Dual Emission in the Near-Infrared and Visible Regions from a Mixed Cyanido-Bridged Eu III /Nd III (4-OHpy)-Co III Layered Material.

Coordination polymers (CPs) with a dual emission spanning from the visible (vis) to near-infrared (NIR) regions of the electromagnetic spectrum are used for optical sensors, medical diagnostics, and telecommunication technologies. We herein report the synthesis, structural characterization, and optical response of heterometallic cyanido-bridged layered {[Eu x Nd y (4-OHpy) 2 (H 2 O) 3 ][Co(CN) 6 ]} CPs, where 4-OHpy = 4-hydroxypyridine, with a multicolor emission profile across the vis and NIR regions. The crystals show an efficient energy transfer (ET) from the 4-OHpy ligand and the [Co(CN) 6 ] ions to the Eu 3+ and Nd 3+ ions, resulting in an enhanced photoluminescence (PL) efficiency. We study the ET with steady-state and time-resolved PL, reporting an ET between the Ln 3+ centers. The excitation-dependent emission of the mixed Ln 3+ CPs and the control over the PL lifetime yield new insights into the optoelectronic properties of these materials.