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A major societal issue of disposal and environmental pollution is raised by the enormous and fast-growing production of single-use polyethylene terephthalate (PET) bottles, especially in developing countries. To contribute to the problem solution, an original route to recycle PET in the form of value-added environmentally friendly thermoplastic composites with banana fibres (Musa acuminata) has been developed at the laboratory scale. Banana fibres are a so far undervalued by-product of banana crops with great potential as polymer reinforcement. The melt-processing constraints of commercial PET, including used bottles, being incompatible with the thermal stability limits use of natural fibres; PET has been modified with bio-sourced reactants to produce co-polymers with moderate processing temperatures below 200°C. First, commercial PET were partially glycolyzed with 1.3-propanediol to produce co-oligomers of about 20 repeating units, which were next chain extended with succinic anhydride and post-treated in a very unusual “soft solid state” process at temperatures in the vicinity of the melting point to generate co-polymers with excellent ductility. The molar mass build-up reaction is dominated by esterification of the chain ends and benefits from the addition of succinic anhydride to rebalance the acid-to-hydroxyl end-group ratio. Infra-red spectroscopy and intrinsic viscosity were extensively used to quantify the concentration of chain ends and the average molar mass of the co-polymers at all stages of the process. The best co-polymers are crystallisable, though at slow kinetics, with a Tg of 48°C and a melting point strongly dependent upon thermal history. The composites show high stiffness (4.8 GPa at 20% fibres), consistent with the excellent dispersion of the fibres and a very high interfacial cohesion. The strong adhesion can be tentatively explained by covalent bonding involving unreacted succinic anhydride in excess during solid stating. A first approach to

Background. Development of sensor systems based on synthetic mimics of biological molecules will provide new effective express-methods for detection of small organic molecules, including pharmaceuticals, for modern analytical biotechnology.Objective. An analytical system for highly selective and sensitive detection of sulfamethoxazole based on molecularly imprinted polymer (MIP) membranes is proposed, synthesized using the method of in situ polymerization in a combination with the method of computational modeling.Methods. Sulfamethoxazole molecules, that were selectively adsorbed by the synthetic binding sites in MIP membranes structure, were visualized due to their ability to form brown-colored complexes after reaction with potassium ferricyanide and sodium nitroprusside in alkaline media.Results. The limit for sulfamethoxazole detection comprised 2 mM, while the linear dynamic range – 2–15 mM, which allows one to detect sulfamethoxazole in pharmaceutical preparations. Stability of the developed MIP-based sensor systems was estimated as at least 6 months, which significantly increases stability of analogous devices based on natural receptors.Conclusions. Applicability of the developed sensor systems for the analysis of sulfamethoxazole in both model solutions and real samples (commercial pharmaceutical preparations) was proven. The developed systems are characterized with high selectivity, sensitivity, small size and low cost., Проблематика. Разработка сенсорных систем на основе искусственных аналогов биологических макромолекул является актуальной для современной аналитической биотехнологии, поскольку обеспечивает новые эффективные экспресс-методы детекции малых органических молекул, в том числе фармацевтических препаратов.Цель исследования. В работе предлагается аналитическая система для высокоселективного и чувствительного определения сульфаметоксазола на основе молекулярно импринтированных полимерных (МИП) мембран, синтезированных с использованием метода полимеризации in situ в комбинации с методом компьютерного моделирования.Методика реализации. Молекулы сульфаметоксазола, селективно адсорбированные синтетическими рецепторными сайтами в структуре МИП мембран, визуализировали благодаря их способности формировать окрашенные в коричневый цвет комплексы после реакции с феррицианидом калия и нитропруссидом натрия в щелочной среде.Результаты исследования. Предел обнаружения сульфаметоксазола составил 2 мМ, а линейный динамический диапазон сенсорной системы – 2–15 мМ, что дает возможность определять сульфаметоксазол в фармацевтических препаратах. Стабильность разработанных сенсорных систем на основе МИП составила по крайней мере 6 месяцев, что значительно превосходит стабильность аналогичных приборов на основе природных рецепторов.Выводы. Доказана возможность использования разработанных сенсорных систем для анализа сульфаметоксазола как в модельных, так и в реальных образцах (коммерчески доступных фармацевтических препаратах). Разработанные сенсорные системы характеризуются высокой селективностью, чувствительностью, портативностью и невысокой стоимостью., Проблематика. Розробка сенсорних систем на основі штучних аналогів біологічних макромолекул є актуальною для сучасної аналітичної біотехнології, оскільки забезпечує нові ефективні експрес-методи детекції малих органічних молекул, в тому числі фармацевтичних препаратів.Мета дослідження. У роботі пропонується аналітична система для високоселективного та чутливого визначення сульфаметоксазолу на основі молекулярно імпринтованих полімерних (МІП) мембран, синтезованих із застосуванням методу полімеризації in situ у комбінації з методом комп’ютерного моделювання.Методика реалізації. Молекули сульфаметоксазолу, селективно адсорбовані штучними рецепторними сайтами у структурі МІП мембран, візуалізували завдяки їх здатності формувати забарвлені у коричневий колір комплекси після реакції з фериціанідом калію та нітропрусидом натрію в лужному середовищі.Результати дослідження. Межа визначення сульфаметоксазолу становила 2 мМ, а лінійний динамічний діапазон роботи сенсорної системи – 2–15 мМ, що дає змогу визначати сульфаметоксазол у фармацевтичних препаратах. Стабільність розроблених сенсорних систем на основі МІП становила принаймні 6 місяців, що значно перевищує стабільність аналогічних пристроїв на основі природних рецепторів.Висновки. Доведено придатність розроблених сенсорних систем для аналізу сульфаметоксазолу як у модельних, так і в реальних зразках (комерційно доступних фармацевтичних препаратах). Розроблені сенсорні системи характеризуються високою селективністю, чутливістю, портативністю та невисокою вартістю.

