Synthesis and Characterization of Polyphenothiazene Iodine Complexes

Abstract

N-methyl 3,6 dibromophenothiazene has been polymerized by using a nickel complex-assisted Grignard coupling. Vapor phase iodine doping of the organometallic polymerized material led to a conductivity increase of 10^?11 ohm^?1 cm^?1 to 10^?5 ohm cm^?l at room temperature. The complex thus formed exhibited a semiconductor behavior with a thermal activation energy of 0.1 eV and a strong electronic IR absorbance from 4000–400 cm^?1. However, the complexed polymer could be dissolved in liquid I₂ and cast into films with air stable, room temperature conductivities as high as 1 ohm^?l cm^?l. The mechanisms that could give rise to these differences in behavior will be discussed.     

Octahedral Copper(II) Carboxylates with 1,10-Phenanthroline: Synthesis,Structural Characterization,DNA-Binding and Anti-Fungal Properties

Two mono-nuclear axially distorted octahedral copper(II) complexes have been prepared and characterized via FT-IR, UV–Visible, elctrochemical, electron spin resonance and powder and single crystal XRD techniques. The complexes consist of a phenanthroline and two carboxylate ligands each bonded in bidentate fashion. Carboxylates are ortho-nitro-2-phenyl acetate (L1) and para-chloro-2-phenyl acetate (L2). Structural study showed that both complexes possess Jahn–Teller distorted octahedral geometry. The bulk purity was assessed from the matching experimental and simulated powder XRD spectra. The results of spectroscopic techniques are consistent with each other. ESR data revealed single electron occupancy of d_x² ? _y² orbital with ²B_1g as ground state typical of tetragonally distorted octahedral geometry. Electrochemical solution study showed diffusion controlled electron transfer processes with diffusion co-efficient values of 10.323?×?10^–8 cm²s^–1 and 0.972?×?10^–8 cm²s^–1 for 1 and 2. Complexes exhibited excellent DNA-binding activity studied via UV–Visible spectroscopy, cyclic voltammetry, florescence spectroscopy and viscometry yielding K_b values of 1.871?×?10⁴ M^–1 (1) and 1.577?×?10⁴ M^–1 (2), 0.38?×?10⁴ M^–1 (1) and 6.39?×?10⁴ M^–1 (2) and 2.1?×?10⁶ M^–1 (1) and 2.0?×?0⁶ M^–1 (2), respectively, for the first three techniques. Complexes possess good antifungal activity against three fungal strains.

Graphic Abstract

     

Electronic and Ionic Conductivity in Polyiodine Complexes of Benzophenones and Coumarin

Abstract

Complexes of benzophenone, benzophenone derivatives, or coumarin with alkali or ammonium iodides and iodine have been prepared and their conductivities studied. The organic sub-lattices involve six- or four-coordinate cation clathrated by the carbonyl compounds. The iodine sub-lattices consist of I_n chains in which I₃ ^? and I₅ ^? ions can be identified. AC (1 KHz) conductivities at room temperature vary from 10^?1 to 10^?6 Ω^?1 cm^?1, and are of a mixed ionic and electronic type. The most likely transport mechanism involves hopping processes in the polyiodine sub-lattice.     

Crystal Structure of a Non-Conductive Non-Stoichiometric Tetrathiafulvalenium Salt: (TTF)3(BF4)2

Abstract

(TTF)₃(BF₄)₂ crystallizes in the triclinic system, space group P1, a = 8.017(3), b = 8.601(1), c = 11.635(2) Å, α = 108.79(1), β = 100.96(2), γ = 99.09(2)°, Z = 1. The TTF entities are stacked in parallel columns arranged into parallel layers alternating with layers of BF₄ ^? anions. A TTF stack is constituted of (TTF⁺)₂ diads interspersed with TTF° monads; the TTF⁺-TTF⁺ overlap is of the ring-over-ring type while the TTF⁺-TTF⁺ overlap is of the bond-over-ring type. These features explain the low conductivity ([sgrave]_powdcr = 2 × 10^?5 Ω^?l cm^?1) of this apparently non-stoichiometric TTF salt.     

