Novel Highly Efficient Antibacterial Chitosan-Based Films.

In this study, we elaborated new chitosan-based films reinforced by iron(III)-containing chitosan nanoparticles Fe(III)-CS-NPs at different concentrations. We found that the optimum concentration of Fe(III)-CS-NPs for the improvement of antibacterial and mechanical properties of the films was 10% (σb = ca. 8.8 N/mm2, εb = ca. 41%, inhibition zone for S. aureus = ca. 16.8 mm and for E. coli = ca. 11.2 mm). Also, using the click-chemistry approach (thiol-ene reaction), we have synthesized a novel water-soluble cationic derivative of chitin. The addition of this derivative of chitin to the chitosan polymer matrix of the elaborated film significantly improved its mechanical (σb = ca. 11.6 N/mm2, εb = ca. 75%) and antimicrobial (inhibition zone for S. aureus = ca. 19.6 mm and for E. coli = ca. 14.2 mm) properties. The key mechanism of the antibacterial action of the obtained films is the disruption of the membranes of bacterial cells. The elaborated antibacterial films are of interest for potential biomedical and food applications.

Crystal structure and Hirshfeld surface analysis of methyl 4'-amino-3',5'-di-cyano-2,2''-dioxodi-spiro[indoline-3,1'-cyclo-pentane-2',3''-indolin]-3'-ene-5'-carboximidate with an unknown solvent.

In the title compound, C23H16N6O3, the central five-membered cyclo-pentene ring adopts an envelope conformation while the five-membered spiro 2,3-di-hydro-1H-pyrrole rings exhibit twisted envelope and envelope conformations. One of the 1,3-di-hydro-2H-indol-2-one units is in an axial position and the other is in a bis-ectional position. The methyl methanimidate unit is in an equatorial position. The crystal structure of the title compound is consolidated by inter-molecular N-H⋯N, N-H⋯O and C-H⋯O hydrogen bonds, forming a three dimensional network.

Crystal structure and Hirshfeld surface analysis of 4-bromo-2-[3-methyl-5-(2,4,6-tri-methyl-benz-yl)oxazolidin-2-yl]phenol.

The title compound, C20H24BrNO2, is chiral at the carbon atoms on either side of the oxygen atom of the oxazolidine ring and crystallizes as a racemate. The 1,3-oxazolidine ring adopts an envelope conformation with the N atom in an endo position. The mean plane of the oxazolidine ring makes dihedral angles of 77.74 (10) and 45.50 (11)°, respectively, with the 4-bromo-phenol and 1,3,5-tri-methyl-benzene rings. In the crystal, adjacent mol-ecules are connected via C-H⋯O hydrogen bonds and C-H⋯π inter-actions into layers parallel to the (200) plane. The packing is strengthened by van der Waals inter-actions between parallel mol-ecular layers. A Hirshfeld surface analysis shows that H⋯H (58.2%), C⋯H/H⋯C (18.9%), and Br⋯H/H⋯Br (11.5%) inter-actions are the most abundant in the crystal packing.