Theoretical investigations of the hydrogen bond in a tetraamido/diamino quaternized macrocycle

ABSTRACT

We present theoretical investigations on the nature and persistence of the strong central hydrogen bond of a tetraamido/diamino quaternized macrocycle. Our theoretical study of the NMR properties of the central hydrogen bond proved difficult to reconcile with the available experimental results, suggesting the possibility of the non-persistence of the central hydrogen bond of the macrocycle in solution. We demonstrate alternative scenarios, in which a tautomerization of the macrocycle in solution gives rise to the experimentally observed NMR shifts.

GRAPHICAL ABSTRACT

KEYWORDS:

• NMR
• quantum chemistry
• hydrogen bond

Acknowledgements

We dedicate this work to the memory of Professor Dieter Cremer.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

We acknowledge financial support by the Deutsche Forschungsgemeinschaft (DFG) funding initiatives SFB749 (C7), and the Excellence Cluster EXC114 (CIPSM). C.O. further acknowledges financial support as Max-Planck-Fellow at MPI-FKF Stuttgart.