A new three-dimensional coordination polymer [Mn(2,3-pdc)(H2O)]n (2,3-pdc=pyridine-2,3-dicarboxylate) 1 has been hydrothermally synthesized and structurally characterized. The crystal belongs to the monoclinic system,space group P21/c with a=6.4168(5),b=10.7939(9),c=11.1549(10),β=94.733(4)o,V=769.98(11)3,Z=4,Mr=238.06,Dc=2.054 g/cm3,μ(MoKα)=1.707 mm-1,F(000)=476,Rint=0.0326,R=0.0499 and wR=0.1636 for 1564 observed reflections with I > 2σ(I). X-ray diffraction analyses reveal that the title compound is a three-dimensional coordination polymer consisting of one MnII center with a distorted octahedral environment arranged by four 2,3-pdc ligands and one water molecule.
＜正＞Graphitic carbon nitride （g-C3N4）, a metal-free semiconductor, is a promising new class of photocatalysts f...
Jingfeng Dong1,Mei Wang1,*,Xueqiang Li1,Lin Chen1,Yu He1,Licheng Sun1,2 1State Key Laboratory of Fine Chemicals,DUT-KTH Joint Education and Research Center on Molecular Devices,Dalian University of Technology(DUT),Dalian,116012,China 2Department of Chemistry,Royal Institute of Technology(KTH),Stockholm,10044 Sweden
Two new noble-metal-free molecular devices,[{Co(dmgH) 2 Cl}{Zn(PyTPP)}](1,dmgH = dimethyloxime,PyTPP = 5-(4pyridyl)-10,15,20-triphenylporphyrin) and [{Co(dmgH) 2 Cl}{Zn(apPyTPP)}](2,apPyTPP = 5-[4-(isonicotinamidyl)phenyl]10,15,20-triphenylporphyrin),for light-driven hydrogen generation were prepared and spectroscopically characterized.The zinc porphyrin photosensitizer and the Co III-based catalyst unit are linked by axial coordination of a pyridyl group in the periphery of zinc-porphyrin to the cobalt centre of catalyst with different lengths of bridges.The apparent fluorescence quenching and lifetime decays of 1 and 2 were observed in comparison with their reference chromophores,Zn(PyTPP)(3) and Zn(apPyTPP)(4),suggesting a possibility for an intramolecular electron transfer from the singlet excited state of zinc porphyrin unit to the cobalt centre in the molecular devices.Photochemical H2-evolving studies show that complexes 1 and 2 are efficient molecular photocatalysts for visible light-driven H2 generation from water with triethylamine as a sacrificial electron donor in THF/H2 O,with turnover numbers up to 46 and 35 for 1 and 2,respectively.In contrast to these molecular devices,the multicomponent catalyst of zinc porphyrin and [Co(dmgH) 2 PyCl] did not show any fluorescence quenching and as a consequence,no H2 gas was detected by GC analysis in the presence of triethylamine with irradiation of visible light.The plausible mechanism for the photochemical H2 generation with these molecular devices is discussed.
A new mixed-ligand Mn(II)complex,namely [Mn(bipy)2(Huca)]·5H2O(1,bipy = 2,2'-bipyridine,and H3uca = uracil-5-carboxylic acid)has been prepared and characterized by single-crystal X-ray diffraction,FT-IR spectroscopy and thermogravimetric analysis.It crystallizes in monoclinic,space group C2/c with a = 23.597(8),b = 16.434(5),c = 15.531(6),β = 112.785(6)o,C25H28MnN6O9,Mr = 611.47,V = 5553(3)3,Z = 8,μ = 0.538,Dc = 1.463 g/cm3,F(000)= 2536,R = 0.0441 and wR = 0.1230 for all 5227 observed reflections(I > 2σ(I)).The manganese(II)center is surrounded by three bidentate chelating ligands,and it displays a severely distorted octahedral geometry,with cis angles ranging from 72.14(6)to 109.78(6)o.Extensive intermolecular hydrogen bonds link the [Mn(bipy)2(Huca)] monomers and lattice water molecules to yield a three-dimensional supramolecular framework.TGA shows complete removal of all lattice water molecules above 270 ℃.
By use of a new ligand containing both salicylic acid moiety and salicylaldehyde Schiff base moiety, 5-(2-hydroxybenzylideneamino)-2-hydroxybenzoic acid (H3L), a linear trinuclear Mn(II) complex was prepared. This complex crystallizes in triclinic, space group P1 with a = 12.0196(7), b = 13.7440(13), c = 15.7554(14) , α = 111.529(3), β = 96.691(2), γ = 94.802(2)o, C96H100Mn3N6O32, Mr = 2014.64, V = 2382.0(3) 3, Z = 1, μ = 0.478, Dc = 1.404 g/cm3, F(000) = 1049, R = 0.0554 and wR = 0.1610 for 8973 observed reflections (I > 2σ(I)). The complex consists of a trinuclear cluster and two solvate ethanol molecules. Three linearly disposed Mn atoms, with an inversion center on the central one, are bridged by six carboxylate groups from six bulky mono-anionic ligands (H2L–), and the octahedral coordination spheres for each of the metal centers are thus formed, with the aid of additional ligation of two small molecules (ethanol and water) to both ends. The magnetic properties of the title complex are also included in this paper.
A cobalt-based catalyst was directly photo-deposited on the surface of a widely used n-type nano-structured semiconductor(TiO_(2)).Different thicknesses of the TiO 2 films as well as different time of photo-deposition of the Co-based catalyst on TiO_(2) films have been optimized.It was found that the electrode with 3 layers of TiO_(2) film(in 8 m thickness) and 1 hour photo-deposition of the cobalt-based catalyst by light irradiation from a 500 W Xenon lamp gave the highest current density(~5 mA/cm^(2)).Using this cobalt-modified TiO_(2) film as a working electrode in an electrochemical device,highly efficient water oxidation has been demonstrated in a pH 7.0 aqueous solution with low overpotential.
