[3+2] Cycloaddition Reaction for the Stereoselective Synthesis of a New Spirooxindole Compound Grafted Imidazo[2,1-b]thiazole Scaffold: Crystal Structure and Computational Study

A new spirooxindole hybrid engrafted imidazo[2,1-b]thiazole core structure was designed and achieved via [3+2] cycloaddition reaction approach. One multi-component reaction between the ethylene derivative based imidazo[2,1-b]thiazole scaffold with 6-Cl-isatin and the secondary amine under heat conditions afforded the desired compound in a stereoselective manner. The relative absolute configuration was assigned based on single-crystal X-ray diffraction analysis. Hirshfeld calculations for 4 revealed the importance of the H…H (36.8%), H…C (22.9%), Cl…H (10.4%) and S…H (6.6%), as well as the O…H (4.7%), N…H (5.3%), Cl…C (1.6%), Cl…O (1.0%) and N…O (0.5%) contacts in the crystal stability. DFT calculations showed excellent straight-line correlations (R2 = 0.9776–0.9962) between the calculated and experimental geometric parameters. The compound has polar nature (3.1664 Debye). TD-DFT and GIAO calculations were used to assign and correlate the experimental UV-Vis and NMR spectra, respectively.

Straightforward Regio- and Diastereoselective Synthesis, Molecular Structure, Intermolecular Interactions and Mechanistic Study of Spirooxindole-Engrafted Rhodanine Analogs

Straightforward regio- and diastereoselective synthesis of bi-spirooxindole-engrafted rhodanine analogs 5a–d were achieved by one-pot multicomponent [3 + 2] cycloaddition (32CA) reaction of stabilized azomethine ylide (AYs 3a–d) generated in situ by condensation of L-thioproline and 6-chloro-isatin with (E)-2-(5-(4-chlorobenzylidene)-2,4-dioxothiazolidin-3-yl)-N-(2-morpholinoethyl)acetamide. The bi-spirooxindole-engrafted rhodanine analogs were constructed with excellent diastereo- and regioselectivity along with high chemical yield. X-ray crystallographic investigations for hybrid 5a revealed the presence of four contiguous stereocenters related to C11, C12, C19 and C22 of the spiro structure. Hirshfeld calculations indicated the presence of many short intermolecular contacts such as Cl...C, S...S, S...H, O...H, N...H, H...C, C...C and H...H interactions. These contacts played a very important role in the crystal stability. The polar nature of the 32CA reaction was studied by analysis of the conceptual DFT reactivity indices. Theoretical study of this 32CA reaction indicated that it takes place through a non-concerted two-stage one-step mechanism associated with the nucleophilic attack of AY 3a to the electrophilic ethylene derivative.

Synthesis, X-ray Structure, Conformational Analysis, and DFT Studies of a Giant s-Triazine bis-Schiff Base

The current work involves the synthesis of 2,2′-(6-(piperidin-1-yl)-1,3,5-triazine-2,4-diyl)bis(hydrazin-2-yl-1-ylidene))bis(methanylylidene))diphenol 4, characterization, and the DFT studies of the reported compound. The crystal unit cell parameters of 4 are a = 8.1139(2) Å, b = 11.2637(2) Å, c = 45.7836(8) Å. The unit cell volume is 4184.28(15) Å3 and Z = 4. It crystallized in the orthorhombic crystal system and Pbca space group. The O…H, N…H, C…H, H…H and C…C intermolecular contacts which affect the crystal stability were quantitatively analyzed using Hirshfeld calculations. Their percentages were calculated to be 9.8, 15.8, 23.7, 46.4, and 1.6% from the whole contacts occurred in the crystal, respectively. Conformational analysis was performed using DFT calculations for 17 suggested conformers and the most stable conformer was found to be the one which is stabilized by two intramolecular O-H…N hydrogen bonding interactions. This conclusion was further revealed by natural bond orbital calculations.

Synthesis, Single Crystal X-ray, Hirshfeld and DFT Studies of 1,8-Dichloro-9,10-dihydro-9,10-ethanoanthracene-11-carboxylic Acid

In this paper, synthesis, single-crystal X-ray structure, Hirshfeld and DFT studies of 1,8-dichloro-9,10-dihydro-9,10-ethanoanthracene-11-carboxylic acid are discussed. Different intermolecular contacts affecting the crystal stability are studied using Hirshfeld calculations. The H…Cl and O…H contacts are the most significant, showing corresponding interaction distances of 2.731 Å (Cl2…H10) and 1.681Å (H1…O1), 2.328 Å (O1…H13), 2.510 Å (O1…H12) based on Hirshfeld calculations. DFT calculations are carried out to study the electronic behavior, as well as the 1H- and 13C-NMR spectra of the synthesized compound. The computed NMR chemical shifts show excellent correlation with the experimental data (R2 = 0.9884–0.9705).

