近日，陕西师范大学刘太宏团队研究了吲哚二噻吩在推拉发色团中增强双光子吸收和有效非线性光学限制的多种作用。该研究于2025年8月27日发表在《结构化学》杂志上。

可调谐光学性质与推拉结构特性之间的相关性在材料科学和非线性光学领域引起了广泛关注。研究组对几种具有不同末端取代基的茚并二噻吩（IDT）衍生物（表示为IDT-2NA、NA-IDT-CN和IDT-2CN）进行了比较研究，以证明它们内在的结构-性质关系。有趣的是，IDT核心在获得的三种衍生物中扮演着受体（A）和供体（D）的不同角色。具有D-a-D结构的对称IDT-2NA在THF中显示出约459nm的最大吸收。与具有反向a-D-a特征的对称模拟IDT-2CN相反，具有不同D-D′-a基序的NA-IDT-CN具有明显的溶剂极性效应。 

理论计算和静电势结果证实，具有不同电子共轭的末端取代基在影响所得光物理性质方面起着至关重要的作用。利用飞秒开孔Z扫描技术，研究组在540至900 nm范围内获得了显著的双光子吸收（2PA）能力。中心对称IDT-2CN的2PA截面（δ_2PA）最大值约为5390GM，在600nm处显示。飞秒跃迁吸收的不同激发态动力学支持了有效的分子内电荷转移，这解释了δ_2PA值的提高。进一步评估了它们基于2PA机制的潜在光功率限制应用。该研究发现具有IDT-2CN序列的三个IDT衍生物的极限阈值为2.79-3.35 mJ/cm²。

附：英文原文

Title: Diverse roles of indacenodithiophene in push-pull chromophores for enhanced two-photon absorption and efficient nonlinear optical limiting

Author: anonymous

Issue&Volume: 2025-08-27

Abstract: Correlation between tunable optical properties and push-pull structural characters have attracted extensive attention in material science and nonlinear optics. Here, several indacenodithiophene (IDT) derivatives denoted as IDT-2NA, NA-IDT-CN, and IDT-2CN with different terminal substituents were investigated comparatively to demonstrate their intrinsic structure-property relationships. Interestingly, the IDT core act diverse roles as acceptor (A) and donor (D) in the obtained three derivatives. Symmetric IDT-2NA with a D-A-D architecture showed an absorption maximum around 459 nm in THF. Contrary to the symmetric analog IDT-2CN with a reverse A-D-A feature, NA-IDT-CN with a different D-D′-A motif characterized an obvious solvent polarity effect. Theoretical calculation and electrostatic potential results confirmed the terminal substituents with different electronic conjugation play vital roles in affecting the resultant photophysical properties. Utilizing the femtosecond open-aperture Z-scan technique, significant two-photon absorption (2PA) capabilities were obtained ranging from 540 to 900 nm. The 2PA cross section (δ2PA) maximum about 5390 GM of centrosymmetric IDT-2CN exhibited at 600 nm. Distinct excited-state dynamics with the help of femtosecond transition absorption supported the effective intramolecular charge transfer which account for enhancing δ2PA values. Their potential optical power limiting applications based on the 2PA mechanism were further evaluated. The limiting thresholds were found to be 2.79-3.35 mJ/cm2 for the three IDT derivatives with a sequence of IDT-2CN

DOI: 10.1016/j.cjsc.2025.100704

Source: http://cjsc.ac.cn/cms/issues/856