Structures of the hydrate and dihydrate forms of the DNA-binding radioprotector methyl-pro-amine.

Methyl pro-amine {N,N,3-trimethyl-4-[6-(4-methyl-piperazin-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 ß-cyclo-dextrin, 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 inter-actions. The dihydrate crystallizes as a three-dimensional hydrogen-bonded network, while the monohydrate crystallizes as a two-dimensional hydrogen-bonded network.