Surface-enhanced Raman scattering of 4,4′-bipyridine on gold nanoparticle surfaces

The adsorption structure and mechanism of 4,4′-bipyridine (BiPy) on gold nanoparticle surfaces has been investigated by means of surface-enhanced Raman scattering (SERS). The aromatic ring of BiPy appeared to assume a perpendicular orientation with respect to the gold surface from the presence of the ν(CH) band at ∼3060 cm⁻¹. The SERS intensities of several vibrational modes of BiPy on Au were found to vary as the bulk concentration. The SERS intensities for BiPy on Au could be ascribed to both the electromagnetic (EM) and charge transfer (CT) enhancement mechanism.     

New complexes of heavy lanthanides with 4,4′-bipyridine and trichloroacetates

Novel mixed-ligand complexes with empirical formula Ln(4-bpy)₂(CCl₃COO)₃·nH₂O [where Ln(III)?=?Dy, Ho, Er, Tm, Yb, Lu; 4-bpy?=?4,4??-bipyridine] were prepared and characterized by chemical and elemental analysis, infrared spectroscopy, and conductivity measurements (in methanol, dimethylformamide, and dimethyl sulfoxide). X-ray powder diffraction patterns indicate that the complexes are small crystalline compounds. IR spectra of complexes show that all carboxylate groups and 4-bpy are engaged in coordination of lanthanide ions. The thermal behavior of complexes was studied by means of TG, DTG, DTA techniques in the solid state under nonisothermal conditions in air atmosphere. During heating, the complexes decompose via intermediate products to the oxide Ln₂O₃. The combined TG?CFTIR technique was employed to study the decomposition pathway of the Ho(III) and Tm(III) complexes in flowing argon atmosphere.     

Characterization and thermal kinetic studies on charge-transfer complexes of 4,4′-bipyridine with benzoquinone derivatives

4,4′-Bipyridine belong to an important class of compounds with wide applications in different fields and since the formation charge transfer compounds give opportunity to improve the physical and chemical properties of different donors so charge transfer compounds of 4,4′-bipyridine (Bpy) with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone [chloranilic acid] (CHA) and 2,3,5,6-tetrachloro-1,4-benzoquinone [choloranil] (CHL) were studied. The stoichiometries of the reactions were determined from photometric titration methods. Although the thermodynamic parameters [Gibbs free energy (ΔG°), enthalpy (ΔH°), and entropy change (ΔS°)] were calculated. The thermal decomposition of the complexes follows first order kinetics and thermodynamic parameters of the decomposition were calculated. The structural morphology was investigated by scanning electron microscopy (SEM) and Transmission Electron Microscopy (TEM) and show that these molecules are of nanosize.     

Adsorption and redox chemistry of cis-RuLL'(SCN)2 with L=4,4′-dicarboxylic acid-2,2′-bipyridine and L'=4,4′-dinonyl-2,2′-bipyridine (Z907) at FTO and TiO2 electrode surfaces

The electrochemical and spectroelectrochemical properties of the sensitizer dye Z907 (cis-RuLL'(SCN)₂ with L=4,4′-dicarboxylic acid-2,2′-bipyridine and L'=4,4′-dinonyl-2,2′-bipyridine) adsorbed on fluorine-doped tin oxide (FTO) and TiO₂ surfaces have been investigated. Langmuirian binding constants for FTO and TiO₂ are estimated to be 3 × 10⁶ M⁻¹ and 4 × 10⁴ M⁻¹, respectively. The Ru(III/II) redox process is monitored by voltammetry and by spectroelectrochemistry. For Z907 adsorbed onto FTO, a slow EC-type electrochemical reaction is observed with a chemical rate constant of ca. k = 10⁻² s⁻¹ leading to Z907 dye degradation of a fraction of the FTO-adsorbed dye. The Z907 adsorption conditions affect the degradation process. No significant degradation was observed for TiO₂-adsorbed dye. Degradation of the Z907 dye affects the electron hopping conduction at the FTO–TiO₂ interface.     

Investigation on structure and thermal behavior of 4,4′-dihydroxyazobenzene functionalized with epoxy groups

A new symmetric compound with azobenzene chromophore and epoxide groups, namely diglycidyl ether of 4,4′-dihydroxyazobenzene (DGEAB) was obtained and characterized. Its thermal behavior was monitored taking into account that many reactions of epoxides are carried out under heating. DGEAB was found to be stable up to 200 °C, but at higher temperature, its decomposition involves three step of degradation with the formation of an appreciable quantity of the char.     

