Selective and Sensitive Fluorescence Turn-On Detection of Cyanide Ions in Water by Post Metallization of a MOF

Selective detection of SO2 in NU-1000 via organometallic nickel silylphosphine post-synthetic complex incorporation

The adsorption and detection of SO2 using Zr-based MOF, NU-1000 grafted with an organometallic nickel silylphosphine complex ([NiSi]@NU-1000) via post-synthetic modification are reported. [NiSi]@NU-1000 exhibits high stability under dry and wet SO2, with a high cyclability performance. Moreover, fluorescence experiments postulate [NiSi]@NU-1000 as a promising SO2 detector due to its high SO2 selectivity over CO2 and air, showing an evident quenching effect, especially at low SO2 concentrations (0.1 bar of SO2). Time-resolved photoluminescence experiments suggest that host-guest SO2 interactions are associated with the turn-off effect.

Cu-TCPP Metal-Organic Nanosheets Embedded Thin-Film Composite Membranes for Enhanced Cyanide Detection and Removal: A Multifunctional Approach to Water Treatment and Environmental Safety

Cyanide is highly toxic, with widespread industrial use posing serious environmental risks. Effective materials for detecting and filtering cyanide from water are urgently needed. This study introduces a novel approach utilizing Cu-TCPP (TCPP = o-tetra(4-carboxyphenyl)porphine) metal-organic nanosheets (MONS) embedded in thin-film composite membranes, offering a multifunctional solution for cyanide detection and filtration. Ultrathin Cu-TCPP MONs were synthesized using a surfactant-assisted method featuring highly accessible metal centers that enhance cyanide interaction and detection. The membranes, developed by modifying cellulose acetate (CA) with Cu-TCPP MONs, demonstrated exceptional performance for cyanide removal. The 6% Cu-TCPP/CA membrane exhibited a 2.3-fold increase in pure water permeability and achieved a cyanide removal efficiency of 94.68%, significantly outperforming the pristine 0% Cu-TCPP/CA membrane (Pure Water Permeability (PWP) = 380.83 L m-2 h-1 bar-1; CN- removal = 5.01%). This is the first report describing the detection and removal of CN- in water using the membrane technique in literature. In addition to its removal efficiency, the Cu-TCPP MONs showed remarkable detection capabilities, with a calculated limit of detection of 1.76 × 10-7 M, surpassing World Health Organization (WHO) and United States Environmental Protection Agency (EPA) safety standards for cyanide levels in water. Additionally, Cu-TCPP MONs, a bioimaging agent with excellent cell viability, were deployed to detect CN- in MiaPaCa-2 cells, detecting concentrations as low as 0.1 ppm.

ICT-based fluorescent nanoparticles for selective cyanide ion detection and quantification in apple seeds

In this report, we successfully engineered a novel probe based on an acceptor-donor-acceptor (A-D-A) architecture featuring dicyanovinyl-substituted thieno[3,2-b]thiophene, termed DCVTT. The designed probe self-assembles into luminous nanoparticles (DCVTT NPs) upon introducing mixed aqueous solutions. These fluorescent nanostructures served as a ratiometric probe for detecting cyanide (CN-) ions in aqueous-based environments, owing to the robust Intramolecular Charge Transfer (ICT) characteristics of DCVTT. The A-D-A substituents in DCVTT significantly enhanced ICT behavior by promoting more efficient electron transfer between the donor and acceptor groups. This improved electron transfer process leads to heightened sensitivity in detection applications. In the case of cyanide (CN) sensing, this enhanced ICT behavior manifests as a strong colorimetric response, allowing for a visible color change before and after interaction with cyanide. Speculation regarding the interaction mechanism between DCVTT and CN- is proposed based on the findings of various experimental analyses. The detection limit (LOD) for DCVTT in identifying CN- is 0.83 nM, significantly lower than the CN- concentration thresholds deemed safe by the World Health Organization (WHO) and the United States Environmental Protection Agency (EPA). Time-Dependent Density Functional Theory (TD-DFT) has been utilized to theoretically analyze the optical properties of DCVTT both before and after the introduction of the CN- ions. A paper-based test strip was developed to demonstrate its practical application to enable efficient qualitative CN- detection by visual inspection. Furthermore, this sensing platform demonstrates highly accurate quantitative detection of CN- in apple seeds. No prior reports have utilized fluorescence techniques to estimate apple seeds' CN levels.

Solid-State Solvent-Independent Excited-State Intramolecular Proton Transfer in a Coordination Polymer and Its Temperature Dependence

Increasing demand for futuristic switches and sensors around the world has created an intense interest in smart materials, which can show a rapid but feature-dependent change in the physical properties in the presence of external stimuli. Hitherto such changes in the photophysical property of materials, specifically in the solid state, are projected for the use of smart on-off switches. Materials having an external-stimuli-responsive change in the photophysical properties like excited-state intramolecular proton transfer (ESIPT) can also be utilized for these purposes. Although the event of solid-state ESIPT is not new in the domain of material chemistry, especially for organic molecules, it was never observed for coordination polymers (CPs). Previous instances of ESIPT in CPs have necessitated the presence of a solvent as a suspension medium, driving a solvent-assisted ESIPT phenomenon. However, the emergence of a solvent-independent ESIPT-enabled CP presents unique advantages. The well-defined periodic arrangement ensures reliable property variations, while the robust coordination bonds between the metal nodes and ligands provide durability in harsh environments. Addressing this gap, we present the first ever solid-state, solvent-free, and solvent-independent ESIPT-active CP. Remarkably, this CP exhibits temperature-dependent ESIPT on-off behavior, demonstrating its potential as a cutting-edge material in the field of smart switches and sensors.