Inside/Outside: Post-Synthetic Modification of the Zr-Benzophenonedicarboxylate Metal-Organic Framework.

The Zr-based metal-organic framework, Zr-bzpdc-MOF, contains the photoreactive linker molecule benzophenone-4,4'-dicarboxylate (bzpdc) which imparts the possibility for photochemical post-synthetic modification. Upon irradiation with UV light, the keto group of the benzophenone moiety will react with nearly every C-H bond-containing molecule. Within this paper, we further explore the photochemical reactivity of the Zr-bzpdc-MOF, especially with regard to which restrictions govern internal versus external reactions. We show that apart from reactions with C-H bond-containing molecules, the MOF reacts also with water. By studying the reactivity versus linear alcohols we find a clear delineation in that shorter alcohol molecules (up to butanol as a borderline case) react with photoexcited keto groups throughout the whole crystals whereas longer ones react only with surface-standing keto groups. In addition, we show that with the alkanes n-butane to n-octane, the reaction is restricted to the outer surface. We hypothesize that the reactivity of the Zr-bzpdc-MOF versus different reagents depends on the accessibility of the pore system which in turn depends mainly on the size of the reagents and on their polarity. The possibility to direct the post-synthetic modification of the Zr-bzpdc-MOF (selective modification of the whole pore system versus surface modification) gives additional degrees of freedom in the design of this metal-organic framework for shaping and for applications.

Direct grafting-from of PEDOT from a photoreactive Zr-based MOF - a novel route to electrically conductive composite materials.

The postsynthetic potential of the two-dimensional metal-organic framework Zr-bzpdc-MOF which is based on the photoreactive molecule benzophenone-4,4'-dicarboxylic acid (H2bzpdc) is used here to selectively functionalize the MOF surface. We report the direct radical-induced oxidative grafting-from polymerization of the precursor EDOT on Zr-bzpdc-MOF, leading to an electrically conductive composite material and opening the road to a variety of applications.

Delamination and Photochemical Modification of a Novel Two-Dimensional Zr-Based Metal-Organic Frameworks.

In this contribution we present a novel two-dimensional Zr-based metal-organic framework (MOF) which offers the possibility for delamination and post-synthetic photochemical modification at the linker molecule derived from benzophenone-4,4'-dicarboxylic acid (H2 bzpdc). The new Zr-bzpdc-MOF crystallizes in the orthorhombic system as crystals with rhombic shape. The structure was determined from single-crystal diffraction data. The MOF is stable up to 300 °C in air and exhibits a moderate BET surface area of 650 m2 g-1 . The material can be obtained as thin sheets of a few nanometer thickness. Single crystals were modified post-synthetically, exploiting the intrinsic reactivity of the benzophenone group with C-H bond containing molecules. In this way, the surface properties of the MOF crystals (e.g., dispersibility in different solvents) can be changed drastically. Delamination and adaptation of the surface chemistry open up novel ways for shaping MOFs, for example, for the incorporation into polymer composites, and pave the way for various applications.

Validating Metal-Organic Framework Nanoparticles for Their Nanosafety in Diverse Biomedical Applications.

Metal-organic frameworks (MOFs) are promising platforms for the synthesis of nanoparticles for diverse medical applications. Their fundamental design principles allow for significant control of the framework architecture and pore chemistry, enabling directed functionalization for nanomedical applications. However, before applying novel nanomaterials to patients, it is imperative to understand their potential health risks. In this study, the nanosafety of different MOF nanoparticles is analyzed comprehensively for diverse medical applications. The authors first evaluate the effects of MOFs on human endothelial and mouse lung cells, which constitute a first line of defense upon systemic blood-mediated and local lung-specific applications of nanoparticles. Second, we validated these MOFs for multifunctional surface coatings of dental implants using human gingiva fibroblasts. Moreover, biocompatibility of MOFs is assessed for surface coating of nerve guidance tubes using human Schwann cells and rat dorsal root ganglion cultures. The main finding of this study is that the nanosafety and principal suitability of our MOF nanoparticles as novel agents for drug delivery and implant coatings strongly varies with the effector cell type. We conclude that it is therefore necessary to carefully evaluate the nanosafety of MOF nanomaterials with respect to their particular medical application and their interacting primary cell types, respectively.