Solvothermal Synthesis of High-Performance d10-MOFs with Hydrogel Membranes @ "Turn-On" Monitoring of Formaldehyde in Solution and Vapor Phase

Recent and emerging trends of metal-organic frameworks (MOFs)-based sensors for detecting food contaminants: A critical and comprehensive review

Interest in the use of sensors based on metal-organic frameworks (MOFs) to detect food pollutants has been growing recently due to the desirable characteristics of MOFs, including uniform structures, large surface area, ultrahigh porosity and easy-to-functionalize surface. Fundamentally, this review offers an excellent solution using MOFs-based sensors (e.g., fluorescent, electrochemical, electrochemiluminescence, surface-enhanced Raman spectroscopy, and colorimetric sensors) to detect food contaminants such as pesticide residues, mycotoxins, antibiotics, food additives, and other hazardous candidates. More importantly, their application scenarios and advantages in food detection are also introduced in more detail. Therefore, this systematic review analyzes detection limits, linear ranges, the role of functionalities, and immobilized nanoparticles utilized in preparing MOFs-based sensors. Additionally, the main limitations of each sensing type, along with the enhancement mechanisms of MOFs in addressing efficient sensing are discussed. Finally, the limitations and potential trends of MOFs-based materials in food contaminant detection are also highlighted.

Conformational Switch of a Peptide Provides a Novel Strategy to Design Peptide Loaded Porous Organic Polymer for Pyroptosis Pathway Mediated Cancer Therapy

While peptide-based drug development is extensively explored, this strategy has limitations due to rapid excretion from the body (or shorter half-life in the body) and vulnerability to protease-mediated degradation. To overcome these limitations, a novel strategy for the development of a peptide-based anticancer agent is introduced, utilizing the conformation switch property of a chameleon sequence stretch (PEP1) derived from a mycobacterium secretory protein, MPT63. The selected peptide is then loaded into a new porous organic polymer (PG-DFC-POP) synthesized using phloroglucinol and a cresol derivative via a condensation reaction to deliver the peptide selectively to cancer cells. Utilizing ensemble and single-molecule approaches, this peptide undergoes a transition from a disordered to an alpha-helical conformation, triggered by the acidic environment within cancer cells that is demonstrated. This adopted alpha-helical conformation resulted in the formation of proteolysis-resistant oligomers, which showed efficient membrane pore-forming activity selectively for negatively charged phospholipids accumulated in cancer cell membranes. The experimental results demonstrated that the peptide-loaded PG-DFC-POP-PEP1 exhibited significant cytotoxicity in cancer cells, leading to cell death through the Pyroptosis pathway, which is established by monitoring numerous associated events starting from lysosome membrane damage to GSDMD-induced cell membrane demolition. This novel conformational switch-based drug design strategy is believed to have great potential in endogenous environment-responsive cancer therapy and the development of future drug candidates to mitigate cancers.

A sensitive fluorometric-colorimetric dual-mode intelligent sensing platform for the detection of formaldehyde

Excess formaldehyde (FA) is a strong carcinogen, so the development of a rapid visualized and portable formaldehyde detection platform is of great research importance. A multi-color fluorescence sensing system constituted of model compound (NAHN) and red-emitting InP/ZnS QDs was constructed herein, which can simultaneously realize fluorometric-colorimetric dual-mode sensing when exposed to FA environment. Its preparation process was simplified, the detection process was green, and the limits of detection (LOD) were 0.623 μM and 0.791 μM, respectively. The high recoveries of FA in actual water samples indicated that the sensor had broad application prospects. The prepared fluorescent film can be utilized for rapid visual simulation analysis of FA on the surface of various fruits and vegetables. In addition, a serial logic gate was designed to quickly semi-quantitatively assess FA concentration, which promoted the realization of on-site intelligent evaluation of FA.

