N. G. Gileva

Voltammetric determination of bisoprolol on a glassy carbon electrode modified by poly(arylene phthalide)

New voltammetric sensors based on glassy carbon electrodes (GCEs) modified by poly(arylene phthalide) are studied. The electrochemical behavior of bisoprolol on GCEs modified by poly(arylene phthalide) is investigated. The effects of potential scan rate, time of accumulation on the electrode, pH of supporting electrolyte, and concentration on the current of bisoprolol electrooxidation are estimated. A procedure is developed for the voltammetric determination of bisoprolol on glassy carbon electrodes modified by poly(arylene phthalide). The dependence of the analytical signal on the concentration of bisoprolol is linear in the range 10–6–10–5 M with the limit of detection (3.4–9.8) × 10–8 M.

Formation of color centers and paramagnetic species upon reduction of poly(diphenylene phthalide) with metallic lithium in DMF

Reduction of poly(diphenylene phthalide) (PDP) with metallic lithium in DMF at room temperature was studied by electronic and ESR spectroscopies. The main feature of the process is the presence of a long induction period (about 50 to 80 min) which is probably caused by the formation of small lithium particles and by adsorption of the polymer on the metal. At least four types of nonparamagnetic color centers characterized by overlapping absorption bands at 570, 660, 750, and 810 nm were detected in the reduced solution. The amounts of all types of the color centers in the solution show a complex dynamic behavior. Reduction of the polymer in the bulk of the solution is due to lithium colloid particles which give rise to a narrow asymmetric ESR singlet (g = 2.0023, ΔH = 0.03 mT, A/B ≈ 1.1–1.8) and absorb light in the region λ ∼300–400 nm. Paramagnetic species with quartet ESR signal with a splitting of 0.1 mT and g = 2.0045 observed in the solutions being reduced at a polymer concentration of 0.2 mol L−1 were attributed to radical anions of terminal anthraquinone groups (TAGs). The electron affinities of some molecules simulating the phthalide-containing unit of the polymer backbone, TAG, and a defect anthrone group were calculated in the B3LYP/6-311+G(d,p) approximation. For diphenylphthalide, the vertical electron affinity EAvert = 0.21 eV, the adiabatic electron affinity EAad = 0.66 eV, the effective electron affinity EAeff (with allowance for cleavage of C-O bond in the phthalide ring) = 1.23 eV. For anthrone group, one has EAad ∼1.2 eV and for anthraquinone group, EAad ∼2 eV. The electron affinities of the model compounds were also calculated with inclusion of the energy of solvation in two solvents (DMF and DMSO) and the energy of polarization in the PDP film. The electronic spectra of some compounds chosen as models for the expected products of reduction (anions and dianions) of the main phthalide-containing fragments in the polymer, TAGs, and defect anthrone groups were also calculated by the TD DFT B3LYP/6-311G(d,p) method. The presence of three types of chemical electron traps and the possibility of manifestation of strong absorption bands of these anions and dianions in the spectral region 500–900 nm precludes unambiguous selection and assignment of complex experimental electronic spectra observed in the course of PDP reduction. The possible role of TAGs in the electronic and photophysical processes in PDP is discussed.

Relative reactivity of monomers for polyarylenephthalides

One of the approaches to the estimation of the relative reactivity of monomers in copolycondensation is based on the determination of the content of monomer residues in a polymer product [1‐5]. In the present work, we showed that the sequence of incorporation of monomer residues into the growing chain of copolyarylenephthalides can be determined from the color of sulfuric acid solutions of a polymer sampled in the course of synthesis. It was demonstrated that the reactivity of the monomers correlates not only with the wavelength of the main absorption band of carbocations in homo- and heterodyads of intermediate copolymer samples but also with the spectral characteristics of sulfuric acid solutions of the homopolymers whose units constitute these dyads, as well as with the spectral characteristics of the ionized form of the phthalide-containing monomers. To determine the relative reactivity of aromatic (heteroaromatic) hydrocarbons, interbipolycondensation of two of the three comonomers I – III (in different combinations) with each of acid dichlorides IV – VI (intermonomer) was carried out.

