Tunable Multicolor Circularly Polarized Luminescence via Co-assembly of One Chiral Electron Acceptor with Various Donors

Abstract

Chiroptical materials with multicolor and sign-invertible circularly polarized luminescence (CPL) are important for advanced optical devices and display technologies. Here, a general strategy is developed to generate CPL with highly tunable emission bands and handedness through charge-transfer (CT) complexation and co-assembly of one chiral non-emissive tetranitrofluorene-based acceptor with various achiral purple to blue emissive donors. The resulting assemblies exhibit intense CPL with a rich array of colors (519–668 nm) and prominent dissymmetry factors (|glum|) in the range of 10−3–10−2. Notably, the CPL sign can be readily inverted by slightly changing the molecular structure of achiral donors. Single-crystal analysis reveals that the donor and acceptor molecules are alternately and asymmetrically packed in a lamellar fashion through CT interactions, leading to efficient transfer of chirality. Furthermore, the refined packing is mediated by the intensity and manner of CT interactions, rendering an inversion of chirality. The chiral co-assembly not only occurs for planar achiral donor molecules, but is also accessible to nonplanar conjugated molecules such as [4]helicene derivatives. Thus, the CPL feature of the resulting products can be easily and broadly manipulated, aiming at advanced chiroptical systems.