Proposals for gas-detection improvement of the FeMPc monolayer towards ethylene and formaldehyde by using bimetallic synergy

Development and fabrication of a novel gas sensor with superb performance are crucial for enabling real-time monitoring of ethylene (C2H4) and formaldehyde (H2CO) emissions from industrial manufacture. Herein, first-principles calculations and AIMD simulations were carried out to investigate the effect of the Fe-M dimer on the adsorption of C2H4 and H2CO on metal dimer phthalocyanine (FeMPc, M = Ti-Zn) monolayers, and the electronic structures and sensing properties of the above adsorption systems were systematically discussed. The results show that the FeMPc (M = Ti, V, Cr, Mn) monolayers interact with C2H4 and H2CO by chemisorption except for the FeMnPc/H2CO system, while the other adsorption systems are all characterized by physisorption. Interestingly, the adsorption strength of C2H4 and H2CO can be effectively regulated by the bimetallic synergy of the Fe-M dimer. Moreover, the FeCrPc and FeMnPc monolayers exhibit excellent sensitivity towards C2H4 and H2CO, and have short recovery time (4.69 ms-2.31 s) for these gases at room temperature due to the effective surface diffusion at 300 K. Consequently, the FeCrPc and FeMnPc materials can be utilized as high-performance, reusable gas sensors for detecting C2H4 and H2CO, and have promising applications in monitoring the release of ethylene and formaldehyde from industrial processes.

Sensing of hyperprolinemia biomarker and its recognition in biological sample through "turn-on" event by Zn-based metal-organic framework

A hydrogen bonded ability metal organic framework (MOF, 1Zn) is used for the ultra-sensitive "turn-on" detection of hyperprolinemia biomarker with ultrafast (within 5 s) colorimetric response making the first MOF based hyperprolinemia biomarker sensor. The detection limit (4.46 ppb) is outperformed compared to all contemporary hyperprolinemia biomarker based sensors. Further, the sensor showed the recognition of biomarker in biological sample (human saliva). The detection of biomarker is also realized through colorimetric response (solution based and paper strip method). The mechanism of sensing is established through the electron transfer and the absorption caused emission (ACE). Moreover, the theoretical study is performed to support the sensing mechanism. The control titration of 1Zn suggest that the free -NH2 group of linker in 1Zn is involved in supramolecular interaction (hydrogen bonding) with the carboxylic group present on biomarker results the facile occurrence of electron transfer and ACE. Consequently, the luminescence "turn-on" effect of 1Zn for hyperprolinemia biomarker is observed.

Two-mode sensing strategies based on tunable cobalt metal organic framework active sites to detect Hg2

Heavy metal pollution poses a major threat to human health, and developing a user-deliverable heavy metal detection strategy remains a major challenge. In this work, two-mode Hg2+ sensing platforms based on the tunable cobalt metal-organic framework (Co-MOF) active site strategy are constructed, including a colorimetric, and an electrochemical assay using a personal glucose meter (PGM) as the terminal device. Specifically, thymine (T), a single, adaptable nucleotide, is chosen to replace typical T-rich DNA aptamers. The catalytic sites of Co-MOF are tuned competitively by the specific binding of T-Hg2+-T, and different signal output platforms are developed based on the different enzyme-like activities of Co-MOF. DFT calculations are utilized to analyze the interaction mechanism between T and Co-MOF with defect structure. Notably, the two-mode sensing platforms exhibit outstanding detection performance, with LOD values as low as 0.5 nM (colorimetric) and 3.69 nM (PGM), respectively, superior to recently reported nanozyme-based Hg2+ sensors. In real samples of tap water and lake water, this approach demonstrates an effective recovery rate and outstanding selectivity. Surprisingly, the method is potentially versatile and, by exchanging out T-Hg2+-T, can also detect Ag+. This simple, portable, and user-friendly Hg2+ detection approach shows plenty of promise for application in the future.

