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We report theoretical analysis on the geometries and electronic properties of new conjugated compounds based on thiazolothiazole synthesized by Ando et al. (Synth. Met., 156:327 [13]). The theoretical ground-state geometry and electronic structure of the studied molecules were investigated by the density functional theory (DFT) method at Becke’s three-parameter functional and Lee–Yang–Parr functional (B3LYP) level with 6-31G(d,p) basis set. The effects of the ring structure and the substituents on the geometries and electronic properties of these materials are discussed to investigate the relationship between molecular structure and optoelectronic properties. This investigation was used to drive further syntheses towards compounds more useful as active optoelectronic materials. Theoretical knowledge of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of the components is basic in studying organic solar cells, so the HOMO, LUMO, and gap energy V oc (open-circuit voltage) of the studied compounds are calculated and discussed. These properties suggest these materials as good candidates for use in organic dye-sensitized solar cells.

In this work the geometrical and electronic properties of (Carbazole-3.4-Ethylenedioxythiophene) (Cbz-Edot) based alternating donor-acceptor conjugated oligomers were studied by the density functional theory (DFT) at the B3LYP level with 6-31G(d) basis set. The acceptors investigated include thiazole (Z), thiadiazole (D), thienopyrazine (TP), thienothiadiazole (TD), benzothiadiazole (BT) and thiadiazolothienopyrazine (TPD). A low band gap will be expected in polymers containing donor-acceptor (D-A) repeating units. In order to predict the band gaps for guiding the synthesis of novel materials with low band gaps, we apply quantum-chemical techniques to calculate the band gaps in several oligomers. The results have been compared with those of thiophene and 3,4-ethylenedioxythiophene polymers with donor-acceptor fragment. The lowest excitation energies (Eex) and the maximal absorption wavelength (λabs) are studied using the time dependent density functional theory (TD-DFT), method. The electronic transitions of the absorption spectrum derived by TD-DFT method give useful structural and electronic information for designing novel conducting organic polymer materials. The theoretical results suggest that both the acceptor strength and the stable geometry contribute significantly to the electronic properties of alternating donor-acceptor conjugated copolymers. Copyright © 2012 VBRI press.

The inhibition effect of new heterocyclic compounds, namely N-(cyanomethyl)benzamide (BENZA) and N-[(1H-tetrazol-5-yl)methyl]benzamide (BENZA-TET), on mild steel corrosion 1 M HCl was investigated using electrochemical measurements. The results indicated that the inhibition efficiency depends on concentration, immersion time and temperature. The BENZA is a better inhibitor than BENZA-TET. Polarization measurements showed that the inhibitor BENZA-TET is a cathodic type, but BENZA acts as a mixed type inhibitor. In addition, the changes in impedance parameters indicated that these compounds adsorbed on the metal surface leading to the formation of a protective film. Adsorption of benzamide derivatives on the mild steel surface was investigated to consider basic information on the interaction between the inhibitors and the metal surface. It was found to obey the Langmuir adsorption isotherm. From the temperature dependence, the activation energy in the presence of (BENZA) was found to be inferior to that in uninhibited medium. In order to explain why BENZA is the most efficient inhibitor, quantum chemical calculations were applied. The relationships between quantum chemical parameters and corrosion inhibition efficiency have been discussed to see if there is any correlation between them.

Cancer is the worldwide health problem and the most frightening disease of humans. Modification of natural product lead is an important way to find promising anticancer agents. The β-carboline alkaloids present in medicinal plants have recently drawn attention due to their antitumor properties. Nine harmine derivatives (including harmine) were investigated for their antitumor effects and acute toxicities in mice, and the structure–activity relationship (SAR) was also analyzed by Qi Chen et al. In the present study, density functional theory calculations have been carried out in order to get insight into the structure and property information for this series of molecules. Descriptors such as total energy, gap energy, HOMO and LUMO energies, dipole moment (μ), electronegativity (χ), electron affinity (A), global hardness (η), softness (σ), and ionization potential (I), provide vital information about the activity of nine harmine derivatives. Further, we utilized our recently proposed model descriptor defined based on such calculated parameters to predict the antitumor activity/neurotoxicity of β-carboline alkaloids. Furthermore, satisfactory quantitative SAR models were derived to calculate the activities values from the DFT-computed electronic parameters.

