Photochemistry of 1,2-bis(heteroaryl)ethylenes: photoisomerization of 1-pyrazinyl-2-(4-quinolinyl)ethylene

Abstract

The direct and sensitized photoisomerization of 1-pyrazinyl-2-(4-quinolyl)ethylene (4-PyQE) has been investigated under various conditions. Azulene quenches the direct and triplet-sensitized E→Z photoisomerization very efficiently. Azulene quenching and direct and sensitized E→Z photoisomerization studies indicate an efficient intersystem crossing on direct excitation of (E)-4-PyQE and direct E→Z photoisomerization proceeds through a triplet excited state.