Open-shell chiral diradicals that feature both the unique chiroptical properties and tunable spin states have kindled numerous interests in organic synthesis and material science.We present a new class of such model s...Open-shell chiral diradicals that feature both the unique chiroptical properties and tunable spin states have kindled numerous interests in organic synthesis and material science.We present a new class of such model systems based on theπ-extended planar chiral pillar[5]arene derivatives P5Flu and P5Cz,where the pillar[5]arene-based chiral scaffolds are coupled with sterically encumbered fluorenyl and carbazolyl moieties as highly luminescent redox-active emitters,respectively.Both molecules in neutral states can readily undergo chemical oxidations leading toπ-conjugated chiral diradicals of the dehydrogenated P5Flu^(2·)and a positively charged dication P5Cz^(2+2)·.Characterization of the resulting Müller’s open-shell species by variable-temperature electron spin resonance(VT-ESR),UV-vis-NIR absorption,VT-NMR and by computational studies revealed a singlet(ΔE_(S-T)=-1.63 kcal mol^(-1))and a nearly degenerate singlet-triplet ground state(ΔE_(S-T)=0.05 kcal mol^(-1),with a diradical character index y0=0.89)for P5Cz^(2+2)·and P5Flu^(2·),respectively.We particularly show in this work a new journey for pillar[5]arenes from the conventionally available closed-shell structures to different open-shell spin states with potential applications in chirospintronics and NIR-active chiroptoelectronic materials.展开更多
基金supported by the National Natural Science Foundation of China(22471014,22271013)。
文摘Open-shell chiral diradicals that feature both the unique chiroptical properties and tunable spin states have kindled numerous interests in organic synthesis and material science.We present a new class of such model systems based on theπ-extended planar chiral pillar[5]arene derivatives P5Flu and P5Cz,where the pillar[5]arene-based chiral scaffolds are coupled with sterically encumbered fluorenyl and carbazolyl moieties as highly luminescent redox-active emitters,respectively.Both molecules in neutral states can readily undergo chemical oxidations leading toπ-conjugated chiral diradicals of the dehydrogenated P5Flu^(2·)and a positively charged dication P5Cz^(2+2)·.Characterization of the resulting Müller’s open-shell species by variable-temperature electron spin resonance(VT-ESR),UV-vis-NIR absorption,VT-NMR and by computational studies revealed a singlet(ΔE_(S-T)=-1.63 kcal mol^(-1))and a nearly degenerate singlet-triplet ground state(ΔE_(S-T)=0.05 kcal mol^(-1),with a diradical character index y0=0.89)for P5Cz^(2+2)·and P5Flu^(2·),respectively.We particularly show in this work a new journey for pillar[5]arenes from the conventionally available closed-shell structures to different open-shell spin states with potential applications in chirospintronics and NIR-active chiroptoelectronic materials.
