Electrochromic performance and ion sensitivity of a terthienyl based fluorescent polymer

A novel terthienyl based fluorescent polymer bearing strong electron-withdrawing substituents directly attached to the 3,4-positions of the central thiophene ring was synthesized by electrochemical polymerization of diethyl 2,5-di(3,4-ethylenedioxythiophen-2-yl)thiophene-3,4-dicarboxylate. The corresponding polymer was characterized by cyclic voltammetry, FT-IR and UV–vis spectroscopy. The polymer has a well-defined redox process (E_p,1/2 = 0.74 V) and demonstrates a reversible electrochromic behavior; lilac in the neutral state and transparent sky blue in the oxidized state. Also, the polymer had low band gap (E_g = 1.82 eV) and high redox stability (retaining 94.0% of its electro-activity after 500th switch). Moreover, the sensitivity of both the monomer and its polymer towards metal cations was investigated by monitoring the change in the fluorescence intensity. Among various common ions both the monomer and its polymer were found to be selective towards Cu²⁺ and Cu⁺ ions by quenching the fluorescence efficiency with a Stern–Volmer constant (K_sv) of (1.4–1.6 × 10³ M^?1) and (1.5–1.8 × 10² M^?1) for monomer and polymer solutions, respectively.     

The first example of extended structure constructed from Knoth-type sandwich POMs and coordination fragments

A novel compound [P₂W₁₈M₃O₆₈][Cu(en)₂]₄·7H₂O·2OH^? (M = 0.5W + 0.5Cu) 1 which contains the first example of extended structure constructed from Knoth-type sandwich polyoxoanions and transition metal coordination complexes has been hydrothermally synthesized and characterized by elemental analysis, IR spectrum, UV–Vis spectrum and single-crystal X-ray diffraction analysis. Crystal data for 1: triclinic, space group, P-1, a = 13.2718(7) Å, b = 13.6432(8) Å, c = 25.7307(15) Å, α = 104.7340(10)°, β = 96.7630(10)°, γ = 90.0330(10)°, V = 4472.2(4) Å³, Z = 2. Structure solution and refinement based on 1090 parameters gave R1 (wR2) = 0.0409 (0.0993).     

Microwave dielectric properties of (Zn1/3B2/3)0.5(Ti0.8M0.2)0.5O2 (B = Nb5+, Ta5+, M = Sn4+, Ge4+) ceramics

Dielectric properties of (Zn_1/3Nb_(2?x)/3Ta_x/3)_0.5(Ti_0.8Sn_0.1Ge_0.1)_0.5O₂ (x = 0, 1, 2) and/or (Zn_1/3Nb_1/3Ta_l/3)_0.5(Ti_0.8Sn_0.2(l?y)Ge_0.2y)_0.5O₂ (y = 0, 0.5, 1) were investigated at the microwave frequencies. For the compositions with single phase of rutile structure, the dielectric constant (K) of specimens was not only dependent on the dielectric polarizabilities, but also on the bond length ratio of apical bond (d_apical) to equatorial bond (d_equatorial) of oxygen octahedron in the unit cell. Temperature coefficients of the resonant frequencies (TCF) of the specimens with B = Nb⁵⁺ and/or M = Sn⁴⁺ was larger than those with B = Ta⁵⁺ and/or M = Ge⁴⁺. These results could be attributed to the changes of the degree of oxygen octahedral distortion. Quality factors (Qf) of the specimens with B = Ta⁵⁺ and/or M = Sn⁴⁺ were larger than those with B = Nb⁵⁺ and/or M = Ge⁴⁺.     

