A simple colorimetric and ratiometric fluoride ion probe with large color change

Synthesis of a new camphor-derived carboxylesterase-activated fluorescent probe for sensitive detection of dimethoate residues in agricultural products and its applications in biological systems

In this paper, a camphor-derived enzyme activatable probe CPA was synthesized for detecting dimethoate pesticide. The ester bond of probe CPA could be selectively hydrolyzed and fragmented in the presence of carboxylesterase (CE), which caused a remarkably enhanced green fluorescence signal at 501 nm. Probe CPA could function as an effective fluorescent platform for the sequential detection of dimethoate due to the obvious inhibition effect of dimethoate on the activity of CE. The detection limit of probe CPA to dimethoate was computed to be 0.1104 μg/mL. Even more important, CPA was effectively utilized for quantitative determination of trace dimethoate residues in agricultural products including fresh vegetables and fruits with good accuracy. Furthermore, the probe CPA could realize the detection of dimethoate in living cells and zebrafish. This work is expected to provide a highly sensitive and accurate analytical method for detecting organophosphorus pesticide residues in food samples and biological systems.

TDDFT Study on the ESIPT Properties of 2-(2'-Hydroxyphenyl)-Benzothiazole and Sensing Mechanism of a Derived Fluorescent Probe for Fluoride Ion

The level of fluoride ions (F-) in the human body is closely related to various pathological and physiological states, and the rapid detection of F- is important for studying physiological processes and the early diagnosis of diseases. In this study, the detailed sensing mechanism of a novel high-efficiency probe (PBT) based on 2-(2'-hydroxyphenyl)-benzothiazole derivatives towards F- has been fully investigated based on density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods. F- attacks the O-P bond of PBT to cleavage the dimethylphosphinothionyl group, and the potential products were evaluated by Gibbs free energy and spectroscopic analyses, which ultimately identified the product as HBT-Enol1 with an intramolecular hydrogen bond. Bond parameters, infrared vibrational spectroscopy and charge analysis indicate that the hydrogen bond is enhanced at the excited state (S1), favoring excited state intramolecular proton transfer (ESIPT). The mild energy barrier further evidences the occurrence of ESIPT. Combined with frontier molecular orbital (FMO) analysis, the fluorescence quenching of PBT was attributed to the photoinduced electron transfer (PET) mechanism and the fluorescence turn-on mechanism of the product was attributed to the ESIPT process of HBT-Enol1.

One-dimensional Europium-coordination polymer as luminescent sensor for highly selective and sensitive detection of 2,4,6-trinitrophenol

Three isostructural lanthanide coordination polymers (LnCPs), [Ln(L)₆(DMF)]_n {HL = 2-(2-formylphenoxy) acetic acid, Ln = Sm (1); Eu (2); Tb (3)} have been synthesized by solvothermal reaction and characterized. Single crystal analyses revealed that the architectures of these LnCPs own one dimensional chain which can be further packed into two-dimensional architectures by hydrogen bonds. Moreover, these LnCPs can offer strategically placed uncoordinated formyl groups, which may act as hydrogen-bond acceptor in the sensing of nitro explosives. Luminescence measurements reveal that LnCPs 2 and 3 exhibit strong luminescence in solid states. LnCP 2 shows quick, highly selective and sensitive detection of 2,4,6-trinitrophenol (TNP) with the high quenching constant (2.6 × 10⁴ M^-1) and low detection limit (3.39 μM), which indicates that LnCP 2 is more efficient than most of Eu-based coordination polymers for the sensing of TNP. Furthermore, LnCP 2 represents the first example of one-dimensional Eu-based sensors with formyl group as hydrogen-bonding site in the detection of TNP.

A highly effective "turn-on" camphor-based fluorescent probe for rapid and sensitive detection and its biological imaging of Fe2

In this work, a novel fluorescent probe CBO was synthesized for detecting Fe²⁺ using the natural monoterpenketone camphor as the starting material. The probe CBO displayed turn-on fluorescence to Fe²⁺ accompanied by the solution change from colorless to green. As expected, there was an excellent linear relationship between the fluorescence intensity of probe CBO and the concentration of Fe²⁺ (0-20 μM), and the detection limit was as low as 1.56×10^-8 M. In particular, CBO could selectively sense Fe²⁺ more than other analytes (Fe³⁺ included) through the N-oxide strategy, and quickly responded to Fe²⁺ (60 s) over a wide pH (4-14) range. Additionally, based on the rapid fluorescence response of CBO to Fe²⁺, a simple test strip-based detector was designed for boosting practical applicability. The probe CBO had been successfully applied to the fluorescence imaging of Fe²⁺ in onion cells and living zebrafish. The probe CBO was a powerful tool of detecting Fe²⁺ level in organisms, which was of significance to understand the role of Fe²⁺ in Fe²⁺-related physical processes and diseases.

A novel AIE fluorescent probe based on myrtenal for Cu2+ detection in a near-perfect aqueous medium and bioimaging in vegetables and zebrafish

An AIE-active fluorescent probe MHTS with good sensitivity and selectivity for the detection of Cu2+ was synthesized from myrtenal.