PHOTOCHEMICAL ISOMERIZATION AROUND THE C=N DOUBLE-BONDS OF N-METHOXY-1-(1-PYRENYL)METHANIMINE IN THE EXCITED-STATE

N-Methoxy-1-(1-pyrenyl) methanimine (VII) undergoes mutual isomerizati on between the Z and E isomers around the C=N double bond on triplet s ensitization. The quantum yields of Z --> E isomerization increase lin early with the initial Z isomer concentration exceeding unity. Further more, a considerably long-lived triplet state assigned to the E triple t is observed on laser photolysis. On the basis of these experimental findings, the mechanism of isomerization of VII, proceeding by a dual two-way and one-way mode, is discussed.