Color-Tunable and High-Efficiency Dye-Encapsulated Metal-Organic Framework Composites Used for Smart White-Light-Emitting Diodes

Natural Pigments-Based Two-Component White Light Emitting Systems

In this paper, a new class of two component white light emitting systems viz, JaB (java plum + beetroot) {I}, and CaB (carrot + beetroot) {II} were developed through resonance energy transfer (RET) phenomenon by using a fruit (java plum) and two vegetable (carrot and beetroot) extracts. In these white light emitting systems, java plum and carrot are the donors while beetroot is the acceptor. The primary fluorescent pigments present in the natural extracts (i.e., anthocyanin in java plum, β-carotene in carrot, and betanin in beetroot) were responsible for the white light emission. The CIE (Commission Internationale d'Eclairage) coordinates for I and II were {0.32, 0.34} and {0.33, 0.33}, respectively, in solution phase. Interestingly, the white light emission (WLE) was also achieved in agar-agar gel medium. In gel medium, the CIE values were {0.31, 0.34} and {0.33, 0.32} for I and II, respectively. The donor-acceptor distance (r) for I and II were found to be 0.5 and 0.4 nm, respectively. Furthermore, the rate of energy transfer was also quantified with the values of 2.78 × 109 s-1 for JaB (I) and 1.02 × 108 s-1 for CaB (II) systems. The mechanistic investigation of the two white light systems was further supported by DFT studies.

A dual-emitting Rhodamine B-encapsulated Zn-based MOF for the selective sensing of Chromium(VI)

A Rhodamine B-Zn-MOF composite (RhB-Zn-MOF) with dual emission intensity was synthesized through one pot synthesis by in-situ encapsulation of Rhodamine-B dye on a new Zn-MOF metal-organic framework [(Zn(OAc)2(4-BrIPh) (1,10-phenonthroline)(H2O)].H2O, (4-BrIPh = 4-Bromoisophthalic acid). The synthesized encapsulated material was characterized by elemental analysis, FTIR, UV-Visible spectroscopy, TGA, single crystal and powder X-ray diffraction and photoluminescence spectroscopy. The results showed that the synthesized composite, RhB-Zn-MOF could be used as an efficient probe for the selective sensing of Cr(VI) in the presence of Cr(III) as well as other metal ions.

Exploiting the photophysical features of DMAN template in ITQ-51 zeotype in the search for FRET energy transfer

The combination between photoactive molecules and inorganic structures is of great interest for the development of advanced materials in the field of optics. Particularly, zeotypes with extra-large pore size are attractive because they allow the encapsulation of bulky dyes. The microporous aluminophoshate Mg-ITQ-51 (IFO-type structure) represents an ideal candidate because of the synergic combination of two crucial features: the IFO framework itself, which is composed of non-interconnected one-dimensional extra-large elliptical channels with a diameter up to 11 Å able to host bulky guest species, and the particular organic structure-directing agent used for the synthesis (1,8-bis(dimethylamino)naphthalene, DMAN), which efficiently fills the IFO pores, and is itself a photoactive molecule with interesting fluorescence properties in the blue range of the visible spectrum, thus providing a densely-incorporated donor species for FRET processes. Besides, occlusion of DMAN dye in the framework triggers a notable improvement of its fluorescence properties by confinement effect. To extend the action of the material and to mimic processes such as photosynthesis in which FRET is essential, two robust laser dyes with bulky size, rhodamine 123 and Nile Blue, have been encapsulated for the first time in a zeolitic framework, together with DMAN, in a straightforward one-pot synthesis. Thus, photoactive systems with emission in the entire visible range have been achieved due to a partial FRET between organic chromophores protected in a rigid aluminophosphate matrix.

