title: Preparation and photophysical studies of [Ln(hfac)3DPEPO], Ln = Eu, Tb, Yb, Nd, Gd; interpretation of total photoluminescence quantum yields.
abstract: Synthesis and photophysical characterisation of [Ln(hfac)3DPEPO] complexes (with Ln = Eu, Tb, Yb, Nd, Gd) has been carried out to investigate the factors responsible for the variation in total photoluminescence quantum yield within this family of emissive lanthanide complexes. Electronic absorption and emission spectroscopy, in conjunction with DFT calculations of the excited state of the Eu complex, elucidate the role of each ligand in the sensitisation of the lanthanide through the antenna effect. The X-ray crystal structure of [Gd(hfac)3DPEPO] has been determined and shows an 8-coordinate environment around the Gd and a ten-membered chelate ring involving the DPEPO ligand. Total photoluminescence quantum yields were measured to be 6%, 1% and 2% for Ln = Tb, Nd and Yb, respectively, in comparison with around 80% for Ln = Eu. The lower quantum yield for Nd and Yb, compared with Eu, can be attributed to more efficient quenching of the excited Ln state by high-energy oscillations within the ligands, whereas the lower quantum yield for Tb is assigned to a combination of poor energy transfer from the ligand excited state to the Tb and longer radiative lifetime.
authors.affiliation: School of Chemistry and EaStCHEM Research School, University of Edinburgh, West Mains Road, Edinburgh, EH9 3JJ, UK.
authors.forename: Martina
authors.initials: M
authors.lastname: Congiu
authors.forename: Mohamed
authors.initials: M
authors.lastname: Alamiry
authors.forename: Omar
authors.initials: O
authors.lastname: Moudam
authors.forename: Serena
authors.initials: S
authors.lastname: Ciorba
authors.forename: Patricia R
authors.initials: PR
authors.lastname: Richardson
authors.forename: Laurent
authors.initials: L
authors.lastname: Maron
authors.forename: Anita C
authors.initials: AC
authors.lastname: Jones
authors.forename: Bryce S
authors.initials: BS
authors.lastname: Richards
authors.forename: Neil
authors.initials: N
authors.lastname: Robertson
mesh_terms: D018360:Crystallography, X-Ray; D028581:Lanthanoid Series Elements / Q000737:chemistry*; D049449:Luminescence; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D055668:Photochemical Processes; D011789:Quantum Theory
chemical_list: D028581:Lanthanoid Series Elements; D009942:Organometallic Compounds