Проблематика. Останнім досягненням у галузі матеріалознавства для поліпшення фізико-хімічних властивостей стало використання фізичної модифікації полімерних матеріалів. Особливу увагу дослідників привертає обробка зовнішнім постійним магнітним або електричним полем полімерних матеріалів під час тверднення.Мета дослідження. Визначити вплив властивостей різних за природою оксидів металів на динаміко-механічні характе­ристики мезокомпозитів.Методика реалізації. Методом динаміко-механічного аналізу було проведено дослідження зразків мезокомпозитів наповнених оксидами металів, які піддані твердненню при дії фізичних полів.Результати дослідження. Орієнтаційний вплив фізичних полів змінює континуум молекул, що беруть участь у реакції поліприєднання та при формуванні певної структури епоксидного полімеру, і зумовлює зростання його вільного об’єму. Набута відмінність модулів еластичності зберігається в інтервалі температур 293–340 К, а при збільшенні температури, внаслідок переходу епоксидного полімеру до високоеластичного стану, орієнтаційні впливи фізичних полів втрачаються. Зразки, сформовані під впливом фізичних полів, характеризуються значно більшими величинами модуля еластичності порівняно зі зразками, сформованими за нормальних умов. Температурні залежності модулів втрат епоксидного полімеру та композитів наповнених оксидами металів, що піддані твердненню за різних умов, збігаються.Висновки. Показано раціональність залучення кислотно-основних властивостей до спрямованої модифікації кристалічної структури, теплофізичних, діелектричних та динаміко-механічних властивостей мезокомпозитів., Background. The latest development in the field of materials to improve the physical and chemical properties is the use of physical modification of polymeric materials. Special attention attracts treatment of external constant magnetic or electric fields of polymeric materials during curing.Objective.To determine the effects of different natural properties of metal oxides on dynamic mechanical properties of mezocomposites.Methods. By dynamic mechanical analysis methodstudyof mezocomposite samples filled with oxides of metals, cured by the action of physical fieldswas conducted.Results. Orientation influence of physical fields changes continuum of molecules involved in the reaction of polyaddition and in the formation of epoxy polymer structure, and leads to the growth of its free volume. Acquiredelasticity modulus difference is stored in the temperature range of 293–340 K, and when the temperature increases, due to the transition to highly polyepoxy state, the orientation influences of physical fields are lost. Samples were formed under the influence of physical fields are characterized by much higherelasticity modulus values compared with samples formed under normal conditions. Temperature dependence modules losses of epoxy polymer and composites filled with oxides of metals cured under different conditions coincide.Conclusions. Rationality involvement of acid-base properties to crystal structure aimed modification, thermophysical, dielectric and dynamic mechanical properties of mezocomposites is shown., Проблематика. Последним достижениям в области материаловедения для улучшения физико-химических свойств стало использование физической модификации полимерных материалов. Особое внимание исследователей привлекает обработка внешним постоянным магнитным или электрическим полем полимерных материалов при отверждении.Цель исследования. Определить влияние свойств различных по природе оксидов металлов на динамико-механические характеристики мезокомпозитов.Методика реализации. Методом динамического механического анализа было проведено исследование образцов мезокомпозитов наполненных оксидами металлов, отвержденных при действии физических полей.Результаты исследования. Ориентационное влияние физических полей меняет континуум молекул, участвующих в реакции полиприсоединения и при формировании определенной структуры эпоксидного полимера, и вызывает рост его свободного объема. Приобретенное отличие модулей эластичности сохраняется в интервале температур 293–340 К, а при увеличении температуры, в результате перехода эпоксидного полимера в высокоэластичное состояние, ориентационные влияния физических полей теряются. Образцы, сформированные под влиянием физических полей, характеризуются значительно большими величинами модуля эластичности по сравнению с образцами, сформированными при нормальных условиях. Температурные зависимости модулей потерь эпоксидного полимера и композитов наполненных оксидами металлов, отвержденных при различных условиях, совпадают.Выводы. Показано рациональность привлечения кислотно-основных свойств к направленной модификации кристаллической структуры, теплофизических, диэлектрических и динамико-механических свойств мезокомпозитов.

