An exceptionally stable Zr-based fluorescent metal–organic framework for highly selective detection of pH

Wu, Shuang; Wang, Shu; Fang, Wen-Le; Guo, Xiao‐Feng; Wang, Hong

doi:10.1039/c8ay01998c

Cited by 19 publications

(14 citation statements)

References 39 publications

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“…It was attempted to increase the hydrolytic stability of the MOF in basic media, yet the performance in terms of sensing was not impressive. A similar strategy was utilized by Wang and co-workers 632 who prepared a MOF on the basis of Zr 6 clusters and 2,2′-bipyridine-5,5′-dicarboxylic acid, responsible for the intrinsic pH sensitivity of the material.…”

Section: Materials With Dual Functionality (Indicator and Host)mentioning

confidence: 99%

Optical Sensing and Imaging of pH Values: Spectroscopies, Materials, and Applications

2020

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This is the first comprehensive review on methods and materials for use in optical sensing of pH values and on applications of such sensors. The Review starts with an introduction that contains subsections on the definition of the pH value, a brief look back on optical methods for sensing of pH, on the effects of ionic strength on pH values and p K a values, on the selectivity, sensitivity, precision, dynamic ranges, and temperature dependence of such sensors. Commonly used optical sensing schemes are covered in a next main chapter, with subsections on methods based on absorptiometry, reflectometry, luminescence, refractive index, surface plasmon resonance, photonic crystals, turbidity, mechanical displacement, interferometry, and solvatochromism. This is followed by sections on absorptiometric and luminescent molecular probes for use pH in sensors. Further large sections cover polymeric hosts and supports, and methods for immobilization of indicator dyes. Further and more specific sections summarize the state of the art in materials with dual functionality (indicator and host), nanomaterials, sensors based on upconversion and 2-photon absorption, multiparameter sensors, imaging, and sensors for extreme pH values. A chapter on the many sensing formats has subsections on planar, fiber optic, evanescent wave, refractive index, surface plasmon resonance and holography based sensor designs, and on distributed sensing. Another section summarizes selected applications in areas, such as medicine, biology, oceanography, bioprocess monitoring, corrosion studies, on the use of pH sensors as transducers in biosensors and chemical sensors, and their integration into flow-injection analyzers, microfluidic devices, and lab-on-a-chip systems. An extra section is devoted to current challenges, with subsections on challenges of general nature and those of specific nature. A concluding section gives an outlook on potential future trends and perspectives.

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Section: Materials With Dual Functionality (Indicator and Host)mentioning

confidence: 99%

Optical Sensing and Imaging of pH Values: Spectroscopies, Materials, and Applications

2020

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“…It is especially common in conjugated molecules having cyano or pyridine groups due to the susceptibility of the nitrogen atoms to protonation. − Protonation can cause large changes in the energy gap of many conjugated organic chromophores, often due to extensive electronic delocalization in the excited state. , Fluorescence quenching can also occur upon protonation of molecules that emit via internal charge transfer . However, the properties of crystalline phases exposed to protonating or deprotonating agents have been reported in only few cases, and in the case of luminescent MOFs, only a quenching effect has been observed to date, suggesting potential applications in explosives sensing. − …”

Section: Introductionmentioning

confidence: 99%

“…30,31 Fluorescence quenching can also occur upon protonation of molecules that emit via internal charge transfer. 32 However, the properties of crystalline phases exposed to protonating or deprotonating agents have been reported in only few cases, 25 and in the case of luminescent MOFs, only a quenching effect has been observed to date, 33 suggesting potential applications in explosives sensing. 34−36 In this work, we synthesize a linear aromatic scaffold of the distyrylbenzene class, in which the outer benzenes are replaced by reactive and accessible pyridine groups.…”

Section: ■ Introductionmentioning

confidence: 99%

Metal–Organic Framework with Color-Switching and Strongly Polarized Emission

et al. 2019

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Hybrid fluorescent metal−organic frameworks (MOFs) use long-range intermolecular structural motifs in which the properties of the scaffold molecular system can be designed for specific applications. In this work, we constructed a MOF−chromophore system with a strongly polarized fluorescence and a large emission wavelength shift. To achieve this, we first devised a fluorophore with a linear conjugated backbone, bulky and noninteracting side chains, and easily accessible nitrogen atoms on its pyridine end groups. The linear nature of the conjugated backbone can lead to a strongly polarized luminescence, the side groups assist structural stability and minimize intermolecular interactions, and the sterically accessible pyridines provide a large fluorescence colorchanging ability. These features were demonstrated by synthesizing a planar Zn-based MOF in which the linear backbone of the chromophore molecules was highly aligned. The MOFs demonstrated a strong polarization effect and a color-shifting ability from green-yellow to orange. The results show that hybrid metal−organic materials can be designed to generate a strong command of the material luminescence, in terms of both emission color and polarization.

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“…However, the strong coordinative ability of the N sites with metal ions imposes a limitation on the strategy. An approach to achieve free basic N atoms in MOFs is the utilization of metal ions with a higher affinity for O than for N. Successful examples are some Zr(IV) and Ln(III) MOFs with pyridyl- or porphyrin-containing linkers. ,− Another approach is to use the ligand in which the coordination of N with metal ions is sterically hindered. Some MOFs of this kind have been reported, where the free N atoms are proposed to be conducive to CO 2 adsorption, but the pH sensing properties remain largely unexplored.…”

Section: Introductionmentioning

confidence: 99%

A pH-Sensing Fluorescent Metal–Organic Framework: pH-Triggered Fluorescence Transition and Detection of Mycotoxin

Yang

Liu

et al. 2020

Inorg. Chem.

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Due to its great relevance to environmental, biological, and chemical processes, the precise detection of pH or acidic/basic species is an ongoing and imperative need. In this context, pH-sensitive luminescent systems are highly desired. We reported a three-dimensional Zn(II) MOF synthesized from a bipyridyl-tetracarboxylic ligand and composed of 4-fold interpenetrated diamond frameworks. Because the steric hindrance in the ligand prevents metal coordination with the pyridyl group, the MOF features free basic N sites accessible to the small H + ions, which renders pH responsivity. The aqueous dispersion exhibits an abrupt, high-contrast, and reversible on−off fluorescence transition in the narrow pH range of 5.4−6.2. The sensitive bistable system can be used for the precise monitoring of pH within the range and for use as a pH-triggered optical switch. The responsive mechanism through pyridyl protonation is collaboratively supported by data fitting, absorption spectra, and molecular orbital calculations. In particular, spectral and theoretical analyses reveal the destruction of n → π* transitions and the appearance of intramolecular charge-transfer transitions upon pyridyl protonation. Moreover, by virtue of the pH-responsive fluorescence, the MOF shows appealing sensing performance for the detection of 3-nitropropionic acid, a major mycotoxin in moldy sugar cane.

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An exceptionally stable Zr-based fluorescent metal–organic framework for highly selective detection of pH

Abstract: UiO-67-bpydc was synthesized as pH sensor for specifically sensing pH in bodyfluids matrix, based on the protonation of bipyridine group.

Cited by 19 publications

References 39 publications

Optical Sensing and Imaging of pH Values: Spectroscopies, Materials, and Applications

Optical Sensing and Imaging of pH Values: Spectroscopies, Materials, and Applications

Metal–Organic Framework with Color-Switching and Strongly Polarized Emission

A pH-Sensing Fluorescent Metal–Organic Framework: pH-Triggered Fluorescence Transition and Detection of Mycotoxin

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