Highly sensitive and selective Fe3+ detection by a water-stable Tb3+-doped nickel coordination polymer-based turn-off fluorescence sensor

A Nickel coordination polymer, [Ni-2(HBTC)(2)(NH2CONH2)(2)(H2O)(4)] center dot 3H(2)O (Ni-BTC, H3BTC = 1,3,5-benzenetricarboxylic acid) was synthesized under ionothermal condition, which acted as parent framework to load Ln(3+) (Ln(3+) = Tb3+, Eu3+, Dy3+ and Sm3+) respectively from the ethanol solutions to prepare Ln3+-doped Ni-BTC (Ln3+@Ni-BTC) composites. The screened Tb3+@Ni-BTC displays bright green fluorescence and water stability, which was used to detect seventeen metal cations in their aqueous solutions, including Fe3+ , Al3+ , Li+ , Na+ , K+ , Ag+ , Mg2+, Ca2+ , Ba2+ , Zn2+, Mn2+, Cd2+, Co2+, Ni2+, Cr3+, Cu2+ and Hg2+. Tb3+@Ni-BTC showed a rapid fluorescence quenching to Fe3+. The sensitivity tests of Tb3+@Ni-BTC toward CFe3+ detection inferred a linear response of I-0/I = 103673.4 x CFe3+ + 1.0844 at Fe3+ concentration ranging 1 x 10(-6) -4 x 10(-5) mol L-1 and limit of detection (LOD) calculated as 2.82 mu mol L-1. Anti-inference tests also demonstrated Fe3+ cannot be interfered by other sixteen single metal cations or all metal cations as co-existed ions. The emission intensities at 543 nm of Tb3+ (D-5(4)) can completely recover during the ten-time quenching-recovery cycle in the durability test. Tb3+@Ni-BTC can be regarded as a candidate of quantitative fluorescence sensor to Fe3+ detection with high sensitivity, anti-interference, rapid response and durability.