A near IR di-styryl BODIPY-based ratiometric fluorescent chemosensor for Hg(II)

A novel BODIPY-based near-IR emitting probe as a selective and sensitive fluorophore for Hg(II) is synthesized. This versatile BODIPY fluorophore is functionalized for long wavelength emission at the 3 and 5 positions via a condensation reaction in which two dithiodioxomonoaza-based crown-containing phenyl units are conjugated to the BODIPY core as a chelating unit. This designed fluorophore, employing an ICT sensor can be used effectively to detect Hg(II) cations by way of a hypsochromic shift (∼90 nm) in both the absorption and emission spectra.     

A water soluble Al(3+) selective colorimetric and fluorescent turn-on chemosensor and its application in living cell imaging

An efficient water soluble fluorescent Al(3+) receptor, 1-[[(2-furanylmethyl)imino]methyl]-2-naphthol (1-H) was synthesized and characterized by physico-chemical and spectroscopic tools along with single crystal X-ray crystallography. High selectivity and affinity of 1-H towards Al(3+) in HEPES buffer (DMSO/water: 1/100) of pH 7.4 at 25 °C showed it to be suitable for detection of intracellular Al(3+) by fluorescence microscopy. Metal ions, viz. alkali (Na(+), K(+)), alkaline earth (Mg(2+), Ca(2+)), and transition-metal ions (Ni(2+), Zn(2+), Cd(2+), Co(2+), Cu(2+), Fe(3+), Cr(3+/6+), Hg(2+)) and Pb(2+), Ag(+) did not interfere. The lowest detection limit for Al(3+) was calculated to be 6.03 × 10(-7) M in 100 mM HEPES buffer (DMSO/water: 1/100). Theoretical calculations have also been included in support of the configuration of the probe-aluminium complex.     

A fluorescent chemosensor for Cu2+ ions and its application in cell imaging

A new on-off fluorescent probe 1 for Cu²⁺ based on Schiff base compound was designed and synthesized by one-step reaction. The single probe 1 exhibited strong green fluorescence emission. A fluorescence quenching effect and faint color change were observed as soon as the Cu²⁺ was added to the probe system in H₂O/EtOH (v/v = 8:2, HEPES buffer, 0.05 M, pH = 7.4) solution. Other common metal cations did not cause the changes in the fluorescence and color of the probe 1. The optical properties were studied by the fluorescence emission and UV–Vis spectra. Meanwhile, the geometry optimizations of probe 1 and the [1-Cu²⁺] coordination complexes were also carried out by DFT using the Gaussian 09 program, in which the B3LYP function was used. Based on experimental measurement and theoretical analysis, we can know that the combination ratio of the probe and Cu²⁺ is 2:1 and the limit of detection (LOD) is as low as 5.3 × 10^?9 M Besides, the probe 1 was also used to analyze the Cu²⁺ in living cells.     

A potential fluorescent Hg(II) chemosensor

An imidazole-based ligand has been evaluated for a potential fluorescent Hg(II) sensing probe. In water-acetonitrile solvent system, the ligand exhibits a unique selectivity towards Hg(II), which not only modulates fluorescence intensity but also shifts the emission band. The fluorescence reduction and the emission shift correlate with Hg(II) concentrations.     

A selective colorimetric chemosensor for lanthanide ions

The synthesis and complexing properties of a calix[4]arene derivate (6) carrying two spirobenzopyran moieties are described. The addition of lanthanide ions resulted in significant UV-vis spectral shifts (68-84 nm) in visible region. It indicates that the synthetic receptor can recognize lanthanide ions by naked eyes over other cations including Na⁺, K⁺, Mg²⁺, Ca²⁺, Fe³⁺, Cu²⁺ and Zn²⁺. The mechanism of recognition was studied with ¹H NMR, UV-vis spectra and emission spectra. The receptor may be applied to sense lanthanide ions.     

Pyrophosphate-selective fluorescent chemosensor based on 1,8-naphthalimide-DPA-Zn(II) complex and its application for cell imaging

A new zinc(II) complex with a two-dipicolylamine-substituted 1,8-naphthalimide for recognition of pyrophosphate with ratiometrical fluorescence changes in aqueous solution has been synthesized and characterized. Its biological application to monitor the intracellular pyrophosphate (PPi) was successfully demonstrated by the observation that the fluorescence of 1 was enhanced by the presence of the Zn(2+) ion and was quenched by addition of PPi.     

A turn-on chemosensor for Hg2+ in aqueous media and its application in "MCT" imaging in living cells

A turn-on chemosensor L1, which exhibits high selectivity and sensitivity toward Hg(2+) over other common metal ions in aqueous media under a physiological pH window via a 1:1 binding mode, had been synthesized and characterized. L1 provides good fluorescent imaging of Hg(2+) in living cells. Particularly, we adopted the "micro computed tomography (MCT)" technology, successfully demonstrating the method of Hg(2+) sensing by L1 in cell lines, also the cell permeability of L1 and its imaging position in the cells.     

