Elusive Antimony‐Centered Radical Cations: Isolation,Characterization, Crystal Structures,and Reactivity Studies

One‐electron oxidation of the stibines Aryl₃Sb ( 1 , Aryl=2,6‐ⁱ Pr₂‐4‐OMe‐C₆H₂; 2 , Aryl=2,4,6‐ⁱ Pr₃‐C₆H₂) with AgSbF₆ and NaBAryl^F₄ (Aryl^F=3,5‐(CF₃)₂C₆H₃) afforded the first structurally characterized examples of antimony‐centered radical cations 1 ^.+[BAryl^F₄]⁻ and 2 ^.+[BAryl^F₄]⁻. Their molecular and electronic structures were investigated by single‐crystal X‐ray diffraction, electron paramagnetic resonance spectroscopy (EPR) and UV/Vis absorption spectroscopy, in conjunction with theoretical calculations. Moreover, their reactivity was investigated. The reaction of 2 ^.+[BAryl^F₄]⁻ and p ‐benzoquinone afforded a dinuclear antimony dication salt 3 ²⁺[BAryl^F₄]₂⁻, which was characterized by NMR spectroscopy and X‐ray diffraction analysis. The formation of the dication 3 ²⁺ further confirms that the isolated stibine radical cations are antimony‐centered.     

Hybrid Chloroantimonates(III): Thermally Induced Triple‐Mode Reversible Luminescent Switching and Laser‐Printable Rewritable Luminescent Paper

Two hybrid chloroantimonates(III), [Bzmim]₃SbCl₆ ( 1 , Bzmim=1‐benzyl‐3‐methylimidazolium, T_m1=410 K) and [Bzmim]₂SbCl₅ ( 2 , T_m2=348 K) are presented. 1 exhibits green emission (quantum efficiency of 87.5 %); 2 exhibits blue and red emissions under the irradiation of 310 and 396 nm light, respectively. Using different cooling methods, crystalline 1 and IL@2 (IL=ionic liquid of [Bzmim]Cl) could be generated from the molten 1 . Reversible structural and PL transformation triggered by moisture or heat was observed between 1 and IL@2 . Such PL switching, combined with the crystallization‐induced PL properties of 1 and 2 , resulted in the firstly reported triple‐mode reversible PL switching, that is, on–off (T>T_m1), color switching (T<T_m2), and on–off–on (T_m2<T<T_m1). Furthermore, ink‐ and mask‐free laser‐printable rewritable PL paper was achieved. This study demonstrates the promise of dynamic insertion/extraction of ILs in hybrid chloroantimonates for anti‐counterfeiting and rewritable PL paper.