Coumarin-based fluorescent chemosensor for the selective quantification of Zn2+ and AcO− in an aqueous solution and living cells

In this work, we report a novel fluorescence chemosensor HM based on the coumarin fluorophore for the quantification of Zn²⁺ and AcO^?. HM specifically binds to Zn²⁺ in the presence of other competing cations, and evident changes in UV–vis and fluorescence spectra in HEPES buffer are noticed. The in situ generated HM-Zn²⁺ complex solution exhibit a high selectivity toward AcO^? via Zn²⁺ displacement approach. The detection limits of HM for Zn²⁺ and HM-Zn²⁺ for AcO^? were estimated to be 7.24 × 10^?8 M and 9.41 × 10^?8 M, respectively. HM and the resultant complex HM-Zn²⁺ exhibit low cytotoxicity and cell-membrane permeability, which makes them capable of Zn²⁺ and AcO^? imaging in living Hep G2 cells. A B3LYP/6-31G(d,p) basis set was employed for optimization of HM and HM-Zn²⁺ complex.     

A new coumarin-based fluorescent probe for selective recognition of Cu2+ and S2− in aqueous solution and living cells

A new coumarin-based fluorescent probe CMOH was easily synthesized for detection of Cu²⁺ and S²⁻ in aqueous media and living cells. CMOH displayed high sensitivity (detection limit = 3.2 nM) and selectivity to Cu²⁺ with a non-fluorescence complex CMOH-Cu²⁺ formation via a 1:1 binding mode. According to displacement approach, the fluorescence of CMOH-Cu²⁺ was recovered in the presence of S²⁻ and acted as a sensitive sensor with a low detection limit of 11.4 nM. This ‘‘on-off-on’’ process can be accomplished within 1 min and repeated at least 5 times. What's more, CMOH exhibited good permeability, low cytotoxicity and can be used as a suitable tool to detect changes of Cu²⁺ and S²⁻ in biosystem.     

A new “naked-eye” colorimetric and ratiometric fluorescent sensor for imaging Hg2+ in living cells

A new oligothiophene-based sensor 3 TH for monitoring Hg²⁺ has been designed and synthesized based on the intramolecular charge transfer (ICT) mechanism. The 3 TH shows the significant specificity toward Hg²⁺ through “naked-eye” colorimetric detection as well as via ratiometric fluorescence enhancement response with low detection limit of 62 nM. In addition, sensor 3 TH shows high selectivity and sensitivity for Hg²⁺ with fast response in a suitable pH range. Moreover, the 3 TH-based test strips was used to conveniently detect Hg²⁺ ions in water. Furthermore, considering its good ‘‘turn-on’’ fluorescent sensing behavior and low cell cytotoxicity, 3 TH was successfully applied to detect and image Hg²⁺ in real water samples and living cells, which shows great potentials for application in environmental and biological systems.     

New fluorescent chemosensor for Zn2+ ions on the basis of 3,3′-bis(dipyrrolylmethene)

Luminescence study of the reaction of 3,3′-methanediylbis(2,4,7,8,9-pentamethyldipyrrolylmethene) (H₂L) with a number of metal salts showed that this compound is an efficient fluorescent chemosensor for Zn²⁺ ions in organic solvents. The selectivity and sensitivity of H2L were estimated in various solvents in the presence of other metal cations (Na⁺, Mg²⁺, Co²⁺, Ni²⁺, Cu²⁺, Cd²⁺, Hg²⁺, Pb²⁺).     

Naphthalene thiourea derivative based colorimetric and fluorescent dual chemosensor for F− and Cu2+/Hg2+ ions

A structurally simple (Z)-2-(naphthalen-2-ylmethylene)-N-phenylhydrazinecarbothioamide (R1) was used as a colorimetric and fluorescent sensor for both F^?  and Cu²⁺/Hg²⁺ ions. R1 selectively recognised F^?  ions as indicated by colour change from colourless to green. Fluorescence spectral data reveal that R1 is an excellent fluorescence chemosensor for Cu²⁺ ions. Finally, R1 was successfully applied to the bioimaging of Cu²⁺ ions in RAW 264.7 macrophage cells.     

Phenanthrene-imidazole-based fluorescent sensor for selective detection of Ag+ and F− ions: real sample application and live cell imaging

Research on Chemical Intermediates - 4-Methyl-2,6-bis(1H-phenanthro[9,10-d]imidazol-2-yl)phenol (probe-MPIP) conjugate has been designed as a selective fluorescent probe for silver (Ag+) ions. The...     