Layered mixed-anion compounds: Epitaxial growth,active function exploration,and device application

Optoelectronic properties and device applications of layered mixed-anion compounds such as oxychalcogenide LaCuOCh (Ch = chalcogen) and oxypnictide LaT_MOPn (T_M = 3d transition metal, Pn = pnicogen) are reviewed. Several distinctive functions have been found in these materials based on our original material exploration concept. Fabrication of high-quality epitaxial films of LaCuOCh leads to clarifying the excellent electrical and optical properties such as high hole mobility of 8 cm²/(V s) and heavy hole doping at >10²¹ cm^?3 in LaCuOSe, and sharp and tunable-wavelength photoluminescence in the solid–solution systems in LaCuOCh. In addition, a room temperature operation of a light-emitting diode is demonstrated using LaCuOSe as a light-emitting layer. These results suggest that the layered oxychalcogenides have potential for light-emitting layers as well as transparent hole-injection layers in organic/inorganic light-emitting diodes. Furthermore, by extending the material system from the copper-based oxychalcogenides to isostructural compounds, transition metal-based oxypnictides LaT_MOP (T_M = Fe, Ni), we have found novel superconductors, LaFeOP and LaNiOP.     

Construction and photoluminescence properties of two novel zinc(II) and cadmium(II) benzyl-tetrazole coordination polymers

Two new d¹⁰ coordination polymers, Zn(Beta)₂ (1) and Cd₂(Beta)₃Cl(H₂O) (2) (Hbeta = 5-benzyl-tetrazole) have been synthesized by the in situ [3 + 2] cycloaddition reaction of 5-benzylacetonitrile, sodium azide and MCl₂ [M = Zn (1); M = Cd (2)] under hydrothermal condition. Complex 1 is a coordination polymer comprised of numerous mildly undulated two-dimensional (2D) layers with a (4, 4) topological network; while complex 2 is a 3D coordination framework constructed from the interconnection of various helical chains through cadmium–chlorine bridges. Furthermore, the luminescence properties of two complexes have been investigated.     

Electrochemical syntheses and structures of lead(II) and bismuth(III) complexes of 4-(trimethylammonio)benzenethiolate

Two main-group metal complexes of the zwitterionic ammonium thiolate complexes, [M(Tab)₃](ClO₄)_n (Tab = 4-(trimethylammonio)benzenethiolate) (1: M = Pb, n = 2; 2: M = Bi, n = 3), were prepared by electrochemical oxidation of Pb or Bi electrode in MeCN containing Tab and Et₄NClO₄. Each M atom in 1 and 2 is coordinated by three S atoms of three Tab ligands, forming a trigonal pyramidal coordination geometry. The resulting [M(Tab)₃]ⁿ⁺ cations are interconnected by secondary M⋯S interactions to form two different 1D cationic chains. The electrochemical properties of 1 and 2 were also investigated by cyclic voltammetry.     

Structure,electrochemistry and spectroscopy of a new diacylhydrazido-bridged diruthenium complex with a strongly near-infrared absorbing RuIIIRuII intermediate

Reaction of Ru(bpy)₂Cl₂·2 H₂O with 1,2-bis(trifluoroacetyl)hydrazine H₂(adc-CF₃) under basic conditions yields the dinuclear [(μ-adc-CF₃){Ru(bpy)₂}₂]²⁺ ion which was isolated and crystallized for structure determination in the meso diastereoisomer form as the bis(hexafluorophosphate). The Ru ··Ru distance was determined at 5.029(1) Å, and the N–N bond length at 1.463(5) Å reveals a hydrazido(2?) form of the bridge, implying unchanged + II metal oxidation states. Besides bpy-based reduction, the cyclic voltammetric analysis revealed two oxidation waves with a (3+) intermediate. Spectroelectrochemistry demonstrated that this intermediate [(μ-adc-CF₃){Ru(bpy)₂}₂]³⁺ with a comproportionation constant of K_c = 10^8.8 and an absorption at 1680 nm (ε = 9900 M^-1 cm^?1) is a mixed-valent species as evident most convincingly from the EPR parameters at g₁ = 2.239, g₂ = 2.065, g₃ = 1.891 (g_av = 2.101, Δg = g₁ ? g₃ = 0.348).     

