Dear Muhammad,
looks to me like you are dealing restricted molecular motion (e.g.
Pi-stacking) and/or a second species due to chemical exchange
(protonation and/or different stereoisomers due to the nitrogen centre
and its lone pair). The latter you can deal with by switching solvent
and controlling the pH, the former via dilution and elevated temperature
Chemical exchange:
In the first case KB-P19-NOâ‚‚ with the acidity of CDCl3, which might
give you at least partly a protonated species (the central Nitrogen in the
molecule should probably protonate pretty easily), which - depending on
what timescale this protonation is happening - will give you either just
a second set of signals or broad lines (as well).
The second molecule might have the same problem, with protonation of
either central nitrogen, the molecule will become non-symmetrical and
you will get broad lines depending on the exchange rate.
Best, André
--
Dr. André Dallmann
Leiter der NMR-Abteilung
Email: andre.dallmann_at_chemie.hu-berlin.de
Raum: 0'103
Telefon: 82952
Handy: 01797657855
ORCID-ID: https://orcid.org/0000-0002-0141-2635
Webseite: https://www.chemie.hu-berlin.de/en/forschung-en/nmr-spectroscopy/nmr-spectroscopy?set_language=en
Adresse:
Humboldt Universität zu Berlin
Institut für Chemie
AG NMR
Brook-Taylor-Str. 2
12489 Berlin
Deutschland
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Received on Wed Oct 01 2025 - 08:05:23 MST