A fluorescence probe based on 6-phenylimidazo[2,1-b]thiazole and salicylaldehyde for the relay discerning of In3+ and Cr3+†
A new fluorescence probe, (E)-N′-(2-hydroxybenzylidene)-6-phenylimidazo[2,1-b]thiazole-3-carbohydrazide (LB1), based on 6-phenylimidazo[2,1-b]thiazole and salicylaldehyde was designed and synthesized. The chemical structures of LB1 and its intermediate were characterized via1H NMR, 13C NMR, FTIR, and mass spectrometry. The LB1 probe exhibited high sensitivity and selectivity towards In3+ and Cr3+via a fluorescence ‘off–on–off’ response. The detection limits of In3+ and Cr3+ were 2.59 × 10−9 M and 8.05 × 10−7 M, respectively. The LB1 probe demonstrated ideal selectivity for In3+ among other competing ions and the newly formed complex [LB1 + In3+] could be further used as a new fluorescence platform towards Cr3+. The Job Plot of LB1 towards In3+ and Cr3+ was 1 : 1 and this was supported by mass spectrometry. The plausible binding modes and mechanisms were determined through DFT/TDDFT calculations using Gaussian 09.