Novel multifunctional environmentally friendly degradable zeolitic imidazolate frameworks@poly (γ-glutamic acid) hydrogel with efficient dye adsorption function

Recently, metal-organic frameworks (MOFs) have been widely developed due to the rich porosity, excellent framework structure and multifunctional nature. Meanwhile, a series of MOFs crystals and MOF-based composites have been emerged. However, the widespread applications of MOFs are hindered by challenges such as rigidity, fragility, solution instability, and processing difficulties. In this study, we addressed these limitations by employing an in-situ green growth approach to prepare a zeolitic imidazolate frameworks-8@poly (γ-glutamic acid) hydrogel (ZIF-8@γ-PGA) with hierarchical structures. This innovative method effectively resolves the inherent issues associated with MOFs. Furthermore, the ZIF-8@γ-PGA hydrogel is utilized for dye adsorption, demonstrating an impressive maximum adsorption capacity of 1130 ± 1 mg/g for methylene blue (MB). The adsorption behavior exhibits an excellent agreement with both the kinetic model and isotherm. Meanwhile, because the adsorbent raw materials are all green non-toxic materials, multiple applications of materials can also be realized. Significantly, the results of antibacterial experiments showed that the ZIF-8@γ-PGA hydrogel after in-situ growth of ZIF-8 had better antibacterial properties. Thus, the ZIF-8@γ-PGA hydrogel has great potential for development in wound dressings, sustained drug owing to its biocompatibility and antibacterial activity.

The impact of environmentally friendly supramolecular coordination polymers as carbon steel corrosion inhibitors in HCl solution: synthesis and characterization

Two 3D-supramolecular coordination polymers (SCP1 & SCP2) have been synthesized and characterized by physicochemical and spectroscopic methods. In a solution of 1.0 M HCl, SCPs were used to prevent corrosion of carbon steel (CS). The inhibition productivity (%η) rises as the synthetic inhibitor dose rises, and the opposite is true as the temperature rises. The study was carried out using chemical (mass loss, ML) and electrochemical ( potentiodynamic polarization, PDP and electrochemical impedance microscopy, EIS) techniques, which showed %η reached to 93.1% and 92.5% for SCP1 & SCP2, respectively at 21 × 10-6 M, 25 °C. For the polarization results, SCPs behave as mixed-type inhibitors. With increasing doses of SCPs, the charge transfer resistance grew and the double layer's capacitance lowered. The creation of a monolayer on the surface of CS was demonstrated by the finding that the adsorption of SCPs on its surface followed the Henry adsorption isotherm. The parameters of thermodynamics were computed and explained. The physical adsorption of SCPs on the surface of CS is shown by the lowering values of free energy (∆Goads < - 20 kJ mol-1) and increasing the activation energy (E*a) values in presence of SCP1 & SCP2 than in their absence. Atomic force microscope (AFM) and scanning electron microscopy (SEM) demonstrated the development of a protective thin film of SCPs precipitated on the surface of CS. There is a strong matching between results obtained from experimental and theoretical studies. Results from each approach that was used were consistent.

Fluorescence sensing and device fabrication with luminescent metal-organic frameworks

Metal-organic frameworks (MOFs) are a novel class of hybrid porous multi-functional materials consisting of metal ions/clusters and organic ligands. MOFs have exclusive benefits due to their tunable structure and diverse properties. Luminescent MOFs (LMOFs) exhibit both porosity and light emission. They display abundant host and guest responses, making them conducive to sensing. Currently, LMOF sensing research is gaining more depth, with attention given to their device and practical applications. This work reviews recent advancements and device applications of LMOFs as chemical sensors toward ions, volatile organic compounds, biomolecules, and environmental toxins. Furthermore, the detection mechanism and the correlation between material properties and structure are elaborated. This analysis serves as a valuable reference for the preparation and efficient application of targeted LMOFs.

