Research On Colorimetric And Fluorescent Probes Based On 1,8-naphthalimide And Thiourea

In this paper, we synthesized three kinds of colorimetric and fluorescent probes(ATBN, BTBN, ATUN) based on 1,8-naphthalimide and thiourea. The structures of the probes were characterized by FT-IR, LC-MS, 1H NMR, 13 C NMR and elementary analysis. The sensing behaviors, sensing mechanism and application of the probes for F-, Fe3+, Pb2+ and Hg2+ were explored by UV-Vis absorption and fluorescence spectra.A colorimetric probe for F-(ATBN): The colorimetric probe(ATBN) for F- was synthesized by N-butyl-4-nitro-1,8-naphthalimide reacted with thiosemicarbazide. On addition of F-, a new absorption band centered at 555 nm was appeared accompanied by the color change of ATBN solution from pale yellow to purple in Me CN(containing a little water). In the scope of 10~50 μM of F- concentration, the absorbance of the solution kept good linear relationship with the F- concentration. The detection limit was 51.1 μM and the binding constant was 1.45×105 M-1. ATBN complexed with F- through hydrogen bonds to form a 1:1 complex.A multifunctional colorimetric and fluorescent probe for Fe3+, Pb2+ and Hg2+(BTBN): BTBN was synthesized by reacting N-butyl-4-hydrazine-1,8-naphthalimide with phenyl isothiocyanate. BTBN can colorimetrically detect Fe3+ and Pb2+ in Me CN/H2O(99/1, v/v) and fluorimetrically detect Hg2+ in Me CN/H2O(85/15, v/v). The linear concentration range for Fe3+ was 0~150 μM with the detection limit of 6.86 μM and the binding constant was 1.854×103 M-1. The linear concentration range for Pb2+ was 0~80 μM with the detection limit of 5.09 μM and the binding constant was 4.961×103 M-1. BTBN bound Fe3+(or Pb2+) reversibly according to 1:1 stoichiometry. In the Hg2+ concentration range of 0~90 μM, BTBN could irreversibly detect Hg2+ by fluorescence. The detection limit was 82.1 n M and the binding constant was 6.334×103 M-1. A 1:1 complex was formed between BTBN and Hg2+ first and then promoted the desulfurization cyclization. Moreover, BTBN was successfully employed to monitor Hg2+ in pond and tap water as well as in living cells.A polymerizable multifunctional colorimetric and fluorescent probe for Fe3+, Pb2+ and Hg2+(ATUN): Allyl amine replaced n-butylamine in BTBN synthesis to get a polymerizable multifunctional colorimetric and fluorescent probe ATUN. Similarly to BTBN, ATUN could colorimetrically detect Fe3+ and Pb2+ in Me CN/H2O(99/1, v/v) and fluorimetrically detect Hg2+ in Me CN/H2O(50/50, v/v). As a colorimetric probe for Fe3+, the linear concentration range was 0~150 μM with the detection limit of 8.34 μM. As a colorimetric probe for Pb2+, the linear concentration range was 0~70 μM with the detection limit of 11.22 μM. As a fluorescent probe for Hg2+, the linear concentration range was 0~80 μM with the detection limit of 139.3 n M. A 1:1 complex was formed between ATUN and Fe3+(or Pb2+, or Hg2+), and the binding constants were 1.254×103, 3.561×103, and 6.353×103 M-1, respectively.