Instant structure profiling of substituted catechins by chemical shift fingerprint of hydrogens of phenolic hydroxyl groups

- Integrated use of spectroscopic and computational methods for investigation.
- Established reliability of chemical shift of phenolic hydroxyl hydrogen.
- Structure profiling with hydroxyl hydrogen chemical shift fingerprint.

Proton NMR signals of the phenolic hydroxyl groups of the substituted catechins were successfully collected. The identities of these signals were elucidated and confirmed by a combination of computational and experimental investigations including GIAO-B3LYP NMR chemical shift calculation, kinetic analysis of acylation, and NOESY correlation. Furthermore, the reliability of chemical shifts of hydrogens of phenolic hydroxyl groups was confirmed by evaluation of the influence of acidic, basic and water residues. Finally, the chemical shift profiles of phenolic hydroxyl groups were developed for instant structural recognition. This study demonstrated the feasibility of application of chemical shifts of hydrogens of phenolic hydroxyl groups as fingerprint for structural determination and the concept could be extended to other polyphenols.