Structure, color-tunable luminescence, and UV-vis/NIR benzaldehyde detection of lanthanide coordination polymers based on two fluorinated ligands

Abstract

Herein, by incorporating a strongly luminescent emissive ancillary fluorinated β-diketone ligand into lanthanide coordination polymers (LnCPs), a series of LnCPs, i.e. [Ln(tfbdc)_0.5(bta)₂(CH₃OH)₂]·CH₃OH [Ln = La (1), Pr (2), Nd (3), Sm (4), and Eu (5)] and [Ln(tfbdc)_0.5(bta)₂(CH₃OH)] [Ln = Tb (6), Dy (7), Ho (8), Er (9), and Yb (10)], have been isolated by reactions of LnCl₃·6H₂O with H₂tfbdc (2,3,5,6-tetrafluoroterephthalic acid) and bta (benzoyltrifluoroacetone). Single-crystal X-ray diffraction analysis reveals that the complexes 1–10 exhibit a 1D zigzag chain structure, which differs from the 2D or 3D structure of the reported tfbdc-Ln complexes due to the introduction of the bta ligand. Moreover, the C–F bonds located in the fluorinated tfbdc and bta ligands can weaken the vibrational quenching effect on the luminescence properties partly and finally realize enhanced luminescence. Some systematic studies have been implemented to analyze the photoluminescence of these complexes. As an exception, the complexes 1–10 exhibit impressive UV-visible or NIR luminescence. By carefully regulating the relative intensity of the blue, green, and red (RGB) emission, a three-component white-light emitting complex 11 (La–Eu–Tb) has been realized. Moreover, the complexes 6 and 10 exhibit high sensitivity and selectivity of the UV-visible and NIR luminescence response to benzaldehyde, which act as promising luminescent sensors for the detection of benzaldehyde.