铁（Ⅱ）配位聚合物电致变色材料研究进展

电致变色是一种响应外部电刺激而发生颜色变化的现象,材料可以在不同的氧化还原状态之间进行可逆切换,从而在可见光或近红外区域产生新的吸收带。迄今为止,电致变色材料主要包括过渡金属氧化物、过渡金属配位聚合物、紫罗精、有机共轭聚合物等。过渡金属配位聚合物类电致变色材料兼具无机材料和有机材料的优点,具有广泛的应用前景。铁配位聚合物具有良好的氧化还原性质和丰富的电子跃迁,是一类性能优异的电致变色材料。本文综述了铁金属配位聚合物类电致变色材料的研究进展,主要从有机配体的臂形、种类和间隔基团等方面进行分类阐述。     

Spectroscopic, cyclic voltammetric and biological studies of transition metal complexes with mixed nitrogen-sulphur (NS) donor macrocyclic ligand derived from thiosemicarbazide

The complexation of new mixed thia-aza-oxa macrocycle viz., 2,12-dithio-5,9,14,18-tetraoxo-7,16-dithia-1,3,4,10,11,13-hexaazacyclooctadecane containing thiosemicarba-zone unit with a series of transition metals Co(II), Ni(II) and Cu(II) has been investigated, by different spectroscopic techniques. The structural features of the ligand have been studied by EI-mass, (1)H NMR and IR spectral techniques. Elemental analyses, magnetic moment susceptibility, molar conductance, IR, electronic, and EPR spectral studies characterized the complexes. Electronic absorption and IR spectra of the complexes indicate octahedral geometry for chloro, nitrato, thiocyanato or acetato complexes. The dimeric and neutral nature of the sulphato complexes are confirmed from magnetic susceptibility and low conductance values. Electronic spectra suggests square-planar geometry for all sulphato complexes. The redox behaviour was studied by cyclic voltammetry, show metal-centered reduction processes for all complexes. The complexes of copper show both oxidation and reduction process. The redox potentials depend on the conformation of central atom in the macrocyclic complexes. Newly synthesized macrocyclic ligand and its transition metal complexes show markedly growth inhibitory activity against pathogenic bacterias and plant pathogenic fungi under study. Most of the complexes have higher activity than that of the metal free ligand.     

UV-vis-NIR and EPR characterisation of the redox series [MQ(3)](2+,+,0,-,2-), M = Ru or Os, and Q = o-quinone derivative

The neutral title compounds with Q = 3,5-di-tert-butyl-o-quinone or 4,6-di-tert-butyl-N-phenyl-o-iminobenzoquinone (Q(x)) were studied by UV-vis-NIR spectroelectrochemistry and by EPR spectroscopy in the case of the odd-electron monocation and monoanion intermediates. Supported by DFT and TD-DFT calculations, the results indicate stepwise electron removal from predominantly ligand-based delocalised MOs on oxidation whereas the stepwise electron uptake on reduction involves unoccupied MOs with considerably metal-ligand mixed character. In both cases, the strong near-infrared absorption of the neutral precursors diminishes. In comparison to the ruthenium series, the osmium analogues exhibit larger transition energies from enhanced MO splitting and a different EPR response due to the higher spin-orbit coupling. The main difference between the quinone (1(n), 2(n)) and corresponding monoiminoquinone systems (3(n), 4(n)) is the shift of about 0.6 V to lower potentials for the monoimino analogues. While the absorption features do not differ markedly, the EPR data reflect a higher degree of covalent bonding for the complexes with monoimino ligands.     

A combined experimental and theoretical approach for structural study on a new cinnamoyl derivative of 2-acetyl-1,3-indandione and its metal(II) complexes

