Predicting experimental complexation-induced changes in 1H NMR chemical shift for complexes between Zinc-porphyrins and Amines using the ab inito GIAO-HF methodology

Abstract

[eng] Ab initio calculations were carried out on zinc-porphyrins complexed to several amines: N-(3,5-dimethyl-pyridin-4-yl)-formamide, 1,4-diazabiciclo- [2.2.2]octane (DABCO), and 1-azabiciclo[2.2.2]octane (quinuclidine). The proton chemical shifts of these complexes were calculated ab initio at the GIAO-HF/6-311G*//HF/3-21G level of theory, and the obtained values agree satisfactorily with experimental results. The complexationinduced changes in 1H NMR chemical shifts correlate well with differences in association constants of several host-guest complexes.