Spirooxazine-Fulgide Biphotochromic Molecular Switches with Nonlinear Optical Responses across Four States

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• 作者：Jianyong Yuan ; Yizhong Yuan ; Xiaohui Tian ; Jinyu Sun ; Ya Ge
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：July 14, 2016
• 年：2016
• 卷：120
• 期：27
• 页码：14840-14853
• 全文大小：842K
• 年卷期：0
• ISSN：1932-7455

文摘

A new type of prototypical biphotochromic switches combining spirooxazine and fulgide has been synthesized, and their nonlinear optical (NLO) responses have been theoretically studied on the basis of density functional theory (DFT). Our DFT calculations show that the introduction of a fulgide fragment (E and C) into the spirooxazine host can largely enhance the static second- and third-order NLO responses. Moreover, the photoisomerization of spirooxazine derivatives (SO-E and SO-C) brings forth a pronounced change in the geometry accompanied by the formation of a larger π-conjugated system, and thus the corresponding merocyanine derivatives (PMC-E and PMC-C) obtain ∼3.5-times enhancement of static second- and third-order NLO responses. Nevertheless, the difference in NLO responses between the E-form series (SO-E and PMC-E) and the C-form series (SO-C and PMC-C), respectively, is not substantial, which means the fulgide fragment in the prototypical biphotochromic system does not considerably differentiate the corresponding optical nonlinearities. To separate well the NLO responses of four states in our prototype, we further propose a structural modification strategy by introducing the furan moiety (2-vinylfuran) into the π-bridge, and the corresponding NLO performances from DFT results finally meet our demands, indicating that such a revised biphotochromic system based on our prototype is a fascinating choice for the architecture of multistate NLO switches.