A Highly Selective and Sensitive Fluorescent Turn-Off Probe for Al3+ Based on Polypyrimidine

The polyfluorene copolymers with different pyrimidine content has been synthesized and characterized by 1HNMR, 13CNMR and FT-IR spectrum. The aggregation, acidochromicity, and metallochromicity of copolymers has been investigated. The pyrimidine content of polymer has great affect in acidochromic properties for methanesulfonic acid (MSA) and selectivity for Al3+. The colour change of copolymer/Al3+ complexes can be detected by the naked eye. The copolymers are found to be good linearly proportional to the concentration of Al3+ ions in a range from 1.0×10-6 to 1.0×10-3 M with a detection limit of 1.895×10-8 M. The binding constant of the copolymer/Al3+ complexes was calculated using Benesi-Hildebrand equation and was found to be 8.95×105 M-1. The XPS spectroscopy, SEM micrograph and the EDS analysis reveal that the metal ion coordination occurs on the pyrimidine ring in the copolymers. This copolymer will be widely used for detection of protons and metals as fluorescent sensors.