bluuebunny/crossref_metadata_2025_split huggingface dataset:
Conformational analysis of trans‐2‐halocyclohexanols and their methyl ethers: a 1H NMR, theoretical and solvation approach
Authors: Freitas M. P. , Tormena C. F. , Rittner R. , Abraham R. J. 
Published: December 2002

AbstractThe conformational equilibria of trans‐1‐methoxy‐2‐chloro‐ (1), trans‐1‐methoxy‐2‐bromo‐ (2) and trans‐1‐methoxy‐2‐iodocyclohexane (3), and their corresponding alcohols (4–6), were studied through a combined method of NMR, theoretical calculations and solvation theory. They can be described in terms of the axial–axial and equatorial–equatorial conformations, taking into account the main rotamers of each of these conformations. From the NMR experiments at 183 K in CD2Cl2–CS2, it was possible to observe proton H2 in the ax–ax and eq–eq conformers separately for 1 and 2, but not for 3, which gave directly their populations and conformer energies. In the alcohols the proportion of the ax–ax conformer was too low to be detected by NMR under these conditions. Those HH couplings together with the values at room temperature, in a variety of solvents allowed the determination of the solvent dependence of the conformer energies and hence the vapor state energy difference. The ΔE (Eax–Eeq) values in the vapor state for 1, 2 and 3 are −0.05, 0.20 and 0.55 kcal mol−1, respectively, increasing to 1.10, 1.22 and 1.41 kcal mol−1 in CD3CN solution (1 kcal = 4.184 kJ). For 4–6 the eq–eq conformation is always much more stable in both non‐polar and polar solvents, with energy differences ranging from 1.78, 1.94 and 1.86 kcal mol−1 (in CCl4) to 1.27, 1.49 and 1.54 kcal mol−1 (in DMSO), respectively. Comparison of the hydroxy and methoxy compounds gives the intramolecular hydrogen bonding energy for the alcohols as 1.40, 1.36 and 1.00 kcal mol−1 (in CCl4) for 4, 5 and 6, respectively. Copyright © 2002 John Wiley & Sons, Ltd.
Ab initio studies of the bromination of benzene
Authors: Smith William B. 
Published: December 2002

AbstractThe reaction of elemental bromine with benzene was followed using ab initio modeling. Two mechanisms were considered as possibilities based in part on tradition and in part on more current experimental evidence. Consideration of transition state energy rules against the conventional picture involving direct formation of the Wheland intermediate via electrophilic attack by bromine. The preferred pathway is calculated to be through the cation–anion radical pair which then goes to the Wheland intermediate. Copyright © 2002 John Wiley & Sons, Ltd.
Kinetics and mechanisms of the gas‐phase elimination of arylethyl N,N‐dimethylcarbamates and ω‐phenylalkyl N,N‐dimethylcarbamates
Authors: Chuchani Gabriel , Dominguez Rosa M. , Rotinov Alexandra , Herize Armando 
Published: December 2002

