Remarkable Vapochromic Behavior of Pure Organic Octahedron Embedded in Porous Frameworks

Unlocking Diabetic Acetone Vapor Detection by A Portable Metal-Organic Framework-Based Turn-On Optical Sensor Device

Despite exhaled human breath having enabled noninvasive diabetes diagnosis, selective acetone vapor detection by fluorescence approach in the diabetic range (1.8-3.5 ppm) remains a long-standing challenge. A set of water-resistant luminescent metal-organic framework (MOF)-based composites have been reported for detecting acetone vapor in the diabetic range with a limit of detection of 200 ppb. The luminescent materials possess the ability to selectively detect acetone vapor from a mixture comprising nitrogen, oxygen, carbon dioxide, water vapor, and alcohol vapor, which are prevalent in exhaled breath. It is noteworthy that this is the first luminescent MOF material capable of selectively detecting acetone vapor in the diabetic range via a turn-on mechanism. The material can be reused within a matter of minutes under ambient conditions. Industrially pertinent electrospun luminescent fibers are likewise fabricated alongside various luminescent films for selective detection of ultratrace quantities of acetone vapor present in the air. Ab initio theoretical calculations combined with in situ synchrotron-based dosing studies uncovered the material's remarkable hypersensitivity toward acetone vapor. Finally, a freshly designed prototype fluorescence-based portable optical sensor is utilized as a proof-of-concept for the rapid detection of acetone vapor within the diabetic range.

High Peroxidase-Mimicking Metal-Organic Frameworks Decorated with Platinum Nanozymes for the Colorimetric Detection of Acetylcholine Chloride and Organophosphorus Pesticides via Enzyme Cascade Reaction

The sensitive detection of acetylcholinesterase (AChE) and organophosphorus pesticides (OPs) is very important for the protection of human health. Herein, a hybrid material, Pt NPs/Fe-MOF, consisting of a metal-organic framework (MIL-88B-NH2, Fe-MOF) decorated with platinum nanoparticles (Pt NPs), was prepared first and exhibited remarkably improved and excellent peroxidase-mimicking activity compared to the Fe-MOF material resulting from the synergistic catalysis effect between Fe-MOF and Pt NPs, which can effectively catalyze 3,3',5,5'-tetramethylbenzidine (TMB) oxidation to generate a blue product (oxidized TMB, oxTMB). Interestingly, in the presence of AChE and acetylcholinesterase, the peroxidase-mimicking activity from Pt NPs/Fe-MOF was inhibited obviously, and thus, a colorimetric sensing platform for AChE can be constructed; more importantly, after the addition of OPs, this nanozyme activity can be recovered, inducing the further successful construction of a sensitive colorimetric sensing platform for OPs. The related sensing mechanism and condition optimization were studied, and the as-prepared Pt NPs/Fe-MOF nanozyme-based colorimetric method for AChE and OP detection displayed superior analytical performances with wide linearities and low detection limits. Furthermore, the designed method offers satisfactory real application ability. We expect the as-proposed Pt NPs/Fe-MOF nanozyme-based colorimetric sensing platform for AChE and OPs via the enzyme cascade reaction to show great potential application.

Sensors for Volatile Organic Compounds

This paper provides an overview of recent developments in the field of volatile organic compound (VOC) sensors, which are finding uses in healthcare, safety, environmental monitoring, food and agriculture, oil industry, and other fields. It starts by briefly explaining the basics of VOC sensing and reviewing the currently available and quickly progressing VOC sensing approaches. It then discusses the main trends in materials' design with special attention to nanostructuring and nanohybridization. Emerging sensing materials and strategies are highlighted and their involvement in the different types of sensing technologies is discussed, including optical, electrical, and gravimetric sensors. The review also provides detailed discussions about the main limitations of the field and offers potential solutions. The status of the field and suggestions of promising directions for future development are summarized.

