UV Vis Spectroelectrochemical Studies Research Articles

Exploring the synergistically enhanced activity of novel α-MnSe/ppy composite for superior OER catalyst in alkaline medium

The extremely slow kinetics of the water-splitting process stymies the synthesis of hydrogen (H2) from water. To comprehend the main obstacle to the oxygen evolution reaction (OER), it is also necessary to enhance the development of efficient OER electrocatalysts. In this work, manganese selenide with polypyrrole heterostructure is synthesized, described, and electrochemically assessed as an effectiveelectrocatalystfor OER. The novel synthesized materialis characterizedusing a variety of techniques, including scanning electron microscopy (SEM), powder x-ray diffraction (PXRD), transmission electron microscopy (TEM) etc. The unique α-MnSe/ppy composite catalyst is shown to be exceedingly efficient, starting the OER at an astoundingly low voltage of 168 mV (vs. reversible hydrogen electrode [RHE]) at 10 mA cm−2, with a tafel slope of 67 mV dec-1. Also, operando UV–Vis spectro-electrochemical studies give an insight towards the intermediate species formed during the OER catalysis. Under similar electrochemical conditions, the α-MnSe/ppy electrocatalyst outperforms its α-MnSe and ppy counterparts for OER in an aqueous KOH (1.0 M) solution. These results surpass benchmark electrocatalysts made of Mn and rare earth metals. With this invention, a desired non-noble metal is made available that works excellently as an OER electrocatalyst.

Further Exploration of Aza-Cobalt-Cyclobutenes on CoIII(TIM) Complexes: Reactivity and Spectroelectrochemistry

The reaction between [CoIII(TIM)Cl2]PF6 (TIM is 2,3,9,10-tetramethyl-1,4,8,11-tetraazacyclotetradeca-1,3,8,10-tetraene) and electron-rich terminal alkynes (HC2Y, Y = 4-N,N-bis(4-methoxyphenyl)aniline (TPA) or Fc) yielded a pair of constitutional isomers: 1-aza-2-cobalt-cyclobutene-containing trans-[Co(TIM′)((HC═C)Y)Cl]+ (1a (TPA) and 2a (Fc); TIM′ is the resultant derivative of TIM) and σ-coordinated trans-[Co(TIM)(C2Y)Cl]+ (1b (TPA) and 2b (Fc)). Additionally, the reactivity of the 1-aza-2-cobalt-cyclobutene species was explored based on trans-[Co(TIM′)((HC═C)Fc)Cl]PF6 (2a) because of its good synthetic yield. The reaction of 2a with AgOTf in MeCN resulted in trans-[Co(TIM′)((HC═C)Fc)(NCMe)](PF6)(OTf) (3), and the reaction with KCN in MeOH yielded trans-[Co(TIM′)((HC═C)Fc)CN]PF6 (4). Similarly, trans-[Co(TIM)(C2Ph)(CN)]PF6 (5) was prepared from the reaction between KCN and trans-[Co(TIM)(C2Ph)Cl]PF6. Molecular structures of 1b and 3–5 were established through single crystal X-ray diffraction. Electrochemical studies of 2–4 revealed that these complexes display an irreversible CoIII reduction as well as a reversible one electron ferrocenyl oxidation between 0.11 and 0.18 V (vs Fc+1/0). UV–vis spectroelectrochemical studies revealed a CoIII to Fc+ charge-transfer upon the one electron oxidation of 2a and 2b.

Electrocatalytic CO2 Reduction with a Binuclear Bis-Terpyridine Pyrazole-Bridged Cobalt Complex.