Background. Development of sensor systems based on synthetic mimics of biological molecules will provide new effective express-methods for detection of small organic molecules, including pharmaceuticals, for modern analytical biotechnology.Objective. An analytical system for highly selective and sensitive detection of sulfamethoxazole based on molecularly imprinted polymer (MIP) membranes is proposed, synthesized using the method of in situ polymerization in a combination with the method of computational modeling.Methods. Sulfamethoxazole molecules, that were selectively adsorbed by the synthetic binding sites in MIP membranes structure, were visualized due to their ability to form brown-colored complexes after reaction with potassium ferricyanide and sodium nitroprusside in alkaline media.Results. The limit for sulfamethoxazole detection comprised 2 mM, while the linear dynamic range – 2–15 mM, which allows one to detect sulfamethoxazole in pharmaceutical preparations. Stability of the developed MIP-based sensor systems was estimated as at least 6 months, which significantly increases stability of analogous devices based on natural receptors.Conclusions. Applicability of the developed sensor systems for the analysis of sulfamethoxazole in both model solutions and real samples (commercial pharmaceutical preparations) was proven. The developed systems are characterized with high selectivity, sensitivity, small size and low cost., Проблематика. Разработка сенсорных систем на основе искусственных аналогов биологических макромолекул является актуальной для современной аналитической биотехнологии, поскольку обеспечивает новые эффективные экспресс-методы детекции малых органических молекул, в том числе фармацевтических препаратов.Цель исследования. В работе предлагается аналитическая система для высокоселективного и чувствительного определения сульфаметоксазола на основе молекулярно импринтированных полимерных (МИП) мембран, синтезированных с использованием метода полимеризации in situ в комбинации с методом компьютерного моделирования.Методика реализации. Молекулы сульфаметоксазола, селективно адсорбированные синтетическими рецепторными сайтами в структуре МИП мембран, визуализировали благодаря их способности формировать окрашенные в коричневый цвет комплексы после реакции с феррицианидом калия и нитропруссидом натрия в щелочной среде.Результаты исследования. Предел обнаружения сульфаметоксазола составил 2 мМ, а линейный динамический диапазон сенсорной системы – 2–15 мМ, что дает возможность определять сульфаметоксазол в фармацевтических препаратах. Стабильность разработанных сенсорных систем на основе МИП составила по крайней мере 6 месяцев, что значительно превосходит стабильность аналогичных приборов на основе природных рецепторов.Выводы. Доказана возможность использования разработанных сенсорных систем для анализа сульфаметоксазола как в модельных, так и в реальных образцах (коммерчески доступных фармацевтических препаратах). Разработанные сенсорные системы характеризуются высокой селективностью, чувствительностью, портативностью и невысокой стоимостью., Проблематика. Розробка сенсорних систем на основі штучних аналогів біологічних макромолекул є актуальною для сучасної аналітичної біотехнології, оскільки забезпечує нові ефективні експрес-методи детекції малих органічних молекул, в тому числі фармацевтичних препаратів.Мета дослідження. У роботі пропонується аналітична система для високоселективного та чутливого визначення сульфаметоксазолу на основі молекулярно імпринтованих полімерних (МІП) мембран, синтезованих із застосуванням методу полімеризації in situ у комбінації з методом комп’ютерного моделювання.Методика реалізації. Молекули сульфаметоксазолу, селективно адсорбовані штучними рецепторними сайтами у структурі МІП мембран, візуалізували завдяки їх здатності формувати забарвлені у коричневий колір комплекси після реакції з фериціанідом калію та нітропрусидом натрію в лужному середовищі.Результати дослідження. Межа визначення сульфаметоксазолу становила 2 мМ, а лінійний динамічний діапазон роботи сенсорної системи – 2–15 мМ, що дає змогу визначати сульфаметоксазол у фармацевтичних препаратах. Стабільність розроблених сенсорних систем на основі МІП становила принаймні 6 місяців, що значно перевищує стабільність аналогічних пристроїв на основі природних рецепторів.Висновки. Доведено придатність розроблених сенсорних систем для аналізу сульфаметоксазолу як у модельних, так і в реальних зразках (комерційно доступних фармацевтичних препаратах). Розроблені сенсорні системи характеризуються високою селективністю, чутливістю, портативністю та невисокою вартістю.

A survey of our recent work on synthetic polynucleotide analogs is given. Propionic acid and 3-methyl butyric acid derivatives substituted in the 2-position with nucleic acid bases have been used as chiral pendants for attachment to hydrophilic polyamine backbones. Hindered rotation about the amide bonds formed promotes a base-stacked structure as shown by ultraviolet hypochromic effects versus model compounds. If the pendant has been resolved, an optically active polymer results which may be studied by circular dichroism (CD). Thus, poly(ethylenimine) containing the (−)-2-(thymin-1-yl)-propionyl group as the grafted pendant showed exciton coupling of the B 2u transition of the base chromophores in the CD, as observed in polynucleotides. This implies at least a local helical order in the stacking. The biological activity of such structures is briefly discussed.