The synthesis, structure and spectral properties of a new cinnamoyl derivative of 2-acetyl-1,3-indandione (2AID), p-fluoro-cinnamoyl-1,3-indandione, LH and its metal(II) complexes with Cu(II), Zn(II) and Cd(II), are described. In order to verify the molecular structure of the free ligand and its metal complexes, model geometries based on the spectroscopic data were optimized using quantum chemical methods. The experimental spectroscopic data (IR and NMR) of the ligand, LH, complemented by the calculated ones, show that it exists in the exocyclic enolic form in the gas phase, solution and solid state. Good quality single crystals of Cd(II) complex were obtained from a DMSO solution and were studied by means of single-crystal X-ray diffraction. The data show bidentate coordination of the ligand and two DMSO molecules coordinated to the metal centre, thus forming a complex with octahedral geometry. On the contrary, the spectroscopic data on the amorphous samples indicate a square planar geometry of the Cu(II) complex and distorted octahedral geometry for Zn(II) and Cd(II) complexes with two water molecules coordinated to the metal centre. The used quantum chemical method for structure optimization of the transition metal complexes, B3LYP/LANL2DZ, shows very good agreement with the crystallographic data and, therefore, was also employed for structural determination for the non-crystalline complexes. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Exploratory studies on coordination chemistry of a redox-active bridging ligand: synthesis, properties and solid state structures of the complexes

The explorative coordination chemistry of the bridging ligand TTF-PPB is presented. Its strong binding ability to Co(II) and then to Ni(II) or Cu(II) in the presence of hexafluoroacetylacetonate (hfac(-)), forming new mono- and dinuclear complexes 1-3, is described. X-ray crystallographic studies have been conducted in the case of the free ligand TTF-PPB as well as its complexes [Co(TTF-PPB)(hfac)(2)] (1) and [Co(hfac)(2)(μ-TTF-PPB)Ni(hfac)(2)] (2). Each metal ion is bonded to two bidentate hfac(-) anions through their oxygen atoms and two nitrogen atoms of the PPB moiety with a distorted octahedral coordination geometry. Specifically, nitrogen donor atoms of TTF-PPB adopt a cis-coordination but not in the equatorial plane, which is quite rare. Electronic absorption, photoinduced intraligand charge transfer ((1)ILCT), and electrochemical behaviour of 1-3 have been investigated. UV-Vis spectroscopy shows very strong bands in the UV region consistent with ligand centred π-π* transitions and an intense broad band in the visible region corresponding to a spin-allowed π-π* (1)ILCT transition. Upon coordination, the (1)ILCT band is bathochromically shifted by 3100, 6100 and 5900 cm(-1) on going from 1 to 3. The electrochemical studies reveal that all of them undergo two reversible oxidation and one reversible reduction processes, ascribed to the successive oxidations of the TTF moiety and the reduction of the PPB unit, respectively.     

Co(x)Cu(1-x)(DDOP)(OH2)(NO3)](NO3): hydrogen bond-driven distortion of cobalt(II) by solid solution 'network mismatch'

Late-first row transition metal nitrate complexes of the tetradentate N-donor ligand cis-3,5-bis[(2-pyridinyleneamino]-trans-hydroxycyclohexane (DDOP) adopt a mono-cationic [M(DDOP)(H(2)O)(NO(3))](+) structure (M = Co, 1; Cu, 2; Zn, 3) in which the DDOP ligand occupies the equatorial plane. The complexes are essentially isostructural and isomorphous, allowing the Co(II) and Cu(II) complexes to co-crystallize in mixed-metal solid solutions with the formula [Co(x)Cu(1-x)(DDOP)(NO(3))(H(2)O)](NO(3)), where x = 0.4 (4), 0.1 (5), and 0.7 (6). For 4, structural and magnetochemical analysis indicate that the geometry of the octahedral Co(II) complex distorts to match that of the dominant Jahn-Teller distorted Cu(II) center. Magnetic susceptibility data of octahedral Co(II) are sensitive to ligand geometry distortions and have been analyzed accordingly, comparing 4 to the reference systems 1 and 2. Bond valence calculations have been used to estimate the relative stabilities of the six hydrogen bonded networks, suggesting that the stretching of the Co(II) coordination sphere 4 in is assisted by adoption of the most stable hydrogen bonded network; but that in 6 this is overcome by a higher loading of Co. This family of complexes therefore represent predictable metal-based tectons which can help probe the influence of secondary non-covalent interactions over metal coordination geometries and properties.     

