Water molecules in the crystal structure of tricyclic acyclovir

The biologically important molecule tricyclic acyclovir, presented here as 3-[(2-hydroxyethoxy)methyl]-6-methyl-3H-imidazolo[1,2-a]purin-9(5H)-one dih ydrate, C(11)H(13)N(5)O(3)(.-)2H(2) O, shows conformational flexibility, wh ich is observed in the solid state as two symmetrically independent molecul es with different side-chain conformations. Additionally, one of these mole cules exhibits side-chain disorder, such that there are three different con formations in the crystal. Water molecules found in the crystal form (H2O)( 8) clusters which are located between molecules of tricyclic acyclovir. The complex hydrogen-bond network formed between water and tricyclic acyclovir in the solid state may be related to the solvation of the molecules in sol ution.