Tytuł Data publikacji Autor
Most of the biologically active substances are chiral and enantiomers can interact differently with living organisms. Hence, enantiomer resolution and asymmetric synthesis are of great importance for the pharmaceutical, chemical, and food industries. In 2013 we have reported our X-ray diffraction studies on racemic 1-benzoyl-3-(1-phenylethyl)thiourea (1) and its S-enantiomer (2). In next two years both R- and S-enantiomers of this ligand were successfully used in synthesis of chiral ruthenium(II) catalysts for stereoselective reduction of ketones. On the other hand, chiral resolution can be done chromatographically or, sometimes, by crystallization. According to Wallach’s rule, racemates form denser, more stable crystals than enantiomers. However, the validity of the rule is often broken and many exceptions have been reported so far. High pressure favours high density solids and therefore can be applied for enantiomeric resolution of the chiral compounds defying Wallach’s rule. It has been estimated by Jacques, Collet, and Wilen that the racemates less dense than the enantiomers should be spontaneously separated below 1 GPa. Here we report our high pressure study of 1 (monoclinic crystals, space group C2/c) and 2 (orthorhombic crystals, space group P212121) up to at least 3.45 GPa. A series of high-pressure single-crystal diffraction experiments have been performed at High Pressure ID09A Beamline at ESRF (Grenoble, France) using parallel monochromatic X-ray beam (E = 30 keV, λ = 0.413 Å) focused to 30 × 30 μm on the sample loaded into membrane Diamond Anvil Cell and topped by silicon oil. Similarities and differences in 1 and 2, as well as potential possibility of resolution under high-pressure were discussed within the poster.
2017
Andrzej Okuniewski,
Damian Paliwoda,
Jarosław Chojnacki,
Michael Hanfland,
Barbara Becker
Linearly arranged metal atoms embedded in a discrete molecules have been fascinating scientists across various disciplines for decades; this is attributed to their potential use in microelectronic devices on a submicroscopic scale. The development of coordination compounds based on linearly arranged metal atoms that potentially serve as conducting wires in molecular microelectronics has made tremendous progress over the recent years. Auᴵ···Auᴵ aurophilic interactions, which generally originate from relativistic and correlation effects, are comparably strong as hydrogen bonds. Because of the decrease of relativistic effects with a decreasing nuclear charge, Agᴵ···Agᴵ argentophilic bonding is less pronounced and Cuᴵ···Cuᴵ cuprophilic interactions are considered to be very weak or not significant at all. Except for rare examples of the unsupported Cuᴵ···Cuᴵ contacts, multinuclear Cuᴵ complexes exhibiting cuprophilic interactions usually require a suitable ligand framework to incorporate the cuprous ions in close proximity to each other. In the poster, we will describe the synthesis and characterization of rare, linearly arranged complexes with copper atom chains, derived from CuCl and benzoylthioureas.
2017
Damian Rosiak,
Andrzej Okuniewski,
Jarosław Chojnacki
3-Substituted 1-acylthioureas are readily prepared by the reaction of acyl chlorides, thiocyanates, and primary or secondary amines. In this manner we have synthesized 1-benzoyl-3-(2-naphthyl)-3-phenylthiourea (I). The product is obtained in the form of crystals that tend to be of poor quality for diffraction experiments. However, attempts to synthesize complexes of I with CuX (X = Cl, Br, I, SCN) were made. It turned out that crystals isolated from the reaction liquors were built out of (Z)-N-(3-phenylnaphtho[2,1-d]thiazol-2(3H)-ylidene)benzamide molecules (II). Obviously thiourea derivative undergoes the following oxidative cyclization. Two polymorphs of II were isolated and structurally characterized. One of them crystalizes in the triclinic space group P-1 (IIa), while the second one in the monoclinic space group P2₁/c (IIb). The most significant structural difference is the torsion angle describing the twist ob benzoyl's phenyl ring defined as ϕ₂ – for IIa it is equal to −0.26°, while for IIb 20.18°. To see how the potential energy changes with the conformation of the benzoyl group, a theoretical calculations were carried out with Gaussian 09. At each point of plot, the ϕ₁ and ϕ₂ torsions were fixed at the certain value and the rest of the molecule was allowed to optimize at B3LYP/6-31G** level of theory. Calculations show that there is one energetic minimum for ϕ₁ = ϕ₂ = 0°. This suggests that structure IIb is less favorable. In the second structure the disorder of the phenyl group on nitrogen atom is present. This kind of disorder was also noticed in the theoretical calculations. During the bensoyl's phenyl group rotation, the second phenyl ring switches between two positions. Whole process is visualized in the animation accessible via URL below: http://kchn.pg.gda.pl/ao/files/59kk_anim.htm. Synthetic, structural and theoretical details were discussed within the poster.
2017
Andrzej Okuniewski,
Damian Rosiak,
Jarosław Chojnacki
1-Benzoylthioureas contain both carbonyl and thiocarbonyl functional groups and are of interest for their biological activity, metal coordination ability and involvement in hydrogen-bond formation. Two novel 1-benzoylthiourea derivatives, namely 1-benzoyl-3-(3,4-dimethoxyphenyl)thiourea, C₁₆H₁₆N₂O₃S, (I), and 1-benzoyl-3-(2-hydroxypropyl)thiourea, C₁₁H₁₄N₂O₂S, (II), have been synthesized and characterized. Compound (I) crystallizes in the space group P1̅, while (II) crystallizes in the space group P2₁/c. In both structures, intramolecular N-H···O hydrogen bonding is present. The resulting six-membered pseudo-rings are quasi-aromatic and, in each case, interact with phenyl rings via stacking-type inter­actions. C−H···O, C−H···S and C−H···π interactions are also present. In (I), there is one molecule in the asymmetric unit. Pairs of molecules are connected via two intermolecular N-H···S hydrogen bonds, forming centrosymmetric dimers. In (II), there are two symmetry-independent molecules that differ mainly in the relative orientations of the phenyl rings with respect to the thiourea cores. Additional strong hydrogen-bond donor and acceptor -OH groups participate in the formation of inter­molecular N−H···O and O−H···S hydrogen bonds that join molecules into chains extending in the [001] direction.
2017
Andrzej Okuniewski,
Damian Rosiak,
Jarosław Chojnacki,
Barbara Becker
4,6-Dimethyl-2-pyrimido(thio)nium salts were synthesized by the reaction of (thio)urea, acetylacetone and hydrogen halide in acetone at room temperature. Crystals of the compounds were obtained by slow evaporation of the solvent from mixtures after reaction. Single-crystal X-ray diffraction analysis has shown that these compounds form layered structures. Moreover, in the case of urea derivatives luminescent properties has been observed. Obtained compounds exhibit similar hydrogen bond patterns that involves the anions. In all structures there are charge assisted N+−H···X− hydrogen bonds that build up straight or zig-zag chains as well as weaker C−H···X− interactions. Moot interactions of the halide anions with the aromatic rings can also be considered to exist. Structures of these compounds will be compared to already known chlorides.
2016
Damian Rosiak,
Andrzej Okuniewski,
Jarosław Chojnacki
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