Fluorescence detection platform of metal-organic frameworks for biomarkers

Sensitive and selective detection of biomarkers is crucial in the study and early diagnosis of diseases. With the continuous development of biosensing technologies, fluorescent biosensors based on metal-organic frameworks have attracted increasing attention in the field of biomarker detection due to the combination of the advantages of MOFs, such as high specific surface area, large porosity, and structure with tunable functionality and the technical simplicity, sensitivity and efficiency and good applicability of fluorescent detection techniques. Therefore, researchers must understand the fluorescence response mechanism of such fluorescent biosensors and their specific applications in this field. Of all biomarkers applicable to such sensors, the chemical essence of nucleic acids, proteins, amino acids, dopamine, and other small molecules account for about a quarter of the total number of studies. This review systematically elaborates on four fluorescence response mechanisms: metal-centered emission (MC), ligand-centered emission (LC), charge transfer (CT), and guest-induced luminescence change (GI), presenting their applications in the detection of nucleic acids, proteins, amino acids, dopamine, and other small molecule biomarkers. In addition, the current challenges of MOFs-based fluorescent biosensors are also discussed, and their further development prospects are concerned.

Confinement of Organic Dyes in UiO-66-Type Metal-Organic Frameworks for the Enhanced Synthesis of [1,2,5]Thiadiazole[3,4-g]benzoimidazoles

Organic dyes as non-noble metal photosensitizers have attracted increasing attention due to their environmental friendliness and sustainability but suffer from fast deactivation and low stability. Here, we reported a fruitful strategy by the confinement and stabilization of visible light-active signal unit organic dyes within the metal-organic frameworks (MOFs) and developed a series of heterogeneous photocatalysts dye@UiO-66s [dye = fluorescein (FL)/rhodamine B (RhB)/eosin Y (EY), UiO-66s = UiO-66, and Bim-UiO-66]. It has been demonstrated that the encapsulated dyes can effectively sensitize MOF hosts and dominate the band structures and photocatalytic activities of dye@UiO-66s regardless of the ligand functionalization of MOFs. Photocatalytic experiments showed that these dye@UiO-66s exhibit enhanced activities relative to free dyes and among them, FL@Bim-UiO-66 displays excellent efficiencies toward the green synthesis of new carbon-bridged annulations, [1,2,5]thiadiazole[3,4-g]benzoimidazoles in the yield of up to 98% at room temperature with outstanding stability and reusability. Furthermore, the intramolecular cyclization intermediate was captured and characterized by the single-crystal X-ray diffraction analysis.

Surface-decorated porphyrinic zirconium-based metal-organic frameworks (MOFs) using post-synthetic self-assembly for photodegradation of methyl orange dye

We report herein the surface decoration of a water-soluble free-base porphyrin, namely, 5,10,15,20-tetrakis(1-methyl-4-pyridinio)porphyrin-tetra(p-toluenesulfonate) (H₂TMPyP), over three different zirconium-based metal-organic frameworks of different linker structure and functionality; namely UiO66, UiO66-NH₂, and MIP-202, via self-assembly. The synthesized MOFs along with the resulting complexes have been characterized via spectroscopic and analytical techniques (XRD, FT-IR, TEM, N₂ adsorption/desorption, and laser scanning confocal microscopy). The self-assembly of H₂TMPyP with the examined three MOFs was observed by using the steady-state absorption and fluorescence, as well as the fluorescence lifetime studies. It was evident that the highest complex interaction was recorded between porphyrin and UiO-66-NH₂ compared with the lowest interactions between porphyrin and MIP-202. This is in good agreement with the high surface area and pore volume of UiO-66 (1100 m² g^-1 and 0.68 cm³ g^-1) and compared to that of MIP-202 (94 m² g^-1 and 0.26 cm³ g^-1). The photocatalytic activities of the three porphyrin entities immobilized zirconium-based MOFs were compared toward methyl orange dye degradation from aqueous solution under visible light irradiation (λ_ex = 430 nm). The photocatalytic studies render the fabrication of the self-assembled H₂TMPyP@UiO-66-NH₂ composite as a promising material for dye degradation from polluted wastewater.

Bionic electroluminescent perovskite light-emitting device

A perovskite light-emitting-diode (PeLED) displaying green color is combined with a brown fluorescent coating (FC) layer to form a hybrid FC-PeLED system. The FC-PeLED system can simulate the natural process of bionics of plant colors from green to brown through a low energy (<0.6 mW) input, promoting the development of future low-cost and low-power consumption bionics technology.

