New Antibacterial and Antioxidant Chitin Derivatives: Ultrasonic Preparation and Biological Effects.

This work focuses on the first use of ultrasonic phenol-ene coupling as a polymer analogous transformation. The ultrasonic reaction was introduced into chitin chemistry, resulting in the fast and convenient preparation of new water-soluble cationic chitin derivatives. Since water-soluble derivatives of fully deacetylated chitin are poorly described in the literature, the synthesis of each new type of these derivatives is a significant event in polysaccharide chemistry. Polycations, or cationic polymers, are of particular interest as antibacterial agents. Consequently, the resulting polymers were tested for their antibacterial activity and toxicity. We found that the highly substituted polymer of medium molecular weight exhibited the most pronounced in vitro antibacterial effect. We prepared nanoparticles using the ionic gelation technique. The most effective in vitro antibacterial chitin-based systems were tested in vivo in rats. These tests demonstrated outstanding antibacterial effects combined with an absence of toxicity. Additionally, we found that the resulting polymers, unlike their nanoparticle counterparts, also exhibited strong antioxidant effects. In summary, we demonstrated the effectiveness of ultrasound in polymer chemistry and highlighted the importance of the sonochemical approach in the chemical modification of polysaccharides. This approach enables the synthesis of derivatives with improved physicochemical and biological properties.

Crystal structure and Hirshfeld surface analysis of (2E)-1-phenyl-3-(1H-pyrrol-2-yl)propen-1-one.

The title com-pound, C13H11NO, adopts an E configuration about the C=C double bond. The pyrrole ring is inclined to the phenyl ring at an angle of 44.94 (8)°. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds, forming ribbons parallel to (020) in zigzag C(7) chains along the a axis. These ribbons are connected via C-H⋯π inter-actions, forming a three-dimensional network. No significant π-π inter-actions are observed.

Crystal structure and Hirshfeld surface analysis of 1-(2-amino-4-methyl-1,3-thia-zol-5-yl)ethan-1-one.

In the title compound, C6H8N2OS, all atoms except for the methyl H atoms are coplanar, with a maximum deviation of 0.026 (4) Å. In the crystal, pairs of mol-ecules are linked by N-H⋯N hydrogen bonds, forming R 2 2(8) ring motifs. Dimers are connected by N-H⋯O hydrogen bonds, forming layers parallel to the (102) plane. Consolidating the mol-ecular packing, these layers are connected by C-H⋯π inter-actions between the center of the 1,3-thia-zole ring and the H atom of the methyl group attached to it, as well as C=O⋯π inter-actions between the center of the 1,3-thia-zole ring and the O atom of the carboxyl group. According to a Hirshfeld surface study, H⋯H (37.6%), O⋯H/H⋯O (16.8%), S⋯H/H⋯S (15.4%), N⋯H/H⋯N (13.0%) and C⋯H/H⋯C (7.6%) inter-actions are the most significant contributors to the crystal packing.

Crystal structure and Hirshfeld surface analysis of 2-amino-5-{(1E)-1-[(carbamo-thioyl-amino)-imino]eth-yl}-4-methyl-1,3-thia-zol-3-ium chloride monohydrate.

In the hydrated title salt, C7H12N5S2 +·Cl-·H2O, the asymmetric unit comprises one 2-amino-5-{(1E)-1-[(carbamo-thioyl-amino)-imino]-eth-yl}-4-methyl-1,3-thia-zol-3-ium cation, one chloride anion and one water mol-ecule of crystallization. The cation is nearly flat (r.m.s. deviation of non-H atoms is 0.0814 Å), with the largest deviation of 0.1484 (14) Šobserved for one of the methyl C atoms. In the crystal, the cations are linked by O-H⋯Cl, N-H⋯Cl, N-H⋯O, N-H⋯S and C-H⋯S hydrogen bonds, forming a tri-periodic network. The most important contributions to the crystal packing are from H⋯H (35.4%), S⋯H/H⋯S (24.4%), N⋯H/H⋯N (8.7%), Cl⋯H/H⋯Cl (8.2%) and C⋯H/H⋯C (7.7%) inter-actions.

