Switch‐On Fluorescence of a Perylene‐Dye‐Functionalized Metal–Organic Framework through Postsynthetic Modification

Abstract

A perylene dye was introduced directly as a linker into a metal-organic framework (MOF) during synthesis. Depending on the dye concentration in the MOF synthesis mixture, different fluorescent materials were generated. The successful incorporation of the dye was proven by using (13) C and (27) Al MAS NMR spectroscopy, by solution NMR spectroscopy after digestion of the MOF sample, and by synthesizing a reference dye without connecting groups, which could coordinate on the metal-oxo cluster inside the MOF. Fluorescence quenching effects of the MOF linker, 2-aminoterephthalate, were observed and overcome by postsynthetic modification with acetic anhydride. We show here for the first time that amino groups, which can be used as anchoring points for covalent attachment of other molecules, are responsible for fluorescence quenching. Thus, a very promising strategy to implement switchable fluorescence into MOFs is shown here.

Pore wall fluorescence labeling of covalent organic frameworks

“…A great challenge in materials research is the synthesis of crystalline porous materials in which the molecular composition as well as physical and chemical properties can be systematically designed. In the past few years, this goal has been realized for a few select inorganic crystalline materials such as zeolites, 1,2 and for inorganic-organic hybrid metal organic frameworks (MOFs) [3][4][5][6] through a post-synthetic modification strategy, allowing for structural fine-tuning towards a desired functionality. Covalent organic frameworks (COFs) represent a new class of porous and crystalline materials formed by slightly reversible condensation reactions between molecular building blocks.…”

Investigation of the Co‐Dependence of Morphology and Fluorescence Lifetime in a Metal‐Organic Framework

“…The fluorescence of FITC, when covalently bound to the MOF, is quenched almost completely. It was postulated that the unreacted amino groups of the MOF play a key role in the quenching . To study how altering these interactions would affect the fluorophore, the FITC‐labeled MOFs were further modified postsynthesis with pivaloyl anhydride referred to as MIL‐101(Al)‐NH 2 ‐FITC/P (for details see the Supporting Information).…”

Nanoparticle Formation in Stable Microemulsions for Enhanced Oil Recovery Application

“…In case of MIL-88A and HKUST-1 ( Figure S18), however, no change in the characteristic correlation decay time could be detected. We attribute this to the known phenomenon of MOF induced fluorescence quenching 59,60 as well as rather large effective particle sizes, in particular of HKUST-1, resulting from aggregation, which both can cause a decline of detectable tags after binding. For Zrfum NPs several key observations could be made ( Figure 4).…”