XPost: sci.chem   
   From: a202010@lycos.com-   
      
   Salmon Egg wrote:   
      
   >  Timothy Sutter wrote:   
      
   > > Salmon Egg wrote:   
      
   <...>   
      
   > > > Can a dopant be considered to be an auxochrome?   
      
   > > if you were to say that a 'sensitizer' heightens   
   > > the luminosity of the 'activator,' then you could   
   > > say it was 'like' an auxochrome which may heighten   
   > > the intensity of the chromophore's color,   
      
   > > is it -possible- to make a useful analogy?   
      
   > > maybe sort of...   
      
   > > > Has anyone developed a meaningful model of a dye as the   
   > > > quantum version of a small classical antenna?   
      
   > > lots of them are conjugated double bond sytems   
   > > but the distance between single and double bonds   
   > > probably doesn't change much so it would be the   
   > > length of the conjugated system that may be   
   > > variable like an antenna which can be opened   
   > > and closed like rabbit ears.   
      
   > > meaning, i'd wonder if a single dye molecule could   
   > > be varied likrabbit ears, but a series of differently   
   > > sized dye molecules could be varied like rabbit ears,   
   > > but this would be difficult.   
      
      
   > I am thinking in terms of dopants allowing conductivity to occur in   
   > substantially insulating crystals. Diamond, with its large band-gap   
   > would be an insulator without dopant. Similarly, the auxochrome allows   
   > electron mobility on a conjugated chain.   
      
   i really don't think the auxochrome -allows- the mobility   
   in the sense that the mobility isn't there in the absence   
   of the auxochrome.   
      
   in a conjugated pi system, you're going to get   
   electron delocalization whether or not you have 'color'   
      
   it still seems that the auxochrome sort of contributes   
   to lowering the energy of the lowest unoccupied molecular   
   orbital or raising the energy of the highest unoccupied   
   orbital in the chromophore and/or the entire pi system.   
      
   that's how it's going to be like an antenna.   
      
   sort of like you're 'doping' in pieces of variant energies   
   into an existing pi system.   
      
   like, you have a long conjugated ethylene chain or   
   conjugated cyclic structure, and it behaves in a certain manner   
      
   and then you start hanging functional groups   
   on -that- structure, and the color varies.   
      
   no?   
      
   > I am trying to understand both by trying to understand similarities and   
   > differences. Apparently, you do not need a solvent to get color.   
   > Phthalocyanines absorb so strongly that they reflect complementary color.   
      
      
   i wouldn't doubt that most dye molecules are colored in the powdered   
   form.   
      
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