Dans le but de contribuer a la valorisation de la flore marocaine en vue d’identifier de nouvelles substances potentiellement interessantes sur les plans biologique et therapeutique, nous avons procede a l’etude des huiles essentielles de la sciure de bois de Tetraclinis articulata (Vahl) Masters originaire de la region de Khemisset (Maroc). L’etude par CPG et CPG/SM de l’huile essentielle de sciure a permis d’identifier 22 constituants dont les cinq majoritaires sont: l’α-acorenol (20,9 %), le cedrol (17,9 %), le totarol (8,8 %), l’α-cedrene (8,7 %) et le β-acorenol (7,4 %). Par la suite, cette essence a ete fractionnee sur colonne ouverte de silice en utilisant un eluant de polarite croissante. Ainsi, cinq fractions ont ete recueillies. La fraction (FH) eluee avec le pentane est constituee d’hydrocarbures sesquiterpeniques, alors que les quatre fractions oxygenees (FO1 a FO4) eluees avec un melange diethyloxyde/pentane de polarite croissante sont dominees par un phenol diterpenique et deux alcools sesquiterpeniques respectivement: le totarol dans la fraction FO1 (42,4 %), l’α-acorenol dans les fractions FO2 (34,9 %) et FO3 (54,0 %), et le cedrol dans la fraction FO4 (58,2 %). L’huile de la sciure et ses fractions chromatographiques ont ete testees in vitro contre quatre bacteries: Escherichia coli, Bacillus subtilis, Staphylococcus aureus et Micrococcus luteus et trois champignons: Penicillium parasiticus, Aspergillus niger et Trametes pini. L’huile essentielle brute et les fractions oxygenees, notamment la FO1, constituee essentiellement du totarol, sont les plus actives. La fraction FO1 serait donc recommandee pour optimiser l’activite antimicrobienne de l’huile essentielle de Tetraclinis articulata.

Corrosion inhibition efficiencies of 1,4-dihydroquinoxaline-2,3-dione (Q1) and 2-phenylthieno[2,3-b]quinoxaline (Q2) as corrosion inhibitors against the corrosion of steel surface in hydrochloric acid is studied by means of density functional approach B3LYP/6-31G calculations. Quantum chemical parameters such as highest occupied molecular orbital energy (E HOMO), lowest unoccupied molecular orbital energy (E LUMO), energy gap (ΔE), dipole moment (μ), electronegativity (χ), electron affinity (A), global hardness (η), softness (σ), ionization potential (I), the fraction of electrons transferred (∆N), the global electrophilicity ω, and the total energy were calculated. All calculations have been performed by considering density functional theory using the GAUSSIAN03W suite of programs.

The inhibitive effect of 2-aminoquinoline-6-carboxylic acid (AQC) against mild steel corrosion in 1 M HCl solutions was investigated using conventional weight loss, potentiodynamic polarization, linear polarization and electrochemical impedance spectroscopy methods. The weight loss results showed that AQC is an excellent corrosion inhibitor since its efficiency increased with the concentration to attain 91.8 % at 500 mg l−1. Electrochemical polarization measurements revealed that AQC acted as a mixed-type inhibitor and the results of electrochemical impedance spectroscopy have shown that the change in the impedance parameters, charge transfer resistance and double layer capacitance, with the change in concentration of the inhibitor is due to the adsorption of the molecule leading to the formation of a protective layer on the surface of mild steel. The adsorption was assumed to occur on the steel surface through the active centers of the molecule. The inhibition action of AQC was discussed in view of Langmuir adsorption isotherm. Density functional theory calculations of quantum parameters were used to explain efficiency in relation with molecular structure.

