Relations between the aromaticity and magnetic dipole transitions in the electronic spectra of hetero[8]circulenes

Magnetically induced current densities have been calculated at the second-order MOller-Plesset perturbation theory (MP2) level for seven hetero[8]circulenes and their dicationic and dianionic forms. Calculations of the magnetic dipole transition moments have also been carried out at the algebraic diagrammatic construction (ADC(2)) and the second-order approximate coupled-cluster (CC2) levels. The calculations show that the degree of aromaticity and the size of the magnetic dipole transition moment of the lowest magnetic-dipole allowed excited state are related. We show that neutral hetero[8]circulenes are weakly antiaromatic when the first excited state with a large magnetic dipole transition moment of 10-16 a.u. lies at high energies (approximate to 2.8-3.5 eV). For the dications, this transition often lies at much lower energies. Hetero[8]circulene dications with large magnetic dipole transition moments are strongly antiaromatic. The lowest excited states of the hetero[8]circulene dianions have very small magnetic dipole transition moments implying that they are aromatic.Peer reviewe

First-principles method for calculating the rate constants of internal-conversion and intersystem-crossing transitions

A method for calculating the rate constants for internal-conversion (k(IC)) and intersystem-crossing (k(ISC)) processes within the adiabatic and Franck-Condon (FC) approximations is proposed. The applicability of the method is demonstrated by calculation of k(IC) and k(ISC) for a set of organic and organometallic compounds with experimentally known spectroscopic properties. The studied molecules were pyrromethene-567 dye, psoralene, hetero[8]circulenes, free-base porphyrin, naphthalene, and larger polyacenes. We also studied fac-Alq(3) and fac-Ir(ppy)(3), which are important molecules in organic light emitting diodes (OLEDs). The excitation energies were calculated at the multi-configuration quasi-degenerate second-order perturbation theory (XMC-QDPT2) level, which is found to yield excitation energies in good agreement with experimental data. Spin-orbit coupling matrix elements, non-adiabatic coupling matrix elements, Huang-Rhys factors, and vibrational energies were calculated at the time-dependent density functional theory (TDDFT) and complete active space self-consistent field (CASSCF) levels. The computed fluorescence quantum yields for the pyrromethene-567 dye, psoralene, hetero[8]circulenes, fac-Alq(3) and fac-Ir(ppy)(3) agree well with experimental data, whereas for the free-base porphyrin, naphthalene, and the polyacenes, the obtained quantum yields significantly differ from the experimental values, because the FC and adiabatic approximations are not accurate for these molecules.Peer reviewe

Dianthracenylazatrioxa[8]circulene: synthesis, characterization and application in OLEDs

A soluble, green-blue fluorescent, pi-extended azatrioxa[8]circulene was synthesized by oxidative condensation of a 3,6-dihydroxycarbazole and 1,4-anthraquinone by using benzofuran scaffolding. This is the first circulene to incorporate anthracene within its carbon framework. Solvent-dependent fluorescence and bright green electroluminescence accompanied by excimer emission are the key optical properties of this material. The presence of sliding pi-stacked columns in the single crystal of dianthracenylazatrioxa[8]circulene is found to cause a very high electron-hopping rate, thus making this material a promising n-type organic semiconductor with an electron mobility predicted to be around 2.26 cm(2) V-1 s(-1). The best organic light-emitting diode (OLED) device based on the dianthracenylazatrioxa[8]circulene fluorescent emitter has a brightness of around 16 000 Cd m(-2) and an external quantum efficiency of 3.3 %. Quantum dot-based OLEDs were fabricated by using dianthracenylazatrioxa[8]circulene as a host matrix material.Peer reviewe

The Study of Ethanol Extracts Composition of Organic (Kachkulnya Lake) and Organomineral (Barchin Lake) Sapropels from Novosibirsk Region

Изучена экстракция сапропелей Новосибирской области органического (оз. Качкульня) и органоминерального (оз. Барчин) типов этанолом при варьировании температуры процесса. Повышение температуры от 50 до 200 °C приводит к увеличению выхода экстрактов в 19,0 и 13,7 раз для сапропелей органического и органоминерального типов соответственно. Методами ИК-спектроскопии и хромато-масс-спектрометрии установлен состав полученных экстрактов. Продукты из сапропеля органического типа содержат 68,1 % этиловых эфиров, преимущественно жирных кислот с числом атомов углерода в молекуле от 18 до 29. В экстрактах сапропелей органоминерального типа относительное содержание этиловых эфиров составляет 43,6 %, в состав которых кроме этиловых эфиров жирных кислот входят в значительных количествах этиловые эфиры окси- и гидроксикислот. Отличительной особенностью экстрактов сапропеля органоминерального типа является наличие в нем углеводов и соединений, включающих в свой состав фурановый циклThe extraction of sapropels of organic type (Kachkulnya Lake) and organo-mineral type (Barchin Lake) from Novosibirsk region by ethanol at a variation of process temperature was studied. It was shown that the rising of the temperature from 50 °C to 200 °C results in an increase the yields of extracts by 19,0 and 13,7 times for sapropels organic and organo-mineral -types respectively The composition of obtained extracts was established by IR and GC – MC methods. Products from sapropel organic type contained 68,1 % ethyl esters, mainly of fatty acids with carbon atoms in the molecule are from 18 to 29 numbers. It was established that relative content of ethyl esters in extract of organo-mineral type sapropel was 43,6 %, they have a significant amounts of ethyl esters of hydroxy – and oxyacids. A distinctive feature of the ethanol extract from organo-mineral type sapropel is the presence of carbohydrates and compounds containing a furan rin