Pathways toward wearable and high-performance sensors based on hydrogels: toughening networks and conductive networks

Wearable hydrogel sensors provide a user-friendly option for wearable electronics and align well with the existing manufacturing strategy for connecting and communicating with large numbers of Internet of Things devices. This is attributed to their components and structures, which exhibit exceptional adaptability, scalability, bio-compatibility, and self-healing properties, reminiscent of human skin. This review focuses on the recent research on principal structural elements of wearable hydrogels: toughening networks and conductive networks, highlighting the strategies for enhancing mechanical and electrical properties. Wearable hydrogel sensors are categorized for an extensive exploration of their composition, mechanism, and design approach. This review provides a comprehensive understanding of wearable hydrogels and offers guidance for the design of components and structures in order to develop high-performance wearable hydrogel sensors.

Metal-organic frameworks (MOFs) based luminescent and electrochemical sensors for food contaminant detection

With the increasing population, food toxicity has become a prevalent concern due to the growing contaminants of food products. Therefore, the need for new materials for toxicant detection and food quality monitoring will always be in demand. Metal-organic frameworks (MOFs) based on luminescence and electrochemical sensors with tunable porosity and active surface area are promising materials for food contaminants monitoring. This review summarizes and studies the most recent progress on MOF sensors for detecting food contaminants such as pesticides, antibiotics, toxins, biomolecules, and ionic species. First, with the introduction of MOFs, food contaminants and materials for toxicants detection are discussed. Then the insights into the MOFs as emerging materials for sensing applications with luminescent and electrochemical properties, signal changes, and sensing mechanisms are discussed. Next, recent advances in luminescent and electrochemical MOFs food sensors and their sensitivity, selectivity, and capacities for common food toxicants are summarized. Further, the challenges and outlooks are discussed for providing a new pathway for MOF food contaminant detection tools. Overall, a timely source of information on advanced MOF materials provides materials for next-generation food sensors.

Recent progress of oxidative stress associated biomarker detection

Oxidative stress denotes the imbalance between the generation of reactive oxygen species (ROS) and antioxidant defenses in living organisms, participating in various pathophysiological processes and mediating the occurrence of diseases. Typically, the excessive production of ROS under oxidative stress elicits oxidative modification of biomacromolecules, including lipids, proteins and nucleic acids, leading to cell dysfunction and damage. Therefore, the analysis and detection of oxidative stress-associated biomarkers are of considerable importance to accurately reflect and evaluate the oxidative stress status. This review comprehensively elucidates the recent advances and applications of imaging probes for tracking and detecting oxidative stress-related biomarkers such as lipid peroxidation, and protein and DNA oxidation. The existing challenges and future development directions in this field are also discussed.

Regulating the photophysical properties of ESIPT-based fluorescent probes by functional group substitution: a DFT/TDDFT study

CONTEXT

In recent years, fluorescent probe technology has received more and more attention. However, the photophysical and photochemical properties of probe molecules still need to be further explored. This paper presents the excited state intramolecular proton transfer (ESIPT) processes and photophysical properties of the probe molecule 4-bromo-2-((E)-((Z)-((5-bromo-1H-indol-2-yl) methylene) hydrazono) methyl) phenol (BHPL) and its four derivatives (BHPL2, BHPL3, BHPL4, and BHPL5). Infrared spectra and geometric structure analyses revealed that introducing the -NH₂ group on the benzene ring with the hydroxyl group will enhance the intramolecular hydrogen bond, which benefits the ESIPT process. Combining their absorption and fluorescence spectra, it can be concluded that BHPL2 and BHPL4 are both excellent probe candidates due to their large Stokes shift. The hole and electron and root mean square displacement analyses manifest that the fluorescence quenching of BHPL4 may be due to the intramolecular charge transfer process. Potential energy curves of BHPL and its four derivatives noted that ESIPT process of the BHPL2 is the most favorable to occur. The frontier molecular orbital and NBO analyses indicated that besides introducing electron-donating groups to reduce the energy gap and enhance fluorescence emission, introducing double electron-withdrawing groups can also achieve this effect, explaining why the energy barrier of ESIPT process for BHPL2 is lower than BHPL5. This work would provide the theoretical basis for designing novel fluorescence probes with more prominent properties.

