Excited states of 4-dimethylaminopyridines: magnetic circular dichroism and computational studies.
The ultraviolet transitions of 4-(dimethylamino)pyridine and its derivatives: 3-methyl-4-(dimethylamino)pyridine and 3,5-dimethyl-4-(dimethylamino)pyridine were investigated by electronic absorption and magnetic circular dichroism (MCD) spectroscopy, and by quantum chemical calculations. The ortho-methylation in the pyridine ring creates a steric hindrance to coplanarity. The resulting changes in the strength of the dimethylamino substitutent are reflected in the MCD spectra. Near-UV experimental data indicate a presence of three low-energy transitions, assigned to 1Lb, 1La and 1(n,pi*) excited states. These results are corroborated by TD-DFT and INDO/S calculations.
Szydłowska
Izabela
I
Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44152, 01-224 Warsaw, Poland.
Kyrychenko
Alexander
A
Gorski
Alexander
A
Waluk
Jacek
J
Herbich
Jerzy
J