Anionic Regulation toward Bi3+ Selective Occupation for Full-Spectrum White Light Emission

An activator's selective occupation of a host is of great significance for designing high-quality white light-emitting diode phosphors, while achieving a full-spectrum single-phase white light emission phosphor is challenging. In this study, a boron phosphate solid-solution Na₂Y₂(BO₃)_2-x(PO₄)_xO:0.005 Bi³⁺ (NYB_2-xP_xO:0.005 Bi³⁺) white phosphor was designed by selectively occupying Bi³⁺ activators in the mixed anionic groups. The substitutes of the anionic unit (BO₃)^3- by the (PO₄)^3- unit are supposed to force part of the Bi³⁺ ion to enter the Na lattice site, which produces an intense orange-red emission peaked at 590 nm. In parallel, spectral tuning from blue to white light and an internal quantum efficiency of 56.42% was obtained, and the thermal stabile luminescence intensity remains at 94.2% of the initial intensity after four heating-cooling cycles from 30 to 210 °C (luminescent intensity is 83.6% of room temperature (RT) at 150 °C, with excellent thermal stability and recovery performance). Finally, an excellent color rendering index (Ra = 90.8 and R9 = 85) was demonstrated for white light-emitting diode devices using only an NYB_1.5P_0.5O:0.005 Bi³⁺ phosphor and a near-ultraviolet (n-UV) 365 nm LED chip. This work delves into the different selective occupancy of Bi³⁺ ions and explores a new avenue for the design of phosphors for full-spectrum white light emission.

Enhanced Luminescence of Dye-Decorated ZIF-8 Composite Films via Controllable D-A Interactions for White Light Emission

Metal-organic frameworks (MOFs) constructed by metal ions/clusters and organic linkers are used to encapsulate fluorescent guest species with aggregation-caused quenching (ACQ) effects to enhance fluorescence properties due to their porous structures and high specific surface areas. However, there would be a problem of matching between MOF pores and guest molecules' sizes. In this paper, amorphous ZIF-8 was modified by carboxyl functional groups (H₃BTC-ZIF-8) via introducing the 1,2,4-benzenetricarbonic acid (H₃BTC) ligand into the ZIF-8 sol system. Moreover, H₃BTC-ZIF-8 was used for the loading of organic fluorescent dyes rhodamine 6G (R6G) and coumarin 151 (C151) to prepare R6G/C151/H₃BTC-ZIF-8 composite films. A white-light-emitting composite film (R6G/C151/H₃BTC-ZIF-8) with CIE coordinates of (0.323, 0.347) was successfully prepared by compounding fluorescent dyes (R6G and C151) with H₃BTC-modified ZIF-8, whose photoluminescence quantum yield (PLQY) can reach 64.0%. It was higher than the PLQY of the composite films prepared by crystalline ZIF-8 (40.2%) or amorphous ZIF-8 without H₃BTC (48.0%) compounded with the same concentrations of dyes. The fluorescence enhancement was probably attributed to an increased amount of active sites of H₃BTC-modified ZIF-8 interacting with dyes C151 and R6G. This can form hydrogen bonds between H₃BTC-ZIF-8 and C151, and weak electron donor-acceptor (D-A) interactions between H₃BTC-ZIF-8 and R6G molecules, respectively, thus enhancing the interactions between dyes and ZIF-8 and reducing the ACQ effect existing between dye molecules. Therefore, this strategy could provide an important guidance to develop white-light-emissive materials.

