Rigidly linked dinuclear platinum() complexes showing intense, excimer-like, near-infrared luminescence

Many luminescent platinum( ii ) complexes undergo face-to-face interactions between neighbouring molecules, leading to bimolecular excited states that may emit at lower energy (dimers and/or excimers). Detailed photophysical studies are reported on dinuclear complexes, in which two NCN-coordinated P...

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Bibliographic Details
Published in:Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2023-11, Vol.11 (43), p.15335-15346
Main Authors: Pander, Piotr, Walden, Melissa T, Salthouse, Rebecca J, Sil, Amit, Yufit, Dmitry S, Dias, Fernando B, Williams, J. A. Gareth
Format: Article
Language:English
Subjects:
Emission
Excimers
Ligands
Low concentrations
Molecular structure
Photoluminescence
Platinum
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Summary:Many luminescent platinum( ii ) complexes undergo face-to-face interactions between neighbouring molecules, leading to bimolecular excited states that may emit at lower energy (dimers and/or excimers). Detailed photophysical studies are reported on dinuclear complexes, in which two NCN-coordinated Pt( ii ) units are covalently linked by a xanthene such that intramolecular formation of such dimeric or excimeric states is possible. These complexes display strong excimer-like photoluminescence at low concentrations where their monometallic analogues do not. However, a striking difference emerges between complexes where the Pt(NCN) units are directly connected to the xanthene through the tridentate ligand (denoted Class a) and a new class of compounds reported here (Class b) in which the attachment is through a monodentate acetylide ligand. The former require a substantial geometrical rearrangement to move the metal centres of the Pt(NCN) units to a distance short enough to form excimer-like states. The latter require only a small deformation. Consequently, Class a compounds display negligible excimer-like emission in solid films, as the rigid environment hinders the requisite geometric rearrangement. Class b complexes, in contrast, display strong excimer-like emission in film, even at very low loadings. The new dinuclear molecular architecture may thus offer new opportunities in the quest for efficient NIR-emitting devices. Xanthenes appended with two NCN-coordinated Pt( ii ) ions form NIR-emitting "intramolecular excimers". The xanthene-to-complex linker is crucial in determining photophysical behaviour.
ISSN:2050-7526
2050-7534
DOI:10.1039/d3tc03432a