Raman Scattering From TMTSF-Salts

Abstract

Experimental results for Raman scattering from TSeF, TMTSF-D12, (TMTSF)₂PF₆ and (TMTSF)₂AsF₆ excited with blue-green laser light at liquid nitrogen temperature are reported. A strong resonance effect for excitation of TMTSF with 4579 Å was observed and an assignment for the a_g modes was obtained by comparison with results from TTF. Methyl group modes were identified at 328 cm^?1, 472 cm^?1 and 916 cm^?1, respectively. Charging the TMTSF molecule resulted in a strong frequency shift of -122 cm^?1 and -76 cm^?1 for the a_gu₂ mode, respectively. A study of the temperature dependence of the scattering from molecular modes between 2 K and 300 K did not reveal any correlation with the phase transitions in the conducting compounds.     

Triplet Excitions in Crystalline Trans-Stilbene I. Spectroscopy of the So → T1 Transition

Abstract

The first singlet → triplet absorption of trans-stilbene has been studied between 10 and 300 K. The triplet exciton energy (energy of the lowest 0–0 line) is 17380 cm^?1 at 10 K, and does not change significantly with temperature. Vibrational A_g modes of 206. 1250 and 1570 cm^?1 are active. The Franck-Condon factor of the origin region is small. The low temperature spectra of the 0–0 and 206 cm^?1 regions show a doublet structure with a splitting of 82 ± 1 cm^?1 which is attributed to the site splitting. Further structure shown by the lines is discussed. The lines are approximately lorentzian. From curve fitting, line-widths and exciton-phonon coupling constants, increasing linearly with T, are deduced. Exciton-phonon coupling appears to be different on the two sites. The product of absorption coefficient at 4880 Å, α, by the total triplettriplet interaction rate constant has been measured at 295 K: αγ=2.3 ± 0.3. 10^?15 cm² sec^?1, corresponding for γ_total to a value of a few 10^?12 cm³ sec^?1.     

Measurement of Singlet Exciton Diffusion Coefficient in the C′-Direction in Crystalline Naphthalene

Abstract

The diffusion coefficient of singlet excitons in the c¹ direction in crystalline naphthalene has been deduced from the temporal analysis of fluorescence quenching at the surface by an Al layer, D_C ¹ = 5 × 10^?5 cm² s^?l, corresponding to a diffusion length A_C ¹ = 230 Å.     

In Situ Raman and Epr Investigations of A Cis-(Ch)X Electrode

Abstract

In situ Raman and EPR experiments have been performed on a cis-(CH)_x electrode in an electrochemical cell {(CH)_x/1M L1C10₄ in THF/Li}. After a n-type doping with Li, the Raman spectra exhibit new features at = 1600 cm^?1 and 1270 cm^?1, comparable to those obtained with [CH)_X films Li doped via a chemical treatment. The evolution of the EPR signal is followed in a doping-dedoping cycle, showing both the reversibility of the process as well as the evidence for a metallic behavior at the maximum doping concentration.     

Globular Mesogens

Abstract

Polyaniline, (4oSN) is found to exhibit a low energy absorption edge beginning near 1800 cm^?1 (ca: 0.22 eV), and a strong anion-induced absorption from about 800 to 1200 cm^?1. Electrical conductivity has an activation energy of 0.05 (15%) eV consistent with an anion-induced energy gap of about 0.1 eV.     

Highly Conductive TCNQ Salts of Cu Chelates

Abstract

Cu(II) chelates with ethylenediamine, 2,2′-bipyridine, 1,10-phenanthroline and their analogues form highly conductive TCNQ salts CuL_n(TCNQ)₂. The powder conductivity at room temperature amounts to 7 × 10^?4-1.9 Ω_?1cm^?1, depending on the coordinating ligands. The ESR and magnetic susceptibility studies indicate that the Cu atoms of the complexes have incomplete oxidation states.     

