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 {[Zn2(3-bpep)2(2,5-FDC)2]·1.5H2O}n (1), which undergoes regioselective photocycloaddition to yield another 1D coordination polymer {[Zn2(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 °C. Such a photocycloaddition/thermocycloreversion cycle results in an interesting reversible dielectric switching.