Visible detection of copper ions using a fluorescent probe based on red carbon dots and zirconium metal-organic frameworks.
TL;DR: In practice, the LC emission of UiO-66-(COOH)2 becomes weaker with increasing concentration of Cu2+, whereas the red fluorescence of R-BF-CQDs increases slightly, which provides the possibility of spectral energy transfer.
Abstract: A highly selective and sensitive ratiometric fluorescent probe for copper ions (Cu2+) in aqueous solution based on a blue zirconium metal-organic framework [UiO-66-(COOH)2] with red bandgap fluorescent carbon quantum dots (R-BF-CQDs) is developed. UiO-66-(COOH)2 displays broad ligand-centered (LC) emission and R-BF-CQDs shows red emission. Interestingly, the remaining -NH2 at the surface of the prepared R-BF-CQDs can coordinate Cu2+ efficiently and produce a strong visible absorption, which overlaps the emission of UiO-66-(COOH)2. There is also a strong coordination capacity of the Cu2+ ions with R-BF-CQDs and UiO-66-(COOH)2, which allows the energy donor and the energy receptor to be closer together. Both of these two conditions provide the possibility of spectral energy transfer. In practice, the LC emission of UiO-66-(COOH)2 becomes weaker with increasing concentration of Cu2+, whereas the red fluorescence of R-BF-CQDs increases slightly.
Citations
More filters
TL;DR: In this article, the design tactics of MOFs-based RF sensing and describes the detection mechanism of different RF sensors are described and summarized and prospected, based on different strategies of synthesis, the MRF-based sensors are categorized into three classes: intrinsic dual-emission, single-emissive MOFs with a chromophore and non-EMissive MRF with two chromophores.
211 citations
TL;DR: In this paper, the authors reviewed the encapsulation of various luminescent guests such as lanthanide ions, dyes, quantum dots, and luminescence complexes in metal-organic frameworks to construct luminous sensors with single- or double-emission centers.
Abstract: Metal-organic frameworks (MOFs), which are a class of coordination polymers constructed by metal ions or clusters with organic ligands, have emerged as exciting inorganic-organic hybrid materials with the superiorities of inherent crystallinity, adjustable pore size, clear structure, and high degree of functionalization The MOFs have attracted much attention to develop good luminescent functional materials due to their inherent luminescent centers of both inorganic and organic photonic units Furthermore, the pores within MOFs can also be used to encapsulate a large number of luminescent guest species, which provides a broader luminescent property for MOF materials MOFs possess the incomparable multifunctional advantages of inorganic and organic luminescent materials A large number of luminescent MOFs (LMOFs) have been synthesized for applications in sensing, white-light-emitting diodes (LED), photocatalysis, biomedicine, etc This paper reviews the encapsulation of various luminescent guests such as lanthanide ions, dyes, quantum dots, and luminescent complexes in metal-organic frameworks to construct luminous sensors with single- or double-emission centers, as well as the research progress of these sensors in chemical sensing Finally, the challenges in these fields were outlined and the prospects for future development were put forward
137 citations
TL;DR: This comprehensive review systematically summarizes the luminescence response mode and chemical sensing mechanism for lanthanide-functionalized MOF hybrids (abbreviated as LnFMOFH).
Abstract: The luminescence response application in chemical sensing by metal–organic frameworks (MOFs) and their hybrid materials has been reported extensively in recent years. However, the reviews on this topic are mainly focused on the sensing materials (MOFs and their functionalized hybrid materials) and analytes (all types of species). In this comprehensive review, the luminescence response mode and chemical sensing mechanism for lanthanide-functionalized MOF hybrids (abbreviated as LnFMOFH) are systematically summarized. Specifically, ten sections are subdivided, and importantly involve three main topics. Firstly, LnFMOFH and the luminescence responsive chemical sensing for these hybrids are introduced. Secondly, three single luminescence response modes, including “Turn-Off”, “Turn-On” “Turn–Off–On” and dual mode, as ratiometric luminescence (RL) for chemical sensing in LnFMOFH materials are summarized. Thirdly, some types of chemical sensing mechanisms observed in LnFMOFH materials are outlined, which involve the ligand–metal energy transfer (LMET) for the luminescence response in chemical sensing of enhanced or weakened analytes; the fluorescence (Forster) resonance energy transfer (FRET) and photo-induced electronic transfer (PET) mechanism depending on the energy match between the probe and analyte; and some special chemical interactions for their luminescence response upon chemical sensing, such as hydrogen bonding interaction, coordination interaction and other reactions. Finally, the conclusion and prospects are given for this topic. It needs to be noted that pure lanthanide MOFs (lanthanide ions as the framework metal, including mixed lanthanide MOFs) are not the topic of this review and are only mentioned for background knowledge. Herein, LnFMOFH materials in which the lanthanide ions behave only as photoactive species to functionalize MOF units via post-synthetic modification (PSM) by researchers are the emphasis of this review.
131 citations
TL;DR: The outstanding performance of Ti3C2 MXene based quantum dots has demonstrated their great potential to be used as promising fluorescent probes in the fields of biological imaging, optical sensing, photoelectric conversion, etc.
