Novel 2,2′-bipyridine-modified calix[4]arenes: ratiometric fluorescent chemosensors for Zn2+ ion

Two calix[4]arene derivatives with modified bipyridine as binding sites have been designed and synthesized. Compounds 1 and 2 are the first 2,2′-bipyridine-modified calix[4]arene-based sensors that can detect Zn2+ selectively with respect to ratiometric fluorescent changes and red shift. A binuclear complex structure has been demonstrated in the binding modes of 1-Zn2+ and 2-Zn2+ complexes.