Abstract
The effects of <i>t</i>-butyl (TB) compounds on the formation of β-cyclodextrin (CD)/pyrene complexes have been examined by monitoring changes in the fluorescence I/III band ratio of 1.0 x 10<sup>-7</sup> M pyrene in 0.075 M of the <i>t</i>-butyl compounds and in various concentrations of β-CD in a solvent mixture consisting of 60% v/v methanol/40% water solution. For the compounds tested, the strongest effects were observed in the presence of the following (in decreasing order): TB-carbamate, TB-carbazate, TB-(<i>N</i>-hydroxy) carbamate, TB-(N-butoxy carbonyl) glycine, and TB-formate. In terms of enhancement of the pyrene/β-CD binding constant, all exhibited effects stronger than those previously reported for <i>t</i>-butyl alcohol. In contrast, TB-amine, TB-acetic acid, and TB-acetoacetate exhibited very little effect. There appears to be a relationship between the chemical structure of the modifier molecules and the magnitude of their concomitant effects on the I/III ratio. In fact, the <i>t</i>-butyl modifiers which exhibited moderate, to strong effects have a common caboxy, -C-O-, skeleton attached to the <i>t</i>-butyl moiety in their general structure: (CH<sub>3</sub>)<sub>3</sub>C-O-R. The modifier effect was also found to be independent of the pH of the solutions. A detailed explanation has been offered for the observed changes in the I/III ratio relative to <i>t</i>-butyl functionalities.
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