In this part 3, The inhibitive effect of four substituted pyridazines, 5-[hydroxy(phenyl)methyl]-6-methylpyridazin-3(2H)-one (P1), 4-(2-chlorobenzyl)-6-hydrazino-3-methyl-1,6-dihydro pyridazine (P2), 5-(2,6-dichlorobenzyl)-6-methylpyridazin-3(2H)-one (P3) and 5-[(2-chlorophenyl) (hydroxy)methyl]-6-methyl pyridazin-3(2H)-one (P4) against the copper corrosion in nitric acid solution is investigated using density functional approach B3LYP/6-31G* calculations. Results obtained by weight loss and polarization measurements in part 1 show that P1, P3, and P4 are the best inhibitors. The kinetic and adsorption parameters obtained in part 2 indicated that pyridazine acted preferentially by physical adsorption. The calculated quantum chemical parameters are the highest occupied molecular orbital, the lowest unoccupied molecular orbital, the separation energy, dipole moment, electronegativity, electron affinity, global hardness, softness, ionization potential, the fraction of electrons transferred, and the total energy. The obtained data are discussed according to the inhibition efficiencies obtained.

The inhibition of the corrosion of mild steel 1 M HCl solution by some diamine compounds has been investigated in relation to the concentration of the inhibitor as well as the temperature using weight loss and electrochemical measurements. The effect of the temperature on the corrosion behavior with the addition of different concentrations of new diamine compounds (3-[2-(2-cyano-ethylamino)-methylamino]-propionitrile (P1); 3-[2-(2-cyano-ethylamino)-ethylamino]-propionitrile (P2), and 3-[6-(2-cyano-ethylamino)-hexylamino]-propionitrile (P3), respectively, was studied in the temperature range 40–80 °C. Polarization curves reveal that (P1, P2, and P3) are mixed type inhibitors. The inhibition efficiency of organic compounds is temperature independent, but increases with the inhibitor concentration. Adsorption of inhibitor on the carbon steel surface is found to obey the Langmuir adsorption isotherm. Some thermodynamic functions of dissolution and adsorption processes were also determined. On the other hand, and in order to determine the relationship between the molecular structure of these compounds and inhibition efficiency, quantum chemical parameters were calculated. The theoretically obtained results were found to be consistent with the experimental data.

In this work, we investigate oligopyrroles and derivatives, which serve as models for corresponding polymers. In order to discuss these materials, we carried out DFT calculations and used DFT methods to calculate ground state electronic structures. We are particularly interested in exploring the potential of several substituent groups as electron donors with numerous ties to electronic materials by exploring and comparing the energies of HOMO, LUMO, Gap energies, and structural properties. Results are discussed in comparison with the properties of the doped oligomers. The theoretical ground-state geometry and electronic structure of the studied molecules were obtained by the DFT method at B3LYP level with 6-31G(d) basis set. The opto-electronic properties of these materials were determined by ZINDO/s and TD//B3LYP/6-31G(d) calculations performed on the B3LYP/6-31(d) optimized geometries. The results of this study demonstrate how electronic properties can be tuned by the backbone ring or side group and suggest these compounds as good candidates for opto-electronic applications.

Organic conjugated polymers based on heterocylic ring exhibit semiconducting properties associated with the π molecular orbitals delocalized along the polymer chains. These materials have attracted much interest for potential applications in optoelectronic devices due to their unique electronic and photonic properties. Recently, interesting studies have been devoted to the synthesis, characterization, physical and chemical properties and variety of these materials. In this work, a quantum- chemical investigation on the structural and opto-electronic properties of new polymer named poly (4-methylythioazole-2.5- diyl)s is carried out. We present a detailed DFT study of geometrical structures and electronic properties of this organic material. Calculated results are compared with experimental data and based on such comparison we try first, to propose an oligomer model and then, to obtain a qualitative understanding the properties of polymer. We discuss the influence of chain length on structural and optoelectronic properties. The numerical predictions are compared to our experimental results. The ground state optimized structures and energies are obtained using the molecular orbital theory and the DFT (B3LYP/6-31G (d)) calculations. Copyright © 2011 VBRI press.

