Fluorescent Change Of Pyreneamide Bearing Calix[4]crown-5: Inhibit Logic Gate In K+-induced Complexation

Abstract

The fluorescence excimer emission of 1 is found to be enhanced upon the addition of K+ ion which is due to a conformational change of the ligand to have a more efficient π–π* interaction of two pyrenes. By contrast, no fluorescence change of 1 was observed in the anion binding test with F− , Cl− , Br− , I− , , , and as their tetrabutylammonium salts in MeCN. Interestingly, it was observed that the excimer emission of the two pyrenes decreases upon the addition of or in the 1√K+ complex solution. This is presumably due to a conformational change of the ligand by K+ ion binding, which induces the better conformation of two facing pyrene amides to selectively adopt or ion. This allosterical anion complexation could be applicable for NOR and INHIBIT (INH) logic gates.