It is still a significant challenge to develop a Zn(2+)-selective fluorescent sensor with the ability to exclude the interference of some heavy and transition metal (HTM) ions such as Fe(2+), Co(2+), Ni(2+), Cu(2+), Cd(2+), and Hg(2+). Herein, we report a novel amide-containing receptor for Zn(2+), combined with a naphthalimide fluorophore, termed ZTRS. The fluorescence, absorption detection, NMR, and IR studies indicated that ZTRS bound Zn(2+) in an imidic acid tautomeric form of the amide/di-2-picolylamine receptor in aqueous solution, while most other HTM ions were bound to the sensor in an amide tautomeric form. Due to this differential binding mode, ZTRS showed excellent selectivity for Zn(2+) over most competitive HTM ions with an enhanced fluorescence (22-fold) as well as a red-shift in emission from 483 to 514 nm. Interestingly, the ZTRS/Cd(2+) complex showed an enhanced (21-fold) blue-shift in emission from 483 to 446 nm. Therefore, ZTRS discriminated in vitro and in vivo Zn(2+) and Cd(2+) with green and blue fluorescence, respectively. Due to the stronger affinity, Zn(2+) could be ratiometrically detected in vitro and in vivo with a large emission wavelength shift from 446 to 514 nm via a Cd(2+) displacement approach. ZTRS was also successfully used to image intracellular Zn(2+) ions in the presence of iron ions. Finally, we applied ZTRS to detect zinc ions during the development of living zebrafish embryos.

A Cu(II)-sensing, ratiometric, and selective fluorescent sensor 1, N-butyl-4,5-di[(pyridin-2-ylmethyl)amino]-1,8-naphthalimide, was designed and synthesized on the basis of the mechanism of internal charge transfer (ICT). In aqueous ethanol solutions of 1, the presence of Cu(II) induces the formation of a 1:1 metal-ligand complex, which exhibits a strong, increasing fluorescent emission centered at 475 nm at the expense of the fluorescent emission of 1 centered at 525 nm. [structure: see text]

In this work, a 1,8-naphthalimide-derived fluorescent probe for H 2 S based on the thiolysis of dinitrophenyl ether is reported. This probe exhibits turn-on fluorescence detection of H 2 S in bovine serum and lysosome-targetable fluorescent imaging of H 2 S with excellent selectivity.Hydrogen sulfide (H 2 S) is well-known as a toxic gas with the characteristic smell of rotten eggs, but is now also considered the third most important gasotransmitter for regulating cardiovascular, neuronal, immune, endocrine, and gastrointestinal systems, along with nitric oxide and carbon monoxide.1 H 2 S is produced endogenously in mammalian systems from L-cysteine in reactions catalyzed mainly by two pyridoxal-5 0 -phosphate-dependent enzymes, cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE (6) Eto, K.; Asada, T.; Arima, K.; Makifuchi, T.; Kimura, H.