Tuning the optical properties of 2-Thienylpyridyl iridium complexes through carboranes and anions

Lin Zhu, Xiao Tang, Qi Yu, Wen Lv, Hong Yan, Qiang Zhao, Wei Huang

Research output: Contribution to journalArticlepeer-review

36 Scopus citations

Abstract

Thienylpyridyl iridium(III) complexes containing an o-, m-, or p-carboranylvinyl-2,2′-bipyridine ligand and various counteranions (denoted o-PF6, m-BF4, m-PF6 m- SbF6, m-ClO4, m- OTf, m-NO3, m-BPh4, m-F, m-Cl, and p-PF6) were synthesized by using C-formyl carboranes as starting materials. The solid-state structures of o-PF6, m- PF6, m-ClO4, and m-BF4 showed that the cations form twisted cavities in which the anions are fixed by multiple hydrogen bonds. Anion-hydrogen interactions were investigated for nine m-carborane-based complexes with different counteranions. All carborane-based iridium(III) complexes show similar phosphorescence yields in solution but significantly different emission in the solid state. Anion-exchange titration and theoretical calculations revealed the relationships between structures and optical properties. The size of the anion and C-H••• X anion-hydrogen bonds strongly influence the phosphorescence quantum yield in the solid state. In particular, the Ccar-H •••X hydrogen bonds between the carboranyl unit and the anion play an important role in solid-state phosphorescence. Complex p -PF6 was successfully applied in phosphorescence-lifetime bioimaging owing to its low toxicity and near-infrared emission.

Original languageEnglish
Pages (from-to)4721-4730
Number of pages10
JournalChemistry - A European Journal
Volume21
Issue number12
DOIs
StatePublished - 16 Mar 2015
Externally publishedYes

Keywords

  • Carboranes
  • Chelates
  • Imaging agents
  • Iridium
  • Phosphorescence

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