Three zinc metal-organic frameworks (MOFs), {ZnL(chd)}n (1), {[Zn(L)0.5(oba)]·DMF·H2O}n (2) and {[Zn(L)0.5(sdb)]·H2O}n (3) [L = E,E-2,5-dihexyloxy-1,4-bis-(2-pyridin-vinyl)-benzene; H2chd = 1,4-cyclohexanedicarboxylic acid, H2oba = 4,4'-oxybisbenzoic acid, H2sdb = 4,4'-sulfonyldibenzoic acid], have been hydrothermally synthesized. We explored their applications in detecting ions, and the result shows that they all show highly selective sensing for Fe3+ and Cr2O72- ions.