Maria Buthelezi - Molecular association of benzene with a new cyclophane receptor

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      Publication Details (including relevant citation   information):

      Journal of   Inclusion Phenomena and Macrocyclic   Chemistry, 61,   2008, 347



      Host/guest interactions in the   cyclophane-2/benzene system have been   investigated by absorption and fluorescence spectroscopy in   dichloromethane. The cyclophane serves as a host and the benzene   as a guest. Absorption and fluorescence titration experiments are   carried out by holding either the concentration of the host or   guest constant while varying the concentration of the other   component. When the concentration of benzene is kept constant, an   isostilbic point at 288 nm is observed in the fluorescence   spectral data, suggesting that only two absorbing species are   present in equilibrium. Keeping the concentration of   cyclophane-2 constant while increasing the   concentration of benzene results in a hyposchromic shift of the   emission peaks in the range 275–360 nm. The shift is attributed   to interaction of the cyclophane with benzene. The average   association constant of cyclophane-2 with   benzene, K a = 425 ± 54 M−1,   obtains from fitting the absorption and the fluorescence spectral   data to the Bourson et al. equation using non-linear regression   analysis.

      Keywords Aromatic compounds -   Association constant - Cyclophane - Host/guest complexation

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