Association constant of β-cyclodextrin with carboranes, adamantane, and their derivatives using displacement binding technique

The association constants (K-a') of unsubstituted o-, m-, and p-carborane, as well as that of adamantane, with beta-Cyclodextrin are reported for the first time using displacement binding in an aqueous solution. The K-a' of several derivatives of these species are reported as well. The limitations of the displacement binding technique are also explored. Although hydrophobicity plays a major role in the association with beta-CD, unsubstituted o-carborane, which is the least hydrophobic of the carborane derivatives, exhibits the highest K-a' of 2690 M-1. The K-a' values for the m-and p-carborane isomers decrease with decreasing dipole moment (1830 M-1 and 1560 M-1 respectively). Unsubstituted adamantane exhibits a K-a' value lower than each of the three carborane isomers at 1410 M-1. [GRAPHICS] .