1 H-Benzo[ g]pteridine-2,4-dione

Rao M Uppu; Frank R Fronczek

doi:10.1107/S2414314622012238

1 H-Benzo[ g]pteridine-2,4-dione

IUCrdata. 2023 Jan 6;8(Pt 1):x221223. doi: 10.1107/S2414314622012238. eCollection 2023 Jan.

Authors

Rao M Uppu¹, Frank R Fronczek²

Affiliations

¹ Department of Environmental Toxicology, Southern University and A&M College, Baton Rouge, LA 70813, USA.
² Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA.

Abstract

The structure of the title compound, C₁₀H₆N₄O₂, reported by Smalley et al. [(2021). Cryst. Growth Des. 22, 524-534] from powder diffraction data and ¹⁵N NMR spectroscopy, is confirmed using low-temperature data from a twinned crystal. The tautomer in the solid state is alloxazine (1H-benzo[g]pteridine-2,4-dione) rather than isoalloxazine (10H-benzo[g]pteridine-2,4-dione). In the extended structure, the mol-ecules form hydrogen-bonded chains propagating in the [01] direction through alternating centrosymmetric R ² ₂(8) rings with pairwise N-H⋯O inter-actions and centrosymmetric R ² ₂(8) rings with pairwise N-H⋯N inter-actions. The crystal chosen for data collection was found to be a non-merohedral twin (180° rotation about [001]) in a 0.446 (4):0.554 (6) domain ratio.

Keywords: Isoalloxazine; alloxazine; crystal structure; hydrogen bonding; tautomerism.

Grants and funding

The authors acknowledge the support from the National Institutes of Health (NIH) through the National Institute of General Medical Sciences (NIGMS) Institutional Development Award (IDeA) grant No. P20 GM103424–21 and the US Department of Education (US DoE; Title III, HBGI Part B grant No. P031B040030). Its contents are solely the responsibility of authors and do not represent the official views of NIH, NIGMS, or US DoE. The upgrade of the diffractometer was made possible by grant No. LEQSF(2011–12)-ENH-TR-01, administered by the Louisiana Board of Regents.