ABSTRACT
Cycloparaphenylenes (CPP) can serve as both guest and host in a complex. Geometric analysis indicates that optimal binding occurs when the CPP nanohoops differ by five phenyl rings. Employing C-PCM(THF)/ωB97X-D/6-31G(d) computations, we find that the strongest binding does occur when the host and guest differ by five phenyl rings. The guest CPP is modestly inclined relative to the plane of the host CPP except when the host and guest differ by four phenyl rings, when the inclination angle becomes >40°. The distortion/interaction model shows that interaction dominates and is best when the host and guest differ by five phenyl rings. The computed (1)H NMR shifts of the guest CPP are shifted by about 1 ppm upfield relative to their position when unbound. This distinct chemical shift should aid in experimental detection of these CPP planetary orbit complexes.