Structural Organization of Dibromodiazadienes in the Crystal and Identification of Br···O Halogen Bonding Involving the Nitro Group.

Nitro functionalized dibromodiazadiene dyes were prepared and fully characterized including X-ray single crystal analysis. Electron deficient dibromodiazadienes were found to be able to act as donors of halogen bonding (XB), while the nitro group acted as an acceptor of the XB. Depending on the substituents, the Br···O XB competed with other weak interactions, and for some of the dyes, they even outcompeted the XB involving the nitro group. However, the nitro functionalized dibromoalkenes 6a and 10a, which had only the nitro moiety as the most plausible acceptor of the XB, reliably formed 1D chains via Br⋯O XB. Experimental work was supported by the DFT calculations and topological analysis of the electron density distribution within the framework of Bader's theory (QTAIM method).

Halogenated Diazabutadiene Dyes: Synthesis, Structures, Supramolecular Features, and Theoretical Studies.

Novel halogenated aromatic dichlorodiazadienes were prepared via copper-mediated oxidative coupling between the corresponding hydrazones and CCl4. These rare azo-dyes were characterized using 1H and 13C NMR techniques and X-ray diffraction analysis for five halogenated dichlorodiazadienes. Multiple non-covalent halogen···halogen interactions were detected in the solid state and studied by DFT calculations and topological analysis of the electron density distribution within the framework of Bader's theory (QTAIM method). Theoretical studies demonstrated that non-covalent halogen···halogen interactions play crucial role in self-assembly of highly polarizable dichlorodiazadienes. Thus, halogen bonding can dictate a packing preference in the solid state for this class of dichloro-substituted heterodienes, which could be a convenient tool for a fine tuning of the properties of this novel class of dyes.

Crystal structure and Hirshfeld surface analysis of (E)-3-[(4-methyl-benzyl-idene)amino]-5-phenylthiazolidin-2-iminium bromide N,N-di-methyl-formamide monosolvate.

In the cation of the title salt, C17H18N3S+·Br-·C3H7NO, the central thia-zolidine ring adopts an envelope conformation with puckering parameters Q(2) = 0.310 (3) Šand φ(2) = 42.2 (6)°. In the crystal, each cation is connected to two anions by N-H⋯ Br hydrogen bonds, forming an R 4 2(8) motif parallel to the (10) plane. van der Waals inter-actions between the cations, anions and N,N-di-methyl-formamide mol-ecules further stabilize the crystal structure in three dimensions. The most important contributions to the surface contacts are from H⋯H (55.6%), C⋯H/H⋯C (17.9%) and Br⋯H/H⋯Br (7.0%) inter-actions, as concluded from a Hirshfeld analysis.

Crystal structure and Hirshfeld surface analysis of 1-(2-fluoro-phen-yl)-1H-tetra-zole-5(4H)-thione.

In the crystal of the title compound, C7H5FN4S, the mol-ecules are non-planar, with dihedral angle formed by least-squares planes of tetra-zole and benzene rings of 59.94 (8) °. The crystal packing is formed by N-H⋯S hydrogen bonds, which link the mol-ecules into centrosymmetric dimers with an R 2 2(8) ring motif, and by the offset face-to-face π-π stacking inter-actions between the benzene rings, which join the dimers into layers parallel to (100). The Hirshfeld surface analysis shows that the most important contributions to the surface contacts are from N⋯H/H⋯N (21.9%), S⋯H/H⋯S (21.1%), H⋯H (14.6%), F⋯H/H⋯F (11.8%) and C⋯H/H⋯C (9.5%) inter-actions.

Crystal structure and Hirshfeld surface analysis of 6-benzoyl-3,5-di-phenyl-cyclo-hex-2-en-1-one.

