Pander, Piotr, Zaytsev, Andrey, Sil, Amit, Williams, J. A. Gareth, Kozhevnikov, Valery and Dias, Fernando B. (2022) Enhancement of thermally activated delayed fluorescence properties by substitution of ancillary halogen in a multiple resonance-like diplatinum(ii) complex. Journal of Materials Chemistry C, 10 (12). pp. 4851-4860. ISSN 2050-7526
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Abstract
We present an in-depth investigation of the influence of chloro-to-iodo exchange on the thermally activated delayed fluorescence (TADF) of a dinuclear platinum(II) complex featuring monodentate halide ancillary ligands. The complexes are constructed using a ditopic bis-N^C^N-chelating ligand of the form (N^C^N–N^C^N)Pt2X2. The initially formed chloro complex (X = Cl) is readily transformed into the iodo analogue (X = I). The change is found to increase the radiative decay rate constant kr by around 3-fold to 3–4 × 105 s−1. This remarkably high value is comparable with the state-of-the-art iridium(III) organometallic phosphors. The improved luminescence properties of the iodo compound are shown to be due to a smaller singlet–triplet energy gap ΔEST compared to the chloro analogue. Iodide reduces the HOMO–LUMO overlap in a multiple resonance-like orbital structure of the complex. Iodination is therefore the first practical strategy shown to improve the TADF properties of diplatinum(II) complexes. The analogous monoplatinum(II) phosphorescent complex is studied in parallel in order to shed light more generally on the effect of iodo ligands on the triplet and singlet states and on spin–orbit coupling (SOC) in platinum(II) complexes.
| Item Type: | Article |
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| Additional Information: | Funding information: We thank EPSRC (grant refs EP/S012788/1 and EP/S01280X) for support of this work. We are grateful to Dr Dmitry Yufit at Durham Chemistry for determining the crystal structure of complex 3 and for his continued assistance with crystallography. The authors thank Dr Gleb Baryshnikov for fruitful discussions. This work made use of the facilities of the Hamilton HPC Service of Durham University. |
| Subjects: | F100 Chemistry F200 Materials Science |
| Department: | Faculties > Health and Life Sciences > Applied Sciences |
| Depositing User: | John Coen |
| Date Deposited: | 02 Feb 2022 14:32 |
| Last Modified: | 04 Apr 2022 08:30 |
| URI: | http://nrl.northumbria.ac.uk/id/eprint/48346 |
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