Tailoring the Emission of Fluorinated Bipyridine-Chelated Iridium Complexes

Overview

Journal ACS Omega

Publisher American Chemical Society

Specialty Chemistry

Date 2019 Aug 29

PMID 31458080

Authors

Guang Zhang

Martin Baumgarten

Dieter Schollmeyer

Klaus Mullen

Affiliations

Soon will be listed here.

Abstract

New functionalized tris(2',6'-difluoro-2,3'-bipyridinato-,C4')iridium(III) ((dfpypy)Irs) complexes, including small molecules and their dendrimer embedded analogoues, were synthesized and characterized. It is demonstrated that both the -(dfpypy)Ir-based polyphenylene dendrimers and (triisopropylsilyl)ethynyl (TIPSE)-substituted (dfpypy)Ir complexes induce large bathochromic shifts (∼50 nm) of emission bands compared with -(dfpypy)Ir. This is due to the pronounced π-π* character of emissive excited states and the extended conjugation. A further remarkable feature is the small bathochromic shift of the emissions of -tris(2-phenylpyridine)iridium (-(ppy)Ir)-based polyphenylene dendrimers when compared to those of the iridium (Ir) complex core. Obviously, the triplet metal-to-ligand charge transfer makes emission less sensitive to extended conjugation than the π-π* transition. This finding suggests new concepts for designing blue phosphorescent dendrimer emitters. Both the dendrimers and the TIPSE-substituted (dfpypy)Ir complexes represent new green and the trimethylsilyl-functionalized (dfpypy)Ir new blue phosphorescent emitters. Incorporation of TIPSE moieties into the ligands of iridium complex gives rise to enhanced phosphorescence.

References

Wang P, Zakeeruddin S, Moser J, Nazeeruddin M, Sekiguchi T, Gratzel M . A stable quasi-solid-state dye-sensitized solar cell with an amphiphilic ruthenium sensitizer and polymer gel electrolyte. Nat Mater. 2003; 2(6):402-7. DOI: 10.1038/nmat904. View

Tamayo A, Alleyne B, Djurovich P, Lamansky S, Tsyba I, Ho N . Synthesis and characterization of facial and meridional tris-cyclometalated iridium(III) complexes. J Am Chem Soc. 2003; 125(24):7377-87. DOI: 10.1021/ja034537z. View

Lu W, Mi B, Chan M, Hui Z, Che C, Zhu N . Light-emitting tridentate cyclometalated platinum(II) complexes containing sigma-alkynyl auxiliaries: tuning of photo- and electrophosphorescence. J Am Chem Soc. 2004; 126(15):4958-71. DOI: 10.1021/ja0317776. View

DeRosa M, Hodgson D, Enright G, Dawson B, Evans C, Crutchley R . Iridium luminophore complexes for unimolecular oxygen sensors. J Am Chem Soc. 2004; 126(24):7619-26. DOI: 10.1021/ja049872h. View

Sajoto T, Djurovich P, Tamayo A, Yousufuddin M, Bau R, Thompson M . Blue and near-UV phosphorescence from iridium complexes with cyclometalated pyrazolyl or N-heterocyclic carbene ligands. Inorg Chem. 2005; 44(22):7992-8003. DOI: 10.1021/ic051296i. View

Kawamura Y, Brooks J, Brown J, Sasabe H, Adachi C . Intermolecular interaction and a concentration-quenching mechanism of phosphorescent Ir(III) complexes in a solid film. Phys Rev Lett. 2006; 96(1):017404. DOI: 10.1103/PhysRevLett.96.017404. View

Wu F, Shih P, Tseng Y, Chen G, Chien C, Shu C . Highly efficient red-electrophosphorescent devices based on polyfluorene copolymers containing charge-transporting pendant units. J Phys Chem B. 2006; 109(29):14000-5. DOI: 10.1021/jp051747k. View

Zhou G, Wong W, Yao B, Xie Z, Wang L . Triphenylamine-dendronized pure red iridium phosphors with superior OLED efficiency/color purity trade-offs. Angew Chem Int Ed Engl. 2007; 46(7):1149-51. DOI: 10.1002/anie.200604094. View

Lo S, Burn P . Development of dendrimers: macromolecules for use in organic light-emitting diodes and solar cells. Chem Rev. 2007; 107(4):1097-116. DOI: 10.1021/cr050136l. View

10.

Lai C, Wang Y, Lai C, Yang M, Chen C, Chou P . Iridium-complex-functionalized Fe3O4/SiO2 core/shell nanoparticles: a facile three-in-one system in magnetic resonance imaging, luminescence imaging, and photodynamic therapy. Small. 2008; 4(2):218-24. DOI: 10.1002/smll.200700283. View

11.

McDonald A, Lutz M, von Chrzanowski L, van Klink G, Spek A, van Koten G . Probing the mer- to fac-isomerization of tris-cyclometallated homo- and heteroleptic (C,N)3 iridium(III) complexes. Inorg Chem. 2008; 47(15):6681-91. DOI: 10.1021/ic800169n. View

12.

Qin T, Zhou G, Scheiber H, Bauer R, Baumgarten M, Anson C . Polytriphenylene dendrimers: a unique design for blue-light-emitting materials. Angew Chem Int Ed Engl. 2008; 47(43):8292-6. DOI: 10.1002/anie.200802854. View

13.

Hwang S, Moorefield C, Newkome G . Dendritic macromolecules for organic light-emitting diodes. Chem Soc Rev. 2008; 37(11):2543-57. DOI: 10.1039/b803932c. View

14.

Lee S, Park K, Yang K, Kang Y . Blue phosphorescent Ir(III) complex with high color purity: fac-tris(2',6'-difluoro-2,3'-bipyridinato-N,C(4'))iridium(III). Inorg Chem. 2009; 48(3):1030-7. DOI: 10.1021/ic801643p. View

15.

Sajoto T, Djurovich P, Tamayo A, Oxgaard J, Goddard 3rd W, Thompson M . Temperature dependence of blue phosphorescent cyclometalated Ir(III) complexes. J Am Chem Soc. 2009; 131(28):9813-22. DOI: 10.1021/ja903317w. View

16.

Qin T, Ding J, Wang L, Baumgarten M, Zhou G, Mullen K . A divergent synthesis of very large polyphenylene dendrimers with iridium(III) cores: molecular size effect on the performance of phosphorescent organic light-emitting diodes. J Am Chem Soc. 2009; 131(40):14329-36. DOI: 10.1021/ja905118t. View

17.

Lo S, Harding R, Shipley C, Stevenson S, Burn P, Samuel I . High-triplet-energy dendrons: enhancing the luminescence of deep blue phosphorescent iridium(III) complexes. J Am Chem Soc. 2009; 131(46):16681-8. DOI: 10.1021/ja903157e. View

18.

Xiao L, Chen Z, Qu B, Luo J, Kong S, Gong Q . Recent progresses on materials for electrophosphorescent organic light-emitting devices. Adv Mater. 2010; 23(8):926-52. DOI: 10.1002/adma.201003128. View

19.

Qin T, Wiedemair W, Nau S, Trattnig R, Sax S, Winkler S . Core, shell, and surface-optimized dendrimers for blue light-emitting diodes. J Am Chem Soc. 2011; 133(5):1301-3. DOI: 10.1021/ja109734e. View

20.

Jeon S, Jang S, Son H, Lee J . External quantum efficiency above 20% in deep blue phosphorescent organic light-emitting diodes. Adv Mater. 2011; 23(12):1436-41. DOI: 10.1002/adma.201004372. View