A pyrazole-based ligand substituted with terpyridine groups at the 3 and 5 positions has been synthesized to form the dinuclear cobalt complex 1, that electrocatalytically reduces carbon dioxide (CO2 ) to carbon monoxide (CO) in the presence of Brønsted acids in DMF. Chemical, electrochemical and UV-vis spectro-electrochemical studies under inert atmosphere indicate pairwise reduction processes of complex 1. Infrared spectro-electrochemical studies under CO2 and CO atmosphere are consistent with a reduced CO-containing dicobalt complex which results from the electroreduction of CO2 . In the presence of trifluoroethanol (TFE), electrocatalytic studies revealed single-site mechanism with up to 94 % selectivity towards CO formation when 1.47 M TFE were present, at -1.35 V vs. Saturated Calomel Electrode in DMF (0.39 V overpotential). The low faradaic efficiencies obtained (<50 %) are attributed to the generation of CO-containing species formed during the electrocatalytic process, which inhibit the reduction of CO2 .

Electrochromic properties of a polydithienylpyrrole derivative with N-phenyl pyrrole subunit

In this report, a new N-phenyl typed 2,5-dithienyl pyrrole compound bearing pyrrole unit was successfully synthesized and its conjugated homopolymer, poly(1-(4-(1H-pyrrol-1-yl)phenyl)-2,5-di(thiophen-2-yl)-1H-pyrrole) (P(SNS-Ph-Pyr)), was obtained in the medium of 0.1 M TBAPF6/DCM via electroanalytical methods. Cyclic voltammetry and FTIR studies proved that monomer SNS-Ph-Pyr was synthesized and polymerized electrochemically and its corresponding polymer film, P(SNS-Ph-Pyr)) has a well reversible redox peaks at about 0.70/0.50 V vs. Ag/AgCl reference electrode in monomer free solution with a long term reversible redox behavior. The in situ UV–visible spectroelectrochemical studies of polymer film exhibited that electrochromic P(SNS-Ph-Pyr)) film had a color transition between yellow (at reduced state (0.0 V)) to grayish blue (at oxidized state (1.0 V)) with a intermediate color (green at 0.70 V). Moreover, electrochromic switching studies displayed that polymer film (coated with a thickness of 100 mC/cm2) had average optical contrast values (15.6% (383 nm), 19.5% (650 nm) and 41.7% (900 nm) but high coloration efficiency values (220 cm2/C (383 nm), 264 cm2/C (650 nm) and 384 cm2/C (900 nm).

Regioselective synthesis of novel 5-nitro-naphthoquinone derivatives: Electrochemistry and in-situ spectroelectrochemistry properties

The novel N-,O-substituted-5-Nitro-1,4-naphthoquinones (NQ) as regioisomers were synthesized by reactions of 2,3-dichloro-5-nitro-1,4-naphthoquinone with some heterocyclic rings which were substituted with various nucleophiles according to a Michael 1,4-addition mechanism. All synthesized compounds were characterized by elemental analysis, electrospray ionization mass spectrometry (ESI-MS), Fourier transform infrared spectroscopy (FT-IR), 1H-nuclear magnetic resonance (1H NMR) and attached proton testnuclear magnetic resonance (APT-NMR). Two-dimensional techniques 1H–1H correlated spectroscopy (COSY) was used for characterization of compound 1a. Cyclic and square wave voltammetric and in situ UV–Vis spectroelectrochemical characterizations of NQ derivatives were carried out to determine redox mechanism of these molecules. Although in-situ FT-IR spectroelectrochemical studies of these type compounds were frequently reported in the literature, this is the first study for the in-situ UV–Vis spectroelectrochemical studies of NQ compounds in the literature. All NQs illustrated two NQ based and one nitro-based reduction reactions. While NQ based reduction couples were electrochemically and chemically reversible, observation of nitro reduction at more negative potentials made all processes irreversible. Altering the substituents of the NQ derivatives slightly influenced the redox potentials and chemical reversibility of the processes. Isomers of different NQ derivatives almost showed similar voltametric responses. Distinct spectral and color changes were observed during the redox reactions which indicated possible usages of these molecules in display technologies.

