Selectivity in metal ions mediated C–N bond formation reactions of 8‐aminoquinoline derivatives

Cyclisation reactions via C–N bond formation of 2‐bromo‐N‐(quinolin‐8‐yl)propanamide (I) and 2‐bromo‐N‐(quinolin‐8‐yl)acetamide (II) are facilitated by metal salts such as copper (+2), nickel (+2) perchlorate or nitrate and palladium (+2) acetate. Nickel (+2) perchlorate mediated reaction of I and II resulted in C–N bond formation to give corresponding perchlorate salts of three fused six‐membered heterocyclic rings. The copper (+2) mediated reactions are found to be solvent dependent for I, but independent for II. Copper mediated reaction of II gave cyclised product analogous to the one obtained from reaction of II with nickel (+2) perchlorate in methanol or ethanol. But the reaction of I with copper (+2) perchlorate in methanol gave C–N bonded methoxylated cyclised product. This reaction took place in two steps, cyclisation followed by methoxylation. The source of methoxy group is confirmed to be from methanol by deuterium labelling experiments. Whereas similar copper mediated reaction of I in ethanol led to nucleophilic substitution of bromide ion by ethoxide. The structures of the salts of fused heterocyclic compounds were determined and their fluorescence emissions were studied. The large difference in fluorescence emission of compound V formed from copper mediated reaction in ethanol from the compound VI formed from nickel mediated reaction in methanol or ethanol, this feature can be used to distinguish nickel (+2) and copper (+2) ions. The reaction of II with palladium (+2) acetate resulted in the formation of C–N bond to yield the corresponding heterocycle as bromide salt; without anion exchange. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis,structures and near-infrared luminescence properties of Ho and Yb coordination complexes

Four Ln³⁺ coordination complexes with the formulas [Ln(p-toluylate)₂(Ac)(H₂O)]_n (Ln=Ho 1, Yb 2) and {[Ln₂(OOCCH₂CH₂COO)₃(H₂O)₄]·6H₂O}_n (Ln=Ho 3, Yb 4) were synthesized hydrothermally. Their structures were determined by single-crystal X-ray diffraction. Complexes 1 and 2 are isomorphic and form infinite 2D network structures comprising p-toluylate and acetate (Ac^–) moieties. Complexes 3 and 4 are also isomorphic and possess infinite 2D structures in which succinate acts as bridging ligands that are connected to a 3D hydrogen bonding network by O–H…O hydrogen bonds. Solid-state IR and UV-Vis-NIR spectra, excitation and emission spectra were determined for the four complexes at room temperature. Complexes 1 and 2 exhibit characteristic NIR emission bands of Ln³⁺ ions but these are shifted and split relative to the theoretical positions. This is also evident for their UV-Vis-NIR spectra. The influence of ligands on enhancing the NIR luminescence of Ln³⁺ ions in complexes is discussed.     

Photoluminescence spectroscopy study on tris(8-hydroxyquinoline) aluminum film

In situ photoluminescence spectroscopy (PL) measurements of tris(8-hydroxyquinoline) aluminum (Alq₃) film were carried out. Upon deposition of Alq₃ on the glass substrate, the PL intensity changes dramatically, while the peak position of Alq₃ emission shows a sharp red-shift from 524 nm at the initial deposition of Alq₃, and tends to a saturation value of 536 nm for the film thickness range from 2 to 500 nm. This red-shift is associated with the change from the 2D to 3D exciton state with increasing Alq₃ film thickness. Temperature dependent PL spectra of Alq₃ films showed, besides the changes in the PL intensity, clearly a blue-shift of Alq₃ emission about 9 nm for the film annealing up to 150 °C, while no any shift of Alq₃ emission was observed for the film annealing below 130 °C. Both changes in PL intensity, and especially in the peak position of Alq₃ emission were attributed to crystallization (thermal) effect of Alq₃ film upon annealing.     

