Calix[4]arene-based ditopic receptors for simultaneous recognition of fluoride and cobalt(II) ions

A series of calix[4]arene based ditopic receptors possessing bipyridyl and hydrazone units have been synthesized and evaluated for ionic recognition. It has been observed that the synthesized derivatives function as allosteric receptors for simultaneous recognition of Co2+and F− ions through non-covalent interactions. Significant bathochromic shifts in the UV–visible spectrum with a profound colour change promise their use to engineer novel applications.