Synthesis, crystal structures and selective luminescence sensing property of Zn(II) coordination polymers based on semi-rigid tricarboxylic acid ligands

Herein, two novel Zn-based coordination polymers [Zn(HL)(1,10-phen)(H2O)]n (1) and [Zn2(HL)2(2,2′-bipy)2]n (2) have been successfully synthesized via solvothermal method by using the semi-rigid tricarboxylic acid ligand (H3L:3-[(1-carboxynaphthalen-2-yl)oxy] phthalic acid) and two different nitrogen-containing heterocyclic ligands (1,10-phenanthroline, 2,2′-bipyridine). A single-crystal X-ray analysis reveals that these two novel Zn-based coordination polymers 1 and 2 exhibit a one dimensional (1D) chain structures. Moreover, two novel Zn-based coordination polymers 1 and 2 exihit excellent fluorescence performances, and selectively recognition response to Ni2+, MnO4−, Cr2O72−, nitrobenzene and nitromethane through the luminescence quenching effects in aqueous solutions. The possible fluorescence recognition mechanism of 1 and 2 toward Ni2+, MnO4−, Cr2O72- are investigated, which may be attribute to the synergistic effects of energy competitive absorption and weak interaction. Whereas the fluorescence quenching behaviors of 1 and 2 toward nitrobenzene and nitromethane, owing to the existence of a strong electron-withdrawing group which can obtain excited-state electrons, and leading to the occurence of electrons transfer. These results indicating that Zn-based coordination polymers have potential application values in fluorescent recognition.