Skip to main content
SpringerLink
Log in

Comprehensive investigation of triplet states of red phosphorescent cationic Ir(III) complexes from cryogenic temperature

  • Original Paper
  • Published:
Journal of the Iranian Chemical Society Aims and scope Submit manuscript

Abstract

In this paper, the detailed photophysical properties of two phosphorescent salts, [Ir(ptpy)2(4,4′-Cl2bpy)]PF6, 1, and [Ir(4-Clppy)2(4,4′-Cl2bpy)]PF6, 2, where ptpy = 2-(p-tolyl) pyridinato; 4,4′-Cl2bpy = 4,4′-dichloro-2,2′-bipyridine, and 4-Clppy = 4-chloro-2-phenylpyridinato) have been studied in CH2Cl2 and PS (polystyrene) film at 77–300 K and in PMMA (polymethyl methacrylate) film in the temperature range of 1.5–300 K. The decay curves are monoexponential in the whole range. Temperature versus the decay time plots in PMMA for complexes display two distinct ranges, one at low temperature (T ≤ 77 K) with ФPL ≈ 100% that corresponds to thermal distribution between the triplet substates, and the other at higher temperatures (T > 77 K) in which the decay time reaches a plateau and the ФPL starts to decrease and amounts to ФPL = 35% and 60% for complexes 1 and 2, respectively, at room temperature. Applying the three-level equation in the first part gives the values of τ(I) = 110 μs, τ(II) = 10.5 μs, τ(III) = 342 ns for complex 1 and τ(I) = 142 μs, τ(II) = 11 μs, τ(III) = 353 ns for complex 2. Obtained zero-field splitting of 105 and 110 cm−1 of T1 state of complexes 1 and 2, respectively, can be assigned to be largely of 3MLCT character of this state. For the second part (T > 77 K) with the contribution of the thermally activated decay processes, we add two additional terms in Eq. (1) to get the decay rate k(Q) = 7.2 × 106 s−1, ∆E(Q-I) = 304 cm−1 for 1 and k(Q) = 4.3 × 106 s−1 and ∆E(Q-I) = 638 cm−1 for 2 which proposed the active role of metal-centered (3MC) triplet excited states in the non-radiative deactivation pathways.

Graphical abstract

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Scheme 1.
Fig. 1
Fig. 2
Fig. 3
Fig. 4

Similar content being viewed by others

References

  1. C. Murawski, K. Leo, M.C. Gather, Efficiency roll-off in organic light-emitting diodes. Adv. Mater. 25(47), 6801–6827 (2013)

    Article  CAS  Google Scholar 

  2. H. Yersin, W. Finkenzeller, Highly efficient OLEDs with phosphorescent materials. Search PubMed. 2007, 1–98 (2008)

    Google Scholar 

  3. H. Yersin, A.F. Rausch, R. Czerwieniec, T. Hofbeck, T. Fischer, The triplet state of organo-transition metal compounds Triplet harvesting and singlet harvesting for efficient OLEDs. Coord. Chem. Rev. 255(21), 2622–2652 (2011)

    Article  CAS  Google Scholar 

  4. J.L. Rodríguez-Redondo, R.D. Costa, E. Ortí, A. Sastre-Santos, H.J. Bolink, F. Fernández-Lázaro, Red-light-emitting electrochemical cell using a polypyridyl iridium (III) polymer. Dalton Trans. 44, 9787–9793 (2009)

    Article  Google Scholar 

  5. R.D. Costa, E. Ortí, H.J. Bolink, S. Graber, C.E. Housecroft, E.C. Constable, Efficient and long-living light-emitting electrochemical cells. Adv. Funct. 20(9), 1511–1520 (2010)

    Article  CAS  Google Scholar 

  6. K.K.W. Lo, K.Y. Zhang, Iridium (III) complexes as therapeutic and bioimaging reagents for cellular applications. RSC adv. 2(32), 12069–12083 (2012)

    Article  CAS  Google Scholar 

  7. C. Ulbricht, B. Beyer, C. Friebe, A. Winter, U.S. Schubert, Recent developments in the application of phosphorescent iridium (III) complex systems. Adv. Mater. 21(44), 4418–4441 (2009)

    Article  CAS  Google Scholar 

  8. H. Rudmann, S. Shimada, M.F. Rubner, Solid-state light-emitting devices based on the tris-chelated ruthenium (II) complex. 4. High-efficiency light-emitting devices based on derivatives of the tris (2, 2′-bipyridyl) ruthenium (II) complex. J. Am. Chem. Soc. 124(17), 4918–4921 (2002)

    Article  CAS  Google Scholar 

  9. E.C. Constable, M. Neuburger, P. Rösel et al., Ligand-based charge-transfer luminescence in ionic cyclometalated Iridium (III) complexes bearing a pyrene-functionalized bipyridine ligand: a joint theoretical and experimental study. Inorg. chem. 52(2), 885–897 (2012)

    Article  Google Scholar 

  10. S. Graber, K. Doyle, M. Neuburger et al., A supramolecularly-caged ionic iridium (III) complex yielding bright and very stable solid-state light-emitting electrochemical cells. J. Am. Chem. Soc. 130(45), 14944–14945 (2008)

