Quinoline-based colorimetric chemosensor for Cu2+: Cu2+-induced deprotonation leading to color change

Colorimetric and Fluorometric N-Acylhydrazone-based Chemosensors for Detection of Single to Multiple Metal Ions: Design Strategies and Analytical Applications

The development of optical sensors for metal ions has gained significant attention due to their broad applications in biology, the environment, and medicine. Colorimetric and fluorometric detection methods are particularly valued for their simplicity, cost-effectiveness, high detection limits, and analytical power. Among various chemical probes, the hydrazone functional group stands out for its extensive study and utility, owing to its ease of synthesis and adaptability. This review provides a comprehensive overview of N-acylhydrazone-based probes, serving as highly effective colorimetric and fluorometric chemosensors for a diverse range of metal ions. Probes are categorized into single-ion, dual-ion, and multi-ion chemosensors, each further classified based on the detected metal(s). Additionally, the review discusses detection modes, detection limits, association constants, and spectroscopic measurements.

Architecture of Easy-to-Synthesize and Superior Probe Based on Aminoquinoline Appended Naphthoquinone: Instant and On-Site Cu2+ Ion Quantification in Real Samples and Unusual Crystal Structure and Logic Gate Operations

Easy-to-synthesize aminoquinoline (AQ) appended naphthoquinone (NQ)-based colorimetric and ratiometric probe (AQNQ) was successfully synthesized in one step with high yield and low cost, and was utilized to supply an effective solution to critical shortcomings encountered in Cu2+ analysis. The structure of AQNQ and its interaction with Cu2+ forming an unusual AQNQ-Cu complex were enlightened with single-crystal X-ray diffraction analysis and different spectroscopic methods. AQNQ-Cu complex is the first Cu2+ containing dinuclear crystal where the octahedral coordination sphere is fulfilled through the coordination of a NQ oxygen atom. AQNQ exhibited long-term stability (more than 1 month), superior probe ability toward Cu2+ with quite fast response (30 s), high selectivity among many ions, and limit of detection of 12.13 ppb that is significantly below the highest amount of Cu2+ allowed in drinking water established by both WHO and EPA. Ratiometric determination of Cu2+ using AQNQ was performed with high recovery and low RSD values for drinking water, tap water, lake water, cherry, and watermelon samples. Colorimetric on-site determination including smartphone and paper strip applications, IMPLICATION, and INHIBIT logic gate applications were successfully carried out. The reversibility and reusability of the response to Cu2+ ions with the paper strip application were examined for the first time.

Movement of new direction from conjugated polymer to semiconductor composite polymer nanofiber

In the past few years, there was a tremendous growth in conjugated polymer nanofibers via design of novel conjugated polymers with inorganic materials. Synthetic routes to these conjugated polymers involve new, mild polymerization techniques, which enable the formation of well-defined polymer architectures. This review provides interest in the development of novel (semi) conducting polymers, which combine both organic and inorganic blocks in one framework. Due to their ability to act as chemosensors or to detect various chemical species in environmental and biological systems, fluorescent conjugated polymers have gained great interest. Nanofibers of metal oxides and sulfides are particularly interesting in both their way of applications and fundamental research. These conjugated nanofibers operated for many applications in organic electronics, optoelectronics, and sensors. Synthesis of electrospun fibers by electrospinning technique discussed in this review is a simple method that forms conjugated polymer nanofibers. This review provides the basics of the technique and its recent advances in the formation of highly conducting and high-mobility polymer fibers towards their adoption in electronic application.

A novel fluorescein-based colorimetric probe for Cu2+ detection

A new colorimetric probe, 5-chlorosalicylaldehyde fluorescein hydrazone (CSFH), has been synthesized and characterized by, FT-IR, NMR, mass elemental analysis and X-ray single crystal diffraction.

A Highly Selective and Sensitive Chemosensor for Colorimetric and Fluorescent Detection of Al3+ and Living Cell Imaging

A colorimetric and fluorescent dual chemosensor for detecting Al3+, (E)-N′-((2-hydroxynaphthalen-1-yl)methylene)nicotinohydrazide (HNN), was developed by combining 2-hydroxy-1-naphthaldehyde with nicotinohydrazide. Addition of Al3+ to EtOH–H2O solution of HNN gives rise to a visible colour change from colourless to light blue and a significantly enhanced fluorescence. Other metal ions including Na+, K+, Ca2+, Mg2+, Mn2+, Co2+, Ni2+, Cu2+, Cr3+, Ag+, Pb2+, Zn2+, Cd2+, Hg2+, Fe2+, and Fe3+ have no or little effect on the specific response of HNN to Al3+. The binding mode of HNN–Al3+ complex was further clarified by electrospray ionisation mass spectrometry and 1H NMR titration experiments.