Three Cd(II) iso-frameworks {[Cd(BIPA)(IPA)]center dot DMF}(n) (1), I[Cd(BIPA)(HIPA)].DMFL (2), and {[Cd(BIPA)(NIPA)]center dot 2H(2)O}(n) (3) were synthesized from the self -assembly of the BIPA ligand (BIPA = bis(4-(1H-imidazol-1-yOphenyl)amine) and different carboxylic ligands (H(2)IPA = isophthalic acid, H(2)HIPA = 5-hydroxyisophthalic acid, H(2)NIPA = S-nitroisophthalic acid) with Cd(II), which have amino groups, amino and phenolic hydroxyl groups, and amino and nitro groups, respectively. Both 1 and 2 exhibit CO2 uptakes of more than 20 wt %, indicating that amino and phenolic hydroxyl functionalized groups are beneficial to CO2 adsorption. Their applications and mechanisms in detecting metal ions were researched. The results exhibit that 1 and 2 are dual -responsive photoluminescent sensors for He' and Pb" ions with low detection concentration and high quenching constant. Besides, like most MOFs, 3 can detect a trace quantity of Fe3+ and Cu2+.