METHODS

The ground (S₀) and excited (S₁) state structures of all compounds were optimized by density functional theory (DFT) and time-dependent (TDDFT) method, with B3LYP/6-311+G(d,p) level, respectively. The infrared spectra and potential energy curves were simulated at the same theoretical level. The reduced density gradient scatter plots and interaction region indicator isosurfaces were drawn using Multiwfn and VMD programs. The absorption and fluorescence spectra were simulated by the TDDFT/B3PW91/6-311+G(d,p) method. All the calculations in this work are carried out in Gaussian 16 program package.

Water-Stable Cd-MOF with fluorescent sensing of Tetracycline, Pyrimethanil, abamectin benzoate and construction of logic gate

Due to the indiscriminate abuse of pesticides and antibiotics has caused serious threats to the environment and human and animal bodies, the detection of antibiotics and pesticides has attracted widespread attention in recent years. Herein, a novel 2D Cd (II)-MOF, [Cd(L)_0.5(1,2-bimb)] (Cd-L-1,2-bimb), [H₄L = 1, 1'-ethylbiphenyl -3, 3', 5, 5'- tetracarboxylic acid, 1, 2-bimb = 1, 2-bis[(1H-imidazol-1-yl) methyl] benzene] is synthesized. Cd-L-1,2-bimb has excellent stability in different organic solvents and in the range of pH 1.1-12.5. Cd-L-1,2-bimb exhibits high selectivity, high sensitivity, and fast luminescent response to pesticides [pyrimethanil (PTH, LOD = 2.2 μM) and abamectin benzoate (AMB, LOD = 2.39 μM)] and antibiotic contaminants tetracycline (TET, LOD = 0.13 μM). Cd-L-1,2-bimb displays discriminative fluorescence when detecting AMB and PTH, and is an implication logic gate. Finally, the possible detection mechanism of Cd-L-1,2-bimb toward different pollutants is also further investigated. This MOF-based multifunctional sensor opens up new prospects for environmental monitors.

Recent advances in determination applications of emerging films based on nanomaterials

Sensitive and facile detection of analytes is crucial in various fields such as agriculture production, food safety, clinical diagnosis and therapy, and environmental monitoring. However, the synergy of complicated sample pretreatment and detection is an urgent challenge. By integrating the inherent porosity, processability and flexibility of films and the diversified merits of nanomaterials, nanomaterial-based films have evolved as preferred candidates to meet the above challenge. Recent years have witnessed the flourishment of films-based detection technologies due to their unique porous structures and integrated physical/chemical merits, which favors the separation/collection and detection of analytes in a rapid, efficient and facile way. In particular, films based on nanomaterials consisting of 0D metal-organic framework particles, 1D nanofibers and carbon nanotubes, and 2D graphene and analogs have drawn increasing attention due to incorporating new properties from nanomaterials. This paper summarizes the progress of the fabrication of emerging films based on nanomaterials and their detection applications in recent five years, focusing on typical electrochemical and optical methods. Some new interesting applications, such as point-of-care testing, wearable devices and detection chips, are proposed and emphasized. This review will provide insights into the integration and processability of films based on nanomaterials, thus stimulate further contributions towards films based on nanomaterials for high-performance analytical-chemistry-related applications.

"Caught in the Act" @ disruption of A-ET-E process in the recognition of F- by a lamellar EuIII-MOF in heterogeneous manner with logic gate construction: From protagonist idea to implementation world

