Synthesis and theoretical investigation of some new 4-substituted flavylium salts

Synthetic flavylium salts possess the same basic structure as anthocyanins and their color and physical-chemical properties are notably dependent on the nature and position of the functional groups attached to the skeleton. Influence of position C-4 is very dominant in the stabilization of these molecules and the presence of substituent at that position is highly desirable for a food colorant because it would be stable over a wide range of pH values. Flavylium salts substituted at 4-position with bulky hydroxyphenyl substituents were synthesized by acidic condensation according to a slightly modified procedure described by Robinson and Walker. Their thermodynamic properties and conformational analysis have been studied at DFT level.