Aqueous UV–VIS spectroelectrochemical study of the voltammetric reduction of graphene oxide on screen-printed carbon electrodes

Two graphene oxide (GO) materials with different layer size and proportion of functional groups in the basal planes (hydroxyl and epoxy) and in the edges (carbonyl and carboxyl) were used to modify the surface of commercially available screen-printed electrodes. Cyclic voltammetry in 0.1M KNO3 was evaluated as an easy to use electrochemical methodology to reduce GO attached to the surface of screen-printed electrodes (SPEs). A cathodic peak related to the reduction of GO was identified, and the peak potential was correlated to the difficulty to reduce GO to electrochemically reduced graphene oxide (ERGO) depending on the functional groups present in the basal plane and in the edges of the original GO monolayers. Time-resolved UV–VIS absorption spectroelectrochemistry in near-normal reflection mode on a screen-printed electrode is used for the very first time as an in situ characterization technique for real-time monitoring unambiguously the electrochemical reduction of graphene oxide.

Structural, spectroscopic and theoretical studies of a diruthenium(II,II) tetraformamidinate that reversibly binds dioxygen

The reaction of Ru2(O2CMe)4 with N,N′-bis(3,5-dimethoxyphenyl)formamidine (Hdmof) in refluxing toluene solutions yields Ru2(dmof)4 as a diamagnetic red solid that is extremely air-sensitive. The crystal structure reveals the expected paddlewheel arrangement of ligands around the Ru24+ core, with a relatively long Ru–Ru bond (2.4999(8)Å) that is consistent with a σ2π4δ2π∗4 electronic configuration. This is supported DFT calculations that show this electronic structure results from destabilization of the δ∗ orbital due to antibonding interactions with the formamidinate ligands. The cyclic voltammogram of Ru2(dmof)4 in a 0.1M nBu4NPF6/CH2Cl2 solution shows two redox processes, assigned as successive oxidations corresponding to the Ru24+/5+ and Ru25+/6 redox couples. Changes in the electronic absorption spectra associated with these oxidation processes were probed using a UV–Vis spectroelectrochemical study. Ru2(dmof)4 reacts with dioxygen in solution to generate a purple compound that decomposes within an hour at room temperature. Bubbling N2 gas through the purple solution regenerates Ru2(dmof)4, as evidenced by UV–Vis spectrometry and cyclic voltammetry, suggesting that the dioxygen reversibly binds to the diruthenium core.

EPR and UV–vis spectroelectrochemical studies of diketopyrrolopyrroles disubstituted with alkylated thiophenes

EPR and UV–vis spectroelectrochemical behavior of a series of ambipolar donor–acceptor–donor (DAD) compounds, consisting of a diketopyrrolopyrrole (DPP) central unit symmetrically disubstituted with mono-, bi- and terthiophene, is reported. All derivatives studied undergo a reversible reduction to radical anions at E ca. −1.55V to ca. −1.65V vs Fc/Fc+. Electrochemically generated radical anions are sufficiently stable to be detected at RT. Two-step oxidation of these compounds involves the formation of radical cations in the first step followed by their transformation into spinless dications in the second one. The formed radical cations are detectable at RT, however, contrary to the case of radical anions they yield unresolved EPR spectra. The potential of their formation depends on the length of D segment decreasing from ca. 0.50V vs Fc/Fc+ for monothiophene disubstituted DPP to ca. 0.25V in the case of the terthiophene derivative. Combining differential pulse voltammetry with EPR and UV–vis spectroelectrochemistry allows for unequivocal identification of all new, electrochemically induced UV–vis bands to particular forms of the studied molecules (radical anions, radical cations or dications). Both electrochemical reduction and electrochemical oxidation processes involve profound and distinctly different spectral changes in the visible range of the spectrum. Since they are reversible, the studied compounds can be considered as promising multicolor electrochromophores.