Copper-assisted shape control in colloidal synthesis of indium oxide nanoparticles

Indium oxide is an important n-type transparent semiconductor, finding application in solar cells, sensors, and optoelectronic devices. We present here a novel non-injection synthesis route for the preparation of colloidal indium oxide nanocrystals by using oleylamine (OLA) as ligand and as solvent. Indium oxide with cubic crystallographic structure is formed in a reaction between indium acetate and OLA, the latter is converted to oleylamide during the synthesis. The shape of the nanocrystals can be influenced by the addition of copper ions. When only indium (III) acetate is used as precursor flower-shaped indium oxide nanoparticles are obtained. Addition of copper salts such as copper (I) acetate, copper (II) acetate, copper (II) acetylacetonate, or copper (I) chloride, under otherwise identical reaction conditions changes the shape of nanoparticles to quasi-spherical or elongated. The anions, except for chloride, do not influence the shape of the resulting nanocrystals. This finding suggests that adsorption of copper ions on the In₂O₃ surface during the nanoparticles growth is responsible for shape control, whereas changes in the reactivity of the In cations caused by the presence of different anions play a secondary role. X-ray diffraction, transmission electron microscopy, nuclear magnetic resonance, energy dispersive X-ray analysis, and UV–Vis-absorption spectroscopy are used to characterize the samples.     

ESR spectral studies of a Cu(II) salicylidene tyrosine complex

A novel Schiff base derived from salicylidene and tyrosine and its copper(II) complex have been synthesized and characterized. The composition of the complex is K[CuL(Ac)] · H₂O, where L = H₁₃C₁₆NO₄. Electron spin resonance (ESR) spectra of the copper(II) complex were investigated at different temperatures and in various solvents. The second-order effect and the relaxation effect were observed in the solution spectrum at room temperature and satisfactorily explained by the spin Hamiltonian. The bonding parameters of the Cu(II) complex were calculated with spectral parameters from ESR spectra at low temperature. Its bonding characterization and stability were discussed. The result shows that both the in-plane σ-bond and the in-plane π-bond in the complex play an important role.     

Preparation and fluorescent sensing applications of novel CdSe-chitosan hybrid films

A novel CdSe-chitosan hybrid fluorescent film has been fabricated by dipping a chitosan film containing Cd(Ac)₂ into NaHSe aqueous solution under a nitrogen atmosphere at room temperature. It has been demonstrated that utilization of a chitosan film as a substrate prohibits the aggregation of the as formed CdSe micro-nano-particles, and enhances the sensing performance of the inorganic-organic hybrid film. It has been also revealed that the amount of CdSe embedded in the hybrid film can be altered by varying the initial concentration of Cd(Ac)₂. Importantly, the photoluminescence emission of the hybrid film is selectively sensitive to the presence of polyamines. Furthermore, the response is reversible. Accordingly, it is anticipated that the film may be developed into a polyamine sensor.     

Electrochemical and thermal properties of hyperbranched polymer electrolytes for batteries

Terminal-acetylated hyperbranched poly(ethylene glycol) derivatives containing diethylene, triethylene, and hexaethylene and 3,5-dioxybenzoate branching units (poly-Ac1a, poly-Ac1b, and poly-Ac1c) were synthesized. Electrochemical and thermal properties of the hyperbranched polymer electrolytes with lithium salts such as LiCF₃SO₃ and LiN(CF₃SO₂)₂, the composite hyperbranched polymer electrolytes with LiN(CF₃SO₂)₂ containing α-LiAlO₂ and γ-LiAlO₂ fillers, and the hyperbranched polymer blended poly(ethylene oxide) electrolytes with LiN(CF₃SO₂)₂ were investigated and discussed. Paper presented at the 8th EuroConference on Ionics, Carvoeire, Algarve, Portugal, Sept. 16–22, 2001.     

Unusual EPR Spectra with Inverse Axial g values of Chlorosalicylate–Cu(II)–2,6-Pyridinedimethanol Complex in Frozen Water–Methanol Solution

Copper(II) complex systems containing 3,5-di, 4-, or 5-chlorosalicylic acids (X-ClsalH) and different copper(II) salts (copper acetate (Cu(ac)₂) or copper sulphate (CuSO₄)), with varying 2,6-pyridinedimethanol (pydime) concentration, [Cu(ac)₂(aq) or CuSO₄(aq) + 2 (X-ClsalH(solv)) + x pydime(solv)], where X = 3,5-di, 4-, or 5- and x = 0, 1, 2, 4, or 8, were prepared. The effects of two copper(II) salts (containing anions of different basicity) and N-donor ligand (pydime) with varying ligand-to-metal ratio (x) on the formation of resulting complexes were studied by electron paramagnetic resonance (EPR) spectroscopy in frozen water/methanol (1:3 v/v) solutions. For x ≥ 2, unusual Cu(II) EPR spectra with "inverse" axial g values of (g _⊥ > g _∥ > 2.0023) were observed, which can indicate the compressed octahedral geometry of the central copper atom with the unpaired electron/hole localized on the $ d_{{z^{2} }} $ orbital. However, for x = 1, composite Cu(II) EPR spectra with both "usual" and "inverse" axial g values were detected. Finally, for x = 0 (ligand not present) Cu(II) EPR spectra only with the ‘usual’ axial g values of g _∥ > g _⊥ > 2.0023 were collected, which can indicate the elongated octahedral geometry of the central copper atom with the unpaired electron/hole localized on $ d_{{x^{2} - y^{2} }} $ orbital. The above described observations are independent of the usage of different copper(II) salts and X-chlorosalicylic acids.     

