Circularly polarized luminescence of polymers with coil to helix transformation in water system triggered via metal coordination

Abstract

Circularly polarized luminescence (CPL) of conjugated polymers is promising functional materials for a wide range application, particularly in the field of chiral optoelectronic devices. It is critical yet challenging to endow these materials against varied environment change, such as polarity of water, due to the destruction of the induced helicity of conjugated polymers by water hydrogen bonding. In this contribution, a series of aqueous phase CPL-active materials are constructed through the synergistic effect of hydrogen bonding and metal coordination. The fluorescent random coil amino acid-based poly( N -propargylamide) exhibiting obvious CD and CPL effects are induced by metal ions in aqueous solution. The conformational transition from coil to helix and the CPL performance are distinctly depicted via the CD, CPL signals and noticeably red-shifted UV–vis absorption. Moreover, the luminescence dissymmetry factor (| g lum |) values of the induced helical polymers were up to 8.07 × 10 −3 and 2.73 × 10 −2 , respectively, in aqueous solution and thin films. It was found that the successful induction of aqueous phase CPL-active polymer attribute to chiral amplification and aggregation-enhanced emission (AEE) effect of contracted cis-cisoidal helical main chain. These results indicated a general and simple approach for the construction of aqueous phase CPL materials, and a possible relationship between geometric structure of helical conformation and the CPL-activity induction of optically inactive polymers are simultaneously established. This contribution broadens practically chiroptical applications of CPL materials in water environment and enriches the synthetic types of CPL materials. • The CPL-active polymer based on cis-cisoid helix in aqueous solution and thin films states is prepared. • The | g lum | value of the prepared polymer in aqueous solution and films are as high as to 8.07 × 10 −3 and 2.73 × 10 −2 , respectively. • The successful trigger of CPL-activity attribute to chiral amplification and aggregation-enhanced emission (AEE) effect of one-handed helical structure.