In situ UV–vis spectroelectrochemical study of dye doped nanostructure polypyrrole as electrochromic film

In the present work, the electrosynthesis and the spectroelectrochemical characterization of eriochrome cyanine R (ECR) doped polypyrrole (PPy) were described. Nanostructured PPy–ECR film was electrochemically deposited onto fluorine doped tin oxide (FTO) coated/glass electrode from aqueous solution containing a water-soluble trianionic dye, ECR, as dopant. The surface morphology was studied using scanning electron microscopy (SEM) analysis. Dye doped polymer film showed spherical morphology with primary particles 70–90nm in size and 900nm thicknesses. The main characteristics of PPy–ECR film include uniformity, stability and adherent on FTO electrodes, which are better compared to that of PPy film. In situ UV–vis spectroelectrochemistry was used as a powerful tool in analyzing the evolution of the neutral, polaron and bipolaron states in prepared polymer films as they were redox cycled (from −0.6V to +0.6V) in NaClO4. As the polymers gets oxidized, the intensity of the π–π* transition (neutral state) decreases while the charge carrier bands at longer wavelengths (polaron band and bipolaron band) increases in intensity and the color of the polymers change. We found that these variations are more intense in the case of dye doped to those of PPy. The spectroelectrochemical studies showed that the electrochromic properties of dye doped polymer (PPy–ECR) such as optical contrast (27%), switching time (⩽1.5s) and film stability (100 cycles) were greatly enhanced relative to the PPy film.

Electrochemical Evidence for Intermolecular Proton-Coupled Electron Transfer through a Hydrogen Bond Complex in a p-Phenylenediamine-Based Urea. Introduction of the “Wedge Scheme” as a Useful Means To Describe Reactions of This Type

The electrochemistry of several p-phenylenediamine derivatives, in which one of the amino groups is part of an urea functional group, has been investigated in methylene chloride and acetonitrile. The ureas are abbreviated U(R)R', where R' indicates the substituent on the N that is part of the phenylenediamine redox couple and R indicates the substituent on the other urea N. Cyclic voltammetry and UV-vis spectroelectrochemical studies indicate that U(Me)H and U(H)H undergo an apparent 1e(-) oxidation that actually corresponds to 2e(-) oxidation of half the ureas to a quinoidal-diimine cation, U(R)(+). This is accompanied by proton transfer to the other half of the ureas to make the electroinactive cation HU(R)H(+). This explains the observed irreversibility of the oxidation of U(Me)H in both solvents and U(H)H in acetonitrile. However, the oxidation of U(H)H in methylene chloride is reversible at higher concentrations and slower scan rates. Several lines of evidence suggest that the most likely reason for this is the accessibility of a H-bond complex between U(H)(+) and HU(H)H(+) in methylene chloride. Reduction of the H-bond complex occurs at a less negative potential than that of U(H)(+), leading to reversible behavior. This conclusion is strongly supported by the appearance of a more negative reduction peak at lower concentrations and faster scan rates, conditions in which the H-bond complex is less favored. The overall reaction mechanism is conveniently described by a "wedge scheme", which is a more general version of the square scheme typically used to describe redox processes in which proton transfer accompanies electron transfer.

A comparative study of the UV–vis spectroelectrochemical behavior of 2- and 3-methylaniline during homo- and copolymerization with 1,2-diaminobenzene

This paper evaluates comparatively the behavior of 2-methylaniline (2-MA) and 3-methylaniline (3-MA) in a UV–vis spectroelectrochemical study of their homo- as well as copolymerization with 1,2-diaminobenzene (1,2-DAB). The homopolymers poly(2-methylaniline) (P2-MA) and poly(3-methylaniline) (P3-MA) show similar spectroelectrochemical properties. However, differences were observed in the properties between the copolymers of 2-MA and 3-MA with 1,2-DAB that could be due to the variation in the monomer units and orientation along the copolymer chains. The formation of head-to-tail coupled p-aminodiphenylamine (PPD) type of mixed dimers/oligomers, presumably resulting from the dimerization of 1,2-DAB and 2-MA or 3-MA cation radicals, is proposed. An absorption peak around λ=497nm in the UV–vis spectra is assigned to these intermediates. A mechanism is proposed for the growth of the copolymers. Characteristic UV–vis features of the copolymers have been identified and their dependencies on the electrode potential are discussed. Clear variations in spectroelectrochemical properties of the materials from mixed solutions can be observed just by varying the concentration of 1,2-DAB and by replacing 3-MA with 2-MA in the feed. One of the possible reason for the difference in the properties of the copolymers of 2-MA and 3-MA might be the effect of the electron-donating methyl group in meta-position resulting in an increased electron density in the second meta-position contributing to meta-coupling of radical cations.

