Integration shows that the perfectly folded conformation accounts for more than 95% of the population. This is substantially higher than for unsubstituted hepta(o-phenylene). The electron-withdrawing imide group is expected to improve folding by strengthening the aromatic stacking interactions that stabilize the folded state. In these heptamers the imide is particularly well-located as it interacts directly with the ends of the oligomer, where misfolding tends to occur. 1 H NMR spectra of the chiral phthalimide heptamers (S )-oP 7 ( t Bu), (R)-oP 7 ( i Pr), (R)-oP 7 (Ph), and (S )-oP 7 (Bo) are shown in Figure . Despite the increased bulk of the imides, the oligomers are still predominantly well-folded (see Table ), remaining roughly 95% well-folded on the basis of NMR integration. Signals from oP 7 (Me) are doubled in (R)-oP 7 ( i Pr), (R)-oP 7 (Ph), and (S )-oP 7 (Bo) reflecting the now-inequivalent left-and righthanded helices of the o-phenylene. This is particularly obvious in the singlets for proton H 4b .