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Photochemical Modulation of RuK Catalyzed Belousov-Zhabotinsky Reaction

T. Matsumura-Inoue, Y. Nakamichi, and T. Yamaguchi
[ACH-Models in Chemistry, Vol. 135, No. 3, pp. 305-313, 1998]

The Belousov-Zhabotinsky (BZ) reaction with photosensitive RuII catalyst changes its reaction phase from oscillatory region to steady state more easily under illuminated conditions, resulting in the modulation or the cessation of oscillation. Photochemical modulation of BZ reaction in a batch system was found to be classified into two modes, A and B. By illumination, the oscillation period was shortened in mode A ([malonic acid]/[bromate]>1), while the period was elongated in mode B. Other oscillatory parameters such as amplitude and potential range were also studied under illuminated and/or non-illuminated conditions.


Table 1 Effect of Illumination on mRu(bpy)32+ and [Br-] Oscillation of Type A and B
                                                                                  
                           Oscillation mode
                             Type A                          Type B
  Parameter        IlluminatedNon-illuminated      Illuminated    Non-illuminated
                                                                                  
EPtmV vs.SCE      1.313-1.033    1.258-1.033       1.315-1.033    1.303-1.033

[Ru(bpy)2+3],10-5M     4-20          12-20              7-40           8-40
,[Ru(bpy)32+],10-5M   16             8                 33             32
[Br-],10-5M          2.6-0.1        1.4-0.1           4.0-0.1       19.0-0.3
[Br-],10-5M          2.5            1.3               3.9           18.7
[Br-]/[Ru(bpy)32+  0.16          0.16               0.12           0.58
Initial condition: Type A: 0.2 mM 0, 16.0 mM [Ru(bpy)32+]0,16.0 mM[MA]0, 10.5 mM[BrO3-]0, Type B: 0.4 mM [Ru(bpy)32+]0, 16.0 mM [MA]0, 21.0 mM [BrO3-]0,in 0.8 M [H2SO4],I0 = 9.46 mW/cm2.

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