ABSTRACT
N-grafted copolymers of chitosan (460 kDa) with poly(N-vinylpyrrolidone) (2.4 kDa) or poly(vinyl alcohol) (2.0 âkDa) as side chains were synthesized. Depending on the polymer-to-chitosan mass ratio the degree of amino group substitution with side chains in chitosan backbone was varied in the range of 0.01-0.33. Layer-by-layer films consisted of copolymers and dextran sulfate as polyanion were obtained. Thickness, hydrophilicity, and morphology of the films were investigated using QCM, UV-vis spectrophotometry, AFM, and contact angle measurements. The obtained films show enhanced protein-repellent properties in fetal bovine serum medium. The mass of adsorbed proteins on LbL films based on copolymer with a degree of substitution of 0.2 decreases by 50 â% compared to unmodified chitosan. Protein-repellent properties of copolymer-based films are common for LbL films of grafted chitosan copolymers and depend on hydrophilic side chain density on the surface.
ABSTRACT
Vibrational states of the newly synthesized molecule N'-(Adamantan-2-ylidene)thiophene-2-carbohydrazide, a potential antibacterial agent, are examined experimentally for the crystalline phase and analyzed based on quantum chemical modelling of the solitary molecule and of the dimer, and assignment of the observed vibrational frequencies is proposed. Modelling of the title molecule dimer is found to describe better the experimentally observed vibration frequencies for the crystalline phase than calculations performed for a solitary molecule. Contributions from adamantane and thiophene parts within the molecule are identified. Additionally, multiple hydrogen bonds have been revealed both experimentally and computationally, inherent in the crystalline phase contrary to a solitary molecule. The spectroscopic findings correlate with the calculated interatomic distances which were found to change in the dimer versus a single molecule and to correspond better to the X-ray analysis data of the title compound in the crystalline phase.