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Two colorimetric and fluorescent probes based on ferrocene derivatives have been designed and synthesized. Among studied anions (F−, AcO−, H2PO4−, Cl−, Br− and I−), probe 1 with p‐nitrophenyl hydrazine structure has the strongest binding ability for F−, as well as probe 2 for H2PO4−. It had strong binding ability and was not affected by other anions. The determination limit of 1 toward F− was 5.0×10−6 mol⋅L−1 which can be used for the trace detection of F−. The interacted process of host–guest accompanied by colorimetric changes and increment in fluorescent intensity of the probes. A 1H‐NMR titration experiment and theoretical investigation indicated that −NH in hydrazine participated in the interaction, and the hydrogen‐bonding formed between the probes and anions. These results provided an essential clue to the developing the colorimetric probe based on hydrazine participation. [ABSTRACT FROM AUTHOR]

Abnormal copper ions (Cu2+) and biothiols have potential impacts on environmental pollution and human health, so the detection of these substances with high selectivity and sensitivity has become an important research topic. In this study, we designed and synthesized two fluorescent probes (L 1 and L 2) based on naphthalene and anthracene derivatives that could specifically detect Cu2+ and biothiols. Owing to the paramagnetic effect of Cu2+, the strong fluorescent intensity was quenched after the addition of Cu2+. When biothiols were added to the solution (L-Cu2+), the fluorescence intensity was significantly enhanced and recovered. So, the interaction process was accompanied with "ON-OFF-ON" phenomenon in fluorescent intensity. Two complexes (L-Cu2+) showed low limit of detection for biothiols (Cys was 3.4 ×10−5 M and GSH was 2.0 ×10−5 M) and weak cytotoxicity (< 150 μg/mL). Theoretical investigation analysis revealed that the intramolecular hydrogen bond existed in the structure of probes and the roles of molecular frontier orbitals in molecular interplay. In addition, two probes also showed good applicability in actual drug Atomolan. The GSH content in the tested Atomolan reached over 99.9% of the labeling which was accord with the percentage of pharmacopoeia. Therefore, two probes have the real application value in the detection of Cu2+, biothiols and drug efficacy in various environments. • Fluorescent probes based on naphthalene and anthracene derivatives. • High selectivity and sensitivity for Cu2 + and biothiols. • Low limit of detection for biothiols and weak cytotoxicity. • Good applicability in actual drug Atomolan. [ABSTRACT FROM AUTHOR]

In order to better monitor the content of Fe3+ and H2S in the biological environment, two new fluorescent probes were designed and synthesized. With the addition of Fe3+, the strong fluorescence emission of two probes was significantly quenched due to the paramagnetic effect of Fe3+. With the further addition of S2−, the fluorescence intensity was quickly restored. Two probes showed high selectivity and strong sensitivity for the detection of Fe3+ and S2−, and the fluorescence intensity "ON-OFF-ON" was accompanied with the interaction process. At the same time, two probes displayed good anti-interference ability which was not interfered by the existence of other ions. In addition, two probes illustrated fast response time to Fe3+, S2− and small cytotoxicity to cells. Therefore, two probes can provide a potential ideal tool for detecting Fe3+ and H2S in organisms and the environment. [ABSTRACT FROM AUTHOR]

A series of potential chiral compounds containing an α,β-unsaturated ketone was developed for anion detection. The interplay of compounds and biological momentous anions (Cl−, H2PO4−, I−, AcO−, HS−, F−, and Br−) was evaluated by UV-vis experiments, fluorescence experiments, and electrochemical tests. By comparison, compound 1 had the best selectivity and compound 5 had the strongest binding ability among the five compounds. And compound 5 had the highest sensitivity to H2PO4− among the measured anions, and it also can be applied to actual samples, the content of H2PO4− tested in the potassium dihydrogen phosphate fertilizer solution reached above 97.5% of the marked content, and the recovery rates were within the range of 98.5–99.1%, attesting that this method was reliable for the test of H2PO4− in fertilizer. Through HRMS titration, circular dichroism and optical rotation experiments, the probable interacted mechanism was proved that the interaction site was the C=C of the α,β-unsaturated ketone structure. In addition, the interacted mechanism was researched from the perspective of chirality. Furthermore, theoretical investigation analysis was introduced to reveal that the roles of molecular frontier orbitals in molecular interplay were determined. Therefore, this series of potential chiral compounds has potential application prospects in anion recognition. [ABSTRACT FROM AUTHOR]

