Nanomolar Detection of Al(III) Ion by Hydrazones Carrying Benzothiazole and Substituted Phenol Groups

A Fluorescent Probe Based on the Hydrazone Schiff Base for the Detection of Zn2+ and its Application on Test Strips

A novel fluorescent probe SHK for Zn²⁺ detection was designed based on the hydrazone Schiff base, successfully synthesized by Suzuki coupling and condensation reactions. The probe SHK in DMSO/H₂O showed extremely weak fluorescence. However, the solution exhibited an intensive yellow-green emission with the introduction of Zn²⁺. In contrast, negligible fluorescence change was observed when other metal ions were added, suggesting a high selectivity of SHK for Zn²⁺ detection. The Job's Plot analysis revealed that a 1:1 stoichiometric adduct SHK-Zn²⁺ formed during the Zn²⁺ sensing. The binding constant of the complex was determined to be 184 M^- 1, and the detection limit for Zn²⁺ was calculated to be 112 µM. Moreover, the probe SHK achieved selective fluorescence sensing for Zn²⁺ on test strips, which guaranteed its practical application prospect.

Crystal structure of (E)-4-bromo-N′-(3-chloro-2-hydroxybenzylidene)benzohydrazide, C14H10BrClN2O2

C14H10BrClN2O2, orthorhombic, Pca21 (no. 29), a = 32.4137(12) Å, b = 4.6683(2) Å, c = 8.8873(3) Å, V = 1344.80(9) Å3, Z = 4, R gt (F) = 0.0239, wR ref (F 2) = 0.0611, T = 150(2) K.

Expected and unexpected products of reactions of 2-hydrazinylbenzo-thia-zole with 3-nitro-benzene-sulfonyl chloride in different solvents

The syntheses and crystal structures of 2-[2-(propan-2-yl-idene)hydrazin-yl]-1,3-benzo-thia-zol-3-ium 3-nitro-benzene-sulfonate (C10H12N2S+·C6H4NO5S-), (I), 2-[2-(3-nitro-benzene-sulfon-yl)hydrazin-yl]-1,3-benzo-thia-zole (C13H10N4O4S2), (II) and 2-[2-(3-nitro-benzene-sulfon-yl)hydrazin-yl]-1,3-benzo-thia-zol-3-ium 3-nitro-benzene-sulfonate (C13H11N4O4S2+·C6H4NO5S-), (III) are reported. Salt (I) arose from an unexpected reaction of 2-hydrazinylbenzo-thia-zole with the acetone solvent in the presence of 3-nitro-benzene-sulfonyl chloride, whereas (II) and (III) were recovered from the equivalent reaction carried out in methanol. The crystal of (I) features ion pairs linked by pairs of N-H⋯Os (s = sulfonate) hydrogen bonds; adjacent cations inter-act by way of short π-π stacking inter-actions between the thia-zole rings [centroid-centroid separation = 3.4274 (18) Å]. In (II), which crystallizes with two neutral mol-ecules in the asymmetric unit, the mol-ecules are linked by N-H⋯N and N-H⋯On (n = nitro) hydrogen bonds to generate [[Formula: see text]1[Formula: see text]] chains, which are cross-linked by C-H⋯O and π-π stacking inter-actions. The crystal of (III) features centrosymmetric tetra-mers (two cations and two anions) linked by cooperative N-H⋯O hydrogen bonds; C-H⋯O and π-π inter-actions occur between tetra-mers.