A Cerium Organic Framework with {Cu2I2} Cluster and {Cu2I2}n Chain Modules: Structure and Fluorescence Sensing Properties

In this work, a copper iodine module bearing a coordination polymer (CP) with a formula of [(Cu₂I₂)₂Ce₂(INA)₆(DMF)₃]·DMF (1, HINA = isonicotinic acid, DMF = N,N'-dimethyl formamide) is presented. The title compound features a three dimensional (3D) structure, in which the {Cu₂I₂} cluster and {Cu₂I₂}_n chain modules are coordinated by N atoms from a pyridine ring in INA^- ligands, while the Ce³⁺ ions are bridged by the carboxylic groups of INA^- ligands. More importantly, compound 1 exhibits an uncommon red fluorescence (FL) with a single emission band maximized at 650 nm belonging to near infrared (NIR) luminescence. The temperature dependent FL measurement was applied to investigate the FL mechanism. Remarkably, 1 could be used as a FL sensor to cysteine and the nitro-bearing explosive molecule of trinitropheno (TNP) with high sensitivity, demonstrating its potential FL sensing applications for biothiol and explosive molecules.

Dye-Encapsulated Metal-Organic Frameworks for the Multi-Parameter Detection of Temperature

Temperature is an important physical parameter and plays a significant role in scientific research, the detection of which cannot be too crucial to study. In order to reduce the interference of the external environment on the detection of temperature and improve the accuracy of the detection results, a multi-parameter detection method using several optical signals was proposed. Here, a novel porous metal-organic framework (MOF), Zn-CYMPN, was synthesized and structurally characterized. Then, fluorescent organic dyes, either DPEE or DPEM, were encapsulated into the pores of Zn-CYMPN independently. The successful synthesis of the composites Zn-CYMPN&sup;DPEE or Zn-CYMPN&sup;DPEM could easily introduce other fluorescent centers into the original material and made it more convenient to realize multi-parameter temperature detection. More specifically, when the temperature changed, the maximum fluorescent emission wavelength (W) and the maximum optical intensity (I) of the Zn-CYMPN&sup;DPEE/DPEM both showed good linear responses with temperature over a wide range, indicating that the composites were highly sensitive thermometers with multi-parameter temperature readouts. In addition, the quantum efficiency and thermal stability of the organic dyes, which bother every researcher, were improved as well.

Encapsulating Organic Dyes in Metal-Organic Frameworks for Color-Tunable and High-Efficiency White-Light-Emitting Properties

The design of white-light phosphor is highly desirable for practical applications in SSL (solid-state lighting) and its related fields. Dye-loaded metal-organic frameworks (MOFs) have been widely demonstrated as one type of promising down conversion materials for WLEDs (white-light-emitting diodes), but two issues (dye leakage and inadequate quantum efficiency) require to be addressed before possible applications. Here, a series of single-phase dyes@In-MOF phosphors have been prepared in two different ways: the in-situ process and soaking method. The study of these dyes@In-MOF phosphors confirms the importance of this in-situ process that could effectively increase dye loading and quantum efficiency and greatly decrease dye leakage. As a result, a perfect WLED, fabricated using the in-situ-synthesized (AF/RhB@In-MOF)-3 (AF: Acriflavine; RhB: Rhodamine B) and 450 nm blue LED chip, exhibited a very high quantum yield (QY, up to 42.27%), a high luminous efficacy (LE) of 50.75 lm/W, a high color rendering index (CRI) of 91.2, and nearly identical Commission International ed'Eclairage (CIE) coordinates (0.33,0.31), indicating the potential application of the dye-loaded MOFs with good color quality in smart white LEDs.

Ionic metal-organic frameworks (iMOFs): progress and prospects as ionic functional materials

Metal-organic frameworks (MOFs) have been a research hotspot for the last two decades, witnessing an extraordinary upsurge across various domains in materials chemistry. Ionic MOFs (both anionic and cationic MOFs) have emerged as next-generation ionic functional materials and are an important subclass of MOFs owing to their ability to generate strong electrostatic interactions between their charged framework and guest molecules. Furthermore, the presence of extra-framework counter-ions in their confined nanospaces can serve as additional functionality in these materials, which endows them a significant advantage in specific host-guest interactions and ion-exchange-based applications. In the present review, we summarize the progress and future prospects of iMOFs both in terms of fundamental developments and potential applications. Furthermore, the design principles of ionic MOFs and their state-of-the-art ion exchange performances are discussed in detail and the future perspectives of these promising ionic materials are proposed.

