Photocharacterization and pH Sensing Properties of a Novel Synthesized Fluorescent Schiff Base Derivative

Abstract

Design and synthesis of different, highly sensitive and fast response fluorescent materials are very important in the development of pH sensors. In this study, a new pH-sensitive Schiff-base ligand (PHS1) was synthesized by the condensation reaction of newly synthesized 1,3,4-thiadiazole derivative containing phenanthroimidazole (PHT1) with 3,5-ditertbutylsalicylaldehyde (1:1) in ethanol. The molecular structure was confirmed by structural characterization methods. The absorption and fluorescence properties of PHS1 were investigated in DMSO to determine the photocharacterization properties. Then, PHS1 was investigated as a fluorescent pH sensor. UV absorption and emission studies of PHS1 with varying pH (at pH=2.0, 4.0, 6.0, 8.0, 10.0 and 12.0) were determined in Britton-Robinson buffer. The absorption wavelength recorded at 345 nm at pH 2.0 showed bathochromic effect as pH increased (at pH= 4.0; 6.0 and 8.0). At pH 10.0 and 12.0, PHS1 showed two absorption peaks at 357 nm and a new low energy absorption band at 405 nm. The fluorescence spectrum of PHS1 showed a red shift with an increasing wavelength from 439 nm to 473 nm between pH=2.0 and 12.0. These results showed that PHS1 is sensitive to pH change in acidic and basic environments.