title: Ligand-doped liquid crystal sensor system for detecting mercuric ion in aqueous solutions.
abstract: We developed a liquid crystal (LC) sensor system for detecting mercuric ion (Hg(2+)) in aqueous solutions. In this system, 4-cyano-4'-pentyl biphenyl (5CB) was doped with a sulfur- and nitrogen-containing ligand 5-(pyridine-4-yl)-2-(5-(pyridin-4-yl)thiophen-2-yl)thiazole (ZT) as the Hg(2+) specific LCs. When the system was immersed in the solution containing Hg(2+), the complex of ZT and Hg(2+) formed, which disrupted the orientation of LC and lead to a dark-to-bright transition of the image of LCs. From mercuric binding titrations monitored by UV-vis spectroscopy, it was found that 1:1 Hg(2+)/ZT complexes were formed. The limit of detection (LOD) of the system to Hg(2+) is 10 μM, and it did not respond to Cd(2+), Zn(2+), Cu(2+), Pb(2+), Fe(+), Mg(2+), Ca(2+), Na(+), and K(+). Besides, we also demonstrated that this system is capable of detecting Hg(2+) in tap water and pond water. Because the signal of this system is colorful under ambient light, which is readily understood by normal users, it can be used as a portable device to monitor the water quality at any location.
authors.affiliation: Department of Chemistry, Tamkang University, New Taipei City 25137, Taiwan.
authors.forename: Chih-Hsin
authors.initials: CH
authors.lastname: Chen
authors.affiliation: Department of Chemistry, Tamkang University, New Taipei City 25137, Taiwan.
authors.forename: Yi-Cheng
authors.initials: YC
authors.lastname: Lin
authors.affiliation: Department of Chemistry, Tamkang University, New Taipei City 25137, Taiwan.
authors.forename: Hao-Hsiang
authors.initials: HH
authors.lastname: Chang
authors.affiliation: Department of Chemistry, Tamkang University, New Taipei City 25137, Taiwan.
authors.forename: Adam Shih-Yuan
authors.initials: AS
authors.lastname: Lee
mesh_terms: D007477:Ions / Q000032:analysis; D008024:Ligands; D050866:Liquid Crystals / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008628:Mercury / Q000032:analysis*; D012996:Solutions; D013056:Spectrophotometry, Ultraviolet; D013844:Thiazoles / Q000138:chemical synthesis / Q000737:chemistry*; D013876:Thiophenes / Q000138:chemical synthesis / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: C000602113:5-(pyridine-4-yl)-2-(5-(pyridin-4-yl)thiophen-2-yl)thiazole; D007477:Ions; D008024:Ligands; D012996:Solutions; D013844:Thiazoles; D013876:Thiophenes; D014867:Water; D008628:Mercury