We have investigated the electronic properties of carminic acid and glycosylated oxazines, phenoxazines, oxazones, and phenoxazones using AM1 semiempirical calculations to predict and understand the spectroscopic behavior of these molecules. These calculations have been used to predict electronic state odering, state dependent changes in charge distributions, and isomerization barriers for the molecules we report here. Comparison of fully protonated (neutral) carminic acid (H(3)CA) with the monodeprotonated form (H(2)CA(-)) shows that transition energies and state ordering change with the extent of protonation, but isomerization barriers for both forms are similar. We have also studied glycosylated oxazines and oxazones. The state ordering of the native and glycosylated oxazines and oxazones shows that glycoside modification does not affect the state ordering, and the rotational isomerization barriers for the glycosylated species show two minima separated by significant energy barriers. For the oxazines, there is a significant increase in S-0 reversible arrow S-1 transition energy associated with glycosylation, indicating the importance of steric effects associated with the chromophore modification. These calculations predict the formation of a twisted internal charge transfer (TICT) S-1 state in glycosylated oxazines arising from steric effects. These calculated data will be used as a tool for understanding the static and dynamic spectroscopic properties of these molecules as they are used to probe the nucleation and crystallization behavior of sugar solutions.