Photoinduced electron transfer of [ Ru (bpy)2 (4,4′‐dcbpy) ]2+ with electron donors

AbstractEmission quenching of [Ru(bpy)2(4,4′‐dcbpy) ] (PF6)2 (1) by benzenamine,4‐[2‐[5‐[4‐[4‐dimethylamino]phenyl]‐4,5‐dihydro‐l‐phenyl‐1H‐pyrazol‐3‐yl]‐ethenyl]‐N, N‐dimethyl (2) or 1,5‐diphenyl‐3–(2‐phenothiazine)‐2‐pyrazoline (3) was observed. Measurements of the emission decay of 1 before and after addition of 2 or 3 by single photon counting technique confirmed the observations. The emission quenching of 1 by 2 or 3 was submitted to Stern‐Volmer equation. It was calculated that the quenching rate constants (Kq) are 5.5×109 (mol/L)−1s−1 for 2 and 4.0×109 (mol/L)−1 for 3, respectively. These results indicated a character of dynamic quenching process. The singlet‐state of 2 or 3 was also quenched by 1. The quenching behaviors did not conform to the Stern‐Volmer equation and involved both static and dynamic quenching processes. The apparent quenching rate constant (kapp) was calculated to be 3×109 (mol/L)−1 for the interaction of excited 2 with 1, and 1.2×109 (mol/L)−1 for that of excited 3 with 1.