title: Nickel complex with internal bases as efficient molecular catalyst for photochemical H2 production.
abstract: A Ni complex with internal bases that contain bipyridine-derived ligands, [Ni(L)2 (H2 O)2 ](BF4 )2 ([1](BF4 )2 , L=2-(2-pyridyl)-1,8-naphthyridine), and a reference complex that bears analogous bipyridine-derived ligands but without an internal base, [Ni(L')3 ](BF4 )2 ([2](BF4 )2 , L'=2-(2-pyridyl)quinoline), were synthesized and characterized. The electrochemical properties of these complexes were studied in CH3 CN, H2 O, and a mixture of EtOH/H2 O. The fluorescence spectroscopic studies suggest that both dynamic and the sphere-of-action static quenching exist in the fluorescein Fl(2-) /[1](2+) and Fl(2-) /[2](2+) systems. These noble-metal-free molecular systems were studied for photocatalytic H2 generation. Under optimal conditions, the turnover number of H2 evolution reaches 3230 based on [1](2+) , whereas [2](2+) displays only approximately one third of the turnover of [1](2+) . A plausible mechanism for the catalytic H2 generation by [1](2+) is presented based on DFT calculations.
authors.affiliation: State Key Laboratory of Fine Chemicals, DUT-KTH Education and Research Centre on Molecular Devices, Dalian University of Technology (DUT), 116024 Dalian (PR China).
authors.forename: Yong
authors.initials: Y
authors.lastname: Yang
authors.forename: Mei
authors.initials: M
authors.lastname: Wang
authors.forename: Liqin
authors.initials: L
authors.lastname: Xue
authors.forename: Fengbo
authors.initials: F
authors.lastname: Zhang
authors.forename: Lin
authors.initials: L
authors.lastname: Chen
authors.forename: Mårten S G
authors.initials: MS
authors.lastname: Ahlquist
authors.forename: Licheng
authors.initials: L
authors.lastname: Sun
mesh_terms: D018360:Crystallography, X-Ray; D006859:Hydrogen / Q000737:chemistry*; D013058:Mass Spectrometry; D056004:Molecular Dynamics Simulation; D015394:Molecular Structure; D009532:Nickel / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D010777:Photochemistry; D011725:Pyridines / Q000138:chemical synthesis* / Q000737:chemistry; D011804:Quinolines / Q000138:chemical synthesis* / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D009942:Organometallic Compounds; D011725:Pyridines; D011804:Quinolines; D009532:Nickel; D006859:Hydrogen
keywords: density functional calculations; hydrogen; nickel; photochemistry; water splitting