Photocatalytic degradation of acetic acid on spinel ferrites MFe2O4 (M = Mg,Zn, and Cd)

Spinel ferrites MFe₂O₄(M = Mg, Zn, and Cd) with Fe(III) in a d⁵ electron configuration were prepared via a conventional solid-state reaction. The amount of CO₂ generated by the photocatalytic degradation of acetic acid on these ferrites was measured under irradiation by a xenon lamp with a power of 300 W. Photocatalytic degradation was observed for all the compounds, and the results revealed that MgFe₂O₄ exhibited the highest degradation, i.e., 196 μmol/g/h. The degradation in the presence of MFe₂O₄(M = Mg, Zn, and Cd) increased with increasing heating condition.     

Synthesis,crystal structure and photophysical properties of a novel Pt(II) complex with multi-functionalized cyclometalating ligand

A novel Pt(II) complex [(L)PtCl] (HL = 4-{p-[N-(4-(9-carbazole))butyl-N-phenyl] aniline}-6-phenyl-2,2′-bipyridine) has been synthesized and verified by ¹H NMR, elemental analysis and X-ray crystallography. The crystal (C₄₄H₃₅N₄ClPt, M_r = 850.30) belongs to monoclinic system, space group P2(1)/c, with a = 21.864(6), b = 9.306(3), c = 17.240(5) Å, β = 96.483(6)°, Z = 4, V = 3485.3(16) ų, D_C = 1.620 g/cm³, μ(Mo-Kα) = 4.141 mm^? 1, F(000) = 1688, R₁ = 0.0591, wR₂ = 0.0976. The coordinate geometry of the Pt atom is a distorted square planar configuration. The complex molecules are stacked by a weak π–π interaction in a head-to-tail fashion along the b axis to form 1D chain and the alternating 1D chains are packed to form the 2D lamellar system. The complex shows an intense metal-to-ligand charge transfer (¹MLCT) (dπ(Pt) → π*(L)) transitions (ε ～ 2 × 10⁴ dm³ mol^? 1 cm^? 1) at 448 nm in the UV–Vis absorption spectrum and a strong phosphorescence at 592 nm in CH₂Cl₂ solution at room temperature. An intramolecular energy transfer process from the carbazole unit to the arylamine-modified [(C^N^N)PtCl] emissive center exists in the complex.     

A donor–chromophore complex containing the polyazine bridging ligand 2,3-bis(2-pyridyl)pyrazine

The complex [(PTZpbpy)₂Ru(dpp)](PF₆)₂ coupling a phenothiazine derived electron donor to a ruthenium complex with a polyazine bridging ligand dpp (PTZpbpy = 4-methyl-4′-(4-(N-phenothiazinato)pentyl)-2,2′-bipyridine, dpp = 2,3-bis(2-pyridyl)pyrazine) has been synthesized and the redox, spectroscopic, and excited state properties elucidated. In the coupled electron donor system, the emission intensity from the Ru(dπ) → dpp(π¹) ³MLCT state is quenched by 94% of that of the analogous system [(bpy)₂Ru(dpp)](PF₆)₂ (bpy = 2,2′-bipyridine) which lacks a coupled electron donor. Coupling a donor–chromophore unit to a bridging ligand will allow the expansion of the molecular architecture to form complex molecular assemblies which contain covalently attached electron donors.     

Binuclear rhodium(III) and iridium(III) monoselenocarboxylates: Synthesis,spectroscopy and structure of an ortho-metallated iridium complex featuring an IrCCC(μ-Se) chelate ring