AbstractThe gas‐phase elimination kinetics of several arylethyl N,N‐dimethylcarbamates and ω‐phenylalkyl N,N‐dimethylcarbamates were determined in the temperature range 299.6–399.9 °C and pressure range 18–95 Torr. The reactions in a static system, seasoned with allyl bromide, and in the presence of a free radical suppressor are homogeneous and unimolecular and follow a first‐order rate law. The rate coefficients are given by the Arrhenius equations: for 4‐phenethyl N,N‐dimethylcarbamate, log[k1 (s−1)] = (11.32 ± 0.22) −(166.9 ± 2.5) kJ mol−1 (2.303RT)−1; for methylphenethyl N,N‐dimethylcarbamate, log[k1 (s−1)] = (12.07 ± 0.36) −(178.6 ± 4.3) kJ mol−1 (2.303RT)−1; for 4‐methoxyphenethyl N,N‐dimethylcarbamate, log[k1 (s−1)] = (11.03 ± 0.60) −(167.3 ± 7.1)­kJ mol−1 (2.303RT)−1; for 4‐nitrophenethyl N,N‐dimethylcarbamate, log[k1 (s−1)] = (11.31 ± 0.54) −(163.7 ±­6.1) kJ mol−1 (2.303RT)−1; for 3‐(4‐methoxyphenyl)propyl N,N‐dimethylcarbamate, log[k1 (s−1)] =­(13.52 ± 0.54) −(208.4 ± 6.8) kJ mol−1 (2.303 RT)−1; for 4‐phenyl‐1‐butyl N,N‐dimethylcarbamate, log[k1 (s−1)] = (12.00 ± 0.34) −(185.2 ± 4.2) kJ mol−1 (2.303 RT)−1; and for 5‐phenyl‐1‐pentyl N,N‐dimethyl carbamate, log[k1 (s−1)] = (11.79 ± 0.31) −(182.2 ± 3.9) kJ mol−1 (2.303RT)−1. The results imply the absence of anchimeric assistance of the phenyl group, while the acidity of the benzylic β‐hydrogen appears to be responsible for a small but significant rate augmentation in these eliminations. Copyright © 2002 John Wiley & Sons, Ltd.
Mechanism of elimination of amino acid derivatives in the gas phase. Pyrolysis kinetics of ethyl picolinate, ethyl 1‐methylpipecolinate and picolinic acid
Authors: Lafont Jennifer , Ensuncho Adolfo , Domínguez Rosa M. , Rotinov Alexandra , Herize Armando , Quijano Jairo , Chuchani Gabriel 
Published: December 2002

AbstractThe kinetics of the gas‐phase elimination of the title compounds were determined in a static reaction system over the temperature range 180.8–419.4 °C and the pressure range 15–86 Torr (1 Torr = 133.3 Pa). The reactions are homogeneous and unimolecular and obey a first‐order rate law. The observed rate coefficients are represented by the following Arrhenius equations: for ethyl picolinate, log[k1(s−1)] = (11.30 ± 0.24) −(180.9 ±­3.0) kJ mol−1 (2.303 RT)−1, for ethyl 1‐methylpipecolinate, log[k1(s−1)] = (13.36 ± 0.31) −(209.5 ± 3.9) kJ mol−1 (2.303 RT)−1 and for picolinic acid, log[k1(s−1)] = (12.05 ± 0.10) −(135.7 ± 0.9) kJ mol−1 (2.303 RT)−1. The data from this work together with those reported in the literature confirm previous considerations that amino acids or α‐nitrogen substituents of carboxylic acids undergo an extremely rapid decarboxylation process. The pyrolysis kinetics of picolinic acid, which is an intermediate of ethyl picolinate elimination, showed a dramatic fast decomposition into pyridine and CO2 gas. The decarboxylation process of α‐amino or α‐nitrogen substituents of carboxylic acids differs from the decarbonylation elimination of several known α‐substituted carboxylic acids in the gas phase. Copyright © 2002 John Wiley & Sons, Ltd.
Intramolecular proton transfer in tautomeric 2‐Imidazolone and 2‐thioimidazolone
Authors: Contreras J. Guillermo , Madariaga Sandra T. 
Published: December 2002

AbstractThe enol ⇌ keto and thiol ⇌ thione prototropic tautomerisms in 2‐imidazolone and 2‐thioimidazolone were studied by ab initio methods in the frame of MO theory. The energetics of these reactions were derived using various basis sets and levels including both polarization and diffuse functions. To account for electron correlation, second‐, third‐ and fourth‐order Møller–Plesset perturbation theory was applied. The thermodynamics for both reactions indicate that the keto and thione are the predominant species in the gas phase, whereas in solution the enol and keto forms are present in comparable concentrations. For both tautomerization reactions the transition states for the intramolecular mechanism were found and fully characterized. The calculated energetic barrier for the enol–keto system is 41.6 kcal mol−1, whereas that for the thiol–thione system is 32.5 kcal mol−1 (1 kcal = 4.184 kJ). The study of the solvent effect, using the PCM model, on Ea reveals that solvents lower the barrier by ca 11 and 7 kcal mol−1 for the enol–keto and thiol–thione systems, respectively. Copyright © 2002 John Wiley & Sons, Ltd.
Structural properties and 13C chemical shifts of bis‐ and tris(2‐thienyl)methinium and related cations: a combined theoretical and experimental study
Authors: Fabian Jürgen , Hartmann Horst , Noack Antje 
Published: December 2002

