Structural studies on lithocholyl-N-(2-aminoethyl)amide in the solid state

Abstract

The synthetic procedure of lithocholyl-N-(2-aminoethyl)amide yielded a mixture of several forms detected by solid state 13C CP/MAS NMR although the solution state NMR unambiguously ascertained that the compound was pure. By recrystallization from various solvents one pure polymorph alongside with four solvates were isolated. The structures of the pure polymorph and the solvates were characterized by 13C and 15N CP/MAS NMR and powder X-ray diffraction (PXRD) methods. Variable contact time and dipolar dephasing experiments were employed to obtain optimized CP parameters and to distinguish various CHn (n = 0–3) resonances. CSA analyses of spinning side bands at different spinning rates showed small variations in the shielding tensor values of the carbonyl group between the pure polymorph (recrystallized from acetonitrile, tetrahydrofuran and 1,4-dioxane) and p-xylene solvate.