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

Excitation of nickel(II) macrocyclic complexes using 248 nm laser pulses leads to the formation of solvated electron in aqueous solutions. Formation of solvated electrons is confirmed by a characteristic absorption spectrum which shows a maximum at 680 nm. From the decay kinetics, bimolecular rate constants were determined for the decay of the solvated electron. Nickel(II) complexes with saturated macrocyclic ligands produce photoelectrons by biphotonic processes and the nickel(II) complex with unsaturated ligand ejects electrons from excited states by a monophotonic process as determined by varying the excitation energy of the laser.