Inhibition of corrosion of copper in 2M HNO3 by N-1-naphthylethylenediamine dihydrochloride monomethanolate (N-NEDHME) has been studied by use of weight loss, electrochemical polarization, and electrochemical impedance spectroscopy (EIS) measurements. The result obtained reveal that this organic compound is a very good inhibitor and its inhibition efficiency increases with increasing concentration, reaching 94% at 10−3 M at 303 K. The potentiodynamic polarization study indicated that this compound acts as a cathodic type corrosion inhibitor. EIS results indicate that the change in the impedance properties (Rt and Cdl) with concentration of inhibitor was because of the formation of a protective layer on the surface of copper. Quantum chemical calculations using DFT at the B3LYP/6-31G* level of theory was further used to calculate some electronic properties of the molecule in order to ascertain any correlation between the inhibitive effect and molecular structure of N-NEDHME. The effect of temperature between 303 and 343 K and calculation of activation data will be discussed in Part 2.

International audience; Via the procedure of oxidative coupling of furan monomers using either titanium tetrachloride (TiCl4) or ferric chloride (FeCl3) as oxidants, two different compounds are obtained. Different experimental analyses including infrared, Raman, optical absorption and ESR techniques are combined and completed by density functional theory to differentiate between both resulting compounds. It is found that both oxidants induce cleavage of aromatic rings. The rates of the resulting aliphatic sequences in each compound are different. Then, to elucidate the effect of oxidant on the electronic properties of the resulting compounds, an ESR dependant temperature study is done. We show that the compound obtained by using FeCl3 contains ionic structure. The effect of temperature on the dynamics of these electronic species is also studied.

International audience; Thienylene–dialkoxyphenylene copolymers with polar side chains are soluble in most organic solvents and exhibit excellent glass adhesion properties, allowing the formation of homogeneous thin films on glass, quartz, and other substrates by spin coating. The electrochemical and optical properties of thin films of this material are studied in this work. The calculated band gap derived from electrochemical data (2.34 eV) is in good agreement with that observed from the UV–vis spectrum edge (2.25 eV). The analysis of the emission properties reveals the strong dependence on temperature of the electron coupling with different vibrational modes in the formation of the vibronic bands.

The organic conducting polymers are some of the most promising materials for optoelectronic device technology. In this paper we present a combined experimental and theoretical study of the structure, optical and spectroscopic properties of a new copolymer based on 3,4-ethylene dioxythiophene (EDOT) and poly(N-vinylcarbazole) (PVK). This copolymer was prepared by oxidative copolymerization. In order to predict the unknown properties of our prepared copolymer, DFT quantum chemical calculations on the structure and electronic and spectroscopic properties were performed and compared with experimental results.

Conjugated polymers containing carbazole moieties either in the main or in the side chains have attracted much attention because of their unique electronic properties, to their high photoluminescence quantum efficiency, and thermal stability. The aim of this work is to study a new organic copolymer which combines the PVK properties and those of PHT. We will describe in this study the protocol synthesis, the chemical structure, and the electronic and vibrational properties of the resulting copolymer. The experimental and theoretical studies are combined in order to describe the properties of this material. These properties suggest this compound (PVK-PHT) to be a good candidate for optoelectronic application.

A quantum-chemical investigation on the structural and optoelectronic properties of two materials based on carbazole is carried out. The purpose is to display the effect of grafting the fluorine atoms on their optoelectronic and physico-chemical properties. In addition to solubility in the polar solvents and the modification in geometric parameters, the substitution of fluorine destabilizes the HOMO and LUMO levels, decreases the band gap energy and raises conjugation length. These properties suggest the substituted fluorine compound as a good candidate for optoelectronic applications.

In this paper, we report on a theoretical study of structural and electronic properties of some oligothiophenes based on cylopentadithiophene (CPDT) dimers in which both 3,3′ positions were bridged with (CH2, SiH2, C(CN)2, S, C O, C S, C CH2, and C C(CN)2). The important reduction of the gap energy observed for the whole series of the bridged compounds studied here, is explained on the basis of an orbital interaction analysis. Computations were performed by using density functional theory (DFT) calculations. The compounds bridged by C S and C C(CN)2 have small Eg = LUMO–HOMO gaps suggesting that these compounds have optoelectronic application.

In this work, a quantum–chemical investigation on the structural and opto-electronic properties of oligo(thiophene-phenylene) (4TP) is carried out. The results are discussed in comparison with the properties of corresponding oligothiophene (8T) and oligophenylene (8P). As the opto-electronic properties of this type of conducting polymers are governed by their electronic band gap, we shall also present a comparison among HOMO, LUMO and band gap energies of these three materials.

