We also noticed that the reversible ring-opening process of 1b to 1a is sensitive to temperature during the optimization of reaction conditions. As expected, higher reaction temperatures accelerate the process, but applying longer reaction times at high temperatures leads to coformation of another product (Figure , dihydronapthalene 1d, vide infra). For this reason, we employed heating at 110°C for 10 h as the standard reaction conditions to ensure high switching efficiency for further investigations.