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Dye-sensitized solar cells (DSCs) are an attractive renewable energy technology currently under intense investigation. In recent years, one area of major interest has been the exploration of alternatives to the classical iodide/triiodide redox shuttle, with particular attention focused on cobalt complexes with the general formula [Co(L)(n)](2+/3+). We introduce a new approach to designing redox mediators that involves the application of [Co(PY5Me(2))(MeCN)](2+/3+) complexes, where PY5Me(2) is the pentadentate ligand, 2,6-bis(1,1-bis(2-pyridyl)ethyl)pyridine. It is shown, by X-ray crystallography, that the axial acetonitrile (MeCN) ligand can be replaced by more strongly coordinating Lewis bases (B) to give complexes with the general formula [Co(PY5Me(2))(B)](2+/3+), where B = 4-tert-butylpyridine (tBP) or N-methylbenzimidazole (NMBI). These commonly applied DSC electrolyte components are used for the first time to fine-tune the potential of the redox couple to the requirements of the dye through coordinative interactions with the Co(II/III) centers. Application of electrolytes based on the [Co(PY5Me(2))(NMBI)](2+/3+) complex in combination with a commercially available organic sensitizer has enabled us to attain DSC efficiencies of 8.4% and 9.2% at a simulated light intensity of 100% sun (1000 W m(-2) AM1.5 G) and at 10% sun, respectively, higher than analogous devices applying the [Co(bpy)(3)](2+/3+) redox couple, and an open circuit voltage (V(oc)) of almost 1.0 V at 100% sun for devices constructed with the tBP complex.

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In western Canada growing demand for water resources has increased vulnerability to hydrological drought. The near full allocation of water supplies in the Oldman and Bow River subbasins of the South Saskatchewan River Basin has resulted in a moratorium on new surface water licenses. In this region, short instrumental records limit the detection of long‐term hydrological variability. To extend the historical record, we collected 14 new moisture‐sensitive tree ring chronologies and reconstructed the average October through September flow of the Oldman (1618–2004) and South Saskatchewan (SSR) (1400–2004) rivers. Our SSR proxy record updates a previously published reconstruction. While the 20th century is representative of drought frequency over the long term, droughts are of greater severity and duration in the preinstrumental proxy record. A spectral analysis of the reconstructed flows revealed quasiperiodic cycles at interannual to multidecadal scales.