Within the framework of the developing field of supramolecular dynamic stereochemistry, the ability of a steviol derivative to form two stereochemically different types of homochiral dimers in crystals, namely non-symmetrical and pseudo-symmetrical, has been studied. The first type of dimer is formed by molecules of two different supramolecular diastereomers and the second type is formed by two identical ones. The formation of two different supramolecular diastereomeric forms based on the steviol molecule occurs at the stage of formation of hydrogen bonds involving stereochemically identical or different LPs of the hydroxyl oxygen atom. The analysis of the electron density Laplacian function, performed on the optimized geometry of dimers of both types, made it possible to carry out an evidence-based correlation, as well as to visualize the participation of one or another LP in a specific intradimeric hydrogen bond. Controlled conditions for obtaining phases containing dimers of a particular configuration as building blocks and the transition conditions between them were revealed.

Dynamic life of charge-transfer cocrystals.

Two crystalline modifications of ethyl-(Z)-2-(2-chlorobenzylidene)-5-(4-chlorophenyl)-7-methyl-3-oxo-2,3-dihydro-5H-thiazolo[3,2-a]pyrimidine-6-carboxylate were obtained. The triclinic form was obtained as a solvate, the orthorhombic form as an individual kryptoracemic form. Both forms were studied by X-ray diffraction analysis using quantum-chemical calculations. Heterochiral stacking dimers were found in triclinic crystals, while infinite stacks were formed in orthorhombic crystals through a set of secondary interactions: C–H···π and C–H···O. It was found that the formation of the kryptoracemic form is due to the conformational mobility of the ethyl fragment. Pure crystalline phases were obtained, confirmed by powder diffractometry. The DSC method was used to establish differences in the thermodynamic stability of crystalline forms.

Для соединений рядов хиральных ариловых эфиров глицерина с заместителем в ароматическом кольце, Alk–C6H4–OCH2CH(OH)CH2(OH) [Alk = орто-Me (1) и мета-Me (2), а также орто-Et (3), орто-н-Pr (4) и орто-изо-Pr (5)], на основании данных об их растворимости в циклогексане и термохимических параметров плавления были вычислены изменения стандартных свободных энергий растворения и плавления. Показано, что эти параметры могут быть успешно использованы для сопоставления энергетических характеристик кристаллических структур. Это в свою очередь позволило количественно оценить эффекты хиральной дискриминации в кристаллах соединений 1-5 и анализировать тенденции ее изменении при систематическом варьировании молекулярной структуры.

Получены и охарактеризованы три полиморфные модификации N4-этил-N1-(дифенилфосфорил)ацетил-тиосемикарбазида, которые представляют собой примеры упаковочного полиморфизма. Полиморфы характеризуются одинаковой конформацией молекул, которая стабилизируется внутримолекулярной водородной связью N-H…O типа, и морфологией первичных одномерных кристаллоформирующих мотивов. Установлено, что основное различие для одного из полиморфов обусловлено изменением типа акцептора водородного связывания и взаимного расположения молекул в 1D-мотиве. Для двух других полиморфов при идентичности самого 1D-мотива, различие заключается во взаимном расположении 2D-слоев, образующихся за счет взаимодействий более слабого порядка. Несмотря на то, что параллельная укладка двумерных слоев для полиморфа с двумя независимыми молекулами оказывается несколько выгоднее антипараллельной укладки, реализующейся в кристалле полиморфа с Z´=1, результаты ДСК свидетельствуют, что последний является термодинамической формой при нормальных условиях. Показано, что для полиморфов наблюдается подобие структурной организации кристаллических решеток, которое заключается в локализации в кристаллах областей, содержащих гидрофильные и гидрофобные фрагменты молекул.

For a series of chiral para-alkylphenyl glycerol ethers-para-Alk-C6H4-OCH2CH(OH)CH2(OH) [Alk = Me (1), Et (2), n-Pr (3), n-Bu (4), iso-Pr (5), tert-Bu (6)]-we used information on their solubility in cyclohexane and thermochemical melting parameters to calculate the standard free energies of dissolution, , and melting, Delta G0f. Our observations showed consistent patterns in these parameters within the homologous series. This analysis allowed us to compare the energy characteristics of the crystal structures, thus enabling the quantification of enantiophobic and enantiophilic effects. Furthermore, it facilitated the examination of trends in chiral discrimination as the molecular constitution changed sequentially. We identified distinct trends for enantiopure substances and corresponding racemic compounds within the series studied. In particular, the difference in crystal packing energies among the series members following these trends favours racemic molecular compounds by approximately 2.5 kJ mol-1. However, for (R)-3 and (R)-4, the realised crystal structures are more energetically favoured than expected, thus deviating from the established correlations. This anomaly allows homochiral crystal structure 3 to bridge the energy gap and crystallise from the racemic mixture as a thermodynamically more favourable conglomerate of enantiomeric crystals. In contrast, for racemic compound rac-5, the energy of its molecular packing is lower than expected from the correlations but insufficient to make conglomerate 5 thermodynamically more favourable. At the same time, the formation of racemic compound rac-6 was abnormally preferable in terms of energy. In addition, we presented the X-ray diffraction data for the homo- and heterochiral crystals of 5, thereby complementing the structural information available for the "chiral pool" class of glycerol derivatives. Solubility- and melting-based approaches to estimate the inner-crystal chiral discrimination are present.

