Film sensor for Zn2+ ion via self-assembled monolayer of receptor on quartz plate surfaces

Fluorescent self-assembled monolayers (SAMs) on hydrophilic oxide surfaces are developed as new sensing materials for metal ions. This fluorescent film sensor was designed and prepared by chemically immobilization of a terminal silane group of monomer molecule onto SAM on quartz plates and was used for detection of Zn2+ ion in MeOH solvent. The advantages of this technique have been demonstrated experimentally by the sensitive response of the presence of small amount of Zn2+ (DL = 1.7 × 10−5 mol L−1). Optical spectroscopy study of the film showed that strong interactions occur between the receptor molecule and Zn2+. In the presence of Zn2+, the position λmax of the film shifts from 405 nm to 365 nm. Also, the film emission intensity is increased at 486 nm due to intra-molecular charge transfer (ICT) in the excited state of the receptor while the other transition metal ions showed little or no interaction. The sensitive response and interference free of the sensing process make the film a promising Zn2+-sensor.