A fluorescent "turn-on" probe for the dual-channel detection of Hg(II) and Mg(II) and its application of imaging in living cells

A novel rhodamine-based fluorescent chemosensor (RND) was synthesized that contains two independent fluorophores and acts as a very sensitive, selective and reversible off-on probe for Hg(II). Importantly, this newly developed sensing system exhibited different fluorescent responses toward Hg(II) and Mg(II) at 589 nm and 523 nm, respectively. RND also displayed detectable color change upon treatment with Hg(II). Results from confocal laser scanning microscopy experiments demonstrated that this chemosensor is cell permeable and can be used as a fluorescent probe for monitoring Hg(II) or Mg(II) in living cells. This probe can also indirectly detect glutathione (GSH) and cysteine (Cys) with good linear relationships.     

Rhodamine-based highly sensitive colorimetric off-on fluorescent chemosensor for Hg2+ in aqueous solution and for live cell imaging

A novel rhodamine-based highly sensitive and selective colorimetric off-on fluorescent chemosensor for Hg(2+) ions is designed and prepared by using the well-known thiospirolactam rhodamine chromophore and furfural hydrazone as signal-reporting groups. The photophysical characterization and Hg(2+)-binding properties of sensor RS1 in neutral N, N-dimethylformamide (DMF) aqueous solution are also investigated. The signal change of the chemosensor is based on a specific metal ion induced reversible ring-opening mechanism of the rhodamine spirolactam. The response of the chemosensor for Hg(2+) ions is instantaneous and reversible. And it successfully exhibits a remarkably "turn on" response toward Hg(2+) over other metal ions (even those that exist in high concentration). Moreover, this sensor is applied for in vivo imaging in Rat Schwann cells to confirm that RS1 can be used as a fluorescent probe for monitoring Hg(2+) in living cells with satisfying results, which further demonstrates its value of practical applications in environmental and biological systems.     

A colorimetric and fluorescent turn-on chemosensor for Al and its application in bioimaging

The sensing properties of a boron dipyrromethene derivative 1 containing a N,N-(dimethylamino)styryl group at its α-position and an aniline moiety at meso-position were investigated by steady-state UV-vis absorption and fluorescence spectroscopy, which were found to exhibit wavelength ratiometric and large fluorescence enhancement in the presence of Al³⁺ with specific selectivity over other metal ions in aqueous media. Furthermore, confocal fluorescence microscopy experiments demonstrated that 1 could be used as a fluorescent probe for Al³⁺ in living cells.     

A fast,highly selective and sensitive dansyl-based fluorescent sensor for copper (II) ions and its imaging application in living cells

Since the copper ions (Cu²⁺) play a fatal role in many foundational physiological processes, it is important to develop a simple, highly sensitive and selective sensor for Cu²⁺ detection in living systems. Herein, an intramolecular charge transfer (ICT) and dansyl-based fluorescent chemosensor 1 was designed, synthesized and characterized for the sensitive and selective quantification of Cu²⁺. It exhibited remarkable fluorescence quenching upon addition of Cu²⁺ over other selected metal ions, attributed to the complex formation between 1 and Cu²⁺ with the association constant 6.7 × 10⁵ M^?1. The sensor 1 showed a fast and linear response towards Cu²⁺ in the concentration range from 0 to 12.5 × 10^?6 mol L^?1 with the detection limit of 2.5 × 10^?7 mol L^?1. This detection could be carried out in a wide pH range of 5.0–14. Furthermore, sensor 1 can be used for detecting Cu²⁺ in living cells.     

A Hg(II)-specific probe for imaging application in living systems and quantitative analysis in environmental/food samples

Mercury ions are highly toxic and can accumulate along food chains in water, soil, crops and animals. Effective detection of mercury ions in various media is of great significance for maintaining the ecological environment and protecting people’s health. In this work, a mercury ions specific fluorescent probe was developed by a simple one-step reaction of commercial substrates of 4-chloro-7-nitro-2,1,3-benzoxadiazole and 1-(2-aminoethyl)-4-methylpiperazine. Investigation on sensing behavior showed that this probe had high sensitivity and selectivity towards mercury ions. Furthermore, this probe could be used as a tool to track the level of mercury ions in living system. In living cells, the probe with green emission emitted a bright red fluorescence when it was bound to mercury ions. In Arabidopsis thaliana, similar red emission could be detected from the root tip and stalk when A. thaliana was grown in culture medium containing mercury ions. The imaging in zebrafish showed that mercury ions were mainly concentrated in the stomach and head of zebrafish. Especially, this probe could be applied in quantitative analysis of mercury ions in tap water, green tea, sea shrimp and soil. This work provided a practical tool for the detection of mercury ions in living systems and quantitative analysis in real samples.     