Unusual condensation of ethylene glycol with coordinated 1,10-phenanthroline-5,6-dione in [Ru(phen-dione)2Cl2] and its cyclometallated complex, [Ru(phpy-κ2N,C2′)(phen-diox)2](PF6)

A novel cyclometallated Ru(II) derivative of 1,10-phenanthroline-5,6-dione (phen-dione), [Ru(phpy-κ2N,C2′)(phen-diox)2](PF6), where phpy-κ2N,C2′ is 2-phenylpyridine and phen-diox is 2,3-dihydro-4a,12b-(epoxyethanooxy)[1,4]dioxino[2,3-f][1,10]phenanthroline, has been prepared by the metal-assisted effect of [Ru(phen-dione)2Cl2] via an unusual condensation of the coordinated phen-dione ligand with ethylene glycol which led to the formation of [Ru(phen-diox)2Cl2]. The condensation reaction could not proceed in the absence of [Ru(phen-dione)2Cl2]. DFT calculations showed that the energy of the LUMO of [Ru(phen-dione)2Cl2] is about 12.430kcal/mol lower than that of the uncoordinated phen-dione ligand. The cyclometallated complex has been characterized by elemental analysis, spectroscopic and spectroelectrochemical (SEC) techniques, cyclic voltammetry and X-ray crystallography. X-ray analysis of the complex shows an elongation of one of the five Ru–N bonds due to a strong trans effect of the carbanionic ligand. The electrochemical data of the complex demonstrate a strong σ-donating character of the anionic phenylpyridine ligand. UV–vis spectroelectrochemical studies of the complex in acetonitrile show a reversible redox behavior, evaluated by the maintenance of isosbestic points in the UV–vis spectrum for both forward oxidation and reverse reduction processes. The complex is very weakly emissive at room temperature in degassed acetonitrile with λem=546nm and ϕem=0.02%.

Dinuclear iridium(iii) complexes of cyclometalated fluorenylpyridine ligands as phosphorescent dopants for efficient solution-processed OLEDs

Phosphorescent cyclometalated dinuclear iridium(III) complexes of fluorenylpyridine ligands bridged by bis(μ-Cl) and bis(μ-NCO) units have been synthesised and characterised by NMR, UV-vis absorption and emission spectroscopy, cyclic voltammetry, spectroelectrochemistry and X-ray diffraction. The complexes display green luminescence in solution from mixed 3π–π*/3MLCT (metal-to-ligand-charge transfer) states in the range of λmax 542–552 nm. The solution PL quantum yields of 21–41% are remarkably high for diiridium complexes. Cyclic voltammetric and UV-visible spectroelectrochemical studies establish that the mixed valence cations are stable with the two Ir3+/Ir4+ centres interacting strongly. DFT/TD-DFT calculations provide further insights into the electronic and photophysical properties of the complexes, with good agreement between computed and experimental data. Solution-processed organic light emitting devices (OLEDs) using the diiridium complexes as the emissive dopants in poly(9-vinylcarbazole) (PVK) host polymer exhibit performances of up to 12 cd A−1 and external quantum efficiencies of up to 4%. The device architecture is: ITO/PEDOT:PSS/PVK–complex (5 wt%)–PBD (40 wt%)/Ba/Al. These electroluminescence efficiency values are unusually high for dinuclear metal complexes and confirm that dinuclear iridium complexes are suitable phosphors for OLEDs using simple device architectures. Analogous mononuclear fac-Ir(III) complexes of fluorenylpyridine ligands are reported for comparison. They have PL quantum yields of 30–43%, device performances of up to 26 cd A−1 and external quantum efficiencies of up to 8.6%.

