A supramolecular microporous network of zinc(II) coordination polymer for highly selective fluorescent detection of Pb²⁺

Abstract

A hydrogen bonded microporous network with Lewis basic N sites, viz., {[Zn(TZ-HIP)(HPYTZ)(H2O)2]·3H₂O}_n [TZ-HIP = 5-(tetrazol-5-yl)isophthalic acid, HPYTZ = 3,5-di(4-pyridyl)-1H-1,2,4- triazolate ligand] has been obtained from the dual ligand system of polydentate N-heterocyclic carboxylate and dipyridyl-type ligands. Single crystal X-ray diffraction analysis shows that the adjacent Zn(II) centers are bridged by HTZ-H₂IP ligand to form 1D chain with HPYTZ molecules as free lateral arms. The paralleled chains are connected by H-bonding interactions to produce the 3D microporous network with 1D pores. It is interesting that the uncoordinated N atoms (Lewis base sites) pores cause Pb²⁺ ions to produce a remarkably enhancing effect on the luminescent intensity of the zinc complex with high sensitivity in the detection range of 10^-3-10^-5mol L^-1 concentration limit. This coordination polymer may be used as a sensing material for developing a highly selective and sensitive Pb²⁺ sensor in the biological and environmental materials.