Synthesis,Electrical, Electronic and Charge Transport Properties of Poly(aniline‐co‐p‐toluidine)

Copolymers of aniline with p‐toluidine were synthesized for different molar ratios of the respective monomers in acid medium. The electrical conductivity, charge transport and spectral characteristics upon incorporation of p‐toluidine units into the polyaniline backbone were investigated. The electrical conductivity of the copolymers showed frequency dependence which became more prominent with an increase in the number of p‐toluidine units in the polyaniline backbone. A direct relationship between the frequency dependence and electron localization was observed in the copolymers. Electronic spectra showed blue shifts in the π→π*and benzenoid→quinoid transitions revealing a decrease in the extent of conjugation in the copolymers. The protonated forms of the copolymers were soluble in DMSO giving polaron band around 400 nm. The decrease in electrical conductivity was attributed to the greater electron localizations as revealed from the broader ESR signals. Temperature dependence of electrical conductivity showed that charge transport was mainly through variable range hopping though a mixed conduction behavior was observed at higher temperature range.     

Synthesis and properties of amphoteric copolymer of 5‐vinyltetrazole and vinylbenzyl phosphonic acid

Amphoteric polymers have been studied for various applications such as separation of low molecular weight organic molecules from inorganic salt mixtures, selective ion transport, drug delivery through membranes of biological interest, separation of ionic drugs and proteins, and separation of alcohol and water. Typical amphoteric polymers consist of weak base and weak acid groups. In present study, the copolymerization of 5‐vinyltetrazole (VT) and diisopropyl‐p‐vinylbenzyl phosphate (DIPVBP) via free radical polymerization is studied. The reactivity ratio of VT and DIPVBP, which is calculated from Kelen‐Tudos plot, is 0.251 and 0.345, respectively. The amphoteric copolymer of VT and diisopropyl‐p‐vinylbenzyl phosphonic acid (poly(VT‐co‐VBPA)) is obtained from hydrolysis of the copolymer of VT and DIPVBP (poly(VT‐co‐DIPVBP)). Poly(VT‐co‐VBPA) is thermally stable under 190 °C. The anhydrous proton conductivity of amphoteric poly(VT‐co‐VBPA) can reach 1.54 × 10^‐4 S cm^?1 at 170 °C with an activation energy of 114.7 kJ mol^?1. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3486–3493     

Novel Carbon–Carbon Bond Formation between N‐Methyl‐3‐phenyl‐3‐hydroxypropylamine and Cresols Catalyzed by p‐Toluenesulphonic Acid

The p‐toluenesulphonic acid–catalyzed reaction between appropriate cresols and N‐methyl‐3‐phenyl‐3‐hydroxypropylamine in refluxing toluene resulted in the formation of o‐substituted phenol derivatives by an aromatic nucleophilic substitution reaction.     

Experimental and theoretical electronic absorption spectra of 2,4‐diphenyl‐1,5‐benzothiazepine and its derivatives: Solvatochromic effect and time dependent density functional theory approach

Electronic spectra of 2,4‐diphenyl‐1,5‐benzothiazepine and some of its derivatives in 1,2‐dichloromethane and ethanol are investigated experimentally and theoretically using the time dependent density functional theory (TD‐DFT) method at the B3LYP/6‐311G** level of the theory. The origin of the spectrum of the parent compound is found to be an additive one. The observed ultra violet (UV) spectra in both solvents show two bands S1 in the range between 312–334 nm and S2 in the range between 248–272 nm. The solvent effect is investigated experimentally and theoretically and a blue shift is observed, which is explained in terms of a hydrogen bond model between the solvent and the most negative site of the solute (N atom). This theoretical model is robust in reproducing the experimental blue shift and calculating the hydrogen bond energy and hydrogen bond length. The extent of delocalization and charge transfer processes of the studied compounds is estimated and discussed in terms of natural bond orbital (NBO) analysis and second order perturbation interactions (E²) between donors and acceptors. The effect of substituents of the studied compounds in both solvents shows a noticeable red shift attributed to hyperconjugation effects of the π electron systems of the different moieties.     

Chiral recognition in aqueous solutions. Preferential configurations of α-aminoacids bearing substituted alkyl chains at 25°C

Calorimetric measurements were carried out at 25°C on binary and ternary aqueous solutions containing L and D forms fo the following -aminoacids: tryptophan, cysteine, methionine, phenylalanine, histidine, threonine, and citrulline, which contain both hydrophilic and hydrophobic domains. Differences were found between the values of the homochiral and heterochiral pairwise enthalpic interaction coefficients for tryptophan, cysteine, and methionine. To the contrary, chiral recognition was not detected for phenylalanine, histidine, citrulline, and threonine. The data were interpreted in terms of a preferential configuration model. Chiral recognition is detected only when the interactions of the side chains in the homo- and heterochiral configurations are different. Chiral recognition disappears when a competition exists between zwitterion-zwitterion interactions and side chain-side chain interactions. In some cases, such as for citrulline, compensation effects can occur due to thermal contributions from different domains which mask chiral recognition.     

