XPost: sci.chem   
   From: a202010@lycos.com-   
      
   Timothy Sutter wrote:   
      
   > 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.   
      
      
      
   of course, auxochromes in the para position of a benzene/aromatic ring   
   system   
   would pull the chromophore in to the conjugated system through   
   resonance.   
      
   so, you'd have charge delocalization on a benzene/aromatic ring system   
   but, this would exclude the chromophore in the absence of an auxophore.   
      
      
      
   > 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?   
      
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