Polymethine

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An example of a polymethine

Polymethines are compounds of organic chemistry . They consist of an odd number of sp 2 hybridized chain links and an even number of electrons, i.e. H. there is an odd number of methine groups (CH groups) connected to one another by alternating single and double bonds.

Compounds that consist of an even number of methine groups are called polyenes .

properties

Cyanines are mostly used in photography, where they are used to sensitize photo emulsions.

In the case of polymethines, the ends of these chains consist of heteroatoms from groups 15 and 16 of the periodic table . This increases the mesomeric effect . Depending on the heteroatoms, the polymethines are divided into cyanines and merocyanines .

Ideal polymethines

In ideal polymethines, the end groups are symmetrical. One of the two end groups already carries a charge. An example of this would be ammonia and the ammonium ion .

See also

Individual evidence

  1. ↑ a b c Pharmacy. Retrieved June 5, 2019 .
  2. ↑ Structure and color of organic compounds in chemistry | School lexicon | Learning aid. Retrieved June 5, 2019 .