Abstract
The binding of the polyaromatic guest, 3,6-diaminoacridine (Proflavine) to cucurbit[n]uril (CB[n]) where n = 6, 7 and 8 has been studied by fluorescence spectrophotometry and binding constants determined using a least squares fitting method. Titration of CB[8] into a solution of Proflavine results in a 95% decrease in fluorescence up to a CB[8] to Proflavine ratio of 2:1. From the induced fluorescence spectra a binding constant of 1.9 times 107 M- 1 was determined. When Proflavine is titrated into a solution of CB[8] a similar binding constant is calculated (1.3 times 107 M- 1). Titration of CB[6] into a solution of Proflavine yields a decrease in fluorescence of 18-20%, but no binding is observed beyond what is seen within experimental error. Finally, titration of CB[7] into a solution of Proflavine results in an increase in fluorescence (32%) and a blue-shift of the emission wavelength from 509 nm to 485 nm. From the induced fluorescence spectra a binding constant of 1.65 times 107 M- 1 was determined. From 1H NMR it appears that the decrease in fluorescence for Proflavine with CB[6] and CB[8] is due to collisional quenching, whereas the increase in fluorescence with CB[7] may be due to rotational restriction.
Original language | English |
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Pages (from-to) | 475-484 |
Number of pages | 9 |
Journal | Supramolecular Chemistry |
Volume | 19 |
Issue number | 7 |
DOIs | |
Publication status | Published - 2007 |
Keywords
- proflavine
- DNA intercalator
- cucurbituril
- flourescence spectroscopy
- binding constant
- 1H NMR