Cyanine self-association

Cyanine borates exist as tight ion pairs certain of the salts have even been shown to form ion pairs in which the center-to-center distance between the ions is less than the sum of the individual radii [27-29]. Since the lifetime of the excited singlet state of cyanine dye is quite short, too short to allow an efficient encounter at an achievable concentration of borate in a situation in which diffusion is necessary, the self-association of the cyanine cation and borate anion is a prerequisite for efficient photoinduced reaction. 

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