Development of cost-effective and reliable fluoride sensor for assessing water quality of natural water samples is of immense importance in developing countries as they can provide an easy platform for safeguarding human health. These sensors should be as simple as possible to be fabricated locally by layman. In this context, Eu^III-based MOFs provide trustable platform with bright luminescence in the visible region due to their absorbance-energy transfer-emission (A-ET-E) process. Herein the designed synthesis of a 2D porous coordination polymer, Eu@CMERI, has been carried out following a solvothermal reaction route. The compound shows selective "turn-off" sensing of fluoride in heterogeneous manner from purely aqueous phase and other biological matrices with a detection limit of 28.4 ppb and it carries enormous importance for drinking water analysis under internal regulations. Prohibition of A-ET-E cycle of the Eu^III-MOF is proposed to be the prime reason for fluorescence quenching upon interaction with F^-. DFT studies also revealed that lowest △E_HOMO-LUMO and highest chemical potential value (μ) of F^- are the driving forces for selectivity of Eu^III-MOF towards the targeted anion. The high stability of the porous frameworks along with its interesting sensing features, including fast response and wide linear detection range etc. instigated us not to restrict the chemistry of Eu^III-MOFs at protagonist idea rather to explore its application to real-world analysis. Based on the fluorescence signal exhibited by the targeted analyte, an integrated AND-OR logic gate has also been fabricated which depicts its applicability in molecular electronics. In view of the modular design principle of our polymeric probe, the proposed strategy could open a new horizon to construct powerful sensing materials for ultrafast detection of other important pollutants in the domain of supramolecular chemistry in coming days.

Formaldehyde recognition through aminal formation in a luminescent metal-organic framework

Two isostructural pillar-layer MOFs (JNU-105 and JNU-105-(NH2)2) have been successfully synthesized. JNU-105-(NH2)2 exhibits a red-shifted luminescence "turn on" for formaldehyde without the interference from other VOCs and a detection limit of 1.87 ppb. In situ single-crystal transformation studies confirm the aminal formation on the pillar linker, which was attributed to the exclusive luminescence response toward formaldehyde.

Numerical Energy Storage Efficiency of MWCNTs-Propylene Glycol by Inducing Thermal Radiations and Combined Convection Effects in the Constitutive Model

This study examines MWCNTs-PG nanofluid with a uniform dispersion of MWCNTs in PG. It is assumed that both MWCNTs and PG exist thermally in equilibrium and no slip occurs between them. MWCNTs were suspended in PG uniformly and played a significant role. Firstly, the problem is formulated by utilizing empirical correlations, thermophysical attributes, and similarity equations. Then the model is treated numerically along with the coupling of a shooting algorithm. The results against the pertinent flow quantities were plotted and provide a basis for a comprehensive discussion, investigating whether MWCNTs-PG has high thermal storage characteristics under the effects of thermal radiation and combined convection effects. Due to their high energy storage capability, these fluids are reliable for industrial applications.

Knoevenagel condensation triggered synthesis of dual-channel oxene based chemosensor: Discriminative spectrophotometric recognition of F-, CN- and HSO4- with breast cancer cell imaging, real sample analysis and molecular keypad lock applications

A novel oxene based unusual sensory receptor (HyMa) has been synthesized via.Knoevenagel condensation triggered carbon-heteroatom (oxygen) intramolecular bond formation reaction at room temperature for discriminative detection of multi-analytes like HSO₄^-, CN^- & F^- by spectro-photometric alterations with profound selectivity with the detection limit of 38 ppb, 18 ppb & 94 ppb respectively. Examination of the sensing mechanism was exhaustively investigated through several spectroscopic means like ¹H NMR, FT-IR, absorption and fluorescence spectra etc. In addition, quantum mechanical calculations like DFT and Loewdin spin population analyses also validated the rationality of the host-guest interaction. Apart from these, the reversible spectroscopic responses of HyMa towards F^- and Al³⁺ can imitate several complex logic functions that in turn help in preparing molecular keypad lock. This molecular keypad lock has the potential to protect the confidential information at the molecular scale. Additionally, the MTT assay of HyMa showed low cytotoxicity and membrane permeability indicating its attractive capability for bio-imaging towards triple negative breast cancer. HyMa-coated test strips could also be employed towards on-site detection of these deadly contaminants via "Dip Stick" approach without help of any instrumentation. In addition, HyMa has also been exploited for quantitative determination of HSO₄^- from various real water samples. In a nutshell, detection of lethal contaminants like CN^-, F^- & HSO₄^- at ppb level with in vitro live cell imaging has been explored with proper photophysical characterisation and theoretical calculations with real field applications.