New records of Holocene polar bear and walrus (Carnivora) in the Russian Arctic

This article discusses recent finds of Holocene polar bear and walrus from the northern regions of Russia. The ulna of a polar bear was found on Vaygach Island and radiocarbon dated to 1,971 +/- 25 BP (OxA-23631). This calibrates to 430-540 AD, taking into account the marine reservoir effect. The size of the bone is similar to that of a recent Ursus maritimus. The locality of the fossil bone is within the modern species range, which developed about two millennia ago. In 2014 a walrus tusk was found on the coast of New Siberia Island and is radiocarbon dated to 5,065 +/- 35 BP (GrA-62452). This calibrates to 3,510-3,370 BC, taking into account the marine reservoir effect. Its size and morphology are identical to that of an adult male of the subspecies Odobenus rosmarus laptevi. This subspecies populates the eastern parts of the Kara Sea, the entire Laptev Sea and the western parts of the East Siberian Sea. This new discovery could mean that populations of O. rosmarus laptevi inhabited the waters near the New Siberian Islands during the Middle Holocene, and that the present-day coastline of the Siberian Arctic Islands was already formed at that time

Продуктивность лактирующих коров при использовании в рационах сенажа из вико-овсяно-гороховой смеси с внесением нового биологического консерванта

The effect of a new biological preservative representing a mix of lyophilized Lactobacillus plantarum VKPM V-4173, Lactococcus lactis subsp. lactis VKPM V-2092 and Propionibacterium acidipropionici VKPMV-5723 strains (40 : 40 : 20) on the quality of haylage prepared from a mix of vetch, oats, and pea has been studied. The total bacteria content in the preservative was 1·1011 CFU/g. Five different variants of conservation of alfalfa haylage prepared at the budding stage were evaluated under laboratory conditions. The variants included a self-conserved control and the preservative at two different dosages (3 and 6 g/ton) with and without the addition of cellulolytic enzymes. The best results were observed in the case of both the enzyme-free and the enzyme-containing preservative at the dosage equal to 6 g/ton. These variants provided the maximum protein content in the haylage (94.3% and 94.5% of the initial content, respectively) and a high content of lactic acid (62.9% and 65.4% of the total acid content, respectively) and also good organoleptic characteristics. The determined optimum biopreservative dosage was tested under industrial conditions using 750 tons of vetch-oats-pea haylage. The use of the biopreservative provided a high-quality haylage of high nutritive value. Industrial evaluation of the effect on the productivity of milk cattle (n = 15) of the addition of the biopreservative to the haylage showed that the maximum average daily yield of milk with basic fat content (3.4%) was obtained from cows of the experimental group whose ration included haylage prepared with the use of the studied preservative. This yield came to32.7 kg , which exceeded the yield for the control group (fed on self-conserved haylage) by 7.0%. Three months feeding of cows with the haylage prepared with the use of the new preservative brought a significant saving of money (4,862 rubles per a head at the prices of 2015–2016). Исследовано влияние нового биологического консерванта, представляющего собой смесь лиофильно высушенных бактерий: Lactobacillus plantarum ВКПМ В-4173, Lactococcus lactis subsp. lactis ВКПМ В-2092 и Propionibacterium acidipropionici ВКПМ В-5723 (в соотношении 40 : 40 : 20) на качество сенажа из вико-овсяно-гороховой смеси. Общее содержание бактерий в консерванте составляло 1·1011 КОЕ/г. В лабораторном опыте оценены четыре варианта закладки сенажа из люцерны, приготовленного в фазе бутонизации, с нормами внесения консерванта 3 и 6 г/т в присутствии и в отсутствие ферментов. В качестве контроля использовали самоконсервированный сенаж. По результатам эксперимента наилучшие результаты обеспечивало внесение биоконсерванта в количестве 6 г/т как совместно с ферментом, так и без него. В этих вариантах отмечена высокая сохранность протеина (94,5% и 94,3% от содержания в исходной массе) и высокое содержание молочной кислоты (65,4% и 62,9% от общего содержания всех кислот), а также хорошие органолептические показатели. Указанная оптимальная норма внесения биоконсерванта протестирована в производственных испытаниях при закладке 750 тонн сенажа из вико-овсяно-гороховой смеси. Применение биоконсерванта позволило получить сенаж высокого качества, имеющий высокую энергетическую и питательную ценность. Проведены производственные испытания с оценкой эффекта скармливания сенажа, заготовленного путем самоконсервирования (контроль) и с внесением исследуемого биоконсерванта (опыт), на молочную продуктивность новотельных коров черно-пестрой породы (n = 15), качество молока и затраты кормов на единицу продукции. Среднесуточный удой молока базисной жирности (3,4%) коров опытной группы в период раздоя составил 32,7 кг, что на 7% выше по сравнению с контрольными животными, получавшими самоконсервированный сенаж. Скармливание молочным коровам в период раздоя сенажа из вико-овсяно-гороховой смеси с внесением нового биологического консерванта обеспечило экономию в размере 4 862 рубля на голову в ценах 2015–2016 года.Исследовано влияние нового биологического консерванта, представляющего собой смесь лиофильно высушенных бактерий: Lactobacillus plantarum ВКПМ В-4173, Lactococcus lactis subsp. lactis ВКПМ В-2092 и Propionibacterium acidipropionici ВКПМ В-5723 (в соотношении 40 : 40 : 20) на качество сенажа из вико-овсяно-гороховой смеси. Общее содержание бактерий в консерванте составляло 1·1011 КОЕ/г. В лабораторном опыте оценены четыре варианта закладки сенажа из люцерны, приготовленного в фазе бутонизации, с нормами внесения консерванта 3 и 6 г/т в присутствии и в отсутствие ферментов. В качестве контроля использовали самоконсервированный сенаж. По результатам эксперимента наилучшие результаты обеспечивало внесение биоконсерванта в количестве 6 г/т как совместно с ферментом, так и без него. В этих вариантах отмечена высокая сохранность протеина (94,5% и 94,3% от содержания в исходной массе) и высокое содержание молочной кислоты (65,4% и 62,9% от общего содержания всех кислот), а также хорошие органолептические показатели. Указанная оптимальная норма внесения биоконсерванта протестирована в производственных испытаниях при закладке 750 тонн сенажа из вико-овсяно-гороховой смеси. Применение биоконсерванта позволило получить сенаж высокого качества, имеющий высокую энергетическую и питательную ценность. Проведены производственные испытания с оценкой эффекта скармливания сенажа, заготовленного путем самоконсервирования (контроль) и с внесением исследуемого биоконсерванта (опыт), на молочную продуктивность новотельных коров черно-пестрой породы (n = 15), качество молока и затраты кормов на единицу продукции. Среднесуточный удой молока базисной жирности (3,4%) коров опытной группы в период раздоя составил 32,7 кг, что на 7% выше по сравнению с контрольными животными, получавшими самоконсервированный сенаж. Скармливание молочным коровам в период раздоя сенажа из вико-овсяно-гороховой смеси с внесением нового биологического консерванта обеспечило экономию в размере 4 862 рубля на голову в ценах 2015–2016 года

