Fig. 9

Distribution of conformers according to the backbone type of Fig. 8. Dihedral angles \(\phi _1\), \(\phi _2\) and \(\phi _3\) correspond to the H-O-\(\hbox {C}_1\)-\(\hbox {C}_\alpha\), O-\(\hbox {C}_1\)-\(\hbox {C}_\alpha\)-N and \(\hbox {C}_1\)-\(\hbox {C}_\alpha\)-N-lp torsions, respectively (lp denotes the position of the N lone pair). Black, red, blue and green colors identify the I, II, III and IV types, respectively