The conformational analyses of 2-amino-N-[2-(dimethylphenoxy)ethyl]propan-1-ol derivatives in different environments

Four crystal structures of 2-amino-N-(dimethylphenoxyethyl)propan-1-ol derivatives, characterized by X-ray diffraction analysis, are reported. The free base (R,S)-2-amino-N-[2-(2,3-dimethylphenoxy)ethyl]propan-1-ol, C₁₃H₂₁NO₂, 1, crystallizes in the space group P2₁/n, with two independent molecules in the asymmetric unit. The hydrochloride, (S)-N-[2-(2,6-dimethylphenoxy)ethyl]-1-hydroxypropan-2-aminium chloride, C₁₃H₂₂NO₂⁺·Cl^-, 2c, crystallizes in the space group P2₁, with one cation and one chloride anion in the asymmetric unit. The asymmetric unit of two salts of 2-picolinic acid, namely, (R,S)-N-[2-(2,3-dimethylphenoxy)ethyl]-1-hydroxypropan-2-aminium pyridine-2-carboxylate, C₁₃H₂₂NO₂⁺·C₆H₄NO₂^-, 1p, and (R)-N-[2-(2,6-dimethylphenoxy)ethyl]-1-hydroxypropan-2-aminium pyridine-2-carboxylate, C₁₃H₂₂NO₂⁺·C₆H₄NO₂^-, 2p, consists of one cation and one 2-picolinate anion. Salt 1p crystallizes in the triclinic centrosymmetric space group P-1, while salt 2p crystallizes in the space group P4₁2₁2. The conformations of the amine fragments are contrasted and that of 2p is found to have an unusual antiperiplanar arrangement about the ether group. The crystal packing of 1 and 2c is dominated by hydrogen-bonded chains, while the structures of the 2-picolinate salts have hydrogen-bonded rings as the major features. In both salts with 2-picolinic acid, the specific R₁²(5) hydrogen-bonding motif is observed. Structural studies have been enriched by the generation of fingerprint plots derived from Hirshfeld surfaces.