lanthanide centers, organic luminophores, dyes, carbon dots, and other such emissive groups. In this progress report, recent advances in the strategies for synthesizing MOFs with multiple emission centers and their applications for ratiometric sensing of solution conditions, including the pH value, and ion, organic molecule, and biomolecule concentrations, are summarized, as are the related sensing mechanisms.

A water-stable terbium metal–organic framework with functionalized ligands for the detection of Fe3+ and Cr2O72− ions in water and picric acid in seawater

A novel Tb-MOF-A was fabricated by functionalized ligands and Tb³⁺, which displays high fluorescence, water stability up to 21 days and rapid, cyclic, simultaneous detection of Fe³⁺, Cr₂O₇²⁻ ions in water and picric acid in seawater.

Different effects in the selective detection of aniline and Fe3+ by lanthanide-based coordination polymers containing multiple reactive sites

Isostructural Ln-CPs (1-Eu and 2-Tb) show almost the same high detection ability for Fe³⁺ and different detection abilities for aniline. The detection difference was studied through PXRD, UV-vis, luminescence lifetimes and Hirshfeld surface analysis.

Sonochemical Synthesis of Carbon Dots/Lanthanoid MOFs Hybrids for White Light-Emitting Diodes with High Color Rendering

Although lanthanoid metal-organic frameworks (Ln-MOFs) have been widely developed for white light-emitting diodes (WLEDs), the color rendering index (CRI) values are still lower than 80. To overcome this limitation, a series of CDs/Ln-MOFs hybrids, namely, CDs-2@Ln-MOF, CDs-3@Ln-MOF, and CDs-4@Ln-MOF containing blue-emitting CDs and yellow-emitting bimetallic [(Eu_1.22Tb_0.78(1,4-phda)₃(H₂O)](H₂O)₂ were prepared via sonication at room temperature to restrict the self-quenching of CDs in composite materials. The as-synthesized composite materials were investigated by Fourier transform infrared, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and photoluminescence. The luminescent color of the materials can be adjusted by varying the amount of CDs and excitation wavelengths. The resulting CDs-3@Ln-MOF achieved excellent CRI up to 93 with the ideal Commission International ed'Eclairage coordinate (0.334, 0.334) and appropriate correlated color temperature (CCT) (5443 K). In addition, the tunable multicolored luminescence based on single and bimetallic Eu_xTb_2-x(1,4-phda)₃(H₂O)](H₂O)₂, x = 0, 0.73, 1.22, 1.57, 1.94, and 2, were applied as the luminescent security inks for anti-counterfeiting application through encoding/decoding and rewritable data.

Dy(III)-Based Metal-Organic Framework as a Fluorescent Probe for Highly Selective Detection of Picric Acid in Aqueous Medium

A dysprosium metal-organic framework, {[Dy(μ₂-FcDCA)_1.5(MeOH)(H₂O)]·0.5H₂O}_n (1), where FcDCA = 1,1'-ferrocene dicarboxylic acid, was prepared by slow-diffusion technique at room temperature. The crystal structure analysis of 1 by single-crystal X-ray diffraction reveals different binding modes of FcDCA linkers coordinated with Dy(III) metal ions, which forms continuous porous two-dimensional (2D) infinite framework. The resulting 2D layers are linked by π···π interactions to build three-dimensional (3D) supramolecular framework. Observably, this thermally stable 3D architecture was topologically simplified as a three-connected uninodal net with fes topology. Furthermore, the practical applicability of 1 was investigated as a fluorescence sensor for the sensitive detection of picric acid in aqueous medium with an impressive detection limit of 0.71 μM with quenching constant (K_SV) quantified to be 8.55 × 10⁴ M^-1. The distinguished selectivity in the presence of other nitroaromatics suggests the possible incorporation of 1 in real-world futuristic diagnostic kits. Additionally, the electrochemical behavior of 1 exhibits reversible in nature attributed to the ferrocene/ferrocenium cation.

