Topology-Directed Synthesis of Helical Phosphoniums with High Diradical Character and Polar-Dependent Electron Transfer

Molecular topology synthesis of polycyclic aromatic hydrocarbons (PAHs) with diradical character takes root in intramolecular coupling breakthrough. Herein, we report selective Mn(III)/Cu(II)-mediated C–P and C–H bond cleavage to obtain robust donor-fused phosphoniums with helical or planar geometries and distinct cationic charges. The former helical structures incorporate a common phospha[5]helication acceptor and different arylamine donors, and the latter planar structure contains a phospha[6]dication and the same donors. These unprecedented ionic salts hold distinguishing donor–acceptor (D–A) constructions, showing unique topology-dependent optoelectronic properties. The folded helical radical ammoniums possess an extreme electron-deficient state and through-space isolation with high diradical character (y0 = 0.989). Moreover, the tunable charge transfer (CT) and locally excited (LE) transition components facilitate diverse hybridized local and charge transfer (HLCT) in different solvents, endowing the highest emission band gap variation of 0.78 eV (∼217 nm). The fluorescence radiation could also be adjusted from blue to near-infrared regions via topology tailoring and polar-dependent excited states, which could output additional circularly polarized luminescence in a compatible chiral menthol matrix with elevated quantum efficiency and an undisturbed deep-red glow. It is worth mentioning that an atomically precise Mn(III) halide has been unprecedentedly captured and determined for C–P bond activation.