Structural insights into methyl- or methoxy-substituted 1-(α-aminobenzyl)-2-naphthol structures: the role of C—H...π interactions

Abstract

Aminobenzylnaphthols are a class of compounds containing a large aromatic molecular surface which makes them suitable candidates to study the role of C—H...π interactions. We have investigated the effect of methyl or methoxy substituents on the assembling of aromatic units by preparing and determining the crystal structures of (S,S)-1-{(4-methylphenyl)[(1-phenylethyl)amino]methyl}naphthalen-2-ol, C26H25NO, and (S,S)-1-{(4-methoxyphenyl)[(1-phenylethyl)amino]methyl}naphthalen-2-ol, C26H25NO2. The methyl group influenced the overall crystal packing even if the H atoms of the methyl group did not participate directly either in hydrogen bonding or C—H...π interactions. The introduction of the methoxy moiety caused the formation of new hydrogen bonds, in which the O atom of the methoxy group was directly involved. Moreover, the methoxy group promoted the formation of an interesting C—H...π interaction which altered the orientation of an aromatic unit.