In many cases, the binary complex of Scheme 1 is not preferred and a third species may associate. In the most trivial mechanism, ternary complexation sim­ ply serves to modify Scheme 1 by facilitating analyte association, thus improv­ ing detection sensitivity. Luong [256] has capped CDs with tetrakis-benzoic acid porphyrin (2) to increase the hydrophobicity of the cavity and thus enhance the

complexation thermodynamics of polyaromatic hydrocarbons to the CD bucket. Depending largely on chain length, a coincluded alcohol can alternatively affect analyte association by “wedging” a lumophore into the CD [257-262]. In other instances, the residency of a third species can be used to perturb the emission properties of the reporter site within the bucket.