Ln3Q9 as a molecular framework for ion-size-driven assembly of Heterolanthanide (Nd, Er, Yb) multiple near-infrared emitters

A unique example of discrete molecular entity NdyErxYb3(x + y)Q9 (1) (Q = quinolinolato) containing three different lanthanides simultaneously emitting in three dif- ferent spectral regions in the NIR, ranging from 900 to 1600 nm, has been synthesized and fully chararacterized. A simple molecular strategy based on tuning metal com- position in the Ln3Q9 framework, which contains inequiva- lent central and terminal coordination sites, has allowed a satisfactory ion-size-driven control of molecular specia- tion close to 90%. In 1 the central position of the larger Nd ion is well distinguished from the terminal ones of the smaller Yb3 + and Er3 + , which are almost “vicariants” as found in the heterobimetallic ErxYb3xQ9 (2). The Ln3Q9 molecular architecture, which allows communication be- tween the ions, has proved to afford multiple NIR emis- sion in 1 and 2, and is promising to develop a variety of multifunctional materials through the variation of the Ln compositio