In this work, a combination of experimental and theoretical study of Polyfuran and its oligomers, in their neutral and doped states, was reported. The effect of chain length on optoelectronic properties was discussed using the Density Functional Theory (DFT). Since the opto-electronic properties of this kind of conducting polymers are governed by their band gap, a comparison among Highest Occupied Molecular Orbital, Last Unoccupied Molecular Orbital and band Gap energies of these compounds shall be presented.

A quantum-chemical investigation on the structural and opto-electronic properties of several alkoxy substituted 4,4'-bis(2-phenylethenyl)biphenyls (PEBP) as building blocks for π-conjugate polymer is performed in order to display the effect of changing the position of alkoxy substituents on the peripheral phenyl rings on their opto-electronic and physico-chemical properties. Added to the good agreement between theoretical and experimental observations, it has been observed that the substitution effect depends on the position of the methoxy group: in ortho- or para-positions it acts as a mesomeric electrons donor, while as an inductive electrons acceptor in meta-positions. Substitution in ortho-positions causes significant structural deformations of PEBP backbone due to the steric interaction between the substituents and the hydrogens of the vinylene functions. Bridging of ortho, para-PEBP (24PEBP) by C=C(CN) 2 decreases significantly its band gap. This model can have very interesting opto-electronic ownerships.

In this paper, we report a theoretical study of oligothiophenes (from the dimer to the octamer) in their neutral and oxidized states based on DFT (B3LYP/6-31G*) calculations and focusing the discussion on the influence of chain length on conformational and optoelectronic properties. The bridging effect by CH 2 , SiH 2 , C O and C C(CN) 2 on the optoelectronic properties of the octamer will then be investigated. The obtained results are close to available experimental ones. While structural parameters of neutral oligomers do not change significantly, the oligomers become planar and show a quinoidal character after oxidation. The bridging by C C(CN) 2 significantly decreases the octamer's band gap.

We present a DFT study of conformational and optoelectronic properties of the oligo-para-phenylenes from the dimer to the octamer in their neutral and doped states. Conformational analysis shows that there are no big changes in the torsional angles of the oligomers in their neutral form. When they are doped the oligomer structures are completely planar. The opto-electronic properties of the octamer lead us to suggest that this oligomer is a good model to reflect those of the parent polymer.

Six new co-polymers based on thiophene and phenylene, prepared by Stille coupling reactions, were synthesized and characterized. The polymerization degrees of the different co-polymers are estimated by Gel permeation chromatography (GPC). The infrared and Raman scattering results confirm the proposed structures. The UV–vis results show that the absorption maximum ( λ max ) values are sufficient to consider applications of these co-polymers in the opto-electronic field.

A series of novel soluble conjugated regioregular copolymers (poly(2,5-dialkoxy-p-phenylene thienylenes)) was prepared via palladium-catalyzed Stille coupling reactions. The attachment of ethylene oxide chains to the phenylene rings ((OCH2CH2)nOR; n = 2, R = Me; n = 2, R = Bu; n = 3, R = Me) provided to the polymer increased solubility in polar solvents improved adhesion properties on glass substrates and complexing properties towards lithium ions. The structure of the polymers was established by FTIR, 1H and 13C NMR spectroscopy and elemental analysis. The physical properties were studied by X-ray diffraction, cyclic voltammetry, UV–Vis absorption and fluorescence, and Raman spectroscopy. The electrochemical properties of the copolymers compare favorably to those of the active materials used in electro-optical devices such as LED, LEC and electrochromic devices. Compared to related phenylene–thienylene copolymers the reported new materials showed lower values of the band gap and of the oxidation potential which is indicative of a highly conjugated π-system.

A thienylene-dialkoxyphenylene copolymer was prepared by condensation between a bis-stannylthiophene reagent and a substituted dibromobenzene derivative in the presence of a palladium catalyst. Owing to the presence of 2-(2-butoxy-ethoxy)-ethoxy polar side chains the polymer was soluble in most organic solvents and exhibited excellent glass adhesion properties. It allowed the formation of homogeneous thin films on indium tin oxide (ITO) by spin coating. The electrochemical and optical properties of thin films of the material have been studied. The calculated band gap derived from cyclic voltammetry data (2.21 eV) is in good agreement with the one calculated from the UV–VIS spectrum edge ( 2.15 eV). A single layer light emitting diode (LED) was fabricated in the configuration of ITO/polymer/Al. Electroluminescent maximum was recorded at 600 nm corresponding to a red orange emission. The diode exhibited an operating voltage at ca. 5 V and a high current rectification ratio (3×10 3 ).

