‘On–Off’ reversible switch for Fe3+ and F− mimicking XNOR logic function

A new pyrene-appended chemosensor based on thiacalix[4]arene of 1,3-alternate conformation has been synthesised which demonstrates selective optical recognition of Fe3+ and F− in two contrasting modes. The chemosensor behaves as a bifunctional fluorescent switch which mimics the performance of an exclusive-NOR (XNOR) logic gate with chemical inputs of Fe3+ and F− ions.