Kundi Varun, Alam Md Mehboob, Thankachan Pompozhi Protasis
Theoretical Chemistry Lab, Department of Chemistry, Indian Institute of Technology, Roorkee, Roorkee-247667, India.
Phys Chem Chem Phys. 2015 Mar 14;17(10):6827-33. doi: 10.1039/c5cp00026b.
In the present work, we have studied the gas phase one- and two-photon absorption (OPA and TPA) properties of the first two excited states of the triply twisted Möbius annulene molecule (G. R. Schaller, et al., Nat. Chem. 2014, 6, 608) and five model systems substituted with different donor and acceptor groups. The main purpose of this study is to explore the OPA and TPA properties of this newly synthesized molecule and the unique π-conjugation provided by it. We have used the linear and quadratic response theory methods with the CAMB3LYP functional and the cc-pVDZ basis set for calculating the required parameters. Our results indicate that in the absence of any directive force (i.e. the donor-acceptor groups) the unsubstituted molecule is completely TP inactive. However, as soon as we insert the donor-acceptor group the system becomes TP active which can further be enhanced (up to 3640 GM in our case) by changing the donor-acceptor groups. We have explained the results by performing a two-state model calculation and by analyzing the TP tensor elements and the orbitals involved in the transition processes.
在本工作中，我们研究了三重扭曲莫比乌斯轮烯分子（G. R. 沙勒等人，《自然·化学》，2014年，第6卷，第608页）的前两个激发态以及五个被不同供体和受体基团取代的模型体系的气相单光子吸收（OPA）和双光子吸收（TPA）性质。本研究的主要目的是探索这种新合成分子的OPA和TPA性质以及它所提供的独特π共轭。我们使用了带有CAMB3LYP泛函和cc-pVDZ基组的线性和二次响应理论方法来计算所需参数。我们的结果表明，在没有任何导向力（即供体 - 受体基团）的情况下，未取代的分子完全没有双光子活性。然而，一旦我们插入供体 - 受体基团，体系就会变得具有双光子活性，通过改变供体 - 受体基团，这种活性还可以进一步增强（在我们的例子中高达3640 GM）。我们通过进行双态模型计算以及分析双光子张量元素和跃迁过程中涉及的轨道来解释这些结果。