A sample of high molecular weight poly(diethyl siloxane), [Si(C2H5)2---O---]x, (PDES) was separated into a series of fractions by means of liquid-liquid precipitations. Four of the fractions were studied by osmometry and viscometry in toluene at 25[deg]C. The resulting values of the number-average molecular weight, second virial coefficient, and intrinsic viscosity indicate that the unperturbed dimensions of PDES are essentially the same as those of poly(dimethyl siloxane) (PDMS) of the same chain length. Thus, differences in intramolecular interactions between these two chains have little effect on their unperturbed dimensions. Most pertinent in this regard are interactions between the side chains, which are favourable in trans conformations in both PDES and PDMS. These favourable interactions in trans conformations would be enhanced in the case of the ethyl groups in PDES, but this effect is apparently offset by a comparable increase in favourable interactions between ethyl groups and oxygen atoms in the competing gauche conformations.

By using impedance spectroscopy and optical microscopy methods the investigation of electrical properties of systems based on polypropylene glycol was conducted. It was shown that adding exfoliated layered fillers to the system shifts percolation threshold to low concentration of nanotubes. Analysis of critical indexes of conductivity for investigated systems has shown that such low values of t (1,19—1,43) mean that the formation of conductive network because of strong interaction between laponite and single nanotubes is not a statistic percolation process and distribution of filler particles is nonuniform. Thus, incorporation of third component leads to significant change of percolation properties of filled system, because of its strong interaction with conductive particles. Moreover, insertion of third component leads to significant enhancement of distribution of nanotubes in the bulk of polymer matrix and can improve a number of properties of system filled with nanosized particles polymers., Используя метод импедансной спектроскопии и оптичес­кой микроскопии, были проведены исследования электрических свойств систем на основе полипропиленгликоля и карбонанотрубок (КНТ). Показано, что при введении в систему слоистого наполнителя, который эксфолиирует, происходит смещение порога перколяции в область более низких концентраций КНТ. Анализ критических индексов проводимости для исследуемых систем показал, что такие низкие значения t (1,19–1,43) свидетельствуют о том, что формирование электропроводной сетки, вследствие сильного притягивания между индивидуальными КНТ и лапонитом, не является статистическим перколяционным процессом, который предусматривает равномерное распределение наполнителя. Таким образом, введение третьего компонента за счет его взаимодействия с наноразмерными электропроводящими частичками приводит к существенному изменению перколяционных свойств наполненной системы, что в значительной степени отображается на электрической проводимости композитов., Використовуючи методи імпедансної спектроскопії та оптичної мікроскопії, проведено дослідження електричних властивостей систем на основі поліпропіленгліколю і карбонанотрубок (КНТ). Показано, що при введенні в систему шаруватого наповнювача, який ексфоліює, відбувається зміщення порога перколяції в область нижчих концентрацій КНТ. Аналіз критичних індексів провідності для досліджуваних систем виявив, що такі низькі значення t (1,19–1,43) свідчать про те, що формування провідної сітки, завдяки сильному притяганню між індивідуальними КНТ та лапонітом, не є статистичним перколяційним процесом, який передбачає рівномірне розподілення частинок нанонаповнювача. Таким чином, введення третього компонента за рахунок його взаємодії з нанорозмірними електропровідними частинками веде до істотної зміни перколяційних властивостей наповненої системи, що значною мірою відображається на електричній провідності композитів.

The aim of the present study was the evaluation of nitrate, nitrite, nitrosodiethylamine (NDEA) and nitrosodimethylamine (NDMA) intake by food consumption. We determined concentrations of nitrates, nitrites in 102 food samples (40 meat products, 15 fermented cheese, 25 vegetables, 22 fruits) and the concentration NDEA, NDMA in 40 meat products. Nitrates and nitrites were determined using Peter-Griess method; nitrosamines were quantified by HPLC with UV detection. We designed vegetalian, vegetarian and conventional diets of about 2500 kcal/day. Based of the values found, we calculated the intake of nitrates, nitrites and nitrosamines. The obtained values fits to WHO’s recommendations, except for vegetalian and conventional diet, in which the nitrate content was 3,46 respectively 1,64 times higher than the acceptable daily intake (157 mg NO3-/day).

This work presents an analysis of the structural, electrochemical, and optical properties of a family of triisopropylsilyl end-capped oligothienoacenes (TIPS- T n -TIPS, n =4???8) by combining cyclic voltammetry, spectroscopic techniques, and quantum-chemical calculations. TIPS- T n -TIPS compounds form stable radical cations, and dications are only obtained for the longest oligomers ( n =7 and 8). Oxidation leads to the quinoidization of the conjugated backbone, from which electrons are mainly extracted. The absorption and fluorescence spectra show partially resolved vibronic structures even at room temperature, due to the rigid molecular geometry. Two well-resolved vibronic progressions are observed at low temperatures due to the vibronic coupling, with normal modes showing wavenumbers of ???1525 and ???480???14cm ???1 . Optical absorption bands display remarkable bathochromic dispersion with the oligomer length, indicative of the extent of ?? conjugation. The optical properties of the oxidized compounds are characterized by in situ UV/Vis/NIR spectroelectrochemistry. The radical cation species show two intense absorption bands emerging at energies lower than in the neutral compounds. The formation of the dication is only detected for the heptamer and the octamer, and shows a new band at intermediate energies. Optical data are interpreted with the help of density functional theory calculations performed at the B3LYP/6-31G** level, both for the neutral and the oxidized compounds.

