Lanthanide Complexes Constructed by 2,2′-Oxybis(benzoic acid) and 1H-Imidazo[4,5-f] [1,10]-phenanthroline: Fluorescence and Fluorescent Sensing for NH3

New complexes [Ln(2)(2,2'-Hoba)(6)(IP)(2) {Ln = Eu (1), Tb (2), 2, 2'-H(2)oba = 2, 2'-oxybis ( benzoic acid), IP = 1H-imidazo [4,5-f ] [1,10]-phenanthroline}, [ Ln(2)(2,2'-oba )(3)(IP)] (Ln = Eu (3), Tb (4)] and [Eu-2(2,2'-oba )(3)(TPP) (H2O)] (5) {TPP = tetrapyrido [2, 3-a 3', 2'-c: 2 '', 3 ''-h: 3'''', 2''''-j] phenazine} were synthesized under hydrothermal condition and characterized by X-ray single crystal diffraction (XRD), IR spectroscopy and elemental analysis. Complexes 1 and 2 have dinuclear molecular structures, complexes 3 and 4 reveal 1D line structure and complex 5 features a 3D structure. The recognition of complexes 1-5 for NH3 was discussed with method of fluorescence spectroscopy. The results showed that they had highly sensitivity for NH3 via a fluorescence quenching mechanism, with the quenching rates of 82. 05%- 97. 49%. The recognition of complex 1 for NH3 and some metal ions (Ca2+, K+, Mg2+, Na+, Zn2+, Cu2+, Cr3+, Ba2+, Al3+, Mn2+, Ni2+ and Pb2+) was studied. Luminescent investigation revealed that complex 1 could detect NH 3 with relatively high sensitivity in contrast to some metal ions, even at pH = 4.0-8.0. The respective addition of some cations (Zn2+, Al3+ or Cr3+) into the complex 1-NH3 system resulted in obvious fluorescent variation at 618 nm, with the fluorescent intensity at 618 nm increasing rapidly and then decreasing and a new peak occurring at 430-510 nm. Because of the synergy influence of NH3 and Zn2+ (Al3+ or Cr3+), if Zn2+ (Al3+ or Cr3+) solution was added into 1-NH 3 system, the emission peak among 430-510 nm came into being. This showed that complex 1, NH3 and Zn2+ (Al3+ or Cr3+) had some combined action. The primary results showed that complex 1 had some sensitive recognition capability for NH3, and this action was impacted by some metal ions.