Turn-on naphthalimide fluorescent sensor with high quantum yield and large Stokes shift for the determination of Cu(II)

Halochromic Polymer Nanosensors for Simple Visual Detection of Local pH in Coatings

Replacing metallic structures before critical damage is beneficial for safety and for saving energy and resources. One simple approach consists in visually monitoring the early stage of corrosion, and related change of pH, of coated metals. We prepare smart nanoparticle additives for coatings which act as a pH sensor. The nanoparticles are formed with a terpolymer containing two dyes as side chains, acting as donor and acceptor for a FRET process. Real time monitoring of the extent of localized corrosion on metallic structures is then carried out with a smartphone camera. Colored pH mapping can be then manually retrieved by an operator or automatically recorded by a surveillance camera.

A hydrophilic naphthalimide-based fluorescence chemosensor forCu2+ ion: Sensing properties, cell imaging and molecular logic behavior

In this work, a hydrophilic naphthalimide-based fluorescence chemosensor (sensor 1) was synthesized for Cu²⁺ recognition, in which 2-(2-aminoethoxy)ethanol was introduced to improve the hydrophily and Schiff base acted as the multidentate ligand for Cu²⁺. The effect factors, sensing mechanism and regenerability of sensor 1 for Cu²⁺ sensing were systematically investigated. It was found that sensor 1 displayed a long emission wavelength of 532 nm upon excited in visible light region (436 nm), and the good water solubility made it utilized in aqueous media. It could selectively react with Cu²⁺ over other common metal ions to form a 2:1 complex within 1 min and result in significant fluorescence quench. The fluorescence change was linear to 0.5-10.0 μmol L^-1 of Cu²⁺ with a low detection limit of 3.74 × 10^-8 mol L^-1. Sensor 1 has been successfully utilized for analyzing Cu²⁺ in water samples as well as imaging cellular Cu²⁺. Moreover, in view of fluorescence "on-off-on" switches of sensor 1 induced by Cu²⁺ and EDTA, an IMPLICATION logic gate was constructed based on fluorescence mode with Cu²⁺ and EDTA as inputs.

A new 1,8-naphthalimide-based fluorescent “turn-off” sensor for detecting Cu2+ and sensing mechanisms

In this article, a new “turn-off” fluorescent sensor N- n-butyl-4-{2-[(ethylimino)methyl]phenol}-1,8-naphthalimide (HL) for CuII ions is synthesized, which contains a 1,8-naphthalimide moiety as the fluorophore and a Schiff base as the recognition group. As expected, it exhibits high selectivity and sensitivity for detecting CuII ions over other common metal ions in acetonitrile–2-(4-(2-hydroxyethyl)-1-piperazinyl)-ethanesulfonic acid (HEPES) (1:1 v/v, pH = 7.4) solution. In addition, the fluorescence intensity for HL showed a good linearity with the concentration of CuII ions in the range of 0.5–5.0 μM. The 2:1 binding stoichiometry between HL and CuII ions was established on the basis of combined fluorescence titrations, a Job’s plot, single-crystal X-ray analysis and mass spectrometry. The quenching response of HL toward CuII ions is attributed to the reverse photoinduced electron transfer mechanism. The proposed sensor HL is preliminarily applied to quantify CuII ions in water samples from the Yellow River and tap water.

Remarkable colorimetric sensing behavior of pyrazole-based chemosensor towards Cu(ii) ion detection: synthesis, characterization and theoretical investigations

We report the synthesis of a new imine based ligand, 3-((3-methoxybenzylidene)amino)-1H-pyrazol-5-ol (HL) and its Cu(ii) complexes in 2 : 1 (HL : metal) and 1 : 1 : 1 (HL : metal : HQ) stoichiometric ratio using 8-hydroxyquinoline (HQ) as an additional bidentate ligand. The synthesized ligand (HL) and its Cu(ii) complexes (1 and 2) are structurally characterized using FT-IR, electronic absorption and emission, NMR and MS techniques. Furthermore, the complexation of Cu2+ with HL leads to the immediate formation of brown colour solution which indicates that HL can act as simple colorimetric sensor for Cu2+ ions. We further investigated that the sensor could selectively bind to the Cu2+ ions even in the presence of competitive ions such as Mn2+, Fe2+, Co2+, Ni2+, Zn2+, Ag+ and Na+ ions in aqueous solutions which was studied by electronic absorption spectroscopy. The HL ligand has been investigated for its reactive properties by density functional theory (DFT) calculations. Quantum molecular descriptors describing local reactive properties have been calculated in order to identify the most reactive molecule sites of title compounds. DFT calculations encompassed molecular electrostatic potential (MEP), local average ionization energies (ALIE), Fukui functions and bond dissociation energies for hydrogen abstraction (H-BDE).

Novel Cu2+-specific “Turn-ON” fluorescent probe based on [5]helicene with very large Stokes shift and its potential application in living cells

The sensor provides Cu²⁺-sensitive with low detection limit and very large Stokes shift, and can induce the emission in the HepG2 cellular system.

Triple detection modes for Hg2+ sensing based on a NBD-fluorescent and colorimetric sensor and its potential in cell imaging

The sensor provides highly Hg²⁺-sensitivity and can enhance the emission in live cell.

A highly selective naphthalimide-based ratiometric fluorescent probe for the recognition of tyrosinase and cellular imaging

Upon the addition of tyrosinase to the probe solution, the monophenolic unit is oxidized to o-dihydroxy and consequently releases the 4-aminonaphthalimide unit.

Exploration of an easily synthesized fluorescent probe for detecting copper in aqueous samples

Bonding behavior and spectral response studies of an easily synthesized fluorescent probe for the detection of Cu²⁺ ions and CuO NPs in aqueous samples.