A detailed investigation of the optical and electrochemical properties of two pentathienoacene derivatives, 2,6-bis(trimethylsilyl)-Α-pentathienoacene ( TMS-T5-TMS ) and 2,6-bis(triisopropylsilyl)-Α-pentathienoacene ( TIPS-T5-TIPS ), as the neutral and oxidized species was performed in the temperature range of 80–300 14K. The experimental solution UV/Vis and solid-state Raman spectra were interpreted by using time-dependent DFT and DFT quantum chemical calculations at the B3LYP/6-31G** level. Bond lengths, HOMO–LUMO positions, and charge distribution were also predicted by computational methods for both the neutral and oxidized states of each thienoacene. As evidenced by ESR and spectroelectrochemical data, upon oxidation the pentathienoacene derivative with the less sterically hindering trimethylsilyl solubilizing groups, TMS-T5-TMS , undergoes Π 14dimerization to form [ TMS-T5-TMS ] 2 2+ . In contrast, TIPS-T5-TIPS , with the more bulky triisopropylsilyl solubilizing groups, was oxidized to the radical cation but dimerization was prevented due to steric interactions. These experimental observations are supported by DFT calculations, which were used to investigate [ TMS-T5-TMS ] 2 2+ and [ TIPS-T5-TIPS ] 2 2+ Π 14dimers in the solid state and in solution. The redox potentials and absorption peak locations corresponding to the radical cations and Π 14dimer of TMS-T5-TMS were identified experimentally.

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This article reports a continuation of our work on the substituent effects on the preferred helical conformations and the mutarotation of substituted poly(L -prolines). The size of the substituent has been increased from a methyl group to an ethyl group in the 5 position. The purpose is twofold: (i) according to our theoretical conformational energy calculations, an ethyl group in the 5 position can exert a greater steric effect than can a methyl group; and (ii) the rotation-isomerization of the ethyl group introduces a new intriguing fact to the problem. The cis isomer of 5-ethylproline was synthesized by catalytic hydrogenation of?????-2-ethylpyrroline-5-carboxylic acid, whereas for trans -5-ethylproline, a chemical separation method involving p -toluenesulfonyl chloride was used. The resolution of cis -5-ethylproline and the assignment of absolute configurations have been carried out by fractional crystallization and circular dichroism spectroscopic techniques, respectively. Poly(cis -5-ethyl- D -proline) was obtained from its corresponding N -carboxyanhydrides via a ring opening polymerization.

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The adenine base grafted polyacrylamides and their corresponding monomer model compounds were prepared and examined. The results suggest that the monomer model compounds exist in a preferred conformation, whereas the adenine base grafted polyacrylamides exist in a limited ordered conformation in an aqueous medium.

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Asymmetric linear and cross-linked imidazole-containing polymers were prepared from 1-[2(S)-methylbutyl]-4-vinylimidazole and 1-[2(S)-methylbutyl]-5-vinylimidazole. The esterolytic reactions of these linear and cross-linked asymmetric polymers with the enantiomeric substrates (R)- and (S)-4-(3-methylpentadecanoyl)-3-nitrobenzoic acid, (R)- and (S)-S − 3Me15 , were studied by measuring the pseudo-first order kinetics of the solvolysis of these enantiomeric substrates in the presence of these asymmetric polymers. The linear homopolymers and copolymers of 1-[2(S)-methylbutyl]-4- and 5-vinylimidazole showed hydrophobic and electrostatic effects in the solvolysis of the enantiomeric substrates with these linear asymmetric polymers. Cross-links were introduced into these asymmetric polymers to increase the rigidity and reduce the number of conformations available to the polymer. The reduced conformational mobility was expected to enhance any enantioselectivity in the solvolysis of the enantiomeric substrates with these polymers. Using these cross-linked polymers, hydrophobic interactions were observed in the solvolysis of a series of substrates with increasing alkyl chain length. Also, on changing the polarity of the solvent, a bell-shaped rate profile was observed in the solvolysis of the long chain substrate S − 3Me15 . This effect was attributed to a combination of the coiling of the cross-linked polymer chains and hydrophobic interactions with the substrate on changing solvent polarity. Even with the increased rigidity of these cross-linked polymers, no significant enantioselectivity in the solvolysis of the enantiomeric substrates was observed. So, neither the linear nor the cross-linked asymmetric polyvinylimidazoles showed enantioselectivity in the solvolysis of these enantiomeric substrates. In this case, the hydrophobic interactions and the reduced conformational mobility through crosslinking were not strong enough to bring about enantioselectivity in the solvoly

Polynucleotide analogs consisting of poly(vinylamine) as the backbone and optically active thymine and adenine derivatives as the pendants were synthesized. The pendants were prepared by the addition reaction of the nucleic acid base to ethyl crotonate followed by hydrolysis. The pendants were resolved using brucine as the resolving agent and an acetone-water mixture as the fractional crystallization solvent. The active esters of the pendants also were prepared. Poly(vinylamine) was isolated from water employing a weak acid, N -hydroxysuccinimide (HOSu), to protect the amino group of the poly(vinylamine). Model reactions for grafting were examined. Grafting reactions were carried out by reacting the active esters with the PVAm. 6HOSu complex at room temperature.

