Synthesis and (spectro)electrochemical investigations of coordinatively-saturated (cyclopentadienyl)ruthenium–Hantzsch pyridinium/dihydropyridine conjugates

Connecting Ruthenium Photocatalysis to 1,2-Dioxetane-Mediated Chemiluminescence: a Versatile Combination for Optical Detection and Read-Out

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.

Thermodynamic Parameters of Elementary Steps for 3,5-Disubstituted 1,4-Dihydropyridines To Release Hydride Anions in Acetonitrile

A series of 3,5-disubstituted 1,4-dihydropyridine derivatives including the derivative with two chiral centers, 6H (R² = CH₃, CH₂Ph), as a new type of organic hydride source were synthesized and characterized. The thermodynamic driving forces (defined as enthalpy changes or standard redox potentials) of the 6 elementary steps for the organic hydrides to release hydride ions in acetonitrile were measured by isothermal titration calorimetry and electrochemical methods. The impacts of the substituents and functional groups bearing the N1 and C3/C5 positions on the thermodynamic driving forces of the 6 elementary steps were examined and analyzed. Moreover, the results showed that the reaction mechanism between the chiral organic hydride and activated ketone (ethyl benzoylformate) was identified as the concerted hydride transfer pathway based on the thermodynamic analysis platform. These valuable and crucial thermodynamic parameters will provide a broadly beneficial impact on the applications of 3,5-disubstituted 1,4-dihydropyridine derivatives in organic synthesis and pharmaceutical chemistry.