In the title compound, C25H20O2, the central cyclo-hexenone ring adopts an envelope conformation. The mean plane of the cyclo-hexenone ring makes dihedral angles of 87.66 (11) and 23.76 (12)°, respectively, with the two attached phenyl rings, while it is inclined by 69.55 (11)° to the phenyl ring of the benzoyl group. In the crystal, the mol-ecules are linked by C-H⋯O and C-H⋯π inter-actions, forming a three-dimensional network.

Crystal Structure and Hirshfeld Surface Analysis of Acetoacetanilide Based Reaction Products.

We report an unprecedented multicomponent reaction of acetoacetanilide with malononitrile leading to a structurally novel bicyclic product (9) in a high yield. The structure has been confirmed by X-ray crystallography and comparative Hirshfeld surface analysis of 5-cyano-2-hydroxy-2-methyl-N-phenyl-4-(yridine-4-yl)-6-(thiophen-2-yl)-3,4-dihydro-2H-pyran-3-carboxamide 2, 5-cyano-2-hydroxy-2-methyl-6-oxo-N-phenyl-4-(thiophen-2-yl)piperidine-3-carboxamide 4 and 2-(8-amino-7,8a-dicyano-1-imino-4a-methyl-3-oxo-2-phenyl-1,3,4,4a,5,8a-hexahydroisoquinolin-6(2H)-ylidene)-N-phenylacetamide 9.

Crystal structure and Hirshfeld surface analysis of (E)-3-(benzyl-idene-amino)-5-phenyl-thia-zolidin-2-iminium bromide.

The central thia-zolidine ring of the title salt, C16H16N3S+·Br-, adopts an envelope conformation, with the C atom bearing the phenyl ring as the flap atom. In the crystal, the cations and anions are linked by N-H⋯Br hydrogen bonds, forming chains parallel to the b-axis direction. Hirshfeld surface analysis and two-dimensional fingerprint plots indicate that the most important contributions to the crystal packing are from H⋯H (46.4%), C⋯H/H⋯C (18.6%) and H⋯Br/Br⋯H (17.5%) inter-actions.

Crystal structure and Hirshfeld surface analysis of 3-amino-5-phenyl-thia-zolidin-2-iminium bromide.

In the cation of the title salt, C9H12N3S+·Br-, the thia-zolidine ring adopts an envelope conformation with the C atom adjacent to the phenyl ring as the flap. In the crystal, N-H⋯Br hydrogen bonds link the components into a three-dimensional network. Weak π-π stacking inter-actions between the phenyl rings of adjacent cations also contribute to the mol-ecular packing. A Hirshfeld surface analysis was conducted to qu-antify the contributions of the different inter-molecular inter-actions and contacts.

Crystal structure and Hirshfeld surface analysis of (E)-3-[(4-chloro-benzyl-idene)amino]-5-phenyl-thia-zolidin-2-iminium bromide.

The title salt, C16H15ClN3S+·Br-, is isotypic with (E)-3-[(4-fluoro-benzyl-idene)amino]-5-phenyl-thia-zolidin-2-iminium bromide [Khalilov et al. (2019 ▸). Acta Cryst. E75, 662-666]. In the cation of the title salt, the atoms of the phenyl ring attached to the central thia-zolidine ring and the atom joining the thia-zolidine ring to the benzene ring are disordered over two sets of sites with occupancies of 0.570 (3) and 0.430 (3). The major and minor components of the disordered thia-zolidine ring adopt slightly distorted envelope conformations, with the C atom bearing the phenyl ring as the flap atom. In the crystal, centrosymmetrically related cations and anions are linked into dimeric units via N-H⋯Br hydrogen bonds, which are further connected by weak C-H⋯Br contacts into chains parallel to the a axis. Furthermore, not existing in the earlier report of (E)-3-[(4-fluoro-benzyl-idene)amino]-5-phenyl-thia-zolidin-2-iminium bromide, C-H⋯π inter-actions and π-π stacking inter-actions [centroid-to-centroid distance = 3.897 (2) Å] between the major components of the disordered phenyl ring contribute to the stabilization of the mol-ecular packing. Hirshfeld surface analysis and two-dimensional fingerprint plots indicate that the most important contributions for the crystal packing are from H⋯H (30.5%), Br⋯H/H⋯Br (21.2%), C⋯H/H⋯C (19.2%), Cl⋯H/H⋯Cl (13.0%) and S⋯H/H⋯S (5.0%) inter-actions.