Three polymorphs of N4-ethyl-N1-(diphenylphosphoryl)acetyl-thiosemicarbazide, which exemplify packing polymorphism, are obtained and characterized. Polymorphs have the same molecular conformation stabilized by the intramolecular N–H⋯O hydrogen bond and the morphology of primary 1D crystal-forming motifs. The main difference of one of the polymorphs is known to be due to a change in the type of the hydrogen bonding acceptor and the arrangement of molecules in the 1D motif. In the other two polymorphs with the identical 1D motif, the difference consists in the arrangement of 2D layers formed by weaker interactions. Despite that the parallel packing of 2D layers for the polymorph with two independent molecules appears to be somewhat more favorable than the antiparallel packing occurring in the polymorph crystal with Z′ = 1, the DSC results indicate that the latter is the thermodynamic form under normal conditions. It is shown that the polymorphs are characterized by a similar structural organization of crystal lattices which consists in the localization of regions containing hydrophilic and hydrophobic molecular fragments in the crystals.

Changes in the standard free energies of dissolution Δ G_soln^S^293 and melting Δ G_f^293 are calculated for the compounds of a series of chiral aryl glycerol ethers with a substituent in the aromatic ring Alk–C6H4–OCH2CH(OH)CH2(OH) (Alk = ortho-Me (1) and meta-Me (2), ortho-Et (3), ortho-n-Pr (4), and ortho-iso-Pr (5)) based on their solubility in cyclohexane and thermochemical melting parameters. These parameters are shown to be successfully used to compare energy characteristics of the crystal structures. This allows us to quantify chiral discrimination effects in the crystals of compounds 1–5 and analyze the trends of its change when the molecular structure is systematically varied.

Tertiary diethylpyridylphosphine was synthesized by the reaction of pyridylphosphine with bromoethane in a suberbasic medium. The reaction of phosphine with the copper(I) iodide led to the formation of a copper(I) coordination polymer, which, according to the X-ray diffraction data, has an intermediate structure with a copper-halide core between the octahedral and stairstep geometries of the Cu4I4 clusters. The obtained coordination polymer exhibits a green emission in the solid state, which is caused by the 3(M+X)LCT transitions. The heating up of the copper(I) coordination polymer to 138.5 °C results in its monomerization and the formation of a new solid-state phase. The new phase exhibits a red emission, with the emission band maximum at 725 nm. According to the experimental data and quantum chemical computations, it was concluded that depolymerization probably leads to a complex that is formed with the octahedral structure of the copper-halide core. The resulting solid-state phase can be backward-converted to the polymer phase via recrystallization from the acetone or DMF. Therefore, the obtained coordination polymer can be considered a sensor or detector for the overheating of processes that should be maintained at temperatures below 138 °C (e.g., engines, boiling liquids, solar heat systems, etc.).

We managed to detect and measure chiral discrimination in the crystalline phase of the continuous solid solution of enantiomers of para-propoxyphenyl glycerol ether. To this end, we performed a series of experiments on the comparison of compositions of saturated solutions above the equilibrium solid phases with those of the solid phases themselves. For the solid solutions it is shown that the chiral discrimination can be quantitatively characterized through the energy difference of the molecules of two enantiomers in the inner crystal environment. For the system under study in the composition range x > 0.8, this value is –1.2 kJ/mol. The results presented demonstrate that according to thermochemical data, the almost ideal behavior of the solid solutions of enantiomers, according to the thermochemical data, can actually conceal significant effects of the chiral discrimination in the solid phase.

N1-(diphenylphosphoryl)acetyl-thiosemicarbazide in individual form composes a double corrugated layer in the crystal due to a branched system of N–H…O/S hydrogen bonds. A similar supramolecular organization is observed in methanol and ethanol crystal solvates containing solvent molecules inside 1D channels. It is shown that the dimensionality of the cavities and the layered type of the supramolecular organization of the molecules of the main substance in crystals provide the possibility for the solvent molecules to of freely leave the crystal, while the supramolecular structure and crystallinity of the studied phase is preserved. It is established that single crystals of the individual compound can be obtained only as a result of a solid-phase “single crystal–single crystal” transition from the solvate with methanol rather than by direct crystallization, since any solvent yields the corresponding crystal solvate. It is established for a number of cases that solid-phase “polycrystal–polycrystal” transitions are reversible, can be initiated by the solvent vapors, and are accompanied by the formation of the corresponding crystalline solvate.

