Effect of pH in the photoluminescence of a ruthenium complex featuring a derivative of the ligand pyrazine[2,3-f][1,10]-phenanthroline

• The synthesis and characterization of a new ruthenium complex is reported.
• The complex shows photoluminescence in both protic and aprotic solvents.
• Photoluminescence is quenched in water at low pH.

A new ruthenium complex, [Ru(bpy)2(dbe-ppl)](PF6)2 (bpy = 2,2′-bipyridine and dbe-ppl = dimethyl 4,4′-(pyrazino[2,3-f][1,10]phenanthroline-2,3-diyl)dibenzoate, has been synthesized and characterized by 1H NMR spectroscopy, UV–Vis, IR, and cyclic voltammetry.Irradiation on the MLCT band results in photoluminescence in both protic and aprotic solvents. The photoluminescence in water is pH dependent, it shows a behavior which can be described by the Henderson–Hasselbalch assuming the protonation/deprotonation of the excited state with a pKa of 2.40 ± 0.01.

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