Donor-Acceptor Viologens with Through-Space Conjugation for Enhanced Visible-Light-Driven Photocatalysis.

A series of novel donor-acceptor (D-A) type viologens with through-space conjugation (TSC) are synthesized. The synergistic effect of D-A conjugation and TSC endow these compounds with a narrower energy gap, excellent redox properties, strong absorption in the visible range (up to 450 nm), and high efficiency of intramolecular charge transfer (ICT). These compounds also exhibit a long-lived charge separation state and stable radical formation.

Directional Electron Flow in a Selenoviologen-Based Tetracationic Cyclophane for Enhanced Visible-Light-Driven Hydrogen Evolution.

Directional electron flow in the photocatalyst enables efficient charge separation, which is essential for efficient photocatalysis of H production. Here, we report a novel class of tetracationic cyclophanes (7) incorporating bipyridine Pt(II) and selenoviologen. X-ray single-crystal structures reveal that 7 not only fixes the distances and spatial positions between its individual units but also exhibits a box-like rigid electron-deficient cavity.

The Green Box: Selenoviologen-Based Tetracationic Cyclophane for Electrochromism, Host-Guest Interactions, and Visible-Light Photocatalysis.

The novel selenoviologen-based tetracationic cyclophanes (green boxes and ) with rigid electron-deficient cavities are synthesized via S2 reactions in two steps. The green boxes exhibit good redox properties, narrow energy gaps, and strong absorption in the visible range (370-470 nm), especially for the green box containing two selenoviologen (SeV) units. Meanwhile, the femtosecond transient absorption (fs-TA) reveals that the green boxes have a stabilized dicationic biradical, high efficiency of intramolecular charge transfer (ICT), and long-lived charge separation state due to the formation of cyclophane structure.