Double-Oxalate-Bridging Tetralanthanide Containing Divacant Lindqvist Isopolytungstates with an Energy Transfer Mechanism and Luminous Color Adjustablility Through Eu 3+ /Tb 3+ Codoping

A double-oxalate-bridging tetra-Gd containing divacant Lindqvist dimeric isopolytungtate Na [Gd (C O )(H O) (OH)W O ] ·30H O ( ) was obtained based on the reaction of Na WO ·2H O, H C O , and GdCl in aqueous solution. Its dimeric polyoxoanion is established by two divacant Lindqvist [W O ] segments connected by a rectangular tetra-nuclearity [Gd (C O ) (H O) (OH) ] cluster. Notably, neighboring trinuclear [Na O (H O) ] clusters are interconnected to construct a picturesque 1-D sinusoidal Na-O cluster chain. The most outstanding characteristic is that 1-D sinusoidal Na-O cluster chains combine [Gd (C O )(H O) (OH)W O ] polyoxoanions together, giving rise to an intriguing 3-D extended porous framework. The red emitter Eu ions and green emitter Tb ions are first codoped into to substitute Gd ions for the exploration of the energy transfer (ET) mechanism between Eu and Tb ions and the color-tunable PL property in the isopolytungtate system. The PL emission spectra and decay lifetime measurements of the Eu /Tb codoped system illustrate that under excitation at 370 nm, Tb ions can transfer energy to Eu ions. When the molar concentration of Tb ions is fixed at 0.9 and that of the Eu ions gradually increases from 0.01 to 0.08, the calculated ET efficiency (η ) from Tb to Eu ions increases from 7.9% for to 67.3% for . The energy transfer mechanism (Tb → Eu ) is a nonradiative dipole dipole interaction. Furthermore, upon excitation at 370 nm, and show visible red- and green-emitting lights, respectively. When codoping trace amounts of Eu ions in , under excitation at 370 nm, displays near white-light emission.