Monoselenocarboxylate–bridged binuclear complexes of Rh^III and Ir^III, [(Cp1MCl)₂(μ-SeCOAr)₂] (1) (M = Rh or Ir; Cp1 = pentamethylcyclopentadienyl; Ar = Ph, C₆H₄Me–4), have been isolated either by the reaction between [Cp1₂M₂(μ-Cl)₂Cl₂] with KSeCOAr in acetonitrile or by treatment of [Cp1MCl(solvent)₂][PF₆] with KSeCOAr in acetone. The novel binuclear complexes, [Cp1IrCl(μ-SeCOAr)(κ²-SeCOC₆H₃R–)IrCp1] (2) (R = H or Me-4) with ortho-metallation at one of the iridium centres have been isolated following the use of excess AgPF₆. The single crystal structure of [Cp1IrCl(μ-SeCOC₆H₅)(κ²-SeCOC₆H₄–)IrCp1] (2a) exhibits two phenylcarboselenolate moieties situated in syn fashion with respect to the “Ir₂Se₂” plane, one of which leans towards the metal centre in order to undergo ortho-metallation after iridium–chlorine bond dissociation.     

Synthesis,characterisation and cryomagnetic studies of a novel homonuclear Nd(III) Schiff base dimer

A novel homodinuclear complex [Nd^III(L)(NO₃)]₂ (1) has been synthesised [H₂L = N¹,N³- bis(salicylideneimino)diethylenetriamine, a pentadentate Schiff base with N₃O₂ donor set] and characterised with spectroscopic and micro-analytical techniques. Single crystal X-ray diffraction study reveals a centrosymmetric binuclear neutral entity [space group, P2₁/n; a = 12.911(5); b = 11.938(5); c = 13.960(5) Å; Z = 4] where Nd(III) metal centers are bridged together by two phenoxo oxygen atoms each coming from the two ligands. The most interesting fact is that two similar “salen” moieties of each ligand are behaving completely different in their coordination. In the doubly deprotonated ligand (L²⁻), one phenoxo oxygen is mono coordinated to the metal, whereas its immediate neighbour on the other end bridges the two Nd(III) centers. The distance between the Nd(III) centers is found to be 3.884(3) Å. Temperature dependence (2–300 K) magnetic susceptibility study suggests the presence of an antiferromagnetic interaction operating via two phenoxo bridges.     

Layered particle-based polymer composites for coatings: Part I. Evaluation of layered double hydroxides

Layered double hydroxides (LDH) suitable as fillers for the formulation of waterborne polyurethane (WPU) nanocomposites in coating applications are designed and characterized. Their elaboration follows a simple and reproducible process leading to samples without impurity. The attention is paid to the impact of the LDH nature (M_xAl/CO₃^2?, M = Mg and/or Zn, and x = 2, 3 and 4) on the structure characteristics, i.e. cell parameters and coherent domain dimensions. Focusing on two end-member phases M₂Al/CO₃^2?, M = Mg or Zn, the microstructural characterization performed from X-ray diffraction peak profile analyses permits to point out larger coherent domain sizes for Zn₂Al species than for Mg₂Al ones, and then to correlate with the “macroscopic” crystallinity of the samples. The evolution of LDH slurries over time is tentatively considered in a prediction interest. The stability of a chosen organic–inorganic hybrid, taken Mg₂Al as inorganic host structure with anions of the 4-aminobenzene sulfonic acid (4-ABSA), is studied as function of its carbonate contamination in time. Finally, the dispersion of LDH fillers in WPU is scrutinized in terms of WPU/LDH structure revealed by indirect and direct observations, XRD and TEM, respectively.     

A novel (μ-OAc)2 bridged unsymmetric coordinated binuclear Mn(II) macrocyclic complex with ligating pendant-arm

A novel binuclear manganese Mn(II) macrocyclic complex with two pyridylmethyl pendant arms, [Mn₂^II(H₂L)(μ-OAc)₂](ClO₄)₂ · H₂O, has been synthesized and characterized crystallographically and magnetically. The crystal structure of the complex shows that two manganese ions locate in the same head of the macrocycle, leaving an uncoordinating cavity to catch protons through oxide of phenolate and the nearby imine groups in another head. The electrochemical study demonstrates that the complex gives two couples of redox peaks with E_1/2 of 0.3775 V and 0.8409 V, respectively. The variable temperature magnetic susceptibility measurement on the sample displays weak antiferromagnetic interaction between two manganese (II) with the J = −3.733(7) cm⁻¹. This complex exhibits a moderate activity for catalyzing disproportionation of H₂O₂ to O₂.     

