Key points are not available for this paper at this time.
Variable-temperature binding studies are used to evaluate the thermodynamics of molecular recognition of a variety of guests by macrocyclic, cyclophane hosts. In both organic (CDCl₃) and aqueous media, significant heat capacity effects are evident. Curvature in the van't Hoff plots can be well-modeled by assuming a constant value for ΔCₚ⁰, and statistical analysis reveals a meaningful improvement in the correlation when ΔCₚ⁰ is included. Trends in the values for ΔH⁰_ (298) and ΔS⁰_ (298) reveal a predominantly enthalpic origin for the "cation-π" effect, which involves the stabilization of a positive charge by the electron-rich face of an aromatic ring.
Stauffer et al. (Sun,) studied this question.