Abstract: Atomic electronegativity interaction vector (AEIV) and atomic hybridation state index (AHSI) were employed for quantitative structure spectroscopy relationship modeling of ¹³C NMR chemical shifts of the carbon atoms in protoberberine alkaloids. The five-parameter model yielded r, q, RMSEE and RMSCV of 0.982 9, 0.982 1, 7.732 9 and 7.884 3, respectively. Leave-one-molecule-out (LMO) method and cross test (CT) were combined to test the reliability of this model, and the results appeared satisfactory. Predicted chemical shifts of the samples were in good linear relationship with the experimental data, with r_predof 0.982 9, 0.986 5 and 0.982 1 respectively. The model was also used to predict unknown ¹³C NMR chemical shifts of 58 carbon atoms in four protoberberine compounds, and the results obtained were in agreement with calculated results using the gNMR software.

Key words: atomic electronegativity interaction vector, atomic hybridation state index, NMR, chemical shift, protoberberine alkaloids