Synthesis,characterization, and complexing properties of a polymethacrylate bearing pendant macroheterocyclic structures

The synthesis of a polymerizable methacrylate bearing the dibenzo-18-crown-6 moiety ( 5 ) was effected in three steps by condensation of 3,4-dihydroxybenzaldehyde with 1,2-bis2′-(2″-chloroethoxy)ethoxy]benzene ( 2 ), reduction of the resulting 4-formyldibenzo-18-crown-6 ( 3 ) to 4 and subsequent reaction of 4 with methacryloyl chloride. The methacrylate ( 5 ) was polymerized in solution using 2,2′-azobis(isobutyronitrile) (AIBN) as the initiator and gave a solid polymer ( 6 ) having a midrange T_g of 67°C. The polymethacrylate bearing pendant crown-ether structure ( 6 ) was found to effectively complex potassium ions and was clearly more effective in its complexing ability than dibenzo-18-crown-6 ( 7 ) or a polyurethane bearing the dibenzo-18-crown-6 moiety ( 8 ) in the polymer backbone. The subject polymer ( 6 ) was also found to complex and consequently solubilize several metal 7,7,8,8-tetracyanoquinodimethane (TCNQ) salts to give semiconducting compositions. Evidence is given that in the presence of the neutral acceptor molecule, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), the polymethacrylate ( 6 ) acting as a donor, gives rise to a charge-transfer (C/T) complex.