Synthesis of Fluorescent Pyrazoline Sensors as Versatile Tool for Zinc ion Detection: A Mini-Review

Zinc ions are one of the 2nd most abundant mineral after iron and it is important for immune system, enzymatic catalysis, DNA synthesis, and maintaining structural integrity in humans. But, monitoring the Zn levels in human body poses more challenges. This review paper investigates (paper from 2010 to 2023) the synthesis of pyrazoline derivatives by different methods, including conventional methods and green chemistry protocol. These Pyrazoline derivatives highlighted for their potential application as chemo-sensor for Zn2+ ions recognition. Pyrazoline compounds exhibit excellent sensitivity & selectivity and emitting blue-light with high quantum yields and electroluminescence, along with a superior limit of detection. These derivatives are stable bioactive molecule, with well-known diverse biological activities. This review not only gives valuable insights into the essential role of Zinc in human physiology but also provides a practical method for accurate Zinc detection in various samples. Which holds the potential for advancements in health diagnostics and environmental monitoring. Because of their significant biological application and selectivity as sensors, researchers have much more attention to prepare green environmentally-friendly pyrazoline derivatives.

Dual channel ion imprinted fluorescent polymers for dual mode simultaneous chromium speciation analysis

A simple core shell structured fluorescent sensor was constructed to realize simultaneous detection of hexavalent and trivalent chromium ions. Briefly, blue-carbon dots (b-CDs) were embedded into a silica sphere, then a Cr(iii) imprinted silica layer doped with red-CDs (r-CDs) was coated onto the b-CDs@SiO₂. Cr(vi) can selectively quench b-CDs based on the inner filter effect and Cr(iii) can selectively quench r-CDs based on electron transfer with the aid of the ion imprinting technique. In this strategy, it was not necessary to reduce Cr(vi) to Cr(iii) or oxidize Cr(iii) to Cr(vi), the chromium speciation of both can be detected simultaneously. When Cr(vi) was detected in the blue channel, the fluorescence intensity quenching effect was seen at 440 nm, and was linear from 0.01 to 10.0 μM, with a detection limit of 3.8 nM. For the detection of Cr(iii) in the red channel, the fluorescence intensity quenching effect was seen at 605 nm, and was linear from 0.1 to 15.0 μM, with a detection limit of 46 nM. This strategy enjoyed the advantages of simple construction, convenient detection, good selectivity and high sensitivity.

One Pot Generation of Blue and Red Carbon Dots in One Binary Solvent System for Dual Channel Detection of Cr3+ and Pb2+ Based on Ion Imprinted Fluorescence Polymers

Blue and red dual channel dual emission carbon dots (DDCDs) were synthesized by a one-step hydrothermal method in water-formamide binary system using citric acid and ethylenediamine as precursors. Then, the as-prepared DDCDs were directly employed for preparation of ion imprinted fluorescence polymers without further separation. Since Cr³⁺ can only quench the fluorescence of blue CDs, while Pb²⁺ only quenches the fluorescence of red CDs, dual channel detection of Cr³⁺ and Pb²⁺ can be achieved simultaneously based on ion imprinted fluorescence polymers. Under optimized conditions, the quenching effect [(F₀ - F)/F₀] at 440 nm for the blue channel against the concentration of Cr³⁺ was linear from 0.1 to 6.0 μM, while that for the red channel at 580 nm against the concentration of Pb²⁺ was linear from 0.1 to 5.0 μM. The detection limits for Cr³⁺ and Pb²⁺ can reach 27 nM and 34 nM, respectively. Satisfied recoveries have also been obtained for detection of Cr³⁺ and Pb²⁺ in real water samples. The application of this dual channel detection method will greatly simplify the heavy metal ion detection process in complicated water environments.