Two Water-Stable Zn(II) Coordination Polymers as Luminescent Sensors for Detection of Uric Acid in Serum, MnO4–, and Cr(VI) Oxo-Anions in Tap Water

Two novel coordination polymers (CPs), [Zn2(μ-OH)2(μ-1,5-NDS-κ2O:O′)(μ-Mbimb-κ2N:N′)]n(1) and {[Zn(CH3COO-κ1O)(μ-bbimb-κ2N:N′)1.5](1,5-NDS)0.5}n(2), were synthesized by hydrothermal reaction of Zn(Ac)2·2H2O with 1,5-naphthalenedisulfonate (1,5-NDS2–), 1,4-bis(2-methyl-1H-imidazole-1-yl)butane (Mbimb), or 1,4-bis(1H-benzimidazol-1-yl)butane (bbimb). In the crystal structure of 1, the Zn(II) centers are connected by μ-OH–anions into an infinite –[Zn(OH)]n– chain, which is further linked by Mbimb and 1,5-NDS2–to form a 3D dianetwork. In 2, the Zn(II) centers are linked by bbimb ligands into a 2D (6,3) brick wall layer with Ac–as dangling arms threaded into the space of adjacent layers, resulting in a 2D → 3D polythreading structure. Luminescent studies reveal that both CPs have excellent luminescence stability and can selectively detect uric acid (UA), MnO4–, and Cr(VI) oxo-anions in aqueous solutions with high quenching efficiency. The limits of detection toward UA, MnO4–, CrO42–, and Cr2O72–are 0.46, 4.33, 5.50, and 1.60 μM for CP 1and 5.63, 2.84, 7.60, and 2.90 μM for CP 2, respectively. Moreover, the two CPs can also serve as luminescence sensors to detect UA in serum and MnO4–and Cr(VI) oxo-anions in tap water. The luminescent films of the CPs were also prepared for visual detection of UA, MnO4–, CrO42–, and Cr2O72–with the naked eye.