Poly(L - trans -3-ethylproline), L -PT3EP, and poly(D - trans -3-ethylproline), D -PT3EP, were prepared by ring opening polymerization of the corresponding N -carboxyanhydrides (NCA) using triethylamine as an initiator. Using circular dichroism spectroscopy, it was shown that the incorporation of an ethyl group at the 3 position of the pyrrolidine ring caused a noticeable change in the conformational behavior of the polymer in solution. The ethyl group limited to some extent rotation of the polymer chain around the C [bond] [bond]CO bond and prevented the mutarotation between the two forms found in poly- L -proline polymers.

Preparation of new model polymers of polynucleotides with poly(vinylamine-vinylalcohol) [P(Vam-Val)] backbones and different kinds of nucleic acid base derivatives as grafted pendants is described. At first, the grafting of (−) and (±)-2-(thymin-1-yl)propionic acid [(−) and (±)TPA] onto linear P(Vam-Val) at the amino group via an amide bond was carried out in a mixed solvent of ethanol-dimethylformamide by selective N-acylation of the active ester of N -hydroxy-5-norbornene-2,3-dicarboximide (HONB) or N -hydroxysuccinimide (HOSu). This procedure gave the corresponding hydroxyl polymers P[Vam(−)T-Val] and P[Vam(±)T-Val]. In addition, direct, low temperature esterification was used to graft (−), (±)TPA, and (±)-2-(uracil-1-yl)propionic acid, [(±)UPA], onto the hydroxyl polymer at the hydroxyl group via an ester bond. This process gave the corresponding copoly(Vam-Val) with different or the same kinds of nucleic acid base derivatives. P[Vam(−)-Ve(−)T], P[Vam(±)T-Ve(±)T], P[Vam(−)T-Ve(±)U], and P[Vam(±)T-Ve(±)U] are representative examples. The related monomer and segmental model compounds were also prepared by this method; 3-aminopentane, 3-pentanol, 3-amino-1-propanol, and threo-2-amino-4-pentanol were employed in the syntheses. The segment models were separated and purified using HPLC techniques.

The synthesis, separation, and optical resolution of cis - and trans -3-ethylproline are described. Two different approaches were employed: (1) The Michael addition reaction of 2-pentenal with diethyl-N-carbobenzyloxyaminomalonate gave the intermediate 3-ethyl-5-hydroxy-N-benzyloxypyrrolidine. Hydrogenolysis of this intermediate followed by acid hydrolysis gave a mixture of cis - and trans -3-ethylproline. Separation of the isomers was accomplished by selective saponification of N-(p -toluenesulfonyl)- cis - and trans -3-ethylproline methyl esters using 0.25 N methanolic sodium hydroxide. (2) The Michael condensation of diethyl acetamidomalonate with 2-pentenoic acid ethyl ether produced the intermediate 5,5-bis(ethoxycarbonyl)-4-ethylpyrrolidine. Partial saponification followed by decarboxylation afforded a mixture of cis - and trans -isomers of ethyl-3-ethylpyroglutamate. The diastereoisomers were separated using low temperature fractional crystallization. Reduction of these isomers and tosylation in situ afforded the corresponding N-(p -toluenesulfonyl)- cis - and trans -3-ethylprolinols. Chromic acid oxidation gave N-(p -toluenesulfonyl)- cis - and trans -3-ethylproline. Reaction of these tosylates with 30% hydrogen bromide in acetic acid gave cis - and trans -3-ethylproline. Both optically active isomers of D(+)-and L( - )- trans -3-ethylproline were successfully resolved using (+)-dibenzoyl- D -tartaric acid and ( - )-dibenzoyl- L -tartaric acid as resolving agents. The absolute configurations of the optically active isomers were determined by circular dichroism spectroscopy.

A comparison of the UV absorption spectra of a carbazole-substituted N -acylated linear polyethylenimine (PEI) (5, 6) with its monomer (1, 2) and dimer (3, 4) model compounds shows the presence of local conformational order of the carbazole groups in 3, 5, and 6 since these compounds exhibit hypochromism. The UV absorption spectra of carbazole-substituted N -acrylated dehydroalanine main-chain polymer (PDA) (12, 13) and monomer (10, 11) model compounds indicate that the extent of local conformational order of the carbazole groups is reduced in 12 and 13 compared to that in 5 and 6 . The UV absorption spectra of a pyrene-substituted PEI (9) and PDA (15) and those of their monomer model compounds (7, 14) indicate that the extent of local conformational order of the pyrene groups is greater in 9 than in 15 and furthermore the pyrene-substituted polymers (9, 15) show more local conformational order than analogous carbazole-substituted polymers (5, 12). The emission spectra of 5 and 12 show carbazole monomer emission, while those of 9 and 15 are dominated by pyrene excimer emission. The formation of excimer emission is more efficient in 9 than in 15 . Fluorescence lifetime measurements indicate interactions of excited carbazole groups in 5 and 13 but not in 12 . The quenching of carbazole fluorescence by dimethyl terephthalate is more efficient in 5 than that in 12, indicating more efficient transfer of electronic energy in 5 . These measurements show that the PEI main-chain polymers are conducive to interactions of the pendant groups.

