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Tuning the Optical Properties of 2‐Thienylpyridyl Iridium Complexes through Carboranes and Anions
Author(s) -
Zhu Lin,
Tang Xiao,
Yu Qi,
Lv Wen,
Yan Hong,
Zhao Qiang,
Huang Wei
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201405897
Subject(s) - phosphorescence , iridium , chemistry , hydrogen bond , carborane , ion , ligand (biochemistry) , titration , crystallography , hydrogen , photochemistry , inorganic chemistry , molecule , medicinal chemistry , catalysis , fluorescence , organic chemistry , biochemistry , physics , receptor , quantum mechanics
Abstract 2‐Thienylpyridyl iridium(III) complexes containing an o ‐, m ‐, or p ‐carboranylvinyl‐2,2′‐bipyridine ligand and various counteranions (denoted o ‐ PF 6 , m ‐ BF 4 , m ‐ PF 6 , m ‐ SbF 6 , m ‐ ClO 4 , m ‐ OTf , m ‐ NO 3 , m ‐ BPh 4 , m ‐ F , m ‐ Cl , and p ‐ PF 6 ) were synthesized by using C ‐formyl carboranes as starting materials. The solid‐state structures of o ‐ PF 6 , m ‐ PF 6 , m ‐ ClO 4 , and m ‐ BF 4 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 CH ⋅⋅⋅ X anion–hydrogen bonds strongly influence the phosphorescence quantum yield in the solid state. In particular, the C car H ⋅⋅⋅ X hydrogen bonds between the carboranyl unit and the anion play an important role in solid‐state phosphorescence. Complex p ‐ PF 6 was successfully applied in phosphorescence‐lifetime bioimaging owing to its low toxicity and near‐infrared emission.