Synthesis and some properties of light lanthanide complexes with 4,4′-bipyridine and dibromoacetates

In this study, new complexes with formulae: Ce(4-bpy)(CHBr₂COO)₃·H₂O, Ln(4-bpy)_0.5(CHBr₂COO)₃·2H₂O (where Ln(III) = Pr, Nd, Sm; 4-bpy = 4,4′-bipyridine) and Eu(4-bpy)(CHBr₂COO)₃·2H₂O were prepared, and characterized by chemical and elemental analyses, and IR spectroscopy. The way of metal–ligand coordination was discussed. They are small crystalline. The complexes of Pr(III), Nd(III), and Sm(III) are isostructural in group. Conductivity studies (in methanol, dimethylformamide, and dimethylsulfoxide) were also performed and described. The thermal properties of complexes in the solid state were studied using TG–DTG techniques under dynamic flow of air atmosphere. TG–MS system was used to analyze principal volatile thermal decomposition and fragmentation products evolved during pyrolyses of Ce(III) and Sm(III) complexes in dynamic flow of air atmosphere.     

Structural characterization of copper (II) tetradecanoate with 2,2′-bipyridine and 4,4′-bipyridine to study magnetic properties

This paper presents synthesis, structural characterization and spintronic applications of copper (II) tetradecanoate derived magnetic complexes. The complexes were prepared by a chemical reaction between [Cu₂(CH₃(CH₂)₁₂COO)₄](EtOH)₂ and 2,2′-bipyridine-4,4′-bipyridine ligands respectively. The complexes were further reacted between the product of the first reaction and 4,4′-bipyridine-2,2′-bipyridine respectively. The structural characterization techniques included elemental analysis, Fourier transformed infrared spectroscopy (FTIR), Ultra-violet–Visible (UV–Vis) spectroscopy, polarized optical microscopy, magnetic moment and thermogravimetric analysis. The structural and characterization results suggested that the synthesized complexes were binuclear and mononuclear covalent complexes of copper(II) with structural formulas [Cu₂(η²-(OOCR)₄](4,4′-bpy)2H₂O] and [Cu(η¹-(OOCR)₂(2,2′-bpy) (4,4′-bpy)] respectively.     

Two supramolecular structures constructed from Keggin-type polyoxometalates and 4,4′-bipyridine

Two supramolecular compounds based on Keggin-type polyoxometalates (POMs), (4,4′-H₂bpy)(4,4′-Hbpy)[PMo₁₂O₄₀] (1) and (4,4′-H₂bpy)(4,4′-Hbpy)₂[SiW₁₂O₄₀]?·?4H₂O (2), have been synthesized hydrothermally and characterized by elemental analyses, IR, UV-Vis, XPS spectra, thermogravimetric analyses, and single-crystal X-ray diffraction analyses. The two compounds consist of 4,4′-bipyridine (4,4′-bpy) ligands and different Keggin-type POMs which are [PMo₁₂O₄₀]^3? for 1 and [SiW₁₂O₄₀]^4? for 2. There are hydrogen-bonding interactions between the POMs, 4,4′-bipyridine, and/or water in 1 and 2. In addition, 2 contains an uncommon (H₂O)₂ water cluster.     

Networks based on aromatic glycidylamines: 1. Effect of curing conditions on the crosslinking of N,N-diglycidylaniline with 4,4′-diaminodiphenylmethane and of N,N,N′,N′-tetraglycidyl-4,4′-diaminodiphenylmethane with 4,4′-diaminodiphenylmethane

The effect of time and temperature of curing on the conversion of epoxy groups, on the relative change of some other functional groups (–OH, –NH₂, RNH), glass transition temperatureT _g , and equilibrium modulusG _e was investigated for epoxy networks having various initial ratios of N,N-diglycidylaniline to 4,4-diaminodiphenylmethane (DDM) and of networks with various ratio of N,N,N,N-tetraglycidyl-4,4-diaminodiphenylmethane and DDM. Curing conditions were found under which the conversion of minority groups is maximal at the minimal extent of degradation reactions for networks prepared both in the excess of amine and in the excess of epoxide. For networks prepared in the excess of epoxide the degree of the etherification reaction was found to depend on time and temperature.     

Syntheses and structures of copper benzene-1,4-dioxydiacetate complexes with 4,4′-bipyridine and 1,10-phenanthroline

Two new copper complexes, [Cu₂(BDOA)(4,4′-bpy)₂] ? 2H₂O (1) and [Cu(BDOA)(phen)] (2) (H₂BDOA = benzene-1,4-dioxydiacetic acid; 4,4′-bpy = 4,4′-bipyridine; phen = 1,10-phenanthroline), were synthesized and characterized by IR, elemental analysis, and single-crystal X-ray diffraction. Complex 1 exhibits a 2-D three-connected network structure with 6³ topology. Complex 2 displays a 1-D chain structure. Furthermore, the 3-D supramolecular networks of 1 and 2 are constructed via rich hydrogen bonds. Thermal stability of 1 is discussed in this article.     

