Photophysical properties of copper(I) and zinc(II) complexes containing phosphinoquinoline ligands

Several copper(I) and zinc(II) complexes with 8-(diphenylphosphino)quinoline (PPh(2)qn) or 8-diphenylphosphinoquinaldine (PPh(2)qna) have been prepared. These ligands contain both imine and phosphine moieties, which can act as coordinating groups. X-ray analysis of the Cu(I) complexes reveals that [Cu(PPh(2)qn)(2)]PF6 (Cu-1) and [Cu(PPh(2)qn)(2)]PF6 (Cu-2), coordinated by two PPh(2)qn and PPh(2)qna ligands respectively, are obtained. In the Zn(II) complexes, a structural study shows that [ZnCl2(PPh(2)qn)] (Zn-1), [ZnBr2(PPh(2)qn)] (Zn-2) and [Znl(2)(PPh(2)qn)] (Zn-3) are coordinated by one PPh(2)qn ligand and two of the corresponding halogeno ligands (Cl-, Br- and I-). In the solid state Cu-1 and Cu-2 show luminescence which is assigned to a (MLCT)-M-3 transition involving pi* of the quinoline group, as shown in the [Cu(dmp)(diphosphine)](+) complexes; due to the reduced bulkiness of the coordination sphere around the copper atom, no emission is observed in solution. Zn-1 shows a similar emission band to that of free PPh(2)qn at both room temperature and 77 K. It suggests the emission bands should be assigned to a ligand-centered (LC) transition. In the solid state, it is found that the emissive energy of the complexes shift to lower energy and the energy depends on the halogeno ligands in the zinc complexes. (C) 2008 Elsevier Ltd. All rights reserved.