Synthesis, microstructure, and properties of block copolyarylenephthalides

Two-step copolycondensation of 3-chloro-3-(4-phenoxyphenyl)phthalide and 3-chloro-3-(4-phenylthiophenyl) phthalide was studied. The influence exerted by the sequence of loading the comonomers on the order of incorporation of the monomer residues into the polymer chain and on the microstructure of the resulting copolyarylenephthalides was examined.

4′,4″-bis(2-carboxybenzoyl)diphenyl sulfone pseudodichloride as a new monomer for polyarylenephthalides

A procedure was developed for oxidation of 4′,4″-bis(2-carboxybenzoyl)diphenyl sulfide with per acids (peracetic and trifluoroperacetic). The 4′,4″-bis(2-carboxybenzoyl)diphenyl sulfone obtained was converted into pseudodichloride, and three new polyarylenephthalides with regular alternation of the electron-acceptor (diphenyl sulfone) and electron-donor (diphenyl oxide, diphenyl sulfide, terphenyl) fragments were synthesized on its basis. The synthesized monomers can be used in the synthesis of new polyarylenephthalides exhibiting the electronic switching effect.

Chromatography of conjugated polymeric carbocations

The separation of a number of homo- and copolyarylenephthalides, which were converted into a colored ionized form, by adsorption chromatography using elution with 96% sulfuric acid was studied. A correlation between the color (degree of conjugation) and the adsorption ability of chromophore groups, which were formed upon the dissolution of the test compounds in H2SO4, was found: in the separation of a mixture of two polyarylenephthalides of the same type, a polymer whose chromophore group absorbs in the short-wave-length region of the spectrum was eluted first and the polyarylenephthalide with a deeper color was eluted next. The procedure developed allowed us to analyze the polymers in microgram amounts.

Conjugation and Carbonization in the Polyarylene Phthalide Series: A New Correlation

Polyarylene phthalides (PAPs) can be considered as polyconjugated polymers in which short conjugated aromatic (heteroaromatic) fragments (‐Ar‐) alternate with phthalide groups in the backbone or as polymers with the polyconjugated backbone cleaved at the sites of phthalide group attachment

The EPR and Electronic Spectroscopy Study of Polyarylene — Sulfophthalides and Polydiphenylenephthalide Reduction by Alkali Metals

The development of organic high-spin polyradicals is of current interest in basic research as well as in materials science [1,2]. The structure of polyarylenesulfophthalides 1–3 and polydiphenylenephthalide 4, film-forming polymers containing labile cycles in the main chains, looks very promising for chemical or physical generation of stable polyradicals of triarylmethyl type (PRTAMT). The kaown chemical properties of phthalide

Nonmonotonic Variation of the Molecular-Weight Characteristics of Poly(terphenylene phthalide) during Thermooxidative Aging

Study of the M w / M n parameter can help, in principle, to solve an important problem, namely, to distinguish between intermolecular and intramolecular chain propagation in the oxidation of a polymer [1]. If the oxidative destruction of polymer chains is the predominant process, long macromolecules are the first to be cleaved and the polymer polydispersity decreases during aging. Conversely, if cross-linking predominates during aging, M w increases and the M w / M n ratio also increases. In the former case, the M w and M n values approach each other (i.e., the MWD narrows), whereas in the latter case, M w and M n disperse and the MWD is broadened (depending on the polymer chemical structure and thermooxidative destruction conditions, the MWD can become both narrower and broader [2‐4]). This is true, first of all, for the structural transformations of polymers at relatively low degrees of conversion when heat-treated samples contain no gel fraction. For high conversions (high content of the gel), the relationship between the destruction mechanism and the pattern of M w / M n variation is not unambiguous. Thus, it was found that the kinetic curves for the variation of M w / M n and M w and the number of branching points in macromolecules for poly(terphenylene phthalide) (PTP) aging in air pass through a maximum. The MWD first widens and shifts toward higher MWs; then, it starts to narrow and shifts in the opposite direction. It was shown that the nonmonotonic pattern of variation of the molecular-weight characteristics of poly(terphenylene phthalide) is due to gelation, which mainly involves the highest molecular-weight and branched portion of the polymer sol fraction, rather than to the predominance of intermolecular cross-linking at initial stages of aging and the destruction of macromolecules at high degrees of conversion. The M w and M w / M n values of the polymer were determined by GPC, and the molecular weight of the branches ( M b ) was found from the dependence of the