Detection of Co2+ via fluorescence resonance energy transfer between synthesized nitrogen-doped carbon quantum dots and Rhodamine 6G

From Structure to Sensing: Molecular Mechanistic Insights into Plant-Derived Carbon Dots for Heavy Metal Ion Detection

Plant-derived carbon dots (P-CDs) are gaining attention in environmental remediation due to their cost-effectiveness, availability, and lower toxicity compared with chemically synthesized carbon dots. This review comprehensively examines the recent advancements in the synthesis and application of P-CDs, with a particular emphasis on their efficacy in the sensing of heavy metals, which are among the most pervasive environmental contaminants. A detailed comparative analysis is presented by evaluating the performance of P-CDs against their chemically synthesized counterparts based on key parameters, such as optimal operating conditions and detection limits. Furthermore, sensing the potential of P-CDs towards every heavy metal ion has been discussed with in-depth mechanistic insights. Additionally, this review explores the industrial applications and future directions of P-CDs. This review provides a comprehensive analysis of -P-CDs for heavy metal sensing, aiming to enhance their sensitivity and selectivity toward heavy metal ions.

Reflectance and photophysical properties of rhodamine 6G/2-(4-methyl-2-oxo-2H-chromen-7-yloxy) acetic acid as cold hybrid colorant

Rhodamine 6G (Rh6G) is modified by ethylenediamine to obtain rhodamine with amine functional groups (Rh6G-NH₂). Rh6G-NH₂ as an initial core is used to bond coumarin derivatives. Synthesized fluorescent colorants are specified using Fourier transform infrared spectroscopy (FT-IR), proton and carbon nuclear magnetic resonance (¹H NMR and ¹³C NMR), X-ray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM) to analyze the structure of the fluorescent pigments. Fluorescence microscopy, fluorescence spectrophotometer, and UV–visible–NIR reflectance spectra are used to demonstrate the optical properties. UV–Vis–NIR reflectance spectra showed that synthesized colorants were transparent in NIR region. Also, photophysical properties of 2-(4-methyl-2-oxo-2H-chromen-7-yloxy) acetic acid (MOHCYAA), Rh6G-NH₂, and hybrid 2-(4-methyl-2-oxo-2H-chromen-7-yloxy) acetic acid/rhodamine 6G (HMR) were investigated. Type of solvent had a strong effect on quantum yield. Rh6G-NH₂ (ϕ_s = 0.66) and HMR (ϕ_s = 0.72) displayed the maximum quantum yield in ethanol due to good interaction with ethanol and the formation of ring-opened amide form of rhodamine group. Finally, Rh6G-NH₂ and HMR displayed the maximum quantum yield in ethanol due to good interaction of structure with ethanol and the formation of ring-opened amide form of rhodamine group in compound.

Heavy metal ion detection using green precursor derived carbon dots

The discovery of carbon dots (CDs) for environmental remediation has gained awareness because of the diverse economically viable and environmental friendly green precursors generated from biowastes and biomass compared to the toxic inorganic quantum dots and CDs prepared from chemical precursors. This review presents the recent progress in green CDs, including their synthesis methods and sensing applications for the detection of heavy metal ions such as Iron (III), Mercury (II), Copper (II), Chromium (VI), Lead (II), Arsenic (III), Cobalt (II), Aluminum (III), Silver (I), and Gold (III) which are prominent environmental pollutants. The comparison based on selectivity, sensitivity, quantum yield, detection limit, linear concentration range, and sensing mechanisms are also reported. This review also covers the performance of doped green CDs using heteroatoms, toward the detection of heavy metal ions. Apart from the future perspectives, this review provides a general guide to use such environmental friendly CDs to detect harmful pollutants.