The influence on the resistance formation of polymers attached to antibiotics has rarely been investigated. In this study, ciprofloxacin (CIP) was conjugated to poly(2-methyl-2-oxazoline)s with an ethylene diamine end group (Me-PMOx-EDA) via two different spacers (CIP modified with α,α'-dichloro- p-xylene-xCIP, CIP modified with chloroacetyl chloride-eCIP). The antibacterial activity of the conjugates against a number of bacterial strains shows a great dependence on the nature of the spacer. The Me-PMOx-EDA-eCIP, containing a potentially cleavable linker, does not exhibit a molecular weight dependence on antibacterial activity in contrast to Me-PMOx-EDA-xCIP. The resistance formation of both conjugates against Staphylococcus aureus and Escherichia coli was investigated. Both conjugates showed the potential to significantly delay the formation of resistant bacteria compared to the unmodified CIP. Closer inspection of a possible resistance mechanism by genome sequencing of the topoisomerase IV region of resistant S. aureus revealed that this bacterium mutates at the same position when building up resistance to CIP and to Me-PMOx-EDA-xCIP. However, the S. aureus cells that became resistant against the polymer conjugate are fully susceptible to CIP. Thus, conjugation of CIP with PMOx seems to alter the resistance mechanism.

The coordination contacts to the metal lithium allow the desymmetrisation of dimethoxysilanes by substitution with organolithiums under high kinetic stereocontrol.

The title compounds, C13H18O3Si (1) and C18H20O3Si (2), represent functionalizable dihydrofuranylsilanes, which permit substitution by a variety of nucleophiles. The crystal structures of 1 and 2 display weak intermolecular C—H...O hydrogen-bonding interactions (quantified by Hirshfeld surface analysis), leading to a two-dimensional supramolecular network for 1 and a one-dimensional supramolecular network for 2. The crystal structures of 1 and 2 were refined both on the basis of the independent atom model (IAM) and the Hirshfeld atom refinement (HAR) approach, and the results are comparatively discussed.

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The title compounds, C10H16O2Si (1) and C17H18OSi (2), are classified as dihydrofurylsilanes, which show great potential as building blocks for various functionalized silanes. They both crystallize in the space group P\overline{1} in the triclinic crystal system. Analyses of the Hirshfeld surfaces show packing-determining interactions for both compounds, resulting in a polymeric chain along the [011] for silane 1 and a layered-interconnected structure along the b-axis direction for silane 2.