Polyfuran constitutes polymer belong the conjugated systems which have been pointed out functionalized properties in the electronic and optic fields. In the present paper, experiment and theoretical analysis on Polyfuran with his oligomers have been reported. The interpretation of the infrared and Raman spectra of Polyfuran is presented. In order to discuss the functional properties of oligofurans, we used Density Functional Theory methods and carried out DFT calculations to determinate their electronic, electrochemical and absorption properties. The efficient low band gap allows furan-based polymers to be promising organic materials in photovoltaic application, also the oxygen-based conjugated materials constitute more biodegradable conducting compounds especially for solar cells compared to Sulfur or Selenium.

Two types of conjugated copolymers functionalized by chelating subunits were prepared using the palladium catalysed coupling reaction of a dihalogenated substrate containing a coordinating unit and a bis(tributylstannyl) conjugated reagent. The ionochromic properties of the polymers containing crown ethers or bipyridine were studied.

Oxidative coupling of silyl monomers containing phenylene units was performed electrochemically and chemically using FeCl3 as oxidant. 2,5-Trimethylsilyl-1,4-dihexoxybenzene led to poly (2,5-dihexoxyparaphenylene) with a degree of polymerization higher than the one obtained upon oxdative coupling of non silyl monomers. The coupling reaction was however moderately improved in the case of 3,6-bis-dimethylsilyl(N-n-butylcarbazole). The role of the silyl substituents during the oxidative polymerization is dicussed.

Deux approches basees sur la chimie organometallique permettant de controler la regularite des enchainements en serie thiophenique sont analysees: (i) l'activation par les groupements SiMe 3 du couplage oxydant, (ii) le couplage organometallique catalyse par un complexe de Pd° d'un derive de l'etain et d'un halogenure aromatique.

Novel ten organic donor-π-acceptor dyes (D-π-A), used for dye-sensitized solar cells (DSSCs), based on thiazolothiazole were studied by density functional theory (DFT) and time dependant DFT (TDDFT) approaches to shed light on how the π-conjugation order influence the performance of the dyes. The electron acceptor (anchoring) group was 2-cyanoacrylic for all dyes whereas the electron-donor unit varied and the influence was investigated. The theoretical results have shown that TDDFT calculations using the Coulomb attenuating method CAM-B3LYP with the polarized split-valence 6-31G (d,p) basis sets and the polarizable continuum model (PCM) were reasonably capable of predicting the excitation energies, the absorption and the emission spectra of the molecules. The LUMO and HOMO energy levels of these dyes can ensure a positive effect on the process of electron injection and dye regeneration. The trend of the calculated HOMO-LUMO gaps nicely compares with the spectral data. Key parameters in close connection with the short-circuit current density (Jsc), including light-harvesting efficiency (LHE), injection driving force (ΔG(inject)) and total reorganization energy (λtotal), were discussed. In addition, the estimated values of open-circuit photovoltage (Voc) for these dyes were presented. The calculated results of these dyes reveal that the D6 dye can be used as a potential sensitizer for TiO2 nanocrystalline solar cells due to its best electronic and optical properties and good photovoltaic parameters.

A variety of organic donor–acceptor–donor materials based on thienylbenzothiadiazole (BTD[Formula: see text]–5) combined with different [Formula: see text]-conjugated systems are studied by density functional theory (DFT) and time-dependent DFT (TD-DFT) for the ground- and excited-state properties, respectively, using B3LYP and the 6-31G(d, p) basis set. The effect of different electron-donor groups on the structural, electronic and optoelectronic properties is studied. To provide for the bandgap and to guide the synthesis of novel low bandgap materials, we applied quantum chemistry techniques to calculate the difference in the highest occupied molecular orbital (HOMO) and lowest occupied molecular orbital LUMO energies. However, we have studied the effect of the reduction and oxidation properties on the electronic excitation transitions for all compounds. The emission energies have been obtained from TD-DFT calculations performed on the excited-state optimized S1 geometries. The theoretical results suggest that both the introduction of electron-donor groups and the doping process contribute significantly to the electronic and optoelectronic properties of the alternating donor–acceptor–donor conjugated systems studied.