Self-assembly of an organo-palladium molecular basket that encapsulates cobalticarborane anion in water

Two [M₃L₃]^6 +-type organo-palladium(II) macrocyclic host molecules, {[(phen)Pd]₃(4,7-phen)₃}(NO₃)₆, 1·6NO₃⁻; {[(dtod-phen)Pd]₃(4,7-phen)₃}(NO₃)₆, 2·6NO₃⁻, (where M = (4,7-phen)Pd, (dtod-phen)Pd; 4,7-phen = 4,7-phenanthroline (L), phen = 1,10-phenanthroline, dtod-phen = 5,6-di(1′,4′,7′,10′-tetraoxododecanoxy)-1,10-phenanthroline), have been synthesized by metal-directed self-assembly in aqueous solution. These basket-shaped hosts bearing syn, syn, syn orientations and their anion complexes, have been fully characterized by ¹H NMR, cold-spray ionization mass spectrometry (CSI-MS) and in the case of basket-shaped host 1*PF₆⁻ by X-ray single-crystal diffraction analysis. On the basis of anion binding structure within the cavity of 1, the molecule basket 2 possessing a hydrophobic inner cavity expanded with hydrophilic polyethyleneglycol chains was successfully designed for encapsulating one giant anion [(C₂B₉H₁₁)₂Co]⁻ in water and the host–guest interaction was studied by ¹H NMR titration and CSI-MS.     

Effects of salicylate derivate on the competing reaction of chromium(III) complex [Cr(III)(R-SA)(en)2]Cl with apoovotransferrin

Four novel Cr(III) complexes, Bis(ethylenediamine-κ²N,N′)(R-SA-κ²O,O′)chromium(III) chloride (H₂SA = salicylic acid, R = 5-F, 5-Cl, 5-Br, 4-CH₃ ethylenediamine = en) have been synthesized and three of them are determined by X-ray crystallography. The competition reaction with EDTA and apoovotransferrin (apoOTf) was monitored by UV–Visible (UV–vis) and fluorescence spectra at 37 °C. The reaction with EDTA is only a simple competitive process and no specific selectivity was observed (k_EDTA/F410 = 4.07 × 10^?3–4.37 × 10^?3 M^?1 s^? 1). While for the reaction with apoOTf, an instable intermediate species (R-SA)–Cr(III)–OTf forms (k_OTf/F336 = 1.70 × 10^? 1–2.08 × 10^?1 M^?1 s^? 1), where R-SA^2? act as the role of synergistic anion. The intermediate is instable and the R-SA^2? ligand will then be released with the rate constants of 1.17 × 10^? 1 (5-F-SA^2?) ≈ 1.01 × 10^? 1 (4-CH₃-SA^2?) > 3.19 × 10^? 2 (5-Cl-SA^2?) > 3.25 × 10^? 3 (5-Br-SA^2?) M^?1 s^? 1. The substitutive groups R on SA have positive influence on charge density of O donor atom, which directly affect the stability of the (R-SA)–Cr(III)–OTf intermediate.     

Syntheses,crystal structures and properties of dinuclear hydrido-tris(3,5-diphenylpyrazol-1-yl)borate complexes with the S―S coupled and dimerized quinoxaline-2,3-dithiolate ligand

New dinuclear complexes with the bridging S―S coupled and dimerized quinoxaline-2,3-dithiolate (dsqdt) ligand, [Tp^Ph2M(dsqdt)MTp^Ph2] (Tp^Ph2 = hydro-tris(3,5-diphenylpyrazol-1-yl)borate; M = Co, 1; M = Ni, 2; M = Mn, 3), were prepared. X-ray crystal structure studies for complexes 1–3 indicate that the dsqdt ligand forms the unique κ²-coordinated mode through S and N atoms from the same qdt unit. The absorption spectra, redox behavior and magnetic properties of the compounds are reported.     

