Enhancing Dynamic Spectral Diffusion in Metal-Organic Frameworks through Defect Engineering.
Arjun HalderDavid C BainJulia OktawiecMatthew A AddicoatStavrini TsangariJosé J Fuentes-RiveraTristan A PittAndrew J MusserPhillip J MilnerPublished in: Journal of the American Chemical Society (2023)
The crystal packing of organic chromophores has a profound impact on their photophysical properties. Molecular crystal engineering is generally incapable of producing precisely spaced arrays of molecules for use in photovoltaics, light-emitting diodes, and sensors. A promising alternative strategy is the incorporation of chromophores into crystalline metal-organic frameworks (MOFs), leading to matrix coordination-induced emission (MCIE) upon confinement. However, it remains unclear how the precise arrangement of chromophores and defects dictates photophysical properties in these systems, limiting the rational design of well-defined photoluminescent materials. Herein, we report new, robust Zr-based MOFs constructed from the linker tetrakis(4-carboxyphenyl)ethylene (TCPE 4- ) that exhibit an unexpected structural transition in combination with a prominent shift from green to blue photoluminescence (PL) as a function of the amount of acid modulator (benzoic, formic, or acetic acid) used during synthesis. Time-resolved PL (TRPL) measurements provide full spectral information and reveal that the observed hypsochromic shift arises due to a higher concentration of linker substitution defects at higher modulator concentrations, leading to broader excitation transfer-induced spectral diffusion. Spectral diffusion of this type has not been reported in a MOF to date, and its observation provides structural information that is otherwise unobtainable using traditional crystallographic techniques. Our findings suggest that defects have a profound impact on the photophysical properties of MOFs and that their presence can be readily tuned to modify energy transfer processes within these materials.
Keyphrases
- metal organic framework
- energy transfer
- optical coherence tomography
- high glucose
- quantum dots
- diabetic rats
- dual energy
- drug induced
- endothelial cells
- health information
- wastewater treatment
- computed tomography
- magnetic resonance
- healthcare
- single cell
- single molecule
- pet imaging
- room temperature
- stress induced
- high density