Fabrication of Hybrid Diamond and Transparent Conducting Metal Oxide Electrode for Spectroelectrochemistry

A novel diamond transparent electrode is constructed by integrating conductive diamond film and transparent conducting metal oxide to combine the superior electrochemical properties of diamond and the electrical conductivity of transparent metal oxide (TCO). Direct growth of diamond on indium tin oxide (ITO) and aluminium doped zinc oxide (AZO) was explored, but X-ray photoelectron spectroscopy measurement reveals that both substrates cannot survive from the aggressive environment of diamond growth even if the latter is regarded as one of the most stable TCO. As a second route, a diamond membrane in silicon frame was prepared by selective chemical etching, and a diamond optically transparent electrode (OTE) was constructed by assembling the diamond membrane on the top of an ITO-coated substrate. The resulting device exhibits a high optical transparency and quasireversible electrochemical kinetics, which are competitive to other diamond OTEs reported previously. Its application in UV-Vis spectroelectrochemical studies on the oxidisation of 4-aminophenol was demonstrated.

The mononuclear ruthenium(III)-2,3,5,6-tetrakis(2-pyridyl)pyrazine complex [Ru(bpy)(tppz)Cl][PF6]2: synthesis, crystal structure, electrochemical, and spectroelectrochemical studies

The mononuclear Ru(III) complex, [Ru(bpy)(tppz)Cl][PF6]2.acetylacetone, where tppz is 2,3,5,6-tetrakis(2-pyridyl)pyrazine and bpy is 2,2′-bipyridine, has been prepared and characterized by physicochemical and spectroscopic methods, cyclic voltammetry, and single crystal X-ray structure analysis. The coordination around the Ru(III) center is distorted octahedral, with bite angles of 80.70–161.83° for the chelating bpy and tppz ligands. The two pyridyl rings of the bpy ligand are nearly coplanar. UV–vis spectroelectrochemical studies of this complex in acetonitrile showed a reversible redox behavior evaluated by the maintenance of isosbestic points in the UV–vis spectrum for both forward reduction and reverse oxidation processes. Magnetic susceptibility data derived from paramagnetic NMR data revealed an effective magnetic moment of 1.79 BM at room temperature.

A Spectroelectrochemical Study of Homo-/Co-oligomerization and Homo-/Copolymers of o-Phenylenediamine and o-Toluidine

Results of in situ UV-visible (UV/vis) spectroelectrochemical studies of the electro-oxidation of -phenylenediamine (OPD), -toluidine (OT), and their mixtures, as well as the redox activity of the obtained polymer films, performed in an aqueous acidic solution at an indium-doped tin oxide-coated glass electrode, are reported. UV-vis spectra recorded at different time intervals during the electrolysis of mixed solutions, containing a constant concentration of OT and various OPD concentrations in the feed, are different from those obtained with single monomer solutions. A band at was assigned to the head-to-tail mixed dimer/oligomer resulting from the cross reaction between OPD and OT cation radicals. At lower OPD feed concentration this band appears as the major band. The dependence of the spectral characteristics of the copolymer films on the OPD feed concentration was deduced. The UV-vis spectra of the copolymers reveal that the copolymer backbone probably consists of a mixture of copolymer chains with different monomer contents and has a significant number of block segments. Fourier transform infrared spectral analysis of the copolymers suggests the presence of both OPD and OT units and thus the formation of a copolymer during the electrolysis of mixed solutions of OPD and OT.

In situ UV–vis spectroelectrochemistry of poly( o-phenylenediamine- co- m-toluidine)

Results of in situ UV–vis spectroelectrochemical studies of the electropolymerization of o-phenylenediamine (OPD), m-toluidine (MT) and the copolymerization of OPD with MT are reported. Electropolymerization was performed in aqueous acidic medium at a constant potential of E SCE = 1.0 V at an indium doped tin oxide (ITO) coated glass electrode. The course of homopolymerization was followed for MT and OPD solutions with various monomer concentrations. The spectral characteristics of the mixed solutions were studied at a constant concentration of MT and various concentrations of OPD in the comonomer feed. An absorption band at λ = 497 nm was assigned to the head-to-tail mixed dimer/oligomer resulting from the cross reaction between OPD and MT cation radicals. UV–vis spectra recorded during copolymerization show dependence of the growth of the band at λ = 497 nm on OPD concentration in the feed. At lower OPD feed concentration it appears as the major band in the corresponding spectra. The UV–vis spectra recorded for the copolymer films suggest the incorporation of both monomer units in the copolymer. The FT-IR spectra of the copolymers show the presence of phenazine type structures in the copolymer backbone.