A Review on Recent Sensing Methods for Determining Formaldehyde in Agri-Food Chain: A Comparison with the Conventional Analytical Approaches

Formaldehyde, the simplest molecule of the aldehyde group, is a gaseous compound at room temperature and pressure, is colorless, and has a strong, pungent odor. It is soluble in water, ethanol, and diethyl ether and is used in solution or polymerized form. Its maximum daily dosage established by the EPA is 0.2 μg g−1 of body weight whereas that established by the WHO is between 1.5 and 14 mg g−1: it is in category 1A of carcinogens by IARC. From an analytical point of view, formaldehyde is traditionally analyzed by HPLC with UV-Vis detection. Nowadays, the need to analyze this compound quickly and in situ is increasing. This work proposes a critical review of methods for analyzing formaldehyde in food using sensing methods. A search carried out on the Scopus database documented more than 50 papers published in the last 5 years. The increase in interest in the recognition of the presence of formaldehyde in food has occurred in recent years, above all due to an awareness of the damage it can cause to human health. This paper focuses on some new sensors by analyzing their performance and comparing them with various no-sensing methods but focusing on the determination of formaldehyde in food products. The sensors reported are of various types, but they all share a good LOD, good accuracy, and a reduced analysis time. Some of them are also biodegradable and others have a very low cost, many are portable and easy to use, therefore usable for the recognition of food adulterations on site.

Unveiling of a smartphone-mediated ratiometric chemosensor towards the nanomolar level detection of lethal CN-: combined experimental and theoretical validation with the proposition of a molecular logic circuitry

A promising naphthalene-functionalized ratiometric chemosensor (E)-1-((naphthalen-5-yl) methylene)-2-(2,4-dinitrophenyl) hydrazine (DNMH) is unveiled in the present work. DNMH demonstrates brisk discernible colorimetric response from yellow to red in the presence of CN⁻, a lethal environmental contaminant, in a near-perfect aqueous medium with a LOD of 278 nM. The “key role marker” controlling the electrochemical and non-covalent H-bonding interaction between DNMH and CN⁻ is through the commendable role of acidic –NH functionalities. Kinetic studies reveal a pseudo second order reaction rate and the formation of an unprecedented photostable adduct. The negative value of ΔG as evaluated from ITC substantiates the spontaneity of the DNMH⋯CN⁻ interaction. The sensing mechanism was further reinforced with state-of-the-art theoretical investigations, namely DFT, TDDFT and Fukui indices (FIs). Moreover, the proposition of a reversible multi-component logic circuitry implementing Boolean functions in molecular electronics has also been triggered by the turn-over spectrophotometric response of the ditopic ions CN⁻ and Cd²⁺. The cytotoxicity of DNMH towards Bacillus thuringiensis and Escherichia coli is successfully investigated via the MTT assay. Impressively, “dip stick” and “easy to prepare” test paper device and silica gel-based solid-phase CN⁻ recognition validate the on-site analytical application of DNMH. Furthermore, the involvement of a synergistic approach between ‘chemistry beyond the molecule’ and ‘engineering’ via an exquisitely implemented smartphone-assisted colorimetric sensory prototype makes this work unprecedented among its congeners and introduces a new frontier in multitudinous material-based functional product development.

A ratiometric chemosensor (DNMH) is unveiled herein, demonstrating selective chromogenic response towards CN⁻, with a LOD of 278 nM. Consequently, molecular logic circuitry and a smartphone-based colorimetric sensory prototype has been explored.

