Klokic Sumea, Naumenko Denys, Marmiroli Benedetta, Carraro Francesco, Linares-Moreau Mercedes, Zilio Simone Dal, Birarda Giovanni, Kargl Rupert, Falcaro Paolo, Amenitsch Heinz
Institute of Inorganic Chemistry, Graz University of Technology 8010 Graz Austria
Institute of Physical and Theoretical Chemistry, Graz University of Technology 8010 Graz Austria.
Chem Sci. 2022 Sep 27;13(40):11869-11877. doi: 10.1039/d2sc02405e. eCollection 2022 Oct 19.
Fundamental knowledge on the intrinsic timescale of structural transformations in photo-switchable metal-organic framework films is crucial to tune their switching performance and to facilitate their applicability as stimuli-responsive materials. In this work, for the first time, an integrated approach to study and quantify the temporal evolution of structural transformations is demonstrated on an epitaxially oriented DMOF-1-on-MOF film system comprising azobenzene in the DMOF-1 pores (DMOF-1/AB). We employed time-resolved Grazing Incidence Wide-Angle X-Ray Scattering measurements to track the structural response of the DMOF-1/AB film upon altering the length of the azobenzene molecule by photo-isomerization (-to-, 343 nm; -to-, 450 nm). Within seconds, the DMOF-1/AB response occurred fully reversible and over several switching cycles by cooperative photo-switching of the oriented DMOF-1/AB crystallites as confirmed further by infrared measurements. Our work thereby suggests a new avenue to elucidate the timescales and photo-switching characteristics in structurally responsive MOF film systems.
了解光开关金属有机骨架薄膜结构转变的固有时间尺度的基础知识对于调整其开关性能以及促进其作为刺激响应材料的应用至关重要。在这项工作中，首次在由DMOF-1孔中的偶氮苯组成的外延取向DMOF-1-on-MOF薄膜系统（DMOF-1/AB）上展示了一种研究和量化结构转变时间演变的综合方法。我们采用时间分辨掠入射广角X射线散射测量来跟踪DMOF-1/AB薄膜在通过光异构化改变偶氮苯分子长度时的结构响应（反式到顺式，343 nm；顺式到反式，450 nm）。几秒钟内，DMOF-1/AB响应完全可逆，并且通过取向的DMOF-1/AB微晶的协同光开关在几个开关周期内发生，红外测量进一步证实了这一点。我们的工作因此为阐明结构响应性MOF薄膜系统中的时间尺度和光开关特性提供了一条新途径。
