Highly luminescent and stable lanthanide coordination polymers based 2-(3 ',4 '-dicarboxyphenoxy)-benzoic acid: Crystal structure, photoluminescence, white light emission and fluorescence sensing

Abstract

New lanthanide coordination polymers (Ln-CPs), {[Ln(DPBA)(phen)(2)]center dot 2H(2)O}n (Ln = Eu 1, Tb 2, Gd 3), based on a ternary system containing 2-(3',4'-dicarboxyphenoxy)-benzoic acid (H3DPBA) and 1,10-phenanthroline (phen) were hydrothermally prepared. The Ln-CPs exhibit a 1D structure with [LnO(4)N(4)] polyhedra and DPBA ligands, which can be extended to a 3D supramolecular network by water clusters and pi-stacking. The coordination polymers have remarkable thermal stability up to 340 degrees C and solvent stability (in various solvents containing water in the 3-12 pH range). 1, 2, 3 show bright red, green, and blue emissions, respectively. Notably, 1 exhibits a very high photoluminescence quantum yield (PLQY) of 86%, which is among the best values for Ln-CPs. Energy transfer analysis is performed for Ln-CPs by DFT/TD-DFT calculations, solid-state phosphorescence (77 K) and UV-vis absorption spectra of Gd-CP. Favorable photostability of 1 is observed through a UV aging experiment, which shows that the PLQY of 1 maintained 55% of its initial value after 150 h Ultraviolet A (UVA) irradiation, which makes it potentially useful as a light conversion material. In addition, the Gd0.993Eu0.0017Tb0.0053-CP codoped system shows white emission with a high PLQY of 35.09%, which is among the highly ranked as compared with reported white light emissions based on Ln-CPs. This highly luminescent Eu-CP can also be used as a sensitive fluorescence sensor for antibiotic detection in aqueous solution.