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Bulkiness Makes the Difference: Modulating Solid-State Emission of Anticoronavirus Active Pt(tpy)C(O)NHCH2R Complexes
Mateusz Klarek1, Daria Wysocka1, Judith Füllborn-Ott2
1University of Łódź, Faculty of Chemistry , Department of Organic Chemistry, Tamka 12, Łódź91-403, Poland.
Inorganic Chemistry
|July 17, 2026
Summary
Bulky substituents on platinum(II) terpyridine complexes tune solid-state photoluminescence by altering platinum-platinum interactions. Ligand design influences aggregation and emission, with one complex showing antiviral activity.
Area of Science:
- Coordination Chemistry
- Materials Science
- Photophysics
Background:
- Solid-state photoluminescence (PL) in Pt(II) terpyridine (tpy) complexes is governed by intermolecular Pt···Pt metallophilic interactions.
- These interactions can be modulated by introducing bulky substituents onto the tpy ligand, affecting the emission properties.
Purpose of the Study:
- To design and synthesize novel Pt(II) tpy complexes, specifically [L1PtCl]PF6 and [L2PtCl]PF6, incorporating propargyl (L1) and 1-adamantyl (L2) substituents.
- To investigate the impact of these substituents on the solid-state photoluminescence and aggregation behavior of the complexes.
- To evaluate the antiviral potential of the synthesized complexes.
Main Methods:
- Synthesis of Pt(II) 2,2':6',2"-tpy complexes with varying substituents.
- Photoluminescence spectroscopy at different temperatures (293 K and 77 K) to analyze emission spectra.
- Structural analysis inferred from PL spectral characteristics, particularly the presence or absence of vibronic resolution and emission wavelengths.
- Antiviral activity assays against HCoV-OC43 and influenza A viruses.
Main Results:
- At 293 K, both complexes exhibited broad, featureless orange-red emission around 650 nm, indicative of 3MMLCT excited states and short Pt···Pt contacts.
- At 77 K, distinct PL spectra were observed: [L1PtCl]PF6 emitted at 688 nm, while [L2PtCl]PF6 emitted at 665 nm, suggesting differences in aggregation due to ligand bulk.
- The monohydrate [L2PtCl]PF6·H2O displayed vibronically resolved 3MMLCT+3LC emission (567 nm at 293 K, 560 nm at 77 K), indicating Pt···Pt contact relaxation due to water.
- [L2PtCl]PF6 demonstrated superior antiviral activity against HCoV-OC43 and influenza A compared to [L1PtCl]PF6.
Conclusions:
- Steric hindrance from bulky ligands like 1-adamantyl in Pt(II) tpy complexes can disrupt Pt···Pt contacts, influencing solid-state photoluminescence.
- Water molecules can mediate the relaxation of Pt···Pt contacts, leading to altered emission characteristics.
- [L2PtCl]PF6 exhibits promising antiviral properties, warranting further investigation.
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