1,3,2-Diazaborolyl-functionalized thiophenes and dithiophenes: synthesis, structure, electrochemistry and luminescence
作者:Lothar Weber、Vanessa Werner、Imme Domke、Hans-Georg Stammler、Beate Neumann
DOI:10.1039/b603365b
日期:——
Reaction of 2-bromo-1,3-diethyl-1,3,2-benzodiazaborole (1) with equimolar amounts of thienyl lithium or 2,2′-dithienyl lithium led to the generation of benzodiazaboroles 2 and 3 which are functionalized at the boron atom by a 2-thienyl or a 5-(2,2′-dithienyl) unit. Similarly 2-bromo-1,3-diethyl-1,3,2-naphthodiazaborole (4) and thienyl lithium or 2,2′-dithienyl lithium afforded the naphthoborolyl-substituted thiophene 5 or dithiophene 6. Treatment of 2,5-bis(dibromoboryl)-thiophene 7 with 2 eq. of tBuNCH–CHNtBu in n-hexane followed by sodium amalgam reduction of the obtained bis(diazaborolium) salt 8 gave the 2,5-bis(diazaborolyl)thiophene 9. The 2,5-bis(diazaborolidinyl)-thiophene 10 resulted from the cyclocondensation of 7 with 2 eq. of N,N′-di-tert-butylethylenediamine in the presence of NEt3. Analogously, cyclocondensation of 7 with N,N′-diethylphenylenediamine gave the bis(benzodiazaborolyl) functionalized thiophene 11. The novel compounds were characterized by elemental analysis and spectroscopy (1H-, 11B-, 13C-NMR, MS and UV-VIS). The molecular structure of 3 was elucidated by X-ray diffraction. Cyclovoltammograms show an irreversible oxidation wave at 298–598 vs. Fc/Fc+. The borolylated thiophenes and dithienyls show intense blue luminescence with Stokes shifts of 30–107 nm.
2-溴-1,3-二乙基-1,3,2-苯并二氮杂硼烯(1)与等摩尔的噻吩基锂或2,2′-二噻吩基锂反应,生成在硼原子上功能化的苯并二氮杂硼烯2和3,分别带有2-噻吩基或5-(2,2′-二噻吩基)单元。类似地,2-溴-1,3-二乙基-1,3,2-萘并二氮杂硼烯(4)与噻吩基锂或2,2′-二噻吩基锂反应,得到带有萘基硼烯取代的噻吩5或二噻吩6。将2,5-二(二溴硼基)-噻吩7与2倍摩尔的tBuNCH–CHNtBu在正己烷中反应,随后用钠合金还原所得到的双(二氮杂硼铵)盐8,得到2,5-二(二氮杂硼烯基)噻吩9。2,5-二(二氮杂硼啉基)噻吩10是7与2倍摩尔的N,N′-二叔丁基乙撑二胺在NEt3存在下的环缩合反应的产物。同样,7与N,N′-二乙基苯撑二胺的环缩合反应生成了双(苯并二氮杂硼烯基)噻吩11。新化合物通过元素分析和光谱学(1H-、11B-、13C-NMR、质谱和紫外-可见光)进行表征。化合物3的分子结构通过X射线衍射法确定。循环伏安图显示在298-598 mV vs. Fc/Fc+的不可逆氧化波。硼烯基噻吩和二噻吩表现出强烈的蓝色荧光,斯托克斯位移为30-107 nm。