Danilo González, Ojars Neilands and Marcos Caroli Rezende
The solvatochromic shifts of the two isomeric title betaines 4 and 5, built up from the unsubstituted pyridinio acceptor and phenoxide donor fragments, were recorded in twelve solvents and the data compared with results from semi-empirical (AM1) and ab initio (HF/6-311G and B3LYP/6-311G) calculations.