Chemical diversity in a metal–organic framework revealed by fluorescence lifetime imaging

Abstract

The presence and variation of chemical functionality and defects in crystalline materials, such as metal–organic frameworks (MOFs), have tremendous impact on their properties. Finding a means of identifying and characterizing this chemical diversity is an important ongoing challenge. This task is complicated by the characteristic problem of bulk measurements only giving a statistical average over an entire sample, leaving uncharacterized any diversity that might exist between crystallites or even within individual crystals. Here, we show that by using fluorescence imaging and lifetime analysis, both the spatial arrangement of functionalities and the level of defects within a multivariable MOF crystal can be determined for the bulk as well as for the individual constituent crystals. We apply these methods to UiO-67 to study the incorporation of functional groups and their consequences on the structural features. We believe that the potential of the techniques presented here in uncovering chemical diversity in what is generally assumed to be homogeneous systems can provide a new level of understanding of materials properties.

Large‐Scale, Bottom‐Up Synthesis of Binary Metal–Organic Framework Nanosheets for Efficient Water Oxidation

“…Metal‐organic frameworks (MOFs) have emerged as an exciting class of porous materials created by stitching together metal ions/clusters with organic linkers . Benefitting from diverse architectures and abundant active sites, MOFs have attracted considerable interest in many fields of research, such as gas storage and separation, sensing, luminescence, catalysis, and energy conversion . Promising strategies have been applied to the design of multifunctional MOFs, including for the modulation of crystal structures and the control of size/morphology, but their performances still require significant improvements.…”

Imaging defects and their evolution in a metal–organic framework at sub-unit-cell resolution

“…A combination of X-ray diffraction, electron diffraction and anomalous X-ray scattering identified the ordering of missing-cluster defects into nanoregions in a UiO-66(Hf) sample 25 . Fluorescence lifetime imaging revealed the spatial distribution of defects within individual UiO-67 (an isoreticular MOF of UiO-66) crystals at submicrometre resolution 26 . It is also known that the concentration of defects in UiO-66 can be tuned by adding various terminal monocarboxylic acids in the synthetic system as modulators 19 .…”

Large‐Scale, Bottom‐Up Synthesis of Binary Metal–Organic Framework Nanosheets for Efficient Water Oxidation

“…[1,2] Benefitting from diverse architectures and abundant active sites,M OFs have attracted considerable interest in many fields of research, such as gas storage and separation, [3,4] sensing, [5] luminescence, [6] catalysis, [7] and energy conversion. [1,2] Benefitting from diverse architectures and abundant active sites,M OFs have attracted considerable interest in many fields of research, such as gas storage and separation, [3,4] sensing, [5] luminescence, [6] catalysis, [7] and energy conversion.…”