Single chemosensor for highly selective colorimetric and fluorometric dual sensing of Cu(II) as well as ‘NIRF’ to acetate ion

A novel fluorescent probe for the copper(II) ion in mixed aqueous media, based on fluorescence quenching mechanism with noticeable color change from light to dark yellow, was designed and synthesized. It also exhibited high selectivity for acetate in acetonitrile over other common anions in the near infrared region (NIR) accompanied with exciting color changes from light yellow to pink. Hence sensor 1 ascertains its dual chemosensing ability toward Cu(II) and acetate ions as evidenced by competitive experiments.     

An acyclic,dansyl based colorimetric and fluorescent chemosensor for Hg(II) via twisted intramolecular charge transfer (TICT)

An efficient fluorescent chemosensor for Hg²⁺ ion, based on 5-(dimethylamino)-N-(2-mercaptophenyl)naphthalene-1-sulfonamide, has been developed. It exhibits Hg²⁺-selective on–off fluorescence quenching behavior via twisted intramolecular charge transfer (TICT) mechanism, which is rationalized by time dependent density functional theory (TD-DFT) calculations. The system exhibits visible color change from colorless to gray upon Hg²⁺ binding with very high selectivity and sensitivity (as low as 5.0 × 10⁻¹⁰ mol L⁻¹) over other metal ions such as K⁺, Na⁺, Ag⁺, Mn²⁺, Ca²⁺, Ba²⁺, Fe²⁺, Zn²⁺, Pb²⁺, Cu²⁺, Sn²⁺, Cd²⁺, Ni²⁺ and Co²⁺. The present sensing system is also successfully applied for the detection of Hg²⁺ ion in real samples.     

Novel hemicyanine dye as colorimetric and fluorometric dual-modal chemosensor for mercury in water

A novel water soluble Hg(2+)-selective chemosensor 1 with hemicyanine as fluorescent reporting group and NO(2)Se(2) chelating unit as ion binding site was reported. Chemosensor 1 shows a specific Hg(2+) selectivity and discrimination between Hg(2+) and chemically similar ions in conjunction with a visible colorimetric change from red to colorless, potentially leading to both "naked-eye" and fluorometric detection of Hg(2+) cations.     

A novel highly selective fluorescent chemosensor for Hg（Ⅱ） in fully aqueous media

A novel fluorescent Hg~(2 ) chemosensor based on dithia-dioxa-monoaza crown ether was synthesized in four steps from inexpensive starting materials.This new sensor exhibited very strong fluorescence response to Hg~(2 ) (F_(Hg~(2 ))/F_(free)>130) and it was highly selective to Hg~(2 ) over the other metal ions by more than 45-fold.     

A rhodamine-cyclen conjugate as a highly sensitive and selective fluorescent chemosensor for Hg(II)

A rhodamine-cyclen conjugate (1) behaves as a highly sensitive and selective fluorescent chemosensor for Hg(2+). The high emission selectivity is due to the formation of 1-Hg(2+) 1:2 complex leading to spirocycle opening of 1.     

A highly selective fluorescent chemosensor for zinc ion and imaging application in living cells

A new 2,6-bis(5,6-dihydrobenzo[4,5]imidazo[1,2-c]quinazolin-6-yl)-4-methylphenol (1) serves as a highly selective and sensitive fluorescent probe for Zn(2+) in a HEPES buffer (50 mM, DMSO:water = 1:9 (v/v), pH = 7.2) at 25 °C. The increase in fluorescence in the presence of Zn(2+) is accounted for by the formation of dinuclear Zn(2+) complex [Zn(2)(C(35)H(25)N(6)O)(OH)(NO(3))(2)(H(2)O)] (2), characterized by X-ray crystallography. The fluorescence quantum yield of the chemosensor 1 is only 0.019, and it increases more than 12-fold (0.237) in the presence of 2 equiv of the zinc ion. Interestingly, the introduction of other metal ions causes the fluorescence intensity to be either unchanged or weakened. By incubation of cultured living cells (A375 and HT-29) with the chemosensor 1, intracellular Zn(2+) concentrations could be monitored through selective fluorescence chemosensing.     

A novel colorimetric and fluorescent chemosensor: synthesis and selective detection for Cu and Hg

A novel two-channel metal ion sensor has been synthesized from macrocyclic dioxotetraamine and 1,8-naphthalimide derivative. The metal ion-selective signaling behaviors of the sensor were investigated. The sensor presented the selective coloration for Cu²⁺ and Hg²⁺ that can be detected by the naked-eye, respectively. Besides, the addition of Cu²⁺ and Hg²⁺ quenched the fluorescence of 1 obviously and the detection limit was found to be 3 × 10⁻⁷ M for Cu²⁺ and 7 × 10⁻⁷ M for Hg²⁺. This sensor can be utilized for the visual and spectroscopic detection of Cu²⁺ or Hg²⁺ in the presence of the other competing metal ions.     

A highly selective colorimetric and ratiometric fluorescent chemodosimeter for imaging fluoride ions in living cells

A simple but highly selective colorimetric and ratiometric fluorescent chemodosimeter was designed and synthesized to detect fluoride ions (F(-)) in aqueous solution and living cells by virtue of the strong affinity of F(-) toward silicon.