Migration and Annihilation of Triplet Excitation Energy in the Charge-Transfer Anthracene-Tetrachlorophtalic Anhydride Crystal

Abstract

The emission spectra of the charge-transfer crystal of anthracene-tetrachlorophtalic anhydride were studied in the 1.7-300 K temperature range. Delayed fluorescence was observed over the whole temperature range. At temperatures below ～40 K it results from heterogenous (mobile exciton-trapped exciton) triplet-triplet annihilation. At higher temperatures it is due to homogenous triplet-triaplet annihilation. The existence of mobile excitons is also proved by the character of the ESR lines which are very narrow Lorentzians. The phosphorescence, observed only in the range 1.7–40 K, originates from at least two different kinds of traps with energies ～6 cm^?1 and ～140 cm^?1, respectively. The vibrational structure of the phosphorescence is identical to that of anthracene, with 0—0 band blue-shifted by ～400cm^?1. A kinetic model of trapping and detrapping of triplet excitons as well as the nature of the traps are discussed.     

Heat Capacity and Thermodynamic Properties of p'-Substituted p-n-Hexyloxybenzylideneaniline. I. p-n-Hexyloxybenzylideneamno-p'-Benzonitrile (HBAB)

Abstract

The heat capacity of the nematogenic liquid crystal, HBAB, has been measured between 15 K and 385 K by using an adiabatic calorimeter. The crystal-crystal phase transition has been discovered at 27 K below the crystal-nematic phase transition temperature. The transition temperatures, the enthalpies and the entropies of the three phase transitions have been determined: T ₁ = 306.98 K, ΔH _t = 5.11 kJ mol^?1, ΔS _t = 16.7 JK^?l; T _m = 334.05 K, ΔH _m = 23.77 kJ mol^?1, ΔS_m = 71.2 J K^?l mol^?1; and T _c = 375.10 K, ΔH _c = 1.75 kJ mol^?1, ΔS _c = 3.2 J K^?1 mol^?1, respectively. The thermodynamic functions of HBAB from 0 K to 385 K have been determined from the heat capacity data and the enthalpies of the transitions. Two crystal modifications, one yellow and granular form and the other white and needle-like form, have been obtained during the course of the preparation of the sample. It turned out that the yellow form was the stable crystal and the white the metastable modification. The crystal-crystal phase transition has been discussed as an onset of partial melting from the entropy consideration. In this connection the total entropies of the transitions, 91.1 J K^?1 mol^?1 has been proposed to be an important measure of melting.     

Magnetic Resonance on (QP)4(SbF6)3, a Radical Cation Salt of P-Quaterphenylene

Abstract

The unit cell of (QP)₄(SbF₆)₃ shows triads of QP in an arene stack and one QP in the anion sheet. The sum formula is therefore (QP)₃QP(SbF₆)₃. Electron-electron repulsion force le^?/site resulting in a semi-conducting state. This is in agreement with an activated conductivity of max 10^?1 Scm^?1 at 300 K.

Magnitude and activation energy of the paramagnetic susceptibility do not coincide with those of the conductivity; spins and charges are localized and decoupled due to the strong alternation of distances within the cation stack. Spin diffusion along the stacks governs, at least above 180 K, the magnetic properties: narrow ESR-lines and proton spin relaxation via hyperfine interaction with the relaxation dispersion T ^?1 _1H α ω^?1/2 above 200 K.

A lower value for the intrachain exchange rate τ₁ ^?1> 8.10¹¹ sec^?1 and a lower limit of 10³ for the anisotropy can be evaluated.

Keywords: quaterphenylene, molecular crystal, radical cation salt, low dimensionality, magnetic resonance     

Electron Spin Resonance In CuCrS2 and CuCrSe2 Single Crystals

Abstract

Single crystal ESR spectra of CuCrS₂ and CuCrSe₂ have been measured at both X- and Q-band frequencies. Anisotropic signals from the localised Cr³⁺ d-electrons give zero-field splitting parameters of 0.29cm^?1 and 0.31cm^?1 for the sulphide and selenide respectively, suggesting a possible orbital interaction between the Cr and Cu ions. The dependence of the ESR parameters on temperature shows the effect of magnetic ordering.     

Spectres de vibration du Cristal de Biphényle à Basse Température

Abstract

Low-temperature infrared and Raman spectra of Crystalline biphenyl have been investigated in the 3100–25 cm^?1 range, and those of biphenyl-D₁₀ between 200 and 25 cm^?1. The infrared dichroism of an Oriented crystal at 77°K has been measured in the 3100–400 cm^?1 region. The assignment for the internal modes V ₅(B_2u), v ₆ (B_2u), v ₁(B_1u), v ₁₀(B_1g), v ₂(B_2g) et v ₃ (B_3g) is given.

