The application of emerging luminophores such as near-infrared(NIR)emissive complexes based on earth-abundant chromium as central ion and triplet-triplet annihilation upconversion(TTA-UC)systems in air as optical repo...The application of emerging luminophores such as near-infrared(NIR)emissive complexes based on earth-abundant chromium as central ion 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(SiO_(2)NPs),utilizing the molecular ruby-type luminophores CrPF_(6)([Cr(ddpd)_(2)](PF_(6))_(3);ddpd=N,N′-dimethyl-N,N′-dipyridin-2-ylpyridin-2,6-diamine)and CrBF_(4)([Cr(ddpd)_(2)](BF_(4))_(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 L-arginine 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 CrPF_(6)-and CrBF_(4)-stained SiO_(2)NPs of different size and particle architecture,utilizing the luminescence decay kinetics of argon-saturated solutions of CrPF_(6)and CrBF_(4)in acetonitrile(ACN)as benchmarks,only SiO_(2)NPs or shells synthesized by the L-arginine approach provided complete oxygen protection of the CrⅢcomplexes 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.展开更多
基金supported by the Scientific Service Units of IST Austria through resources provided by the Electron Microscopy FacilityThe authors gratefully acknowledge financial support by the projects AquaFunkNano(Federal Ministry for Economic Affairs and Climate Action(BmWK,program WIPANO))+1 种基金MiGraGen(Novo Nordisk Fonden,Interdisciplinary Synergy Program 2021),grant No.P-34662 from the Austrian Science Foundation(M.R.R.)the DFG project NILECHROME 2.0(grants RE 1203/23-2 and HE 2778/10-2).
文摘The application of emerging luminophores such as near-infrared(NIR)emissive complexes based on earth-abundant chromium as central ion 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(SiO_(2)NPs),utilizing the molecular ruby-type luminophores CrPF_(6)([Cr(ddpd)_(2)](PF_(6))_(3);ddpd=N,N′-dimethyl-N,N′-dipyridin-2-ylpyridin-2,6-diamine)and CrBF_(4)([Cr(ddpd)_(2)](BF_(4))_(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 L-arginine 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 CrPF_(6)-and CrBF_(4)-stained SiO_(2)NPs of different size and particle architecture,utilizing the luminescence decay kinetics of argon-saturated solutions of CrPF_(6)and CrBF_(4)in acetonitrile(ACN)as benchmarks,only SiO_(2)NPs or shells synthesized by the L-arginine approach provided complete oxygen protection of the CrⅢcomplexes 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.
