W-shaped 1,3-di(2,4-dicarboxyphenyl)benzene based lanthanide coordination polymers with tunable white light emission

Abstract

A series of trinuclear coordination polymers (CPs), {[Ln_1.5(DDB)(FA)_0.5(H₂O)_2.5]·6H₂O}_n (Ln = Sm for 1, Eu for 2, Tb for 3, Dy for 4), have been constructed from Ln cations and 1,3-di(2,4-dicarboxyphenyl)benzene (H₄DDB) with the help of in situ generation of formate anions under solvothermal reactions. Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, powder X-ray diffraction (PXRD), and thermogravimetric (TG) analyses. Complexes of 1–4 exhibit the unprecedented (3,8)-connected 3D architectures with the Schlafli Symbol of (4.5²)₂(4².5¹².6⁶.7⁵.8³), based on the trinuclear [Ln₃(COO)₆] SBUs. Besides, luminescence investigations indicated that 1 and 4 show ligand-based fluorescence, while 2 and 3 show typical red or green emission with 4f–4f transitions for Ln ions. White light emission can be achieved by doping Dy ions into the Eu complex.