LIGAND-FIELD PHOTOCHEMISTRY OF THE [CU-II(BPY)(SERINE-H)](-DOT) COMPLEX IN THE GAS-PHASE(CENTER)

Photochemistry resulting from excitation of a d-d transition at 575 nm between ligand-field states in the gas-phase [Cu-II(bpy)(serine-H)](.) complex generated by electrospray ionization is reported. These res ults are discussed in terms of a reaction scheme proposed by Turecek a nd co-workers [C.L. Gatlin, F, Turecek, T. Vaisar, J. Mass Spectrom. 3 0 (1995) 1617] for collisionally activated dissociation of this comple x at low center-of-mass collision energies under multiple-collision co nditions. Three photofragment ions are observed, corresponding to elim ination of formaldehyde, stepwise loss of formaldehyde followed by (OC )-O-.(OH)CHNH2, and transfer of a hydroxyl group to the Cu-II ion acco mpanied by loss of H2CCHNH2CO2. A fourth fragmentation channel reporte d by Turecek and co-workers corresponding to decarboxylation and assoc iated dehydration is also observed at moderate center-of-mass collisio n energies under single-collision conditions but is absent in the lase r photofragmentation difference mass spectrum resulting from excitatio n of [Cu-II(bpy)(serine-H)](+.) at 575 nm. (Int J Mass Spectrom 177 (1 998) 187-196) (C) 1998 Elsevier Science B.V.