A highly selective sequential recognition probe for Zn2+ and HSO4-/H2PO4- based on a diarylethene chemosensor

Development of an activatable Lysosome-targeted fluorescent probe for the detection of endogenous ONOO- levels

The liver plays a crucial role in several important processes in the human body, including metabolism, detoxification, and immune function. When the liver experiences acute injury, it can cause significant harm and requires prompt detection. Traditional biomarkers lack specificity and cannot detect changes in real-time, making them unsuitable for monitoring pathological processes. Recent studies have shown that acute liver injury (ALI) is closely related to oxidative stress, with peroxynitrite (ONOO-) being a vital byproduct of liver metabolism and become a critical biomarker for detecting liver damage. As a result, this research developed an activatable near-infrared fluorescent probe W-3a that can be used to detect endogenous ONOO- in a mouse model of ALI induced by lipopolysaccharides (LPS). The probe has high selectivity and anti-interference ability, with a reaction time <10 min and a detection limit of 85 nM. It was successfully utilized in detecting endogenous ONOO- in cells and live imaging of ALI mice.

Hypochlorous acid-activated near-infrared fluorescent probe for in vivo/exogenous detection and dairy toxicity evaluation

Oxidative stress has been reported to be closely associated with many diseases, and an excessive overdose of hypochlorite (ClO^-) can also induce stress-related diseases. In this study, we designed and synthesized a NIR probe, named W-1a based on computational analysis of DCM (4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran) derivatives for specific detection of ClO^-. The probe exhibited dual fluorescence and colorimetric sensing with a response time of <1 min and a detection limit of 0.15 μM. Additionally, the probe was successfully applied for fluorescence imaging of ClO^- at the cellular level and ebrafish endogenous/exogenous ClO^- assay and dairy toxicity assessment. Thus, we present a potential method for developing an efficient and reliable detection of ClO^- in early stage using near-infrared dyes.

Diestervinyl-functionalized acceptor-acceptor type dithienylethenes with efficient photochromic performance

Exploring novel dithienylethenes (DTEs) with efficient photochromism has drawn increasing attention in virtue of the potential applications for photoelectric functional materials. In this contribution, we presented two novel acceptor-acceptor (A-A) type DTE derivatives (4a and 4b) by incorporating the diestervinyl moieties with strong electron-withdrawing capacity into two sides of DTE skeleton. The corresponding structures were well confirmed by the NMR (¹H and ¹³C) and HRMS. When irradiated alternately with ultraviolet and visible light, 4a and 4b showed efficient photochromism in toluene, chloroform and DMSO, clearly implying a solvent-dependence feature. Moreover, excellent photoswitching behaviors were also observed in the poly(methyl methacrylate) (PMMA) film. The density functional theory (DFT) calculations suggested that strong Acceptor-Acceptor effect plays a dominative role in the efficient photochromic performance. Hence, this study will provide a useful guidance for developing high-performance DTE derivatives in multi-media.

A Highly Selective and Sensitive Sequential Recognition Probe Zn2+ and H2PO4- Based on Chiral Thiourea Schiff Base

A series of novel chiral thiourea fluorescent probes HL₁-HL₆ were designed and synthesized from (1R,2R)-1,2-diphenylethylenediamine, phenyl isothiocyanate, and different substituted salicylic aldehydes. All of the compounds were confirmed by ¹H NMR, ¹³C NMR, and HRMS. They exhibit high selectivity and sensitivity to Zn²⁺ in the presence of nitrate ions with the detection limit of 2.3 × 10^-8 M (HL₅). Meanwhile, their zinc (II) complexes (L-ZnNO₃) showed continuous response to H₂PO₄^- in acetonitrile solution. The identification processes could further be verified by supramolecular chemistry data analysis, X-ray single-crystal diffraction analysis, and theoretical study. The research provides reliable evidence for an explanation of the mechanism of action of thiourea involved in coordination, which is important for the application of thiourea fluorescent probes. In short, the sensors HL₁-HL₆ based on chiral thiourea Schiff base will be promising detection devices for Zn²⁺ and H₂PO₄^-.

Crystal structure of photochromic 3-(5-(2,5-dimethylthiophen-3-yl)-2,2,3,3,4,4-hexafluorocyclopentyl)-2-methylbenzo[b]-thiophene, C20H14F6S2

C20H14F6S2, triclinic, P 1 ‾ $P\overline{1}$ (no. 2), a = 8.6105(19) Å, b = 11.027(3) Å, c = 11.485(3) Å, α = 87.191(3)°, β = 69.130(2)°, γ = 69.679(2)°, V = 952.1(4) Å3, Z = 2, R gt (F) = 0.0344, wR ref (F 2) = 0.0967, T = 296(2) K.

