Luminescent coordination polymers constructed using a mixed-ligand strategy for highly selective luminescence sensing of nitrobenzene, Fe3+ and Cr2O72− ions and photodegradation of rhodamine B

Abstract

Using a mixed ligand strategy, ten new luminescent coordination polymers (LCPs), namely, [Cd(IPA-NH₂)(Htpim)]_n (1), [Mn(IPA-NH₂)(Htpim)]_n (2), [Zn(IPA-OH)(Htpim)]_n (3), [Cd(IPA-OH)(Htpim)]_n (4), {[Zn(Htpim)₂(H₂O)₂](IPA-OH)}_n (5), {[Cd(Htpim)₂(H₂O)₂](IPA-OH)}_n (6), [Cd(IPA-NO₂)(Htpim)]_n (7), [Zn₂(PMA)(Htpim)₂]_n (8), [Cd₂(PMA)(Htpim)₂]_n (9) and [Cu(H₂PMA)(Htpim)₂(H₂O)]_n (10) (Htpim = 2,4,5-tri(4-pyridyl)-imidazole, H₂IPA-NH₂ = 5-aminoisophthalic acid, H₂IPA-OH = 5-hydroxyisophthalic acid, H₂IPA-NO₂ = 5-nitroisophthalic acid, H₄PMA = 1,2,4,5-benzenetetracarboxylic acid) were constructed. Compounds 1–4 and 7–9 have similar 2D 4⁴ networks, while 5, 6 and 10 show 1D chain structures. The results reveal that the coordination configuration of M(II), carboxylic acids, and coordinated water molecules play pivotal roles in the formation of the final structures. Moreover, the selective luminescence sensing and photocatalytic performances of 1–10 were also studied. Interestingly, they can sensitively detect trace amounts of nitrobenzene (NB), Cr₂O₇²⁻ or Fe³⁺ through luminescence quenching. In addition, 3–10 show high photocatalytic activities toward the degradation of rhodamine B (RhB).