Structures of the hydrate and dihydrate forms of the DNA-binding radioprotector methylproamine.

Methyl proamine {N,N,3-trimethyl-4-[6-(4-methylpiperazin-1-yl)-1H,3'H-[2,5'-bibenzo[d]imidazol]-2'-yl]aniline}, C28H35N7O2, crystallized as both a dihydrate, C28H31N7·2H2O, and monohydrate, C28H31N7·H2O, form from water in the presence of β-cyclodextrin, in the P21/c and P21/n space groups, respectively. The two structures adopt different conformations and tautomeric forms as a result of the differing crystal packing as dictated by hydrogen-bonding interactions. The dihydrate crystallizes as a three-dimensional hydrogen-bonded network, while the monohydrate crystallizes as a two-dimensional hydrogenbonded network. [ABSTRACT FROM AUTHOR]