Bing-guang Zhang

Conformational switching fluorescent chemosensor for chloride anion

A new fluorescent “off–on” signaling chemical sensor with high selectivity for chloride anion through a guest-induced conformational switching process was achieved by using a positively charged tripodal receptor with naphthyl groups attached to the benzoimidazolium arms.

A highly selective fluorescent sensor for fluoride through ESPT signaling transduction

A highly selective fluorescent sensor for fluoride, bis(2-hydroxy-1-naphthaldehyde)-2,6-pyridinedicarboxylic acid hydrazone (H-NP1) was synthesized and structurally characterized. UV-Vis and luminescent titrations of H-NP1 with F− demonstrated the presence of an H-NP1⋯F− interaction species with association constant log K# = 5.26 ± 0.01. The sensor responded to fluoride ion through an excited-state intermolecular proton transfer (ESPT) mechanism with the emission band red-shifted and enhanced. For further studying the potential mechanism, binding-signaling transduction of related compound H-NP2, bis(2-hydroxy-1-naphthaldehyde)-1,3-benzenedicarboxylic acid hydrazone and two control compounds (H-NP3) and (H-NP4) derived from 1-naphthaldehyde was also investigated for comparison.

Naked-eye detection of fluoride ion in water: a remarkably selective easy-to-prepare test paper

A test paper for high-selectivity detecting fluoride ion in natural aqueous environments without any spectroscopic instrumentation was achieved by using Ru-bipy based quinonehydrazone as a chromo- and fluorogenic hybrid chemosensor.

Anion induced binding electrochemical signal transduction in ferrocenyl benzolimidazolium podands

Benzene-based bipodal and tripodal electrochemical-responsive receptors with ferrocenyl arms comprising benzoimidazolium moieties were synthesized and structurally characterized. The two-arm para compound 1·2Br exhibited a cisoid conformation with the two ferrocene moieties positioned in the same side and a templating bromide anion sited inside. The cisoid form was stabilized not only by the (C–H)+⋯Br− hydrogen bond, but also cooperated by the C–H⋯Br− hydrogen bonding related to the Cp rings of the ferrocenyl moieties and the CH2 groups, respectively. The association constants of the receptor 1 for Cl−, Br− and I− were determined using 1H NMR titration in d6-DMSO as 600 M−1, 440 M−1 and 350 M−1, respectively. The meta three-arm compound 2·3Br adopted a cone conformation with a bromide anion sited inside the molecular cavity and three ferrocene-containing arms positioned on the same side. The cationic heterocycle interacted with the bromide anion through the three-fold C–H⋯Br− hydrogen bonding. 1H NMR titrations in d6 DMSO revealed that the association constants of 2 for Cl−, Br− and I− were 9.7 × 103 M−1, 6.8 × 103 M−1 and 120 M−1, respectively. Electrochemical measurements demonstrated that directed hydrogen bonding between the ferrocenyl moiety and the anion was important for the two-arm receptor 1 exhibiting more efficient binding electrochemical signal transduction.