    Article  CAS  Google Scholar 

  11. R.D. Costa, E. Ortí, D. Tordera et al., Stable and efficient solid-state light-emitting electrochemical cells based on a series of hydrophobic iridium complexes. Adv. Funct. 1(2), 282–290 (2011)

    CAS  Google Scholar 

  12. S.B. Meier, D. Tordera, A. Pertegás, C. Roldán-Carmona, E. Ortí, H.J. Bolink, Light-emitting electrochemical cells: recent progress and future prospects. Mater. Today. 17(5), 217–223 (2014)

    Article  CAS  Google Scholar 

  13. R.D. Costa, E. Orti, H.J. Bolink, S. Graber, C.E. Housecroft, E.C. Constable, Intramolecular π-stacking in a phenylpyrazole-based iridium complex and its use in light-emitting electrochemical cells. J Am. Chem. Soc. 132(17), 5978–5980 (2010)

    Article  CAS  Google Scholar 

  14. H.C. Su, F.C. Fang, T.Y. Hwu et al., Highly efficient orange and green solid-state light-emitting electrochemical cells based on cationic Ir(III) complexes with enhanced steric hindrance. Adv. Funct. 17(6), 1019–1027 (2007)

    Article  CAS  Google Scholar 

  15. H.J. Bolink, E. Coronado, R.D. Costa, N.E. LardiésOrtí, Near-quantitative internal quantum efficiency in a light-emitting electrochemical cell. Inorg. chem. 47(20), 9149–9151 (2008)

    Article  CAS  Google Scholar 

  16. J.D. Slinker, A.A. Gorodetsky, M.S. Lowry et al., Efficient yellow electroluminescence from a single layer of a cyclometalated iridium complex. J. Am. Chem. Soc. 126(9), 2763–2767 (2004)

    Article  CAS  Google Scholar 

  17. H.J. Bolink, L. Cappelli, E. Coronado et al., Stable single-layer light-emitting electrochemical cell using 4,7-diphenyl-1,10-phenanthroline-bis(2-phenylpyridine)iridium(III) Hexafluorophosphate. J. Am. Chem. Soc. 128(46), 14786–14787 (2006)

    Article  CAS  Google Scholar 

  18. Gaussian09W, Version 8.0, M. [computer program]. USA: Gaussian, Inc., Wallingford CT; 2009

  19. Y. Zhao, D.G. Truhlar, The M06 suite of density functionals for main group thermochemistry, thermochemical kinetics, noncovalent interactions, excited states, and transition elements: two new functionals and systematic testing of four M06-class functionals and 12 other functionals. Theor. Chem. Acc. 120(1–3), 215–241 (2008)

    Article  CAS  Google Scholar 

  20. F. Weigend, R. Ahlrichs, Balanced basis sets of split valence, triple zeta valence and quadruple zeta valence quality for H to Rn: design and assessment of accuracy. Phys. Chem. Chem. Phys. 7(18), 3297–3305 (2005)

    Article  CAS  Google Scholar 

  21. F. Weigend, Accurate coulomb-fitting basis sets for H to Rn. Phys. Chem. Chem. Phys. 8(9), 1057–1065 (2006)

    Article  CAS  Google Scholar 

  22. M. Graf, Y. Gothe, N. Metzler-Nolte, R. Czerwieniec, K. Sünkel, Bis-cyclometalated rhodium-and iridium-complexes with the 4,4′-dichloro-2,2′-bipyridine ligand. Evaluation of their photophysical properties and biological activity. Inorg. Chim. Acta 463, 36–43 (2017)

    Article  CAS  Google Scholar 

  23. M. Graf, Y. Gothe, N. Metzler-Nolte, R. Czerwieniec, K. Sünkel, Photophysical and biological characterization of new cationic cyclometalated M (III) complexes of rhodium and iridium. J. Organomet. 765, 46–52 (2014)

    Article  CAS  Google Scholar 

  24. Y. Ohsawa, S. Sprouse, K. King, M. DeArmond, K. Hanck, R. Watts, Electrochemistry and spectroscopy of ortho-metalated complexes of iridium (III) and rhodium (III). J. Phys. Chem. 91(5), 1047–1054 (1987)

    Article  CAS  Google Scholar 

  25. D. Mochizuki, M. Sugiyama, M.M. Maitani, Y. Wada, Rigidochromic phosphorescence of [Ir (2-phenylpyridine) 2 (2, 2′-bipyridine)]+ in C16TMA+: layered silicate and its förster resonance energy transfer. Eur. J. Inorg. Chem. 2013(13), 2324–2329 (2013)

    Article  CAS  Google Scholar 

  26. M. Graf, K. Sünkel, R. Czerwieniec, H.-C. Böttcher, Luminescent diiridium (III) complex with a bridging biuretato ligand in unprecedented N, N′: O, O′ coordination. J. Organomet. 745, 341–346 (2013)