Excitation-Dependent Long-Life Luminescent Polymeric Systems under Ambient Conditions

Organic room temperature luminescent materials present a unique phosphorescence emission with a long lifetime. However, many of these materials only emit single blue or green color in spite of external stimulation, and their color tunability is limited. Herein, we report a rational design to extend the emission color range from blue to red by controlling the doping of simple pyrene derivatives into a robust polymer matrix. The integration of these pyrene molecules into the polymer films enhances the intersystem crossing pathway, decreases the first triplet level of the system, and ensures the films show a sensitive response to excitation energy, finally yielding excitation-dependent long-life luminescent polymeric systems under ambient conditions. These materials were used to construct anti-counterfeiting patterns with multicolor interconversion, presenting a promising application potential in the field of information security.

Rotation Restricted Emission and Antenna Effect in Single Metal-Organic Frameworks

Aggregation induced-emission (AIE) and antenna effects are important luminescence behaviors. Thus, investigating their emission mechanisms and revealing their behaviors have become critical but challenging. Here we design and prepare metal-organic frameworks (MOFs) with an AIE ligand (i.e., tetrakis(4-carboxyphenyl)pyrazine (L1)) and Ln³⁺ ions (including Eu³⁺, Tb³⁺, and Gd³⁺). The emission from L1 is gradually enhanced during the formation of the MOFs because coordination restricts the intramolecular rotation. Thus, the emission is called as coordination-induced emission (CIE) with the same restriction of intramolecular rotation mechanism as AIE. Meanwhile, benzene rings twist to adapt to the MOFs' rigid structure, so the emission blueshifts gradually, as an additional evidence of CIE. Both AIE and CIE are "rotation-restricted emission (RRE)". Eu³⁺ ions exhibit the strongest emission with gradually enhanced intensity during the formation of L1-Eu MOF. Combined with emission properties from Tb³⁺ and Gd³⁺ ions, the antenna effect is verified. We also validate the conditions for the efficient sensitization of Ln³⁺ ions experimentally and refresh the threshold value of the energy gap between triplet state of a ligand and excited state of Ln³⁺ ions to 3000 cm^-1. Thus, RRE and antenna effects are revealed and validated simultaneously. Because CIE of L1 and antenna effect emission from Eu³⁺ ions are enhanced simultaneously as strong dual emissions, ratiometric fluorescence detection is realized with the detection of arginine as a model. Our results incorporate AIE and CIE into RRE, which provides explicit information for the construction and application of emission systems with AIE ligands as building blocks. MOFs are also extended to explore the emission mechanism and the energy transfer between ligands and metal ions.

Versatile Polydopamine Platforms: Synthesis and Promising Applications for Surface Modification and Advanced Nanomedicine

As a mussel-inspired material, polydopamine (PDA), possesses many properties, such as a simple preparation process, good biocompatibility, strong adhesive property, easy functionalization, outstanding photothermal conversion efficiency, and strong quenching effect. PDA has attracted increasingly considerable attention because it provides a simple and versatile approach to functionalize material surfaces for obtaining a variety of multifunctional nanomaterials. In this review, recent significant research developments of PDA including its synthesis and polymerization mechanism, physicochemical properties, different nano/microstructures, and diverse applications are summarized and discussed. For the sections of its applications in surface modification and biomedicine, we mainly highlight the achievements in the past few years (2016-2019). The remaining challenges and future perspectives of PDA-based nanoplatforms are discussed rationally at the end. This timely and overall review should be desirable for a wide range of scientists and facilitate further development of surface coating methods and the production of PDA-based materials.

