Photooxidation of nickel(II) macrocyclic complexes by mono- and biphotonicprocesses from the charge-transfer to solvent excited states in aqueous solutions

Excitation of nickel(II) macrocyclic complexes using 248 nm laser pulses le ads to the formation of solvated electron in aqueous solutions. Formation o f solvated electrons is confirmed by a characteristic absorption spectrum w hich shows a maximum at 680 nm. From the decay kinetics, bimolecular rate c onstants were determined for the decay of the solvated electron. Nickel(II) complexes with saturated macrocyclic ligands produce photoelectrons by bip hotonic processes and the nickel(II) complex with unsaturated ligand ejects electrons from excited states by a monophotonic process as determined by v arying the excitation energy of the laser. (C) 2000 Elsevier Science B.V. A ll rights reserved.