Rare-earth coordination polymers with multimodal luminescence on the nano-, micro-, and milli-second time scales
Marius Jakoby,
Carolin Beil,
Pariya Nazari,
Bryce S. Richards,
Michael Seitz,
Andrey Turshatov,
Ian A. Howard
Affiliations
Marius Jakoby
Institute of Microstructure Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
Carolin Beil
Institute of Inorganic Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
Pariya Nazari
Institute of Microstructure Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
Bryce S. Richards
Institute of Microstructure Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany; Light Technology Institute, Karlsruhe Institute of Technology, Engesserstrasse 13, 76131 Karlsruhe, Germany
Michael Seitz
Institute of Inorganic Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany; Corresponding author
Andrey Turshatov
Institute of Microstructure Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany; Corresponding author
Ian A. Howard
Institute of Microstructure Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany; Light Technology Institute, Karlsruhe Institute of Technology, Engesserstrasse 13, 76131 Karlsruhe, Germany; Corresponding author
Summary: We present a coordination polymer based on rare-earth metal centers and carboxylated 4,4′-diphenyl-2,2′-bipyridine ligands. We investigate Y3+, Lu3+, Eu3+, and a statistical mixture of Y3+ with Eu3+ as metal centers. When Y3+ or Lu3+ is exclusively present in the coordination polymer, biluminescence from the ligand is observed: violet emission from the singlet state (417 nm, 0.9 ns lifetime) and orange emission from the triplet state (585 nm, 76 ms (Y3+) and 31 ms (Lu3+)). When Eu3+ is present in a statistical mixture with Y3+, red emission from the Eu3+ (611 nm, ∼500μs) is observed in addition to the ligand emissions. We demonstrate that this multi-mode emission is enabled by the immobility of singlet and triplet states on the ligand. Eu3+ only receives energy from adjacent ligands. Meanwhile, in the broad inhomogeneous distribution of ligand energies, higher energy states favor singlet emission, whereas faster intersystem crossing in the more stabilized ligands enhances their contribution to triplet emission.