Highly selective and sensitive long fluorescence lifetime polyurethane foam sensor based on Tb-complex as chromophore for the detection of H2PO4- in water

Developing novel rare-earth complexes to rapidly and reliably sensing anions in pure water is highly challenging. Here, a series of long fluorescence lifetime polyurethane foam bonded Tb(BAA)₃ chromophore porous material (Tb-PUFs) have been designed and synthesized via a simple one-step co-polycondensation reaction as an efficient fluorescent sensor for H₂PO₄^- in pure water. All Tb-PUFs exhibited strong green emission and long fluorescence lifetime in water, which was ascribed to Tb-complex can be dispersed very well in polyurethane foam, effectively avoiding the emission quenching of Tb³⁺ ions caused by water molecules vibration. The titration experimental results showed that precursor Tb(BAA)₃ can effective recognize F^-, CH₃COO^-, and H₂PO₄^- in DMSO solution. Interestingly, Tb-PUFs can only selectively recognize H₂PO₄^- in pure water, this phenomenon can be explained that H₂PO₄^- is acidic, and can occur deprotonation with -NH group of ligand BAA, thus making the fluorescence quenching effect was more sensitive for H₂PO₄^- in pure water. In addition, the sensing ability of Tb-PUFs for H₂PO₄^- is highly reversible by washing them with deionized water for three times. In a word, all results implied that Tb-PUFs was an excellent candidate for H₂PO₄^- ions detection selectively in pure water.

Photoluminescent organisms: how to make fungi glow through biointegration with lanthanide metal-organic frameworks

We show that filamentous fungi can emit green or red light after the accumulation of particulate lanthanide metal-organic frameworks over the cell wall. These new biohybrids present photoluminescence properties that are unaffected by the components of the cell wall. In addition, the fungal cells internalise lanthanide metal-organic framework particles, storing them into organelles, thereby making these materials promising for applications in living imaging studies.

White-Light-Emitting Decoding Sensing for Eight Frequently-Used Antibiotics Based on a Lanthanide Metal-Organic Framework

Developing multi-selective luminescence sensing technology to differentiate serial compounds is very important but challenging. White-light-emitting decoding sensing based on lanthanide metal-organic frameworks (Ln-MOFs) is a promising candidate for multi-selective luminescence sensing application. In this work, three isomorphic Ln-MOFs based on H₃dcpcpt (3-(3,5-dicarboxylphenyl)-5-(4-carboxylphenl)-1H-1,2,4-triazole) ligand, exhibiting red, blue, and green emission, respectively, have been synthesized by solvothermal reactions. The isostructural mixed Eu/Gd/Tb-dcpcpt is fabricated via the in-situ doping of different Ln³⁺ ions into the host framework, which can emit white light upon the excitation at 320 nm. It is noteworthy that this white-light-emitting complex could serve as a convenient luminescent platform for distinguishing eight frequently-used antibiotics: five through luminescence-color-changing processes (tetracycline hydrochloride, yellow; nitrofurazone, orange; nitrofurantoin, orange; sulfadiazine, blue; carbamazepine, blue) and three through luminescence quenching processes (metronidazole, dimetridazole, and ornidazole). Moreover, a novel method, 3D decoding map, has been proposed to realize multi-selective luminescence sensing applications. This triple-readout map features unique characteristics on luminescence color and mechanism. The mechanism has been systematically interpreted on the basis of the structural analysis, energy transfer and allocation process, and peak fitting analysis for photoluminescence spectra. This approach presents a promising strategy to explore luminescent platforms capable of effectively sensing serial compounds.

Luminescent europium(iii) and terbium(iii) complexes of β-diketonate and substituted terpyridine ligands: synthesis, crystal structures and elucidation of energy transfer pathways

A series of coordinatively saturated Ln^III complexes: [Ln(R-TPY)(TTA)₃] (1–6) were designed and structurally characterized and plausible energy transfer (ET) pathways determined using a theoretical method.

Ratiometric fluorescence detection of trace water in an organic solvent based on bimetallic lanthanide metal–organic frameworks

A highly sensitive sensor Tb97.11Eu2.89-L1, which is an excellent water-sensing material for detecting trace water in an organic solvent, is reported.