噻吩基卟啉衍生物的单光子和双光子吸收性质的理论研究

本文理论上研究了两个系列的噻吩基卟啉衍生物，这种衍生物在可见光区具有大的双光子吸收截面。用密度泛函理论和ZINDO-SOS方法，计算了分子的几何构型、电子结构，单光子和双光子吸收性质。结果显示噻吩单元的数目影响分子的单光子和双光子吸收性质。具有两个或三个噻吩基团的噻吩基卟啉衍生物在较大范围内具有可用于实际应用中的双光子吸收响应，这一性质有利于这类分子在光限幅中的应用。插入乙炔基有利于扩大共轭范围，增加分子的双光子吸收截面。同时，乙炔基团的加入导致了单光子和双光子波长的红移。从高透明性和相对大的非线性光学响应考虑，噻吩基卟啉衍生物是一类有应用前景的双光子吸收材料。

Theoretical Investigation on the One‐ and Two‐photon Absorption Properties of Porphyrin‐thiophene Chromophores

Two series of porphyrin‐thiophene chromophores were theoretically studied that exhibit large two‐photon absorption cross‐section in the visible region. The density functional theory (DFT) associated with ZINDO/SDCI methods has been used to calculate the molecular geometries, electronic structures, one‐photon and two‐photon absorption properties. The results show that the number of thiophene units affects the properties of one‐photon absorption (OPA) and two‐photon absorption (TPA). Porphyrin‐thiophene chromophores featuring two or three thiophene units have wide TPA response ranges; they can be applied to many nonlinear optical areas, such as optical limiting. Intervening ethynyl unit is beneficial to extend the conjugated pathway, and increase the two‐photon absorption cross‐section. At the same time, the OPA and TPA wavelengths are bathochromically shifted. From viewpoint of the high transparency and large nonlinear optical response, porphyrin‐thiophene chromophores will be promising TPA materials.