Optical Waveguiding Charge-Transfer Cocrystals: Examining the Impact of Molecular Rotations on Their Photoluminescence

High Resolution Image Download MS PowerPoint Slide Here, we present the first example of a binary optical waveguiding (OWG) cocrystal with large anisotropy featuring a fluorinated acceptor molecule (CPP-TFPN, 1 ) with on-plane rotational dynamics, confirmed by solid-state NMR ( 19 F T 1 ) and theoretical calculations. Spatially resolved microphotoluminescence and variable-temperature photoluminescence experiments allowed us to examine the OWG performance and photophysical properties of both single crystals and bulk microcrystalline samples. A comparison with an analogous cocrystal containing a regioisomeric acceptor (CPP-TFTN, 2 ) revealed that the photoluminescence characteristics of 1 are associated with the rotational motions of the acceptor, offering insights into how the molecular motion changes this property.