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Poly(ethylene glycol methyl ether)tosylate was prepared and used to initiate the polymerization of 2-methyl-2-oxazoline. The resulting poly(ethylene glycol methyl ether)-b-poly(N -acetyl ethylenimine) was hydrolyzed and neutralized to give poly(ethylene glycol methyl ether)-b-poly(ethyl-enimine) (PEO-PEI). 2-(thymin-1-yl)propionic acid, N -Cbz-alanine, N -Cbz-proline, N -Cbz-O- t -Bu-serine. and N -FMOC-proline were grafted onto the PEO-PEI copolymer; attempts were then made to remove the Cbz and FMOC protecting groups.

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Preparations of new model polymers of polynucleotides with linear polyethylenimine (PEI) backbones and optically active nucleic acid base derivatives as pending side chains are described. (±)-2-(Thymin-1-yl)propionic acid (II) and (±)-2-(adenin-9-yl)propionic acid (IV) were synthesized. These carboxylic acid derivatives were grafted onto PEI at the imino nitrogen by the p -nitrophenyl active ester method. The enantiomeric pairs of II were optically resolved with quinine to yield (−) and (+)-2-(thymin-1-yl)propionic acid (VII and VIII). VII and VIII were grafted onto PEI through amide bond by direct coupling with diethylphosphoryl cyanide to give optically active graft polymers. The related monomer and dimer model compounds were also prepared by the same method from diethylamine and dimethylethylene diamine, respectively.

(+) (S)- and (???) (R)- trans -1,2-cyclopropanedicarboxylic acids (C3A), (+) (S)- and (???) (R)- trans -1,2-diaminocyclopropanes (C3B), (+) (S)- and (???) (R)- trans -2-phenylcyclopropylamines (??C3B), (+) (S)- and (???) (R)- trans -1,2-bis(methylamino)-cyclopropanes (C3MB), and (+) (S)- and (???) (R)- trans -(2-phenylcyclopropyl)-methylamines (??C3MB) were prepared.

The mutarotation between form I and form II of poly(cis -5-ethyl- D -proline) has been experimentally realized. A number of hydrogen-bond-forming solvents have been found effective in initiating the mutarotational process. The rate of mutarotation seems to be proportional to the acidity of the active solvent. The enthalpy of activation energy for the mutarotation is estimated from the first-order kinetics at the lower conversion by means of the Arrhenius equation to be approximately 16.7 kcal/mol. The solvent-polymer interactions are proven to be one of the important driving forces for the mutarotation. The specific site at which hydrogen bonding takes place has been determined to be the carbonyl group of the amide by infrared spectroscopic techniques. The molecular reason for the greater susceptibility of poly(cis -5-ethyl- L -proline) II to the solvent effect than poly(cis -5-ethyl- L -proline) I can be satisfactorily explained by the relatively more extended structure of form I than form II. The mechanism for the mutarotation undoubtedly involves a cis-trans isomerization of the amide bond. The conformation of the transient states during the mutarotational process is still evidently helical in nature, probably consisting of long poly(cis -5-ethylproline) I and II segments.

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The solvolytic reactions of anionic activated esters (S n − ) catalyzed by dodecane-block-poly[ethylenimine-graft-4(5)-methylimidazole] and related model compounds were investigated. Hydrolysis of 4-acetyl-3-nitrobenzoic acid (S 2 − ) as a function of pH suggested that electrostatic interactions are operative only in the higher molecular weight polymers. Apolar interactions were evident from the greater catalytic rates observed for the hydrolysis of a series of 4-acetoxy-3-nitrobenzoic acid substrates (S n − ). The largest rate enhancements were reflected by catalysts that make effective use of the electrostatic interaction and also provide an apolar binding site. Dodecane-block-poly[ethylenimine-graft-4(5)-methylimidazole], with a DP = 85, catalyzed hydrolysis of S n − (n = 2, 4, and 7), in excess substrate, exhibited saturation kinetics and followed a simple Michaelis-Menten-type mechanism. Inhibition of the catalyst in the hydrolysis of S 12 − was observed and can be rationalized by analogy to certain multisite enzymatic reactions.

A graft copolymer of L -histidine on polyethylenimine has been demonstrated to be an efficient catalyst for the hydrolysis of activated phenyl esters in aqueous systems. A lack of any significant cooperative effects between neighboring imidazoles or amines has been shown by a study of the catalytic solvolysis of p -nitrophenyl acetate at varying pH. A similar study with 4-acetoxy-3-nitrobenzoic acid has displayed a bell-shaped pH-rate profile indicative of electrostatic interactions between the catalyst and substrate. Hydrophobic interactions were also evident from an investigation of the hydrolytic rates of a series of 4-acyloxy-3-nitrobenzoic acids. In an attempt to demonstrate stereospecific catalyzed reactions, the hydrolyses of optically active esters catalyzed by the optically active copolymer were studied.