Obvious vapochromic color changes of a pillar[6]arene containing one benzoquinone unit with a mechanochromic change before vapor exposure

We developed a color changeable aromatic vapor detection system by combining the mechanochromism and vapochromism of pillar[6]arene containing one benzoquinone unit. The color of pillar[6]arene solid was changed by mechanochromism before vapor exposure. Different aromatic vapors then induced an obvious vapochromic color change from dark red to light orange or vice versa.

Vapochromic crystals: understanding vapochromism from the perspective of crystal engineering

Vapochromic materials, which undergo colour and/or emission changes upon exposure to certain vapours or gases, have received increasing attention recently because of their wide range of applications in, e.g., chemical sensors, light-emitting diodes, and environmental monitors. Vapochromic crystals, as a specific kind of vapochromic materials, can be investigated from the perspective of crystal engineering to understand the mechanism of vapochromism. Moreover, understanding the vapochromism mechanism will be beneficial to design and prepare task-specific vapochromic crystals as one kind of low-cost 'electronic nose' to detect toxic gases or volatile organic compounds. This review provides important information in a broad scientific context to develop new vapochromic materials, which covers organometallic or coordination complexes and organic crystals, as well as the different mechanisms of the related vapochromic behaviour. In addition, recent examples of supramolecular vapochromic crystals and metal-organic-framework (MOFs) vapochromic crystals are introduced.

Exploring the Place of Animals and Human–Animal Relationships in Hydraulic Fracturing Discourse

Throughout human history, energy security has been a prominent concern. Historically, animals were used as energy providers and as companions and sentinels in mining operations. While animals are seldom used for these purposes in developed communities today, this legacy of use is likely to have far-reaching consequences for how animals and human–animal relationships are acknowledged in energy development. The US is currently experiencing an energy boom in the form of high volume horizontal drilling and hydraulic fracturing (HVHHF); because animals are the most at risk from this boom, this study uses a thorough content analysis of peer-reviewed HVHHF articles mentioning animals from 2012–2018 to assess how animals and human–animal relationships are discussed. Three dominant article theme classifications emerge: animal-focused articles, animal-observant articles, and animal sentinel articles. Across themes, articles seldom acknowledge the inherent value or the social and psychological importance of animals in human lives; instead, the focus is almost exclusively on the use of animals as sentinels for potential human health risks. Further, what is nearly absent from this body of literature is any social science research. Given that relationships with animals are an integral part of human existence, this study applies environmental justice principles, serving as a call to action for social science scholars to address the impacts of HVHHF on animals and human–animal relationships.

Alkane-Shape-Selective Vapochromic Behavior Based on Crystal-State Host-Guest Complexation of Pillar[5]arene Containing One Benzoquinone Unit

Colored crystals of pillar[5]arene containing one benzoquinone unit were found to exhibit alkane-shape-selective vapochromic behavior. Activated pillar[5]arene crystals, prepared by removing solvated methanol from pillar[5]arene crystals, changed color from dark-brown to light-red after exposure to linear alkane vapors; however, no color changes were observed on exposure to branched or cyclic alkanes. Uptake of methanol vapor by the activated crystals induced a different color change, from dark-brown to black. This multi-vapochromism results from the different intermolecular π-stacking interactions between the benzoquinone and 1,4-diethoxybenzene units in the alkane- and methanol-containing crystals. Unlike most known vapochromic materials, these pillar[5]arene-based materials were highly stable; after uptake of n-alkanes or methanol the color of the crystals did not change after storage in air for 3 weeks. This is because the included guests were stabilized in the cavity by multiple CH/π interactions.

Metal–organic frameworks: functional luminescent and photonic materials for sensing applications

This review summarizes the diverse routes to derive sensing applications from suitably functionalized and crystal-engineered metal–organic framework (MOF) materials, either by fluorometric responses, or based on photonic crystal-based signal transduction.

Remarkable colorimetric sensing of heavy metal ions based on thiol-rich nanoframes

Tailored dimercaptosuccinic acid based nanoframes were developed for sensing heavy metal ions, where remarkable colorimetric changes were observed in response to different heavy metal ions. The present work demonstrates a simple and effective approach for the detection of heavy metal ions.