Syntheses, structures, two-photon absorption cross-sections and computed second hyperpolarisabilities of quadrupolar A–π–A systems containing E-dimesitylborylethenyl acceptors
作者:Christopher D. Entwistle、Jonathan C. Collings、Andreas Steffen、Lars-Olof Pålsson、Andrew Beeby、David Albesa-Jové、Jacquelyn M. Burke、Andrei S. Batsanov、Judith A. K. Howard、Jackie A. Mosely、Suk-Yue Poon、Wai-Yeung Wong、Fatima Ibersiene、Sofiane Fathallah、Abdou Boucekkine、Jean-François Halet、Todd B. Marder
DOI:10.1039/b905719f
日期:——
A series of bis(E-dimesitylborylethenyl)-substituted arenes, namely arene = 1,4-benzene, 1,4-tetrafluorobenzene, 2,5-thiophene, 1,4-naphthalene, 9,10-anthracene, 4,4â²-biphenyl, 2,7-fluorene, 4,4â²-E-stilbene, 4,4â²-tolan, 5,5â²-(2,2â²-bithiophene), 1,4-bis(4-phenylethynyl)benzene, 1,4-bis(4-phenylethynyl)tetrafluorobenzene and 5,5â³-(2,2â²:5â²,2â³-terthiophene), have been synthesised viahydroboration of the corresponding diethynylarenes with dimesitylborane. Their absorption and emission maxima, fluorescence lifetimes and quantum yields are reported along with the two-photon absorption (TPA) spectra and TPA cross-sections for the 5,5â²-bis(E-dimesitylborylethenyl)-2,2â²-bithiophene and 5,5â²-bis(E-dimesitylborylethenyl)-2,2â²:5â²,2â³-terthiophene derivatives. The TPA cross-section of the latter compound of ca. 1800 GM is the largest yet reported for a 3-coordinate boron compound and is in the range of the largest values measured for quadrupolar compounds with similar conjugation lengths. The X-ray crystal structures of 1,4-benzene, 2,5-thiophene, 4,4â²-biphenyl and 5,5â³-(2,2â²:5â²,2â³-terthiophene) derivatives indicate Ï-conjugation along the BCCâareneâCCB chain. Theoretical studies show that the second molecular hyperpolarisabilities, γ, in each series of compounds are generally related to the HOMO energy, which itself increases with increasing donor strength of the spacer. A strong enhancement of γ is predicted as the number of thiophene rings in the spacer increases.
一系列双(E-二甲基丁烯基苯基)取代的烯烃,即烯 = 1,4-苯、1,4-四氟苯、2,5-噻吩、1,4-萘、9,10-蒽、4,4â²-联苯、2、7-芴、4,4â²-E-二苯乙烯、4,4â²-甲苯、5,5â²-(2,2â²-二噻吩)、1,4-双(4-苯乙炔基)苯、1,4-双(4-苯乙炔基)四氟苯和 5,5â³-(2,2â²:5,5â³-(2,2â²: 5â²,2â³-四噻吩)的合成是通过相应的二乙炔基烯烃与二美辛基硼烷的硼氢化反应实现的。报告了它们的吸收和发射最大值、荧光寿命和量子产率,以及 5,5â²-双(E-二甲酰基丁烯基苯基)-2,2â²-噻吩和 5,5â²-双(E-二甲酰基丁烯基苯基)-2,2â²:5â²,2â³-四噻吩衍生物的双光子吸收(TPA)光谱和 TPA 截面。后一种化合物的 TPA 横截面约为 1800 GM,是迄今为止所报道的三配位硼化合物中最大的,也在具有类似共轭长度的四极化合物所测得的最大值范围内。1,4-苯、2,5-噻吩、4,4â²-联苯和 5,5â³-(2,2â²:5â²,2â³-四噻吩)衍生物的 X 射线晶体结构表明,Ï-共轭沿着 BCCâareneâCCB 链进行。理论研究表明,各系列化合物中的第二分子超极性δ³ 通常与 HOMO 能量有关,而 HOMO 能量本身会随着间隔物供体强度的增加而增加。预计随着间隔物中噻吩环数量的增加,δ³ 也会强烈增强。