Abstract
Solid-state photophysical properties of [Ru(bpy)3]2+ are well-studied, whereas those of [Ru(bpy)3]3+ remain elusive. Here, we report ambient-conditions stabilization of [Ru(bpy)3]3+ in an organic-inorganic hybrid crystal, [Ru(bpy)3]2Ag6Br12. Utilizing two-dimensional hexagonal anionic network, (Ag6Br11)n5n-, featuring strong argentophilic interactions, this system stabilizes the spin-bearing low-spin d5 Ru(III) exhibiting unusual room-temperature photoluminescence with three emission peaks (~586, ~612, and ~686 nm), a behavior rarely seen in ruthenium tris(bipyridine) systems. Temperature-dependent and time-resolved photoluminescence measurements reveal average lifetimes of ~10 ns at 300 K across all peaks. The origin of the three emission peaks is identified by time-dependent density functional theory calculations, revealing three doublet ligand-to-metal charge-transfer states to a doublet ground state transitions. The extracted spin-density plot suggests near spin-degeneracy of the dz2, dx2-y2 and dxy orbitals, corroborating trigonal antiprismatic (D3d) microsymmetry. The organic-inorganic hybrid also displays ultralow thermal conductivity (~0.21 W·m-1·K-1 at 480 K), qualifying it as a promising multifunctional material.
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All data supporting the findings of this study are available within this article and its Supplementary Information files. Crystallographic data for the structures reported in this article have been deposited at the Cambridge Crystallographic Data Center (CCDC), under deposition numbers CCDC 2451815 ([Ru(bpy)3]2Ag6Br12 at 150 K), CCDC 2500295 ([Ru(bpy)3]2Ag6Br12 at 298 K), and CCDC 2494053 ([Fe(bpy)3]2Ag6Br12 at 150 K). The data can be obtained free of charge from The Cambridge Crystallographic Data Center via www.ccdc.cam.ac.uk/data_request/cif. All data are available from the corresponding author upon request. Source data are provided with this paper.
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Acknowledgments
Financial support from IISER Pune, India, is gratefully acknowledged. N.H., A.A. and S.S. thank IISER Pune, India and U.B. thanks UGC (India) for providing Research Fellowships. K.T. acknowledges VGST (GRD No. 536) for financial support. N.H. sincerely thanks Rishukumar Panday (IISER Pune) and Pankaj Gupta (IISER Pune) for the help in crystal structure determination and thermal transport measurements, respectively. N.H. also thanks Mini Kalyani (IISER Pune) for useful discussions. N.H. and N.B. specially thank Prof. Angshuman Nag and Anwesha Ray (IISER Pune) for providing the variable-temperature photophysical measurements facility. N. H. and N. B. also thank Prof. Arup Kumar Rath, and Anurag Mitra (CSIR-NCL Pune) for PLQY measurements; and Prof. Partha Hazra, and Madhusudan Dutta (IISER Pune) for additional PL data. K.T. acknowledges C-DAC for providing the computational facility in PARAM Utkarsh. The support and the resources provided by “PARAM Brahma Facility” under the National Supercomputing Mission, Govt. of India, at IISER Pune are gratefully acknowledged.
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N.H. designed and prepared the samples, and carried out most of the experiments with help from T.M.J., A.A., S.S., and U.B., under the guidance of N.B. K.S.A. performed the DFT calculations under the guidance of K.T. N.H. wrote the first draft along with A.A. and S.S., which was finalized by N.B. with inputs from co-authors. N.B. conceived and supervised the research project.
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Hassan, N., Ananthram, K.S., Jose, T.M. et al. Stabilizing [Ru(bpy)3]3+ at room-temperature in a hybrid crystal with unusual luminescence and ultralow thermal conductivity. Nat Commun (2026). https://doi.org/10.1038/s41467-026-72230-0
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DOI: https://doi.org/10.1038/s41467-026-72230-0