Highly regenerative, fast colorimetric response for organo-toxin and oxo-anions in an aqueous medium using a discrete luminescent Cd(II) complex in a heterogeneous manner with theoretical revelation

The highly luminescent complex [CdQ₂(H₂O)₂] (1) shows ultra-selectivity and high sensitivity to the explosive organo-toxin trinitrophenol (TNP). This detection is extremely fast with a high quenching constant (5.3 × 10⁴ M^-1) and a very low limit of detection (LOD) of 137 nM/59 ppb. This motivated us to detect the lethal carcinogenic arsenical drug roxarsone (ROX), which is reported here for the first time. The quenching constant and LOD for ROX using 1 were found to be 4.9 × 10⁴ M^-1 and 86 nM (or 37 ppb), respectively. Moreover, the probe also recognizes three lethal toxic oxo-anions (MnO₄^-, Cr₂O₇^2- and CrO₄^2-) with outstanding quenching constant (2.2 × 10⁴ M^-1, 1.4 × 10⁴ M^-1 and 1.1 × 10⁴ M^-1) and very low LODs (141 nM/61 ppb, 178 nM/78 ppb and 219 nM/95 ppb). Compared to the previously reported homogeneous sensing nature of the discrete complexes, our complex showed the detection of toxic pollutants in a heterogeneous manner, which results in high recyclability and hence multi-cycle sensing capability. Interestingly, 1 shows the possibility for real-time monitoring through naked eye detection by visible colorimetric changes in solid, solution and strip paper methods, i.e., triphasic detection ability. In addition, the sensor also exhibited the cross-sensing ability for these pollutants. The experimental sensing mechanism is strongly supported by the exhaustive theoretical investigation. Based on the fluorescence signal shown by each analyte, an integrated AND-OR logic gate is constructed. Furthermore, the sensing ability of 1 remains intact towards the detection of versatile real field samples including lethal carcinogenic arsenical drug roxarsone in the real food sample.

Recent progress on porous MOFs for process-efficient hydrocarbon separation, luminescent sensing, and information encryption

Metal-organic frameworks (MOFs), as an emerging class of porous materials, excel in designability, regulatability, and modifiability in terms of their composition, topology, pore size, and surface chemistry, thus affording a huge potential for addressing environment and energy-related challenges. In particular, MOFs can be applied as porous adsorbents for the purification of industrially important hydrocarbons through certain process-efficient separation schemes based on selectivity-reversed adsorption and multicomponent separation. Moreover, the vast combination possibilities and controllable and engineerable luminescent units of MOFs make them a versatile platform to develop functionally tailored materials for luminescent sensing and optical data encryption. In this feature article, we summarize the recent progress in the use of porous MOFs for the separation and purification of acetylene (C₂H₂) and ethylene (C₂H₄) based on selectivity-reversed adsorption and multicomponent separation strategies. Moreover, we highlight the advances over the past three years in the field of MOF-based luminescent materials for thermometry, turn-on sensing, and information encryption.

2D MOF nanosheets as an artificial light-harvesting system with enhanced photoelectric switching performance

Herein, we report the synthesis, structure and photophysical properties of a novel well-defined layered metal-organic framework (MOF) [Cd(ppda)(mbib)] by the selection of two flexible ligands 1,4-phenylenediacetic acid (ppda) and 1,3-bis(imidazol-1-ylmethyl)benzene...

Highly selective and sensitive fluorescence detection of tetracyclines based on novel tungsten oxide quantum dots

Tetracyclines (TCs) residues in animal products have attracted extensive concern due to their potential toxic to human health. Accordingly, it is urgent to develop an efficient method to determine TCs for providing consumers with risk pre-warning. Herein, a novel tungsten oxide quantum dots (W_xO_y QDs) fluorescence probe for tetracycline (TET) detection was constructed through ethanol-thermal method, which exhibited intense blue fluorescence under 365 nm UV light. Interestingly, blue-emitting W_xO_y QDs could be quenched obviously after the addition of TET, which may be attributed to the synergism of inner filter effect (IFE), fluorescence resonance energy transfer (FRET) and photo-induced electron transfer (PET). Thereby, the fluorescence method was established for TET detection based on W_xO_y QDs. Additionally, the presented method was demonstrated by monitoring TET in milk and milk powder with satisfactory recoveries. More importantly, this work offered good demonstration for the detection of food hazard factors.