Dear Lan Mei thank you for this very interesting technical question. There are a few studies available in the chemical literature in which the use tris(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) chloride to detect intracellular molecular oxygen is described. Please have a look e.g. at the following potentially useful links:

Oxygen Sensors Based on a Quenching of Tris-(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) in Fluorinated Polymers

Article Oxygen Sensors Based on a Quenching of Tris-(4,7-diphenyl-1,...

Ratiometric Dissolved Oxygen Sensors Based on Ruthenium Complex Doped with Silver Nanoparticles

Article Ratiometric Dissolved Oxygen Sensors Based on Ruthenium Comp...

A Water-Soluble Luminescence Oxygen Sensor

Article A Water-Soluble Luminescence Oxygen Sensor

Dear all, in addition to the valable references given by Prof. Frank T. Edelmann, it is worth noting the importance of two major factors for thiese kinds of complexes: the limit detection (by PET, FRET, or other techniques) and the life time. Also O2 metabolites and the other forms of reactive oxygen species (ROS) should also be considered for their possible interferences. Please check for additional details the attached files. My Regards

The commercially available O2 sensors use the quenching of photochemically generated exited state of Ru(II)(bpy)3 by O2 to measure the O2 concentrations. Hypothetically, tris(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) can be also used. What are you interested on? To use this complex to detect O2 or you want to detect O2 regardless of the chemistry behind the sensor?

Dear Lan Mei;

Please see the attached files.

With my best regards

Dear Lan Mei, please refer following techniques

Article Luminescence Oxygen Sensor Based on a Ruthenium(II) Star Pol...

Dear Lan,

Many thanks for this very interesting technical question as Prof. Edelmann and others already pointed out!

Indeed Ru2+ is, as Fe2+ is, a a very good metal center to coordinate O2 by pi-backbonding due to the high electron density on an [Ar]3d6 or [Kr]4d6 ion. However, I doubt that the star type complexes are ideal, since in [Ru(dpp)3]2+ and similar octadrehal complexes the ligand exchange is rather slow due the strong bonding of the chelating phenanthroline ligands and the rather large crystal-field stabilisation energy of such diamagnetic low-spin complexes.

During my Ph.D. work, which can be found on RG, a Ru-complex according to [Ru(tmtacn)(bqdi)(H2O)]2+ (tmtacn = 1,4,7-trimethyl-1,4,7-triazacyclononane and bqdi = benzoquinondiimine) was synthesised, wherein H2O can be easily exchanged by Cl-, N3-, OCN-, or other monodentate ligands. I never tried Oxygene unfortunately, but this would be my proposal for you. The complexes were reddish and showed red luminescent and certainly will show a change in the decay time upoon ligand exchange, since if the H2O ligand is replaced by O2 or other ligands with lower vibration frequencies, multiphonon quenching of the Ru2+ CT PL shall be reduced.

Good luck with your research,

Thomas

PS: The ligand was those days available by Unilever, NL!