Increasing the structural boundary of quasiracemate formation: 4-substituted naphthylamides

• Published in: CrystEngComm 2021-01, Vol.23 (1), p.21-215
• Main Authors: Craddock, Drew E, Parks, McKenzie J, Taylor, Lauren A, Wagner, Benjamin L, Ruf, Michael, Wheeler, Kraig A
• Format: Article
• Language: English
• Subjects: Cocrystallization; Crystallography; Enantiomers; Functional groups; NMR; Nuclear magnetic resonance; Single crystals; Thermal analysis
• ISSN: 1466-8033; 1466-8033
• DOI: 10.1039/d0ce01331e

Quasiracemates - materials consisting of pairs of near enantiomers - form crystalline motifs that mimic the inversion relationships observed for their racemic counterparts. Recent investigations from our group explored a family of chiral ( N -benzoyl)methylbenzylamines to understand the structural boundary of cocrystallization. This investigation extends these earlier studies to include naphthylamide quasiracemates, where the molecular framework is ∼20% larger by volume than the previous diarylamides. A family of naphthylamides was prepared where the pendant functional group differs incrementally in size ( i.e. , H to C 6 H 5 ) to give 55 possible unique pairs of racemic and quasiracemic combinations. Data collected from these materials using X-ray crystallography, thermal analysis methods and lattice energy calculations offer important insight into how a spatially larger naphthylamide molecular framework promotes greater structural variance of substituents during the pairwise assembly of quasienantiomers. Spatially larger naphthylamides than previously reported diarylamides promote greater structural variance of substituents during the pairwise assembly of quasienantiomers.