A 7.4% power conversion efficiency at air mass (AM) 1.5 full sunlight was reached with a mesoscopic solar cell employing a new binary ionic liquid electrolyte composed of 1-propyl-3-methylimidazolium iodide and 1-ethyl-3-methylimidazolium tricyanomethanide in conjunction with the amphiphilic ruthenium complex NaRu(4-carboxylic acid-4'-carboxylate)(4,4'-dinonyl-2,2'-bipyridine)(NCS)(2), coded as Z-907Na. Ultramicroelectrode voltammetric, nanosecond laser transient absorbance, and photovoltaic measurements show that a high iodide concentration is required for dye regeneration to compete efficiently with charge recombination. A surprisingly fast reductive quenching process is turned on in pure iodide melts. This channel is unproductive, explaining the lower photocurrents observed under these conditions.

N,N,N′,N′‐(Tetramethyl)thioharnstoff (1) reagiert mit N,N‐Dimethylcarbamoylchlorid (2) zu dem Guanidiniumsalz 3a. Dimethylsulfat setzt sich mit 1 zum Salz 4 um, das mit Dimethylamin in 3b übergeführt wird. Chlorformamidiniumsalze 5, erhalten aus N,N,N′,N′‐(Tetraalkylharnstoffen und Phosgen, reagieren mit Gemischen aus sekundären oder primären und tertiären Aminen zu Gemischen aus Guanidinium‐ und Ammoniumsalzen. Daraus lassen sich die Guanidiniumsalze 3a, 6 bzw. 11 gewinnen. Die Salze 3a und 6 werden in Tetraphenylborate 7 umgewandelt. Aus den Guanidiniumchloriden 3a und 6h werden die Fluoroborate 8a bzw. 8b hergestellt. Durch Anionenaustausch werden aus 8a, b die Salze 9, 10 dargestellt. Aus den Guanidinen 12 werden die Salze 13 gewonnen.

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1H, 2H, and 11B NMR spectroscopy has been used to study the mechanism of the Fries rearrangement of aryl formates promoted by boron trichloride by monitoring both the substrate and the Lewis acid. DFT calculations were employed to investigate the energetics of several reaction paths and to calculate NMR chemical shifts of key intermediates and products. After the formation of a 1:1 substrate−Lewis acid adduct, the rearrangement proceeds in two steps, beginning with the cleavage of the ester bond and the release of formyl chloride in situ, which, in turn, acts as a formylating agent, introducing an aldehydic functionality into the aromatic ring. The high regioselectivity (only the ortho product is obtained) is also accounted for by the proposed intermolecular, Lewis acid-assisted mechanism.