Metal–Organic Framework Photonic Balls: Single Object Analysis for Local Thermal Probing

Abstract

Due to their high porosity and chemical versatility, metal–organic frameworks (MOFs) exhibit physical properties appealing for photonic‐based applications. While several MOF photonic structures have been reported, examples of applications thereof are mainly limited to chemical sensing. Herein, the range of application of photonic MOFs is extended to local thermal and photothermal sensing by integrating them into a new architecture: MOF photonic balls. Micrometric‐sized photonic balls are made of monodispersed MOFs colloids that are self‐assembled via spray‐drying, a low‐cost, green, and high‐throughput method. The versatility of the process allows tuning the morphology and the composition of photonic balls made of several MOFs and composites with tailored optical properties. X‐ray nanotomography and environmental hyperspectral microscopy enable analysis of single objects and their evolution in controlled atmosphere and temperature. Notably, in presence of vapors, the MOF photonic balls act as local, label‐free temperature probes. Importantly, compared to other thermal probes, the temperature detection range of these materials can be adjusted “on‐demand.” As proof of concept, the photonic balls are used to determine local temperature profiles around a concentrated laser beam. More broadly, this work is expected to stimulate new research on the physical properties of photonic MOFs providing new possibilities for device fabrication.

Periodic Nanoporous Inorganic Patterns Directly Made by Self‐Ordering of Cracks

“…As a comparison, this value is two and three orders of magnitude higher than the temperature‐induced refractive index variation of poly(methyl methacrylate), and dense TiO 2 respectively [ 50 ] over a similar temperature range. [ 51 ] The thermal sensitivity of the porous crack‐patterned gratings is of the same order of magnitude of ZIF‐8 photonic balls in presence of EtOH vapors. [ 50 ] Notably, as shown in Figure 6d, the n / T curves at lower IPA P / P 0 (75%, 50%, and 25%) present the same sensitivity but are displaced toward lower temperatures.…”

Metal–organic framework-based photonic crystal platforms for gas sensing: a review

“…8d, M. Faustini et al 113 demonstrated the fabrication of MOF photonic spheres with amorphous photonic structures via a spray-drying approach, which was inexpensive with high throughput. This method for the preparation of MOF photonic balls shows versatility, which has great promise in the application of chemical sensing.…”

Recent advances in nanoarchitectures of monocrystalline coordination polymers through confined assembly

“…Spray dry could confine the colloidal particles in droplets. During evaporation, the particles could be squeezed through the shrinkage of the droplet size ( Figure 7a ) [ 138 ]. The polyhedra were assembled into balls, which could be used for measuring the temperature.…”

“… a) Schematic illustration of the self-assembly of ZIF-8 particles via spray drying. Figure 7a was reproduced from [ 138 ], C. Avci et al, “Metal-Organic Framework Photonic Balls: Single Object Analysis for Local Thermal Probing”, Advanced Materials, with permission from John Wiley and Sons. Copyright © 2021 WILEY‐VCH GmbH.…”