Double Protonation of 1,5-Bis(triarylaminoethynyl)anthraquinone To Form a Paramagnetic Pentacyclic Dipyrylium Salt
Double Protonation of 1,5-Bis(triarylaminoethynyl)anthraquinone To Form a Paramagnetic Pentacyclic Dipyrylium Salt
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DOI：
10.1021/ja105250f
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发表时间：
2010-09-08
影响因子：
15
通讯作者：
Nishihara, Hiroshi
中科院分区：
文献类型：
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作者：
Rao, Koya Prabhakara;Kusamoto, Tetsuro;Nishihara, Hiroshi
分别实现了新的给体（D）-受体（A）和D-A-D共轭分子1-三芳氨基乙炔基蒽醌（1-AmAq）和1，5-双（三芳氨基乙炔基）蒽醌（1，5-Am（2）Aq）的质子化诱导分子内环化反应。前者与二（三氟甲砜）亚胺酸（TFSIH）发生单质子化反应，得到吡喃盐[1-AmPyl]TFSI，后者经过新型的双质子环化反应，得到具有新的五环骨架的1，5-二（三芳氨基）二吡喃盐[1，5 Am（2）Pyl（2）]（TFSI）（2）。该二价阳离子盐可以被还原以得到中性物质2，8-双（三芳基氨基）苯并[de]异色烯并[1，8-gh]色烯（[1，5-Am（2）Pyl（2）]（0）），其保持平面五环骨架。由于HOMO-LUMO能隙非常窄，所得到的稠环化合物显示出独特的光学、电化学和磁性。特别地，双阳离子[1，5-Am（2）Pyl（2）]（2+）通过与五环骨架的价互变异构而显示出以两个三芳基胺部分为中心的两个自旋的顺磁性行为。
Protonation-induced intramolecular cyclization reactions of new donor (D)-acceptor (A) and D-A-D conjugated molecules 1-triarylaminoethynylanthraquinone (1-AmAq) and 1,5-bis(triarylaminoethynyl)anthraquinone (1,5-Am(2)Aq), respectively, were achieved. The former undergoes monoprotonation with bis(trifluoromethanesulfone)imide acid (TFSIH) to give pyrylium salt [1-AmPyl]TFSI, whereas the latter undergoes a novel double proton cyclization reaction to yield 1,5-bis(triarylamino)dipyrylium salt [1,5Am(2)Pyl(2)](TFSI)(2) with a new pentacyclic backbone. This divalent cationic salt can be reduced to give the neutral species 2,8-bis(triarylamino)benzo[de]isochromeno[1,8-gh]chromene ([1,5-Am(2)Pyl(2)](0)), which maintains the planar pentacyclic backbone. The obtained condensed-ring compounds show unique optical, electrochemical, and magnetic properties due to the extremely narrow HOMO-LUMO gap. In particular, the dication [1,5-Am(2)Pyl(2)](2+) shows paramagnetic behavior with two spins centered on two triarylamine moieties through valence tautomerization with the pentacyclic backbone.