Carbazole-Equipped Metal-Organic Framework for Stability, Photocatalysis, and Fluorescence Detection

The useful yet underutilized backfolded design is invoked here for functionalizing porous solids with the versatile carbazole function. Specifically, we attach carbazole groups as backfolded side arms onto the backbone of a linear dicarboxyl linker molecule. The bulky carbazole side arms point away from the carboxyl links and do not disrupt the Zr-carboxyl framework formation; namely, the resultant MOF solid ZrL1 features the same net as that of the unfunctionalized dicarboxyl linker, also known as the PCN-111 net or UiO-66 net. The ZrL1 structure features only half linker occupancy (about 6 out of the 12 linkers around the Zr₆O₈ cluster being missing) and partially collapses upon activation (acetone exchange and evacuation). Notably, the stability improves after heating in diphenyl oxide at 260 °C (POP-260 treatment; to form ZrL1-260), as indicated by the higher crystallinity and surface area of the activated ZrL1-260 sample. The ZrL1-260 samples achieve 72% yield in photocatalyzing reductive dehalogenation of phenacyl bromide; ZrL1 can detect nitro-aromatic compounds via fluorescence quenching, with selectivity and sensitivity toward 4-nitroaniline, featuring a limit of detection of 96 ppb.

Tunable fluorescence emission based on multi-layered MOF-on-MOF

Luminescent metal-organic frameworks (MOFs) have garnered considerable attention in various fields. Herein, we proposed a hierarchical confinement strategy based on MOF-on-MOF to tune luminescence emission ranging from blue to red including white light in a flexible way. The easily available ZIF-8 MOF was used as a host for the confinement of two kinds of size-matching dyes (perylene and rhodamine B) to obtain a layered ZIF-8@dye@ZIF-8@dye via in situ encapsulation and seed-mediated synthesis. ZIF-8@dye@ZIF-8@dye materials with different fluorescence emission in dispersed and solid states were both obtained by tuning the initial encapsulation concentration of dye and changing the structure of the inner and outer ZIF-8@dye layers. To our delight, ZIF-8@0.125perylene@ZIF-8@25RhB with white light emission in the dispersed state was obtained; meanwhile, ZIF-8@0.125perylene + 25RhB and mechanically mixed ZIF-8@0.125perylene + ZIF-8@25RhB could not realize white light emission under the same conditions, indicating that the proposed hierarchical confinement strategy facilitated white light regulation. Similarly, the emission of ZIF-8@dye@ZIF-8@dye in the solid state has also been investigated; ZIF-8@perylene@ZIF-8@3RhB with white light emission was obtained, while white light emission could not be achieved in ZIF-8@perylene + 3RhB and ZIF-8@perylene + ZIF-8@3RhB, which further indicated the importance of the hierarchical confinement strategy based on MOF-on-MOF. The proposed hierarchical confinement strategy may also inspire the development of other functional optical MOF materials.

Confinement of Luminescent Guests in Metal–Organic Frameworks: Understanding Pathways from Synthesis and Multimodal Characterization to Potential Applications of LG@MOF Systems

This review gives an authoritative, critical, and accessible overview of an emergent class of fluorescent materials termed “LG@MOF”, engineered from the nanoscale confinement of luminescent guests (LG) in a metal–organic framework (MOF) host, realizing a myriad of unconventional materials with fascinating photophysical and photochemical properties. We begin by summarizing the synthetic methodologies and design guidelines for representative LG@MOF systems, where the major types of fluorescent guest encompass organic dyes, metal ions, metal complexes, metal nanoclusters, quantum dots, and hybrid perovskites. Subsequently, we discuss the methods for characterizing the resultant guest–host structures, guest loading, photophysical properties, and review local-scale techniques recently employed to elucidate guest positions. A special emphasis is paid to the pros and cons of the various methods in the context of LG@MOF. In the following section, we provide a brief tutorial on the basic guest–host phenomena, focusing on the excited state events and nanoscale confinement effects underpinning the exceptional behavior of LG@MOF systems. The review finally culminates in the most striking applications of LG@MOF materials, particularly the “turn-on” type fluorochromic chemo- and mechano-sensors, noninvasive thermometry and optical pH sensors, electroluminescence, and innovative security devices. This review offers a comprehensive coverage of general interest to the multidisciplinary materials community to stimulate frontier research in the vibrant sector of light-emitting MOF composite systems.