Absence of p,π-conjugation in the Cl2C=CHOMe molecule from data ofab initio calculations

ab initio Calculation of the Cl₂C=CHOMe molecule has been carried out with geometrical optimization in the split valence basis set in the RHF/6-31G^*//RHF/6-31G^* approximation. An analysis of the populations of the p-orbitals of the Cl atoms implies the absence of p,-conjugation between the unshared electron pairs of these atoms and the -bond. The asymmetry parameters of the electric field gradient at the³⁵Cl nuclei, calculated from the 3p-orbital populations of the Cl atoms, practically coincide with the experimental values.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2369–2372, December, 1995.The authors are grateful to G. S. Beloglazov for assistance in accomplishingab initio calculations.     

The influence of cyclodextrin complexation on proton transfer in piperidinomethyl-2-naphthol

Summary Piperidinomethyl-2-naphthol forms inclusion complexes with -cyclodextrin with an equilibrium constant of 265M ^–1 in aqueous solution. The proton transfer equilibrium between the neutral and the zwitterionic form is strongly influenced by the association.

---

Der Einfluß der Komplexierung mit -Cyclodextrin auf das Protontransfer-Gleichgewicht in Piperidino-2-naphthol (Kurze Mitt.)

Zusammenfassung Piperidinomethyl-2-naphthol bildet Einschlußkomplexe mit -Cyclodextrin mit einer Gleichgewichtskonstante von 265M ^–1. Das Protontransfer-Gleichgewicht zwischen neutraler Form und zwitterionischer Struktur wird durch diese Assoziation stark beeinflußt.

     

Synthesis and ozonization of (+)-4α-(1-trimethylsilyloxyethen-1-yl)-2-carene

(+)-4-(1-Trimethylsilyloxyethen-1-yl)-2-carene was synthesized, and the products of its ozonization were identified.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1984–1987, October, 1995.     

Application of solvent extraction and synchronous spectrofluorimetry to the determination of the formation constant for a 1:1 complex of carbazole withβ-cyclodextrin in water-dimethyl sulfoxide medium

Extraction of carbazole in heptane was performed at 25±1°C with an aqueous dimethyl sulfoxide (DMSO) medium containing -cyclodextrin (CD) at consecutive concentrations in the range of 0–10 mM. The fluorescence intensity of carbazole remaining in the heptane phase was measured by synchronous scanning fluorimetry. The apparent formation constant (K _f) for a 1:1 carbazole: CD inclusion complex in water-DMSO medium was determined by using a linear plot of the distribution ratio calculated from the fluorescence intensities vs. the -CD concentration. The values thus obtained ranged from 477 M^–1 in a 10% v/v DMSO medium to 12.1 M^–1 in a 60% v/v medium. Good linear relationships were observed between logK _f and the DMSO concentration ([DMSO]), and also between logK _f and the logarithm of the distribution coefficient (K _d) for carbazole. The formation constant in 100% water was estimated to be approximately 1.0×10³ M^–1 on the basis of the logK _f vs. [DMSO] and the logK _f vs. logK _d correlations.     

Charge-transfer complexes of indenophanes with π-acceptors

The charge-transfer (CT) spectra of the -complexes formed by a number of -acceptors with several indenophanes as well as indene as a model compound have been measured in methylene chloride at 20 °C. Association constants and transition energies of these complexes as well as ionization potentials of the -donors have been determined. The data obtained indicate the existence of transannular electronic interactions in the indenophane nucleus. Furthermore, the pseudo-para- andmeta[2.2]indenophane isomers (3 and4) show a large difference in their -base strength. A good linear relationship has been observed between the association constants and _max of the long wavelength CT bands for the -complexes of these -donors with both tetracyanoethylene (TCNE) and 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ). All CT complexes studied have a 1:1 stoichiometry.

---

Charge-transfer-Komplexe aus Indenophanen und -Akzeptoren

Zusammenfassung Die Charge-transfer-Spektren (CT-Spektren) von -Komplexen aus Indenophanen bzw. der Modellverbindung Inden und verschiedenen -Akzeptoren wurden in Methylenchlorid bei 20 °C bestimmt. Die Assoziationskonstanten und Übergangsenergien dieser Komplexe sowie die Ionisationspotentiale der -Donatoren wurden ermittelt. Die Daten sprechen für das Vorliegen transannularer elektronischer Wechselwirkungen im Indenophan-System. Die isomeren pseudo-para- und -meta[2.2]indenophane3 und4 unterscheiden sich in ihrer -Basizität deutlich. Es besteht eine gute lineare Korrelation zwischen den Assoziationskonstanten und _max der langwelligen CT-Banden der verschiedenen -Donatoren mit Tetracyanoethylen (TCNE) und 2,3-Dichlor-5,6-dicyano-p-benzochinon (DDQ). Alle untersuchten CT-Komplexe besitzen 1:1-Stöchiometrie.