Syntheses, structures and luminescent properties of a series of ladder-shaped [Ln₂Sr₃] heterometal-organic frameworks

Abstract

A series of Ln^III–Sr^II heterometallic coordination polymers formulated as [Ln₂Sr₃(pda)₆(H₂O)₁₈]·nH₂O (Ln = Pr-1, n = 14; Nd-2, n = 12; Sm-3, n = 11; Eu-4, n = 11; Gd-5, n = 16; Tb-6, n = 13; Dy-7, n = 13) were synthesized via assembly of Ln(NO₃)₃·6H₂O, SrCl₂·6H₂O, pyridine-2,6-dicarboxylic acid (H₂pda) and imidazole (im) in H₂O/C₂H₅OH solution. Single crystal X-ray diffraction revealed that they are isostructural. All of these complexes possess ladder-shaped 1-D chain structures. The luminescent properties of Sm-3, Eu-4, Gd-5, Tb-6 and Dy-7 have been investigated. The solid-state quantum yields and the lifetimes of Eu-4 and Tb-6 are also studied.

Keywords:

• Heterometallic complexes
• Alkaline earth metals
• Lanthanide ions
• Lifetime
• Quantum yield

Acknowledgements

The authors appreciate the financial support from Natural Science Foundation of China (21272167 and 21201127), A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institution, Graduate Education Innovation Project in Jiangsu Province (CXZZ12_0808), and Qinghai Science & Technology Department of China (2011-G-208 and 2011-Z-722).