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A novel ratiometric fluorescence and colorimetric probe (BDT-PBES) based on benzo[1,2-b:4,5-b’]dithiophene (BDT) unit, for the detection of Hg 2+ , was developed with dithioacetal group as the response unit. Based on the Hg 2+ -promoted dithioacetal deprotection reaction mechanism, the probe displayed high selectivity for Hg 2+ over other ions including Co 2+ , Mn 2+ , Zn 2+ , Ag+, Cd2+, Pb 2+ , Ca 2+ , Al 3+ , Cr 3+ , Na + , Cu 2+ , Mg 2+ , Ni 2+ , K + , Fe 2+ , Pd 2+ and Fe 3+ . The detection limit reached as low as 3.1 × 10–7 M. When Hg 2+ existed, the maximum absorption peaks were obviously red-shifted with a solution color change from clarifying to light yellow, and the fluorescence changed with a large Stokes shift (179 nm) from blue-green to yellow. [ABSTRACT FROM AUTHOR]

Based on benzothizazole and 1,8-naphalimide, a novel colorimetric and fluorescent probe (probe 1 ) for fluoride ion was synthesized by Schiff base reaction. The striking yellow-to-blue color change of the probe 1 in the CH 3 CN was observed with the naked eyes only in presence of F − among the eight anions (F − , Cl − , Br − , I − , NO 3 − , HSO 4 − , H 2 PO 4 − , AcO − ). Besides that, upon addition of F − , both of the absorption and emission peaks shifted to near-infrared region (NIR) (>600 nm) in UV–vis and fluorescent spectra, and the detection limit reached as low as 0.41 μM. Furthermore, the 1 H NMR titration and theoretical calculation based on TD-DFT indicated that the fluoride ion induced deprotonation of the probe 1 through hydrogen bonding interaction between amino group of probe 1 and fluoride ion. [ABSTRACT FROM AUTHOR]

A novel coumarin-based compound 1 featuring thiosemicarbazone as binding unit, was reported as a colorimetric and fluorescent probe for the detection of fluoride anion. The addition of F − to a solution of probe 1 in tetrahydrofuran resulted in evident naked-eye color change from green-yellow to orange-red under daylight and obvious fluorescence quenching within 3 s. And the detection limit toward F − was calculated to be as low as 2.16 × 10 −7 mol/L. 1 H NMR titrations proved that the interaction between 1 and fluoride ion: hydrogen bond at low fluoride ion concentration, deprotonation at high fluoride ion concentration. Besides, it exhibited highly sensitivity and selectivity for F − over other examined ions (Cl − , Br − , I − , AcO − , NO 3 − , HSO 4 − , H 2 PO 4 − ) in tetrahydrofuran solution. [ABSTRACT FROM AUTHOR]

A new colorimetric fluorescent probe, 3-benzothiazolyl-coumarin-7-yl picolinate (P1) , based on coumarin derivative has been designed and synthesized to detect Cu 2+ in CH 3 CN-water (1:1,v/v) solution. The probe showed highly selective and sensitive fluorescence enhancement response towards Cu 2+ via selective hydrolysis reaction of the picolinate moiety followed by generating a strongly fluorescent 3-benzothiazolyl-7-hydroxycoumarin ( 2 ) moiety, whereas other competing metal cations (Na + , K + , Mg 2+ , Ag + , Fe 3+ , Pb 2+ , Mn 2+ , Ca 2+ , Ni 2+ , Cr 3+ , Zn 2+ , Sn 2+ , Hg 2+ , Al 3+ , Pd 2+ , Pt 2+ , Co 2+ , Au 3+ ) did not possess the property. Upon the addition of Cu 2+ , the color of P1 changed from colorless to yellow-green, and gave an emission at around 470 nm. Moreover, the detection limit toward Cu 2+ was calculated to be as low as 23.9 nM. [ABSTRACT FROM AUTHOR]

Two novel 2,1,3-benzothiadiazole derivatives, used as colorimetric and fluorescent sensors for fluoride ion were designed, synthesized and characterized. These sensors contained single hydrogen-bond functional groups, which acted as interacting sites for fluoride ion. Both sensors displayed a red color in dimethyl sulfoxide solution. Binding studies revealed that they showed noticeable colorimetric and fluorescent responses only to F − among the eight anions tested (F − , Cl − , Br − , I − , AcO − , H 2 PO 4 − , HSO 4 − and NO 3 − ). 1 H NMR titration proved that the interaction between compounds and fluoride ion: hydrogen bond at low fluoride ion concentration, deprotonation at high fluoride ion concentration. Moreover, those compounds showed high sensitivity and selectivity for fluoride ion by inhibiting the excited state intramolecular proton transfer processes, and the detective processes could be followed by direct visual observation. [ABSTRACT FROM AUTHOR]