A highly selective and sensitive fluorescent chemosensor for Zn^2＋

A new selective Zn^2＋ fluorescent chemosensor, o-vanillin-4-ethoxybenzoylhydrazone （1）, was designed and prepared. Free 1 mainly displayed very weak fluorescence at 480 nm upon excitation at 403 nm. It displayed high selectivity for Zn^2＋ and had a 518- fold fluorescent enhancement upon binding of Zn^2＋, while the other cation ions had only little influence on the fluorescence of 1. Mechanism of enhancement of l＇s fluorescence by Zn^2＋ was briefly discussed.     

A novel chemosensor for Fe3+ based on open–closed-loop mechanism and imaging in living cells

Research on Chemical Intermediates - In this paper, a novel chemosensor (named L1) for Fe3+ based on the rhodamine 6G and o-vanillin has been synthesized, which can selectively recognize Fe3+. The...     

“On–off–on” pyrene-based fluorescent chemosensor for the selective recognition of Cu2+ and S2− ions and its utilization in live cell imaging

A new “on–off–on” fluorescence chemosensor (DPD) was designed, synthesized, and characterized based on pyrene and benzothiozole hydrazide. The probe DPD shows high affinity towards Cu²⁺ ions and the DPD-Cu²⁺ ensemble shows high sensitivity towards S²⁻ ions through the displacement method in the presence of other interfering ions. The detection limits of DPD for Cu²⁺ and S²⁻ ions were found to be 0.73 and 0.87 nM, respectively. Furthermore, the receptor was effectively applied to recognize Cu²⁺ and S²⁻ ions in real samples and live A549 cells through imaging studies.     

A highly sensitive DNA-AIEgen-based “turn-on” fluorescence chemosensor for amplification analysis of Hg~(2+) ions in real samples and living cells

Functional nucleic acids(FNAs)-based biosensors have shown great potential in heavy metal ions detection due to their low-cost and easy to operate merits. However, in most FNAs based fluorescence probes, the ingenious designs of double-labeled(fluorophore and quencher group) DNA sequence, not only bring the annoyance of organic synthesis, but also restrict its use as a robust biosensor in practical duties. In this paper, we design a simple AIEgens functional nucleic acids(AFNAs) probe which consists of only fluorogen but no quencher group. With the help of duplex-specific nuclease(DSN) enzyme based target recycling, high fluorescence signal and superior sensitivity towards Hg~(2+) are achieved. This robust assay allows for sensitive and selective detection of Hg~(2+) in real water samples and mapping of intracellular Hg~(2+), without double-labeling of oligonucleotide with a dye-quencher pair, nor the multiple assay steps.     

A highly selective diarylethene chemosensor for dual channel recognition of CN− and Zn2+ and its application

A novel diarylethene chemosensor comprising 3-aminobenzofuran-2-carboxamide Schiff base (1O) was synthesized and the photophysical and sensing behaviors of 1O were further investigated. Importantly, the introduction of electron-withdrawing group to 1O made the sensor an efficient tool for detection of toxic cyanide even in the presence of other plausible interfering anions including fluoride and acetate. In particular, addition of CN^? to 1O visibly changes the color from colorless to orange-red, which can be observed by the naked eye. Apart from this, it also exhibited an outstanding fluorometric sensing toward Zn²⁺ with high selectivity and sensitivity. Moreover, the remarkable spectral responses of the devised sensor prompted us to fabricate molecular logic circuit. Furthermore, the sensor was successfully applied to the detection of CN^? on test strips and silica coated microslides, and the methods were very simple to operate without resorting to any spectroscopic instrumentation. In addition, the 1O can also effectively detect CN^? and Zn²⁺ in actual water samples.     

A highly selective fluorescent chemosensor for successive detection of Fe3+ and CN− in pure water

A water-soluble fluorescent chemosensor (D) based on 1, 8-naphthalimide derivative has been designed and synthesised as a new fluorescent sensor for successive detection of Fe³⁺ and CN^?. Fluorescence measurements show that chemosensor D has excellent fluorescent-specific selectivity and high sensitivity for Fe³⁺ over many other metal ions in pure water. Moreover, the complex of D and Fe³⁺ (D–Fe³⁺) displayed high sensitivity for CN^? over many other anions in the same medium. Even more important, the recognition of the sensor D for Fe³⁺ and D–Fe³⁺ complex for CN^- could be used successfully in pure water. The test strips based on D and D–Fe³⁺ exhibited good selectivity to Fe³⁺ and CN,^- respectively, we believe the test strips could serve as convenient and efficient Fe³⁺ and CN^? test kits.     