Construction of Large-Scale Conjugated Functionalized Cyclotriphosphazene Lanthanide Framework for Selective Sensing of Volatile Organic Compounds and Assembly of Color-Tunable Dye-Encapsulated Composites

A flexible functionalized cyclotriphosphazene hexacarboxylic acid, hexakis(4-carboxylatephenoxy) cyclotriphosphazene (HCPCP), is used for the synthesis of a family of fluorescent Ln-HCPCP frameworks (Ln = La, Pr, Nd, Gd, and Ho). Structural analysis shows that the compounds exhibit 3D structures with [Ln₃(COO)₁₀], secondary building units formed by Ln-O-C-O-Ln connection. Then the molecules are connected to each other through HCPCP, forming rectangular channels along the c-direction. Interestingly, the fluorescence sensing studies show that compound 1 could be used as a multifunctional fluorescence sensor toward volatile organic compounds via different fluorescence emission behaviors. Moreover, a series of Dye@La-HCPCP composites (Dye = rhodamine B, safranine T, crystal violet, and malachite green) are successfully prepared with different quantum yields by the solvothermal reaction followed by cation exchanges.

Tunable emission of Li4SrCaSi2O4-yN2y/3: Eu2+ phosphors based on anion substitution induction for WLEDs and optical thermometry

Polychromatic emission can be achieved by controlling the distribution of rare earth activator in multi-cation lattices, which can be used in the fields of white light LED and fluorescent temperature...

Biological luminescent metal-organic framework with high fluorescence quantum yield for the selective detection of amino acids and monosaccharides

The biological luminescent metal-organic framework (bio-LMOF), (Me2NH2)2[Zn6O(Ade)4(TCPPE)2] (1) {H4TCPPE = tetrakis[4-(4-carboxyphenyl)phenyl]ethene, Ade = adenine} was successfully designed and synthesized under hydrothermal condition, with two channels of different sizes. The absolute...

Encapsulation of Dyes in Luminescent Metal-Organic Frameworks for White Light Emitting Diodes

The development of white light emitting diodes (WLEDs) holds great promise for replacing traditional lighting devices due to high efficiency, low energy consumption and long lifetime. Metal-organic frameworks (MOFs) with a wide range of luminescent behaviors are ideal candidates to produce white light emission in the phosphor-converted WLEDs. Encapsulation of emissive organic dyes is a simple way to obtain luminescent MOFs. In this review, we summarize the recent progress on the design and constructions of dye encapsulated luminescent MOFs phosphors. Different strategies are highlighted where white light emitting phosphors were obtained by combining fluorescent dyes with metal ions and linkers.

Dual-functional porous MOFs with hierarchical guest encapsulation for room-temperature phosphorescence and white-light-emission

The development of optical materials with room temperature phosphorescence (RTP) and white light emission (WLEDs) is highly desirable and remains a challenging task. Herein, a porous metal-organic framework PCN-921 with a high quantum yield (Φ_F = 93.6%) was achieved. To make full use of the advantages of the high porosity of PCN-921, we hierarchically encapsulated different guest molecules coronene and rhodamine B (RhB) into the framework. Unsurprisingly, the hybrid material coronene@PCN-921 was obtained after in situ encapsulation of the guest coronene into the framework, and it exhibits obvious RTP behavior with a long phosphorescence lifetime of 62.5 ns. Subsequently, second guest RhB molecules were introduced after soaking in RhB solution and the material RhB@coronene@PCN-921 was achieved. Interestingly, it exhibits white light emission with the CIE coordinates of (0.29, 0.34), and can be used as a high performance WLED lamp. This is the first work on dual-functional hybrid dyes@MOFs with hierarchical guest encapsulation for RTP and white light emission, which suggests the potential applications of MOFs in multifunctional optical devices.