Substitutional mechanism of Ni into the wide-band-gap semiconductor InTaO4 and its implications for water splitting activity in the wolframite structure type

The mechanism of Ni substitution into the oxide semiconductor InTaO(4) has been studied through a combination of structural and spectroscopic techniques, providing insights into its previously reported photoactivity. Magnetic susceptibility and X-ray absorption near-edge spectroscopy (XANES) measurements demonstrate that nickel is divalent within the host lattice. The combined refinement of synchrotron X-ray and neutron powder diffraction data indicates that the product of Ni doping has the stoichiometry of (In(1-x)Ni(2x/3)Ta(x/3))TaO(4) with a solubility limit of x ≈ 0.18, corresponding to 12% Ni on the In site. Single-phase samples were only obtained at synthesis temperatures of 1150 °C or higher due to the sluggish reaction mechanism that is hypothesized to result from small free energy differences between (In(1-x)Ni(2x/3)Ta(x/3))TaO(4) compounds with different x values. Undoped InTaO(4) is shown to have an indirect band gap of 3.96 eV, with direct optical transitions becoming allowed at photon energies in excess of 5.1 eV. Very small band-gap reductions (less than 0.2 eV) result from Ni doping, and the origin of the yellow color of (In(1-x)Ni(2x/3)Ta(x/3))TaO(4) compounds instead results from a weak (3)A(2g) → (3)T(1g) internal d → d transition not associated with the conduction or valence band that is common to oxide compounds with Ni(2+) in an octahedral environment.     

Quantification of the trans influence in d8 square planar and d6 octahedral complexes: a database study

A systematic search of the Cambridge structural database was undertaken to quantify the trans influence in square planar and octahedral transition metal compounds. For square planar geometry, d⁸ metal centers were studied, while octahedral searches focused on low-spin d⁶ complexes. Two probe ligands (PL) were used to measure the effect of the trans ligand (TL), chloride, and triphenylphosphine (PPh₃). For the TLs O=CX₂, NR₃, pyridine, and Cl^? (X?=?any non-metal, R?=?H or hydrocarbon), the effects on the metal–probe ligand (M–PL) distance were statistically equal and were taken as essentially no trans influence. The other ligands studied showed significant decrease in the mean M–PL bond order, relative to the above ligands: SR₂?=?0.941; S=CX₂?=?0.887; PPh₃?=?0.825; phenyl?=?0.743; CR₃?=?0.719; hydride?=?0.685. Some variation in the trans influence is observed, based on the geometry of the metal center and the PL. In general, electron-donating, σ-bonding ligands lead to a larger trans influence, but π-bonding effects can also be important, particularly when the probe ligand also has π-bonding properties.     

Phenoxide bridged tetranuclear Co(II), Ni(II), Cu(II) and Zn(II) complexes: electrochemical, magnetic and antimicrobial studies

Phenoxide bridged later first row transition metal(II) complexes have been prepared by the interaction of later 3d transition metal(II) chlorides with tetranucleating compartmental Schiff base ligand system derived from 2,6-diformyl-4-methylphenol, p-phenylenediamine and 2-hydrazinobenzothiazole. Ligand and complexes were characterized by analytical, spectral (IR, UV-visible, ESR, FAB-mass and fluorescence), magnetic and thermal studies. All complexes are found to have octahedral geometry. The mutual influence of metal centres in terms of cooperative effect on the electronic, magnetic, electrochemical and structural properties was investigated. The Schiff base and its complexes have been screened for their antibacterial (against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa) and antifungal activities (against Aspergillus niger, and Candida albicans).     