Synthesis of C2-Symmetrical Bis-(β-Enamino-Pyran-2,4-dione) Derivative Linked via 1,6-Hexylene Spacer: X-ray Crystal Structures, Hishfeld Studies and DFT Calculations of Mono- and Bis-(Pyran-2,4-diones) Derivatives

The synthesis of C2-symmetrical bis(β-enamino-pyran-2,4-dione) derivative 3 connected via 1,6-hexylene linker was reported for the first time. X-ray structures and Hirshfeld studies of the new bis- β-enamino-pyran-2,4-dione derivative 3 along with two structurally related pyran-2,4-dione derivatives 2a,b were discussed. A comparative analysis of the different intermolecular contacts affecting the crystal stability was presented. Generally, the H…H, O…H, and H…C interactions are common in all compounds and are considered the most abundant contacts. In addition, DFT calculations were used to compute the electronic properties as well as the 1H and 13C NMR spectra of the studied systems. All compounds (except 3) are polar where 2a (3.540 Debye) has a higher dipole moment than 2b (2.110 Debye). The NMR chemical shifts were calculated and excellent correlations between the calculated and experimental data were obtained (R2 = 0.93–0.94).

Crystal structure and Hirshfeld surface analysis of trans-2,5-dimethylpiperazine-1,4-diium tetrachloridocobaltate(II)

In the title molecular salt, (C6H16N2)[CoCl4], the complete dication is generated by crystallographic inversion symmetry and the piperazine ring adopts a chair conformation with the pendant methyl groups in equatorial orientations. The complete dianion is generated by crystallographic twofold symmetry. In the crystal, the (C6H16N2)2+ and [CoCl4]2− ions are linked by N—H...Cl and C—H...Cl hydrogen bonds, thereby forming a two-dimensional supramolecular network. The Hirshfeld surface analysis and fingerprint plots reveal that the largest contributions to the crystal stability come from H...Cl/Cl...H (68.4%) and H...H (27.4%) contacts.

Study of the effect of alcoholic fermentation on the formation of crystal stability of base wines

Изменение химического состава сусла и мезги в ходе спиртового брожения приводит к нарушению равновесия, отражающегося на значениях интегральных показателей. Цель - изучение превращений компонентов сусла и мезги в ходе спиртового брожения с точки зрения кристаллической стабильности вин. Динамику показателей исследовали в условиях сбраживания мезги и сусла из винограда сорта Каберне-Совиньон. Определяли содержания сахаров, этилового спирта, титруемых и органических кислот (лимонной, яблочной, винной), ионов калия, интегральные показатели (рН, электропроводность, буферная емкость). Склонность к кристаллообразованию определяли по температуре насыщения битартратом калия. Содержание молекулярной и диссоциированных форм яблочной и винной кислот рассчитывали в зависимости от значений рН. Установлен двухфазный характер процесса брожения сусла и мезги. На I фазе сбраживания сахаров происходит повышение содержания титруемых кислот, обусловленное диссоциацией органических кислот по I ступени как следствие обогащения среды ионами водорода. Массовая концентрация винной и яблочной кислот, катиона калия при сбраживании сусла снижается более значительно, чем при брожении мезги, что сопровождается уменьшением значения температуры насыщения среды битартратом калия. II фаза брожения характеризуется меньшими изменениями физико-химических показателей, чем I: уменьшилась скорость сбраживания и накопления этанола, снижается содержание титруемых кислот, в том числе органических, а также катиона калия. Значения некоторых компонентов изменяются независимо от фазы брожения: величина рН повышается; электропроводности, катиона калия - снижается. Температура насыщения битартратом калия бродящих сред (мезги и сусла) проявляет тенденцию к снижению, что позволяет сделать вывод о стабилизирующем характере процесса брожения. Changes in the chemical composition of the must and pomace in the process of alcoholic fermentation lead to an imbalance, reflected in the values ??of integral indicators. The aim is to study the transformations of components of the must and pomace in the process of alcoholic fermentation from the point of view of the crystal stability of wines. The dynamics of indicators was investigated in conditions of fermentation of the pomace and must made of 'Cabernet-Sauvignon' grape variety. The contents of sugars, ethyl alcohol, titratable and organic acids (citric, malic and tartaric), potassium ions, integral indicators (pH, electrical conductivity, buffer capacity) were determined. The tendency to crystal formation was determined by the temperature of saturation with potassium bitartrate. The content of molecular and dissociated forms of malic and tartaric acids was calculated depending on the pH values. The two-phase character of the must and pomace fermentation process was established. On the 1st phase of sugar fermentation an increase in the content of titratable acids results due to the dissociation of organic acids along the 1st stage on the back of the enrichment of the medium with hydrogen ions. Mass concentration of tartaric and malic acids and potassium cation during the must fermentation decreases more significantly than during the pomace fermentation, accompanied by a decrease in the temperature of saturation of the medium with potassium bitartrate. The 2nd phase of fermentation is characterized by less change in physicochemical parameters than the 1st: the rate of fermentation and accumulation of ethanol has decreased as well as the content of titratable, including organic, acids and the potassium cation. Ranges ??of some components change regardless the phase of fermentation: the pH value rises; values of electrical conductivity and potassium cation - decrease. Saturation temperature of fermenting media (pomace and must) with potassium bitartrate tends to decrease, allowing to make a conclusion about the stabilizing character of fermentation process.

Study on novel structure of Mn complex, C24H18CrMnN4O5

The novel Mn complex C24H18CrMnN4O5 was investigated by hydrothermal and its crystal structure was characterized using X-ray diffraction technology. The Mn atom is six coordinated by four N atom from two 1, 10-phenanthroline and two O atoms from CrO4-. The hydrogen bonding O-H...O had central effect for crystal stability.