Synthesis of novel azo linkage-based Schiff bases including anthranilic acid and hexanoic acid moieties: investigation of azo-hydrazone and phenol-keto tautomerism, solvatochromism, and ionochromism


TURKISH JOURNAL OF CHEMISTRY, vol.43, no.1, pp.266-299, 2019 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 43 Issue: 1
  • Publication Date: 2019
  • Doi Number: 10.3906/kim-1807-24
  • Page Numbers: pp.266-299


Two new azo-Schiff base receptors (L-1 and L-2) containing azo and azomethine groups with a conjugated group (benzyl ring of anthranilic acid, in L-1) and electron-donating group (alkyl chain of hexanoic acid, in L-2) were synthesized and characterized. Azo-hydrazone/phenol-keto tautomerism and solvatochromism were investigated. Studying their sensing ability towards cations (Co2+, Cu2+, Zn2+, Ni2+, Pb2+, Cd2+, Mn2+, Fe3+, Cr3+, and Al3+) high sensitivity and selectivity were recorded for Fe3+ by naked eye and UV-Vis spectra in DMF-aqueous HEPES buffer (v:v, 1:1, pH 6.8). The color of L-1 and L-2 solutions instantly changed from yellow to deep orange and pale orange. L-2 sensed Cu2+ and Al3+ ions selectively by UV-Vis spectra. The interactions of receptors with F-,Cl-, CH3COO-, C2O42-, H2PO4-, and OH- anions were also investigated in DMF-HEPES 1:1 and 4:1 solvent mixtures. L-1 sensitively responded to anions according the order of OH- >C2O42- >F- in the 1:1 mixture and OH->F- >CH3COO- >C2O42- in the 4:1 mixture in UV-Vis spectra with color changing from pale yellow to dark yellow. However, L-2 showed weak spectral changes in the UV-Vis spectra, so its sensitivity was poorer than L-1, attributed to the effect of alkyl chains.