Novel fluorescent probe bearing triarylimidazole and pyridine moieties for the rapid and naked-eye recognition of Cu 2+

A Coumarin-Based Fluorescent Probe for Ratiometric Detection of Cu2+ and Its Application in Bioimaging

The fluorescent probe L, based on naphthalimide-modified coumarin, was designed, synthesized, and characterized, which could recognize Cu2+ from other cations selectively and sensitively in HEPES buffer (10 mM, Ph = 7. 4)/CH3CN (1:4, V/V). When the probe L interacted with Cu2+, the color and the fluorescent intensity changed obviously and it provided the naked-eye detection for Cu2+. The recognition mode between them was achieved by Job's plot, IR, MS, SEM, and 1HNMR. In addition, test strips made from L could still interact with Cu2+ in tap water effectively. The limit of detection (LOD) of L was 3.5 × 10-6 M. Additionally, the density functional theory (DFT) calculation method was used to analyze the action mechanism of L toward Cu2+. Importantly, the fluorescent probe L could demonstrate favorable selectivity toward Cu2+ in Caenorhabditis elegans. Thus, L was considered to have some potential for application in bioimaging.

Structural design of a high sensitivity biomass cellulose-based colorimetric sensor and its in situ visual recognition mechanism for Cu2

A novel biomass cellulose-based colorimetric sensor (DAC-PDH) was prepared by a Schiff base reaction between the aldehyde groups of dialdehyde cellulose (DAC) and the amino groups of 2,6-pyridine dihydrazide (PDH). The as-prepared sensor (DAC-PDH) showed selective recognition of Cu²⁺ and a visual colour change from white to green. The visual limit of detection for Cu²⁺ was 10^-7 mol/L. Furthermore, DAC-PDH responded to Cu²⁺ within 30 s by the method of dynamic condition. The sensor possessed the properties of a high density of functional groups (CO, NH, NH₂), a large external surface area, a short transit distance and flexibility; thus, Cu²⁺ can be rapidly absorbed and enriched on the DAC-PDH through multi-dentate ligand chelation between Cu²⁺ and the carbonyl groups (CO) and the amino groups (NH, NH₂) of DAC-PDH. The as-prepared DAC-PDH colorimetric sensor exhibits promising prospects for in situ identification of Cu²⁺.

Highly selective and sensitive determination of Cu2+ in drink and water samples based on a 1,8-diaminonaphthalene derived fluorescent sensor

A new simple and efficient fluorescent sensor L based on 1,8‑diaminonaphthalene Schiff-base for highly sensitive and selective determination of Cu²⁺ in drink and water has been developed. This Cu²⁺-selective detection over other tested metal ions displayed an obvious color change from blue to colorless easily detected by naked eye. The detection limit is determined to be as low as 13.2 nM and the response time is very fast within 30 s. The 1:1 binding mechanism was well confirmed by fluorescence measurements, IR analysis and DFT calculations. Importantly, this sensor L was employed for quick detection of Cu²⁺ in drink and environmental water samples with satisfactory results, providing a simple, rapid, reliable and feasible Cu²⁺-sensing method.