Hydrogen and halogen bonding in the haloetherification products in chalcone.

Cooperative action of hydrogen and halogen bonding in the reaction of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-1-phenylprop-2-en-1-one with HCl or HBr in alcohol medium under microwave irradiation (20 W, 80 °C, 10 min) allows the isolation of the haloetherification products (2S,3S)-3-(3-tert-butyl-5-chloro-4-hydroxyphenyl)-2-chloro-3-ethoxy-1-phenylpropan-1-one, C21H24Cl2O3, (2S,3S)-2-bromo-3-(3-tert-butyl-5-bromo-4-hydroxyphenyl)-3-methoxy-1-phenylpropan-1-one, C20H22Br2O3, and (2S,3S)-2-bromo-3-(3-tert-butyl-5-bromo-4-hydroxyphenyl)-3-ethoxy-1-phenylpropan-1-one, C21H24Br2O3, in good yields. Both types of noncovalent interactions, e.g. hydrogen and halogen bonds, are formed to stabilize the obtained products in the solid state.

Crystal structure and Hirshfeld surface analysis of (E)-5-phenyl-3-[(pyridin-4-yl-methyl-idene)amino]-thia-zolidin-2-iminium bromide monohydrate.

In the cation of the title salt, C15H15N4S+·Br-·H2O, the central thia-zolidine ring adopts an envelope conformation with puckering parameters Q(2) = 0.279 (4) Šand φ(2) = 222.5 (9)°. The mean plane of the thia-zolidine ring makes dihedral angles of 12.4 (2) and 66.8 (3)° with the pyridine and phenyl rings, respectively. The pyridine ring in the title mol-ecule is essentially planar (r.m.s deviation = 0.005 Å). In the crystal, the cations, anions and water mol-ecules are linked into a three-dimensional network, which forms cross layers parallel to the (120) and (20) planes via O-H⋯Br, N-H⋯Br and N-H⋯N hydrogen bonds. C-H⋯π inter-actions also help in the stabilization of the mol-ecular packing. Hirshfeld surface analysis and 2D (two-dimensional) fingerprint plots indicate that the most important contributions to the crystal packing are from H⋯H (35.5%), C⋯H/H⋯C (23.9%), Br⋯H/H⋯Br (16.4%), N⋯H/H⋯N (10.6%) and S⋯H/H⋯S (7.9%) inter-actions.

Ethyl 4-(5-bromo-2-hy-droxy-phen-yl)-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexa-hydro-quinoline-3-carboxyl-ate.

In the title compound, C21H24BrNO4, the dihedral angle between the heterocyclic ring and the pendant aromatic ring is 80.20 (13)°. The hexahydroquinone [i.e. the one with the C=O group] ring adopts a sofa conformation. An intra-molecular O-H⋯O hydrogen bond generates an S(6) ring motif. The ethyl group is disordered over two sets of sites with a refined site occupancy ratio of 0.633 (10):0.366 (10). In the crystal, mol-ecules are linked by N-H⋯O inter-actions, forming chains parallel to [101]. There are no significant C-H⋯π or π-π inter-actions in the crystal structure.

rac-Ethyl 2-hy-droxy-2,7,7-trimethyl-4-(4-nitro-phen-yl)-5-oxo-3,4,5,6,7,8-hexa-hydro-2H-chromene-3-carboxyl-ate.

