Thiacalix[4]arene based reconfigurable molecular switches: set-reset memorized sequential device

The fluorescent chemosensors 3, 5 and 7 based on thiacalix[4]arene bearing naphthyl groups have been designed and synthesized. The optical chemosensor 3 based on a thiacalix[4]arene of cone conformation behaves as turn-on optical chemosensor for Fe3+ and F- ions. However, chemosensors 5 and 7 based on a thiacalix[4]arene of 1,3-alternate conformation demonstrate turn-on optical behaviour for Hg2+, F- ions (with receptor 5 as turn-on for K+ ions also) and turn-off behaviour for Fe3+ ions. The simultaneous presence of Fe3+ and Hg2+ or K+ or F- ions results in formulation of reversible on-off switches. Various molecular logic gates developed in response to molecular switching between these chemical inputs have been integrated into sequential logic circuits with memory function in a feedback loop which mimics set-reset molecular level information processing device.