Platinum acetylide two-photon chromophores

To explore the photophysics of platinum acetylide chromophores with strong two-photon absorption cross-sections, we have investigated the synthesis and spectroscopic characterization of a series of platinum acetylide complexes that feature highly pi-conjugated ligands substituted with pi-donor or -acceptor moieties. The molecules (numbered 1-4) considered in the present work are analogs of bis(phenylethynyl)bis(tributylphosphine)platinum(II) complexes. Molecule 1 carries two alkynyl-benzothiazolylfluorene ligands, and molecule 2 has two alkynyl-diphenylaminofluorene ligands bound to the central platinum atom. Compounds 3 and 4 possess two dihexylaminophenyl substituents at their ends and differ by the number of platinum atoms in the oligomer "core" (one vs two in 3 and 4, respectively). The ligands have strong effective two-photon absorption cross-sections, while the heavy metal platinum centers give rise to efficient intersystem crossing to long-lived triplet states. Ultrafast transient absorption and emission spectra demonstrate that one-photon excitation of the chromophores produces an S1 state delocalized across the two conjugated ligands, with weak (excitonic) coupling through the platinum centers. Intersystem crossing occurs rapidly (Kisc approximately 1011 s-1) to produce the T1 state, which is possibly localized on a single conjugated fluorenyl ligand. The triplet state is strongly absorbing (epsilonTT > 5 x 104 M-1 cm-1), and it is very long-lived (tau > 100 micro s). Femtosecond pulses were used to characterize the two-photon absorption properties of the complexes, and all of the chromophores are relatively efficient two-photon absorbers in the visible and near-infrared region of the spectrum (600-800 nm). The complexes exhibit maximum two-photon absorption at a shorter wavelength than 2lambda for the one-photon band, consistent with the dominant two-photon transition arising from a two-photon-allowed gerade-gerade transition. Nanosecond transient absorption experiments carried out on several of the complexes with excitation at 803 nm confirm that the long-lived triplet state can be produced efficiently via a sequence involving two-photon excitation to produce S1, followed by intersystem crossing to produce T1.     

Structure and properties of a series of 2-cinnamoyl-1,3-indandiones and their metal complexes

A series of seven 2-cinnamoyl-1,3-indandiones and their metal(II) complexes were synthesized and characterized by means of spectroscopic (IR, NMR, electron absorption and emission spectroscopy) and/or single-crystal X-ray diffraction methods. The optical spectra of the organic compounds show very strong absorption in the visible region and weak fluorescence with moderate to strong Stokes shift. The effect of concentration, water addition and metal ion complexation on the optical properties was also studied. In search of potential practical application, the complexation of 2-cinnamoyl-1,3-indandiones with metal(II) ions was investigated. A series of non-charged complexes with Cu(II), Cd(II), Zn(II), Co(II) and Ni(II) was isolated and analyzed by elemental analyses and IR. Most of the complexes show presence of water molecules, most probably coordinated to the metal ion, thus forming octahedral geometry. For the paramagnetic Cu(II) complexes a distorted, flattened tetrahedral structure is proposed, basing on the EPR data. The optical properties of the metal complexes, however, do not differ appreciably from those of the free ligands.     

Lanthanide Inorganic Solids Based on Main Group Borates and Oxyanions of Lone Pair Cations

Lanthanide 硼酸盐包含柱子转变金属主要的组元素,包括的 Ga ( III ), Ge ( IV ), Sb (V)和 Te ( VI ),以及孤独的对阳离子的 oxyanions 的 lanthanide 盐,例如我(V), Se ( IV )和 Te ( IV ),被考察。柱子转变金属在 lanthanide 硼酸盐的主要的组元素仅仅采用八面或有四面的几何学。在 lanthanide galloborates 的结构,当两八面的 GeO ₆ 和有四面的 GeO ₄ 出现在 borogermanates 时,仅仅八面的高 ₆ 被发现。第五时期元素 Sb (V) 和 Te (VI ) 在 lanthanide 硼酸盐系统比较喜欢八面的协作几何学。介绍给孤独的对的 lanthanide oxyanions 的第二个组主要那么集中于 d ⁰ TM 单位,例如 WO ₄ 四面体, VO ₅ 平方金字塔或哞 ₆ 八面体,和象硫酸盐一样的僵硬的有四面的组 ₄, 硅石 SiO ₄ 或硒酸盐 SeO ₄ 单位。象 Pb (II ) 和 Cu (II ) 或 Mn (II ) 的磁性的离子一样的二价的阳离子也被包括。在这些系统的 lanthanide 离子的结构化学是富有的。从六～十的协作数字被发现,产出包括五角的 bipyramid 的大量协作几何学,方形的 antiprism, metabidiminished 二十面体, tricapped 三角的棱柱,盖住的三角形的小圆屋顶,等等。在行 polyhedra 之间的连接模式是其他的,从 3D 网络,到 2D 层, 1D 链, tetramer,更整齐,更暗淡并且最后单体。很多混合物显示 NCS 结构和强壮的 SHG 反应,和许多 lanthanide 混合物展出好光性质在可见并且红外区域。     

A Hexagonal Planar Metal Complex

A six‐coordinate [ML₃Z₃]‐type transition‐metal complex with a hexagonal planar geometry has been isolated and characterized, extending the scope of six‐coordinate metal coordination compounds to those with a geometry beyond octahedral and trigonal prismatic.     