The title mol-ecule, C21H25NO7, has four stereogenic centres and crystallized as a racemate. It consists of enanti-omeric pairs with the relative configuration rac-(1R*,2S*,3R*). The cyclo-hexenone ring adopts an envelope conformation; the dimethyl-substituted C atom lies 0.640 (1) Šout of the mean plane formed by the rest of the ring atoms (r.m.s. deviation = 0.016 Å). The oxacyclo-hexene ring adopts a half-chair conformation, the hy-droxy- and carboxyl-substituted C atoms lying -0.336 (1) and 0.419 (1) Å, respectively, out of the mean plane formed by the rest of the ring atoms (r.m.s. deviation = 0.002 Å). In the crystal, O-H⋯O hydrogen bonds link the mol-ecules into a chain along the c-axis direction.

[N-(1-Aza-nidyl-2,2,2-trichloro-ethyl-idene)-2,2,2-trichloro-ethanimidamide]-copper(II).

The title compound, [Cu(C(4)H(2)Cl(6)N(3))(2)], was obtained by the reaction of CCl(3)CN with ammonia in presence of CuCl. The Cu(II) atom is located about an inversion centre. The mol-ecule consists of three planar units (one central square CuN(4) and two C(2)N(3) fragments), adopting a staircase-like structure. The six-membered metallocycles have a sofa conformation with the Cu atom out of the plane of the 1,3,5-triaza-penta-dienyl ligands by 0.246 (5) Å. The ipso-C atoms of the CCl(3) substituents are slightly out of the 1,3,5-triaza-penta-dienyl planes by 0.149 (6) and -0.106 (6) Å. The CCl(3) groups of each 1,3,5-triaza-penta-dienyl ligand are practically in the energetic-ally favourable mutually eclipsed conformation. In the crystal, the mol-ecules are packed in stacks along the a axis. The mol-ecules in the stacks are held together by two additional axial Cu⋯Cl inter-actions of 3.354 (2) Å. Taking the axial Cu⋯Cl inter-actions into account, the Cu(II) atom exhibits a distorted [4 + 2]-octa-hedral coordination environment. The stacks are bound to each other by weak inter-molecular attractive Cl⋯Cl [3.505 (2)-3.592 (3) Å] inter-actions.

Ethyl 2,7,7-trimethyl-5-oxo-4-phenyl-1,4,5,6,7,8-hexa-hydro-quinoline-3-carboxyl-ate.

In the title compound, C(21)H(25)NO(3), the hydro-pyridine ring that constitutes a part of the hexa-hydro-quinoline fused-ring system adopts a sofa conformation; the methine C atom deviates from the least-squares plane defined by the remaining five non-H atoms (r.m.s. deviation = 0.088 Å) by 0.454 (3) Å. The phenyl ring is aligned at 85.5 (1)° with respect to this mean plane. In the crystal, adjacent molecules are linked via an N-H⋯O hydrogen bond, involving the amino group and the carbonyl O atom of the fused-ring system, forming chains running along [100]. The ethyl group is disordered over two positions in a 0.609 (6):0.391 (6) ratio.

9-(2-Hy-droxy-4,4-dimethyl-6-oxocyclo-hex-1-en-1-yl)-3,3-dimethyl-2,3,4,9-tetra-hydro-1H-xanthen-1-one.

The cyclo-hexene ring that constitutes a part of the tetra-hydroxanthene fused-ring system of the title compound, C(23)H(26)O(4), adopts a flattened half-chair conformation that approximates an envelope conformation (in which the methyl-ene C atom bearing the two methyl substituents represents the flap) as five of the six atoms lie approximately on a plane (r.m.s. deviation = 0.020 Å). The mean plane of the cyclo-hexene ring with the hy-droxy substituent is approximately perpendicular to the mean plane of the tetra-hydroxanthene system. In the crystal, adjacent mol-ecules are linked by O-H⋯O(carbon-yl) hydrogen bonds into a chain running along the b axis.