Topology-Directed\nSynthesis of Helical Phosphoniums\nwith High Diradical Character and Polar-Dependent Electron Transfer

Molecular topology synthesis of polycyclic aromatic hydrocarbons\n(PAHs) with diradical character takes root in intramolecular coupling\nbreakthrough. Herein, we report selective Mn(III)/Cu(II)-mediated\nC–P and C–H bond cleavage to obtain robust donor-fused\nphosphoniums with helical or planar geometries and distinct cationic\ncharges. The former helical structures incorporate a common phospha[5]helication\nacceptor and different arylamine donors, and the latter planar structure\ncontains a phospha[6]dication and the same donors. These unprecedented\nionic salts hold distinguishing donor–acceptor (D–A)\nconstructions, showing unique topology-dependent optoelectronic properties.\nThe folded helical radical ammoniums possess an extreme electron-deficient\nstate and through-space isolation with high diradical character (<i>y</i><sub>0</sub> = 0.989). Moreover, the tunable charge transfer\n(CT) and locally excited (LE) transition components facilitate diverse\nhybridized local and charge transfer (HLCT) in different solvents,\nendowing the highest emission band gap variation of 0.78 eV (∼217\nnm). The fluorescence radiation could also be adjusted from blue to\nnear-infrared regions via topology tailoring and polar-dependent excited\nstates, which could output additional circularly polarized luminescence\nin a compatible chiral menthol matrix with elevated quantum efficiency\nand an undisturbed deep-red glow. It is worth mentioning that an atomically\nprecise Mn(III) halide has been unprecedentedly captured and determined\nfor C–P bond activation.