1-D Chain lanthanide coordination polymers based on mixed 2,4-dichlorophenoxyacetate and 1,10-phenanthroline ligands: crystal structures and luminescent properties

Abstract

Two new isostructural 1-D lanthanide coordination polymers, {[Ln(2,4-dcp)₃(phen)] _n [(Ln = Eu (1); Tb (2)], [2,4-dcp = 2,4-dichlorophenoxyacetate, phen = 1,10-phenanthroline], were obtained under hydrothermal conditions and characterized by IR spectroscopy, elemental analyses, thermogravimetry analyses, powder X-ray diffraction, and single-crystal X-ray diffraction. Both structures exhibit similar 1-D infinite chains with a {Ln₂(2,4-dcp)₆(phen)₂} dimeric repeat unit, with lanthanides in an eight-coordinate environment. The results of thermal analysis indicate that 1 and 2 are quite stable to heat. 3-D fluorescence spectra of 1 and 2 were detected at room temperature under excitation and the emission wavelengths of 250–460 nm and 420–750 nm with the same interval of 5 nm, respectively. Interestingly, 1 and 2 possess longer fluorescence lifetimes than other complexes (τ = 1.61 ms for 1 at 611 nm; 1.79 ms for 2 at 543 nm).

Keywords:

• Lanthanide coordination polymers
• Hydrothermal synthesis
• Crystal structures
• Luminescent properties

Acknowledgments

We are thankful for financial support of this work provided by the Zhaoqing University with doctoral start-up fund (611268), the Science and Technology Planning Project of Zhaoqing City (2012G013), the Guangdong Medical College (B2010009), Foundation for Distinguished Young Talents in Higher Education of Guangdong, China (LYM11069), Technologies R&D program of Zhanjiang (2011C3108013).