Influence of polymer conformations on the aggregation behaviour of alternating dialkylsilylene-[4,4′-divinyl(cyanostilbene)] copolymers

The influence of the substituents at silicon on the aggregation enhanced emission (AEE) of alternating dialkylsilylene-[4,4'-divinyl(cyanostilbene)] copolymers 3 and 4 is examined. The presence of the bulky isopropyl group in 3b significantly enhances the quantum yield upon aggregation. On the other hand, the emission intensity of the methyl-substituted polymer 3a is only slightly enhanced under the same conditions. The bulky isopropyl substituents on silicon may exert the Thorpe-Ingold effect on these copolymers resulting in conformation difference, which may dictate the nature of the aggregation between polymers, and hence, the photophysical behaviour of these polymers.