Tuning Magnetic and Photophysical Properties of Luminomagnetic Metal-Organic Framework Composites in an Inverse Core-Satellite Structure

Luminomagnetic composites have been synthesized that allow for an individual tuning of luminescence intensity, chromaticity and magnetization by combination of superparamagnetic, citrate-stabilized iron oxide nanoparticles with the luminescent MOFs (3)(infinity)[Ln(2)(BDC)(3)(H2O)(4)] (Ln=Eu, Tb; BDC2-=terephthalate). The components are arranged to a concept of inverse structuring compared to previous luminomagnetic composites with MOF@magnetic particle (shell@core) composition so that the luminescent MOF now acts as core and is covered by magnetic nanoparticles forming the satellite shell. Thereby, the magnetic and photophysical properties are individually tuneable between high emission intensity (1.2 center dot 10(6) cps mg(-1)) plus low saturation magnetization (6 emu g(-1)) and the direct opposite (0.09 center dot 10(6) cps mg(-1); 42 emu g(-1)) by adjusting the particle coverage of the MOF. This is not achievable with a core-shell structure having a magnetic core and a dense MOF shell. The composition of the composites and the influence of different synthesis conditions on their properties were investigated by SEM/EDX, PXRD, magnetization measurements and photoluminescence spectroscopy.

Automated summary

Luminomagnetic composites consisting of superparamagnetic iron oxide nanoparticles and luminescent MOFs were synthesized, allowing for individual tuning of luminescence intensity, chromaticity, and magnetization. By reversing the structure compared to previous composites, the luminescent MOF acts as the core and is covered by magnetic nanoparticles forming the satellite shell. The magnetic and photophysical properties can be adjusted by changing the particle coverage of the MOF. The composition and synthesis conditions of the composites were analyzed using various techniques.