International audience; A study of the structure, electronic, and optical properties of oligothiophenes is reported. Geometry optimizations of the ground state of derivatives of these molecules were carried out using the density functional theory (DFT) with the B3LYP functional and the 6-31G(d) basis set. Bridged oligothiophenes by C═O, C═S, and C═C(CN)2 functional groups were found to be planar in their electronic ground states (S0). The electronic excitation transitions of the bridged oligothiophenes were investigated using the time-dependent TD-DFT method performed on the ground-state optimized geometries. For all the derivatives, excitation to the S1 state corresponds mainly to the HOMO → LUMO transition. The excitation energies are found in fair agreement with the experimental values. The optimization (relaxation) of the first singlet excited electronic state (S1) has been done using the restricted configuration interaction (singles) (RCIS/6-31G(d) approach. The electronically excited geometries favor a more quinoidic type structure. Emission energies have been obtained from TD-DFT calculations performed on the excited-state optimized geometries S1. The change of group (C═O, C═S, and C═C(CN)2) as well as the incorporation of monomer moieties induce a significant decrease in the excitation and emission energies.

International audience; In this paper, we report the synthesis and characterization of a new material based on Poly(N-vinylcarbazole) (PVK) and Poly(3-methylthiophene) (PMeT), which has been chemically prepared by cross-linking of PVK in the presence of 3-methylthiophene monomers in chloroform with anhydrous FeCl3. Thus, two samples were prepared, PVK-3MeT1 and PVK-3MeT2, obtained firstly in the fully doped state and successfully dedoped by chemical treatment. They were characterized by various spectroscopic methods as well as thermal analysis and conductivity measurements. Then, the formation of PMeT by oxidative coupling and its grafting into the skeleton of PVK is shown. Furthermore, the optical analysis shows that the new materials exhibit a blue-shift compared to that of the PMeT homo-polymer. The obtained graft copolymer presents interesting optical and thermal properties compared to that of the homo-polymers.

Poly(para-hydroquinone) (PPHQ) was prepared by chemical oxidation reaction using titanium tetrachloride (TiCl4) as an oxidant. Solid-state nuclear magnetic resonance (CPMAS 13C-NMR), infrared absorption, optical absorption, thermal analysis (TGA and DTA), and electron paramagnetic resonance techniques were used to characterize the obtained PPHQ polymer. The correlation between different experimental results justifies the chemical structure and proves the vibrational and optical properties of this polymer. Theoretical calculations based on ab initio density functional theory and semiempirical Austin Model 1 methods were accomplished to elucidate the structure–property relationship of PPHQ polymer. From oligomer 8-hydroquinone, we have predicted the experimentally observed results. This oligomer is considered as model structure, which reproduces the PPHQ polymer characteristics and elucidates the TiCl4 effect on the properties of the polymer under study. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

This paper reports on the optical studies of the thin film of one thienylene–dialkoxyphenylene copolymer. The film for the optical measurements was prepared by spin coating on glass substrates. Absorption spectra were recorded at room temperature and photoluminescence spectra were recorded in the temperature range from 300 K to 20 K. The analysis of the relative intensity of the zero-phonon, and the 0–1 and 0–2 vibronic bands indicates a change in conjugation length with temperature in the PL spectra, and its evolution allows the determination of the Huang–Rhys factor.

