Multicolor conjugated polymers containing thiophene/indole moieties and the influence of structures on their photophysical properties

A series of new monomers (M1-M6) containing both thiophene and indole structures and carrying different substituents with varied electronic effects on the 2,3-position of indole have been designed and synthesized. The corresponding conjugated polymers (P1-P6) obtained via oxidative polymerization presented different spectral phenomena and fluorescence properties as well as fluorescence lifetime due to the synergistic influence of varied electronic effects, the interaction between polymer chains and pi-pi stacking of indole moieties. By adjusting the properties of substituents and their position in indole ring, these as-prepared conjugated polymers can emit fluorescence with varied colors such as blue-green, yellow, orange-red, brown red, light red and red, and show the changes of fluorescence intensity in different degrees with the increase of 365 nm UV irradiation time. Among them, P3 and P5 show much stronger fluorescence than other species, which is very desirable for application.