The band splitting is analized and hte components due ot the correlation effect in the fundamentals are separated from the components due to combinations. Isotopic shifts are used to assign the nine external vibrations as well as the torsional mode. The temperature effect on the frequencies occuring below 500 cm^?1 is discussed.     

Conductivity and Optical Properties of a Polyiodine Canal Complex (Benzophenone)9(KI)2I7, CHCl3

Abstract

(Benzophenone)₉(KI)₂I₇, CHCl₃ single crystals have a golden metallic reflection on the surfaces parallel to the polyiodine chain axis. The compound is a member of a large class of channel-like inclusion compounds in which isolated iodine atom chains are the only possible conducting strands in an otherwise insulating matrix. The (contactless) microwave conductivity is ～ 10 Ω^?1 cm^?1 at room temperature with an activation energy of ～0.03 eV down to 70°K, while the dc conductivity is ～10^?-⁶. Conductivity is strongly frequency dependent and contact problems are severe.     

Raman Investigation of Alkali-Doped (Ch)x films

Abstract

Resonance Raman spectra induced by (CH)_x films chemically or electrochemically doped with alkali metals are reported. At low doping levels, Raman bands characteristic of the trans isomer are observed. The Raman spectra can be well fitted using the theory developped by Mulazzi based on a bimo-dal distribution of long and short trans segments respectively. At the same time, typical results obtained for a cis-rich (CH)_x sample, as well as its behavior during a thermal isomerization, are recalled in the frame of the Mulazzi model. When the polymer is highly doped with Li (or Na) atoms, new features at ? 1600 cm^?1 and 1270 cm^?1 appear and could be an indication that n-doped films are less disordered than p-doped systems.     

Etude par Calorimetrie,Diffraction des Rayons X et Diffusion Raman d'une Transition de Phase dans (C4 H4P) Mn (CO)3

Abstract

Heat capacity measurements (95-300K), X-ray diffraction (78-300K) and low frequency Raman spectroscopy (10-350K) have evidenced an order-disorder phase transition in phosphacymantrene, (C₄ H₄P) Mn (CO)₃. This transition has been characterized by a monoclinic ←→ triclinic structural change at about 110 K and by a pretransitional phenomenon. The measured transition enthalpy and entropy are 480 ± 10J.mil^?1 and 4.17 ± 0.08J.K^?1 mol^?1, at 115 K, respectively.

A complete assignment of the observed Raman bands in h₄ and d₄ derivatives is proposed. From the temperature dependence of frequencies, intensities and half-widths of some Raman bands we have discussed the order, the nature and the mechanism of the phase transition: intermolecular interactions appear to be mainly involved in the mechanism and an activation energy roughly equal to 2100 ± 840 J. mol^?1 has been determined.     

Solitons in Polyacetylene Induced and Probed by Positive Mupons

Abstract

Positive muons were injected into both trans- and cis- (CH) as well as (CD)_x. In cis-polyacetylene, the μ⁺ was found to form a radical state with an unpaired electron localized near the μ⁺ In trans-polyacetylene, the longitudinal μ⁺ spin relaxation rate at 293 K showed H^?1/2 dependence on the applied field H. After considering possible mechanisms, we concluded that it is due to the soliton-like one-dimensional motion of induced unpaired electron.     

3D direct ink writing fabrication of high-performance all-solid-state micro-supercapacitors

Abstract

We present the fabrication of flexible all-solid-state micro-supercapacitors (MSCs) by using 3D direct-ink-writing (DIW) technique. The conductive poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) ink was printed by layer-by-layer fashion on flexible substrates. The MSC electrodes exhibit smooth surface and low sheet resistance. The flexible MSC fabricated by 3D DIW exhibits the areal capacitance per electrode of 31.6 mF cm^?2, gravimetric capacitance of 15.6?F g^?1, an energy density of 0.36 µWh cm^?2, and power density of 80?µW cm^?2. The flexible MSC shows high cyclic and bending stability. We believed that the optimized 3D DIW fabrication has potential for roll-to-roll 3D printing flexible all-solid-state MSCs.