Though the properties of N-heterocyclic carbenes (NHCs) are generally dominated by the very strong σ donating character, electronic activation has emerged as an effective method to cooperate with typical carbon-framework steric optimization for highly enantioselective chiral NHC–transition-metal catalysis in recent years. NHC electronic changes associated with structural variations are now better understood by quantitative analysis using various methods. Here we highlighted and correlated some interesting chiral induction improvement methods, which were brought by electronic and steric cooperation on chiral NHC–transition-metal catalysis.1 Introduction2 Hemilabile Sidechains on NHC Ligands3 Electronic and Bond Angle Changes Brought by NHC Core Size Variations4 Electronic Activators on the NHC Core5 Conjugated Systems and Fused Ring Structures6 Remote Electronic Activators on the N-Aryl Ring7 Summary and Outlook

Strategies enabling the pH-dependent conformational switching of amide bonds from trans to cis, and vice versa, are yet limited in the sense that, in a suitable pH range, one rotamer may be stabilized to a large extent while the complementary pH range only leads to a mixture of isomers. By exploiting the effects of steric demand and the interaction of the amide carbonyl with a positive charge, we herein present the first examples for reversible pH-dependent switching from full trans to full cis.

Optical storage and photon quantification systems based on sensitive photoreactions have numerous applications. Herein, we report a highly efficient photocatalytic reaction, in which ruthenium photoredox catalysis is combined with a 1,2-dioxetane from which chemiluminescence can be triggered. In this system, blue light irradiation as optical input enables a defined inverse correlation with base-triggered, blue light emission as optical output. Comparison of readout by 1 H NMR and chemiluminescence, relative to previous optical input, underlines the reliability and usefulness of the ruthenium-dioxetane system for optical storage, sensing and ruthenium detection.

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Systeme zur optischen Speicherung und zur Quantifizierung von Photonen, welche auf sensitiven Photoreaktionen basieren, haben zahlreiche Anwendungen. In dieser Arbeit berichten wir von einer hocheffizienten photokatalysierten Reaktion, in der die Photoredoxkatalyse über einen Rutheniumkatalysator mit einem 1,2‐Dioxetan kombiniert wird, von dem aus Chemilumineszenz ausgelöst werden kann. Die Bestrahlung mit blauem Licht, die als optische Eingabe dient, korreliert in diesem System definiert mit der basen‐induzierten Emission blauen Lichts. Vergleiche des Auslesens mittels 1H NMR und Chemilumineszenz, jeweils in Abhängigkeit der vorherigen Bestrahlung, unterstreichen die Zuverlässigkeit und Anwendbarkeit des Ruthenium‐Dioxetan‐Systems für optische Datenspeicherung, optische Messungen und die Detektion von Photokatalysatoren.