Reversible dielectric switching behavior of a 1D coordination polymer induced by photo and thermal irradiation

Solvothermal reaction of Zn(NO3)(2) with 2,9-bis-(2-pyridine-3-yl-vinyl)-[1,10]phenanthroline (3-bpep) and furan-2,5-dicarboxylic acid (2,5-H2FDC) afforded a one-dimensional (1D) coordination polymer {[Zn-2(3-bpep)(2)(2,5-FDC)(2)]1.5H(2)O}(n) (1), which undergoes regioselective photocycloaddition to yield another 1D coordination polymer {[Zn-2(3-bpep)(trans,rctt-3-bpbpycb)(0.5)(2,5-FDC)(2)]H2O}(n) (2) in a single-crystal-to-single-crystal manner under UV light irradiation. The reverse process from 2 to 1 can be achieved by heating 2 at 240 degrees C. Such a photocycloaddition/thermocycloreversion cycle results in an interesting reversible dielectric switching.