Aromaticity and photophysics of tetrasila- and tetragerma-annelated tetrathienylenes as new representatives of the hetero[8]circulene family

The electronic structure, absorption and emission spectra, aromaticity and photophysical behavior of the recently synthesized tetrasilatetrathia[8]circulene and tetragermatetrathia[8]circulene compounds have been studied computationally. Both compounds demonstrate a specific bifacial aromaticity, which is unusual for hetero[8]circulenes; the inner eight-membered core sustains an expected strong paratropic magnetically-induced ring current, while the outer perimeter contains saturated Si(Et)2 and Ge(Et)2 moieties which break the conjugation between the thiophene rings. The overall magnetically-induced ring current for both studied circulenes is close to zero because of the strong local diatropic currents in each thiophene ring that compensate the paratropic counterpart. The electronic absorption and emission spectra of tetrasilatetrathia[8]circulene and tetragermatetrathia[8]circulene demonstrate a clear visible vibronic progression. The 0–0 band is the most active one in the absorption spectra, while in the fluorescence spectra the 0–1 band composed of several normal vibrations is more intense compared with the 0–0 band in excellent agreement with experiment. Accounting for spin–orbit coupling effects, an analysis of the photophysical constants for the two compounds demonstrates: (1) a clear manifestation of the internal heavy atom effect on the inter-system crossing efficiency; (2) one to two order domination of non-radiative rates over the fluorescence rate; and (3) that the S1–S0 internal conversion is extremely slow and can not compete with the fluorescence, while the S1–Tn inter-system crossing is a main deactivation channel of the S1 excited state. These results provide new insight into the electronic structure and photophysics of tetrasilatetrathia[8]circulene and tetragermatetrathia[8]circulene as novel standalone representatives of hetero[8]circulenes – tetraannelated derivatives of tetrathienylene.Peer reviewe

Statistical mechanics of voting

Decision procedures aggregating the preferences of multiple agents can produce cycles and hence outcomes which have been described heuristically as `chaotic'. We make this description precise by constructing an explicit dynamical system from the agents' preferences and a voting rule. The dynamics form a one dimensional statistical mechanics model; this suggests the use of the topological entropy to quantify the complexity of the system. We formulate natural political/social questions about the expected complexity of a voting rule and degree of cohesion/diversity among agents in terms of random matrix models---ensembles of statistical mechanics models---and compute quantitative answers in some representative cases.Comment: 9 pages, plain TeX, 2 PostScript figures included with epsf.tex (ignore the under/overfull \vbox error messages