Synthesis, resolution and crystal structures of two enanti-omeric rhodamine derivatives

Clifton J Stephenson; Joel T Mague; Nathaniel Kamm; Nathalie Aleman; Dayla Rich; Quynh-Nhu Dang; Ha Van Nguyen

doi:10.1107/S2056989017001451

Synthesis, resolution and crystal structures of two enanti-omeric rhodamine derivatives

Acta Crystallogr E Crystallogr Commun. 2017 Feb 3;73(Pt 3):327-333. doi: 10.1107/S2056989017001451. eCollection 2017 Mar 1.

Authors

Clifton J Stephenson¹, Joel T Mague², Nathaniel Kamm¹, Nathalie Aleman¹, Dayla Rich¹, Quynh-Nhu Dang¹, Ha Van Nguyen¹

Affiliations

¹ Department of Chemistry, Loyola University, New Orleans, LA 70118, USA.
² Department of Chemistry, Tulane University, New Orleans, LA 70118, USA.

Abstract

The title mol-ecule, rac-6'-bromo-3'-di-ethyl-amino-3H-spiro-[2-benzo-furan-1,9'-xanthen]-3-one, C₂₄H₂₀BrNO₃, was synthesized and the two enanti-omers which formed were separated. The structures of all three compounds were determined and compared with those of a variety of related derivatives. A notable feature is the fold of the xanthene portion which ranges from 15.15 (13)° in the racemate to 2.42 (2)° in one mol-ecule of the R enanti-omer with that for the S enanti-omer having an inter-mediate value. The differences are attributed to the number and severity of inter-molecular inter-actions which include C-H⋯O hydrogen bonds, C-H⋯π(ring) and, in the S enanti-omer, a π-stacking inter-action between the carbonyl group and an aromatic ring.

Keywords: chiral sensors; crystal structure; hydrogen bond; rhodamine; xanthene.