[haichau]

Can you explain why the wavelength increase when 4-aminothiophenol group substitute chlorine atom in heptamethine cyanide dyes ?
Example : ADS830WS has wavelength 819nm.When ADS830WS react with 4-aminothiophenol in DMSO ( a little NaOH added to mixture), the product ADS832WS has its wavelength 822nm (increase)_.Explain?
Thanks

[sjb]

What happens in terms of the molecule when the amino group substitutes the chlorine, or when base acts on the thiophenol?

[haichau]

I have an experiment.The reactants are ADS830WS ( wavelength:819nm), NaOH, 4-aminothiophenol.After finish this experiment, I have product ADS832WS which have wavelength 824nm.The structure of ADS832WS have different which that of ADS830WS is chlorine atom at meso position have been replaced by 4-aminothiophenyl ( from 4-aminothiophenol).Help me this explain this ?

[sjb]

Ahh, I misunderstood - do you now have 4-aminophenyl phenyl sulfide?

What is the nature of the electronic transition you're observing?

[haichau]

You can read this attachment obviously