Binuclear and trinuclear complexes of exoO2-cyclam

Complexes of the ligand 2,3-dioxo-1,4,8,11-tetraaza-cyclotetradecane (exoO(2)-cyclam) have been prepared of formula [M(1){M(2)(exoO(2)-cyclam)}(2)][BPh(4)](2) where M(1)M(2) = CoCo (3), ZnZn (4), MnCu (5), FeCu (6), CoCu (7), NiCu (8), ZnCu (9), and [(bipy)(2)Ru{Cu(exoO(2)-cyclam)}][NO(3)](2) (10). Complex 10 crystallised in the space group C2/c and shows Jahn-Teller distorted Cu(II) with axial nitrate ligands. The {Cu(exoO(2)-cyclam)} moiety chelates to the Ru with Ru-O distances of 2.082(5) A. Complexes 5-10 show a Cu(II)/Cu(III) redox process and additional metal-centred (6, 8, 10) processes and ligand-centred (10) processes. The electrochemical and UV-Vis spectroelectrochemical study of suggested two closely-spaced oxidations based on the Cu and Ru centres which suggests that substituted derivatives of will be of interest for enhanced charge separation in dye-sensitised solar cells. Magnetic susceptibility measurements revealed dominant antiferromagnetic coupling within the trinuclear species 3, 5-8. Complex 10 showed Curie-Weiss behaviour with weak intermolecular interactions.

Development and characterization of flexible electrochromic devices based on polyaniline and poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid)

A flexible electrochromic device is reported by using polyaniline (PANI) doped with dl-camphor-10-sulfonic acid (CSA)/poly(styrene sulfonic acid) (PSS) as coloring electrodes and poly(ethylenedioxythiophene)-poly(styrene sulfonic acid) (PEDOT-PSS) as complementary electrodes. The characterizations of the devices were performed by using cyclic voltammetric and in situ UV–vis spectroelectrochemical studies. The devices demonstrates the color change from pale yellow (−0.5 V) to dark blue (+2.5 V). The improvement of optical properties, such as coloration efficiency and stability on the basis of PANI doped with PSS and PEDOT-PSS. Furthermore, the optical properties keep the same as the device is situated at the bending state.

Electrochromic devices based on copolymers of 3-Trimethoxysilanylpropyl-N-aniline-2,5-Dimethoxyaniline

Abstract Electrochemical copolymerization of 3-trimethoxysilanyl-propyl-N-aniline (TMSPA) with 2,5-dimethoxyaniline (DMA) was performed in 1 M HCl aqueous solution for different feed ratios of TMSPA using cyclic voltammetry. The deposition rate of TMSPA–DMA copolymer is higher than that of PTMSPA but lower than that of PDMA. (TMSPA-co-DMA) film was deposited using electrochemical polymerization as conducting film on indium tin oxide (ITO) electrode and used as an electrode in an electrochromic device. Poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) was spin-coated on ITO as the other electrode. Carboxyl-terminated- butadiene-acrylonitrile (CTBN) blended with LiClO4 was used as solid polymer electrolyte. A total solid electrochromic device was assembled as follows: ITO|P(TMSPA-co-DMA)∥LiClO4-CTBN∥PEDOT:PSS|ITO. The columbic efficiency of the devices reached to 104% for P(TMSPA-co-DMA) film with TMSPA feed ratio of 0.25. The optical contrast (ΔT, %) of the single electrode and the device were determined by UV–vis spectroelectrochemical studies. The stability of ΔT was improved during color switching from +1.5 to −1.5 V (vs. PEDOT) for this device. The device was pale yellow at −1.5 V and blue at +1.5 V.