Heterocyclic betaines: pyridinium imidazolium azolate inner salts with

Heterocyclic Betaines Pyridinium (Imidazolium) Azolate Inner Salts with Several Interannular Linkages ... 

Pyridinium(imidazolium) inner azolate salts and molecules with a betaine character of general type 1 are attractive substrates from the viewpoint of structural chemistry, as mentioned in the Introduction. This ensemble of compounds offers the possibility of two terminal heterocyclic rings, joined through several spacers, with extreme characteristics within heteroaromatic systems a 7r-deficient nucleus (cation) and a 7r-excessive nucleus (anion). The high dipolar character is the distinctive feature offered by these compounds and has a powerful influence on their physical and chemical properties. 

---