No Abstract.

4-Nitro- N -vinylphthalimide (4) was synthesized by two different procedures. Compound 4 was not polymerizable or copolymerizable by AIBN. Poly(N -vinylphthalimide) (17) was prepared and partially nitrated at 10-25°C. N, N 2 (1,2-Ethanediyl)bis(4-nitrophthalimide) (15) and N, N 2 (1,3-propanediyl)bis(4-nitrophthalimide) (16) were prepared by the condensation of the corresponding diamine with phthalic anhydride followed by nitration of the condensation products. 4-Nitrophthalic anhydride was prepared by the hydrolysis of 15 . Four styrene-substituted phthalimide monomers were synthesized. These include N -(4-vinylphenyl)phthalimide (25a), N -(4-vinylphenyl)-3-fluorophthalimide (25b), N -(4-vinylphenyl)-3-nitrophthalimide (25c), and N -(4-vinylphenyl)-4-nitrophthalimide (25d). Monomers 25a and 25b were polymerized by freeradical initiator (AIBN), whereas monomers 25c and 25d were not polymerizable or copolymerizable by AIBN due to a strong inhibitive effect exerted by the nitrophthalimide group. Monomers 25c and 25d were cationically polymerized (BF 3 ·OEt 2). Monomer 25b and styrene were copolymerized and their reactivity ratios were r 1 = 1.7 and r 2 = 0.55, respectively. The prepared polymers are useful as backbone polymers for grafting living anionic polymers.

An optically active polypeptide, poly(trans -5-ethylproline) (PT5EP) was synthesized and its solution properties were observed to investigate the conformational changes with various conditions. The trans -5-ethyl substitution on polyproline showed noticeable perturbed effects on the conformations of the polypeptide as well as mutarotation of the polypeptide in solution. Circular dichroism (CD) spectra suggested that the polypeptide existed in a poly(L -proline) form-I-type helix and mutarotated slowly to an intermediate conformation in which some of the amide bonds had rotated to a trans conformation. In trifluoroethanol (TFE) solution the polymer took more than 20 days to change from a form-I-type helix conformation, in which CD bands for D -PT5EP are at 199.5 ± 1.0 (positive), 115.5 ± 0.5 (negative), and around 238 nm (positive), to an intermediate conformation. Upon addition of trifluoroacetic acid (TFA) to a TFE solution, the polymer was transformed to form-II-type polymers. Even a greater change in conformation was observed in a solution of TFA or in LiClO 4 -TFE. The overall change of the intensity ratio R CD of positive to negative CD bands of D -PT5EP was from 0.6-0.7 to 30. Reverse mutarotation toward the original form I was observed when n -butyl alcohol, water, or THF was added to a solution containing the form II polymer. A blue shift of the UV spectra and a change in the NMR spectrum also supported the concept of this conformational change.

Polymere Reagentien bieten eine Reihe einzigartiger Vorteile. Intramolekulare Reaktionen, z. B. die Cyclisierung von Peptiden oder Dieckmann-Cyclisierungen, lassen sich erzwingen, wenn eine Polymerkette in gen??gend gro??en Abst??nden mit dem reaktiven Molek??l beladen wird. Verankert man reaktive Molek??le dagegen in kleinen Abst??nden an einem polymeren Tr??ger, treten intermolekulare Reaktionen ein, wie am Beispiel einer Ketonsynthese demonstriert wird. Neben diesen Nachbarschaftseffekten lassen sich kooperative Effekte ausnutzen, z. B. bei der Bildung eines 2: 1-Komplexes aus einem Kronen??ther und einem Alkalimetall-Ion. Am Beispiel der Hydrolyse eines Esters mit Polyvinylimidazol wird eingehend??ber hydrophobe Wechselwirkungen berichtet. Die einfache Trennung polymer-gebundener und niedermolekularer Verbindungen durch Filtration ist ein weiterer wesentlicher Vorteil.

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Optical properties and conformations, in solution, of optically active polyamides derived from (+)(S)- trans -1,2-cyclopropanedicarboxylic acid with secondary diamines such as trans -2,5-dimethylpiperazine (DMPIP), piperazine (PIP), or N, N???-dimethylethylenediamine (DMED) have been investigated and compared with the corresponding diamide model compounds. The results suggest that the rigid DMPIP and PIP polyamides may exist in ordered conformations in 2,2,2-trifluoroethanol (TFE) and tetramethylene sulfone (TMS), while reversible conformational transitions to highly extended forms may be induced by the addition of methanesulfonic acid (MSA). In MSA/TMS mixtures, a change in the optical properties, and thus possibly in the conformations, can be observed around 0.5 mole fraction of MSA. A study of CD at higher temperature indicates that the conformations of the DMPIP and PIP polymides tend to be randomized on heating in TMS and probably also in MSA. No evidence for salt effects on conformation has been observed. Possible ordered conformations have been proposed.

No Abstract.