Towards Water Soluble Mitochondria-Targeting Theranostic Osmium(II) Triazole-Based Complexes
Open Access
Abstract
The complex [Os(btzpy)2][PF6]2 (1, btzpy = 2,6-bis(1-phenyl-1,2,3-triazol-4-yl)pyridine) has been prepared and characterised. Complex 1 exhibits phosphorescence (λem = 595 nm, τ = 937 ns, φem = 9.3% in degassed acetonitrile) in contrast to its known ruthenium(II) analogue, which is non-emissive at room temperature. The complex undergoes significant oxygen-dependent quenching of emission with a 43-fold reduction in luminescence intensity between degassed and aerated acetonitrile solutions, indicating its potential to act as a singlet oxygen sensitiser. Complex 1 underwent counterion metathesis to yield [Os(btzpy)2]Cl2 (1Cl), which shows near identical optical absorption and emission spectra to those of 1. Direct measurement of the yield of singlet oxygen sensitised by 1Cl was carried out (φ (1O2) = 57%) for air equilibrated acetonitrile solutions. On the basis of these photophysical properties, preliminary cellular uptake and luminescence microscopy imaging studies were conducted. Complex 1Cl readily entered the cancer cell lines HeLa and U2OS with mitochondrial staining seen and intense emission allowing for imaging at concentrations as low as 1 μM. Long-term toxicity results indicate low toxicity in HeLa cells with LD50 >100 μM. Osmium(II) complexes based on 1 therefore present an excellent platform for the development of novel theranostic agents for anticancer activity.Keywords
Funding Information
- Wellcome Trust (WT093134AIA)
- MRC SHIMA (MR/K015753/1)
- EPRSC (EP/L000202)
This publication has 56 references indexed in Scilit:
- Luminescent biscyclometalated arylpyridine iridium(iii) complexes with 4,4′-bi-1,2,3-triazolyl ancillary ligandsDalton Transactions, 2013
- Monometallic Osmium(II) Complexes with Bis(N-methylbenzimidazolyl)benzene or -pyridine: A Comparison Study with Ruthenium(II) AnaloguesInorganic Chemistry, 2013
- Recent advances in light-emitting electrochemical cellsPure and Applied Chemistry, 2011
- Enhanced Luminescent Iridium(III) Complexes Bearing Aryltriazole Cyclometallated LigandsInorganic Chemistry, 2011
- Synthesis and characterisation of luminescent rhenium tricarbonyl complexes with axially coordinated 1,2,3-triazole ligandsDalton Transactions, 2011
- NWChem: A comprehensive and scalable open-source solution for large scale molecular simulationsComputer Physics Communications, 2010
- Reevaluation of absolute luminescence quantum yields of standard solutions using a spectrometer with an integrating sphere and a back-thinned CCD detectorPhysical Chemistry Chemical Physics, 2009
- Consequences ofN,C,N′- andC,N,N′-Coordination Modes on Electronic and Photophysical Properties of Cyclometalated Aryl Ruthenium(II) ComplexesInorganic Chemistry, 2009
- Pendant-functionalised ligands for metallosupramolecular assemblies; ruthenium(II) and osmium(II) complexes of 4′-(4-pyridy1)-2,2′ : 6′,2″-terpyridineJ. Chem. Soc., Dalton Trans., 1994
- Energy-adjustedab initio pseudopotentials for the second and third row transition elementsTheoretical Chemistry Accounts, 1990