Novel two-photon absorption (TPA) chromophores that contain spirofluorene and ladder-type pentaphenylenes (LPPs) as π-centres with diarylamine groups as electron donors (D) in the D–π–D arrangement are prepared. The spirofluorenes with different donors at the both terminals exhibit TPA activity increase as the donor strength increases (from N-ethylcarbazoyl 1, triphenylamino 2, to N,N-dibutylaminophenyl 3). Compared to the spirofluorene derivatives, the LPP derivatives show the larger TPA efficiency due to better coplanarity throughout the molecule. As the LPP unit added from single (4), double (5), to triple (6), the increment of the TPA cross-section exceeds the one-fold of a LPP unit, which can be attributed to the cooperative enhancement of the TPA cross-section (σ2) between the LPP units. We have also explored the effect of introducing charge defects and examined the resonance enhancement by chemical oxidation on the TPA properties of LPP derivatives 4 and 5. Nearly an order of magnitude enhancement was found in the TPA cross-section of dye 4, which was interpreted as the role of charge transfer from LPP π-centre to the cationic diarylamine end groups.
本研究制备了新型双光子吸收(
TPA)发色团,这些发色团以螺
芴和梯形五苯(LPPs)为π中心,以二芳基胺基团为电子供体(D),呈 D-π-D 排列。随着供体强度的增加(从 N-ethylcarbazoyl 1、triphenylamino 2 到 N,N-dibutylaminophenyl3),两端具有不同供体的螺
芴的
TPA 活性也随之增加。与螺
芴衍
生物相比,LPP 衍
生物的
TPA 效率更高,这是因为整个分子的共面性更好。随着 LPP 单元从单(4)、双(5)到三(6)的增加,
TPA 横截面的增量超过了一个 LPP 单元的 1 倍,这可归因于 LPP 单元间
TPA 横截面(σ2)的协同增强。我们还探讨了引入电荷缺陷的影响,并研究了
化学氧化对 LPP 衍
生物 4 和 5 的
TPA 特性的共振增强作用。我们发现
染料 4 的
TPA 截面有近一个数量级的增强,这被解释为电荷从 LPP π-中心转移到阳离子二芳胺端基的作用。