P3mt1 and P3mt2 were electrochemically synthesized using two different electrolyte supports H2SO4 and TEABF4, respectively. First, it was deduced from density functional theory (DFT) calculations that the electronic and steric effects govern polymerization mechanism of the radical monomers. Second, DFT combined with experimental spectroscopic analyses (ESR, Infrared, Raman, and 13C NMR) demonstrate that H2SO4 or TEABF4 could generate a homogenous or heterogeneous coupling site, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 57–64, 2006

Structure–olfactive threshold relationships for 40 pyrazine derivatives have been studied by multivariate statistical analysis. Variable descriptors used to describe the molecules studied were obtained using molecular-mechanics software. A correlation coefficient of 0.82 was obtained when all the molecules were included in the model. When the model was established for closely related subsets of molecules, the correlation coefficients obtained were higher and the established models were bilinear. Such models allow the identification of optimal structures corresponding to low olfactive thresholds for the subsets studied. Surprisingly, we find that the optimum structures are included in the set of 40 molecules. The efficiency of the models was supported by the cross-validation technique, where the correlation coefficients were found to be good with respect to the precision of the values of the olfactive thresholds.

The role of silyl substituents in the anodic polymerization of thiophene has been studied. The oxidative polymerization reaction is activated by the presence of trimethylsilyl groups. In order to obtain polymer of high molecular weight and low polydispersity, two such trimethylsilyl substituents in the 2,5-positions of the thiophene ring were found to be necessary.

This work reports a theoretical investigation of π-conjugated oligomers constituted by n units ( n = 1-4) based on carbazole and ethylenedioxythiophene. The molecular geometry, torsional potential, electronic and optical properties of the oligomers [Cbz-(Edot) n -Cbz] ( n = 1-4) are investigated using DFT (B3LYP/3-21G*) calculations. The discussion is focused on the influence of chain length on the properties of these copolymers. The analyses of torsional angles for [Cbz-(Edot) 4 -Cbz] reveal that the structure has a anti-planar conformation. The electronic properties of the molecules, HOMO, LUMO and E g (HOMO-LUMO), are studied using B3LYP functional. The results have been compared with those of thiophene and ethylenedioxythiophene. The lowest excitation energies (E ex ) and the maximal absorption wavelength (λ abs ) are studied using the TD/DFT, ZINDO and CIS methods. The electronic transitions of the absorption spectrum derived by TD/DFT method give useful structural and electronic information for designing novel conducting organic polymer materials. The bridging effect by C=C(CN) 2 on the optoelectronic properties of the (carbazole-thiophene-carbazole) comonomer is investigated. Keywords : Conducting polymer; Carbazole-(Ethylenedioxythiophene) n -Carbazole comonomers; DFT Optoelectronic properties; absorption coefficient; Bridging effect. © 2012 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. doi: http://dx.doi.org/10.3329/jsr.v4i1.7450 J. Sci. Res. 4 (1), 119-133 (2012)

The oxidative polymerization of a variety of silylmonomers was performed. Applications and limits of this methodology are presented.

To establish a quantitative structure–activity relationship for non-competitive antagonists of the N -methyl- d -aspartate receptor, 48 substituted dibenzo[ a , d ]cycloalkenimine derivatives were analyzed by principal components, a descendant multiple regression analyses, multiple non-linear regression and an artificial neural network. We propose non-linear and linear quantitative structure–activity models and interpret the activity of the compounds by the multivariate statistical analysis. Density functional theory with Becke's three-parameter hybrid function and Lee–Yang–Parr exchange correlation functional calculations were performed to define the structure, chemical reactivity and properties of the study compounds. The topological and the electronic descriptors were computed with ACD/ChemSketch and Gaussian 03W programs, respectively. The study shows that multiple regression and multiple non-linear regression analyses predict activity; however, predictions made with a 6-2-1 artificial neural network model were more accurate. This model gave statistically significant results and showed good stability to data variation in leave-one-out cross-validation.

A study of structure–activity relationship (QSAR) was performed on a set of 30 coumarin-based molecules. This study was performed using multiple linear regressions (MLRs) and an artificial neural network (ANN). The predicted values of the antioxidant activities of coumarins were in good agreement with the experimental results. Several statistical criteria, such as the mean square error (MSE) and the correlation coefficient (R), were studied to evaluate the developed models. The best results were obtained with a network architecture [8-4-1] (R = 0.908, MSE = 0.032), activation functions (tansig–purelin) and the Levenberg–Marquardt learning algorithm. The model proposed in this study consists of large electronic descriptors that are used to describe these molecules. The results suggested that the proposed combination of calculated parameters may be useful for predicting the antioxidant activities of coumarin derivatives.