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The potential emergence of fluorescence‐based techniques has propelled research towards developing probes that can sense trace metal ions specifically. Although luminescent metal‐organic frameworks (MOFs) are well suited for this application, the role of building blocks towards detection is not fully understood. In this work, a systematic screening by varying number of Lewis basic (pyridyl‐N atoms) sites is carried out in a series of isostructural, robust UiO‐67 MOFs, and targeting a model metal ion‐Fe3+. All the three fluorescent MOFs are seen to present quenching response towards Fe3+ ions in water. However, UiO‐67@N exhibits highly selective and sensitive response, whereas emission of both UiO‐67 and UiO‐67@NN is quenched by several metal ions. Detailed experimental and theoretical mechanistic investigation is carried out in addition to demonstration of UiO‐67@N being able to sense trace amount of Fe3+ ions in synthetic biological water sample. Further, UiO‐67@N based mixed‐matrix membrane (MMM) has been prepared and employed to mimic the real time Fe3+ ions detection in water. [ABSTRACT FROM AUTHOR]

Owing to detrimental impact of cyanide ion (CN−) towards the entire living system as well as its availability in drinking water, it has become very important developing potential sensory materials for the selective and sensitive recognition of CN− ions in water. In the domain of sensory materials, luminescent metal‐organic frameworks (LMOFs) have been considered as a promising candidate owing to their unique host‐guest interaction, where MOFs can serve as an ideal scaffold for encapsulating relevant guest molecules rendering specific functionality. In this study, a post‐synthetically modified MOF (viz. CuCl2@MOF‐867) was applied to recognize cyanide (CN−) ions in water via "turn‐on" response. The bipyridyl functionalities in MOF‐867 were used to perform post‐synthetic metalation to infiltrate CuCl2 inside porous architecture of the MOF. Moreover, a CuCl2@MOF‐867 based probe demonstrated highly selective and sensitive aqueous phase recognition of CN− ions even in the presence of other interfering anions such as Br−, NO3−, I−, SO42−, OAc−, SCN−, NO2−, etc. The selective binding of CN− ions to the copper‐metal center has led to the generation of stable Cu(CN)2 species. This phenomenon has further resulted in a fluorescence turn‐on response. The aqueous phase cyanide detection by the rationally modified MOF system exhibited very low limit of detection (0.19 μM), which meets the standardized limit stated by World Health Organization (WHO) that is 1.9 μM. [ABSTRACT FROM AUTHOR]

Neutral nitrogen donor (N‐donor) ligand‐based MOFs, with their enticing features inclusive of facile synthesis, labile metal‐ligand bond, framework flexibility, atomic level tunability renders them appealing in molecular recognition‐based studies. Intriguingly, the flexibility in such systems (owing to weaker metal‐nitrogen bonds) promote maximization of host‐analyte interactions, which is critical for the manifestation of a signaling response. Such host‐analyte interactions can be tapped by discerning any change in the physical properties associated with the system, such as optical, fluorometric, chemiresistive, magnetic, dielectric constant, mass. This minireview presents a brief discussion on the various types of signal transduction pathways unveiled hitherto using neutral N‐donor ligand‐based MOFs and the fundamental insight into the signal's origin. Moreover, an elaborate compilation of the recent examples in this field has been presented. Also, the untapped prospects have been highlighted, which may serve as a beacon to drive future research. [ABSTRACT FROM AUTHOR]

Water pollution and crisis of freshwater is one of the most alarming concern globally, which threatens the development and survival of living beings. Recycling of contaminated water has been the prime demand of 21st century as the area of contamination in natural waterbodies increasing rapidly worldwide. Detoxification and purification of wastewater via adsorptive removal technology has been proven to be more efficient because of it's simplicity, lesser complexity and cost‐effectiveness. As the most rapid‐growing division of coordination chemistry, porous coordination polymers (PCPs) or metal−organic frameworks (MOFs) with the liberty of crafting tailorable porous architecture and presence of numerous functional sites have become quintessential for recognition and sequestration of water pollutants. This personal account intends to highlight our recent contributions in the field of sensing and sequestration of toxic aquatic inorganic pollutants by functionalized water stable MOFs. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) have evolved as an exciting class of materials in the domain of porous materials. The unique features of these materials arise from the combined properties of metal ions/clusters and organic struts which form the building blocks of these fascinating architectures. Among other multifarious applications, MOFs have shown tremendous applications as sensory materials for a wide variety of species. The signal transduction induced mechanism in these confined nanospaces generate optical output in response to a particular analyte which can be detected by wide variety of detection techniques. Fluorometric methods of sensing is one of widely studied method over past few decades. MOF‐based fluorometric detection is a key research theme developed over the past few years. In this review, we give a brief overview of the recent developments of MOFs as "turn‐on" sensors for a wide range of analytes (viz. cations, anions, volatile organic compounds (VOCs), etc.). [ABSTRACT FROM AUTHOR]

