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

Emission quenching of [Ru(bpy) 2 (4,4′‐dcbpy) ] (PF 6 ) 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 ( K q ) are 5.5×10 9 (mol / L) −1 s −1 for 2 and 4.0×10 9 (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 ( k app ) was calculated to be 3×10 9 (mol/L) −1 for the interaction of excited 2 with 1, and 1.2×10 9 (mol/L) −1 for that of excited 3 with 1.