Fig. 1: Schematic of the QC ⇄ NBD interconversion.
From: Ultrafast electronic relaxation pathways of the molecular photoswitch quadricyclane
The isomerization reaction breaks (or forms) the 1–2 and 3–4 carbon–carbon bonds in QC, with the energy of the QC ground state located ~1 eV above the ground state of NBD. The interconversion can be driven by light absorption, allowing the system to act as a molecular photoswitch.
