Fluorescent chemical sensor based on double N2O2 cavities for continuous recognition of Cu2+ and Al3+

A highly selective and recyclable fluorescent sensor based on a Salamo-Salen-Salamo type ligand for continuous detection of Al3+ and phosphates in drug

In this work, a fluorescence chemical sensor continuous detection Al3+ and phosphates by a Salamo-Salen-Salamo type compound (SL) was employed. The sensor continuously recognized Al3+ and phosphates with good selectivity and fast response time, and a low limit of detection of 0.25 μΜ and 0.96 μM, at the same time accompanied by a naked-eye identification specificity. The detection mechanism of SL towards Al3+ is due to the chelating fluorescence enhancement effect and ICT effect, and continuously towards phosphates is due to the collapse of the SL-Al3+ and coordination interaction between Al3+ and phosphates, by Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, other spectral characterization and DFT calculation as evidence. In addition, the sensor had good recyclability and reusability. The distribution of Al3+ and phosphates in zebrafish cells was effectively monitored by confocal microscopy based on the good biocompatibility and tissue permeability of SL. Furthermore, the feasibility of using sensor SL to detect the content of Al3+ and phosphate ions in certain drugs was quantitatively analyzed through experiments. It was found SL had a good result in practical application.

Synthesis, Characterization and Application of Iron (III) Complex of Schiff Base Ligand as a Novel Enhancement Fluorescent Sensor for Al3+ Ion Detection

This study highlights the importance of developing sensitive and selective sensors for use in pharmaceutical applications for the first time. A novel iron(III)-complex, constructed from unsymmetrical tetradentate NNN'O type Schiff base ligand (E)-3-((6-aminopyridin-2-yl)imino)-1-phenyl butane-1-one (LH) and its structure of it characterized by using various spectroscopic techniques such as FT-IR, UV-Vis, elemental analysis, conductivity, magnetic susceptibility measurements and the TGA method. The correlation of all results revealed that the coordination of the (LH) with the metal ion in a molar ratio of 1:1 leads to the formation of an octahedral geometry around the metal ions. Conductivity data showed the electrolytic nature of the complex. Its fluorescence properties were thoroughly investigated by introducing aluminium ions in deionized water, which increased fluorescence intensity at 460 nm. The detection limit for Al3+ was optimized and found to be 1.5 µM. Notably, the fluorescent sensor successfully monitored Al³⁺ in pharmaceutical formulations. This fluorescence-based analytical method is an alternative to other methods due to its high selectivity, sensitivity, and speed. These results suggest the high potential of this system for pharmaceutical monitoring applications.

A highly selective and sensitive salamo-salen-salamo hybrid fluorometic chemosensor for identification of Zn2+ and the continuous recognition of phosphate anions

A salamo-salen-salamo hybrid fluorescent chemical sensor (H₄L) was synthesized and characterized. It exhibits high selectivity and sensitivity to Zn²⁺ in physiological pH range. Meanwhile, its zinc(II) complex (L-Zn²⁺) continuously responses phosphate anions in DMF/H₂O (v/v, 9:1) solution. Moreover, the identification processes are explored using characterization methods such as UV-absorption spectra, IR spectra and ESI-MS spectrum. In addition, the coordination mechanism of H₂PO₄^- and Zn²⁺ were successfully exploited to make the chemical sensor reproducible. In short, the sensors H₄L and L-Zn²⁺ will be promising detection devices for Zn²⁺ and phosphate anions.

Chelate-free “turn-on”-type fluorescence detection of trivalent metal ions

For the detection of trivalent ions, the chelate-free pH-responsive “Turn-ON”-type fluorescence probes based on INAs were constructed. Based on the X-ray analysis, cationic INAs formed unique outer-sphere complexes for AlIII ions.

Novel single-armed nitrogen-heterocyclic salamo-based fluorescent sensors for the detection of Al3+ and CN. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021;258:119815. [PMID: 33930852 DOI: 10.1016/j.saa.2021.119815]

Two novel single-armed nitrogen-heterocyclic chemosensors with basically similar structures, PDNS and PZNS, were synthesized to specifically identify Al³⁺ in DMS:H₂O (1:1 v/v) solution by fluorescence emission spectroscopy, and the colour of PDNS and PZNS changed from yellow to colorless when Al³⁺ was added under daylight. This is the first time that nitrogen-heterocyclic is introduced into salamo-based chemical sensor. At excitation wavelengths of 361 and 365 nm, solutions of PDNS and PZNS changed to intense green-blue fluorescence. Furthermore, it was found that PDNS/PZNS and Al³⁺ have excellent binding capacity, the lower limit of detection (LOD = 6.25 × 10^-9/1.26 × 10^-9 mol·dm^-3) is also calculated. In addition, sensor PZNS can detect Al³⁺ in a solution system with up to 95% water content and applicable pH range is 3-12. Compared to other salamo-based sensors, PZNS and PDNS have broader detection conditions and wider utilities. PZNS can also identify CN^- in fluorescence spectrum. PZNS can be used for detection of Al³⁺ in aqueous systems in daily production and life.