AbstractThe molecular structure of the parent bis‐ and tris(2‐thienyl)methinium ions were studied by first‐principles methods (second‐order Møller–Plesset many‐body perturbation theory and density functional theory). In contrast to bis(2‐thienyl)methinium, tris(2‐thienyl)methinium is non‐planar with torsion angles between the thienyl groups and the central plane of about 30°. The calculations on tris(2‐thienyl)methinium resulted in two almost isoenergetic conformers with barriers to isomerization less than 10 kcal mol−1 (1 kcal = 4.184 kJ). In order to discuss the 13C chemical shifts of Crystal Violet and of heteroanalogous compounds with thienyl‐2‐, with 5‐amino‐thienyl‐2‐, with 5‐methylmercapto‐thienyl‐2‐ and with 5‐amino‐1,3‐thiazolyl‐2‐heteroaryl groups, the structure was optimized at the DFT B3‐LYP/6–31G(d) level and the chemical shifts were calculated at the DFT‐GIAO/6–311 + G(2d,p) level of theory. In general, the experimental chemical shifts correlate very well with the experimental values. The lowest energy electronic transitions in the UV–VIS region were calculated by time‐dependent density functional response theory (TD‐DFRT) using the DFT B3‐LYP/6–31 + G(d) basis set. For cationic dyes the agreement between the results of TD‐DFRT calculations and experiment was less good than for neutral sulfur‐containing compounds. Semiempirical calculations (PPP, ZINDO/S) are better in that case and are more efficient. Copyright © 2002 Wiley & Sons, Ltd.
Quantitative approach to the Menschutkin reaction of benzylic systems
Authors: Yoh Soo‐Dong , Cheong Duk‐Young , Lee Oh‐Seuk 
Published: December 2002

AbstractThe quaternization reactions of substituted (Z)‐benzyl (X)‐benzenesulfonates with substituted (Y)‐pyridines were investigated in acetonitrile at 35 °C. The magnitudes of the Hammett reaction constants ρX, ρY and ρZ indicate that a stronger nucleophile leads to a lesser degree of bond breaking. In addition, a better leaving group is accompanied by a lesser degree of bond formation. Application of multi‐Hammett interactions, |ρYZ | >|ρXY | >|ρXZ |, predicts that these Menschutkin‐type reactions are dissociative SN2 reactions. In particular, the reaction of strongly activated benzyl derivatives with tertiary amines in acetonitrile reveals a more advanced bond breaking like SN1 reactions. The predicted mechanism for the benzylation of pyridines with benzylic systems is evident from More O'Ferrall–Jencks diagram and the semi‐empirical MO calculations with the AM1 method. Copyright © 2002 John Wiley & Sons, Ltd.
Photophysical and photochemical properties of 5,7‐dimethoxycoumarin under one‐ and two‐photon excitation
Authors: Belfield Kevin D. , Bondar Mykhailo V. , Liu Yong , Przhonska Olga V. 
Published: December 2002

AbstractThe spectroscopic and photochemical properties of 5,7‐dimethoxycoumarin (DMC) in acetonitrile (ACN) were investigated at room temperature under one‐ and two‐photon excitation. Two‐photon induced [2 + 2] photocycloaddition of DMC was investigated with 650 nm laser excitation (120 fs pulse width). GC and GC–MS analysis confirmed dimer formation, while HPLC analysis allowed specific photodimer identification through comparison with samples prepared via one photon irradiation. Photodimer products formed via two‐photon excitation correlated with those formed via UV irradiation. Syn head‐to‐head and syn head‐to‐tail photodimers were formed in 1:3.0 and 1:2.8 ratios under one‐photon (broadband UV) and two‐photon (650 nm, 120 fs) irradiation in anisole, respectively. The quantum yield for the photoreaction of DMC solution (10−4 M) under broadband UV irradiation was of the order of 1 × 10−3 and increased dramatically to 1 × 10−2 under two‐photon excitation. The spectral investigation of the photochemical products of DMC revealed efficient fluorescence emission in the spectral region 290–340 nm, attributed to the syn‐head‐to‐tail dimers of DMC. Evidence for an additional manifold for the photochemical reaction of DMC was found, resulting in the production of photochemical products that exhibited low fluorescence emission intensity along with dependences on excitation wavelength. Copyright © 2002 John Wiley & Sons, Ltd.
Gas‐phase Diels–Alder cycloaddition reaction in the presence of methanol and water vapor
Authors: Gholami M. R. , Talebi B. A. 
Published: December 2002

