UV electronic excitations in acidic sugars

We report a theoretical work on the electronic excitation spectrum of two heparins like disaccharides. Time dependent density functional theory (TD-DFT) calculated spectra for these sulfated and carboxylated disaccharides are presented. The orbitals involved in the observed electronic excitations are analyzed. ππ∗ excitations involving the acidic functions lead to a strong optical absorption of these compounds between 270 and 220 nm, which is in agreement with experimental spectra reported previously [16].