Maria Buthelezi - Spectroscopic investigations of molecular association of cyclophanes with anthracene

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      Publication Details (including relevant citation   information):

      Arkivoc,   (vii) 2010, 179






      We report an improved synthesis method for the production of   cyclophanes 5, 6, and 7 in higher

      yields of 71, 98, and 99%, respectively, compared to the   previously reported 40, 30, and 70% yields,

    1. Cyclophanes C5, C6, and C7, called corrals, have different   cavity sizes determined by  

      the number of methylene spacers varying from three to five; they   form inclusion complexes with

      neutral aromatic molecules. Therefore, we have studied their   interactions with anthracene (A) using

      absorption, fluorescence, and Fourier transform infrared   spectroscopies. The average association

      constants of each cyclophane with anthracene in dichloromethane   were determined to be (log K)

    1. 4.24 + 0.10, 4.81 + 0.05, and 4.25 + 0.03 for the C5/A, C6/A,   and C7/A systems, respectively.  

      The binding of anthracene is favored by C6 over C5 and C7 in   solution, possibly due to

      increased stability of the equilibrium geometry of the C6/A   complex. Upon complexation low

      frequency spectral shifts for several transitions associated with   anthracene and corral molecules

      were observed. The slight spectral shifts are in accord with weak   intermolecular forces prevalent

      in the studied corral/anthracene complexes.

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