AbstractHydrogen bonding effects of protic solvents, apart from bulk properties, on the reaction rate of the cycloaddition of cylopentadiene and vinyl acetate in the presence of water and methanol in the gas phase were investigated. The results showed that methanol increases the reaction rate in the gas phase more than the water. This is attributed to the stronger hydrogen bonding effect of methanol in this phase. Ab initio and semi‐empirical calculations show that methanol stabilizes the transition state of the reaction more than water. This arises from two different origins, distribution of charge and geometry of the hydrogen bond. Copyright © 2002 John Wiley & Sons, Ltd.
RAFTing down under: Tales of missing radicals, fancy architectures, and mysterious holes
Authors: Barner‐Kowollik Christopher , Davis Thomas P. , Heuts Johan P. A. , Stenzel Martina H. , Vana Philipp , Whittaker Michael 
Published: December 2002

AbstractThis highlight describes recent developments in reversible addition–fragmentation transfer (RAFT) polymerization. Succinct coverage of the RAFT mechanism is supplemented by details of synthetic methodologies for making a wide range of architectures ranging from stars to combs, microgels, and blocks. In addition, RAFT reactions in different media such as emulsion and ionic liquids receive attention. Finally, a specific example of a novel material design is briefly introduced, whereas polymers prepared via RAFT are adopted for microporous/honeycomb membrane design. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 365–375, 2003
Kinetics of surface‐initiated atom transfer radical polymerization
Authors: Kim Jong‐Bum , Huang Wenxi , Miller Matthew D. , Baker Gregory L. , Bruening Merlin L. 
Published: December 2002

AbstractAlthough atom transfer radical polymerization (ATRP) is often a controlled/living process, the growth rate of polymer films during surface‐initiated ATRP frequently decreases with time. This article investigates the mechanism behind the termination of film growth. Studies of methyl methacrylate and methyl acrylate polymerization with a Cu/tris[2‐(dimethylamino)ethyl]amine catalyst system show a constant but slow growth rate at low catalyst concentrations and rapid growth followed by early termination at higher catalyst concentrations. For a given polymerization time, there is, therefore, an optimum intermediate catalyst concentration for achieving maximum film thickness. Simulations of polymerization that consider activation, deactivation, and termination show trends similar to those of the experimental data, and the addition of Cu(II) to polymerization solutions results in a more constant rate of film growth by decreasing the concentration of radicals on the surface. Taken together, these studies suggest that at high concentrations of radicals, termination of polymerization by radical recombination limits film growth. Interestingly, stirring of polymerization solutions decreases film thickness in some cases, presumably because chain motion facilitates radical recombination. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 386–394, 2003
Using diethylphosphites as thermally latent curing agents for epoxy compounds
Authors: Chiu Yie‐Shun , Liu Ying‐Ling , Wei Wen‐Lung , Chen Wen‐Yu 
Published: December 2002

AbstractDiethylphosphite (DEP) and its derivative exhibited thermally latent properties for epoxy curing reactions through the formation of phosphonic acid as an active species from a reaction of ethanol elimination, which was observed with 1H NMR and pyrolysis gas chromatography/mass spectrometry measurements. The thermally latent properties and curing reaction kinetics of the curing reaction of DEPs with diglycidyl ether of bisphenol A were studied with differential scanning calorimetry. The cured epoxy resins possessed a phosphorous element coming from the DEP derivatives, exhibiting improved flame retardancy. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 432–440, 2003
Cobalt‐catalyzed alternating and nonalternating copolymerization of carbon monoxide with aziridine
Authors: Zhao Jiquan , Ding Errun , Allgeier Alan M. , Jia Li 
Published: December 2002

