Tetrathiafulvalene. XVIII. Elektronen-Donator-Akzeptor-Komplexe von Tetrathiafulvalenen (TTF) mit Tetracyanochinodimethan (TCNQ)

Tetrathiafulvalenes. XVIII. Charge-Transfer-Complexes of Tetrathiafulvalenes (TTF) with Tetracyanoquinodimethane (TCNQ) TTF form CT-complexes with TCNQ in solvents having small E_T-values, whose association constants are estimated. The energy of the absorption maximum of the CT-complex between octamethylentetrathiafulvalene and TCNQ increases linearly with decreasing E_T-values of the solvents. In chloroform the energy of the absorption maximum of the CT-complexes between TCNQ and tetrathiafulvalenes increases linearly with the oxidation potential of the tetrathiafulvalene.     

Tetrathiafulvalene. XXIV. Gewinnung von cis- und trans- Isomeren bei Tetrathiafulvalenen (TTF)

Tetrathiafulvalenes. XXIV. Isolation of cis- and trans-Isomers of Tetrathiafulvalenes (TTF) The synthesis of naphthylsubstituted TTF permits in the case of the α-naphthyl-methylsubstituted TTF the isolation of the cis- and trans-isomer by reason of differences in the solubility. The spectroscopical and electrochemical properties of naphthylsubstituted TTF are described.     

Tetrathiafulvalene. XXV [1]. Konjugativ verknüpfte polymere Tetrathiafulvalene (TTF)

Tetrathiafulvalenes. XXV. Conjugative Connected Polymeric Tetrathiafulvalenes (TTF) Syntheses and properties of a conjugative connected polymeric TTF (by tetrahydroanthracene units) and phenylene-bridged polymeric TTF are described. These polymers react with bromine, iodine or tetracyanoquinodimethane and form the radical cation salts, whose electrical conductivity is determined. The conjugatively connected polymeric radical cation salts show a higher conductivity than the twisted phenylene-bridged polymeric radical cation salts.     

Electrical and Spectroscopic Properties of TTF and TSF Salts with Tetrahalogenozinc(II) and -cadmium(II) Anions

Several tetrathiafulvalene (TTF) and tetraselenafulvalene (TSF) salts of tetrahalogenozinc(II) and -cadmium(II) anions D_x [MX₄] (D = TTF or TSF; M = Zn and Cd; X = Cl, Br, and I; x = 2.0-6.6) have been prepared by the reaction of [TTF]₃[BF₄]₂ or [TSF]₃[BF₄]₂ with [NEt₄]₂[MX₄] in acetonitrile and by the electrolysis of TTF or TSF in acetonitrile containing [NEt₄]₂[MBr₄]. Electrical resistivities of these salts measured for compressed pellets fall in the range 1 × (10¹–10⁷) Ω cm at 25 °C; the value decreases with increasing bulkiness of the anions: [MCl₄]^2– > [MBr₄]²⁻ > [MI₄]²⁻. Stackings and electronic states of TTF and TSF molecules are discussed on the basis of electronic reflectance, ESR, IR, and Raman spectra.     

Tetrathiafulvalene. XVI. Spektroskopische und elektrische Eigenschaften von TTF und TTF-TCNQ-Komplexen

Tetrathiafulvalenes. XVI. Spectroscopic and Electrical Properties of TTF and TTF-TCNQ-Complexes UV-vis-spectra of mono- and dications of the TTF 2 show in comparison to those of TTF 1 and 3 that the aryl substituent in the TTF 2 is more twisted from the TTF-plane than in 1 and 3 . Absorption maxima of mono- and dications from TTF 1 and 3 lie at a significantly greater wavelength than absorption maxima of mono- and dications from TTF 2 , because a better electronic interaction between substituents in the aryl-group and the positively charged dithiolium-ring is possible. TCNQ-complexes of smoother TTF 3 also have a higher electrical conductivity than TCNQ-complexes of 2 .     

Tetrathiafulvalene. VIII. Ethylenverbrückte polymere Tetrathiafulvalene

Tetrathiafulvalenes. VIII. Ethylene-bridged Polymer Tetrathiafulvalenes Syntheses and properties of ethylene-bridged polymer tetrathiafulvalenes are described. These polymers react with bromine, iodine or tetracyanoquinodimethane to form the radical cation salts, whose electrical conductivity are estimated by means of powder compactions. The polymer radical cation salts have a higher conductivity than the polymer TTF (σ_RT max. 10⁻⁵ Ω⁻¹cm⁻¹). The differences in the conductivity between polymer TTF-cationhalides and polymer TTF-TCNQ-salts are small.     

