TY  - CONF
A1  - Resch-Genger, Ute
T1  - Assessing different types of silica networks for the complete protection of nir luminescent molecular rubies from oxygen quenching in air
N2  - The application of emerging luminophores such as near-infrared (NIR) emissive earth-abundant chromium(III) (CrIII) complexes and triplet-triplet annihilation upconversion (TTA-UC) systems in air as optical reporters for bioimaging or photonic materials for energy conversion requires simple and efficient strategies for their complete protection from luminescence quenching by oxygen. Therefore, we explored the influence of sol-gel synthesis routes on the oxygen protection efficiency of the resulting core and core/shell silica nanoparticles (SiO2 NPs), utilizing the molecular ruby-type luminophores CrPF6 ([Cr(ddpd)2](PF6)3; ddpd = N,N’-dimethyl- N,N’-dipyridin-2-ylpyridin-2,6-diamine) and CrBF4 ([Cr(ddpd)2](BF4)3) with their oxygen-dependent, but polarity-, proticity-, viscosity-, and concentration-independent luminescence as optical probes for oxygen permeability. The sol-gel chemistry routes we assessed include the classical Stöber method and the underexplored larginine approach, which relies on the controlled hydrolysis of tetraethoxysilane (TEOS) in a biphasic cyclohexane/water system with the catalyst l-arginine. As demonstrated by luminescence measurements of air- and argon-saturated dispersions of CrPF6- and CrBF4-stained SiO2 NPs of different size and particle architecture, utilizing the luminescence decay kinetics of argon-saturated solutions of CrPF6 and CrBF4 in acetonitrile (ACN) as benchmarks, only SiO2 NPs or shells synthesized by the l-arginine approach provided complete oxygen protection of the CrIII complexes under ambient conditions. We ascribe the different oxygen shielding efficiencies of the silica networks explored to differences in density and surface chemistry of the resulting nanomaterials and coatings, leading to different oxygen permeabilities. Our l-arginine based silica encapsulation strategy can open the door for the efficient usage of oxygen-sensitive luminophores and TTA-UC systems as optical reporters and spectral shifters in air in the future.
T2  - eMRS Strasbourg
CY  - Strasbourg, France
DA  - 26.05.2025
KW  - Quality assurance
KW  - Fluorescence
KW  - Nano
KW  - Particle
KW  - Synthesis
KW  - Quantum yield
KW  - NIR
KW  - Mechanism
KW  - Characterization
KW  - Electron microscopy
KW  - Silica
KW  - Oxygen sensing
KW  - Surface
KW  - Doping
KW  - Lifetime
KW  - Cr(III) complex
PY  - 2025
AN  - OPUS4-63300
LA  - eng
AD  - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER  -