Radiation-induced decomposition of the metal-organic molecule Bis(4-cyano-2,2,6,6-tetramethyl-3,5-heptanedionato)copper(II)

The effects of vacuum ultraviolet radiation on the adsorbed copper center molecule bis(4-cyano-2,2,6,6-tetramethyl-3,5-heptanedionato)copper(II) (or Cu(CNdpm)₂), (C₂₄H₃₆N₂O₄Cu, Cu(II)) was studied by photoemission spectroscopy. Changes in the ultraviolet photoemission spectra (UPS) of Cu(CNdpm)₂, adsorbed on Co(1 1 1), indicate that the ultraviolet radiation leads to decomposition of Cu(CNdpm)₂ and this decomposition is initially dominated by loss of peripheral hydrogen.     

The synthesis of Ag/polypyrrole coaxial nanocables via ion adsorption method using different oxidants

Ag/polypyrrole (PPy) coaxial nanocables (NCs) were synthesized by an ion adsorption method. In this method, the pre-made Ag nanowires (NWs) were dispersed in the aqueous solution of copper acetate (Cu(Ac)₂), and the Cu²⁺ ions adsorbed onto the surface of Ag NWs can oxidize pyrrole monomers to polymerize into uniform PPy sheath outside Ag NWs after the Cu(Ac)₂-treated Ag NWs were re-dispersed in the aqueous solution of pyrrole. The morphology of NCs was characterized by transmission electron microscope (TEM) and scanning electron microscope (SEM). The relationship between the thickness of polymer sheath and the concentration of Cu(Ac)₂ was established. As Cu(Ac)₂ which served as the oxidant can also be replaced by AgNO₃ in this synthesis, the differences on the structure of polymer sheath caused by different oxidants were studied by surface-enhanced Raman scattering (SERS), high-resolution transmission electron microscope (HR-TEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). Comparing with the characterization results of Ag/PPy NCs synthesized using AgNO₃ as the oxidant which indicates the random arrangement of PPy chains at the interface between polymer sheath and Ag NWs, PPy chain oxidized by Cu²⁺ tends to show a relatively ordered conformation at the interface with the pyrrole rings identically taking the plane vertical to the surface of Ag NWs. In addition, although the main part of the polymer sheath was composed of PPy whatever kind of oxidant was used, the sheath of the NCs oxidized by Cu²⁺ is typical for the existence of Cu(I)–pyrrole coordinate structures with strong Cu(I)–N bond signal shown in XPS characterization.     

Evolution of the zinc compound nanostructures in zinc acetate single-source solution

A series of nanostructured zinc compounds with different nanostructures such as nanobelts, flake-like, flower-like, and twinning crystals was synthesized using zinc acetate (Zn(Ac)₂) as a single-source. The evolution of the zinc compounds from layered basic zinc acetate (LBZA) to bilayered basic zinc acetate (BLBZA) and twinned ZnO nano/microcrystal was studied. The low-angle X-ray diffraction spectra indicate the layered spacing is 1.34 and 2.1 nm for LBZA and BLBZA, respectively. The Fourier transform infrared (FTIR) spectra results confirmed that the bonding force of acetate anion with zinc cations decreases with the phase transformation from Zn(Ac)₂ to BLBZA, and finally to LBZA. The OH⁻ groups gradually replaced the acetate groups coordinated to the matrix zinc cation, and the acetate groups were released completely. Finally, the Zn(OH)₂ and ZnO were formed at high temperature. The conversion process from Zn(Ac)₂ to ZnO with release of acetate anions can be described as Zn(Ac)₂ → BLBZA → LBZA → Zn(OH)₂ → ZnO.     