    Article  Google Scholar 

  27. P. Innocenzi, H. Kozuka, T. Yoko, Fluorescence properties of the Ru (bpy) 32+ complex incorporated in sol-gel-derived silica coating films. J. Phys. Chem. B. 101(13), 2285–2291 (1997)

    Article  CAS  Google Scholar 

  28. J.V. Caspar, T.J. Meyer, Application of the energy gap law to nonradiative, excited-state decay. J. Phys. Chem. 87(6), 952–957 (1983)

    Article  CAS  Google Scholar 

  29. T. Sajoto, P.I. Djurovich, A.B. Tamayo, J. Oxgaard, W.A. Goddard III., M.E. Thompson, Temperature dependence of blue phosphorescent cyclometalated Ir (III) complexes. J. Am. Chem. Soc. 131(28), 9813–9822 (2009)

    Article  CAS  Google Scholar 

  30. L. Yang, F. Okuda, K. Kobayashi et al., Syntheses and phosphorescent properties of blue emissive iridium complexes with tridentate pyrazolyl ligands. Inorg. Chem. 47(16), 7154–7165 (2008)

    Article  CAS  Google Scholar 

  31. R.D. Costa, F. Monti, G. Accorsi, A. Barbieri, H.J. Bolink, E. Orti, N. Armaroli, Photophysical properties of charged cyclometalated Ir (III) complexes: a joint theoretical and experimental study. Inorg. Chem. 50(15), 7229–7238 (2011)

    Article  CAS  Google Scholar 

  32. X. Zhang, D. Jacquemin, Q. Peng, Z. Shuai, D. Escudero, general approach to compute phosphorescent OLED efficiency. J. Phys. Chem. C. 122(11), 6340–6347 (2018)

    Article  CAS  Google Scholar 

  33. K. Nozaki, Theoretical studies on photophysical properties and mechanism of phosphorescence in [fac-Ir (2-phenylpyridine) 3]. J. Chin. Chem. Soc. 53(1), 101–112 (2006)

    Article  CAS  Google Scholar 

  34. H. Yersin, J. Strasser, Triplets in metal–organic compounds Chemical tunability of relaxation dynamics. Coord. Chem. Rev. 208(1), 331–364 (2000)

    Article  CAS  Google Scholar 

  35. C.D. Ertl, L. Gil-Escrig, J. Cerdá, Regioisomerism in cationic sulfonyl-substituted [Ir (C^ N) 2 (N^ N)]+ complexes: its influence on photophysical properties and LEC performance. Dalton Trans. 45(29), 11668–11681 (2016)

    Article  CAS  Google Scholar 

  36. T. Azumi, C.M. O’Donnell, S.P. McGlynn, On the multiplicity of the state of organic molecules. J. Chem. Phys. 45(8), 2735–2742 (1966)

    Article  CAS  Google Scholar 

  37. W.J. Finkenzeller, H. Yersin, Emission of Ir (ppy) 3. Temperature dependence, decay dynamics, and magnetic field properties. Chem. Phys. Lett. 377(3–4), 299–305 (2003)

    Article  CAS  Google Scholar 

  38. S. Arroliga-Rocha, D. Escudero, Facial and meridional isomers of Tris(bidentate) Ir(III) complexes: unravelling their different excited state reactivity. Inorg. Chem. 57(19), 12106–12112 (2018)

    Article  CAS  Google Scholar 

  39. D. Escudero, E. Heuser, R.J. Meier, M. Schäferling, W. Thiel, E. Holder, Unveiling photodeactivation pathways for a new Iridium(III) cyclometalated complex. Chem. Eur. J. 19(46), 15639–15644 (2013)

    Article  CAS  Google Scholar 

  40. D. Escudero, Quantitative prediction of photoluminescence quantum yields of phosphors from first principles. Chem. Eng. Sci. 7(2), 1262–1267 (2016)

    CAS  Google Scholar 

Download references

Acknowledgements

We would like to thanks for the support of ISEF. MJ also gratefully acknowledges Prof. Hartmut Yersin, Dr. Rafał Czerwieniec, Marsel Z. Shafikov, and Alexander Schinabeck for providing facilities and helpful guidance during her visiting at Regensburg University. She also thanks Prof. Marion Graf for providing the compounds.

Author information

Authors and Affiliations

  1. Department of Chemistry, College of Sciences, Shiraz University, Shiraz, 71467-13565, Iran

    Mahboubeh Jamshidi & S. Masoud Nabavizadeh

  2. Institute of Physical and Theoretical Chemistry, University of Regensburg, 93053, Regensburg, Germany

    Mahboubeh Jamshidi

Authors
  1. Mahboubeh Jamshidi
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. S. Masoud Nabavizadeh
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Mahboubeh Jamshidi.

Supplementary Information

Below is the link to the electronic supplementary material.

Supplementary file1 (DOCX 57 KB)

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Jamshidi, M., Nabavizadeh, S.M. Comprehensive investigation of triplet states of red phosphorescent cationic Ir(III) complexes from cryogenic temperature. J IRAN CHEM SOC 20, 451–458 (2023). https://doi.org/10.1007/s13738-022-02680-y

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s13738-022-02680-y

Keywords

Search

Navigation