Sol-gel-Derived highly sensitive optical oxygen sensing materials using Ru(II) complex via covalent grafting strategy

Area of Science:

• Materials Science
• Chemical Engineering
• Analytical Chemistry

Background:

• Development of advanced materials for chemical sensing is crucial.
• Ruthenium(II) complexes are known for their luminescent properties, suitable for sensing applications.
• Sol-gel techniques offer versatile routes for creating hybrid materials.

Purpose of the Study:

• To prepare and characterize silica-based hybrid materials with covalently-grafted and physically-incorporated Ruthenium(II) complexes.
• To investigate and compare the oxygen sensing properties of these hybrid materials.
• To understand the influence of grafting method on oxygen sensitivity and material stability.

Main Methods:

• Sol-gel technique utilizing tetraethoxysilane and a functionalized Ruthenium(II) complex.
• Covalent grafting via condensation reaction involving triethoxysilyl groups.
• Physical incorporation of the Ruthenium(II) complex within the silica matrix.
• Luminescence quenching measurements to assess oxygen sensitivity.

Main Results:

• Successful preparation of silica-based hybrid materials with both covalent and physical incorporation of Ruthenium(II) complexes.
• Efficient luminescence quenching by oxygen observed in the silica matrix.
• Covalently-grafted samples demonstrated higher oxygen quenching sensitivity than physically-incorporated ones.
• The strong Si-CH2 bond in grafted samples enhanced excited state lifetimes and photobleaching resistance.
• Oxygen sensing data fitted well with Demas two-site and Lehrer models, indicating heterogeneous distribution.

Conclusions:

• Covalently grafting Ruthenium(II) complexes onto silica via sol-gel methods yields superior oxygen sensing materials.
• The enhanced performance is attributed to improved stability and photophysical properties conferred by covalent linkage.
• These hybrid materials show promise for advanced oxygen sensing applications.