Coordination behaviour and thermolysis of some rare-earth complexes with 4,4′-bipyridine and di- or trichloroacetates

A novel mixed-ligand complexes with empirical formulae: Dy(4-bpy)(CCl₂HCOO)₃ · H₂O and Ln(4-bpy)_1.5(CCl₃COO)₃ · 2H₂O (where Ln(III) = Ce, Nd) were prepared and characterized by chemical and elemental analysis and IR spectroscopy, conductivity (in methanol, dimethyloformamide and dimethylsulfoxide). Analysis of the diffractograms showed that the obtained complexes are crystalline. Way of metal-ligand coordination discussed. The thermal properties of complexes in the solid state were studied under non-isothermal conditions in air atmosphere. During heating the complexes decompose via intermediate products to the oxides: Ln₂O₃ (Nd, Dy) and CeO₂. TG-MS system was used to analyse principal volatile thermal decomposition and fragmentation products evolved during pyrolysis of Dy(4-bpy)(CCl₂HCOO)₃ · H₂O in air.     

Synthesis and crystal structure of polymeric 4,4′-bipyridine cadmium(II) sulfate trihydrate

Polymeric 4,4′-bipyridinecadmium(II) sulfate trihydrate, [C₁₀H₈CdN₂O₇S] _n , has been synthesized and characterized by X-ray diffraction and spectroscopic methods. The compound crystallizes in space group P6₅22, with a?=?11.4465(15)?Å, c?=?20.7380(18)?Å. The coordination geometry around cadmium is distorted octahedral with Cd–N2?=?2.311(9), Cd–O1W?=?2.278(8) and Cd–O(SO₄)?=?2.247(7)?Å.     

CdII 4,4,4-trifluoro-1-phenyl-1,3-butandione complexes of 1,10-phenanthroline and 4,4′-bipyridine

Cadmium(II) 4,4,4-trifluoro-1-phenyl-1,3-butandione (HTFPB) complexes of 1,10-phenanthroline (phen) and 4,4′-bipyridine (4,4′-bipy), Cd(L)(TFPB)₂, have been synthesized and characterized by elemental analysis, IR-, ¹H NMR spectroscopy and X-ray crystallography. The self-assembly of Cd(L)(TFPB)₂ complexes, (L?=?phen or 4,4′-bipy) is caused by C–H?···?F–C, and π–π stacking interactions.     

Syntheses and Crystal Structures of 4,4′Diformyl-diphenoxyethane and 4,4′4′′-Triformyl-triphenoxytriethylamine

1 INTRODUCTION With the methods of [2+3] and [1+1] tripodal condensation of polyaldehyde with polyamine, many Schiff bases and their relative reduced polyaza cryptands have been facilely synthesized in high yields[1～5]. In this one-step route, some metal ions such as alkali[2, 6, 7], alkali earth[8], rare earth[9, 10] and other transition ions[4, 11, 12] were used as templates[13, 14]. Formerly, the dialdehydes are needed to be rigid structures[15] to prevent themselves from polymeri…     

Two 3-D CdII/ZnII complexes based on mixed 1,1-cyclobutanedicarboxylate and 4,4′-bipyridine ligands

Two new 3-D complexes, [M(L)(4bpy)_0.5(H₂O)]_∞ [M = Cd (1) and = Zn (2)], based on mixed 1,1-cyclobutanedicarboxylic acid (H₂L) and 4,4′-bipyridine (4bpy) have been synthesized; 1 and 2 feature (3,4)-connected (6³)(6⁵.8) topological networks consisting of pillared 2-D [M(L)(H₂O)]_∞ layered motifs. Complexes 1 and 2 are photoluminescent materials.     

Adsorption of thorium(IV) from aqueous solutions by poly(cyclotriphosphazene-co-4,4′-diaminodiphenyl ether) microspheres

Journal of Radioanalytical and Nuclear Chemistry - Poly(cyclotriphosphazene-co-4,4′-diaminodiphenyl ether) microspheres (PZA) was based on hexachlorocyclotriphosphazene (HCCP) and...     

Improvement of synthesis conditions of dispersed polymetallic Fe–Al–Mo systems in aqueous solutions

Kinetic dependences describing the processes occurring on aluminum microparticles in aqueous solutions containing iron and molybdenum ions were determined. It was shown that the samples obtained contain iron, molybdenum, and aluminum in the elementary state in the absence of an oxide phase.