Electrochemical gating at the single molecule level of viologen molecular bridges in ionic liquids is examined. Contrary to previous data recorded in aqueous electrolytes, a clear and sharp peak in the single molecule conductance versus electrochemical potential data is obtained in ionic liquids. These data are rationalized in terms of a two-step electrochemical model for charge transport across the redox bridge. In this model the gate coupling in the ionic liquid is found to be fully effective with a modeled gate coupling parameter, ξ, of unity. This compares to a much lower gate coupling parameter of 0.2 for the equivalent aqueous gating system. This study shows that ionic liquids are far more effective media for gating the conductance of single molecules than either solid-state three-terminal platforms created using nanolithography, or aqueous media.

Zum Ende des Sommers nimmt die Zahl der Insekten in Wald und Flur deutlich ab. Nur noch wenige Schmetterlinge gaukeln über blütenarme Wiesen. Doch einige häufige Nachtfalter‐Raupen sind gerade im September und Oktober kaum zu übersehen und ermöglichen somit interessante Beobachtungen im Herbst.

The 2e reduced anion [Mn(CO) 3 (iPr-DAB)] − (DAB = 1,4diazabuta-1,3-diene, iPr = isopropyl) was shown to convert in the presence of CO 2 and a small amount of water to the unstable complex [Mn(CO) 3 (iPr-DAB)(η 1 -OCO 2 H)] (OCO 2 H − = unidentate bicarbonate) that was further reductively transformed to give a stable catalytic intermediate denoted as X2, showing ν s (OCO) 1672 and 1646 (sh) cm −1 . The subsequent cathodic shift by ca. 650 mV in comparison to the single 2e cathodic wave of the parent [Mn(CO) 3 (iPr-DAB)Br] triggers the reduction of intermediate X2 and catalytic activity converting CO 2 to CO. Infrared spectroelectrochemistry has revealed that the high excess of CO generated at the cathode leads to the conversion of [Mn(CO) 3 (iPr-DAB)] − to inactive [Mn(CO) 5 ] − . In contrast, the five-coordinate anion [Mn(CO) 3 (pTol-DAB)] − (pTol = 4-tolyl) is completely inert toward both CO 2 and H 2 O (solvolysis). This detailed spectroelectrochemical study is a further contribution to the development of sustainable electro-and photoelectrocatalysts of CO 2 reduction based on abundant first-row transition metals, in particular manganese.

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