Tetrathiafulvalene. XXVII [1] Darstellung und Eigenschaften cis- und trans-isomerer Dihydrophenanthreno-Tetrathiafulvalene

Tetrathiafulvalenes. XXVII. Syntheses and Properties of cis- and trans-Isomers of Dihydrophenanthreno-Tetrathiafulvalenes The synthesis of anellated tetrathiafulvalenes (TTF) 10a–c , 11a–b via the 1,3-dithiolium salt/triethylamin or 1,3-dithiole-2-thione/triethyl phosphite route is described. The dihydrophenanthreno-anellated TTFs 10a, b can be thermally transformed into the phenanthreno-anellated TTFs 11a, b . Only in the case of the dihydrophenanthreno-anellated TTF 10b (with “α-naphthyl structure”) the isolation of the cis- and trans-isomer was possible due to differences in the solubility. Starting from the pure cis- or trans-isomer the radical salts of 10b are reducible to a 1:1 mixture of the cis/trans stereo isomers. The spectroscopic, electrochemical, and conductivity properties of the synthesized TTFs and their complexes with iodine, TCNQ, and DDQ are described.     

Anion complexation by calix[4]arene-TTF conjugates

Calix[4]arenes bearing tetrathiafulvalene (TTF) moieties appended to the upper rim via the amidic functions were synthesized and used for ¹H NMR and UV/Vis complexation studies towards selected anions. It was found that the complexation affinity towards H₂PO₄⁻ dramatically depends on the substitution pattern of the calixarene moiety. As a result, the proximally disubstituted derivative has a complexation constant by two orders of magnitude higher than the distally disubstituted analogue. The differences between proximal and distal receptors were also documented by their behaviour during the oxidation of the attached TTF units.     

New 2,2-difluoro-1,3,2(2H)oxazaborines and merocyanines derived from them

Synthetic methods have been developed to prepare oxazaborines, the azaanalogues of 2,2-difluoro-1,3,2(2H)dioxaborines, which can form merocyanine dyes. The first oxazaborine merocyanines with the isomeric position of the coordinating nitrogen atom have also been obtained. Comparing the spectral properties of donor-acceptor dioxa- and oxazaborine dyes, it is seen that substitution of the 3-O atom by the NH group in the chelate ring has a slight effect on absorption and fluorescence band positions but causes the intensity redistribution between the 0-0 and 0-1 vibronic absorption peaks and thus induces a change in the absorption band shape due to the enhanced solvation of oxazaborines. Substitution of the 1-O ring atom by the NPh group leads to a bathochromic shift and a manifold increase in the fluorescence quantum yield for the corresponding boron chelate dyes.     

Novel coumarin fluorescent dyes: Synthesis,structural characterization and recognition behavior towards Cu(II) and Ni(II)

A series of novel coumarin dyes (3–12) were designed and synthesized. The structures of the dyes were characterized by IR, ¹H NMR, ¹³C NMR, ¹⁹F NMR, MS and single crystal X-ray diffraction. 3-(2-Benzoylhydrazonotrifluoroethyl)-7-(N,N-diethylamino)coumarin (11) could recognize Cu²⁺ and Ni²⁺ selectively in aqueous solution. Upon addition of Cu²⁺ or Ni²⁺ to 11 a blue shift or a bathochromatic shift of the absorption band was observed while the emission band blue-shifted with decrease in the fluorescence intensity. Upon addition of Cu²⁺ the color of the solution of 11 changed from orange to red. The results showed that 11 could be used as an optical chemosensor of Cu²⁺ and Ni²⁺.     

Novel coumarin fluorescent dyes: Synthesis, structural characterization and recognition behavior towards Cu(II) and Ni(II)

A series of novel coumarin dyes (3-12) were designed and synthesized. The structures of the dyes were characterized by IR, ¹H NMR, ¹³C NMR, ¹⁹F NMR, MS and single crystal X-ray diffraction. 3-(2-Benzoylhydrazonotrifluoroethyl)-7-(N,N-diethylamino)coumarin (11) could recognize Cu²⁺ and Ni²⁺ selectively in aqueous solution. Upon addition of Cu²⁺ or Ni²⁺ to 11 a blue shift or a bathochromatic shift of the absorption band was observed while the emission band blue-shifted with decrease in the fluorescence intensity. Upon addition of Cu²⁺ the color of the solution of 11 changed from orange to red. The results showed that 11 could be used as an optical chemosensor of Cu²⁺ and Ni²⁺.     

