Fluoride-selective colorimetric sensor based on thiourea binding site and anthraquinone reporter.
A structurally simple colorimetric sensor, N-4-nitrobenzene-N'-1'-anthraquinone-thiourea (1), for anions was synthesized and characterized by (1)H NMR, ESI mass and IR methods. In acetonitrile, the addition of F(-) changed 1 solution from colorless to yellow. In the presence of other anions such as CH(3)CO(2)(-), H(2)PO(4)(-), HSO(4)(-) and Cl(-), however, the absorption spectrum of 1 was slightly red shifted with no obvious color changes observed. The association constants of anionic complexes followed the order of F(-)>>CH(3)CO(2)(-)>H(2)PO(4)(-)>HSO(4)(-)>Cl(-)>Br(-), which was different from the order of anion basicity. AM1 calculation results indicated that the most stable configuration of 1 existed in the Z-E-conformation with a six-membered ring via intramolecular hydrogen bond. This made thiourea moiety of 1 in an unfavorable conformation to bond with oxygen-anionic substrates such as CH(3)CO(2)(-) and H(2)PO(4)(-), thus leading to a high selectivity and sensitivity for the detection of F(-).
Wu
Fang-ying
FY
The Center of Analysis and Testing, Department of Chemistry, Nanchang University, Nanchang 330047, China. fangyingwu@163.com <fangyingwu@163.com>
Hu
Mei-hua
MH
Wu
Yu-mei
YM
Tan
Xiao-fang
XF
Zhao
Yong-qiang
YQ
Ji
Zhao-jun
ZJ
D000838:Anions / Q000032:analysis; D000880:Anthraquinones / Q000138:chemical synthesis / Q000737:chemistry*; D001665:Binding Sites; D003124:Colorimetry / Q000379:methods*; D005459:Fluorides / Q000032:analysis*; D013057:Spectrum Analysis; D013890:Thiourea / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry
D000838:Anions; D000880:Anthraquinones; C517281:N-4-nitrobenzene-N'-1'-anthraquinone-thiourea; D013890:Thiourea; D005459:Fluorides