Abstract: Quantum dots, derived from two-dimensional (2D) materials, have shown promise in bioimaging, sensing and photothermal applications, and in white light emitting devices (WLEDs). Herein, nitrogen and phosphorus functionalized Ti3C2 MXene based quantum dots (N,P-MQDs) were successfully prepared through a top-bottom hydrothermal method. This type of photoluminescent quantum dots has realized green fluorescence for the first time at around 560 nm with a photoluminescence quantum yield (PLQY) of 20.1%, the highest ever reported; meanwhile, it also exhibits excellent photostability and pH resistance capacities. Comprehensive characterization and well-resolved density functional theory (DFT) calculation were implemented to determine the mechanism of fluorescence shift and enhancement. Furthermore, the N,P-MQDs have been proved to efficiently act as fluorescent probes for macrophage labeling. In addition, the high sensitivity of the N,P-MQDs toward Cu2+ ions made them a low cost, sensitive, environment-friendly, and label-free fluorescence platform for Cu2+ detection. The outstanding performance of Ti3C2 MXene based quantum dots has demonstrated their great potential to be used as promising fluorescent probes in the fields of biological imaging, optical sensing, photoelectric conversion, etc.
116 citations
TL;DR: In this paper, a review of recent progress in the rational design and synthesis of carbon dots@metal-organic frameworks (CD@MOF) sensors and their applications in sensing of metal ions, nitroaromatic compounds, water and humidity, temperature, biomarkers, and drugs is presented.
Abstract: As promising sensory materials, metal–organic frameworks have been extensively studied; however, the development of fluorescent MOFs relies heavily on the complex organic ligands and lanthanide metal ions, which remains a challenge. To overcome this barrier, carbon dots@metal–organic frameworks (CD@MOF) have been proposed and developed. CD@MOF composites are newly emerging as fluorescent sensors due to their ease of synthesis, high selectivity and sensitivity to analytes. CD@MOF sensors combine the advantages of both CDs and MOFs, including excellent optical properties of CDs (such as tunable emission lights and photochemical stability) and high surface areas, tunable porosity, and designable functionalities of MOFs, resulting in enhanced sensing performance. This review focuses on recent progresses in the rational design and synthesis of CD@MOF sensors and their applications in sensing of metal ions, nitroaromatic compounds, water and humidity, temperature, biomarkers, and drugs. We also briefly discuss the present challenges and future research directions for CD@MOF sensors.
65 citations
References
More filters
TL;DR: This critical review starts with a brief introduction to gas separation and purification based on selective adsorption, followed by a review of gas selective adsorbents in rigid and flexible MOFs, and primary relationships between adsorptive properties and framework features are analyzed.
Abstract: Adsorptive separation is very important in industry. Generally, the process uses porous solid materials such as zeolites, activated carbons, or silica gels as adsorbents. With an ever increasing need for a more efficient, energy-saving, and environmentally benign procedure for gas separation, adsorbents with tailored structures and tunable surface properties must be found. Metal–organic frameworks (MOFs), constructed by metal-containing nodes connected by organic bridges, are such a new type of porous materials. They are promising candidates as adsorbents for gas separations due to their large surface areas, adjustable pore sizes and controllable properties, as well as acceptable thermal stability. This critical review starts with a brief introduction to gas separation and purification based on selective adsorption, followed by a review of gas selective adsorption in rigid and flexible MOFs. Based on possible mechanisms, selective adsorptions observed in MOFs are classified, and primary relationships between adsorption properties and framework features are analyzed. As a specific example of tailor-made MOFs, mesh-adjustable molecular sieves are emphasized and the underlying working mechanism elucidated. In addition to the experimental aspect, theoretical investigations from adsorption equilibrium to diffusion dynamics via molecular simulations are also briefly reviewed. Furthermore, gas separations in MOFs, including the molecular sieving effect, kinetic separation, the quantum sieving effect for H2/D2 separation, and MOF-based membranes are also summarized (227 references).
7,186 citations
TL;DR: A critical review of the emerging field of MOF-based catalysis is presented and examples of catalysis by homogeneous catalysts incorporated as framework struts or cavity modifiers are presented.
Abstract: A critical review of the emerging field of MOF-based catalysis is presented. Discussed are examples of: (a) opportunistic catalysis with metal nodes, (b) designed catalysis with framework nodes, (c) catalysis by homogeneous catalysts incorporated as framework struts, (d) catalysis by MOF-encapsulated molecular species, (e) catalysis by metal-free organic struts or cavity modifiers, and (f) catalysis by MOF-encapsulated clusters (66 references).
7,010 citations
5,393 citations
4,930 citations
TL;DR: This critical review discusses the origins of MOF luminosity, which include the linker, the coordinated metal ions, antenna effects, excimer and exciplex formation, and guest molecules.
Abstract: Metal–organic frameworks (MOFs) display a wide range of luminescent behaviors resulting from the multifaceted nature of their structure. In this critical review we discuss the origins of MOF luminosity, which include the linker, the coordinated metal ions, antenna effects, excimer and exciplex formation, and guest molecules. The literature describing these effects is comprehensively surveyed, including a categorization of each report according to the type of luminescence observed. Finally, we discuss potential applications of luminescent MOFs. This review will be of interest to researchers and synthetic chemists attempting to design luminescent MOFs, and those engaged in the extension of MOFs to applications such as chemical, biological, and radiation detection, medical imaging, and electro-optical devices (141 references).
4,407 citations