Abstract: Metal‐organic frameworks (MOFs) have experienced a tremendous growth during last few decades as porous crystalline molecular materials. The comprehensive effect of structural diversity, tunability and high surface area makes MOFs suitable for multifarious applications. MOFs can act as potential receptors toward different target components along with ionic species, small molecules, solvents, explosives etc. Anion recognition remains an important phenomena due to its involvement in many chemical and biological processes. Ligand designing, incorporation of appropriate functional groups and post‐synthetic modifications are key strategies in MOFs for selective recognition and scavenging of environmentally toxic and detrimental anions (i. e. cyanide, oxo‐anions etc.). The main focus of this personal account is on our research towards development and potential applications of MOFs with special emphasis on selective and sensitive anion sensing. [ABSTRACT FROM AUTHOR]

A porous covalent triazine framework (CTF) consisting of both an electron-deficient central triazine core and electron-rich aromatic building blocks is reported. Taking advantage of the dual nature of the pore surface, bimodal functionality has been achieved. The electron deficiency in the central core has been utilized to address one of the pertinent problems in chemical industries, namely separation of benzene from its cyclic saturated congener, that is, cyclohexane. Also, by virtue of the electron-rich aromatic rings with Lewis basic sites, aqueous-phase chemical sensing of a nitroaromatic compound of highly explosive nature (2,4,6-trinitrophenol; TNP) has been achieved. The present compound supersedes the performance of previously reported COFs in both the aspects. Notably, this reports the first example of pore-surface engineering leading to bimodal functionality in CTFs. [ABSTRACT FROM AUTHOR]

Keywords: iron metal ions; metal-organic frameworks; metal ions; sensing; selective detection EN iron metal ions metal-organic frameworks metal ions sensing selective detection 1 1 1 04/14/22 20220412 NES 220412 B The role of the organic building units b of MOFs towards selective detection of a targeted metal cation (Fe SP 3+ sp ) has been demonstrated by systematic screening by varying the number of Lewis basic (pyridyl-N atoms) sites in a series of isostructural metal-organic frameworks (MOFs). Iron metal ions, metal-organic frameworks, metal ions, sensing, selective detection. [Extracted from the article]

Cover Feature: Selective and Sensitive Fluorescence Turn-On Detection of Cyanide Ions in Water by Post Metallization of a MOF (ChemPlusChem 1/2022) Cyanide ion, fluorescence, metal-organic framework, selective recognition, sensing Keywords: cyanide ion; fluorescence; metal-organic framework; selective recognition; sensing EN cyanide ion fluorescence metal-organic framework selective recognition sensing 1 1 1 02/01/22 20220101 NES 220101 B The Cover Feature shows b a potential sensory material (CuCl SB 2 sb @MOF-867), which has been developed by post metallization (CuCl SB 2 sb ) of a water stable luminescent metal-organic framework, namely MOF-867, constructed with bipyridyl functionality as organic linker. [Extracted from the article]

Keywords: Luminescence; Metal-organic frameworks; Porous coordination polymers; Sensing; Turn-on sensors The practical usability in terms of stability and performance make MOFs a stand-out class of materials for turn-on fluorescent sensing. Luminescence, Metal-organic frameworks, Porous coordination polymers, Sensing, Turn-on sensors. [Extracted from the article]

Graphical abstract A post-synthetically modified MOF has been employed for sensing of bisulfite anion in water medium. This MOF based selective turn on response towards bisulfite anion has also been demonstrated in presence of concurrent anions. Abstract A metal–organic framework (MOF) based luminescent probe was strategically designed for selective recognition of bisulfite anion (HSO 3 −) in water medium. The chemically stable MOF, NH 2 -MIL-68(In) was decorated with specific recognition site via post synthetic modification. The post synthetically modified MOF showed a selective turn on response towards bisulfite anion retaining its structural integrity. This selective recognition is also persistent even in presence of competing anions. [ABSTRACT FROM AUTHOR]

A pyridyl-functionalized metal-organic framework (namely, UiO-66@N) has been employed for the selective and sensitive detection of Fe3+ ions. A pyridyl-functionalized metal-organic framework (namely, UiO-66@N) with excellent chemical stability has been employed as a fluorescent sensor for the selective and sensitive detection of Fe3+ ion. UiO-66@N has been found to maintain its superior fluorogenic selectivity for Fe3+ ion over the other competitive metal ions. The uncoordinated nitrogen atoms-rich porous surface of UiO-66@N has been noticed to act as a Lewis basic probe for selective recognition of Fe3+ ion. In addition, UiO-66@N has shown its potential to detect Fe3+ ion even in the presence of other concurrent analytes. Furthermore, low limit of detection and high quenching constant of the UiO-66@N has verified the efficiency of the probe as a sensor of Fe3+ ion. [ABSTRACT FROM AUTHOR]