Unconventional thermodynamically stable cis isomer and trans to cis thermal isomerization in reversibly photoresponsive [0.0](3,3′)-azobenzenophane

Sterically hindered [ 0.0]( 3,3')-azobenzenophane exhibits thermal trans-to-cis isomerization to the thermodynamically stable cis-cis isomer, and reversible photochemical isomerization with good fatigue resistance.