A Novel Proton Sensor with Luminescence and Color Signaling Based on Platinum(II) Terpyridyl Acetylide Complex

Molecular switches that are controllable, reversible and readable at molecular level are an essential compo-nent of molecular electronics1 and chemical sensors.2-6 Of particular interest are the molecules which show dramatic and reversible changes in color and/or lumi-nescence in visible spectral region upon exposure to specific substrates. A number of chromophore- spacer-receptor systems that can selectively recognize specific guest molecules at their receptor site and pro-duce measurable col…     

一种2-甲基-3-羟基喹啉-4-甲酸单核铜(Ⅱ)配合物的合成、晶体结构、理论计算与性质

以2-甲基-3-羟基喹啉-4-甲酸和1,10-菲咯啉为原料,经溶剂热法合成了一种新颖的Cu(Ⅱ)配合物,[Cu(L)(Phen)(H_2O)]·CH_3OH(1,HL=2-甲基-3-羟基喹啉-4-甲酸,Phen=1,10-菲咯啉),并通过红外光谱、元素分析、单晶衍射、固态漫反射、光致发光及理论计算对其结构和性质进行了研究。单晶结构分析表明配合物1的晶体属于单斜晶系,P2_1/c空间群,是一种零维(0D)结构的单核体。固态光致发光表明其为蓝紫色光发射体。时间密度泛函理论(TDDFT)计算表明其发射归属于配体-配体电荷转移(LLCT)。固态漫反射测量显示该化合物存在1.91 eV的窄带能隙。     

Efficient charge separation in TiO2 films sensitized with ruthenium(II)-polypyridyl complexes: hole stabilization by ligand-localized charge-transfer states

We have studied the interfacial electron-transfer dynamics on TiO(2) film sensitized with synthesized ruthenium(II)-polypyridyl complexes--[Ru(II)(bpy)(2)(L(1))] (1) and [Ru(II)(bpy)(L(1))(L(2))] (2), in which bpy=2,2'-bipyridyl, L(1)=4-[2-(4'-methyl-2,2'-bipyridinyl-4-yl)vinyl]benzene-1,2-diol, and L(2)=4-(N,N-dimethylaminophenyl)-2,2'-bipyridine-by using femtosecond transient absorption spectroscopy. The presence of electron-donor L(2) and electron-acceptor L(1) ligands in complex 2 introduces lower energetic ligand-to-ligand charge-transfer (LLCT) excited states in addition to metal-to-ligand (ML) CT manifolds of complex 2. On photoexcitation, a pulse-width-limited (<100 fs) electron injection from populating LLCT and MLCT states are observed on account of strong catecholate binding on the TiO(2) surface. The hole is transferred directly or stepwise to the electron-donor ligand (L(2)) as a consequence of electron injection from LLCT and MLCT states, respectively. This results an increased spatial charge separation between the hole residing at the electron-donor (L(2)) ligand and the electron injected in TiO(2) nanoparticles (NPs). Thus, we observed a significant slow back-electron-transfer (BET) process in the 2/TiO(2) system relative to the 1/TiO(2) system. Our results suggest that Ru(II) -polypyridyl complexes comprising LLCT states can be a better photosensitizer for improved electron injection yield and slow BET processes in comparison with Ru(II)-polypyridyl complexes comprising MLCT states only.     

[N-ethyl-4,4＂-bipyridinium] [ZnX4] （X = CI or Br） with N-ethyl-4,4＂-bipyridinium Generated In Situ： Syntheses,Structures, Fluorescence and TDDFT Calculations

Two new zinc bipyridinium compounds, [N-ethyl-4,4＂-bipyridinium][ZnX4] （X = CI （1） or Br （2）） with N-ethyl-4,4＂-bipyridinium generated in situ, have been synthesized through solvothermal reactions and structurally characterized by single-crystal X-ray diffraction analyses. Both compounds are isostructural and crystallize in the P2/c space group of monoclinic system. Compound 1： a = 8.4397（5）, b = 21.988（1）, c = 8.8777（5） А, β = 106.490（1）°, V = 1579.7（2） A3, C2H15C14N2Zn, Mr = 394.43, Z = 4, Dc = 1.658 g/cm3, S = 1.068,/a（MoKa） = 2.218 mm-1, F（000） = 796, R = 0.0295 and wR = 0.0766. Compound 2： a = 8.4154（6）, b = 22.844（2）, c = 9.0308（7） A, fl = 106.026（1）°, V = 1668.6（2） A3, Cj/HjsBraN2Zn, Mr = 572.27, Z = 4, Dc = 2.278 g/cm3, S = 1.033, /l（MoKa） = 11.038 mm＂1, F（000） = 1084, R = 0.0427 and wR = 0.1175. Both of them are characteristic of an isolated structure with the zinc atoms locating at a tetrahedral environment. In both compounds, the N-ethyl-4,4＂-bipyridinium2＋ cations and ZnX42- anions interconnect together via hydrogen bonding interactions to construct a three-dimensional （3-D） supramolecular framework. Fluorescent studies reveal that both compounds exhibit a strong emission in the green region. In combination with the theoretical calculations, we can draw a conclusion that the emissions should result from ligand-to- ligand charge-transfer （LLCT） transition.     