AbstractCatalysts CH3COCo(CO)3PPh3 (1) and HCo(CO)3PPh3 (2) catalyze the copolymerization of aziridine and carbon monoxide. Catalyst 2 can be conveniently generated in
situ via reaction of Na+Co(CO)4, N,N‐dimethylanilinium chloride, and PPh3. The copolymerization alternates at high catalyst loadings to produce poly(β‐alanine). The end groups of the poly(β‐alanine) product are characterized by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry and by comparison of the 1H NMR spectra of the polymer and a stepwise synthesized model compound. At low catalyst loadings, the polymer product contains both the β‐alanine units and amine units because of nonalternating enchainment of the comonomers. The characterization of the amine units is again supported by comparison of the 1H NMR spectra of the polymers and the stepwise synthesized model compounds. The molecular weights of the polymers are determined by gel permeation chromatography. The thermal stability of the polymers is probed by differential scanning calorimetry and thermogravimetric analysis. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 376–385, 2003
Hydrophilic and hydrophobic copolymer systems based on acrylic derivatives of pyrrolidone and pyrrolidine
Authors: González Nieves , Elvira Carlos , San Román Julio 
Published: December 2002

AbstractThis article deals with the synthesis of hydrophilic methacrylic monomers derived from ethyl pyrrolidone [2‐ethyl‐(2‐pyrrolidone) methacrylate (EPM)] and ethyl pyrrolidine [2‐ethyl‐(2‐pyrrolidine) methacrylate (EPyM)] and their respective homopolymers. For the determination of their reactivity in radical copolymerization reactions, both monomers were copolymerized with methyl methacrylate (MMA), the reactivity ratios being calculated by the application of linear and nonlinear mathematical methods. EPM and MMA had ratios of rEPM = 1.11 and rMMA = 0.76, and this indicated that EPM with MMA had a higher reactivity in radical copolymerization processes than vinyl pyrrolidone (VP; rVP = 0.005 and rMMA = 4.7). EPyM and MMA had reactivity ratios of rEPyM = 1.31 and rMMA = 0.92, and this implied, as for the EPM–MMA copolymers, a tendency to form random or Bernoullian copolymers. The glass‐transition temperatures of the prepared copolymers were determined by differential scanning calorimetry (DSC) and were found to adjust to the Fox equation. Total‐conversion copolymers were prepared, and their behavior in aqueous media was found to be dependent on the copolymer composition. The swelling kinetics of the copolymers followed water transport mechanism case II, which is the most desirable kinetic behavior for a swelling controlled‐release material. Finally, the different states of water in the hydrogels—nonfreezing water, freezing bound water, and unbound freezing water—were determined by DSC and found to be dependent on the hydrophilic and hydrophobic units of the copolymers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 395–407, 2003
Syntheses and properties of novel fluorinated polyamides based on a bis(ether‐carboxylic acid) or a bis(ether amine) extended from bis(4‐hydroxyphenyl)phenyl‐2,2,2‐trifluoroethane
Authors: Hsiao Sheng‐Huei , Chen Wei‐Tsun 
Published: December 2002

AbstractTwo series of novel fluorinated aromatic polyamides were prepared from 1,1‐bis[4‐(4‐carboxyphenoxy)phenyl]‐1‐phenyl‐2,2,2‐trifluoroethane with various aromatic diamines or from 1,1‐bis[4‐(4‐aminophenoxy)phenyl]‐1‐phenyl‐2,2,2‐trifluoroethane with various aromatic dicarboxylic acids with the phosphorylation polyamidation technique. These polyamides had inherent viscosities ranging from 0.51 to 1.54 dL/g that corresponded to weight‐average and number‐average molecular weights (by gel permeation chromatography) of 36,200–80,000 and 17,200–64,300, respectively. All polymers were highly soluble in aprotic polar solvents, such as N‐methyl‐2‐pyrrolidone and N,N‐dimethylacetamide, and some could even be dissolved in less‐polar solvents like tetrahydrofuran. The flexible and tough films cast from the polymer solutions possessed tensile strengths of 76–94 MPa and initial moduli of 1.70–2.22 GPa. Glass‐transition temperatures (Tg's) and softening temperatures of these polyamides were observed in the range of 185–268 °C by differential scanning calorimetry or thermomechanical analysis. Decomposition temperatures (Td's) for 10% weight loss all occurred above 500 °C in both nitrogen and air atmospheres. Almost all the fluorinated polyamides displayed relatively higher Tg and Td values than the corresponding nonfluorinated analogues. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 420–431, 2003
Composition distribution of ethylene or propylene–norbornene copolymers obtained with zirconocene catalysts
Authors: Naga Naofumi , Imanishi Yukio 
Published: December 2002

