Selective monitoring of Cu(II) with a fluorescence–on naphthalene–based probe in aqueous solution

Luminous Insights: Exploring Organic Fluorescent "Turn-On" Chemosensors for Metal-Ion (Cu+2, Al+3, Zn+2, Fe+3) Detection

There are several metal ions that are vital for the growth of the environmental field as well as for the biological field but only up to the maximum limit. If they are present in excess, it could be hazardous for the human health. With the growing technology, a series of various detection techniques are employed in order to recognize those metal ions, some of them include voltammetry, electrochemical methods, inductively couples, etc. However, these techniques are expensive, time consuming, requires large storage, advanced instrumentation, and a skilled person to operate. So, here comes the need of a sensor and it is defined as a miniature device which detects the substance of interest by giving response in the form of energy change. So, from past few decades, many sensors have been formulated for detecting metal ions with some basic characteristics like selectivity, specificity, sensitivity, high accuracy, lower detection limit, and response time. Detecting various metal ions by employing chemosensors involves different techniques such as fluorescence, phosphorescence, chemiluminescence, electrochemical, and colorimetry. The fluorescence technique has certain advantages over the other techniques. This review mainly focuses on the chemosensors that show a signal in the form of fluorescence to detect Al+3, Zn+2, Cu+2, and Fe+3 ions.

Strategies for Improving Selectivity and Sensitivity of Schiff Base Fluorescent Chemosensors for Toxic and Heavy Metals

Toxic cations, including heavy metals, pose significant environmental and health risks, necessitating the development of reliable detection methods. This review investigates the techniques and approaches used to strengthen the sensitivity and selectivity of Schiff base fluorescent chemosensors designed specifically to detect toxic and heavy metal cations. The paper explores a range of strategies, including functional group variations, structural modifications, and the integration of nanomaterials or auxiliary receptors, to amplify the efficiency of these chemosensors. By improving selectivity towards targeted cations and achieving heightened sensitivity and detection limits, consequently, these strategies contribute to the advancement of accurate and efficient detection methods while increasing the range of end-use applications. The findings discussed in this review offer valuable insights into the potential of leveraging Schiff base fluorescent chemosensors for the accurate and reliable detection and monitoring of heavy metal cations in various fields, including environmental monitoring, biomedical research, and industrial safety.

Synthesis, optical properties, determination and imaging in living cells and bamboo of cinnamaldehyde derivatives

Two Schiff-base fluorescent probes (1 and 2) were directly synthesized from natural cinnamaldehyde, and they were characterized by FT-IR, ¹H and ¹³C NMR, HRMS. Compound 1 had no fluorescence, while compound 2 could emit significant yellow fluorescence in solid and provide green light in solution. Probe 1 could selectively sense ClO^- with a fluorescence enhancement, providing a good linear relationship between the fluoresence intensity and ClO^- concentrations (0-5.5 × 10^-5 mol/L), y = 175.64x-19.399, R² = 0.9937, and the limit of detection (LOD) was 39.4 nM. Probe 2 was sensitive for Cu²⁺ by quenching with two linear relationships at the Cu²⁺ concentrations from 0 to 2.1 × 10^-5 mol/L, LOD = 73.9 nM. Furthermore, live celluar imaging of human astrocytoma U-251 MG cells and human liver cancer cells (Hu-7) had achieved using the 1 + ClO^- and 2, offering clear intracellular fluorescence. Finally, the 1 + ClO^- and 2 could also be used to dye bamboo tissues for a good use. Thus, the cinnamaldehyde derivatives could be further used in the field of celluar and bamboo imaging.