Revealing the Effect of Stereocontrol on Intermolecular Interactions between Abiotic, Sequence-Defined Polyurethanes and a Ligand.

The development of precision polymer synthesis has facilitated access to a diverse library of abiotic structures wherein chiral monomers are positioned at specific locations within macromolecular chains. These structures are anticipated to exhibit folding characteristics similar to those of biotic macromolecules and possess comparable functionalities. However, the extensive sequence space and numerous variables make selecting a sequence with the desired function challenging. Therefore, revealing sequence-function dependencies and developing practical tools are necessary to analyze their conformations and molecular interactions. In this study, we investigate the effect of stereochemistry, which dictates the spatial location of backbone and pendant groups, on the interaction between sequence-defined oligourethanes and bisphenol A ligands. Various methods are explored to analyze the receptor-like properties of model oligomers and the ligand. The accuracy of molecular dynamics simulations and experimental techniques is assessed to uncover the impact of discrete changes in stereochemical arrangements on the structures of the resulting complexes and their binding strengths. Detailed computational investigations providing atomistic details show that the formed complexes demonstrate significant structural diversity depending on the sequence of stereocenters, thus affecting the oligomer-ligand binding strength. Among the tested techniques, the fluorescence spectroscopy data, fitted to the Stern-Volmer equation, are consistently aligned with the calculations, thus validating the developed simulation methodology. The developed methodology opens a way to engineer the structure of sequence-defined oligomers with receptor-like functionality to explore their practical applications, e.g., as sensory materials.

Sequence of monomers and position of stereocenters matter for thermal properties of stereocontrolled oligourethanes.

Polyurethanes are commodity materials used for multiple applications. In recent years, a new category of polyurethane material has emerged, characterized by the lack of polymer molar mass distribution, control of the monomer arrangement in the chain, and even full stereocontrol. Various multistep synthesis strategies have been developed to fabricate sequence-defined polyurethanes. However, synthesizing stereocontrolled polyurethanes with a controlled sequence is still a challenge. Polyurethanes with structural precision, as represented by biopolymers, i.e. proteins or nucleic acids, have opened new application directions for these groups of materials. It has been shown that polyurethanes can be used as biomimetics, information carriers, molecular tags, and materials with strictly controlled properties. Precise synthesis of macromolecules allows us to fine-tune the properties of polymers to specific needs. Therefore, it is essential to collect information on the sequence-structure relationship of polymers. In our work, we present synthetic pathways to make sequence and stereo-defined oligourethanes. We demonstrate that structural details, i.e., the monomer sequences and position of the stereocenter, have a tremendous effect on the thermal properties of model oligourethanes. We show that the introduction of chirality by constitutional isomerization can be used to program the thermal characteristics of polymers, which are key features for material applications.

Shaping Macromolecules for Sensing Applications-From Polymer Hydrogels to Foldamers.

Sensors are tools for detecting, recognizing, and recording signals from the surrounding environment. They provide measurable information on chemical or physical changes, and thus are widely used in diagnosis, environment monitoring, food quality checks, or process control. Polymers are versatile materials that find a broad range of applications in sensory devices for the biomedical sector and beyond. Sensory materials are expected to exhibit a measurable change of properties in the presence of an analyte or a stimulus, characterized by high sensitivity and selectivity of the signal. Signal parameters can be tuned by material features connected with the restriction of macromolecule shape by crosslinking or folding. Gels are crosslinked, three-dimensional networks that can form cavities of different sizes and forms, which can be adapted to trap particular analytes. A higher level of structural control can be achieved by foldamers, which are macromolecules that can attain well-defined conformation in solution. By increasing control over the three-dimensional structure, we can improve the selectivity of polymer materials, which is one of the crucial requirements for sensors. Here, we discuss various examples of polymer gels and foldamer-based sensor systems. We have classified and described applied polymer materials and used sensing techniques. Finally, we deliberated the necessity and potential of further exploration of the field towards the increased selectivity of sensory devices.