title: Luminescence of five-coordinated nickel(ii) complexes with substituted-8-hydroxyquinolines and macrocyclic ligands.
abstract: A series of heteroleptic quinolinolate pentacoordinated nickel(ii) complexes, [Ni(mcN(3))(R(1),R(2),R(3)-8-hq)](PF(6)), were synthesized and characterized by spectroscopic methods. Single-crystal X-ray diffraction studies for [(Me(3)-mcN(3))Ni(N,O-2-CN-8-hq)][PF(6)] (6a), [(Me(4)-mcN(3))Ni(N,O-8-hq)][PF(6)] (2b) and [(Me(4)-mcN(3))Ni(N,O-5,7-I(2)-8-hq)][PF(6)] (5b) indicate that these complexes consist of a square-pyramidal ligand arrangement containing one chelating quinolinolate and one macrocyclic ligand (mcN(3)). Variation of the substituents on quinolinolate ligands imposes obvious electronic or structural effects on the nickel atom. These chromophores absorb moderately in the visible region and emit in the yellowish-green spectral region from a quinolinolate-centered intraligand charge-transfer excited state. The emission maxima are in the range 520-548 nm, with quantum yields between 0.11 and 1.63%, in deoxygenated organic solvents at room temperature. TD-DFT calculations allow exploration of the photophysical properties of complex [(Me(4)-mcN(3))Ni(N,O-8-hq)][PF(6)] and reveal the influence of the quinolinolate ligand on the HOMO/LUMO energies and oscillator strengths.
authors.affiliation: Departamento de Química Inorgánica, Universidad de Murcia, 30071, Murcia, Spain. dsl@um.es
authors.forename: M Dolores
authors.initials: MD
authors.lastname: Santana
authors.forename: Rocío
authors.initials: R
authors.lastname: García-Bueno
authors.forename: Gabriel
authors.initials: G
authors.lastname: García
authors.forename: José
authors.initials: J
authors.lastname: Pérez
authors.forename: Luis
authors.initials: L
authors.lastname: García
authors.forename: Miguel
authors.initials: M
authors.lastname: Monge
authors.forename: Antonio
authors.initials: A
authors.lastname: Laguna
mesh_terms: D003198:Computer Simulation; D018360:Crystallography, X-Ray; D008024:Ligands; D049449:Luminescence; D047028:Macrocyclic Compounds / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D008958:Models, Molecular; D015394:Molecular Structure; D009532:Nickel / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D015125:Oxyquinoline / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D008024:Ligands; D047028:Macrocyclic Compounds; D009942:Organometallic Compounds; D015125:Oxyquinoline; D009532:Nickel