Cyclometallated iridium and platinum complexes with noninnocent ligands

The electronic properties of the cyclometalated (CwedgeN) complexes of iridium and platinum metals with a catechol ligand have been studied experimentally and computationally. The synthesis and characterization of (p-tolylpyridine)Ir(3,5-di-tert-butylcatechol) (abbreviated Ir-sq) and (2,4-diflorophenylpyridine)Pt(3,5-di-tert-butylcatechol) (abbreviated Pt-sq) are reported along with their structural, spectral, and electrochemical properties. Reaction of the 3,5-di-tert-butylcatechol (DTBCat) ligand with the prepared cyclometalated metal complex was carried out in air in the presence of a base. The resulting complexes are air stable and are paramagnetic with the unpaired electron residing mainly on the catechol ligand. The bond lengths obtained from X-ray structure analysis and the theoretical results suggest the semiquinone form of the catechol ligand. Low-energy, intense (approximately 10(3) M-1 cm-1) transitions are observed in the visible to near-infrared region (600-700 nm) of the absorption spectra of the metal complexes. Electrochemically, the complexes exhibit a reversible reduction of the semiquinone form to the catechol form of the ligand and an irreversible oxidation to the unstable quinone form of the ligand. The noninnocent catechol ligand plays a significant role in the electronic properties of the metal complexes. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations on the two open-shell molecules provide the ground-state and excited-state energies of the molecular orbitals involved in the observed low-energy transitions. The spin density in the two complexes resides mainly on the catechol ligand. The intense transition arises from excitation of the beta electron from a HOMO-n (n = 1 or 2 here) to the LUMO, rather than from the excitation of the unpaired alpha electron.     

Synthesis of novel coordination compounds of substituted guanidinopyrimidines with ruthenium

The synthesis, characterization, and mechanistic investigation of the coordination compounds of ruthenium with aminoguanidino- substituted ligands are described. These compounds usually possess octahedral, six-coordinate geometry as opposed to the square planar arrangement of the ligand of dicarboxylatoplatinum(II) carboplatin or cis-diamminodichloroplatinum(II) – cis-platin. The electronic and i.r. absorption spectra of these new chelates are discussed.     

Morphology-controlled synthesis of W18O49 nanostructures and their near-infrared absorption properties

The morphology-controlled synthesis and near-infrared (NIR) absorption properties of W(18)O(49) were systematically investigated for the application of innovative energy-saving windows. Various morphologies of W(18)O(49), such as nanorods, nanofibers, nanograins, nanoassembles, nanoplates, and nanoparticles, with various sizes were successfully synthesized by solvothermal reactions using organic alcohols as reaction media and WCl(6), W(EtO)(6), and WO(3) solids as the tungsten source. W(18)O(49) nanorods of less than 50 nm in length showed the best optical performance as an effective solar filter, which realized high transmittance in the visible region as well as excellent shielding properties of NIR light. Meanwhile, the W(18)O(49) nanorods also exhibited strong absorption of NIR light and instantaneous conversion of the absorbed photoenergy to the local heat.     

Ambient Temperature Synthesis and Structural Characterization of Six Transition Metal Acetylenedicarboxylate Coordination Polymers

This work reports the ambient temperature synthesis and structural characterization of six new first row transition metal acetylenedicarboxylate coordination polymers. The Co and two Ni compounds adopt structures in which the octahedral metals are connected into 1D chains via the acetylenedicarboxylate ligand. In contrast the Mn and two Zn compounds adopt 3D metal-organic frameworks; while the Mn compound is non-porous the two Zn structures contain dimeric or trimeric clusters connected into frameworks that are potentially porous. These two anionic metal-organic frameworks are, however, charged balanced by cations siting in their pores which greatly reduces the ability to access their porosity.     

