Photoswitching in Two-Component Surface-Mounted Metal–Organic Frameworks: Optically Triggered Release from a Molecular Container

Abstract

The remote control of surface properties is one of the key challenges in interfacial systems chemistry. Here, we report the realization of a SURMOF (surface-mounted metal-organic framework)-based hybrid system in which a crucial component can be switched by light. The realization of this two-component system is made possible by installing vertical compositional gradients via liquid-phase epitaxy. After loading the porous coating with guest molecules, its release is initiated by illumination with visible light and monitored by a quartz crystal microbalance.

Transparent films of metal-organic frameworks for optical applications

“…[24] In addition to this, hetero-layered SURMOFs with different composition and even different structures can be grown, [25][26] enabling various applications like the remote-controlled release from a porous container. [27] All these applications require thin films of very high quality with respect to thickness homogeneity, low roughness and low number of defects, which results also in a very high transparency of the MOF film. Therefore, the aim of this work is to further improve the SURMOF quality by increasing the homogeneity and decreasing the surface roughness.…”

The surface barrier phenomenon at the loading of metal-organic frameworks

“…Under adequate conditions, SURMOFs grow uniformly and film roughness as low as the size of a MOF unit cell can be achieved 23 . Apart from many potential applications, including chemical sensors and membranes, SURMOFs are well suited for a quantitative analysis of dynamic phenomena within MOFs [24][25][26] . In the present study we used HKUST-1, which is also known as Cu 3 ARTICLE commercially available 30 .…”

Application of metal and metal oxide nanoparticles@MOFs

“…Three strategies for triggered release of molecules have been explored using MOF composites: (1) Introduction of photo-switchable molecules into the pore networks that gives rise to guest release upon irradiation [192,193]; (2) Immobilization of target molecules into pore surfaces via photo-labile moieties that undergo controlled photolysis and release of the entrapped molecules [194,195]. We noted that both of these strategies require the specific chemical modifications to the pores' surface; and (3) Exploitation of metal/metal oxide nanoparticles@MOFs nanoparticles where external stimuli, such as a magnetic field or light, causes release of molecules by localized heating.…”