Assignment of pH-dependent NMR spectra of the scorpiand macrocycle: an application of titration profiles and spectral linewidths

✍ Scribed by Ryszard B. Nazarski

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 120 KB
• Volume: 41
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1111

✦ Synopsis

Abstract

Routine homo‐ and heteronuclear 2D NMR experiments (COSY, HMQC, TOCSY and ROESY) were performed for the complex macrocyclic pentaamine ligand 1‐(2′‐aminoethyl)‐1,4,8,11‐tetraazacyclotetradecane (1, scorpiand), derived from 1,4,8,11‐tetraazacyclotetradecane (cyclam). However, some its ^13^C and ^1^H resonances were distinguished only based on the similarity between profiles of relevant pH–chemical shift plots and/or linewidth considerations. Following this empirical method relying on the assumption that titration curves of nuclei in comparable chemical environments have comparable shapes, it was possible to assign all chemical shifts (^13^C, pH 0.25–13.4; ^1^H, pH 10–11.5) for some different protonated species H~n~1^n+^. A multiple experimental approach used for recognizing their NMR signals is offered as a general assignment procedure in the case of polyazamacrocycles. Copyright © 2002 John Wiley & Sons, Ltd.