A Bis(Salamo)-Based Fluorogenic Sensor for Highly Selective and Sequential Recognition of Cu2+ and B4O72- Ions in Semi-Aqueous Medium

A new type of multifunctional bis(salamo)-based fluorogenic sensor H₂BS was designed and synthesized. Under the action of V_DMF: V_H2O = 9: 1, the fluorogenic sensor can identify Cu²⁺ and B₄O₇^2-, in which N and O atoms can serve as binding sites for Cu²⁺ and B₄O₇^2-, the stoichiometry of the binding of the fluorogenic sensor H₂BS and Cu²⁺ has been confirmed by titration experiment, working curve, ESI-MS analysis and DFT calculation. The pH response experiment also confirmed that the fluorogenic sensor can recognize Cu²⁺ and B₄O₇^2- in the pH range applicable to the physiological environment. The minimum detection limit of H₂BS for Cu²⁺ and B₄O₇^2- recognition reaches 1.12 × 10^-7 and 5.56 × 10^-8 M, and the fluorogenic sensor H₂BS has been successfully applied to Cu²⁺ detection in actual water samples, and the test strip for detecting Cu²⁺ and B₄O₇^2- was obtained. Meanwhile, the success of the test strip experiment made the fluorogenic sensor H₂BS to recognize Cu²⁺ and B₄O₇^2- widely used in daily life. A new type of salamo-based multifunctional fluorogenic sensor H₂BS was designed and synthesized to identify Cu²⁺ and B₄O₇^2- in aqueous solvent systems. Added Cu²⁺ to H₂BS can cause fluorescence quenching. Further experiments showed that H₂BS and Cu²⁺ form a stable 1:2 complex, while B₄O₇^2- can also cause fluorescence quenching of H₂BS, which is the occurrence of the PET effect. Meanwhile, H₂BS can be used for quantitative detection in the environment and rapid identification in life.

A newly synthesized visual bis(salamo)-based fluorescent chemosensor for exogenous detection of B4O72- in living cells and zebrafish

A newly synthesized fluorescent chemosensor H₆L was explored for detecting B₄O₇^2-, characterized by ¹H NMR spectrum, mass spectrum and fluorescence spectra. During the detection process of B₄O₇^2-, the fluorescence is significantly enhanced and naked eye recognition can be performed under 365 nm UV light without any interference by other typical anions. The limit of detection is as low as 6.97 × 10^-10 M. In addition, in order to broaden the application of salamo-based fluorescence sensors in the field of biology, except for the fluorescence imaging of HeLa cells, the first attempt of exogenous detection in zebrafish was conducted successfully.

Insight into Rare Structurally Characterized Homotrinuclear CuII Non-Symmetric Salamo-Based Complex

A rare homotrinuclear CuII salamo-based complex [Cu3(L)2(μ-OAc)2(H2O)2]·2CHCl3·5H2O was prepared through the reaction of a non-symmetric salamo-based ligand H2L and Cu(OAc)2·H2O, and validated by elemental analyses, UV-Visible absorption, fluorescence and infrared spectra, molecular simulation and single-crystal X-ray analysis techniques. It is shown that three CuII atoms and two wholly deprotonated ligand (L)2− moieties form together a trinuclear 3:2 (M:L) complex with two coordination water molecules and two bi-dentate briging μ-acetate groups (μ-OAc−). Besides, the Hirshfeld surface analysis of the CuII complex was investigated. Compared with other ligands, the fluorescent strength of the CuII complex was evidently lowered, showing that the CuII ions possess fluorescent quenching effect.

A novel turn-on fluorogenic aldehyde-appended salamo-like copper(ii) complex probe for the simultaneous detection of S2O32− and GSH

A novel salamo-like copper(ii) complex probe (ASC) behaves as a two-pronged sensor of S₂O₃²⁻ ions and GSH by a ‘turn-on’ fluorescence mechanism.

A new salamo-based colorimetric and fluorescent turn-on sensor with aggregation-induced emission for the rapid and highly sensitive detection of cyanide in real samples

A new, simple, and easy-to-manufacture highly selective and sensitive dual-mode sensor A1 with the aggregation-induced emission properties is used for CN⁻ colorimetric and fluorescence detection.