State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun, People's Republic of China.
J Mol Model. 2011 Jun;17(6):1413-25. doi: 10.1007/s00894-010-0839-9. Epub 2010 Sep 16.
Two important classes of organic molecules, perylene diimide (PDI) and pyrene derivatives have been found to possess relatively excellent photophysical and photochemical properties and especially high two-photon absorption cross sections (δ(T)(max)). Herein, one-photon absorption (OPA) and two-photon absorption (TPA) properties of some novel PDI and pyrene derivatives were comparatively investigated by the density functional theory (DFT) and Zerner's intermediate neglect of differential overlap (ZINDO) methods. The calculated results indicate that with respect to PDI derivatives, the maximum TPA cross-sections for pyrene compounds increase obviously, the maximum peaks of OPA and TPA spectra are blue-shifted, the ΔE(H-L) (energy gaps between the highest occupied orbital and the lowest unoccupied orbital) increase. The different π-conjugated bridges (fluorene and pyrene) and terminal groups have slight effect on the OPA properties. Nevertheless, the molecules bearing 1,6-disubstituted pyrene as the π-conjugated bridge display the largest δ(T)(max) in both series of compounds 3 and 4. Moreover, the δ(T)(max) values of molecules with benzothiazole-substituted terminal groups are larger than those of the molecules with diphenylamine, which is attributed to benzothiazole groups stabilizing the planarity of the branch parts, extending the conjugated length and increasing the π-electron delocalized extent. Furthermore, the molecular size has marked effect on OPA and TPA properties. It is worthy to mention that cruciform 8 displays the largest δ(T)(max) among all the studied molecules in the range of 600-1100 nm. This research could provide a better understanding for the origin of the linear and nonlinear optical properties, and it would be helpful to gain more information about designing two-photon absorption materials with large δ(T)(max).
两类重要的有机分子，即苝二酰亚胺（PDI）和芘衍生物，已被发现具有相对优异的光物理和光化学性质，特别是具有较高的双光子吸收截面（δ（T）（max））。在此，通过密度泛函理论（DFT）和 Zerner 的中间忽略微分重叠（ZINDO）方法比较研究了一些新型 PDI 和芘衍生物的单光子吸收（OPA）和双光子吸收（TPA）性质。计算结果表明，对于 PDI 衍生物，芘化合物的最大 TPA 截面明显增加，OPA 和 TPA 光谱的最大峰值蓝移，ΔE（H-L）（最高占据轨道和最低未占据轨道之间的能隙）增加。不同的π共轭桥（芴和芘）和末端基团对 OPA 性质有轻微影响。然而，具有 1,6-取代芘作为π共轭桥的分子在化合物 3 和 4 的两个系列中均显示出最大的δ（T）（max）。此外，带有苯并噻唑取代末端基团的分子的δ（T）（max）值大于带有二苯胺的分子，这归因于苯并噻唑基团稳定支链部分的平面性，扩展共轭长度并增加π-电子离域程度。此外，分子尺寸对 OPA 和 TPA 性质有显著影响。值得一提的是，十字形 8 在 600-1100nm 范围内所有研究分子中显示出最大的δ（T）（max）。这项研究可以更好地理解线性和非线性光学性质的起源，并有助于获得更多关于设计具有大δ（T）（max）的双光子吸收材料的信息。
