Triple para-Functionalized Cations and Neutral Radicals of Enantiopure Diaza[4]helicenes
Bibiana Fabri,
Tiziana Funaioli,
Lucas Frédéric
et al.
Abstract:Modulation of absorbance and emission is key for the design of chiral chromophores. Accessing a series of compounds absorbing and emitting (circularly polarized) light over a wide spectral window and often toward near-infrared is of practical value in (chir)optical applications. Herein, by late-stage functionalization on derivatives bridging triaryl methyl and helicene domains, we have achieved the regioselective triple introduction of para electron-donating or electron-withdrawing substituents. Extended tunin… Show more
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 (y
0 = 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.
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 (y
0 = 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.
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