Ferrocene containing N-tosyl hydrazones as optical and electrochemical sensors for Hg2+, Cu2+ and F− ions

Ferrocene containing N-tosyl hydrazones as selective and sensitive optical and electrochemical chemosensors were synthesized and characterized by ¹H NMR, ¹³C NMR, ESI-MS and X-ray analysis. The cation and anion binding studies were carried out using various techniques including electrochemistry, UV–vis and ¹H NMR spectroscopy. Chemosensors 2a and 2b have shown excellent selective recognition toward Hg²⁺, Cu²⁺ and F^? through optical and electrochemical signals. The color of 2a and 2b in solution changed visibly from pale yellow to red upon addition of Hg²⁺ion, while the color of solution changed from pale yellow to yellow green upon addition of Cu²⁺, which can be easily detected by the naked eye.     

A solvent-dependent fluorometric dual-mode probe for Pd2+ and ClO− in living cells

A solvent-dependent probe based on rhodamine was designed, and the sensing behaviors were investigated by spectral properties. Especially, the probe exhibited highly sensitive and selective fluorescence enhancement upon addition of Pd²⁺ in ethanol/PBS (2:8, v/v) and ClO⁻ in DMSO/PBS (1:9, v/v) at physiological range with two kinds of mechanisms. Furthermore, the probe was applied for biological imaging which confirmed that it could be used for monitoring Pd²⁺ and ClO⁻ in living cells with satisfying results.     

[Cd(Sn9)2]6− and [Cd(Ni@Sn9)2]6−: Reactivity and coordination chemistry of empty and Ni-centered [Sn9]4− Zintl ions

To investigate the reactivity of homoatomic clusters [E₉]^4? (E = Si-Pb) and intermetalloid clusters [M@E₉]^q?, the reactions of the Zintl anions [Sn₉]^4? and [Ni@Sn₉]^4? with the CdMes₂ (Mes = Mesitylene) in the presence of 2.2.2-crypt were carried out. Two new compounds [K(2.2.2-crypt)]₆[(Sn₉)Cd(Sn₉)]·en (1) and [K(2.2.2-crypt)]₆[(Ni@Sn₉)Cd(Ni@Sn₉)]·en (2) were afforded. Both 1 and 2 were characterized by single-crystal X-ray diffraction, energy dispersive X-ray (EDX), and electrospray ionization mass spectrometry (ESI-MS), and can be viewed as two [Sn₉]^4? or [Ni@Sn₉]^4? subunits bridged by Cd ion in an η³:η³ coordination mode. Quantum chemical calculations reveal the relationships between the geometries and electronic structures of clusters 2a, [Ni₃Ge₁₈]^4? and [Cu₄@Sn₁₈]^4?. Further electron localization technique (AdNDP method) was performed to explain chemical bonding patterns of 1a.     

σ-Aromaticity-Induced Stabilization of Heterometallic Supertetrahedral Clusters [Zn6Ge16]4− and [Cd6Ge16]4−

In this work, the largest heterometallic supertetrahedral clusters, [Zn₆Ge₁₆]⁴⁻ and [Cd₆Ge₁₆]⁴⁻, were directly self-assembled through highly-charged [Ge₄]⁴⁻ units and transition metal cations, in which 3-center–2-electron σ bonding in Ge₂Zn or Ge₂Cd triangles plays a vital role in the stabilization of the whole structure. The cluster structures have an open framework with a large central cavity of diameter 4.6 Å for Zn and 5.0 Å for Cd, respectively. Time-dependent HRESI-MS spectra show that the larger clusters grow from smaller components with a single [Ge₄]⁴⁻ and ZnMes₂ units. Calculations performed at the DFT level indicate a very large HOMO–LUMO energy gap in [M₆Ge₁₆]⁴⁻ (2.22 eV), suggesting high kinetic stability that may offer opportunities in materials science. These observations offer a new strategy for the assembly of heterometallic clusters with high symmetry.     

Effect of Na+, Li+, Pb2+, Ba2+, Si2+, and Ca2+ cations on force constants of W-O and Mo-O bonds of WO4 2− and MoO4 2− anions in melts

By a matrix method of successive approximations, using perturbation theory, the complete set of force constants has been calculated for the free anions WO,^2– and MoO₄ ^2– and for systems MEO₄ ^2–(M = Na₂ ⁺, Li₂ ⁺, Pb²⁺,Sr²⁺, Ca²⁺; E = W, Mo) on the basis of known frequencies of IR and Raman spectra of the corresponding individual melts. Analysis of the results indicates an increase in the force constants of E-O bond stretching and the bending force constants for AD- and MoO₄ ^2– with increasing specific charge of the cation in a field of singly or doubly charged cations.Deceased.Poltava Engineering Construction Institute. Institute of General and Inorganic Chemistry, Academy of Sciences of the Ukrainian SSSR, Kiev. Translated from Teoreticheskuya i ÉksperimentaI'naya Khimiya, No. 1, pp. 120–123, January–February, 1991. Original article submitted January 12, 1989.