Nucleobase-Functionalized Conjugated Polymer for Detection of Copper(II)

In recent years, supramolecular organization of thiophene derivatives, oligo- and polythiophene, have been developed with various designs to achieve complex functions. Here, we describe the synthesis and characterization of a conjugated polymer with thymidine side chain bases and polythiophene backbones (PTT) instead of phosphate bonds in DNA, and the PTT exhibits exceptional fluorescence quenching efficiency upon binding of Cu2+ ions in aqueous medium, which is suggested to be electron transfer from the pi* orbit at the excited state of PTT to the 3d orbit of Cu2+ ions and subsequent Cu2+-mediated interpolymer pi-stacking aggregation. Furthermore, Cu2+ ions can be selectively and easily monitored by the fluorescence quenching of PTT, which can be used for detection of Cu2+ ions with good selectivity and high sensitivity in aqueous medium. Both experimental and theoretical methods have been devoted to demonstrate the strong affinity and steric interaction of PTT toward Cu2+. These findings will illustrate new directions for the design of nucleobase-functionalized materials with transition metals responsive activity.