A novel transition-metal-linked hexaniobate cluster with photocatalytic H2 evolution activity

A novel transition-metal (TM) complex based on Lindqvist polyoxoniobate K₁₀[(Nb₆O₁₉)Cr^III(H₂O)₂]₂·28H₂O (1) has been synthesized by a new two-pot synthesis strategy and structurally characterized by single crystal X-ray diffraction analysis, IR spectrum, UV–vis spectroscopy, XRPD and TG analysis. Compound 1 crystallizes in the C2/m space group with a = 32.143(19) Å, b = 10.030(6) Å, c = 12.878(8) Å, β = 110.611(9)°, and V = 3886(4) ų. X-ray structure analysis reveals that polyanion [(Nb₆O₁₉)Cr^III(H₂O)₂]₂^10 − (1a) represents the first example of two nuclear dimeric polyoxoniobate, in which two Lindqvist anions [Nb₆O₁₉]⁸ are sandwiched by two {Cr^III(H₂O)₂} groups. Further, 1 exhibits photocatalytic H₂ evolution activity.     

Biodegradable latexes from animal-derived waste: Biosynthesis and characterization of mcl-PHA accumulated by Ps. citronellolis

Backgroundmcl-PHA biosynthesis by Pseudomonas citronellolis from tallow-based biodiesel as inexpensive carbon feed stock was accomplished. Fermentation protocols, kinetic analysis, an efficient product recovery strategy, and a detailed product characterization are presented.ResultsA maximum specific growth rate, μ_max. of 0.10 and 0.08 h^?1, respectively, was achieved in two different fermentation set-ups. Volumetric productivity for mcl-PHA amounted to 0.036 g/L h and 0.050 g/L h, final intracellular PHA contents calculated from the sum of active biomass and PHA to 20.1 and 26.6 wt.%, respectively. GC-FID analysis showed that the obtained biopolyester predominantly consists of 3-hydroxyoctanoate and 3-hydroxydecanoate, and, to a minor extent, 3-hydroxydodecanoate, 3-hydroxynonanoate, 3-hydroxyhexanoate, and 3-hydroxyheptanoate monomers. This was confirmed by ¹H- and ¹³C NMR, also evidencing the occurrence of low quantities of unsaturated and 3-hydroxyvalerate building blocks. High purity of the recovered materials was proofed by elemental analysis. Regarding the results from thermogravimetric analysis, differential scanning calorimetry and molecular mass determination, results were in a range typical for this type of PHA (1st fermentation: decomposition temperature T_d = 296 °C, peak of melting range T_m = 48.6 °C; glass transition temperature T_g = ?46.9 °C, degree of crystallinity X_c = 12.3%, M_w = 66,000, M_n = 35,000, dispersity index P_i = 1.9; 2nd fermentation: T_d = 295 °C, T_m = 53.6 °C, T_g = -43.5 °C, X_c = 10.4%, M_w = 78,000, M_n = 196,000, P_i = 2.5).     

An inclined interpenetrating heteropolynuclear polymer with unusual propagation of metal carboxylate secondary building units by both carboxylate and pyridyl bridging ligands

The objective of this paper is to describe an unusual coordination polymer, M₄(μ₄-O)(bipy)(m-BDC)₃ (sM₄ = Zn_2.36 Co_1.64, bipy = 4,4′-bipyridine, m-H₂BDC = 1,3-benzenedicarboxylic acid) (1), which has been hydrothermally synthesised and characterized by single-crystal X-ray diffraction, XRPD, IR, TGA, ICP, atomic absorption, and element analysis. 1 crystallizes in the P4₂/mnm space group and contains a M₄O(O₂C)₆ secondary building unit (SBU) with an inclined interpenetrated (4, 4) topology, and is a rare combination of the two most successful approaches to coordination polymer design: generation of metal carboxylate SBUs and the use of pyridyl donor bridges. Moreover, complex 1 exhibits intense fluorescence at about 424 nm (λ_ex = 312 nm) in the solid state.