Dye encapsulation engineering in a tetraphenylethylene-based MOF for tunable white-light emission

The development of efficient and stable white-light emissive materials is highly desirable in displays and solid-state lighting. Here we present a high-quality white-light emitter based a dual-emitting MOF hybrid, which is achieved by dye encapsulation engineering within a robust Zr-MOF (PCN-128W) containing a highly luminescent tetraphenylethylene-based ligand. The pore confinement effect well isolates the incorporated dye molecules (trans-4-[4-(Dimethylamino)styryl]-1-methylpyridinium iodide (DSM)) and therefore suppress the aggregation caused luminescence quenching. The dye emission is mainly sensitized by PCN-128W host through Förster resonance energy transfer (FRET), and the FRET process is incomplete, thus enabling the hybrid to feature dual emissions upon a single excitation. The emission color of DSM@PCN-128W hybrid can be systematically tuned from blue to white, and to orange by regulating the dye encapsulation content. A broad white-light emission with a considerably high quantum yield (21.2%) is obtained in the case of dye contents of 0.15 wt%. The luminescence of DSM@PCN-128W hybrid is stable in ambient air for over 1 month, and show good resistance to continuous UV light irradiation, owing to the protective MOF Matrix that largely inhibits the UV exposure to dye molecules. What's more, by combining DSM@PCN-128W with a commercial UV LED chip, we fabricate a white-light emitting prototype device showing CIE chromaticity coordinates of (0.34, 0.33), a CRI of 79.1, and a CCT of 5525 K.

Novel perylene probe-encapsulated metal-organic framework nanocomposites for ratiometric fluorescence detection of ATP

Adenosine triphosphate (ATP) plays an important role in various biological processes and the ATP level is closely associated with many diseases. Herein, a novel ratiometric fluorescence assay for ATP was developed based on the excimer-monomer transfer of a perylene probe. By encapsulating a perylene probe, N,N'-bis(6-caproic acid)-3,4:9,10-perylenediimide (PDI), into zeolitic imidazolate framework-8 (ZIF-8) nanocrystals, fluorescent nanocomposites (PDI@ZIF-8) with significant excimer emission of the perylene probe were prepared for the first time. The presence of ATP will trigger the decomposition of PDI@ZIF-8 due to much stronger coordination between ATP and Zn2+ than that of 2-methylimidazole and Zn2+. As a result, the encapsulated PDI probes were released, leading to significantly increased monomer emission accompanying the decrease in the excimer emission. The excimer-monomer transition signal was utilized for ratiometric ATP sensing and its potential application for detecting ATP in cell lysates was also successfully demonstrated.

Dual-emitting piezofluorochromic dye@MOF for white-light generation

An tetraphenylethylene-based MOF (HNU-49) has been synthesized, which exhibits interesting piezofluorochromic behavior. Additionally, rhodamine B (RhB) can be successful encapsulated in HNU-49, to emit the characteristic dual-emission of RhB and the framework. The combination of host-guest interaction and piezofluorochromism can precisely modulate the luminescence to achieve near white-light.

Efficient Regulation of Energy Transfer in a Multicomponent Dye-Loaded MOF for White-Light Emission Tuning

Owing to their rich porosity and structural diversity, metal-organic frameworks (MOFs) offer substantial advantages over other emission sources for the precise design and color regulation of white-light phosphors. However, achieving efficient white-light emission remains a considerable challenge. Herein, we report a strategy to achieve tunable and efficient white-light emission by regulating energy transfer in a multicomponent dye-loaded MOF. An anionic MOF NKU-114 featuring appropriate confined spaces is designed as a host to deliberately encapsulate three red-, green-, and blue-emissive dyes with adaptive spectral overlap, DSM, AF, and 9-AA, respectively, yielding the NKU-114@dyes composites. Integrating the suitable spectral overlap and efficient energy transfer between the dyes and the framework produced a white-light emission material containing the multicomponent dyes NKU-114@DSM/AF/9-AA. The obtained material has a broadband white emission with a high quantum yield (up to 42.07%) and nearly identical CIE coordinates of (0.34, 0.32), and the moderate correlated color temperature and color-rendering index value can reach up to 5101 K and 81, respectively, suggesting the potential of the multicomponent dye-loaded MOF for white-light-emitting phosphors with good color quality.

