Photochemistry of N,N '-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminocyclohexane and its Co(II) complex in chloroform

N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminocyclohexane (H2E) is pho tochromic. In CHCl3 it undergoes a phototautomerization (phi = 3 x 10(-4) a t lambda (irr) = 333 nm) to its keto isomer H(2)Q which is thermally reconv erted to the original enol form. The enol is not luminescent but the keto i somer shows a green fluorescence at lambda (max) = 505 nm with phi = 10(-2) at lambda (exc) = 410 nm. Accordingly, the photoreversible system does not only display a conventional photochromism but also a luminescence photochr omism. The complex Co-II(E) in CHCl3 is also light sensitive. It is irrever sibly photooxidized to Co(E)(+) with phi = 5 x 10(-3) at lambda (irr)=435 n m. The electron is not removed from the metal but from the ligand. (C) 2001 Elsevier Science B.V. All rights reserved.