AbstractCopolymerization of ethylene or propylene and norbornene (NB) was carried out with stereospecific zirconocene catalysts rac‐ethylenebis(indenyl)zirconium dichloride, rac‐dimethylsilylenebis(indenyl)zirconium dichloride (2), rac‐dimethylsilylenebis(2‐methylindenyl)zirconium dichloride, and diphenylmethylene(cyclopentadienyl)(9‐fluorenyl)zirconium dichloride combined with cocatalysts at 40 °C. Temperature‐rising elution fractionation of the copolymers was carried out with cross‐fractionation chromatography with o‐dichlorobenzene as a solvent, and a broad distribution of the copolymer composition was detected. The fraction eluted at lower temperature contained higher NB. The effect of the polymerization time was examined in the ethylene–NB copolymerization with catalyst 2, and the higher‐temperature elution fraction increased with increasing polymerization time. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 441–448, 2003
Performance of the Cr[CH(SiMe3)2]3/SiO2 catalyst for ethylene polymerization compared with the performance of the Phillips catalyst
Authors: Ikeda Haruhiko , Monoi Takashi , Sasaki Yasuaki 
Published: December 2002

AbstractThe catalysis of a silica‐supported chromium system {Cr[CH(SiMe3)2]3/SiO2} was compared with a silica‐supported chromium oxide catalyst, the Phillips catalyst (CrO3/SiO2). This catalyst was prepared by the calcining of the typical silica support used for the Phillips catalyst at 600 °C and by the support of tris[bis(trimethylsilyl)methyl]chromium(III) {Cr[CH(SiMe3)2]3} on the silica. In the slurry‐phase polymerization, this catalyst conducted the polymerization of ethylene at a high activity without organoaluminum compounds as cocatalysts or scavengers. The activity per Cr was about 6–7 times higher than that of the Phillips catalyst. Upon the introduction of hydrogen to the system, the molecular weight of polyethylene did not change with the Phillips catalyst, but it decreased with the Cr[CH(SiMe3)2]3/SiO2 catalyst. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 413–419, 2003
Novel route to poly(p‐phenylene vinylene) polymers
Authors: Wu Xufeng , Shi Gaoquan , Qu Liangti , Zhang Jiaxin , Chen Feng'en 
Published: December 2002

AbstractPoly(p‐phenylene vinylene) (PPV), poly(2,5‐dioctyl‐p‐phenylene vinylene) (PDOPPV), and poly[2‐methoxy‐5‐(2′‐ethylhexyloxy)‐p‐phenylene vinylene] (MEHPPV) were synthesized by a liquid–solid two‐phase reaction. The liquid phase was tetrahydrofuran containing 1,4‐bis(bromomethyl)benzene, 1,4‐bis(chloromethyl)‐2,5‐dioctylbenzene, or 1,4‐bis(chloromethyl)‐2‐methoxyl‐5‐(2′‐ethylhexyloxy)benzene as the monomer and a certain amount of tetrabutylammonium bromide as a phase‐transfer catalyst. The solid phase consisted of potassium hydroxide particles with diameters smaller than 2 mm. The experimental results demonstrated that the reaction conversions of PPV and PDOPPV were fairly high (∼65%), but the conversion of MEHPPV was only 45%. Moreover, gelation was found in the polymerization processes. As a result, PPV was insoluble and PDOPPV and MEHPPV were partially soluble in the usual organic solvents, such as tetrahydrofuran and chloroform. Soluble PDOPPV and MEHPPV were obtained with chloromethylbenzene or bromomethylbenzene as a retardant regent. The molar mass of soluble PDOPPV was measured to be 2 × 104 g mol−1, and that of MEHPPV was 6 × 104 g mol−1. A thin, compact film of MEHPPV was formed via spin coating, and it emitted a yellow light. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 449–455, 2003