Syntheses of rod-shaped fluorescent 1,3,2-benzodiazaboroles with phosphonium, and phosphane chalcogenide acceptor functions
作者:Lothar Weber、Henry Kuhtz、Lena Böhling、Andreas Brockhinke、Anna Chrostowska、Alain Dargelos、Audrey Mazière、Hans-Georg Stammler、Beate Neumann
DOI:10.1039/c2dt30666b
日期:——
A series of 1,4-phenylenes X-C6H4-BDB with a 1,3,2-benzodiazaborolyl (BDB) and a phosphorus based end group [X = PPh2 (2), P(O)Ph2 (3), P(S)Ph2 (4), P(Se)Ph2 (5), P(AuCl)Ph2 (6) and P(Me)Ph2 (7)] as well as 2-(2′)thienyl-1,3,2-benzodiazaboroles with a second end group X [X = PPh2 (8), P(S)Ph2 (9), P(Se)Ph2 (10) and P(Me)Ph2 (11)] in the 5′ position were synthesised using established methodologies. Molecular structures of 2–9 and 11 were determined by X-ray diffraction. Compounds 3, 4, 6, 7, 9 and 11 show intense blue luminescence in cyclohexane, toluene, chloroform, dichloromethane and tetrahydrofuran with pronounced solvatochromism. Thereby Stokes shifts in the range of 8950–10 440 cm−1 and quantum yields up to 0.70 were observed in dichloromethane solutions. In contrast to this, for the selenides 5 and 10 quantum yields are small (<0.1). The absorption maxima (298–340 nm) are well reproduced by TD-DFT computations (B3LYB/G-311G(d,p)) and arise from strong HOMO–LUMO transitions. With the exception of 5 and 10 the HOMOs of the molecules under study are mainly located on the benzodiazaborole group. In 5 and 10 the HOMOs are on the selenium atoms. The LUMOs of all new neutral molecules are mainly represented by the phenylene or thiophene bridge. In the phosphonium cations the LUMOs have additional contributions from the phosphonium unit.
合成了一系列的1,4-芳烃X-C6H4-BDB,具有1,3,2-苯并二氮硼烷 (BDB) 和基于磷的末端基团[X = PPh2 (2), P(O)Ph2 (3), P(S)Ph2 (4), P(Se)Ph2 (5), P(AuCl)Ph2 (6) 和 P(Me)Ph2 (7)],以及在5'位的2-(2')噻吩基-1,3,2-苯并二氮硼烷,具有第二个末端基团X [X = PPh2 (8), P(S)Ph2 (9), P(Se)Ph2 (10) 和 P(Me)Ph2 (11)]。这些化合物是使用已建立的方法合成的。通过X射线衍射确定了化合物2–9和11的分子结构。化合物3、4、6、7、9和11在环己烷、甲苯、氯仿、二氯甲烷和四氢呋喃中展现出强烈的蓝色发光,且具有显著的溶剂变色效应。因此,在二氯甲烷溶液中观察到了8950–10,440 cm−1的斯托克斯位移和高达0.70的量子产率。相比之下,硒化物5和10的量子产率较小 (<0.1)。吸收峰(298–340 nm)通过TD-DFT计算(B3LYB/G-311G(d,p))得到了良好的再现,并源于强烈的HOMO–LUMO跃迁。除了5和10外,所研究分子的HOMO主要位于苯并二氮硼烷基团上。在5和10中,HOMO位于硒原子上。所有新的中性分子的LUMO主要由芳烃或噻吩桥表示。在磷鎓阳离子中,LUMO还来自磷鎓基团的额外贡献。