Synthesis, structural modelling and luminescence of a novel erbium(III) complex with 2,4-nonanedione and 2,2′-bipyridine ligands for chitosan matrices doping

•A highly coordinated Er(III) complex has been synthesized and characterized.•Efficient sensitization by antenna effect has been confirmed.•Ground state geometry determined by Sparkle/PM7 semiempirical calculations.•Chitosan doped with the material shows NIR emission with 85 nm FWHM.

We report the synthesis, the Sparkle/PM7 semi-empirical quantum model for the ground state geometry and the absorption/luminescent properties of the Er3+ ternary complex [Er(nd)3(bipy)] (where Hnd is 2,4-nonanedione and bipy is 2,2′-bipyridine). The solid-state electronic absorption spectra and the photoluminescent spectra show long-wavelength 4f–4f transitions which provide a potential use of the compound as a NIR-emitting material for the doping of polymer-based matrices for waveguides or for bio-analytical applications. The dispersion of the novel complex in a biocompatible chitosan film has been assessed.