Paraquat guest-induced conformational templation of dicarboxylatocalixarenes

Abstract

Proximal dicarboxylatocalix[4]arene 4 and distal dicarboxylatocalix[6]arene 5 have been synthesised in good yields and their complexation abilities towards dicationic paraquat guest 3 have been studied by NMR spectroscopy. Both hosts are able to complex 3 through an induced-fit mechanism, which originates from the conformational flexibility of calixarene macrocycle. A pH-dependent switching system was realised in which guest inclusion can be controlled through an acid/base external stimulus.

Keywords:

• calixarenes
• carboxylatocalixarenes
• paraquat recognition
• induced-fit
• switching system
• association constant

Notes

^†In memory of our dear friend Prof Dmitry Rudkevich.