Thiophene appended schiff base probe for selective ‘turn-on’ response for copper (ii) ion and their applications in live cell imaging

In this research, we have synthesized a thiophene Schiff base from 5-phenyl thiophene-2-carboxaldehyde and 2-thiophene carboxylic acid hydrazide and characterized by using FT-IR NMR , HRMS and SC-XRD analysis techniques. The probe exhibited a selective turn-on fluorescence response for Cu 2+ over 20 other common metal ions in a CH 3 CN (9:1, v/v) solution. The Job’s plot represents a 1:1 binding complexation mode and further DFT study was carried out to aid in understanding the geometric structure and interaction of the ligand and Cu 2+ . The detection limit (LOD) and limit of quantification (LOQ) were found to be 20 nM and 69 nM respectively. Furthermore, the probe’s sensing ability was tested in HeLa cells and their fluorescence imaging also supported the effective turn-on response towards Cu 2+ ion. • A thiophene appended Schiff base was synthesized and confirmed by using FT-IR, NMR, HRMS and SC-Xrd analysis techniques. • The probe exhibited a selective turn-on fluorescence response for Cu 2+ over 20 other metal ions in CH 3 CN:H 2 O solution. • By using job’s plot, FT-IR titration and DFT studies, the development of Cu 2+ complex was demonstrated. • The limit of detection (LOD) and limit of quantification (LOQ) were found to be 20 nM and 69 nM respectively. • In the presence of Cu 2+ ions, fluorescence imaging in living HeLa cells has shown that the probe is biocompatible.