The sulfonation of poly(ether ether ketone) as investigated by two‐dimensional FTIR correlation spectroscopy

Fourier transform infrared and two‐dimensional correlation (2D‐COS) spectroscopies were used to follow the structural alteration occurring upon sulfonation of poly(ether ether ketone), in concentrated sulfuric acid at room temperature. With the help of high resolution and high sensitivity 2D‐COS, it was possible to locate the aromatic ring in which the substitution has taken place. Two new IR bands at 1288 and 1320 cm^?1 were attributed to substitution occurring on the aromatic ring flanked with two ether groups. Limited oxidation effects of concentrated sulfuric acid manifested itself by the production of new carbonyl species absorbing in the IR at 1720 and 1750 cm^?1 that were attributed to a fluorenone‐type structure and to ester groups. The 2D‐COS analysis showed that the band at 1470 cm^?1 is not only due to the new substitution by sulfone groups and can not be used in the determination of sulfonation degree. Instead, the intensity of the 1490 cm^?1 band, which can be attributed to skeletal ring vibration, was found to correlate well with the degree of sulfonation calculated from ¹H NMR spectroscopy. The infrared spectroscopy combined with 2D‐COS provides a fast and powerful method for qualitative polymer structure verification and help to establish the quantitative analysis. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41242.     

Raman investigation of single oxidized carbon nanotubes

The oxidation process of single-walled carbon nanotubes via nitric acid treatment was followed by IR-, UV-Vis-NIR, and single bundle Raman spectroscopy. The introduction of functional, oxygen-containing groups is revealed by an additional absorption band at 1725 cm⁻¹, characteristic of carbonyl stretch vibrations. No significant shift of the optical absorption bands could be detected after oxidation. The combination of atomic force microscopy and confocal scanning resonance-enhanced Raman microscopy was used to investigate thin bundles and, eventually, individual nanotubes in detail. These experiments enabled determination of the dependence of the Raman intensity of the G-line (around 1590 cm⁻¹) on the bundle height for both non-oxidized and oxidized tubes. The Raman cross-section of the oxidized tubes was found to be reduced by a factor of ˜4, compared to the pristine tubes. This observation is ascribed to all tubes within a bundle that are oxidized to the same degree.     

Chemical recycling of poly(vinyl chloride): Application of partially dehydrochlorinated poly(vinyl chloride) for producing a chemically modified polymer

Poly(vinyl chloride) (PVC) pipes were chemically modified to produce a sulfonated polymer with dehydrochlorinated PVC samples as intermediates. Two intermediates were formed: (1) partially dehydrochlorinated PVC with long sequences of conjugated double bonds and (2) the product of the partial dehydrochlorination of PVC and the nucleophilic substitution of chlorine by hydroxyl groups. The IR spectra showed that the dehydrochlorinated samples were heterogeneous materials, showing different proportions of elimination products, hydroxyl substitution, and partial oxidation. Samples dehydrochlorinated with poly(ethylene glycol) with a molecular weight of 400 g/mol for 24 h and 15 min showed the highest sulfonation yield, which was related to the sulfonation mechanism occurring predominantly because of the presence of hydroxyl groups in a mixture of vinyl alcohol and vinyl chloride units. The sulfonation was confirmed by the presence of a medium‐intensity band at 1180 cm^?1, assigned to sulfonic groups. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthese et analyse electrochimiques d'un nouveau sel conducteur du tetrathiofulvalene: TTF(MnCl3)0.8

The anodic oxidation of tetrathiofulvalene in the presence of MnCl⁻₃ anions has been studied by different electrochemical techniques. A solid mixed-valence salt TTF(MnCl₃)_0,8 has been isolated; its stoichiometry has been deduced from several electrochemical analyses.     

Pyryliumverbindungen. XIV. Zur Lichtabsorption von 1,2-Benzoxalenen (Indeno[2,1-b]pyranen)

Pyrylium Compounds. XIV. The Light Absorption of 1,2-Benzoxalenes (Indeno[2,1-b]pyrans) The iso-π-electronic relationship between azulene A and the heterocyclic pseudoazulene B is reflected by the same dependence of the N V₁ transition from the substituents: Many examples ( 1 – 27 ) show that pseudo-azulenes of the 1,2-benzoxalene type (indeno[2,1-b]pyran) C undergo a bathochromic shift by alkyl substitution at C³ and C⁶, but an hypsochromic shift by alkyl substitution at C⁷. Second order substituents effect an opposite influence (examples 92 – 98 ). The conjugative effect of substituents causes a bathochromic shift in all positions (examples 49 – 58 ), which may rise to a remarkable amount with the extension of the conjugated system (examples 59 – 91 ). The relations obtained correspond to the results of quantum-chemical calculations (examples 28 – 48 ).     