Recent Advancements in Ion-Pair Receptors

Over the past two decades, non-covalent chemistry has introduced various promising artificial receptors and revolutionized the host-guest chemistry. These versatile receptors have particularly been entertained in sensing and recognizing of diverse neutral molecules and/or ionic entities (e. g. anions, cations and ion-pair) of particular interest. Notably, supramolecular chemistry had given birth to a plethora of important molecules, explored in the chemical, biological, environmental, and pharmacological world to resolve the critical issues related to the human health while keeping environmental concerns in mind. Amongst the various types of supramolecular monotopic receptors (anions, cations, and neutral molecules), heteroditopic receptors (ion-pair receptors) consisting of distinct binding sites in one system for both cation and anion, have gained much interest from the scientific community in recent past because of their unique binding abilities. Interestingly, these promising artificial receptors have shown potential applications in sensing, recognition, transport and extraction processes besides their uses in salt/waste purification. Bearing the importance of these systems in mind, we intended to report the recent developments in ion-pair chemistry. Herein, we divided the whole document into three main sections; first one describes the introduction and history of the ion-pairs receptors. The second portion highlights the synthesis and applications of ion-pair receptors in sensing, recognition, molecular machines, photoswitching behaviour, extraction and transport properties, whereas the last part of this manuscript provides concluding remarks as well as future prospects of ion-pair receptors. We hope that this manuscript will be helpful to stimulating researchers around the globe to find out the hidden opportunities in this and related areas.

An Acylhydrazone-Based Fluorescent Sensor for Sequential Recognition of Al3+ and H2PO4. MATERIALS (BASEL, SWITZERLAND) 2021;14:6392. [PMID: 34771920 PMCID: PMC8585233 DOI: 10.3390/ma14216392]

A novel acylhydrazone-based fluorescent sensor NATB was designed and synthesized for consecutive sensing of Al3+ and H2PO4-. NATB displayed fluorometric sensing to Al3+ and could sequentially detect H2PO4- by fluorescence quenching. The limits of detection for Al3+ and H2PO4- were determined to be 0.83 and 1.7 μM, respectively. The binding ratios of NATB to Al3+ and NATB-Al3+ to H2PO4- were found to be 1:1. The sequential recognition of Al3+ and H2PO4- by NATB could be repeated consecutively. In addition, the practicality of NATB was confirmed with the application of test strips. The sensing mechanisms of Al3+ and H2PO4- by NATB were investigated through fluorescence and UV-Visible spectroscopy, Job plot, ESI-MS, 1H NMR titration, and DFT calculations.

Europium(III) complex fluorescent sensor for dual channel recognition of Sn2+ and Cu2+ ions in water

A new europium(III) complex Eu(tta)₃L₁ (1a) (L₁ = (2-(3,5-dimethoxyphenyl)-1H-imidazo[4,5-f][1,10]phenanthroline), tta = 2-thenoyltrifluoroacetone) has been prepared and synthesized. The structure of complex was completely determined by several different analytical techniques including single-crystal X-ray diffraction, ¹H and ¹³C NMR. The crystal structure of the complex 1a belonged to monoclinic system with the space group P2₁/n. Its fluorescent properties were systematically studied in details by adding different metal ions in deionized water. Upon addition of Sn²⁺, its fluorescence intensity was strengthened and centered at 460 nm. And when Cu²⁺ was added, its fluorescence emission intensity was quenched quickly. The LODs for Sn²⁺ and Cu²⁺ were calculated to be 4.52 × 10^-7 mol L^-1 and 1.11 × 10^-7 mol L^-1, respectively. Furthermore, this sensor was successfully employed to monitor Sn²⁺ and Cu²⁺ in practical samples.

A monomolecular platform with varying gated photochromism

In the development of modern high-performance photoelectric materials, the gated photochromic materials have attracted wide attention. However, the integration of varying signal regulations into gated photochromism to construct efficient photochromic materials is still an urgent necessity. Herein, we designed and synthesized a new gated photoswitching DTEP based on a Schiff base with a diarylethene core. The photochromic properties of compound DTEP can be regulated to different degrees by multiple stimuli, including UV/visible light, Cu²⁺ and Ni²⁺. The compound DTEP showed different response abilities to Cu²⁺ and Ni²⁺, due to the diverse complexation modes between DTEP and Cu²⁺ as well as Ni²⁺. The photochromic properties of compound DTEP could be inhibited completely by the introduction of Cu²⁺ to form a 1 : 1 complexation, while the weak gated photochromism could be found from the DTEP–Ni²⁺ complex in a 1 : 2 stoichiometry. Relying on such varying degrees of gated photochromic properties, a new molecular logic circuit was constructed to undertake complicated logical operations.

A strategy to realize varying degrees of gated photochromic properties by coordinating with different metal ions within one unimolecular system was devised to achieve the construction of a logic circuit for multi-functional molecular switching.