The hydrogen bond strength, geometry optimization and 1H NMR for naphthazarin (NZ) and its chlorine
substitutions have been calculated at the B3LYP/6-31G theoretical level.
The calculated chemical shifts of the chelated proton for all molecules, using GIAO method, are well
correlate with the calculated geometrical parameters results.
According to the calculated results, substitutions near the hydroxyl groups and near the carbonyl
groups increases and decreases the strength of the hydrogen bond, respectively.
By natural bond orbital (NBO) method, the effect of substitution on the hydrogen bond strength, the
charge distributions, steric effects, and electron delocalization in the studied compounds were investi-
gated. The natural bond orbital analysis very well explains the calculated results of substitution of chlo-
rine atoms on the hydrogen bond strength.
کلید واژگان :
Naphthazarin NBO Intramolecular hydrogen bond Ab initio calculation
