Symmetry‐Breaking Directed Assembly in Achiral Point Groups for Circularly Polarized Room‐Temperature Phosphorescence

Very recently, considerable attention has been given to pure organic circularly polarized room-temperature phosphorescent (CP-RTP) materials due to their unique photophysical properties. However, the directed construction of optically active phosphorescent signals within achiral systems remains a formidable challenge. In this study, two achiral crystals, 2CN4S and 2F4S, belonging to the achiral point groups 2/m and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics><mml:mover><mml:mn>1</mml:mn> <mml:mo>¯</mml:mo></mml:mover> <mml:annotation>$\bar{1}$</mml:annotation></mml:semantics> </mml:math> , exhibit strong CP-RTP emission with high photoluminescence dissymmetry factors (g_lum) up to 5.5 × 10^-2 (543 nm) and 4.3 × 10^-2 (550 nm), respectively. This phenomenon is attributed to the intrinsic mirror-antiparallel molecular conformations induced by the targeted substitution of cyano/fluoro groups, which spontaneously assemble into symmetry-breaking helical superstructures through synergistic C─H···N hydrogen bonding and π-π interactions. This work not only establishes a novel approach for CP-RTP material design but also overcomes structural constraints in optically active materials within achiral point group systems.