Phase formation and spectral evolution of (Sr,Ba)2Si(O,N)4:Eu2+ phosphors

Sr_2‐xBa_xSi(O,N)₄:Eu²⁺ (SB_xSON:Eu²⁺) oxynitridosilicate phosphors were prepared via incorporation of N^3?, Eu²⁺, and Ba²⁺ ions into Sr₂SiO₄ (SSO) lattices. X‐ray diffraction patterns of the prepared powders revealed that SB_xSON:Eu²⁺ was a solid‐solution form of SSO. An increase in x values caused a phase transition and an expansion of the unit cell. The photoluminescence excitation (PLE) spectra of SB_xSON:Eu²⁺ were broad, covering the ultraviolet range to the visible range. Corresponding PL emission spectra strongly depended on the excitation wavelengths and consisted of two emission bands, one in the green‐blue region (A‐band) and the other in the red region (B‐band), which were assigned to Eu(I) and Eu(II), respectively. The B‐band resulted from a dramatic red‐shift of the green emission band assigned to Eu(II) of SSO:Eu²⁺, revealing that the nitridation process preferentially affected the Eu(II) sites. This behavior was explained by crystal field splitting, the fluorescence decay time, and thermal quenching. The Ba²⁺ substitution caused evolution of the PL spectra, and its effects on the spectra were discussed under consideration of ionic size and covalence.     

Synthesis, 1H-NMR and Electronic Absorption Spectra,and Halochromic Properties of Bis(1,2-dimethyl-3-indolizinyl)hetarylmethane Dyes

A series of bis(1,2-dimethyl-3-indolizinyl)hetarylmethane dyes has been synthesised, where the hetaryl substituents are 2-benzoxazolyl, 2-benzothiazolyl, 1-methyl-2-benzimidazolyl, 4- and 2-pyridyl and 4-quinolyl.The interpretations of the ¹H-NMR spectra supported the postulated structure of these dyes. The dependence of the electronic absorption spectra on the variation of the hetaryl substituents as well as on the pH^* conditions of the water/methanol solvent mixture (halochromism) is discussed on the basis of PPP-CI and HMO calculations. Analogously to trihetarylmethane dyes described earlier¹ a second-order perturbational effect could be shown to make the main contribution to the bathochromic shift on substituting the chromophoric di-indolizinylmonomethincyanine fragment at the central carbon atom. This effect was superimposed on the general first-order perturbational shift induced by the increased out-of-plane rotation of the chromophore on substitution with the bulky hetarenes.Lower dissociation constants K^* and K_R^* in comparison with the di-indolylhetarylmethane series¹ confirmed the calculated better delocalisation of the positive charge on the central carbon in the present system.     

Kinetics of absorption of oxygen in aqueous solutions: (1) acidic chromous chloride, (2) acidic titanous chloride and (3) ammoniacal cuprous chloride

The kinetics of absorption of oxygen in aqueous solutions of acidic chromous chloride and ammoniacal cuprous chloride were studied in a stirred cell. Both these reactions were found to be very fast and the theory of gas absorption accompanied by fast pseudo-m^th order reaction was used to analyse the results. The kinetics of absorption of oxygen in aqueous acidic solutions of titanous chloride were investigated in a bubble column where the reaction was found to be free from diffusional resistance.The reaction between oxygen and chromous chloride was found to be first order with respect to oxygen and second order with respect to chromous ion. The value of the third order rate constant for 2·0 M HCl solution was found to be 2·7 × 10¹² (cm³/g mole)² sec^?1 at 30°C.The oxidation of titanous chloride was observed to be zero order with respect to titanous ion and first order with respect to oxygen. The value of the first order rate constant was found to be 8·6 × 10^?3 sec^?1. It has been suggested that in this case hydrolysis precedes the oxidation and it is likely that the reaction of oxygen with the hydrolysed product is the rate controlling step.The absorption of oxygen in aqueous ammoniacal cuprous chloride was found to be third order; first order with respect to each species, namely Cu⁺, oxygen and free ammonia. The value of the third order rate constant was found to be 7·5 × 10¹⁰ (cm³/g mole)² sec^?1. The higher value of the rate constant compared to that for oxidation of acidic solutions of curpous chloride indicates that the presence of a complexing agent such as ammonia increases the rate of absorption of oxygen substantially.     

Destruction of aniline by mediated electrochemical oxidation with Ce(IV) and Co(III) as mediators

Mediated electrochemical oxidation has been employed to test the feasibility of treating soluble organic wastes. We report Ce(IV)- and Co(III)-mediated electrochemical oxidation of aniline at various electrodes in acidic media as an example of organic waste. Aniline was oxidized by an electrogenerated electron transfer mediator, Ce⁴⁺ or Co³⁺, in the anolyte and carbon dioxide was produced as a final oxidation product. Carbon dioxide was collected by bubbling through a barium hydroxide solution. When a powerful oxidizing agent, Ce(IV) or Co(III), was used as an electron shuttling mediator, parameters affecting the coulombic efficiency for aniline oxidation were the standard oxidation potentials of the mediators, their concentrations and the reaction temperature. Intermediate species produced during the oxidation of aniline were identified by cyclic voltammetric and absorption spectroscopic measurements.