N1-(дифенилфосфорил)ацетил-тиосемикарбазид в индивидуальном виде формирует в кристалле двойной гофрированнный слой за счет разветвлённой системы N-H…O/S водородных связей. Аналогичная супрамолекулярная организация наблюдается и для кристаллосольватов с метанолом и этанолом, при этом молекулы растворителя находятся в одномерных каналах. Показано, что мерность полостей и слоевой тип супрамолекулярной организации молекул основного вещества в кристаллах открывает возможность беспрепятственного удаления молекул растворителя из кристалла с сохранением супрамолекулярной структуры и кристалличности исследуемой фазы. Установлено, что монокристаллы индивидуального соединения могут быть получены только в результате твердофазного перехода типа “монокристалл-монокристалл” из сольвата с метанолом, но не могут быть получены путем прямой кристаллизации, так как любой растворитель будет давать соответствующий кристаллосольват. Для ряда случаев выявлено, что твердофазные переходы “поликристалл-поликристалл” имеют обратимый характер и могут индуцироваться парами растворителя с образованием соответствующего кристаллосольвата.

На примере неограниченного твердого раствора энантиомеров пара-пропоксифенилового эфира глицерина нам удалось обнаружить и измерить хиральную дискриминацию в твердой фазе. Для этого мы провели серию экспериментов по сопоставлению состава насыщенных растворов над твердой фазой с составом самой твердой фазы. Обнаружено, что во внутрикристаллическом окружении молекула ощущает энантиофилию, которая в области составов x > 0.8 может быть примерно оценена в –1.2 кДж моль–1. Представленные результаты демонстрируют, что за внешне близким к идеальному поведению твердых растворов энантиомеров по термохимическим данным могут скрываться существенные эффекты хиральной дискриминации в твердой фазе.

The crystal structures of 3-chloro-5-hydroxy-1-(4-methylbenzyl)-4-[4-phenyl-1H-1,2,3-triazole-1-yl]-1,5-dihydro-2Н-pyrrol-2-one rac-1 and 1-benzyl-3-chloro-5-hydroxy-4-[4-phenyl-1H-1,2,3-triazole-1-yl]-1,5-dihydro-2Н-pyrrol-2-one rac-2 are studied. The reproducibility of a same-type homochiral chain in both chiral and racemic crystals is found. Molecular conformations, secondary interactions additionally cross-linking the chain, and π…π contacts between the cyclic molecular moieties are analyzed.

We confirm our previously formulated rule about the possibility of a spontaneous resolution of enantiomers of a series of 5-hydroxy-3-pyrrolin-2-one thioderivatives. Crystal packings of three racemic compounds are compared. A supramolecular associate of the same type (a hydrogen-bonded dimer) is found, which is differently packed in the 3D structure of the crystals.

A rare phase behavior of rac-1-benzyl-3-bromo-4-[(4-chlorophenyl)sulfanyl]-5-hydroxy-1,5-dihydro-2H-pyrrol-2-one, which consists of the formation of two normal monoclinic and hexagonal conglomerates and a monoclinic racemic compound, has been discovered by thermochemical and X-ray diffraction methods. Its monoclinic racemic compound is reproducibly formed as a result of the suspension by stirring the solid phase in hydrocarbons at room temperature, while routine crystallization from a solution leads to the formation of a mixture of the two conglomerates. Thermochemical data suggest that the monoclinic conglomerate is metastable within the entire temperature range, the monoclinic racemic crystal is stable under normal conditions (20 degrees C) up to 110 degrees C, and the hexagonal conglomerate is stable at elevated temperatures above 110 degrees C. The essential structural difference between the homo-and heterochiral crystals lies in the optimal mutual orientation of the donor and acceptor groups of the H-bonds for the former case and the unfavorable mutual orientation for the latter one.

Изучены кристаллические структуры 5-гидрокси-1-(4-метилбензил)-4-[4-фенил-1H-1,2,3-триазол-1-ил]-3-хлор-1,5-дигидро-2Н-пиррол-2-она rac-1 и 1-бензил-5-гидрокси-4-[4-фенил-1H-1,2,3-триазол-1-ил]-3-хлор-1,5-дигидро-2Н-пиррол-2-она rac-2. Обнаружена воспроизводимость однотипной гомохиральной цепочки как в хиральных, так и в рацемическом кристаллах. Проанализированы конформации молекул, вторичные взаимодействия, дополнительно сшивающие цепочку, π…π контакты между циклическими фрагментами молекул.

Подтверждено сформулированное нами ранее правило возможности спонтанного разделения энантиомеров серии тиопроизводных 5-гидрокси-3-пирролин-2-она. Проведен сравнительный анализ кристаллической упаковки трёх рацемических соединений. Обнаружен однотипный супрамолекулярный ассоциат – водородносвязанный димер, по-разному упаковывающийся в трёхмерную структуру в кристаллах.