Photosensitive YBCO gel film and its patterning by sol-gel process

The YBCO precursor solution was prepared using yttrium acetate, barium acetate and copper acetate as starting material, diethylenetriamine, trifluoroacetate, acrylic acid (AA) as chemical additives, methanol as solvent. The precursor solution was modified by AA, in which the Cu²⁺ of Cu(OAc)₂ and AA were reacted to form the photosensitive copper complex. The coated gel film using this precursor solution exhibited the photosensitivity to UV light at around 245 nm. Utilizing the photosensitivity, the patterned YBCO film with a high critical transition temperature (Tc) of 91.5 K was fabricated.     

Use of some Inorganic and Organic Compounds as Decontaminants for Cobalt-60 and Caesium-134 by Clover Plant Grown on Inshas Sandy Soil

Outdoor lysimeter experiments were carried out to elucidate the effect of 4 inorganic and 3 organic salts on ⁶⁰Co and ¹³⁴Cs uptake and dry matter yield of three cuts of clover in the soils of Inshas. A new concept was proposed for assessing the difference in capacity of soil to supply radionuclides to plants as affected by applied inorganic or organic compounds. A relation of plant tissue radionuclide content with time can be expressed in an exponential equation with corresponding regression coefficients. When the same plant species is grown on the same soil differing only in the applied compounds (e.g. Fe-EDDHA, Fe-DTPA, Fe-OAC, Fe(COO)₂, Al(OH)₃, Ca(H₂PO₄)₂, Fe₂O₃) the derived equation will change. Differences of either Co or Cs accumulation with time between control and any other treatment were evaluated. The data also show that Fe-DTPA is preferred for ⁶⁰Co as enhancing compound for plant uptake (for decontamination use), compared with other applied salts, on the other hand, any tested salts did not significantly effect ¹³⁴Cs taken by clover. It was also found that more than 70% of the total cobalt uptake was accumulated in the roots which indicate that Co is less mobile in plants than Cs.     

Effect of Pendant Group Length Upon Metal Ion Complexation in Acetonitrile by Di-Ionized Calix[4]Arenes Bearing Two Dansyl Fluorophores

A series of three di-ionizable calix[4]arenes with two pendant dansyl (1-dimethylaminonaphthalene-5-sulfonyl) groups linked to the lower rims was synthesized. Structures of the three ligands were identical except for the length of the spacers which connected the two dansyl groups to the calix[4]arene scaffold. Following conversion of the ligands into their di-ionized di(tetramethylammonium) salts, absorption and emission spectrophotometry were utilized to probe the influence of metal cation (Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Ag⁺, Cd²⁺, Co²⁺, Fe²⁺, Hg²⁺, Mn²⁺, Pb²⁺, Zn²⁺ and Fe³⁺) complexation in acetonitrile. Upon complexation with these metal cations, emission spectra underwent marked red shifts and quenching of the dansyl group fluorescence for the di-ionized ligand with the shortest spacer. A similar effect was noted for the di-ionized ligand with an intermediate spacer for all of the metal ions, except Ba²⁺. For the di-ionized ligand with the longest spacer, the metal cations showed different effects on the emission spectrum. Li⁺, Mg²⁺, Ca²⁺ and Ba²⁺ caused enhancement of emission intensity with a red shift. Other metal cations produce quenching with red shifts in the emission spectra. Transition metal cations interacted strongly with all three di-ionized ligands. In particular, Fe³⁺ and Hg²⁺ caused greater than 99% quenching of the dansyl fluorescence in the di-ionized ligands.     

Fabrication and performance evaluation of ultraviolet photodetector based on organic /inorganic heterojunction

Organic/inorganic ultraviolet photodetector was fabricated using thermal evaporation technique. Organic/inorganic heterojunction based on thermally evaporated copper (II) acetylacetonate thin film of thickness 200 nm deposited on an n-type silicon substrate is introduced. I–V characteristics of the fabricated heterojunction were investigated under UV illumination of intensity 65 mW/cm². The diode parameters such as ideality factor, n, barrier height, Φ_B, and reverse saturation current, I_s, were determined using thermionic emission theory. The series resistance of the fabricated diode was determined using modified Nord's method. The estimated values of series resistance and barrier height of the diode were about 0.33 KΩ and 0.72 eV, respectively. The fabricated photodetector exhibited a responsivity and specific detectivity about 9 mA/W and 4.6 × 10⁹ Jones, respectively. The response behavior of the fabricated photodetector was analyzed through ON-OFF switching behavior. The estimated values of rise and fall time of the present architecture under UV illumination were about 199 ms and 154 ms, respectively. Finally, enhancing the photoresponsivity of the fabricated photodetector, post-deposition plasma treatment process was employed. A remarkable modification of the device performance was noticed as a result of plasma treatment. These modifications are representative in a decrease of series resistance and an increase of photoresponsivity and specific detectivity. The process of plasma treatment achieved an increment of external quantum efficiency from 5.53% to 8.34% at −3.5 V under UV illumination.     

