Chemical Forums
Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: Rutherford on September 29, 2013, 07:14:56 AM
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Anthracene exhibits strong fluorescence with emission wavelength centered at 325 nm. Combining the binding selectivity of azacrowns for alkali metal ions and the highly fluorescent anthracene, a metal ion selective fluorescent sensor E has been developed. For comparison studies, the anthracene derivatives F and G shown below were also synthesized. These compounds E, F, and G are almost non-fluorescent in neutral conditions due to the strong photoinduced electron transfer (PET) quenching process arising by donating nitrogen lone-pair electron to the anthracene excited-state.
1) Upon adding aqueous HCl, which compound will exhibit strong fluorescence?
2) By adding one equivalent of potassium acetate into a dilute solution (1ยท10-5 M) of E, F, and G in methanol, respectively, which compound will show the strongest fluorescence?
3) Upon adding one equivalent of metal acetate to a dilute solution of F, which alkali metal acetate will cause the strongest fluorescence?
What is the reasoning here? I need serious help here. I only know that 1) all should exhibit strong fluorescence because the lone pair of nitrogen is converted to a bond pair of N-H bond.
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The solutions are:
2) E;
3) sodium acetate.
Could someone rationalize this?