A lanthanide–organic crystalline framework material encapsulating 1,3,6,8-tetrakis(p-benzoic acid)pyrene: selective sensing of Fe3+, Cr2O72−and colchicine and white-light emission

A facile strategy was used to construct a series of composite materials with color-tunable and white light emission by encapsulating 1,3,6,8-tetrakis(p-benzoic acid)pyrene (H₄TBAPy) into framework material [Eu(MCTCA)_1.5(H₂O)₂]·1.75H₂O.

Three Models To Encapsulate Multicomponent Dyes into Nanocrystal Pores: A New Strategy for Generating High-Quality White Light

Highly luminescent metal-organic frameworks (LMOFs) have received great attention for their potential use in energy-efficient general lighting devices such as white-light-emitting diodes (WLEDs); however, achieving strong emission with controllable color, especially high-quality white light, remains a considerable challenge. Herein, we present a new strategy to encapsulate in situ multiple dyes into nanocrystalline ZIF-8 pores to form an efficient dyes@MOF system. Using this strategy, we build three models, namely, multiphase single-shell dye@ZIF-8, single-phase single-shell dyes@ZIF-8, and single-phase multishell dyes@ZIF-8, to systematically and fine-tune the white emission color by varying the components and concentration of encapsulated dyes. The study of these three models demonstrates the importance of the multishell structure, which can effectively reduce the interactions such as Förster resonance energy transfer (FRET) between encapsulated dyes. This energy transfer would otherwise be unavoidable in a single-shell setting, which often reduces the efficiency of white-light emission in the dyes@MOF system. This approach offers a new perspective not only for fine-tuning the emission color within nanoporous dyes@MOFs but also for fabricating MOF nanocrystals that are easily solution-processable. The strategy may also facilitate the development of other types of MOF-guest nanocomposite systems.

Synthesis and Luminescence Properties of CsPbX3@Uio-67 Composites toward Stable Photoluminescence Convertors

All-inorganic halide perovskite (CsPbX₃, X = Cl, Br, or I) nanocrystals (NCs) have been widely studied due to their outstanding optoelectronic properties. However, some inevitable factors like light, heat, and moisture affected the stability of CsPbX₃ NCs and further limited their practical application. In this work, the stability of all-inorganic halide perovskite NCs can be improved by integrating them in the stable Zr-based metal-organic frameworks (Uio-67). Compared to pristine perovskite NCs, typical CsPbBr₃@Uio-67 composites display a stable photoluminescence property that can be maintained for 30 days under ambient atmospheric conditions. Due to the proposed confinement effects of CsPbX₃ NCs coordinated with the pore structures of Uio-67, the related structural model of CsPbX₃@Uio-67 composites was elucidated. White LED device was further fabricated by combining CsPbBr₃@Uio-67 composites and commercial K₂SiF₆:Mn⁴⁺ red phosphors with a blue-emitting chip, which demonstrated a wide color gamut (138% of National Television Standards Committee color space). The strategy on encapsulation of CsPbX₃ NCs into Uio-67 will open up a stable platform for optoelectronic applications.

A carbazole-functionalized metal–organic framework for efficient detection of antibiotics, pesticides and nitroaromatic compounds

A carbazole-functionalized Cd-MOF exhibits highly selective and sensitive fluorescence detection towards antibiotics, pesticides and nitroaromatic compounds.

Fabrication of a dual-emitting dye-encapsulated metal–organic framework as a stable fluorescent sensor for metal ion detection

The encapsulation of fluorescein dye into porous zinc–adenine metal–organic framework (bio-MOF-1) crystals has been studied for metal cation sensing.

Encapsulation of yellow phosphors into nanocrystalline metal–organic frameworks for blue-excitable white light emission

Anin situsynthesis strategy is developed to encapsulate blue-excitable yellow emitting dyes into metal–organic frameworks to generate white light.