Kim, Sung Kuk Lee, Seoung Ho Lee, Ji Yeon Lee, Jin Yong Bartsch, Richard A. Kim, Jong Seung An Excimer-Based, Binuclear, On−Off Switchable Calix[4]crown Chemosensor A new fluorescent chemosensor with two different types of cation binding sites on the lower rims of a 1,3-alternate calix[4]arene (<b>1</b>) is synthesized. Two pyrene moieties linked to a cation recognition unit composed of two amide groups form a strong excimer in solution. For <b>1</b>, the excimer fluorescence is quenched by Pb<sup>2+</sup>, but revived by addition of K<sup>+</sup> to the Pb<sup>2+</sup> ligand complex. Thus, metal ion exchange produces an on−off switchable, fluorescent chemosensor. Computational results show that the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbitals (LUMO) of the two pyrene moieties interact under UV irradiation of <b>1</b> and its K<sup>+</sup> complex, while such HOMO−LUMO interactions are absent in the Pb<sup>2+</sup> complex. HOMO;Computational results show;amide groups form;excimer;metal ion exchange;UV;cation binding sites;cation recognition unit;Pb;LUMO;chemosensor;pyrene moieties 2004-12-22
    https://acs.figshare.com/articles/journal_contribution/An_Excimer_Based_Binuclear_On_Off_Switchable_Calix_4_crown_Chemosensor/3311215
10.1021/ja045689c.s001