Linear Axially Chiral Conjugated Polymers Exhibiting Ultralong Low-Temperature Phosphorescence and Intense Circularly Polarized Luminescence

Ultralong organic phosphorescence (UOP) and circularly polarized luminescence (CPL), as two important branches in the field of organic optical functional materials have broad prospects. In this work, a pair of novel conjugated polymers with low-temperature UOP and intense CPL properties are constructed by incorporating rigid axially chiral chromophores into a polymeric backbone. The twisted and rigid biphenyl skeleton not only effectively reduces the energy gap between the S-1 and T to greatly facilitate the intersystem crossing process, but also suppress the non-radiative decay from T-1 to S-0. As a result, a strong and ultralong afterglow of up to 33 s is achieved in 2-MeTHF at 77 K. Moreover, the repeating rigid biphenyl skeleton with its helix-like form also promotes the chiroptical activity of the polymers, and intense signals are shown in the low-temperature CPL spectra with absolute g(lum) values of 9.7x10(-3) and 5.8x10(-3) at the fluorescence and phosphorescence emission peaks, respectively. This work represents the first low-temperature materials with UOP and CPL properties, which provides a new guideline and perspective for the development of persistent luminescence materials.

Automated summary

In this study, a pair of novel conjugated polymers with low-temperature ultralong organic phosphorescence (UOP) and intense circularly polarized luminescence (CPL) properties were constructed by incorporating rigid axially chiral chromophores into a polymeric backbone. The twisted and rigid biphenyl skeleton effectively reduces the energy gap between the excited singlet and triplet states, resulting in a strong and ultralong afterglow. The repeating rigid biphenyl skeleton also promotes the chiroptical activity of the polymers, leading to intense CPL signals in the low-temperature spectra.