The Dimeric Complex of Beta-Cyclodextrin with 1,13-tridecanedioic acid

The structure of the complex of beta cyclodextrin (βCD) with 1,13-tridecanedioic acid has been determined at low temperature. The compound crystallizes in P1, a = 18.207(6), b = 15.510(5), c = 15.280(6) Å, α = 103.02(3), β = 113.13(3), γ = 99.79(3)° and Dc = 1.339 gcm−3 for Z=1. Refinement based on 13134 observed MoKα reflections led to a final R = 0.076. The diacid molecules thread through two βCD arranged in dimers thus, forming [3]pseudorotax-anes. The aliphatic chain of the guest has a few weak, non-bonded interactions with the host inside the long hydrophobic cavity. However, the end carboxyl groups form several strong H-bonds with the solvent in a fashion similar to other βCD/ carboxylic acid complexes that have similar building blocks as the present one: βCD dimers and carboxylic groups of the guest emerging from their two primary faces. Conversely, in the corresponding complexes with aliphatic monocarboxylic acids the carboxyl groups form carboxylic dimers because they are isolated from the environment inside hydrophobic channels.