Near-infrared luminescence of nine-coordinate neodymium complexes with benzimidazole-substituted 8-hydroxyquinolines

A new class of benzimidazole-substituted 8-hydroxyquinoline ligands has been prepared that contain a monoanionic tridentate N,N,O-coordinating unit. These ligands form charge-neutral lanthanide complexes of the type [Ln(L-R) 3]. nH 2O or [Ln 2(L2) 3]. nH 2O ( n = 1-3) with early lanthanides from La (III) to Gd (III) inclusive. Crystallographic characterization was carried out for 11 complexes with 6 different ligands. In all of these structures, the lanthanide ion was found to be nine-coordinated by three ligands arranged in an "up-up-down" fashion around the metal center. The coordination environment can be described as a tricapped trigonal prism, with N atoms of quinoline rings occupying capping positions. Upon deprotonation of the ligand and complex formation, a new absorption band appears in the visible range of the spectrum with a maximum in the range of 466-483 nm and molar absorption coefficient of (7.2 - 18) x 10 (3) M (-1) cm (-1). Its origin is likely to be an intraligand phenolate-to-pyridyl charge transfer transition centered on the 8-hydroxyquinolate chromophore. Upon excitation in ligand absorption bands, new Nd (III) complexes display characteristic metal-centered luminescence in the near-infrared region from 850 to 1450 nm with quantum yields and lifetimes in solid state at room temperature as high as 0.34% and 1.2 mus, respectively.     

Seven-coordination versus six-coordination in divalent first-row transition-metal complexes derived from 1,10-diaza-15-crown-5

The complexes of the heptadentate receptor N,N'-bis(benzimidazol-2-ylmethyl)-1,10-diaza-15-crown-5 (L2) with MnII, CoII, NiII, CuII, and ZnII are reported. The X-ray crystal structures of the ZnII and NiII complexes show that whereas the ZnII ion is seven-coordinated in a (distorted) pentagonal-bipyramidal coordination environment, the NiII ion is only six-coordinated in a distorted octahedral coordination environment. Theoretical calculations on the [M(L2)]2+ systems (M = Mn, Co, Ni, Cu, or Zn) performed at the density functional theory (DFT; B3LYP) level have been used to obtain information about the structure and electronic properties of these complexes, as well as to rationalize their preferences for a pentagonal-bipyramidal or an octahedral coordination. We have found that for the MnII, CoII, CuII, and ZnII complexes, geometry optimizations lead systematically to pentagonal-bipyramidal coordination environments around the metal ions. However, for the NiII complex, two minimum-energy conformations were obtained, with the metal ion being in octahedral (o-[Ni(L2)]2+) or pentagonal-bipyramidal (pb-[Ni(L2)]2+) coordination. The stabilization of the octahedral geometry in the NiII complex can be considered as the result of the Jahn-Teller effect operating in pentagonal-bipyramidal geometry, which in an extreme case leads to an octahedral coordination. Spectrophotometric titrations carried out in dimethyl sulfoxide (DMSO) and CH3CN/DMSO (9:1) solutions indicate the following stability sequence for the complexes of L2: CoII approximately NiII > ZnII > MnII. The variations in the geometry and stability of the complexes may be rationalized in terms of the different occupations of the frontier molecular orbitals along the first-row transition-metal series. Finally, a time-dependent DFT approach was used to investigate the absorption spectrum of the [Cu(L2)]2+ complex based on the optimized geometries at the B3LYP level, also confirming a pentagonal-bipyramidal coordination in solution for this compound.     

The triruthenium complex [[(acac)2Ru(II)]3(L)] containing a conjugated diquinoxaline[2,3-a:2',3'-c]phenazine (L) bridge and acetylacetonate (acac) as ancillary ligands. Synthesis, spectroelectrochemical and EPR investigation

The compound [[(acac)2Ru]3(L)] (1) undergoes three well-separated one-electron oxidation and reduction processes. The EPR results indicate electron removal from the ruthenium(II) centres on oxidation and the occupation of a largely L-based molecular orbital on reduction. In spite of well-separated (DeltaE > or = 340 mV) oxidation no obvious intervalence charge transfer bands were detected in the Vis, NIR or IR regions, suggesting very weak electronic coupling between the metal centres in the mixed-valent intermediates 1+ and 1(2+). The separated (DeltaE > or = 540 mV) stepwise reduction produces weak near-infrared features associated with partially occupied pi* orbitals of L, the unusually high g anisotropy in the EPR spectrum of 1- is attributed to the occupation of a degenerate MO by the unpaired electron.