• A new pH sensing strategy was developed based on conjugated polymer nanoparticles. • The probe exhibited a rapid, specific and reversible fluorescence response to pH. • The quantification of intracellular pH was achieved based on the probe. Intracellular pH (pH i) is a critical factor that governs many physiological and pathological processes. Accurate measurement and visual imaging of pH i is of importance and in high demand for biological research and clinical diagnosis. In this paper, a novel strategy of pH-dependent disassembly-assembly of conjugated polymer nanoparticles was developed and successfully applied in constructing an efficient fluorescent probe for intracellular pH sensing and imaging. The nanoparticles-based probe (PTNPs) was prepared by reprecipitation method from a polythiophene derivative (PTNEt 2) with diethylamine group on its side chains. As the acidity of system increased, the disassembly of PTNPs took place due to the electrostatic repulsion between protonated PTNEt 2 chains at low pH. Conversely, once the system recovered to weak alkalinity, the dispersed polymer chains reassembled to form nanoparticles owing to their poor water-solubility at high pH. Thus, PTNPs showed a rapid, highly selective and reversible fluorescence response to pH. Besides, the probe exhibited an ideal p Ka value of 5.71, which was suitable for quantification of intracellular pH values with a linearly proportional range of 4.0–8.0. In view of easy modification properties of conjugated polymers, this proposed strategy could offer a general way for quantifying various biological events inside living cells. [ABSTRACT FROM AUTHOR]

Abstract In pure water system, the specific and rapid detection of cysteine (Cys) is very important and challenging. Herein, a new optical probe was developed for the purpose based on the complex of cupric ion (Cu2+) with a water-soluble conjugated polymer, poly[3-(3- N,N -diacetateaminopropoxy)-4-methyl thiophene disodium salts] (PTCO 2). The fluorescence of PTCO 2 in 100% aqueous solution can almost completely extinguished by Cu2+ ions due to its intrinsic paramagnetic properties. Among various amino acids, only Cys causes immediately the efficient recovery of the Cu2+-quenched fluorescence of PTCO 2 with ~31-folds fluorescence enhancement because of the stronger affinity of Cys to Cu2+ leading to the formation of Cu2+-Cys complex through Cu-S bond and separation of Cu2+ from weak-fluorescent PTCO 2 - Cu(II) ensemble and thereby restoring the free PTCO 2 fluorescence. In tris-HCl buffer solution (2 mM, pH 7.4), the intensity of the restored fluorescence is linear with the concentration of Cys, ranging from 0 to 120 μM and the estimated detection limit of Cys is 3.3 × 10−7 M with the correlation coefficient R = 0.9981. In addition, the PTCO 2 -Cu(II) ensemble probe exhibits low cytotoxicity and good membrane penetration, and its application in living cell imaging of Cys has also been explored. Graphical abstract Specific and fast detection of cysteine (Cys) in pure water was achieved based on a new fluorescent probe PTCO 2 -Cu(II) through replacement strategy. The probe also shows good pH-stability, membrane penetration and biocompatibility, and can be applied to cell imaging of Cys. fx1 Highlights • A specific probe for fast detection of Cys in 100% water was developed. • The probe showed good biocompatibility, and was suitable for cell imaging of Cys. • The sensing mechanism was demonstrated by DFT simulations and XPS study. [ABSTRACT FROM AUTHOR]