Ln 3 Q 9 as a Molecular Framework for Ion‐Size‐Driven Assembly of Heterolanthanide (Nd, Er, Yb) Multiple Near‐Infrared Emitters

Abstract A unique example of discrete molecular entity Nd y Er x Yb 3−( x + y ) Q 9 ( 1 ) (Q=quinolinolato) containing three different lanthanides simultaneously emitting in three different 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 composition in the Ln 3 Q 9 framework, which contains inequivalent central and terminal coordination sites, has allowed a satisfactory ion‐size‐driven control of molecular speciation close to 90 %. In 1 the central position of the larger Nd ion is well distinguished from the terminal ones of the smaller Yb 3+ and Er 3+ , which are almost “vicariants” as found in the heterobimetallic Er x Yb 3− x Q 9 ( 2 ). The Ln 3 Q 9 molecular architecture, which allows communication between the ions, has proved to afford multiple NIR emission in 1 and 2 , and is promising to develop a variety of multifunctional materials through the variation of the Ln composition.