[N-ethyl-4,4'-bipyridinium][ZnX_4](X = Cl or Br) with N-ethyl-4,4'-bipyridinium Generated In Situ:Syntheses,Structures, Fluorescence and TDDFT Calculations

Two new zinc bipyridinium compounds, [N-ethyl-4,4′-bipyridinium][ZnX4](X = Cl(1) or Br(2)) with N-ethyl-4,4′-bipyridinium generated in situ, have been synthesized through solvothermal reactions and structurally characterized by single-crystal X-ray diffraction analyses. Both compounds are isostructural and crystallize in the P21/c space group of monoclinic system. Compound 1: a = 8.4397(5), b = 21.988(1), c = 8.8777(5) , β = 106.490(1)°, V = 1579.7(2) 3, C12H15Cl4N2 Zn, Mr = 394.43, Z = 4, Dc = 1.658 g/cm3, S = 1.068, μ(MoKα) = 2.218 mm-1, F(000) = 796, R = 0.0295 and wR = 0.0766. Compound 2: a = 8.4154(6), b = 22.844(2), c = 9.0308(7) , β = 106.026(1)°, V = 1668.6(2) 3, C12H15Br4N2 Zn, Mr = 572.27, Z = 4, Dc = 2.278 g/cm3, S = 1.033, μ(MoKα) = 11.038 mm-1, F(000) = 1084, R = 0.0427 and wR = 0.1175. Both of them are characteristic of an isolated structure with the zinc atoms locating at a tetrahedral environment. In both compounds, the N-ethyl-4,4′-bipyridinium2+ cations and ZnX42– anions interconnect together via hydrogen bonding interactions to construct a three-dimensional(3-D) supramolecular framework. Fluorescent studies reveal that both compounds exhibit a strong emission in the green region. In combination with the theoretical calculations, we can draw a conclusion that the emissions should result from ligand-toligand charge-transfer(LLCT) transition.     

A Novel Proton Sensor with Luminescence and Color Signaling Based on Platinum（Ⅱ） Terpyridyl Acetylide Complex

A novel sensitive probe for proton based on platinum(Ⅱ) terpyridyl acetylide complex by monitoring the changes both in luminescence and color is described.     

Spectral and photophysical properties of mono and dinuclear Pt(II) and Pd(II) complexes: An unusual emission behaviour

Eight mononuclear complexes of the formula [M(N-N)(DHB)] and two binuclear complexes of the formula [M₂(BPY)₂(THB)] where M = Pd(II) or Pt(II), N-N = 2,2′-bipyridine (BPY), 2,2′-biquinoline (BIQ), 4,7-diphenyl-1,10-phenanthroline (DPP), 1,10-phenanthroline (PHEN); DHB = dianion of 3,4-dihydroxybenzaldehyde and THB = tetraanion of 3,3′,4,4′-tetrahydroxy benzaldazine were prepared and their electrochemical, spectral and photophysical properties were examined. These complexes were characterized by chemical analysis, IR and proton NMR spectroscopy. A detailed study on the absorption spectroscopy of these complexes was made. These complexes were found to show a low-energy solvatochromic ligand-to-ligand charge-transfer (LLCT) band. The electronic energies of these bands have been analyzed and compared with electrochemical data. Emission behaviour of the complexes of the series, [Pt(N-N)(DHB)], [Pt(N-N)(DHBA)] where DHBA is the dianion of 3,4-dihydroxybenzoic acid and [Pt₂(BPY)₂(THB)] was also investigated. These platinum complexes were found to emit from a low-energy state at low temperature and a high-energy state at room temperature. Photophysics of these complexes is also discussed.     

Molecule in soft-crystal at ground and excited states: Theoretical approach

This account discusses first two computational methods which can be applied to electronic structure calculations of soft-crystals; one is a method composed of the periodic-density functional theory (DFT) for an infinite crystal and the post-Hartree-Fock method for a cluster model, named here cluster-model/periodic-model combined method (abbreviated as CM/PM-Combined method). The other is a quantum mechanics/periodic-molecular mechanics (named QM/Periodic-MM) method, in which a target molecule is calculated by the DFT or the post-Hartree-Fock method and the other moiety is calculated by the MM method under the periodic boundary condition. Then, the performance of these two methods is discussed. The CM/PM-Combined method exhibited good performance for investigating the gas adsorption into MOF and the QM/Periodic-MM succeeded in reproducing geometry of single crystal of platinum(II) complexes. The QM/periodic-MM method has been applied to theoretical studies of the excited state and the emission spectrum in soft-crystals: In a theoretical study of a gold(I) phenyl phenylisocyanide complex, the geometries of a triplet ligand-to-ligand charger transfer (³LLCT) and a triplet metal-metal to ligand charge-transfer (³MMLCT) excited states were optimized in the crystal and the dependences of absorption and emission energies on crystal phase were discussed. In a theoretical study of a platinum(II) dicyano bipyridine complex, the geometries of several delocalized ³MMLCT excited states, emission spectra, and their temperature dependences were investigated in the crystal. In both gold(I) and platinum(II) complexes, the characteristic features of the excited state and the emission spectra were elucidated by the theoretical calculations. Although the CM/PM-Combined method has not been applied to photochemistry issue, brief discussion is presented for its possibility for the application.