Improvement of Field Emission Characteristics of Copper Nitride Films with Increasing Copper Content

A copper nitride （Cu3N） thin film is deposited on a Si substrate by the reactive magnetron sputtering method. The XPS measurements of the composite film indicate that the Cu content in the film is increased to 80.82 at. % and the value of the Cu/N ratio to 4.2：1 by introducing 4% 112 into the reactive gas. X-ray diffraction measurements show that the film is composed of Cu3N crystallites with an anti-ReO3 structure. The effects of the increase of copper content on the field emission characteristics of the Cu3N thin film are investigated. Significant improvement in emission current density and emission repeatability could be attributed to the geometric field enhancement, caused by numerous surface nanotips, and the decrease of resistivity of the film.     

Efficient field emission from well-oriented Cu2O film

Well-oriented Cu₂O films comprising of octahedral-shaped crystals were grown directly on copper foil via an hydrothermal treatment. The well-oriented films were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Field emission from the film showed good emission properties, and, the electron emission turn-on field (E_to) and threshold field (E_thr) are about 9.6 and 13.4 V/μm respectively, which is similar to the values reported for CuO nanofiber, although the latter has a much larger size. The corresponding Fowler-Nordheim (F-N) plots showed a linear behavior. The sharp corners of the tips are considered as main electron emitters and account for its good performance.     

pH-dependent kinetics of MgCl2 adsorption under a fatty-acid Langmuir film

The effect of subphase pH (5.5 and 10.5) on the structure of behenic-acid monolayers was investigated during Mg²⁺ adsorption by means of Grazing Incidence X-ray Diffraction (GIXD) and Brewster Angle Microscopy (BAM). The final phase corresponding to an ion superlattice commensurate to the behenic-acid cell is pH-independent. In contrast, the sequence of phases evidenced from the initial L₂-phase to this final state presents at pH 10.5 an additional stage associated to a film condensation toward the L' ₂-phase. The structures of the intermediate states preceding the superstructure nucleation are slightly different, both with a short-range fatty-acid order. Finally, a laser light effect that could result from visible light absorption by the inorganic complexes is evidenced in the final state as well as in the intermediate phases.     

Synthesis and Spectral Study of Several Solid M3[Eu(2,6-Pyridinedicarboxylate)3] Salts (M=Li+, Na+, K+, Rb+, Cs+, NH4 +, and Pyridinium+)

Abstract

Salts of the [Eu(2,6-pyridinedicarboxylate)₃]^3- complex anion and various monovalent inorganic and organic counterions (Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, NH₄ ⁺, and pyridinium⁺) have been synthesized and studied by emission spectroscopy. The Eu³⁺ ion emission spectra exhibited by these salts have been observed with high resolution (less than 1.0 cm^?1) and at low temperature (77 K). The emission spectra of these compounds indicate that changing the attached counterion does not affect the site symmetry observed by the europium ion beyond slight distortions indicated by small shifts in the energies of the Eu³⁺ electronic levels.     

A facile route for rapid synthesis of cubic mesoporous silica

Ordered SBA-16-type mesoporous silica materials (MSMs) have been rapidly synthesized under weak acidic media in the presence of phosphomolybdic acid (abbreviated to HPMo) and inorganic salts (NaCl, Na₂SO₄, KCl and K₂SO₄) by using nonionic triblock copolymer F127 as a structure directing agent and tetraethylorthosilicate (TEOS) as a silica source. Both HPMo and inorganic salts play a crucial role in promoting SBA-16-type MSMs formation, and the reaction products have still retained an ordered body-centered cubic (Im3m) mesostructure after treated with 100 °C water for 120 h. The high hydrothermal stability of reaction products might be attributed to the higher degree of polymerization and condensation of silanol groups, arisen from the synergistic effect of rapid nucleation with the aid of HPMo and salt effect during the crystallization process.