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Besides their superior photophysical properties, phosphorescent transition-metal complexes have some drawbacks for biological applications because of their poor solubility in aqueous solutions and toxicity. In order to avoid the biological environmental impacts on their optical function and solve the problems of water-solubility and toxicity in sensing and bioimaging, two biocompatible organic/inorganic hybrid phosphorescent nanoprobes (Ir-MSN) by using mesoporous silica nanoparticles (MSN) as carriers and an iridium(III) complex as signaling unit were prepared in the present study. In addition, folic acid (FA) was covalently attached to them to endow the particles with characteristic of tumor targeting. The photophysical properties, cell staining and tumor cell targeting functions of FA-ligated Ir-MSN were investigated. These results demonstrated that such a design strategy of phosphorescent nanoprobes is an effective way to develop excellent phosphorescent cellular probes for living cell applications.

Organelle-targeted photosensitizers have been reported to be effective photodynamic therapy (PDT) agents. In this work, we designed and synthesized two iridium(III) complexes that specifically stain the mitochondria and lysosomes of living cells, respectively. Both complexes exhibited long-lived phosphorescence, which is sensitive to oxygen quenching. The photocytotoxicity of the complexes was evaluated under normoxic and hypoxic conditions. The results showed that HeLa cells treated with the mitochondria-targeted complex maintained a slower respiration rate, leading to a higher intracellular oxygen level under hypoxia. As a result, this complex exhibited an improved PDT effect compared to the lysosome-targeted complex, especially under hypoxia conditions, suggestive of a higher practicable potential of mitochondria-targeted PDT agents in cancer therapy., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Organelle-targeted photosensitizers have been reported to be effective photodynamic therapy (PDT) agents. In this work, we designed and synthesized two iridium(III) complexes that specifically stain the mitochondria and lysosomes of living cells, respectively. Both complexes exhibited long-lived phosphorescence, which is sensitive to oxygen quenching. The photocytotoxicity of the complexes was evaluated under normoxic and hypoxic conditions. The results showed that HeLa cells treated with the mitochondria-targeted complex maintained a slower respiration rate, leading to a higher intracellular oxygen level under hypoxia. As a result, this complex exhibited an improved PDT effect compared to the lysosome-targeted complex, especially under hypoxia conditions, suggestive of a higher practicable potential of mitochondria-targeted PDT agents in cancer therapy. [ABSTRACT FROM AUTHOR]

2-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. [ABSTRACT FROM AUTHOR]

Phosphorescent iridium(III) complexes with three bidentate carborane‐functionalized ligands have been synthesized. The luminescent efficiency of the o‐carborane‐based facial complex fac‐o shows solvent‐molecule dependence both in solution and solid state that is related to the dielectric constant. The water‐soluble and high phosphorescence‐efficient nido complex nido‐fac‐o can be used in fluorescence lifetime bioimaging. [ABSTRACT FROM AUTHOR]

• A series of iridium(III) solvato complexes with good water solubility are designed and synthesized. • They can be used for multicolor cytoplasm imaging of living cells. • Two-photon excited imaging and fluorescence lifetime imaging microscopy have been achieved. Fluorescence microscopy imaging provides an indispensable way to visualize morphological details in tissue with subcellular resolution. Of the various imaging agents currently available, heavy-metal complex based probes offer a powerful tool for live cell imaging, primarily due to their excellent photophysical properties, including evident Stokes shifts, high photoluminescence efficiency and relatively long emission lifetime of phosphorescent signals. Herein, we have designed and synthesized seven water soluble cationic iridium(III) solvato complexes (1 − 7) for live cell imaging. The emission colors of these iridium(III) complexes can be tuned from green to red in PBS buffer (phosphate buffered saline). In particular, multicolor phosphorescent imaging for cytoplasm staining of living cells has been realized. More importantly, two-photon excited imaging and fluorescence lifetime imaging microscopy have also successfully been applied for complex 7. [Display omitted] A series of iridium(III) solvato complexes (1 − 7) with good water solubility have been designed and synthesized for multicolor cytoplasm imaging of living cells. Furthermore, two-photon excited imaging and fluorescence lifetime imaging microscopy have also been achieved. [ABSTRACT FROM AUTHOR]