A versatile chemosensor 1 (E)-2-(((8-hydroxy-2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1-ij]quinolin-9-yl)methylene)amino)-1H-benzo[de]isoquinoline-1,3(2H)-dione, based on naphthalimide and julolidine moieties, was developed for highly distinguishable and selective recognition of Group IIIA metal ions (Al3+, Ga3+ and In3+). Sensor 1 exhibited significant 'off-on' fluorescence responses at 488 nm in the presence of Al3+ and at 570 nm in the presence of Ga3+ and In3+. The same emission of Ga3+ and In3+ could be distinguished through different color changes (from colorless to yellow for Ga3+ and no color change for In3+). Binding constants of 1 for Ga3+ and In3+ are the highest reported to date for an organic chemosensor. A 2 : 1 binding mode between 1 with Al3+, Ga3+ and In3+ is proposed based on electrospray ionization mass spectrometry, Job plot analysis, and theoretical calculations.
A new multifunctional chemosensor 1, (E)-2-(((2-hydroxynaphthalen-1-yl)methylene)amino)-1H-benzo[de]isoquinoline-1,3(2H)-dione, based on naphtalimide and naphthaldehyde was developed, which showed the fluorescence responses to trivalent metal ions (Ga, Al and Cr). Sensor 1 detected and differentiated selectively trivalent metal ions Ga, Al and Cr by fluorescence enhancement at different emissions. The association constant of Ga-2∙1 complex is the highest one among those of the organic chemosensors reported, to date. The sensing mechanisms for Ga, Al and Cr were explained by UV-vis titrations, Job plots, ESI-mass analyses and theoretical calculations.
A new
dansyl-based chemosensor (2-(4-((5-(dimethylamino)naphthalen-1-yl)sulfonyl)piperazin-1-yl)-
N
-(quinolin-8-yl)acetamide) (
DC)
for detecting
Cu
2+
was synthesized and characterized.
DC
showed great selectivity to Cu
2+
by a fluorescent “on–off”
detection method. Job plot, ESI-mass spectroscopy, and
1
H NMR titration suggested a 1 to 1 binding mode between
DC
and Cu
2+
. The detection limit was determined to be 43
nM, which is greatly below the WHO guidelines. In addition,
DC
can be applied to real samples and zebrafish imaging. The
fluorescence quenching mechanism was proposed as the enhancement of
intramolecular charge transfer with calculations.
A novel fluorescent turn-on chemosensor DHADC ((E)-3-((4-(diethylamino)-2hydroxybenzylidene)amino)-2,3-dihydrothiophene-2-carboxamide) has been developed and used to detect Zn 2+ and CN − . Compound DHADC displayed a notable fluorescence increase with Zn 2+ . The limit of detection (2.55 ± 0.05 µM) for zinc ion was far below the standard (76 µM) of the WHO (World Health Organization). In particular, compound DHADC could be applied to determine Zn 2+ in real samples, and to image Zn 2+ in both HeLa cells and zebrafish. Additionally, DHADC could detect CN − through a fluorescence enhancement with little inhibition with the existence of other types of anions. The detection processes of compound DHADC for Zn 2+ and CN − were demonstrated with various analytical methods like Job plots, 1 H NMR titrations, and ESI-Mass analyses.
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